Initial commit

20 files changed, 6123 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..f233ede
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,18 @@
+cmake_minimum_required(VERSION 3.13)
+project(slcl)
+add_executable(${PROJECT_NAME}
+    auth.c
+    base64.c
+    handler.c
+    html.c
+    http.c
+    jwt.c
+    main.c
+    page.c
+    server.c
+)
+target_compile_options(${PROJECT_NAME} PRIVATE -Wall)
+add_subdirectory(dynstr)
+find_package(cJSON 1.0 REQUIRED)
+find_package(OpenSSL 3.0 REQUIRED)
+target_link_libraries(${PROJECT_NAME} PRIVATE dynstr cjson OpenSSL::SSL)
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..be3f7b2
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  Developers that use our General Public Licenses protect your rights
+with two steps: (1) assert copyright on the software, and (2) offer
+you this License which gives you legal permission to copy, distribute
+and/or modify the software.
+
+  A secondary benefit of defending all users' freedom is that
+improvements made in alternate versions of the program, if they
+receive widespread use, become available for other developers to
+incorporate.  Many developers of free software are heartened and
+encouraged by the resulting cooperation.  However, in the case of
+software used on network servers, this result may fail to come about.
+The GNU General Public License permits making a modified version and
+letting the public access it on a server without ever releasing its
+source code to the public.
+
+  The GNU Affero General Public License is designed specifically to
+ensure that, in such cases, the modified source code becomes available
+to the community.  It requires the operator of a network server to
+provide the source code of the modified version running there to the
+users of that server.  Therefore, public use of a modified version, on
+a publicly accessible server, gives the public access to the source
+code of the modified version.
+
+  An older license, called the Affero General Public License and
+published by Affero, was designed to accomplish similar goals.  This is
+a different license, not a version of the Affero GPL, but Affero has
+released a new version of the Affero GPL which permits relicensing under
+this license.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
+
+  "This License" refers to version 3 of the GNU Affero General Public License.
+
+  "Copyright" also means copyright-like laws that apply to other kinds of
+works, such as semiconductor masks.
+
+  "The Program" refers to any copyrightable work licensed under this
+License.  Each licensee is addressed as "you".  "Licensees" and
+"recipients" may be individuals or organizations.
+
+  To "modify" a work means to copy from or adapt all or part of the work
+in a fashion requiring copyright permission, other than the making of an
+exact copy.  The resulting work is called a "modified version" of the
+earlier work or a work "based on" the earlier work.
+
+  A "covered work" means either the unmodified Program or a work based
+on the Program.
+
+  To "propagate" a work means to do anything with it that, without
+permission, would make you directly or secondarily liable for
+infringement under applicable copyright law, except executing it on a
+computer or modifying a private copy.  Propagation includes copying,
+distribution (with or without modification), making available to the
+public, and in some countries other activities as well.
+
+  To "convey" a work means any kind of propagation that enables other
+parties to make or receive copies.  Mere interaction with a user through
+a computer network, with no transfer of a copy, is not conveying.
+
+  An interactive user interface displays "Appropriate Legal Notices"
+to the extent that it includes a convenient and prominently visible
+feature that (1) displays an appropriate copyright notice, and (2)
+tells the user that there is no warranty for the work (except to the
+extent that warranties are provided), that licensees may convey the
+work under this License, and how to view a copy of this License.  If
+the interface presents a list of user commands or options, such as a
+menu, a prominent item in the list meets this criterion.
+
+  1. Source Code.
+
+  The "source code" for a work means the preferred form of the work
+for making modifications to it.  "Object code" means any non-source
+form of a work.
+
+  A "Standard Interface" means an interface that either is an official
+standard defined by a recognized standards body, or, in the case of
+interfaces specified for a particular programming language, one that
+is widely used among developers working in that language.
+
+  The "System Libraries" of an executable work include anything, other
+than the work as a whole, that (a) is included in the normal form of
+packaging a Major Component, but which is not part of that Major
+Component, and (b) serves only to enable use of the work with that
+Major Component, or to implement a Standard Interface for which an
+implementation is available to the public in source code form.  A
+"Major Component", in this context, means a major essential component
+(kernel, window system, and so on) of the specific operating system
+(if any) on which the executable work runs, or a compiler used to
+produce the work, or an object code interpreter used to run it.
+
+  The "Corresponding Source" for a work in object code form means all
+the source code needed to generate, install, and (for an executable
+work) run the object code and to modify the work, including scripts to
+control those activities.  However, it does not include the work's
+System Libraries, or general-purpose tools or generally available free
+programs which are used unmodified in performing those activities but
+which are not part of the work.  For example, Corresponding Source
+includes interface definition files associated with source files for
+the work, and the source code for shared libraries and dynamically
+linked subprograms that the work is specifically designed to require,
+such as by intimate data communication or control flow between those
+subprograms and other parts of the work.
+
+  The Corresponding Source need not include anything that users
+can regenerate automatically from other parts of the Corresponding
+Source.
+
+  The Corresponding Source for a work in source code form is that
+same work.
+
+  2. Basic Permissions.
+
+  All rights granted under this License are granted for the term of
+copyright on the Program, and are irrevocable provided the stated
+conditions are met.  This License explicitly affirms your unlimited
+permission to run the unmodified Program.  The output from running a
+covered work is covered by this License only if the output, given its
+content, constitutes a covered work.  This License acknowledges your
+rights of fair use or other equivalent, as provided by copyright law.
+
+  You may make, run and propagate covered works that you do not
+convey, without conditions so long as your license otherwise remains
+in force.  You may convey covered works to others for the sole purpose
+of having them make modifications exclusively for you, or provide you
+with facilities for running those works, provided that you comply with
+the terms of this License in conveying all material for which you do
+not control copyright.  Those thus making or running the covered works
+for you must do so exclusively on your behalf, under your direction
+and control, on terms that prohibit them from making any copies of
+your copyrighted material outside their relationship with you.
+
+  Conveying under any other circumstances is permitted solely under
+the conditions stated below.  Sublicensing is not allowed; section 10
+makes it unnecessary.
+
+  3. Protecting Users' Legal Rights From Anti-Circumvention Law.
+
+  No covered work shall be deemed part of an effective technological
+measure under any applicable law fulfilling obligations under article
+11 of the WIPO copyright treaty adopted on 20 December 1996, or
+similar laws prohibiting or restricting circumvention of such
+measures.
+
+  When you convey a covered work, you waive any legal power to forbid
+circumvention of technological measures to the extent such circumvention
+is effected by exercising rights under this License with respect to
+the covered work, and you disclaim any intention to limit operation or
+modification of the work as a means of enforcing, against the work's
+users, your or third parties' legal rights to forbid circumvention of
+technological measures.
+
+  4. Conveying Verbatim Copies.
+
+  You may convey verbatim copies of the Program's source code as you
+receive it, in any medium, provided that you conspicuously and
+appropriately publish on each copy an appropriate copyright notice;
+keep intact all notices stating that this License and any
+non-permissive terms added in accord with section 7 apply to the code;
+keep intact all notices of the absence of any warranty; and give all
+recipients a copy of this License along with the Program.
+
+  You may charge any price or no price for each copy that you convey,
+and you may offer support or warranty protection for a fee.
+
+  5. Conveying Modified Source Versions.
+
+  You may convey a work based on the Program, or the modifications to
+produce it from the Program, in the form of source code under the
+terms of section 4, provided that you also meet all of these conditions:
+
+    a) The work must carry prominent notices stating that you modified
+    it, and giving a relevant date.
+
+    b) The work must carry prominent notices stating that it is
+    released under this License and any conditions added under section
+    7.  This requirement modifies the requirement in section 4 to
+    "keep intact all notices".
+
+    c) You must license the entire work, as a whole, under this
+    License to anyone who comes into possession of a copy.  This
+    License will therefore apply, along with any applicable section 7
+    additional terms, to the whole of the work, and all its parts,
+    regardless of how they are packaged.  This License gives no
+    permission to license the work in any other way, but it does not
+    invalidate such permission if you have separately received it.
+
+    d) If the work has interactive user interfaces, each must display
+    Appropriate Legal Notices; however, if the Program has interactive
+    interfaces that do not display Appropriate Legal Notices, your
+    work need not make them do so.
+
+  A compilation of a covered work with other separate and independent
+works, which are not by their nature extensions of the covered work,
+and which are not combined with it such as to form a larger program,
+in or on a volume of a storage or distribution medium, is called an
+"aggregate" if the compilation and its resulting copyright are not
+used to limit the access or legal rights of the compilation's users
+beyond what the individual works permit.  Inclusion of a covered work
+in an aggregate does not cause this License to apply to the other
+parts of the aggregate.
+
+  6. Conveying Non-Source Forms.
+
+  You may convey a covered work in object code form under the terms
+of sections 4 and 5, provided that you also convey the
+machine-readable Corresponding Source under the terms of this License,
+in one of these ways:
+
+    a) Convey the object code in, or embodied in, a physical product
+    (including a physical distribution medium), accompanied by the
+    Corresponding Source fixed on a durable physical medium
+    customarily used for software interchange.
+
+    b) Convey the object code in, or embodied in, a physical product
+    (including a physical distribution medium), accompanied by a
+    written offer, valid for at least three years and valid for as
+    long as you offer spare parts or customer support for that product
+    model, to give anyone who possesses the object code either (1) a
+    copy of the Corresponding Source for all the software in the
+    product that is covered by this License, on a durable physical
+    medium customarily used for software interchange, for a price no
+    more than your reasonable cost of physically performing this
+    conveying of source, or (2) access to copy the
+    Corresponding Source from a network server at no charge.
+
+    c) Convey individual copies of the object code with a copy of the
+    written offer to provide the Corresponding Source.  This
+    alternative is allowed only occasionally and noncommercially, and
+    only if you received the object code with such an offer, in accord
+    with subsection 6b.
+
+    d) Convey the object code by offering access from a designated
+    place (gratis or for a charge), and offer equivalent access to the
+    Corresponding Source in the same way through the same place at no
+    further charge.  You need not require recipients to copy the
+    Corresponding Source along with the object code.  If the place to
+    copy the object code is a network server, the Corresponding Source
+    may be on a different server (operated by you or a third party)
+    that supports equivalent copying facilities, provided you maintain
+    clear directions next to the object code saying where to find the
+    Corresponding Source.  Regardless of what server hosts the
+    Corresponding Source, you remain obligated to ensure that it is
+    available for as long as needed to satisfy these requirements.
+
+    e) Convey the object code using peer-to-peer transmission, provided
+    you inform other peers where the object code and Corresponding
+    Source of the work are being offered to the general public at no
+    charge under subsection 6d.
+
+  A separable portion of the object code, whose source code is excluded
+from the Corresponding Source as a System Library, need not be
+included in conveying the object code work.
+
+  A "User Product" is either (1) a "consumer product", which means any
+tangible personal property which is normally used for personal, family,
+or household purposes, or (2) anything designed or sold for incorporation
+into a dwelling.  In determining whether a product is a consumer product,
+doubtful cases shall be resolved in favor of coverage.  For a particular
+product received by a particular user, "normally used" refers to a
+typical or common use of that class of product, regardless of the status
+of the particular user or of the way in which the particular user
+actually uses, or expects or is expected to use, the product.  A product
+is a consumer product regardless of whether the product has substantial
+commercial, industrial or non-consumer uses, unless such uses represent
+the only significant mode of use of the product.
+
+  "Installation Information" for a User Product means any methods,
+procedures, authorization keys, or other information required to install
+and execute modified versions of a covered work in that User Product from
+a modified version of its Corresponding Source.  The information must
+suffice to ensure that the continued functioning of the modified object
+code is in no case prevented or interfered with solely because
+modification has been made.
+
+  If you convey an object code work under this section in, or with, or
+specifically for use in, a User Product, and the conveying occurs as
+part of a transaction in which the right of possession and use of the
+User Product is transferred to the recipient in perpetuity or for a
+fixed term (regardless of how the transaction is characterized), the
+Corresponding Source conveyed under this section must be accompanied
+by the Installation Information.  But this requirement does not apply
+if neither you nor any third party retains the ability to install
+modified object code on the User Product (for example, the work has
+been installed in ROM).
+
+  The requirement to provide Installation Information does not include a
+requirement to continue to provide support service, warranty, or updates
+for a work that has been modified or installed by the recipient, or for
+the User Product in which it has been modified or installed.  Access to a
+network may be denied when the modification itself materially and
+adversely affects the operation of the network or violates the rules and
+protocols for communication across the network.
+
+  Corresponding Source conveyed, and Installation Information provided,
+in accord with this section must be in a format that is publicly
+documented (and with an implementation available to the public in
+source code form), and must require no special password or key for
+unpacking, reading or copying.
+
+  7. Additional Terms.
+
+  "Additional permissions" are terms that supplement the terms of this
+License by making exceptions from one or more of its conditions.
+Additional permissions that are applicable to the entire Program shall
+be treated as though they were included in this License, to the extent
+that they are valid under applicable law.  If additional permissions
+apply only to part of the Program, that part may be used separately
+under those permissions, but the entire Program remains governed by
+this License without regard to the additional permissions.
+
+  When you convey a copy of a covered work, you may at your option
+remove any additional permissions from that copy, or from any part of
+it.  (Additional permissions may be written to require their own
+removal in certain cases when you modify the work.)  You may place
+additional permissions on material, added by you to a covered work,
+for which you have or can give appropriate copyright permission.
+
+  Notwithstanding any other provision of this License, for material you
+add to a covered work, you may (if authorized by the copyright holders of
+that material) supplement the terms of this License with terms:
+
+    a) Disclaiming warranty or limiting liability differently from the
+    terms of sections 15 and 16 of this License; or
+
+    b) Requiring preservation of specified reasonable legal notices or
+    author attributions in that material or in the Appropriate Legal
+    Notices displayed by works containing it; or
+
+    c) Prohibiting misrepresentation of the origin of that material, or
+    requiring that modified versions of such material be marked in
+    reasonable ways as different from the original version; or
+
+    d) Limiting the use for publicity purposes of names of licensors or
+    authors of the material; or
+
+    e) Declining to grant rights under trademark law for use of some
+    trade names, trademarks, or service marks; or
+
+    f) Requiring indemnification of licensors and authors of that
+    material by anyone who conveys the material (or modified versions of
+    it) with contractual assumptions of liability to the recipient, for
+    any liability that these contractual assumptions directly impose on
+    those licensors and authors.
+
+  All other non-permissive additional terms are considered "further
+restrictions" within the meaning of section 10.  If the Program as you
+received it, or any part of it, contains a notice stating that it is
+governed by this License along with a term that is a further
+restriction, you may remove that term.  If a license document contains
+a further restriction but permits relicensing or conveying under this
+License, you may add to a covered work material governed by the terms
+of that license document, provided that the further restriction does
+not survive such relicensing or conveying.
+
+  If you add terms to a covered work in accord with this section, you
+must place, in the relevant source files, a statement of the
+additional terms that apply to those files, or a notice indicating
+where to find the applicable terms.
+
+  Additional terms, permissive or non-permissive, may be stated in the
+form of a separately written license, or stated as exceptions;
+the above requirements apply either way.
+
+  8. Termination.
+
+  You may not propagate or modify a covered work except as expressly
+provided under this License.  Any attempt otherwise to propagate or
+modify it is void, and will automatically terminate your rights under
+this License (including any patent licenses granted under the third
+paragraph of section 11).
+
+  However, if you cease all violation of this License, then your
+license from a particular copyright holder is reinstated (a)
+provisionally, unless and until the copyright holder explicitly and
+finally terminates your license, and (b) permanently, if the copyright
+holder fails to notify you of the violation by some reasonable means
+prior to 60 days after the cessation.
+
+  Moreover, your license from a particular copyright holder is
+reinstated permanently if the copyright holder notifies you of the
+violation by some reasonable means, this is the first time you have
+received notice of violation of this License (for any work) from that
+copyright holder, and you cure the violation prior to 30 days after
+your receipt of the notice.
+
+  Termination of your rights under this section does not terminate the
+licenses of parties who have received copies or rights from you under
+this License.  If your rights have been terminated and not permanently
+reinstated, you do not qualify to receive new licenses for the same
+material under section 10.
+
+  9. Acceptance Not Required for Having Copies.
+
+  You are not required to accept this License in order to receive or
+run a copy of the Program.  Ancillary propagation of a covered work
+occurring solely as a consequence of using peer-to-peer transmission
+to receive a copy likewise does not require acceptance.  However,
+nothing other than this License grants you permission to propagate or
+modify any covered work.  These actions infringe copyright if you do
+not accept this License.  Therefore, by modifying or propagating a
+covered work, you indicate your acceptance of this License to do so.
+
+  10. Automatic Licensing of Downstream Recipients.
+
+  Each time you convey a covered work, the recipient automatically
+receives a license from the original licensors, to run, modify and
+propagate that work, subject to this License.  You are not responsible
+for enforcing compliance by third parties with this License.
+
+  An "entity transaction" is a transaction transferring control of an
+organization, or substantially all assets of one, or subdividing an
+organization, or merging organizations.  If propagation of a covered
+work results from an entity transaction, each party to that
+transaction who receives a copy of the work also receives whatever
+licenses to the work the party's predecessor in interest had or could
+give under the previous paragraph, plus a right to possession of the
+Corresponding Source of the work from the predecessor in interest, if
+the predecessor has it or can get it with reasonable efforts.
+
+  You may not impose any further restrictions on the exercise of the
+rights granted or affirmed under this License.  For example, you may
+not impose a license fee, royalty, or other charge for exercise of
+rights granted under this License, and you may not initiate litigation
+(including a cross-claim or counterclaim in a lawsuit) alleging that
+any patent claim is infringed by making, using, selling, offering for
+sale, or importing the Program or any portion of it.
+
+  11. Patents.
+
+  A "contributor" is a copyright holder who authorizes use under this
+License of the Program or a work on which the Program is based.  The
+work thus licensed is called the contributor's "contributor version".
+
+  A contributor's "essential patent claims" are all patent claims
+owned or controlled by the contributor, whether already acquired or
+hereafter acquired, that would be infringed by some manner, permitted
+by this License, of making, using, or selling its contributor version,
+but do not include claims that would be infringed only as a
+consequence of further modification of the contributor version.  For
+purposes of this definition, "control" includes the right to grant
+patent sublicenses in a manner consistent with the requirements of
+this License.
+
+  Each contributor grants you a non-exclusive, worldwide, royalty-free
+patent license under the contributor's essential patent claims, to
+make, use, sell, offer for sale, import and otherwise run, modify and
+propagate the contents of its contributor version.
+
+  In the following three paragraphs, a "patent license" is any express
+agreement or commitment, however denominated, not to enforce a patent
+(such as an express permission to practice a patent or covenant not to
+sue for patent infringement).  To "grant" such a patent license to a
+party means to make such an agreement or commitment not to enforce a
+patent against the party.
+
+  If you convey a covered work, knowingly relying on a patent license,
+and the Corresponding Source of the work is not available for anyone
+to copy, free of charge and under the terms of this License, through a
+publicly available network server or other readily accessible means,
+then you must either (1) cause the Corresponding Source to be so
+available, or (2) arrange to deprive yourself of the benefit of the
+patent license for this particular work, or (3) arrange, in a manner
+consistent with the requirements of this License, to extend the patent
+license to downstream recipients.  "Knowingly relying" means you have
+actual knowledge that, but for the patent license, your conveying the
+covered work in a country, or your recipient's use of the covered work
+in a country, would infringe one or more identifiable patents in that
+country that you have reason to believe are valid.
+
+  If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
+or convey a specific copy of the covered work, then the patent license
+you grant is automatically extended to all recipients of the covered
+work and works based on it.
+
+  A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Remote Network Interaction; Use with the GNU General Public License.
+
+  Notwithstanding any other provision of this License, if you modify the
+Program, your modified version must prominently offer all users
+interacting with it remotely through a computer network (if your version
+supports such interaction) an opportunity to receive the Corresponding
+Source of your version by providing access to the Corresponding Source
+from a network server at no charge, through some standard or customary
+means of facilitating copying of software.  This Corresponding Source
+shall include the Corresponding Source for any work covered by version 3
+of the GNU General Public License that is incorporated pursuant to the
+following paragraph.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the work with which it is combined will remain governed by version
+3 of the GNU General Public License.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU Affero General Public License from time to time.  Such new versions
+will be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU Affero General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU Affero General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU Affero General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..7994456
--- /dev/null
+++ b/README.md
@@ -0,0 +1,205 @@
+# slcl, a suckless cloud
+
+`slcl` is a simple and fast implementation of a web file server, commonly
+known as "cloud storage" or simply "cloud", written in C99.
+
+## Disclaimer
+
+While `slcl` might not share some of the philosophical views from the
+[suckless project](https://suckless.org), it still strives towards minimalism,
+simplicity and efficiency.
+
+## Features
+
+- Private access directory with file uploading.
+- Read-only public file sharing.
+- Its own, tiny HTTP/1.0 and 1.1-compatible server.
+- A simple JSON file as the credentials database.
+- No JavaScript.
+
+### TLS
+
+In order to maintain simplicity and reduce the risk for security bugs, `slcl`
+does **not** implement TLS support. Instead, this should be provided by a
+reverse proxy, such as [`caddy`](https://caddyserver.com/).
+
+### Root permissions
+
+`slcl` is expected to listen to connections from any port number so that `root`
+access is not required. So, in order to avoid the risk for security bugs,
+**please do not run `slcl` as `root`**.
+
+### Encryption
+
+Since no client-side JavaScript is used, files are **uploaded unencrypted**
+to `slcl`. If required, encryption should be done before uploading e.g.: using
+[`gpg`](https://gnupg.org/).
+
+## Requirements
+
+- A POSIX environment.
+- OpenSSL >= 3.0.
+- cJSON >= 1.7.15.
+- [`dynstr`](https://gitea.privatedns.org/xavi92/dynstr)
+(provided as a `git` submodule).
+- `xxd` (for [`usergen`](/usergen) only).
+- CMake (optional).
+
+### Ubuntu / Debian
+
+```sh
+sudo apt install libcjson-dev libssl-dev xxd
+```
+
+## How to use
+### Build
+
+Two build environments are provided for `slcl` - feel free to choose any of
+them:
+
+- A mostly POSIX-compliant [`Makefile`](/Makefile).
+- A [`CMakeLists.txt`](/CMakeLists.txt).
+
+`slcl` can be built using the standard build process:
+
+#### Make
+
+```sh
+$ make
+```
+
+#### CMake
+
+```sh
+$ mkdir build/
+$ cmake ..
+$ cmake --build .
+```
+
+### Setting up
+
+`slcl` consumes a path to a directory with the following tree structure:
+
+```
+.
+├── db.json
+├── public
+└── user
+```
+
+Where:
+
+- `db.json` is the credentials database. Details are explained below.
+    - **Note:** `slcl` creates a database with no users if not found, with
+    file mode bits set to `0600`.
+- `public` is a directory containing read-only files that can be accessed
+without authentication. Internally, they are implemented as simlinks to
+other files.
+    - **Note:** this directory must be created before running `slcl`.
+- `user` is a directory containing user directories, which in turn contain
+anything users put into them.
+    - **Note:** this directory must be created before running `slcl`.
+
+A more complete example:
+
+```
+.
+├── db.json
+├── public
+│   └── 416d604c03a1cbb2 -> user/alice/file.txt
+└── user
+    ├── alice
+    │   └── file.txt
+    └── john
+        └── file2.txt
+```
+
+**Note:** user directories (`alice` and `john` on the example above) must be
+created before running `slcl`.
+
+### Credentials database
+
+`slcl` reads credentials from the `db.json` database, with the following
+schema:
+
+```json
+{
+    "users": [{
+        "name":	"...",
+        "password":	"...",
+        "salt":	"...",
+        "key":	"..."
+    }]
+}
+```
+
+[`usergen`](/usergen) is an interactive script that consumes a username and
+password, and writes a JSON object that can be appended to the `users` JSON
+array in `db.json`. A salt is randomly generated using `openssl` and passwords
+are hashed multiple times beforehand - see [`usergen`](/usergen) and
+[`auth.c`](/auth.c) for further reference. Also, a random key is generated
+that is later used to sign HTTP cookies.
+
+When users authenticate from a web browser, `slcl` sends a SHA256HMAC-signed
+[JSON Web Token](https://jwt.io), using the random key generated by
+[`usergen`](/usergen). No session data is kept on the server.
+
+### Running
+
+To run `slcl`, simply run the executable with the path to a directory including
+the files listed above. By default, `slcl` will listen to incoming connections
+on a random TCP port number. To set a specific port number, use the `-p`
+command line option. For example:
+
+```sh
+slcl -p 7822 ~/my-db/
+```
+
+## Why this project?
+
+Previously, I had been recommended Nextcloud as an alternative to proprietary
+services like Dropbox. Unfortunately, despite being a very flexible piece of
+software, Nextcloud is _way too_ heavy on resources, specially on lower end
+hardware such as the Raspberry Pi 3:
+
+- It uses around **30%** RAM on my Raspberry Pi 3, configured with 973 MiB of
+RAM, and of course it gets worse with several simultaneous users.
+- Simple operations like searching and previewing files cause large amounts
+of I/O and RAM usage, so much that it locks the whole server up more often than
+not.
+- Nextcloud pages are bloated. Even the login page is over **15 MiB** (!).
+- Requires clients to run JavaScript, which also has a significant performance
+penalty on the web browser. Also, some users do not feel comfortable running
+JavaScript from their web browsers, and thus prefer to disable it.
+
+After years of recurring frustration as a Nextcloud administrator and user,
+I looked for alternatives that stripped out most of the unneeded bloat from
+Nextcloud, while providing the required features listed above. However,
+I could not find any that fit them, so I felt challenged to design a new
+implementation.
+
+On the other hand, command line-based solutions like `rsync` might not be as
+convenient for non-technical people, compared to a web browser, or might not
+be even available e.g.: phones.
+
+## License
+
+```
+slcl, a suckless cloud.
+Copyright (C) 2023  Xavier Del Campo Romero
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+```
+
+Also, see [`LICENSE`](/LICENSE).
diff --git a/auth.c b/auth.c
new file mode 100644
index 0000000..630bb0a
--- /dev/null
+++ b/auth.c
@@ -0,0 +1,472 @@
+#include "auth.h"
+#include "http.h"
+#include "jwt.h"
+#include <cjson/cJSON.h>
+#include <dynstr.h>
+#include <openssl/sha.h>
+#include <errno.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+struct auth
+{
+    struct dynstr dir, db;
+};
+
+enum {KEYLEN = 32};
+
+static char *dump_db(const char *const path)
+{
+    char *ret = NULL;
+    FILE *f = NULL;
+    struct stat sb;
+
+    if (stat(path, &sb))
+    {
+        fprintf(stderr, "%s: stat(2): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (sb.st_size > SIZE_MAX)
+    {
+        fprintf(stderr, "%s: %s too big (%llu bytes, %zu max)\n",
+            __func__, path, (unsigned long long)sb.st_size, (size_t)SIZE_MAX);
+        goto end;
+    }
+    else if (!(f = fopen(path, "rb")))
+    {
+        fprintf(stderr, "%s: fopen(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (!(ret = malloc(sb.st_size + 1)))
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (!fread(ret, sb.st_size, 1, f))
+    {
+        fprintf(stderr, "%s: failed to dump %zu bytes, ferror=%d\n",
+            __func__, (size_t)sb.st_size, ferror(f));
+        goto end;
+    }
+
+    ret[sb.st_size] = '\0';
+
+end:
+
+    if (f && fclose(f))
+    {
+        fprintf(stderr, "%s: fclose(3): %s\n", __func__, strerror(errno));
+        free(ret);
+        return NULL;
+    }
+
+    return ret;
+}
+
+static int decode_hex(const char *const hex, unsigned char *buf, size_t n)
+{
+    for (const char *s = hex; *s; s += 2)
+    {
+        const char nibble[sizeof "00"] = {*s, *(s + 1)};
+
+        if (!n)
+            return -1;
+
+        *buf++ = strtoul(nibble, NULL, 16);
+        n--;
+    }
+
+    return n ? -1 : 0;
+}
+
+static int find_cookie(const cJSON *const users, const char *const cookie)
+{
+    const cJSON *u;
+
+    cJSON_ArrayForEach(u, users)
+    {
+        const cJSON *const n = cJSON_GetObjectItem(u, "name"),
+            *const k = cJSON_GetObjectItem(u, "key");
+        const char *name, *key;
+        unsigned char dkey[KEYLEN];
+
+        if (!n || !(name = cJSON_GetStringValue(n)))
+        {
+            fprintf(stderr, "%s: missing username\n", __func__);
+            return -1;
+        }
+        else if (!k || !(key = cJSON_GetStringValue(k)))
+        {
+            fprintf(stderr, "%s: missing key\n", __func__);
+            return -1;
+        }
+        else if (decode_hex(key, dkey, sizeof dkey))
+        {
+            fprintf(stderr, "%s: decode_hex failed\n", __func__);
+            return -1;
+        }
+
+        const int res = jwt_check(cookie, dkey, sizeof dkey);
+
+        if (!res)
+            return 0;
+        if (res < 0)
+        {
+            fprintf(stderr, "%s: jwt_decode failed\n", __func__);
+            return -1;
+        }
+    }
+
+    return 1;
+}
+
+int auth_cookie(const struct auth *const a, const struct http_cookie *const c)
+{
+    int ret = -1;
+    char *db = NULL;
+    cJSON *json = NULL;
+
+    if (!c->field || !c->value)
+        return 1;
+    else if (!(db = dump_db(a->db.str)))
+    {
+        fprintf(stderr, "%s: dump_db failed\n", __func__);
+        goto end;
+    }
+    else if (!(json = cJSON_Parse(db)))
+    {
+        fprintf(stderr, "%s: cJSON_Parse failed\n", __func__);
+        goto end;
+    }
+
+    const cJSON *const users = cJSON_GetObjectItem(json, "users");
+
+    if (!users)
+    {
+        fprintf(stderr, "%s: could not find users\n", __func__);
+        goto end;
+    }
+    else if (!cJSON_IsArray(users))
+    {
+        fprintf(stderr, "%s: expected JSON array for users\n", __func__);
+        goto end;
+    }
+    else if ((ret = find_cookie(users, c->value)) < 0)
+    {
+        fprintf(stderr, "%s: find_cookie failed\n", __func__);
+        goto end;
+    }
+
+end:
+    free(db);
+    cJSON_Delete(json);
+    return ret;
+}
+
+static int generate_cookie(const cJSON *const json, const char *const path,
+    const char *const name, const char *const key, char **const cookie)
+{
+    unsigned char dkey[KEYLEN];
+    int ret = -1;
+    char *jwt = NULL;
+
+    if (decode_hex(key, dkey, sizeof dkey))
+    {
+        fprintf(stderr, "%s: decode_hex failed\n", __func__);
+        goto end;
+    }
+    else if (!(jwt = jwt_encode(name, dkey, sizeof dkey)))
+    {
+        fprintf(stderr, "%s: jwt_encode failed\n", __func__);
+        goto end;
+    }
+    else if (!(*cookie = http_cookie_create(name, jwt)))
+    {
+        fprintf(stderr, "%s: http_cookie_create failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    free(jwt);
+    return ret;
+}
+
+static int compare_pwd(const char *const salt, const char *const password,
+    const char *const exp_password)
+{
+    int ret = -1;
+    enum {SALT_LEN = SHA256_DIGEST_LENGTH};
+    unsigned char dec_salt[SALT_LEN], sha256[SHA256_DIGEST_LENGTH];
+    const size_t slen = strlen(salt),
+        len = strlen(password), n = sizeof dec_salt + len;
+    unsigned char *const salted = malloc(n);
+
+    if (slen != SALT_LEN * 2)
+    {
+        fprintf(stderr, "%s: unexpected salt length: %zu\n", __func__, slen);
+        goto end;
+    }
+    else if (!salted)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (decode_hex(salt, dec_salt, sizeof dec_salt))
+    {
+        fprintf(stderr, "%s: decode_hex failed\n", __func__);
+        goto end;
+    }
+
+    memcpy(salted, dec_salt, sizeof dec_salt);
+    memcpy(salted + sizeof dec_salt, password, len);
+
+    if (!SHA256(salted, n, sha256))
+    {
+        fprintf(stderr, "%s: SHA256 (first round) failed\n", __func__);
+        goto end;
+    }
+
+    enum {ROUNDS = 1000 - 1};
+
+    for (int i = 0; i < ROUNDS; i++)
+        if (!SHA256(sha256, sizeof sha256, sha256))
+        {
+            fprintf(stderr, "%s: SHA256 failed\n", __func__);
+            goto end;
+        }
+
+    char sha256_str[sizeof
+        "00000000000000000000000000000000"
+        "00000000000000000000000000000000"];
+
+    for (struct {char *p; size_t i;} a = {.p = sha256_str};
+        a.i < sizeof sha256 / sizeof *sha256; a.i++, a.p += 2)
+        sprintf(a.p, "%02x", sha256[a.i]);
+
+    if (!strcmp(sha256_str, exp_password))
+        ret = 0;
+    else
+        /* Positive error code for password mismatch. */
+        ret = 1;
+
+end:
+    free(salted);
+    return ret;
+}
+
+int auth_login(const struct auth *const a, const char *const user,
+    const char *const password, char **const cookie)
+{
+    int ret = -1;
+    const char *const path = a->db.str;
+    char *const db = dump_db(path);
+    cJSON *json = NULL;
+
+    if (!db)
+    {
+        fprintf(stderr, "%s: dump_db failed\n", __func__);
+        goto end;
+    }
+    else if (!(json = cJSON_Parse(db)))
+    {
+        fprintf(stderr, "%s: cJSON_Parse failed\n", __func__);
+        goto end;
+    }
+
+    const cJSON *const users = cJSON_GetObjectItem(json, "users");
+
+    if (!users)
+    {
+        fprintf(stderr, "%s: could not find users\n", __func__);
+        goto end;
+    }
+    else if (!cJSON_IsArray(users))
+    {
+        fprintf(stderr, "%s: expected JSON array for users\n", __func__);
+        goto end;
+    }
+
+    cJSON *u;
+
+    cJSON_ArrayForEach(u, users)
+    {
+        const cJSON *const n = cJSON_GetObjectItem(u, "name"),
+            *const s = cJSON_GetObjectItem(u, "salt"),
+            *const p = cJSON_GetObjectItem(u, "password"),
+            *const k = cJSON_GetObjectItem(u, "key");
+        const char *name, *salt, *pwd, *key;
+
+        if (!n || !(name = cJSON_GetStringValue(n)))
+        {
+            fprintf(stderr, "%s: missing username\n", __func__);
+            goto end;
+        }
+        else if (!s || !(salt = cJSON_GetStringValue(s)))
+        {
+            fprintf(stderr, "%s: missing salt\n", __func__);
+            goto end;
+        }
+        else if (!p || !(pwd = cJSON_GetStringValue(p)))
+        {
+            fprintf(stderr, "%s: missing password\n", __func__);
+            goto end;
+        }
+        else if (!k || !(key = cJSON_GetStringValue(k)))
+        {
+            fprintf(stderr, "%s: missing key\n", __func__);
+            goto end;
+        }
+        else if (!strcmp(name, user))
+        {
+            const int res = compare_pwd(salt, password, pwd);
+
+            if (res < 0)
+            {
+                fprintf(stderr, "%s: generate_cookie failed\n", __func__);
+                goto end;
+            }
+            else if (!res)
+            {
+                if (generate_cookie(json, path, name, key, cookie))
+                {
+                    fprintf(stderr, "%s: generate_cookie failed\n", __func__);
+                    goto end;
+                }
+
+                ret = 0;
+                goto end;
+            }
+        }
+    }
+
+    ret = 1;
+
+end:
+    free(db);
+    cJSON_Delete(json);
+    return ret;
+}
+
+void auth_free(struct auth *const a)
+{
+    if (a)
+    {
+        dynstr_free(&a->dir);
+        dynstr_free(&a->db);
+    }
+
+    free(a);
+}
+
+const char *auth_dir(const struct auth *const a)
+{
+    return a->dir.str;
+}
+
+static int create_db(const char *const path)
+{
+    int ret = -1;
+    const int fd = open(path, O_WRONLY | O_CREAT, 0600);
+
+    if (fd < 0)
+    {
+        fprintf(stderr, "%s: open(2): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+
+    static const char db[] = "{\"users\": []}\n";
+
+    for (struct {size_t n; const void *p;}
+        a = {.n = strlen(db), .p = db}; a.n;)
+    {
+        const ssize_t n = write(fd, a.p, a.n);
+
+        if (n < 0)
+        {
+            fprintf(stderr, "%s: write(2): %s\n", __func__, strerror(errno));
+            goto end;
+        }
+
+        a.n -= n;
+        a.p = ((const char *)a.p) + n;
+    }
+
+    printf("Created login database at %s\n", path);
+    ret = 0;
+
+end:
+
+    if (fd >= 0 && close(fd))
+    {
+        fprintf(stderr, "%s: close(2): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    return ret;
+}
+
+static int init_db(struct auth *const a)
+{
+    struct stat sb;
+    const char *const path = a->db.str;
+
+    if (stat(path, &sb))
+    {
+        if (errno == ENOENT)
+            return create_db(path);
+        else
+        {
+            fprintf(stderr, "%s: stat(2): %s\n", __func__, strerror(errno));
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+struct auth *auth_alloc(const char *const dir)
+{
+    struct auth *const a = malloc(sizeof *a);
+
+    if (!a)
+    {
+        fprintf(stderr, "%s: malloc(3) auth: %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    *a = (const struct auth){0};
+
+    dynstr_init(&a->db);
+    dynstr_init(&a->dir);
+
+    if (dynstr_append(&a->dir, "%s", dir))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto failure;
+    }
+    else if (dynstr_append(&a->db, "%s/db.json", dir))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto failure;
+    }
+    else if (init_db(a))
+    {
+        fprintf(stderr, "%s: init_db failed\n", __func__);
+        goto failure;
+    }
+
+    return a;
+
+failure:
+    auth_free(a);
+    return NULL;
+}
diff --git a/auth.h b/auth.h
new file mode 100644
index 0000000..a4145aa
--- /dev/null
+++ b/auth.h
@@ -0,0 +1,13 @@
+#ifndef AUTH_H
+#define AUTH_H
+
+#include "http.h"
+
+struct auth *auth_alloc(const char *dir);
+void auth_free(struct auth *a);
+int auth_cookie(const struct auth *a, const struct http_cookie *c);
+int auth_login(const struct auth *a, const char *user, const char *password,
+    char **cookie);
+const char *auth_dir(const struct auth *a);
+
+#endif /* AUTH_H */
diff --git a/base64.c b/base64.c
new file mode 100644
index 0000000..b1d4737
--- /dev/null
+++ b/base64.c
@@ -0,0 +1,126 @@
+#include "base64.h"
+#include <openssl/evp.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+static void remove_lf(char *b64)
+{
+    while ((b64 = strchr(b64, '\n')))
+        memcpy(b64, b64 + 1, strlen(b64));
+}
+
+static size_t base64len(const size_t n)
+{
+    /* Read EVP_EncodeInit(3) for further reference. */
+    return ((n / 48) * 65) + (n % 48 ? 1 + ((n / 3) + 1) * 4 : 0);
+}
+
+static size_t decodedlen(const size_t n)
+{
+    return ((n / 64) * 48) + (n % 64 ? (n / 4) * 3 : 0);
+}
+
+char *base64_encode(const void *const buf, const size_t n)
+{
+    EVP_ENCODE_CTX *const ctx = EVP_ENCODE_CTX_new();
+    char *ret = NULL;
+    unsigned char *b64 = NULL;
+
+    if (!ctx)
+    {
+        fprintf(stderr, "%s: EVP_ENCODE_CTX_new failed\n", __func__);
+        goto end;
+    }
+
+    const size_t b64len = base64len(n);
+
+    if (!(b64 = malloc(b64len + 1)))
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+
+    EVP_EncodeInit(ctx);
+
+    size_t rem = n, done = 0;
+    int outl = b64len;
+
+    while (rem)
+    {
+        const size_t i = n - rem, inl = rem > 48 ? 48 : rem;
+        const unsigned char *const in = buf;
+
+        if (!EVP_EncodeUpdate(ctx, &b64[done], &outl, &in[i], inl))
+        {
+            fprintf(stderr, "%s: EVP_EncodeUpdate failed\n", __func__);
+            goto end;
+        }
+
+        done += outl;
+        rem -= inl;
+    }
+
+    EVP_EncodeFinal(ctx, b64, &outl);
+    ret = (char *)b64;
+    remove_lf(ret);
+
+end:
+    if (!ret)
+        free(b64);
+
+    EVP_ENCODE_CTX_free(ctx);
+    return ret;
+}
+
+void *base64_decode(const char *const b64, size_t *const n)
+{
+    void *ret = NULL;
+    const size_t len = strlen(b64), dlen = decodedlen(len);
+    EVP_ENCODE_CTX *const ctx = EVP_ENCODE_CTX_new();
+    unsigned char *const buf = malloc(dlen);
+
+    if (!buf)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (!ctx)
+    {
+        fprintf(stderr, "%s: EVP_ENCODE_CTX_new failed\n", __func__);
+        goto end;
+    }
+
+    EVP_DecodeInit(ctx);
+
+    size_t rem = len, done = 0;
+    int outl = dlen;
+
+    while (rem)
+    {
+        const size_t i = len - rem, inl = rem > 64 ? 64 : rem;
+        const unsigned char *const in = (const unsigned char *)b64;
+
+        if (EVP_DecodeUpdate(ctx, &buf[done], &outl, &in[i], inl) < 0)
+        {
+            fprintf(stderr, "%s: EVP_EncodeUpdate failed\n", __func__);
+            goto end;
+        }
+
+        done += outl;
+        rem -= inl;
+    }
+
+    EVP_DecodeFinal(ctx, buf, &outl);
+    *n = done;
+    ret = buf;
+
+end:
+    if (!ret)
+        free(buf);
+
+    EVP_ENCODE_CTX_free(ctx);
+    return ret;
+}
diff --git a/base64.h b/base64.h
new file mode 100644
index 0000000..6ca0f18
--- /dev/null
+++ b/base64.h
@@ -0,0 +1,9 @@
+#ifndef BASE64_H
+#define BASE64_H
+
+#include <stddef.h>
+
+char *base64_encode(const void *buf, size_t n);
+void *base64_decode(const char *b64, size_t *n);
+
+#endif /* BASE64_H */
diff --git a/handler.c b/handler.c
new file mode 100644
index 0000000..b152cf1
--- /dev/null
+++ b/handler.c
@@ -0,0 +1,336 @@
+#include "handler.h"
+#include "http.h"
+#include "server.h"
+#include <errno.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+struct handler
+{
+    const char *tmpdir;
+
+    struct handler_cfg
+    {
+        char *url;
+        enum http_op op;
+        handler_fn f;
+        void *user;
+    } *cfg;
+
+    struct server *server;
+    struct client
+    {
+        struct handler *h;
+        struct server_client *c;
+        struct http_ctx *http;
+        struct client *next;
+    } *clients;
+
+    size_t n_cfg;
+};
+
+static int on_read(void *const buf, const size_t n, void *const user)
+{
+    struct client *const c = user;
+
+    return server_read(buf, n, c->c);
+}
+
+static int on_write(const void *const buf, const size_t n, void *const user)
+{
+    struct client *const c = user;
+
+    return server_write(buf, n, c->c);
+}
+
+static int wildcard_cmp(const char *s, const char *p)
+{
+    while (*p && *s)
+    {
+        const char *const wc = strchr(p, '*');
+
+        if (!wc)
+            return strcmp(s, p);
+
+        const size_t n = wc - p;
+
+        if (n)
+        {
+            const int r = strncmp(s, p, n);
+
+            if (r)
+                return r;
+
+            p += n;
+            s += n;
+        }
+        else if (*(wc + 1) == *s)
+        {
+            p = wc + 1;
+            s += n;
+        }
+        else if (*(wc + 1) == '*')
+            p++;
+        else
+        {
+            s++;
+            p += n;
+        }
+    }
+
+    while (*p)
+        if (*p++ != '*')
+            return -1;
+
+    return 0;
+}
+
+static int on_payload(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    struct client *const c = user;
+    struct handler *const h = c->h;
+
+    for (size_t i = 0; i < h->n_cfg; i++)
+    {
+        const struct handler_cfg *const cfg = &h->cfg[i];
+
+        if (cfg->op == p->op && !wildcard_cmp(p->resource, cfg->url))
+            return cfg->f(p, r, cfg->user);
+    }
+
+    fprintf(stderr, "Not found: %s\n", p->resource);
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_NOT_FOUND
+    };
+
+    return 0;
+}
+
+static struct client *find_or_alloc_client(struct handler *const h,
+    struct server_client *const c)
+{
+    for (struct client *cl = h->clients; cl; cl = cl->next)
+    {
+        if (cl->c == c)
+            return cl;
+    }
+
+    struct client *const ret = malloc(sizeof *ret);
+
+    if (!ret)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        return NULL;
+    }
+
+    const struct http_cfg cfg =
+    {
+        .read = on_read,
+        .write = on_write,
+        .payload = on_payload,
+        .user = ret,
+        .tmpdir = h->tmpdir
+    };
+
+    *ret = (const struct client)
+    {
+        .c = c,
+        .h = h,
+        .http = http_alloc(&cfg)
+    };
+
+    if (!ret->http)
+    {
+        fprintf(stderr, "%s: http_alloc failed\n", __func__);
+        return NULL;
+    }
+
+    if (!h->clients)
+        h->clients = ret;
+    else
+    {
+        for (struct client *c = h->clients; c; c = c->next)
+            if (!c->next)
+            {
+                c->next = ret;
+                break;
+            }
+    }
+
+    return ret;
+}
+
+static void client_free(struct client *const c)
+{
+    if (c)
+        http_free(c->http);
+
+    free(c);
+}
+
+static int remove_client_from_list(struct handler *const h,
+    struct client *const c)
+{
+    int ret = -1;
+
+    if (server_client_close(h->server, c->c))
+    {
+        fprintf(stderr, "%s: server_client_close failed\n",
+            __func__);
+        goto end;
+    }
+
+    for (struct client *cl = h->clients, *prev = NULL; cl;
+        prev = cl, cl = cl->next)
+    {
+        if (cl == c)
+        {
+            if (!prev)
+                h->clients = c->next;
+            else
+                prev->next = cl->next;
+
+            break;
+        }
+    }
+
+    ret = 0;
+
+end:
+    client_free(c);
+    return ret;
+}
+
+int handler_listen(struct handler *const h, const short port)
+{
+    if (!(h->server = server_init(port)))
+    {
+        fprintf(stderr, "%s: server_init failed\n", __func__);
+        return -1;
+    }
+
+    for (;;)
+    {
+        bool exit, io;
+        struct server_client *const c = server_select(h->server, &io, &exit);
+
+        if (exit)
+        {
+            printf("Exiting...\n");
+            break;
+        }
+        else if (!c)
+        {
+            fprintf(stderr, "%s: server_select failed\n", __func__);
+            return -1;
+        }
+
+        struct client *const cl = find_or_alloc_client(h, c);
+
+        if (!cl)
+        {
+            fprintf(stderr, "%s: find_or_alloc_client failed\n", __func__);
+            return -1;
+        }
+        else if (io)
+        {
+            bool write, close;
+            const int res = http_update(cl->http, &write, &close);
+
+            if (res || close)
+            {
+                if (res < 0)
+                {
+                    fprintf(stderr, "%s: http_update failed\n", __func__);
+                    return -1;
+                }
+                else if (remove_client_from_list(h, cl))
+                {
+                    fprintf(stderr, "%s: remove_client_from_list failed\n",
+                        __func__);
+                    return -1;
+                }
+            }
+            else
+                server_client_write_pending(cl->c, write);
+        }
+    }
+
+    return 0;
+}
+
+static void free_clients(struct handler *const h)
+{
+    for (struct client *c = h->clients; c;)
+    {
+        struct client *const next = c->next;
+
+        server_client_close(h->server, c->c);
+        client_free(c);
+        c = next;
+    }
+}
+
+void handler_free(struct handler *const h)
+{
+    if (h)
+    {
+        for (size_t i = 0; i < h->n_cfg; i++)
+            free(h->cfg[i].url);
+
+        free(h->cfg);
+        free_clients(h);
+        server_close(h->server);
+    }
+
+    free(h);
+}
+
+struct handler *handler_alloc(const char *const tmpdir)
+{
+    struct handler *const h = malloc(sizeof *h);
+
+    if (!h)
+    {
+        fprintf(stderr, "%s: malloc(3) handler: %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+
+    *h = (const struct handler){.tmpdir = tmpdir};
+    return h;
+}
+
+int handler_add(struct handler *const h, const char *url,
+    const enum http_op op, const handler_fn f, void *const user)
+{
+    if (!h || !(h->cfg = realloc(h->cfg, (h->n_cfg + 1) * sizeof *h->cfg)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    char *const new = strdup(url);
+
+    if (!new)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    h->cfg[h->n_cfg++] = (const struct handler_cfg)
+    {
+        .url = new,
+        .op = op,
+        .f = f,
+        .user = user
+    };
+
+    return 0;
+}
diff --git a/handler.h b/handler.h
new file mode 100644
index 0000000..8550010
--- /dev/null
+++ b/handler.h
@@ -0,0 +1,17 @@
+#ifndef HANDLER_H
+#define HANDLER_H
+
+#include "http.h"
+#include <stddef.h>
+
+struct handler;
+typedef int (*handler_fn)(const struct http_payload *p,
+    struct http_response *r, void *user);
+
+struct handler *handler_alloc(const char *tmpdir);
+void handler_free(struct handler *h);
+int handler_add(struct handler *h, const char *url, enum http_op op,
+    handler_fn f, void *user);
+int handler_listen(struct handler *h, short port);
+
+#endif /* HANDLER_H */
diff --git a/html.c b/html.c
new file mode 100644
index 0000000..f5ea336
--- /dev/null
+++ b/html.c
@@ -0,0 +1,288 @@
+#include "html.h"
+#include <dynstr.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct html_node
+{
+    struct html_attribute
+    {
+        char *attr, *value;
+    } *attrs;
+
+    char *element, *value;
+    size_t n;
+    struct html_node *child, *sibling;
+};
+
+static char *html_encode(const char *s)
+{
+    struct dynstr d;
+
+    dynstr_init(&d);
+
+    while (*s)
+    {
+        static const struct esc
+        {
+            char c;
+            const char *str;
+        } esc[] =
+        {
+            {.c = '<', .str = "&gt;"},
+            {.c = '>', .str = "&lt;"},
+            {.c = '&', .str = "&amp;"},
+            {.c = '\"', .str = "&quot;"},
+            {.c = '\'', .str = "&apos;"}
+        };
+
+        char buf[sizeof "a"] = {0};
+        const char *str = NULL;
+
+        for (size_t i = 0; i < sizeof esc / sizeof *esc; i++)
+        {
+            const struct esc *const e = &esc[i];
+
+            if (*s == e->c)
+            {
+                str = e->str;
+                break;
+            }
+        }
+
+        if (!str)
+        {
+            *buf = *s;
+            str = buf;
+        }
+
+        if (dynstr_append(&d, "%s", str))
+        {
+            fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+            goto failure;
+        }
+
+        s++;
+    }
+
+    return d.str;
+
+failure:
+    dynstr_free(&d);
+    return NULL;
+}
+
+int html_node_set_value(struct html_node *const n, const char *const val)
+{
+    if (!(n->value = html_encode(val)))
+    {
+        fprintf(stderr, "%s: html_encode failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int html_node_set_value_unescaped(struct html_node *const n,
+    const char *const val)
+{
+    if (!(n->value = strdup(val)))
+    {
+        fprintf(stderr, "%s: strdup(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+int html_node_add_attr(struct html_node *const n, const char *const attr,
+    const char *const val)
+{
+    if (!(n->attrs = realloc(n->attrs, (n->n + 1) * sizeof *n->attrs)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    struct html_attribute *const a = &n->attrs[n->n++];
+
+    *a = (const struct html_attribute){0};
+
+    if (!(a->attr = strdup(attr))
+        || (val && !(a->value = strdup(val))))
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        free(a->attr);
+        free(a->value);
+        return -1;
+    }
+
+    return 0;
+}
+
+void html_node_add_sibling(struct html_node *const n,
+    struct html_node *const sibling)
+{
+    for (struct html_node *c = n; c; c = c->sibling)
+        if (!c->sibling)
+        {
+            c->sibling = sibling;
+            break;
+        }
+}
+
+struct html_node *html_node_add_child(struct html_node *const n,
+    const char *const element)
+{
+    struct html_node *const child = html_node_alloc(element);
+
+    if (!child)
+        return NULL;
+    else if (n->child)
+        html_node_add_sibling(n->child, child);
+    else
+        n->child = child;
+
+    return child;
+}
+
+int serialize_node(struct dynstr *const d, const struct html_node *const n,
+    const unsigned level)
+{
+    for (unsigned i = 0; i < level; i++)
+        dynstr_append(d, "\t");
+
+    dynstr_append_or_ret_nonzero(d, "<%s", n->element);
+
+    if (n->n)
+        dynstr_append_or_ret_nonzero(d, " ");
+
+    for (size_t i = 0; i < n->n; i++)
+    {
+        const struct html_attribute *const a = &n->attrs[i];
+
+        if (a->value)
+            dynstr_append_or_ret_nonzero(d, "%s=\"%s\"", a->attr, a->value);
+        else
+            dynstr_append_or_ret_nonzero(d, "%s", a->attr);
+
+        if (i + 1 < n->n)
+            dynstr_append_or_ret_nonzero(d, " ");
+    }
+
+    if (!n->value && !n->child)
+        dynstr_append_or_ret_nonzero(d, "/>");
+    else
+    {
+        dynstr_append_or_ret_nonzero(d, ">");
+
+        if (n->value)
+            dynstr_append_or_ret_nonzero(d, "%s", n->value);
+
+        if (n->child)
+        {
+            dynstr_append_or_ret_nonzero(d, "\n");
+
+            if (serialize_node(d, n->child, level + 1))
+            {
+                fprintf(stderr, "%s: serialize_node failed\n", __func__);
+                return -1;
+            }
+
+            for (unsigned i = 0; i < level; i++)
+                dynstr_append(d, "\t");
+        }
+
+        dynstr_append_or_ret_nonzero(d, "</%s>", n->element);
+    }
+
+    /* TODO: print siblings */
+
+    dynstr_append_or_ret_nonzero(d, "\n");
+
+    if (n->sibling)
+        return serialize_node(d, n->sibling, level);
+
+    return 0;
+}
+
+int html_serialize(const struct html_node *const n, struct dynstr *const d)
+{
+    return serialize_node(d, n, 0);
+}
+
+static void html_attribute_free(struct html_attribute *const a)
+{
+    if (a)
+    {
+        free(a->attr);
+        free(a->value);
+    }
+}
+
+void html_node_free(struct html_node *const n)
+{
+    if (n)
+    {
+        struct html_node *s = n->sibling;
+
+        html_node_free(n->child);
+
+        while (s)
+        {
+            struct html_node *const next = s->sibling;
+
+            html_node_free(s->child);
+            free(s->element);
+            free(s->value);
+
+            for (size_t i = 0 ; i < s->n; i++)
+                html_attribute_free(&s->attrs[i]);
+
+            free(s->attrs);
+            free(s);
+            s = next;
+        }
+
+        free(n->element);
+        free(n->value);
+
+        for (size_t i = 0 ; i < n->n; i++)
+            html_attribute_free(&n->attrs[i]);
+
+        free(n->attrs);
+    }
+
+    free(n);
+}
+
+struct html_node *html_node_alloc(const char *const element)
+{
+    struct html_node *const n = malloc(sizeof *n);
+
+    if (!n)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    *n = (const struct html_node)
+    {
+        .element = strdup(element)
+    };
+
+    if (!n->element)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    return n;
+
+failure:
+    html_node_free(n);
+    return NULL;
+}
diff --git a/html.h b/html.h
new file mode 100644
index 0000000..e62575e
--- /dev/null
+++ b/html.h
@@ -0,0 +1,15 @@
+#ifndef HTML_H
+#define HTML_H
+
+#include <dynstr.h>
+
+struct html_node *html_node_alloc(const char *element);
+void html_node_free(struct html_node *n);
+int html_node_set_value(struct html_node *n, const char *val);
+int html_node_set_value_unescaped(struct html_node *n, const char *val);
+int html_node_add_attr(struct html_node *n, const char *attr, const char *val);
+struct html_node *html_node_add_child(struct html_node *n, const char *elem);
+void html_node_add_sibling(struct html_node *n, struct html_node *sibling);
+int html_serialize(const struct html_node *n, struct dynstr *d);
+
+#endif /* HTML_H */
diff --git a/http.c b/http.c
new file mode 100644
index 0000000..629f356
--- /dev/null
+++ b/http.c
@@ -0,0 +1,1612 @@
+#include "http.h"
+#include <dynstr.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+struct http_ctx
+{
+    struct ctx
+    {
+        enum state
+        {
+            START_LINE,
+            HEADER_CR_LINE,
+            BODY_LINE
+        } state;
+
+        enum
+        {
+            LINE_CR,
+            LINE_LF
+        } lstate;
+
+        enum http_op op;
+        char *resource, *field, *value, *boundary;
+        size_t len;
+
+        struct post
+        {
+            char *path;
+            unsigned long long len, read;
+        } post;
+
+        union
+        {
+            struct start_line
+            {
+                enum
+                {
+                    START_LINE_OP,
+                    START_LINE_RESOURCE,
+                    START_LINE_PROTOCOL
+                } state;
+            } sl;
+
+            struct multiform
+            {
+                enum mf_state
+                {
+                    MF_START_BOUNDARY,
+                    MF_HEADER_CR_LINE,
+                    MF_BODY_BOUNDARY_LINE,
+                    MF_END_BOUNDARY_CR_LINE
+                } state;
+
+                enum
+                {
+                    BODY_CR,
+                    BODY_LF,
+                    BODY_DATA
+                } bstate;
+
+                off_t len, written;
+                char *boundary;
+                const char *dir;
+                size_t blen, nforms, nfiles;
+                int fd;
+                struct http_post_file *files;
+
+                struct form
+                {
+                    char *name, *filename, *tmpname, *value;
+                } *forms;
+            } mf;
+        } u;
+    } ctx;
+
+    struct write_ctx
+    {
+        bool pending;
+        enum state state;
+        struct http_response r;
+        off_t n;
+        struct dynstr d;
+    } wctx;
+
+    enum version
+    {
+        HTTP_1_0,
+        HTTP_1_1
+    } version;
+
+    /* From RFC9112, section 3 (Request line):
+     * It is RECOMMENDED that all HTTP senders and recipients support,
+     * at a minimum, request-line lengths of 8000 octets. */
+    char line[8000];
+    struct http_cfg cfg;
+};
+
+static const char *const versions[] =
+{
+    [HTTP_1_0] = "HTTP/1.0",
+    [HTTP_1_1] = "HTTP/1.1"
+};
+
+static int get_version(struct http_ctx *const h, const char *const v)
+{
+    for (enum version i = 0; i < sizeof versions / sizeof *versions; i++)
+        if (!strcmp(versions[i], v))
+        {
+            h->version = i;
+            return 0;
+        }
+
+    return -1;
+}
+
+static int start_line(struct http_ctx *const h)
+{
+    const char *const line = (const char *)h->line;
+
+    if (!*line)
+    {
+        fprintf(stderr, "%s: expected non-empty line\n", __func__);
+        return 1;
+    }
+
+    const char *const op = strchr(line, ' ');
+
+    if (!op || op == line)
+    {
+        fprintf(stderr, "%s: expected resource\n", __func__);
+        return 1;
+    }
+
+    struct ctx *const c = &h->ctx;
+    const size_t n = op - line;
+
+    if (!strncmp(line, "GET", n))
+        c->op = HTTP_OP_GET;
+    else if (!strncmp(line, "POST", n))
+        c->op = HTTP_OP_POST;
+    else
+    {
+        fprintf(stderr, "%s: unsupported HTTP op %.*s\n",
+            __func__, (int)n, line);
+        return 1;
+    }
+
+    const char *const resource = op + 1,
+        *const res_end = strchr(resource, ' ');
+
+    if (!res_end)
+    {
+        fprintf(stderr, "%s: expected protocol version\n", __func__);
+        return 1;
+    }
+
+    const size_t res_n = res_end - resource;
+
+    if (memchr(resource, '*', res_n))
+    {
+        fprintf(stderr, "%s: illegal character * in resource %.*s\n",
+            __func__, (int)res_n, resource);
+        return 1;
+    }
+
+    const char *const protocol = res_end + 1;
+
+    if (!*protocol)
+    {
+        fprintf(stderr, "%s: expected protocol version\n", __func__);
+        return 1;
+    }
+    else if (strchr(protocol, ' '))
+    {
+        fprintf(stderr, "%s: unexpected field after protocol version\n",
+            __func__);
+        return 1;
+    }
+
+    int ret = 1;
+    char *enc_res = NULL;
+
+    if (get_version(h, protocol))
+    {
+        fprintf(stderr, "%s: unsupported protocol %s\n", __func__, protocol);
+        goto end;
+    }
+    else if (!(enc_res = strndup(resource, res_n)))
+    {
+        fprintf(stderr, "%s: strndup(3): %s\n", __func__, strerror(errno));
+        ret = -1;
+        goto end;
+    }
+    else if (!(c->resource = http_decode_url(enc_res)))
+    {
+        fprintf(stderr, "%s: http_decode_url failed\n", __func__);
+        goto end;
+    }
+
+    printf("%.*s %s %s\n", (int)n, line, c->resource, protocol);
+    ret = 0;
+    c->state = HEADER_CR_LINE;
+
+end:
+    free(enc_res);
+    return ret;
+}
+
+static void ctx_free(struct ctx *const c)
+{
+    if (c->boundary)
+    {
+        struct multiform *const m = &c->u.mf;
+
+        free(m->files);
+        free(m->boundary);
+
+        for (size_t i = 0; i < m->nforms; i++)
+        {
+            struct form *const f = &m->forms[i];
+
+            free(f->name);
+            free(f->filename);
+            free(f->tmpname);
+            free(f->value);
+        }
+
+        free(m->forms);
+
+        if (m->fd >= 0 && close(m->fd))
+            fprintf(stderr, "%s: close(2) m->fd: %s\n",
+                __func__, strerror(errno));
+    }
+
+    free(c->field);
+    free(c->value);
+    free(c->resource);
+    free(c->boundary);
+
+    *c = (const struct ctx){0};
+}
+
+static int prepare_headers(struct http_ctx *const h)
+{
+    struct write_ctx *const w = &h->wctx;
+    struct dynstr *const d = &w->d;
+
+    dynstr_init(d);
+
+    for (size_t i = 0; i < w->r.n_headers; i++)
+    {
+        const struct http_header *const hdr = &w->r.headers[i];
+
+        dynstr_append_or_ret_nonzero(d, "%s: %s\r\n", hdr->header, hdr->value);
+        free(hdr->header);
+        free(hdr->value);
+    }
+
+    free(w->r.headers);
+    dynstr_append_or_ret_nonzero(d, "\r\n");
+    return 0;
+}
+
+static int rw_error(const int r, bool *const close)
+{
+    if (r < 0)
+    {
+        switch (errno)
+        {
+            case ECONNRESET:
+                *close = true;
+                return 1;
+
+            case EAGAIN:
+                return 0;
+
+            default:
+                break;
+        }
+
+        fprintf(stderr, "%s: %s\n", __func__, strerror(errno));
+        return -1;
+    }
+    else if (!r)
+    {
+        *close = true;
+        return 0;
+    }
+
+    fprintf(stderr, "%s: unexpected value %d\n", __func__, r);
+    return -1;
+}
+
+static int write_start_line(struct http_ctx *const h, bool *const close)
+{
+    struct write_ctx *const w = &h->wctx;
+    struct dynstr *const d = &w->d;
+    const size_t rem = d->len - w->n;
+    const int res = h->cfg.write(d->str + w->n, rem,
+        h->cfg.user);
+
+    if (res <= 0)
+        return rw_error(res, close);
+    else if ((w->n += res) >= d->len)
+    {
+        char len[sizeof "18446744073709551615"];
+        const int res = snprintf(len, sizeof len, "%llu", w->r.n);
+
+        dynstr_free(d);
+
+        if (res < 0 || res >= sizeof len)
+        {
+            fprintf(stderr, "%s: snprintf(3) failed\n", __func__);
+            return -1;
+        }
+        else if (http_response_add_header(&w->r, "Content-Length", len))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            return -1;
+        }
+        else if (prepare_headers(h))
+        {
+            fprintf(stderr, "%s: prepare_headers failed\n", __func__);
+            return -1;
+        }
+
+        w->state = HEADER_CR_LINE;
+        w->n = 0;
+    }
+
+    return 0;
+}
+
+static int write_ctx_free(struct write_ctx *const w)
+{
+    int ret = 0;
+    const struct http_response *const r = &w->r;
+
+    if (r->free)
+        r->free(r->buf.rw);
+
+    if (r->f && (ret = fclose(r->f)))
+        fprintf(stderr, "%s: fclose(3): %s\n", __func__, strerror(errno));
+
+    dynstr_free(&w->d);
+    *w = (const struct write_ctx){0};
+    return ret;
+}
+
+static int write_header_cr_line(struct http_ctx *const h, bool *const close)
+{
+    struct write_ctx *const w = &h->wctx;
+    struct dynstr *const d = &w->d;
+    const size_t rem = d->len - w->n;
+    const int res = h->cfg.write(d->str + w->n, rem, h->cfg.user);
+
+    if (res <= 0)
+        return rw_error(res, close);
+    else if ((w->n += res) >= d->len)
+    {
+        dynstr_free(d);
+
+        if (w->r.n)
+        {
+            w->state = BODY_LINE;
+            w->n = 0;
+        }
+        else if (write_ctx_free(w))
+        {
+            fprintf(stderr, "%s: write_ctx_free failed\n", __func__);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+static int write_body_mem(struct http_ctx *const h, bool *const close)
+{
+    struct write_ctx *const w = &h->wctx;
+    const struct http_response *const r = &w->r;
+    const size_t rem = r->n - w->n;
+    const int res = h->cfg.write((const char *)r->buf.ro + w->n, rem,
+        h->cfg.user);
+
+    if (res <= 0)
+        return rw_error(res, close);
+    else if ((w->n += res) >= r->n)
+    {
+        if (h->version == HTTP_1_0)
+            *close = true;
+
+        return write_ctx_free(w);
+    }
+
+    return 0;
+}
+
+static int write_body_file(struct http_ctx *const h, bool *const close)
+{
+    struct write_ctx *const w = &h->wctx;
+    const struct http_response *const r = &w->r;
+    const unsigned long long left = r->n - w->n;
+    char buf[1024];
+    const size_t rem = left > sizeof buf ? sizeof buf : left;
+
+    if (!fread(buf, 1, rem, r->f))
+    {
+        fprintf(stderr, "%s: fread(3) failed, ferror=%d, feof=%d\n",
+            __func__, ferror(r->f), feof(r->f));
+        return -1;
+    }
+
+    const int res = h->cfg.write(buf, rem, h->cfg.user);
+
+    if (res <= 0)
+        return rw_error(res, close);
+    else if ((w->n += res) >= r->n)
+    {
+        if (h->version == HTTP_1_0)
+            *close = true;
+
+        return write_ctx_free(w);
+    }
+
+    return 0;
+}
+
+static int write_body_line(struct http_ctx *const h, bool *const close)
+{
+    const struct http_response *const r = &h->wctx.r;
+
+    if (r->buf.ro)
+        return write_body_mem(h, close);
+    else if (r->f)
+        return write_body_file(h, close);
+
+    fprintf(stderr, "%s: expected either buffer or file path\n", __func__);
+    return -1;
+}
+
+static int http_write(struct http_ctx *const h, bool *const close)
+{
+    static int (*const fn[])(struct http_ctx *, bool *) =
+    {
+        [START_LINE] = write_start_line,
+        [HEADER_CR_LINE] = write_header_cr_line,
+        [BODY_LINE] = write_body_line,
+    };
+
+    struct write_ctx *const w = &h->wctx;
+
+    const int ret = fn[w->state](h, close);
+
+    if (ret)
+        write_ctx_free(w);
+
+    return ret;
+}
+
+int http_response_add_header(struct http_response *const r,
+    const char *const header, const char *const value)
+{
+    if (!(r->headers = realloc(r->headers,
+        sizeof (r->n_headers + 1) *sizeof *r->headers)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    struct http_header *const h = &r->headers[r->n_headers++];
+
+    *h = (const struct http_header)
+    {
+        .header = strdup(header),
+        .value = strdup(value)
+    };
+
+    if (!h->header || !h->value)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        free(h->header);
+        free(h->value);
+        free(h);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int start_response(struct http_ctx *const h)
+{
+    static const struct code
+    {
+        const char *descr;
+        int code;
+    } codes[] =
+    {
+#define X(x, y, z) [HTTP_STATUS_##x] = {.descr = y, .code = z},
+        HTTP_STATUSES
+#undef X
+    };
+
+    struct write_ctx *const w = &h->wctx;
+    const struct code *const c = &codes[w->r.status];
+
+    w->pending = true;
+    dynstr_init(&w->d);
+    dynstr_append_or_ret_nonzero(&w->d, "%s %d %s\r\n",
+        versions[h->version], c->code, c->descr);
+    return 0;
+}
+
+static int set_cookie(struct http_ctx *const h, const char *const cookie)
+{
+    struct ctx *const c = &h->ctx;
+    const char *const value = strchr(cookie, '=');
+
+    if (!value)
+    {
+        fprintf(stderr, "%s: expected field=value for cookie %s\n",
+            __func__, cookie);
+        goto failure;
+    }
+    else if (!*(value + 1))
+    {
+        fprintf(stderr, "%s: expected non-empty value for cookie %s\n",
+            __func__, cookie);
+        goto failure;
+    }
+    else if (!(c->field = strndup(cookie, value - cookie)))
+    {
+        fprintf(stderr, "%s: malloc(3) field: %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+    else if (!(c->value = strdup(value + 1)))
+    {
+        fprintf(stderr, "%s: malloc(3) value: %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    return 0;
+
+failure:
+    free(c->field);
+    free(c->value);
+    return -1;
+}
+
+static int set_length(struct http_ctx *const h, const char *const len)
+{
+    h->ctx.post.len = strtoull(len, NULL, 10);
+    return 0;
+}
+
+static int set_content_type(struct http_ctx *const h, const char *const type)
+{
+    const char *const sep = strchr(type, ';');
+
+    if (!sep)
+        /* No multipart/form-data expected. */
+        return 0;
+
+    const size_t n = sep - type;
+
+    if (strncmp(type, "multipart/form-data", n))
+    {
+        fprintf(stderr, "%s: unsupported Content-Type %.*s\n",
+            __func__, (int)n, type);
+        return 1;
+    }
+
+    const char *boundary = sep + 1;
+
+    while (*boundary == ' ')
+        boundary++;
+
+    if (!*boundary)
+    {
+        fprintf(stderr, "%s: expected boundary\n", __func__);
+        return 1;
+    }
+
+    const char *const eq = strchr(boundary, '=');
+
+    if (!eq)
+    {
+        fprintf(stderr, "%s: expected = after boundary\n", __func__);
+        return 1;
+    }
+
+    const size_t bn = eq - boundary;
+
+    if (strncmp(boundary, "boundary", bn))
+    {
+        fprintf(stderr, "%s: expected boundary, got %.*s\n",
+            __func__, (int)bn, boundary);
+        return 1;
+    }
+
+    const char *val = eq + 1;
+
+    while (*val == ' ')
+        val++;
+
+    if (!*val)
+    {
+        fprintf(stderr, "%s: expected value after boundary\n", __func__);
+        return 1;
+    }
+
+    struct ctx *const c = &h->ctx;
+    struct dynstr b;
+
+    dynstr_init(&b);
+
+    if (dynstr_append(&b, "\r\n--%s", val))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        return -1;
+    }
+
+    c->boundary = b.str;
+    c->u.mf = (const struct multiform){.fd = -1};
+    return 0;
+}
+
+static int payload_get(struct http_ctx *const h, const char *const line)
+{
+    struct ctx *const c = &h->ctx;
+    const struct http_payload p =
+    {
+        .cookie =
+        {
+            .field = c->field,
+            .value = c->value
+        },
+
+        .op = c->op,
+        .resource = c->resource
+    };
+
+    const int ret = h->cfg.payload(&p, &h->wctx.r, h->cfg.user);
+
+    ctx_free(c);
+
+    if (ret)
+        return ret;
+
+    return start_response(h);
+}
+
+static int payload_post(struct http_ctx *const h, const char *const line)
+{
+    struct ctx *const c = &h->ctx;
+    const struct http_payload pl =
+    {
+        .cookie =
+        {
+            .field = c->field,
+            .value = c->value
+        },
+
+        .op = c->op,
+        .resource = c->resource
+    };
+
+    const int ret = h->cfg.payload(&pl, &h->wctx.r, h->cfg.user);
+
+    ctx_free(c);
+
+    if (ret)
+        return ret;
+
+    return start_response(h);
+}
+
+static int get_field_value(const char *const line, size_t *const n,
+    const char **const value)
+{
+    const char *const field = strchr(line, ':');
+
+    if (!field || line == field)
+    {
+        fprintf(stderr, "%s: expected field:value\n", __func__);
+        return 1;
+    }
+
+    *n = field - line;
+    *value = field + 1;
+
+    if (!**value)
+    {
+        fprintf(stderr, "%s: expected value\n", __func__);
+        return 1;
+    }
+
+    while (**value == ' ')
+        (*value)++;
+
+    return 0;
+}
+
+static int expect(struct http_ctx *const h, const char *const value)
+{
+    if (!strcmp(value, "100-continue"))
+    {
+        struct ctx *const c = &h->ctx;
+        const struct http_payload p =
+        {
+            .u.post.expect_continue = true,
+            .cookie =
+            {
+                .field = c->field,
+                .value = c->value
+            },
+
+            .op = c->op,
+            .resource = c->resource
+        };
+
+        const int ret = h->cfg.payload(&p, &h->wctx.r, h->cfg.user);
+
+        if (ret)
+            return ret;
+
+        return start_response(h);
+    }
+
+    return 0;
+}
+
+static int process_header(struct http_ctx *const h, const char *const line,
+    const size_t n, const char *const value)
+{
+    static const struct header
+    {
+        const char *header;
+        int (*f)(struct http_ctx *, const char *);
+    } headers[] =
+    {
+        {
+            .header = "Cookie",
+            .f = set_cookie
+        },
+
+        {
+            .header = "Content-Length",
+            .f = set_length
+        },
+
+        {
+            .header = "Expect",
+            .f = expect
+        },
+
+        {
+            .header = "Content-Type",
+            .f = set_content_type
+        }
+    };
+
+    for (size_t i = 0; i < sizeof headers / sizeof *headers; i++)
+    {
+        const struct header *const hdr = &headers[i];
+        int ret;
+
+        if (!strncmp(line, hdr->header, n) && (ret = hdr->f(h, value)))
+            return ret;
+    }
+
+    return 0;
+}
+
+static int header_cr_line(struct http_ctx *const h)
+{
+    const char *const line = (const char *)h->line;
+    struct ctx *const c = &h->ctx;
+
+    if (!*line)
+    {
+        switch (c->op)
+        {
+            case HTTP_OP_GET:
+                return payload_get(h, line);
+
+            case HTTP_OP_POST:
+                if (!c->post.len)
+                    return payload_post(h, line);
+
+                c->state = BODY_LINE;
+                return 0;
+        }
+    }
+
+    const char *value;
+    size_t n;
+    const int ret = get_field_value(line, &n, &value);
+
+    if (ret)
+        return ret;
+
+    return process_header(h, line, n, value);
+}
+
+static int send_payload(struct http_ctx *const h,
+    const struct http_payload *const p)
+{
+    struct ctx *const c = &h->ctx;
+    const int ret = h->cfg.payload(p, &h->wctx.r, h->cfg.user);
+
+    ctx_free(c);
+
+    if (ret)
+        return ret;
+
+    return start_response(h);
+}
+
+static int update_lstate(struct http_ctx *const h, bool *const close,
+    int (*const f)(struct http_ctx *), const char b)
+{
+    int ret = 1;
+    struct ctx *const c = &h->ctx;
+
+    switch (c->lstate)
+    {
+        case LINE_CR:
+            if (b == '\r')
+                c->lstate = LINE_LF;
+            else if (c->len < sizeof h->line - 2)
+                h->line[c->len++] = b;
+            else
+            {
+                fprintf(stderr, "%s: line too long\n", __func__);
+                goto failure;
+            }
+
+            break;
+
+        case LINE_LF:
+            if (b == '\n')
+            {
+                h->line[c->len] = '\0';
+
+                if ((ret = f(h)))
+                    goto failure;
+
+                c->len = 0;
+            }
+            else if (c->len < sizeof h->line - 3)
+            {
+                h->line[c->len++] = '\r';
+                h->line[c->len++] = b;
+            }
+            else
+            {
+                fprintf(stderr, "%s: line too long\n", __func__);
+                goto failure;
+            }
+
+            c->lstate = LINE_CR;
+            break;
+    }
+
+    return 0;
+
+failure:
+    ctx_free(c);
+    return ret;
+}
+
+static int start_boundary_line(struct http_ctx *const h)
+{
+    struct ctx *const c = &h->ctx;
+    struct multiform *const m = &c->u.mf;
+    const char *const line = h->line;
+
+    if (strcmp(line, c->boundary + strlen("\r\n")))
+    {
+        fprintf(stderr, "%s: expected boundary %s, got %s\n",
+            __func__, c->boundary, line);
+        return 1;
+    }
+
+    m->state = MF_HEADER_CR_LINE;
+    m->len = strlen(line) + strlen("\r\n");
+    return 0;
+}
+
+static int cd_fields(struct http_ctx *const h, struct form *const f,
+    const char *sep)
+{
+    do
+    {
+        while (*++sep == ' ')
+            ;
+
+        if (!*sep)
+            break;
+
+        const char *const op = strchr(sep, '=');
+
+        if (!op)
+        {
+            fprintf(stderr, "%s: expected attr=value\n", __func__);
+            return 1;
+        }
+
+        const char *const value = op + 1, *const end = strchr(value, ';');
+        const size_t vlen = end ? end - value : strlen(value);
+
+        if (*value != '\"' || value[vlen - 1] != '\"')
+        {
+            fprintf(stderr, "%s: expected \"-enclosed value, got %.*s\n",
+                __func__, (int)vlen, value);
+            return 1;
+        }
+
+        const char *const evalue = value + 1;
+        const size_t evlen = vlen - 2;
+
+        if (!strncmp(sep, "name", op - sep))
+        {
+            if (!evlen)
+            {
+                fprintf(stderr, "%s: expected non-empty name\n", __func__);
+                return 1;
+            }
+            else if (!(f->name = strndup(evalue, evlen)))
+            {
+                fprintf(stderr, "%s: strndup(3): %s\n",
+                    __func__, strerror(errno));
+                return -1;
+            }
+        }
+        else if (!strncmp(sep, "filename", op - sep))
+        {
+            if (!evlen)
+            {
+                fprintf(stderr, "%s: expected non-empty filename\n", __func__);
+                return 1;
+            }
+            else if (!(f->filename = strndup(evalue, evlen)))
+            {
+                fprintf(stderr, "%s: strndup(3): %s\n", __func__, strerror(errno));
+                return -1;
+            }
+        }
+    } while ((sep = strchr(sep, ';')));
+
+    if (!f->name)
+    {
+        fprintf(stderr, "%s: expected name\n", __func__);
+        return 1;
+    }
+
+    return 0;
+}
+
+static int set_content_disposition(struct http_ctx *const h,
+    const char *const c)
+{
+    const char *const sep = strchr(c, ';');
+    struct multiform *const m = &h->ctx.u.mf;
+
+    if (!sep)
+    {
+        fprintf(stderr, "%s: no fields found\n", __func__);
+        return 1;
+    }
+    else if (strncmp(c, "form-data", sep - c))
+    {
+        fprintf(stderr, "%s: expected form-data, got %.*s\n",
+            __func__, (int)(sep - c), c);
+        return 1;
+    }
+    else if (!(m->forms = realloc(m->forms,
+        (m->nforms + 1) * sizeof *m->forms)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    struct form *const f = &m->forms[m->nforms++];
+
+    *f = (const struct form){0};
+    return cd_fields(h, f, sep);
+}
+
+static int mf_header_cr_line(struct http_ctx *const h)
+{
+    struct ctx *const c = &h->ctx;
+    struct multiform *const m = &c->u.mf;
+    const char *const line = h->line;
+
+    m->len += strlen(line) + strlen("\r\n");
+
+    if (!*line)
+    {
+        const size_t n = strlen("\r\n") + strlen(c->boundary) + 1;
+
+        if (!m->boundary && !(m->boundary = calloc(1, n)))
+        {
+            fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+            return -1;
+        }
+
+        m->state = MF_BODY_BOUNDARY_LINE;
+        return 0;
+    }
+
+    const char *value;
+    size_t n;
+    int ret = get_field_value(line, &n, &value);
+
+    if (ret)
+        return ret;
+    else if (!strncmp(line, "Content-Disposition", n)
+        && (ret = set_content_disposition(h, value)))
+        return ret;
+
+    return 0;
+}
+
+static int end_boundary_line(struct http_ctx *const h)
+{
+    const char *const line = h->line;
+
+    if (!*line)
+    {
+        h->ctx.u.mf.state = MF_HEADER_CR_LINE;
+        return 0;
+    }
+    else if (!strcmp(line, "--"))
+    {
+        /* Found end boundary. */
+        struct ctx *const c = &h->ctx;
+        struct multiform *const m = &c->u.mf;
+
+        const struct http_payload p =
+        {
+            .cookie =
+            {
+                .field = c->field,
+                .value = c->value
+            },
+
+            .op = c->op,
+            .resource = c->resource,
+            .u.post =
+            {
+                .dir = m->dir,
+                .files = m->files,
+                .n = m->nfiles
+            }
+        };
+
+        return send_payload(h, &p);
+    }
+
+    fprintf(stderr, "%s: unexpected line after boundary: %s\n",
+        __func__, line);
+    return 1;
+}
+
+static int process_mf_line(struct http_ctx *const h)
+{
+    static int (*const state[])(struct http_ctx *) =
+    {
+        [MF_START_BOUNDARY] = start_boundary_line,
+        [MF_HEADER_CR_LINE] = mf_header_cr_line,
+        [MF_END_BOUNDARY_CR_LINE] = end_boundary_line
+    };
+
+    h->ctx.post.read += strlen(h->line) + strlen("\r\n");
+    return state[h->ctx.u.mf.state](h);
+}
+
+static char *get_tmp(const char *const tmpdir)
+{
+    struct dynstr d;
+
+    dynstr_init(&d);
+
+    if (dynstr_append(&d, "%s/tmp.XXXXXX", tmpdir))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        return NULL;
+    }
+
+    return d.str;
+}
+
+static int generate_mf_file(struct http_ctx *const h)
+{
+    struct multiform *const m = &h->ctx.u.mf;
+    struct form *const f = &m->forms[m->nforms - 1];
+
+    if (!(f->tmpname = get_tmp(h->cfg.tmpdir)))
+    {
+        fprintf(stderr, "%s: get_tmp failed\n", __func__);
+        return -1;
+    }
+    else if ((m->fd = mkstemp(f->tmpname)) < 0)
+    {
+        fprintf(stderr, "%s: mkstemp(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+static int read_mf_body_to_mem(struct http_ctx *const h, const void *const buf,
+    const size_t n)
+{
+    struct ctx *const c = &h->ctx;
+    struct multiform *const m = &c->u.mf;
+
+    if (m->written + n > sizeof h->line)
+    {
+        fprintf(stderr, "%s: maximum length exceeded\n", __func__);
+        return 1;
+    }
+
+    memcpy(&h->line[m->written], buf, n);
+    m->written += n;
+    m->len += n;
+    c->post.read += n;
+    return 0;
+}
+
+static int read_mf_body_to_file(struct http_ctx *const h, const void *const buf,
+    const size_t n)
+{
+    struct ctx *const c = &h->ctx;
+    struct multiform *const m = &c->u.mf;
+    ssize_t res;
+
+    if (m->fd < 0 && generate_mf_file(h))
+    {
+        fprintf(stderr, "%s: generate_mf_file failed\n", __func__);
+        return -1;
+    }
+    else if ((res = pwrite(m->fd, buf, n, m->written)) < 0)
+    {
+        fprintf(stderr, "%s: pwrite(2): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    m->written += res;
+    m->len += res;
+    c->post.read += res;
+    return 0;
+}
+
+static int reset_boundary(struct http_ctx *const h, const void *const buf,
+    const size_t n)
+{
+    struct multiform *const m = &h->ctx.u.mf;
+    struct form *const f = &m->forms[m->nforms - 1];
+    const size_t len = strlen(m->boundary);
+    int (*const read_mf)(struct http_ctx *, const void *, size_t) =
+        f->filename ? read_mf_body_to_file : read_mf_body_to_mem;
+    const int res = read_mf(h, m->boundary, len);
+
+    if (res)
+        return res;
+
+    memset(m->boundary, '\0', len);
+    m->blen = 0;
+    return read_mf(h, buf, n);
+}
+
+static int apply_from_file(struct http_ctx *const h, struct form *const f)
+{
+    struct multiform *const m = &h->ctx.u.mf;
+
+    if (close(m->fd))
+    {
+        fprintf(stderr, "%s: close(2): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    m->fd = -1;
+
+    if (!(m->files = realloc(m->files, (m->nfiles + 1) * sizeof *m->files)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    struct http_post_file *const pf = &m->files[m->nfiles++];
+
+    *pf = (const struct http_post_file)
+    {
+        .tmpname = f->tmpname,
+        .filename = f->filename
+    };
+
+    return 0;
+}
+
+static int apply_from_mem(struct http_ctx *const h, struct form *const f)
+{
+    struct multiform *const m = &h->ctx.u.mf;
+
+    if (!(f->value = strndup(h->line, m->written)))
+    {
+        fprintf(stderr, "%s: strndup(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+    else if (!strcmp(f->name, "dir"))
+    {
+        if (m->dir)
+        {
+            fprintf(stderr, "%s: \"dir\" defined more than once\n", __func__);
+            return 1;
+        }
+
+        m->dir = f->value;
+    }
+
+    return 0;
+}
+
+static int read_mf_body_boundary_byte(struct http_ctx *const h, const char b,
+    const size_t len)
+{
+    struct ctx *const c = &h->ctx;
+    struct multiform *const m = &c->u.mf;
+
+    if (b == c->boundary[m->blen])
+    {
+        m->boundary[len] = b;
+
+        if (++m->blen >= strlen(c->boundary))
+        {
+            /* Found intermediate boundary. */
+            struct form *const f = &m->forms[m->nforms - 1];
+            const int ret = f->filename ? apply_from_file(h, f)
+                : apply_from_mem(h, f);
+
+            memset(m->boundary, '\0', len + 1);
+            m->blen = 0;
+            m->state = MF_END_BOUNDARY_CR_LINE;
+            m->written = 0;
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
+/* Similar to memmem(3), provided here to avoid the use of GNU extensions. */
+static const char *http_memmem(const char *const a, const void *const b,
+    const size_t n)
+{
+    const size_t len = strlen(a);
+
+    if (len > n)
+        return NULL;
+
+    const char *s = a, *st = NULL;
+
+    for (size_t i = 0; i < n; i++)
+    {
+        const char *bc = b;
+        const char c = bc[i];
+
+        if (*s == c)
+        {
+            if (!st)
+                st = &bc[i];
+
+            if (!*++s)
+                return st;
+        }
+        else if (*(s = a) != c)
+            st = NULL;
+        else
+        {
+            st = &bc[i];
+
+            if (!*++s)
+                return st;
+        }
+    }
+
+    return NULL;
+}
+
+static int read_mf_body_boundary(struct http_ctx *const h,
+    const char **const buf, size_t *const n)
+{
+    struct ctx *const c = &h->ctx;
+    struct multiform *const m = &c->u.mf;
+    const char *const boundary = http_memmem(&c->boundary[m->blen], *buf, *n);
+    int res;
+
+    if (!boundary)
+    {
+        if ((res = reset_boundary(h, *buf, *n)))
+            return res;
+
+        *n = 0;
+        return 0;
+    }
+
+    const size_t prev = boundary - *buf;
+
+    if ((res = reset_boundary(h, *buf, prev)))
+        return res;
+
+    *buf += prev;
+    *n -= prev;
+
+    const size_t len = strlen(m->boundary),
+        rem = strlen(c->boundary) - len,
+        r = rem > *n ? *n : rem;
+
+    for (size_t i = 0; i < r; i++)
+    {
+        const char *const b = *buf;
+
+        if ((res = read_mf_body_boundary_byte(h, b[i], len)))
+            return res;
+    }
+
+    *buf += r;
+    *n -= r;
+    return 0;
+}
+
+static int read_multiform_n(struct http_ctx *const h, bool *const close,
+    const char *buf, size_t n)
+{
+    struct multiform *const m = &h->ctx.u.mf;
+
+    while (n)
+    {
+        int res;
+
+        switch (m->state)
+        {
+            case MF_START_BOUNDARY:
+                /* Fall through. */
+            case MF_HEADER_CR_LINE:
+                /* Fall through. */
+            case MF_END_BOUNDARY_CR_LINE:
+            {
+                if ((res = update_lstate(h, close, process_mf_line, *buf)))
+                    return res;
+
+                buf++;
+                n--;
+            }
+
+                break;
+
+            case MF_BODY_BOUNDARY_LINE:
+                if ((res = read_mf_body_boundary(h, &buf, &n)))
+                    return res;
+        }
+    }
+
+    return 0;
+}
+
+static int read_multiform(struct http_ctx *const h, bool *const close)
+{
+    /* Note: the larger the buffer below, the less CPU load. */
+    char buf[sizeof h->line];
+    struct post *const p = &h->ctx.post;
+    const unsigned long long left = p->len - p->read;
+    const size_t rem = left > sizeof buf ? sizeof buf : left;
+    const int r = h->cfg.read(buf, rem, h->cfg.user);
+
+    if (r <= 0)
+        return rw_error(r, close);
+
+    return read_multiform_n(h, close, buf, r);
+}
+
+static int read_body_to_mem(struct http_ctx *const h, bool *const close)
+{
+    char b;
+    const int r = h->cfg.read(&b, sizeof b, h->cfg.user);
+
+    if (r <= 0)
+        return rw_error(r, close);
+
+    struct ctx *const c = &h->ctx;
+    struct post *const p = &c->post;
+
+    if (p->read >= sizeof h->line)
+    {
+        fprintf(stderr, "%s: exceeded maximum length\n", __func__);
+        return 1;
+    }
+
+    h->line[p->read++] = b;
+
+    if (p->read >= p->len)
+    {
+        const struct http_payload pl =
+        {
+            .cookie =
+            {
+                .field = c->field,
+                .value = c->value
+            },
+
+            .op = c->op,
+            .resource = c->resource,
+            .u.post =
+            {
+                .data = h->line,
+                .n = p->len
+            }
+        };
+
+        return send_payload(h, &pl);
+    }
+
+    return 0;
+}
+
+static int read_body(struct http_ctx *const h, bool *const close)
+{
+    return h->ctx.boundary ? read_multiform(h, close)
+        : read_body_to_mem(h, close);
+}
+
+static int process_line(struct http_ctx *const h)
+{
+    static int (*const state[])(struct http_ctx *) =
+    {
+        [START_LINE] = start_line,
+        [HEADER_CR_LINE] = header_cr_line
+    };
+
+    return state[h->ctx.state](h);
+}
+
+static int http_read(struct http_ctx *const h, bool *const close)
+{
+    switch (h->ctx.state)
+    {
+        case START_LINE:
+            /* Fall through. */
+        case HEADER_CR_LINE:
+        {
+            char b;
+            const int r = h->cfg.read(&b, sizeof b, h->cfg.user);
+
+            if (r <= 0)
+                return rw_error(r, close);
+
+            return update_lstate(h, close, process_line, b);
+        }
+
+        case BODY_LINE:
+            return read_body(h, close);
+    }
+
+    fprintf(stderr, "%s: unexpected state %d\n", __func__, h->ctx.state);
+    return -1;
+}
+
+char *http_cookie_create(const char *const key, const char *const value)
+{
+    struct dynstr d;
+
+    dynstr_init(&d);
+    dynstr_append_or_ret_null(&d, "%s=%s; HttpOnly", key, value);
+    return d.str;
+}
+
+int http_update(struct http_ctx *const h, bool *const write, bool *const close)
+{
+    *close = false;
+
+    struct write_ctx *const w = &h->wctx;
+    const int ret = w->pending ? http_write(h, close) : http_read(h, close);
+
+    *write = w->pending;
+    return ret;
+}
+
+void http_free(struct http_ctx *const h)
+{
+    if (h)
+    {
+        ctx_free(&h->ctx);
+        write_ctx_free(&h->wctx);
+    }
+
+    free(h);
+}
+
+struct http_ctx *http_alloc(const struct http_cfg *const cfg)
+{
+    struct http_ctx *const h = malloc(sizeof *h);
+
+    if (!h)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    *h = (const struct http_ctx)
+    {
+        .cfg = *cfg
+    };
+
+    return h;
+
+failure:
+    http_free(h);
+    return NULL;
+}
+
+char *http_encode_url(const char *url)
+{
+    struct dynstr d;
+    char c;
+
+    dynstr_init(&d);
+
+    while ((c = *url++))
+    {
+        /* Unreserved characters must not be percent-encoded. */
+        if ((c >= 'A' && c <= 'Z')
+            || (c >= 'a' && c <= 'z')
+            || (c == '-')
+            || (c == '_')
+            || (c == '.')
+            || (c == '/')
+            || (c == '~'))
+        {
+            if (dynstr_append(&d, "%c", c))
+            {
+                fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+                goto failure;
+            }
+        }
+        else if (dynstr_append(&d, "%%%hhx", c))
+        {
+            fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+            goto failure;
+        }
+    }
+
+    return d.str;
+
+failure:
+    dynstr_free(&d);
+    return NULL;
+}
+
+char *http_decode_url(const char *url)
+{
+    char *ret = NULL;
+    size_t n = 0;
+
+    while (*url)
+    {
+        if (!(ret = realloc(ret, n + 1)))
+        {
+            fprintf(stderr, "%s: realloc(3) loop: %s\n",
+                __func__, strerror(errno));
+            goto failure;
+        }
+        else if (*url != '%')
+            ret[n++] = *url++;
+        else if (*(url + 1) && *(url + 2))
+        {
+            const char buf[sizeof "00"] = {*(url + 1), *(url + 2)};
+
+            ret[n++] = strtoul(buf, NULL, 16);
+            url += 3;
+        }
+        else
+        {
+            fprintf(stderr, "%s: unterminated %%\n", __func__);
+            goto failure;
+        }
+    }
+
+    if (!(ret = realloc(ret, n + 1)))
+    {
+        fprintf(stderr, "%s: realloc(3) end: %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    ret[n] = '\0';
+    return ret;
+
+failure:
+    free(ret);
+    return NULL;
+}
diff --git a/http.h b/http.h
new file mode 100644
index 0000000..3390e49
--- /dev/null
+++ b/http.h
@@ -0,0 +1,96 @@
+#ifndef HTTP_H
+#define HTTP_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+
+struct http_payload
+{
+    enum http_op
+    {
+        HTTP_OP_GET,
+        HTTP_OP_POST
+    } op;
+
+    const char *resource;
+
+    struct http_cookie
+    {
+        const char *field, *value;
+    } cookie;
+
+    union
+    {
+        struct http_post
+        {
+            bool expect_continue;
+            const void *data;
+            size_t n;
+            const char *dir;
+
+            const struct http_post_file
+            {
+                const char *tmpname, *filename;
+            } *files;
+        } post;
+    } u;
+};
+
+#define HTTP_STATUSES \
+    X(CONTINUE, "Continue", 100) \
+    X(OK, "OK", 200) \
+    X(SEE_OTHER, "See other", 303) \
+    X(BAD_REQUEST, "Bad Request", 400) \
+    X(UNAUTHORIZED, "Unauthorized", 401) \
+    X(FORBIDDEN, "Forbidden", 403) \
+    X(NOT_FOUND, "Not found", 404) \
+    X(INTERNAL_ERROR, "Internal Server Error", 500)
+
+struct http_response
+{
+    enum http_status
+    {
+#define X(x, y, z) HTTP_STATUS_##x,
+        HTTP_STATUSES
+#undef X
+    } status;
+
+    struct http_header
+    {
+        char *header, *value;
+    } *headers;
+
+    union
+    {
+        const void *ro;
+        void *rw;
+    } buf;
+
+    FILE *f;
+    unsigned long long n;
+    size_t n_headers;
+    void (*free)(void *);
+};
+
+struct http_cfg
+{
+    int (*read)(void *buf , size_t n, void *user);
+    int (*write)(const void *buf, size_t n, void *user);
+    int (*payload)(const struct http_payload *p, struct http_response *r,
+        void *user);
+    const char *tmpdir;
+    void *user;
+};
+
+struct http_ctx *http_alloc(const struct http_cfg *cfg);
+void http_free(struct http_ctx *h);
+/* Positive return value: user input error, negative: fatal error. */
+int http_update(struct http_ctx *h, bool *write, bool *close);
+int http_response_add_header(struct http_response *r, const char *header,
+    const char *value);
+char *http_cookie_create(const char *key, const char *value);
+char *http_encode_url(const char *url);
+char *http_decode_url(const char *url);
+
+#endif /* HTTP_H */
diff --git a/jwt.c b/jwt.c
new file mode 100644
index 0000000..2587b91
--- /dev/null
+++ b/jwt.c
@@ -0,0 +1,147 @@
+#include "jwt.h"
+#include "base64.h"
+#include <dynstr.h>
+#include <cjson/cJSON.h>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+#include <openssl/sha.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+static const char jwt_header[] = "{\"alg\": \"HS256\", \"typ\": \"JWT\"}";
+
+static char *get_payload(const char *const name)
+{
+    char *ret = NULL;
+    struct dynstr d;
+
+    dynstr_init(&d);
+
+    if (dynstr_append(&d, "{\"name\": \"%s\"}", name))
+    {
+        fprintf(stderr, "%s: dynstr_append name failed\n", __func__);
+        goto end;
+    }
+    else if (!(ret = base64_encode(d.str, d.len)))
+    {
+        fprintf(stderr, "%s: base64 failed\n", __func__);
+        goto end;
+    }
+
+end:
+    dynstr_free(&d);
+    return ret;
+}
+
+static char *get_hmac(const void *const buf, const size_t n,
+    const void *const key, const size_t keyn)
+{
+    unsigned char hmac[SHA256_DIGEST_LENGTH];
+    const EVP_MD *const md = EVP_sha256();
+    char *ret = NULL;
+
+    if (!md)
+    {
+        fprintf(stderr, "%s: EVP_sha256 failed\n", __func__);
+        return NULL;
+    }
+    else if (!HMAC(md, key, keyn, buf, n, hmac, NULL))
+    {
+        fprintf(stderr, "%s: HMAC failed\n", __func__);
+        return NULL;
+    }
+    else if (!(ret = base64_encode(hmac, sizeof hmac)))
+    {
+        fprintf(stderr, "%s: base64 failed\n", __func__);
+        return NULL;
+    }
+
+    return ret;
+}
+
+char *jwt_encode(const char *const name, const void *const key, const size_t n)
+{
+    char *ret = NULL;
+    char *const header = base64_encode(jwt_header, strlen(jwt_header)),
+        *const payload = get_payload(name),
+        *hmac = NULL;
+    struct dynstr jwt;
+
+    dynstr_init(&jwt);
+
+    if (!header)
+    {
+        fprintf(stderr, "%s: base64_encode header failed\n", __func__);
+        goto end;
+    }
+    else if (!payload)
+    {
+        fprintf(stderr, "%s: get_payload failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&jwt, "%s.%s", header, payload))
+    {
+        fprintf(stderr, "%s: dynstr_append header+payload failed", __func__);
+        goto end;
+    }
+    else if (!(hmac = get_hmac(jwt.str, jwt.len, key, n)))
+    {
+        fprintf(stderr, "%s: get_hmac failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&jwt, ".%s", hmac))
+    {
+        fprintf(stderr, "%s: dynstr_append hmac failed\n", __func__);
+        goto end;
+    }
+
+    ret = jwt.str;
+
+end:
+    free(header);
+    free(payload);
+    free(hmac);
+
+    if (!ret)
+        dynstr_free(&jwt);
+
+    return ret;
+}
+
+int jwt_check(const char *const jwt, const void *const key, const size_t n)
+{
+    const char *const p = strrchr(jwt, '.');
+    const EVP_MD *const md = EVP_sha256();
+    unsigned char hmac[SHA256_DIGEST_LENGTH];
+    char *dhmac = NULL;
+    size_t hmaclen;
+
+    if (!md)
+    {
+        fprintf(stderr, "%s: EVP_sha256 failed\n", __func__);
+        return -1;
+    }
+    else if (!p)
+    {
+        fprintf(stderr, "%s: expected '.'\n", __func__);
+        return 1;
+    }
+    else if (!HMAC(md, key, n, (const unsigned char *)jwt, p - jwt, hmac, NULL))
+    {
+        fprintf(stderr, "%s: HMAC failed\n", __func__);
+        return -1;
+    }
+    else if (!(dhmac = base64_decode(p + 1, &hmaclen)))
+    {
+        fprintf(stderr, "%s: base64_decode failed\n", __func__);
+        return -1;
+    }
+
+    const int r = memcmp(dhmac, hmac, hmaclen);
+
+    free(dhmac);
+    return !!r;
+}
diff --git a/jwt.h b/jwt.h
new file mode 100644
index 0000000..d8db4a8
--- /dev/null
+++ b/jwt.h
@@ -0,0 +1,9 @@
+#ifndef JWT_H
+#define JWT_H
+
+#include <stddef.h>
+
+char *jwt_encode(const char *name, const void *key, size_t n);
+int jwt_check(const char *jwt, const void *key, size_t n);
+
+#endif /* JWT_H */
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..2ebf655
--- /dev/null
+++ b/main.c
@@ -0,0 +1,935 @@
+#include "auth.h"
+#include "handler.h"
+#include "http.h"
+#include "page.h"
+#include <dynstr.h>
+#include <libgen.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct form
+{
+    char *key, *value;
+};
+
+static int redirect(struct http_response *const r)
+{
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_SEE_OTHER
+    };
+
+    if (http_response_add_header(r, "Location", "/user/"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int serve_index(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    struct auth *const a = user;
+
+    if (auth_cookie(a, &p->cookie))
+        return page_login(r);
+
+    return redirect(r);
+}
+
+static int serve_style(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    return page_style(r);
+}
+
+static char *alloc_form_data(const char *const s, const char **const end)
+{
+    const char *const next = strchr(s, '&');
+    const size_t len = next ? next - s : strlen(s);
+    char *const data = malloc(len + 1);
+
+    if (!data)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        return NULL;
+    }
+
+    memcpy(data, s, len);
+    data[len] = '\0';
+    *end = s + len;
+
+    if (next)
+        *end += 1;
+
+    return data;
+}
+
+static struct form *append_form(struct form *forms, const char **const s,
+    size_t *const n)
+{
+    struct form *ret = NULL;
+    const char *end;
+    char *const data = alloc_form_data(*s, &end), *key = NULL, *value = NULL;
+    struct form *f = NULL;
+
+    if (!data)
+    {
+        fprintf(stderr, "%s: alloc_form_data failed\n", __func__);
+        goto end;
+    }
+    else if (!(forms = realloc(forms, (*n + 1) * sizeof *forms)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+
+    const char *const sep = strchr(data, '=');
+
+    if (!sep)
+    {
+        fprintf(stderr, "%s: strchr(3) returned NULL\n", __func__);
+        goto end;
+    }
+    else if (!data || !*(sep + 1))
+    {
+        fprintf(stderr, "%s: expected key=value (%s)\n", __func__, data);
+        goto end;
+    }
+
+    f = &forms[(*n)++];
+
+    const size_t keylen = sep - data;
+
+    if (!(key = strndup(data, keylen)))
+    {
+        fprintf(stderr, "%s: strndup(3) key: %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (!(value = strdup(sep + 1)))
+    {
+        fprintf(stderr, "%s: strdup(3) value: %s\n", __func__, strerror(errno));
+        goto end;
+    }
+
+    *f = (const struct form)
+    {
+        .key = http_decode_url(key),
+        .value = http_decode_url(value)
+    };
+
+    if (!f->key || !f->value)
+    {
+        fprintf(stderr, "%s: http_decode_url key/value failed\n", __func__);
+        goto end;
+    }
+
+    *s = end;
+    ret = forms;
+
+end:
+    free(key);
+    free(value);
+    free(data);
+
+    if (!ret)
+    {
+        if (f)
+        {
+            free(f->key);
+            free(f->value);
+        }
+
+        return NULL;
+    }
+
+    return ret;
+}
+
+static struct form *get_forms(const struct http_payload *const pl,
+    size_t *const outn)
+{
+    const struct http_post *const p = &pl->u.post;
+    const char *const ref = p->data;
+    char *dup = NULL;
+    struct form *forms = NULL;
+
+    if (!ref)
+    {
+        fprintf(stderr, "%s: expected non-NULL buffer\n", __func__);
+        goto failure;
+    }
+    else if (!(dup = strndup(ref, p->n)))
+    {
+        fprintf(stderr, "%s: strndup(3): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    const char *s = dup;
+
+    *outn = 0;
+
+    while (*s)
+        if (!(forms = append_form(forms, &s, outn)))
+        {
+            fprintf(stderr, "%s: append_form failed\n", __func__);
+            goto failure;
+        }
+
+    free(dup);
+    return forms;
+
+failure:
+    free(dup);
+    free(forms);
+    return NULL;
+}
+
+static int check_credentials(struct auth *const a,
+    const struct form *const forms, const size_t n, char **const cookie)
+{
+    const char *username = NULL, *pwd = NULL;
+
+    *cookie = NULL;
+
+    for (size_t i = 0; i < n; i++)
+    {
+        const struct form *const f = &forms[i];
+
+        if (!strcmp(f->key, "username"))
+            username = f->value;
+        else if (!strcmp(f->key, "password"))
+            pwd = f->value;
+    }
+
+    if (!username || !pwd)
+    {
+        fprintf(stderr, "%s: missing credentials\n", __func__);
+        return 1;
+    }
+
+    const int ret = auth_login(a, username, pwd, cookie);
+
+    if (ret < 0)
+        fprintf(stderr, "%s: auth_login failed\n", __func__);
+
+    return ret;
+}
+
+static int login(const struct http_payload *const pl,
+    struct http_response *const r, void *const user)
+{
+    int res = -1;
+    size_t n;
+    struct form *const forms = get_forms(pl, &n);
+    struct auth *const a = user;
+    char *cookie = NULL;
+
+    if (!forms)
+    {
+        fprintf(stderr, "%s: get_forms failed\n", __func__);
+        goto end;
+    }
+    else if ((res = check_credentials(a, forms, n, &cookie)))
+    {
+        if (res < 0)
+            fprintf(stderr, "%s: check_credentials failed\n", __func__);
+
+        goto end;
+    }
+    else if (redirect(r))
+    {
+        fprintf(stderr, "%s: redirect failed\n", __func__);
+        goto end;
+    }
+    else if (cookie && http_response_add_header(r, "Set-Cookie", cookie))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        goto end;
+    }
+
+    res = 0;
+
+end:
+    if (forms)
+        for (size_t i = 0; i < n; i++)
+        {
+            free(forms[i].key);
+            free(forms[i].value);
+        }
+
+    free(cookie);
+    free(forms);
+
+    if (res)
+    {
+        if (page_failed_login(r))
+        {
+            fprintf(stderr, "%s: page_failed_login failed\n", __func__);
+            return -1;
+        }
+        else if (http_response_add_header(r, "Location", "/"))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            return -1;
+        }
+        else if (http_response_add_header(r, "Content-Type", "text/html"))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+static int logout(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    struct auth *const a = user;
+    const struct http_cookie *const c = &p->cookie;
+    const int res = auth_cookie(a, c);
+
+    if (res < 0)
+    {
+        fprintf(stderr, "%s: auth_cookie failed\n", __func__);
+        return -1;
+    }
+    else if (res)
+        return page_forbidden(r);
+
+    int ret = -1;
+    struct dynstr d;
+    static const char date[] = "Thu, 1 Jan 1970 00:00:00 GMT";
+
+    dynstr_init(&d);
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_SEE_OTHER
+    };
+
+    if (http_response_add_header(r, "Location", "/"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        goto end;
+    }
+    else if (http_response_add_header(r, "Content-Type", "text/html"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        goto end;
+    }
+    /* Force expired cookie so they are removed by the browser, too. */
+    else if (dynstr_append(&d, "%s=%s; Expires=%s", c->field, c->value, date))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+    else if (http_response_add_header(r, "Set-Cookie", d.str))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    dynstr_free(&d);
+    return ret;
+}
+
+static int search(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    struct auth *const a = user;
+
+    if (auth_cookie(a, &p->cookie))
+    {
+        fprintf(stderr, "%s: auth_cookie failed\n", __func__);
+        return page_forbidden(r);
+    }
+
+    fprintf(stderr, "%s: TODO\n", __func__);
+    return -1;
+}
+
+static bool path_isrel(const char *const path)
+{
+    if (!strcmp(path, "..") || !strcmp(path, ".") || strstr(path, "/../"))
+        return true;
+
+    static const char suffix[] = "/..";
+    const size_t n = strlen(path), sn = strlen(suffix);
+
+    if (n >= sn && !strcmp(path + n - sn, suffix))
+        return true;
+
+    return false;
+}
+
+static char *cust_dirname(char *const d)
+{
+    /*
+        path       dirname   cust_dirname
+        /usr/lib   /usr      /usr/
+        /usr/      /         /usr/
+        usr        .         .
+        /          /         /
+        .          .         .
+        ..         .         .
+    */
+
+    if (!strcmp(d, "."))
+        return d;
+
+    char *const s = strrchr(d, '/');
+
+    if (!s)
+        return ".";
+
+    *(s + 1) = '\0';
+    return d;
+}
+
+static int getnode(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    struct auth *const a = user;
+
+    if (auth_cookie(a, &p->cookie))
+    {
+        fprintf(stderr, "%s: auth_cookie failed\n", __func__);
+
+        *r = (const struct http_response)
+        {
+            .status = HTTP_STATUS_SEE_OTHER
+        };
+
+        if (http_response_add_header(r, "Location", "/"))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            return -1;
+        }
+        else if (http_response_add_header(r, "Content-Type", "text/html"))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            return -1;
+        }
+
+        return 0;
+    }
+
+    const char *const username = p->cookie.field,
+        *const resource = p->resource + strlen("/user/");
+
+    if (path_isrel(resource))
+    {
+        fprintf(stderr, "%s: illegal relative path %s\n", __func__, resource);
+        return page_forbidden(r);
+    }
+
+    int ret = -1;
+    struct dynstr root, d;
+    char *const dird = strdup(p->resource), *dir = NULL;
+    const char *const adir = auth_dir(a);
+
+    dynstr_init(&d);
+    dynstr_init(&root);
+
+    if (!adir)
+    {
+        fprintf(stderr, "%s: auth_dir failed\n", __func__);
+        goto end;
+    }
+    else if (!dird)
+    {
+        fprintf(stderr, "%s: strdup(3) failed: %s\n",
+            __func__, strerror(errno));
+        goto end;
+    }
+    else if (!(dir = cust_dirname(dird)))
+    {
+        fprintf(stderr, "%s: dirname(3) failed: %s\n",
+            __func__, strerror(errno));
+        goto end;
+    }
+    else if (dynstr_append(&root, "%s/user/%s/", adir, username)
+        || dynstr_append(&d, "%s%s", root.str, resource))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+
+    ret = page_resource(r, dir, root.str, d.str);
+
+end:
+    dynstr_free(&d);
+    dynstr_free(&root);
+    free(dird);
+    return ret;
+}
+
+static int move_file(const char *const old, const char *const new)
+{
+    int ret = -1;
+    FILE *const f = fopen(old, "rb");
+    const int fd = open(new, O_WRONLY | O_CREAT, 0600);
+    struct stat sb;
+
+    if (!f)
+    {
+        fprintf(stderr, "%s: fopen(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (fd < 0)
+    {
+        fprintf(stderr, "%s: open(2): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (stat(old, &sb))
+    {
+        fprintf(stderr, "%s: stat(2): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+
+    for (off_t i = 0; i < sb.st_size;)
+    {
+        char buf[1024];
+        const off_t left = sb.st_size - i;
+        const size_t rem = left > sizeof buf ? sizeof buf : left;
+        ssize_t w;
+
+        if (!fread(buf, rem, 1, f))
+        {
+            fprintf(stderr, "%s: fread(3) failed, feof=%d, ferror=%d\n",
+                __func__, feof(f), ferror(f));
+            goto end;
+        }
+        else if ((w = write(fd, buf, rem)) < 0)
+        {
+            fprintf(stderr, "%s: write(2): %s\n", __func__, strerror(errno));
+            goto end;
+        }
+        else if (w != rem)
+        {
+            fprintf(stderr, "%s: write(2): expected to write %zu bytes, "
+                "only %ju written\n", __func__, rem, (intmax_t)w);
+            goto end;
+        }
+
+        i += rem;
+    }
+
+    ret = 0;
+
+end:
+    if (fd >= 0 && close(fd))
+    {
+        fprintf(stderr, "%s: close(2): %s\n", __func__, strerror(errno));
+        ret = -1;
+    }
+
+    if (f && fclose(f))
+    {
+        fprintf(stderr, "%s: fclose(3): %s\n", __func__, strerror(errno));
+        ret = -1;
+    }
+    else if (remove(old))
+    {
+        fprintf(stderr, "%s: remove(3): %s\n", __func__, strerror(errno));
+        ret = -1;
+    }
+
+    return ret;
+}
+
+static int rename_or_move(const char *const old, const char *const new)
+{
+    const int res = rename(old, new);
+
+    if (res && errno == EXDEV)
+        return move_file(old, new);
+    else if (res)
+        fprintf(stderr, "%s: rename(3): %s\n", __func__, strerror(errno));
+
+    return res;
+}
+
+static int upload_file(const struct http_post_file *const f,
+    const char *const user, const char *const root, const char *const dir)
+{
+    int ret = -1;
+    struct dynstr d;
+
+    dynstr_init(&d);
+
+    if (!root)
+    {
+        fprintf(stderr, "%s: auth_dir failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&d, "%s/user/%s/%s%s", root, user, dir, f->filename))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+    else if (rename_or_move(f->tmpname, d.str))
+    {
+        fprintf(stderr, "%s: rename_or_move failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    dynstr_free(&d);
+    return ret;
+}
+
+static int redirect_to_dir(const char *const dir,
+    struct http_response *const r)
+{
+    int ret = -1;
+    struct dynstr d;
+    char *const encdir = http_encode_url(dir);
+
+    dynstr_init(&d);
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_SEE_OTHER
+    };
+
+    if (!encdir)
+    {
+        fprintf(stderr, "%s: http_encode_url failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&d, "/user%s", encdir))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+    else if (http_response_add_header(r, "Location", d.str))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    free(encdir);
+    dynstr_free(&d);
+    return ret;
+}
+
+static int upload_files(const struct http_payload *const p,
+    struct http_response *const r, const struct auth *const a)
+{
+    const struct http_post *const po = &p->u.post;
+    const char *const root = auth_dir(a), *const user = p->cookie.field,
+        *const dir = po->dir;
+
+    if (!po->files)
+    {
+        fprintf(stderr, "%s: expected file list\n", __func__);
+        return 1;
+    }
+    else if (!root)
+    {
+        fprintf(stderr, "%s: auth_dir failed\n", __func__);
+        return -1;
+    }
+    else if (!dir)
+    {
+        static const char body[] = "<html>No target directory set</html>";
+
+        *r = (const struct http_response)
+        {
+            .status = HTTP_STATUS_BAD_REQUEST,
+            .buf.ro = body,
+            .n = strlen(body)
+        };
+
+        if (http_response_add_header(r, "Content-Type", "text/html"))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            return -1;
+        }
+
+        return 0;
+    }
+
+    for (size_t i = 0; i < po->n; i++)
+    {
+        if (upload_file(&po->files[i], user, root, po->dir))
+        {
+            fprintf(stderr, "%s: upload_file failed\n", __func__);
+            return -1;
+        }
+    }
+
+    return redirect_to_dir(dir, r);
+}
+
+static int upload(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    const struct auth *const a = user;
+
+    if (auth_cookie(a, &p->cookie))
+    {
+        fprintf(stderr, "%s: auth_cookie failed\n", __func__);
+        return page_forbidden(r);
+    }
+    else if (p->u.post.expect_continue)
+    {
+        *r = (const struct http_response)
+        {
+            .status = HTTP_STATUS_CONTINUE
+        };
+
+        return 0;
+    }
+
+    return upload_files(p, r, a);
+}
+
+static int createdir(const struct http_payload *const p,
+    struct http_response *const r, void *const user)
+{
+    struct auth *const a = user;
+
+    if (auth_cookie(a, &p->cookie))
+    {
+        fprintf(stderr, "%s: auth_cookie failed\n", __func__);
+        return page_forbidden(r);
+    }
+
+    size_t n;
+    struct form *const forms = get_forms(p, &n);
+
+    if (!forms)
+    {
+        fprintf(stderr, "%s: get_forms failed\n", __func__);
+        return page_bad_request(r);
+    }
+    else if (n != 2)
+    {
+        fprintf(stderr, "%s: expected 2 forms, got %zu\n", __func__, n);
+        return page_bad_request(r);
+    }
+
+    char *name = NULL;
+    const char *dir = NULL;
+
+    for (size_t i = 0; i < n; i++)
+    {
+        const struct form *const f = &forms[i];
+
+        if (!strcmp(f->key, "name"))
+            name = f->value;
+        else if (!strcmp(f->key, "dir"))
+            dir = f->value;
+        else
+        {
+            fprintf(stderr, "%s: unexpected key %s\n", __func__, f->key);
+            return page_bad_request(r);
+        }
+    }
+
+    if (!name || !dir)
+    {
+        fprintf(stderr, "%s: missing name or directory\n", __func__);
+        return page_bad_request(r);
+    }
+    else if (path_isrel(name) || strpbrk(name, "/*"))
+    {
+        fprintf(stderr, "%s: invalid directory name %s\n", __func__, dir);
+        return page_bad_request(r);
+    }
+    else if (path_isrel(dir) || strchr(dir, '*'))
+    {
+        fprintf(stderr, "%s: invalid name %s\n", __func__, name);
+        return page_bad_request(r);
+    }
+
+    /* HTML input forms use '+' for whitespace, rather than %20. */
+    {
+        char *c = name;
+
+        while ((c = strchr(c, '+')))
+            *c = ' ';
+    }
+
+    const char *const root = auth_dir(a);
+
+    if (!root)
+    {
+        fprintf(stderr, "%s: auth_dir failed\n", __func__);
+        return -1;
+    }
+
+    int ret = -1;
+    struct dynstr d, userd;
+
+    dynstr_init(&d);
+    dynstr_init(&userd);
+
+    if (dynstr_append(&d, "%s/user/%s/%s%s", root, p->cookie.field, dir, name))
+    {
+        fprintf(stderr, "%s: dynstr_append d failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&userd, "/user%s%s/", dir, name))
+    {
+        fprintf(stderr, "%s: dynstr_append userd failed\n", __func__);
+        goto end;
+    }
+    else if (mkdir(d.str, 0700))
+    {
+        fprintf(stderr, "%s: mkdir(2): %s\n", __func__, strerror(errno));
+
+        if (errno != EEXIST)
+            goto end;
+        else
+        {
+            static const char body[] = "<html>Directory already exists</html>";
+
+            *r = (const struct http_response)
+            {
+                .status = HTTP_STATUS_BAD_REQUEST,
+                .buf.ro = body,
+                .n = strlen(body)
+            };
+
+            if (http_response_add_header(r, "Content-Type", "text/html"))
+            {
+                fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+                return -1;
+            }
+        }
+    }
+    else
+    {
+        *r = (const struct http_response)
+        {
+            .status = HTTP_STATUS_SEE_OTHER
+        };
+
+        if (http_response_add_header(r, "Location", userd.str))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            goto end;
+        }
+        else if (http_response_add_header(r, "Content-Type", "text/html"))
+        {
+            fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+            return -1;
+        }
+    }
+
+    ret = 0;
+
+end:
+    dynstr_free(&userd);
+    dynstr_free(&d);
+    return ret;
+}
+
+static void usage(char *const argv[])
+{
+    fprintf(stderr, "%s [-t tmpdir] [-p port] dir\n", *argv);
+}
+
+static int parse_args(const int argc, char *const argv[],
+    const char **const dir, unsigned short *const port,
+    const char **const tmpdir)
+{
+    const char *const envtmp = getenv("TMPDIR");
+    int opt;
+
+    /* Default values. */
+    *port = 0;
+    *tmpdir = envtmp ? envtmp : "/tmp";
+
+    while ((opt = getopt(argc, argv, "t:p:")) != -1)
+    {
+        switch (opt)
+        {
+            case 't':
+                *tmpdir = optarg;
+                break;
+
+            case 'p':
+            {
+                const unsigned long portul = strtoul(optarg, NULL, 10);
+
+                if (portul > UINT16_MAX)
+                {
+                    fprintf(stderr, "%s: invalid port %lu\n", __func__, portul);
+                    return -1;
+                }
+
+                *port = portul;
+            }
+                break;
+
+            default:
+                usage(argv);
+                return -1;
+        }
+    }
+
+    if (optind >= argc)
+    {
+        usage(argv);
+        return -1;
+    }
+
+    *dir = argv[optind];
+    return 0;
+}
+
+int main(const int argc, char *const argv[])
+{
+    int ret = EXIT_FAILURE;
+    struct handler *h = NULL;
+    struct auth *a = NULL;
+    const char *dir, *tmpdir;
+    unsigned short port;
+
+    if (parse_args(argc, argv, &dir, &port, &tmpdir)
+        || !(a = auth_alloc(dir))
+        || !(h = handler_alloc(tmpdir))
+        || handler_add(h, "/", HTTP_OP_GET, serve_index, a)
+        || handler_add(h, "/index.html", HTTP_OP_GET, serve_index, a)
+        || handler_add(h, "/style.css", HTTP_OP_GET, serve_style, NULL)
+        || handler_add(h, "/user/*", HTTP_OP_GET, getnode, a)
+        || handler_add(h, "/login", HTTP_OP_POST, login, a)
+        || handler_add(h, "/logout", HTTP_OP_POST, logout, a)
+        || handler_add(h, "/search", HTTP_OP_POST, search, a)
+        || handler_add(h, "/upload", HTTP_OP_POST, upload, a)
+        || handler_add(h, "/mkdir", HTTP_OP_POST, createdir, a)
+        || handler_listen(h, port))
+        goto end;
+
+    ret = EXIT_SUCCESS;
+
+end:
+    auth_free(a);
+    handler_free(h);
+    return ret;
+}
diff --git a/page.c b/page.c
new file mode 100644
index 0000000..9d52769
--- /dev/null
+++ b/page.c
@@ -0,0 +1,832 @@
+#include "page.h"
+#include "http.h"
+#include "html.h"
+#include <dynstr.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#define PROJECT_TITLE "<title>slcl, a suckless cloud</title>"
+#define DOCTYPE_TAG "<!DOCTYPE html>\n"
+#define PROJECT_NAME "slcl"
+#define PROJECT_URL "https://gitea.privatedns.org/Xavi92/" PROJECT_NAME
+#define LOGIN_HEAD \
+    "   <meta charset=\"UTF-8\">\n" \
+    "   <meta name=\"viewport\"\n" \
+    "       content=\"width=device-width, initial-scale=1,\n" \
+    "           maximum-scale=1\">\n" \
+        PROJECT_TITLE "\n"
+#define STYLE_A "<link href=\"/style.css\" rel=\"stylesheet\">"
+#define LOGIN_BODY \
+    "<header>\n" \
+    "   <a href=\"" PROJECT_URL "\">" PROJECT_NAME "</a>, a suckless cloud\n" \
+    "</header>\n" \
+    "   <form action=\"/login\" method=\"post\">\n" \
+    "       <label for=\"username\">Username:</label>\n" \
+    "       <input type=\"text\" class=\"form-control\"\n" \
+    "           id=\"username\" name=\"username\" autofocus><br>\n" \
+    "       <label for=\"username\">Password:</label>\n" \
+    "       <input type=\"password\" class=\"form-control\" \n" \
+    "           id=\"password\" name=\"password\"><br>\n" \
+    "       <input type=\"submit\" value=\"Submit\">\n" \
+    "   </form>\n"
+
+static void free_response(void *const arg)
+{
+    free(arg);
+}
+
+static int prepare_name(struct html_node *const n, struct stat *const sb,
+    const char *const dir, const char *const name)
+{
+    int ret = -1;
+    struct html_node *a;
+    struct dynstr d, dname;
+    const char *const sep = S_ISDIR(sb->st_mode) ? "/" : "";
+
+    dynstr_init(&d);
+    dynstr_init(&dname);
+
+    if (dynstr_append(&d, "%s%s%s", dir, name, sep))
+    {
+        fprintf(stderr, "%s: dynstr_append [1] failed\n", __func__);
+        goto end;
+    }
+    else if (!(a = html_node_add_child(n, "a")))
+    {
+        fprintf(stderr, "%s: html_node_add_child failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_add_attr(a, "href", d.str))
+    {
+        fprintf(stderr, "%s: html_node_add_attr href failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&dname, "%s%s", name, sep))
+    {
+        fprintf(stderr, "%s: dynstr_append [2] failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_set_value(a, dname.str))
+    {
+        fprintf(stderr, "%s: html_node_set_value failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    dynstr_free(&d);
+    dynstr_free(&dname);
+    return ret;
+}
+
+static int prepare_size(struct html_node *const n, const struct stat *const sb)
+{
+    if (!S_ISREG(sb->st_mode))
+        return 0;
+
+    float sz;
+    size_t suffix_i;
+
+    for (sz = sb->st_size, suffix_i = 0; (off_t)sz / 1024;
+        suffix_i++, sz /= 1024.0f)
+        ;
+
+    static const char *const suffixes[] = {"B", "KiB", "MiB", "GiB", "TiB"};
+
+    char buf[sizeof "18446744073709551615.0 XiB"];
+    const int r = suffix_i ?
+        snprintf(buf, sizeof buf, "%.1f %s", sz, suffixes[suffix_i])
+        : snprintf(buf, sizeof buf, "%ju %s",
+            (uintmax_t)sb->st_size, suffixes[suffix_i]);
+
+    if (r >= sizeof buf || r < 0)
+    {
+        fprintf(stderr, "%s: snprintf(3) failed with %d\n", __func__, r);
+        return -1;
+    }
+    else if (html_node_set_value(n, buf))
+    {
+        fprintf(stderr, "%s: html_node_set_value failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int prepare_date(struct html_node *const n, const struct stat *const sb)
+{
+    struct tm tm;
+
+    if (!localtime_r(&sb->st_mtime, &tm))
+    {
+        fprintf(stderr, "%s: localtime_r(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    char date[sizeof "0000-00-00T00:00:00+0000"];
+
+    if (!strftime(date, sizeof date, "%Y-%m-%dT%H:%M:%S%z", &tm))
+    {
+        fprintf(stderr, "%s: strftime(3) failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_set_value(n, date))
+    {
+        fprintf(stderr, "%s: html_node_set_value failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int add_element(struct html_node *const n, const char *const dir,
+    const char *const res, const char *const name)
+{
+    int ret = -1;
+    enum {NAME, SIZE, DATE, COLUMNS};
+    struct html_node *tr, *td[COLUMNS];
+    struct dynstr path;
+    const char *const sep = res[strlen(res) - 1] != '/' ? "/" : "";
+
+    dynstr_init(&path);
+
+    if (dynstr_append(&path, "%s%s%s", res, sep, name))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+    else if (!(tr = html_node_add_child(n, "tr")))
+    {
+        fprintf(stderr, "%s: html_node_add_child tr failed\n", __func__);
+        goto end;
+    }
+
+    for (size_t i = 0; i < sizeof td / sizeof *td; i++)
+        if (!(td[i] = html_node_add_child(tr, "td")))
+        {
+            fprintf(stderr, "%s: html_node_add_child td[%zu] failed\n",
+                __func__, i);
+            goto end;
+        }
+
+    struct stat sb;
+
+    if (stat(path.str, &sb))
+    {
+        fprintf(stderr, "%s: stat(2) %s: %s\n",
+            __func__, path.str, strerror(errno));
+        goto end;
+    }
+    else if (prepare_name(td[NAME], &sb, dir, name))
+    {
+        fprintf(stderr, "%s: prepare_name failed\n", __func__);
+        goto end;
+    }
+    else if (prepare_size(td[SIZE], &sb))
+    {
+        fprintf(stderr, "%s: prepare_size failed\n", __func__);
+        goto end;
+    }
+    else if (prepare_date(td[DATE], &sb))
+    {
+        fprintf(stderr, "%s: prepare_date failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    dynstr_free(&path);
+    return ret;
+}
+
+static int prepare_upload_form(struct html_node *const n, const char *const dir)
+{
+    struct html_node *div, *hidden, *form, *submit, *input;
+
+    if (!(div = html_node_add_child(n, "div")))
+    {
+        fprintf(stderr, "%s: html_node_add_child div failed\n", __func__);
+        return -1;
+    }
+    else if (!(form = html_node_add_child(div, "form")))
+    {
+        fprintf(stderr, "%s: html_node_add_child form failed\n", __func__);
+        return -1;
+    }
+    else if (!(hidden = html_node_add_child(form, "input")))
+    {
+        fprintf(stderr, "%s: html_node_add_child hidden failed\n", __func__);
+        return -1;
+    }
+    else if (!(input = html_node_add_child(form, "input")))
+    {
+        fprintf(stderr, "%s: html_node_add_child input failed\n", __func__);
+        return -1;
+    }
+    else if (!(submit = html_node_add_child(form, "input")))
+    {
+        fprintf(stderr, "%s: html_node_add_child submit failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(form, "method", "post"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr method failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(form, "action", "/upload"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr method failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(form, "enctype", "multipart/form-data"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr enctype failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(hidden, "type", "hidden"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr hidden failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(hidden, "name", "dir"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr dir failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(hidden, "value", dir))
+    {
+        fprintf(stderr, "%s: html_node_add_attr hidden value failed\n",
+            __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(submit, "type", "submit"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr submit failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(submit, "value", "Upload file"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr value failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(input, "type", "file"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr file failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(input, "name", "file"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr name failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(input, "multiple", NULL))
+    {
+        fprintf(stderr, "%s: html_node_add_attr multiple failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int prepare_mkdir_form(struct html_node *const n, const char *const dir)
+{
+    struct html_node *div, *form, *hidden, *submit, *input;
+
+    if (!(div = html_node_add_child(n, "div")))
+    {
+        fprintf(stderr, "%s: html_node_add_child div failed\n", __func__);
+        return -1;
+    }
+    else if (!(form = html_node_add_child(div, "form")))
+    {
+        fprintf(stderr, "%s: html_node_add_child form failed\n", __func__);
+        return -1;
+    }
+    else if (!(input = html_node_add_child(form, "input")))
+    {
+        fprintf(stderr, "%s: html_node_add_child input failed\n", __func__);
+        return -1;
+    }
+    else if (!(hidden = html_node_add_child(form, "input")))
+    {
+        fprintf(stderr, "%s: html_node_add_child hidden failed\n", __func__);
+        return -1;
+    }
+    else if (!(submit = html_node_add_child(form, "input")))
+    {
+        fprintf(stderr, "%s: html_node_add_child submit failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(form, "method", "post"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr method failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(form, "action", "/mkdir"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr method failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(hidden, "type", "hidden"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr hidden failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(hidden, "name", "dir"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr dir failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(hidden, "value", dir))
+    {
+        fprintf(stderr, "%s: html_node_add_attr hidden value failed\n",
+            __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(submit, "type", "submit"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr submit failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(submit, "value", "Create directory"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr submit value failed\n",
+            __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(input, "type", "text"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr text failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(input, "name", "name"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr name failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int prepare_logout_form(struct html_node *const n)
+{
+    struct html_node *div, *form, *input;
+
+    if (!(div = html_node_add_child(n, "div")))
+    {
+        fprintf(stderr, "%s: html_node_add_child div failed\n", __func__);
+        return -1;
+    }
+    else if (!(form = html_node_add_child(div, "form")))
+    {
+        fprintf(stderr, "%s: html_node_add_child form failed\n", __func__);
+        return -1;
+    }
+    else if (!(input = html_node_add_child(form, "input")))
+    {
+        fprintf(stderr, "%s: html_node_add_child input failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(form, "method", "post"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr method failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(form, "action", "/logout"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr action failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(input, "type", "submit"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr type failed\n", __func__);
+        return -1;
+    }
+    else if (html_node_add_attr(input, "value", "Logout"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr value failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int prepare_footer(struct html_node *const n)
+{
+    int ret = -1;
+    struct html_node *footer, *const a = html_node_alloc("a");
+    struct dynstr d;
+
+    dynstr_init(&d);
+
+    if (!a)
+    {
+        fprintf(stderr, "%s: html_node_alloc failed\n", __func__);
+        goto end;
+    }
+    else if (!(footer = html_node_add_child(n, "footer")))
+    {
+        fprintf(stderr, "%s: html_node_add_child footer failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_add_attr(a, "href", PROJECT_URL))
+    {
+        fprintf(stderr, "%s: html_node_add_attr failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_set_value(a, PROJECT_NAME))
+    {
+        fprintf(stderr, "%s: html_node_set_value a failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&d, "Powered by "))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+    else if (html_serialize(a, &d))
+    {
+        fprintf(stderr, "%s: html_serialize failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_set_value_unescaped(footer, d.str))
+    {
+        fprintf(stderr, "%s: html_node_add_child a failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    dynstr_free(&d);
+    html_node_free(a);
+    return ret;
+}
+
+static int list_dir(struct http_response *const r, const char *const dir,
+    const char *const root, const char *const res)
+{
+    int ret = -1;
+    DIR *const d = opendir(res);
+    struct html_node *const html = html_node_alloc("html"),
+        *head, *title, *body, *charset, *viewport, *table;
+    struct dynstr out, t;
+    const char *const fdir = dir + strlen("/user");
+
+    dynstr_init(&out);
+    dynstr_init(&t);
+
+    if (!d)
+    {
+        fprintf(stderr, "%s: opendir(2): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (!html)
+    {
+        fprintf(stderr, "%s: html_node_alloc_failed\n", __func__);
+        goto end;
+    }
+    else if (!(head = html_node_add_child(html, "head")))
+    {
+        fprintf(stderr, "%s: html_node_add_child head failed\n", __func__);
+        goto end;
+    }
+    else if (!(body = html_node_add_child(html, "body")))
+    {
+        fprintf(stderr, "%s: html_node_add_child body failed\n", __func__);
+        goto end;
+    }
+    else if (!(table = html_node_add_child(body, "table")))
+    {
+        fprintf(stderr, "%s: html_node_add_child table failed\n", __func__);
+        goto end;
+    }
+    else if (!(title = html_node_add_child(head, "title")))
+    {
+        fprintf(stderr, "%s: html_node_add_child title failed\n", __func__);
+        goto end;
+    }
+    else if (!(charset = html_node_add_child(head, "meta")))
+    {
+        fprintf(stderr, "%s: html_node_add_child charset failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_add_attr(charset, "charset", "UTF-8"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr charset failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&t, PROJECT_NAME " - %s", fdir))
+    {
+        fprintf(stderr, "%s: dynstr_append title failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_set_value(title, t.str))
+    {
+        fprintf(stderr, "%s: html_node_set_value title failed\n", __func__);
+        goto end;
+    }
+    else if (!(viewport = html_node_add_child(head, "meta")))
+    {
+        fprintf(stderr, "%s: html_node_add_child viewport failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_add_attr(viewport, "name", "viewport"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr name viewport failed\n",
+            __func__);
+        goto end;
+    }
+    else if (html_node_add_attr(viewport, "content",
+        "width=device-width, initial-scale=1, maximum-scale=1"))
+    {
+        fprintf(stderr, "%s: html_node_add_attr name viewport failed\n",
+            __func__);
+        goto end;
+    }
+    else if (prepare_upload_form(body, fdir))
+    {
+        fprintf(stderr, "%s: prepare_upload_form failed\n", __func__);
+        goto end;
+    }
+    else if (prepare_mkdir_form(body, fdir))
+    {
+        fprintf(stderr, "%s: prepare_upload_form failed\n", __func__);
+        goto end;
+    }
+    else if (prepare_logout_form(body))
+    {
+        fprintf(stderr, "%s: prepare_logout_form failed\n", __func__);
+        goto end;
+    }
+    else if (prepare_footer(body))
+    {
+        fprintf(stderr, "%s: prepare_footer failed\n", __func__);
+        goto end;
+    }
+
+    struct dirent *de;
+
+    while ((de = readdir(d)))
+    {
+        const char *const name = de->d_name;
+
+        if (!strcmp(name, ".")
+            || (!strcmp(name, "..") && !strcmp(root, res)))
+            continue;
+        else if (add_element(table, dir, res, name))
+        {
+            fprintf(stderr, "%s: add_element failed\n", __func__);
+            goto end;
+        }
+    }
+
+    if (dynstr_append(&out, DOCTYPE_TAG))
+    {
+        fprintf(stderr, "%s: dynstr_prepend failed\n", __func__);
+        goto end;
+    }
+    else if (html_serialize(html, &out))
+    {
+        fprintf(stderr, "%s: html_serialize failed\n", __func__);
+        goto end;
+    }
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_OK,
+        .buf.rw = out.str,
+        .n = out.len,
+        .free = free_response
+    };
+
+    if (http_response_add_header(r, "Content-Type", "text/html"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    html_node_free(html);
+    dynstr_free(&t);
+
+    if (ret)
+        dynstr_free(&out);
+
+    if (closedir(d))
+    {
+        fprintf(stderr, "%s: closedir(2): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    return ret;
+}
+
+static int serve_file(struct http_response *const r,
+    const struct stat *const sb, const char *const res)
+{
+    FILE *const f = fopen(res, "rb");
+
+    if (!f)
+    {
+        fprintf(stderr, "%s: fopen(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_OK,
+        .f = f,
+        .n = sb->st_size
+    };
+
+    return 0;
+}
+
+int page_resource(struct http_response *const r, const char *const dir,
+    const char *const root, const char *const res)
+{
+    struct stat sb;
+
+    if (stat(res, &sb))
+    {
+        fprintf(stderr, "%s: stat(2) %s: %s\n",
+            __func__, res, strerror(errno));
+
+        if (errno == ENOENT)
+        {
+            *r = (const struct http_response)
+            {
+                .status = HTTP_STATUS_NOT_FOUND
+            };
+
+            return 0;
+        }
+        else
+            return -1;
+    }
+
+    const mode_t m = sb.st_mode;
+
+    if (S_ISDIR(m))
+        return list_dir(r, dir, root, res);
+    else if (S_ISREG(m))
+        return serve_file(r, &sb, res);
+
+    fprintf(stderr, "%s: unexpected st_mode %jd\n", __func__, (intmax_t)m);
+    return -1;
+}
+
+int page_failed_login(struct http_response *const r)
+{
+    static const char index[] =
+        DOCTYPE_TAG
+        "<html>\n"
+        "   <head>\n"
+        "       " LOGIN_HEAD "\n"
+        "       " STYLE_A "\n"
+        "   </head>\n"
+        "   <p>Invalid username or password.</p>\n"
+            LOGIN_BODY
+        "</html>\n";
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_UNAUTHORIZED,
+        .buf.ro = index,
+        .n = sizeof index - 1
+    };
+
+    if (http_response_add_header(r, "Content-Type", "text/html"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int page_login(struct http_response *const r)
+{
+    static const char index[] =
+        DOCTYPE_TAG
+        "<html>\n"
+        "   <head>\n"
+        "       " STYLE_A "\n"
+        "       " LOGIN_HEAD "\n"
+        "   </head>\n"
+        "   " LOGIN_BODY "\n"
+        "</html>\n";
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_OK,
+        .buf.ro = index,
+        .n = sizeof index - 1
+    };
+
+    if (http_response_add_header(r, "Content-Type", "text/html"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int page_forbidden(struct http_response *const r)
+{
+    static const char body[] =
+        DOCTYPE_TAG
+        "<html>\n"
+            "Forbidden\n"
+        "</html>";
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_FORBIDDEN,
+        .buf.ro = body,
+        .n = sizeof body - 1
+    };
+
+    if (http_response_add_header(r, "Content-Type", "text/html"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int page_bad_request(struct http_response *const r)
+{
+    static const char body[] =
+        DOCTYPE_TAG
+        "<html>\n"
+        "   <head>"
+        "   " PROJECT_TITLE "\n"
+        "   </head>"
+            "Invalid request\n"
+        "</html>";
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_BAD_REQUEST,
+        .buf.ro = body,
+        .n = sizeof body - 1
+    };
+
+    if (http_response_add_header(r, "Content-Type", "text/html"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int page_style(struct http_response *const r)
+{
+    static const char body[] =
+    "body"
+    "{\n"
+    "   display: flex;\n"
+    "   flex-direction: column;\n"
+    "}\n"
+    ".form-control\n"
+    "{\n"
+    "    display: block;\n"
+    "    border: 1px solid;\n"
+    "    width: 60%;\n"
+    "    border-radius: 8px;\n"
+    "    align-content: center;\n"
+    "}\n";
+
+    *r = (const struct http_response)
+    {
+        .status = HTTP_STATUS_OK,
+        .buf.ro = body,
+        .n = sizeof body - 1
+    };
+
+    if (http_response_add_header(r, "Content-Type", "text/css"))
+    {
+        fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
diff --git a/page.h b/page.h
new file mode 100644
index 0000000..9743556
--- /dev/null
+++ b/page.h
@@ -0,0 +1,14 @@
+#ifndef PAGE_H
+#define PAGE_H
+
+#include "http.h"
+
+int page_login(struct http_response *r);
+int page_style(struct http_response *r);
+int page_failed_login(struct http_response *r);
+int page_forbidden(struct http_response *r);
+int page_bad_request(struct http_response *r);
+int page_resource(struct http_response *r, const char *dir, const char *root,
+    const char *res);
+
+#endif /* PAGE_H */
diff --git a/server.c b/server.c
new file mode 100644
index 0000000..d867b59
--- /dev/null
+++ b/server.c
@@ -0,0 +1,303 @@
+#include "server.h"
+#include <fcntl.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct server
+{
+    int fd;
+
+    struct server_client
+    {
+        int fd;
+        bool write;
+    } *c;
+
+    size_t n;
+};
+
+int server_close(struct server *const s)
+{
+    int ret = 0;
+
+    if (!s)
+        return 0;
+    else if (s->fd >= 0)
+        ret = close(s->fd);
+
+    free(s);
+    return ret;
+}
+
+int server_client_close(struct server *const s, struct server_client *const c)
+{
+    int ret = 0;
+
+    for (size_t i = 0; i < s->n; i++)
+    {
+        struct server_client *ref = &s->c[i];
+
+        if (c == ref)
+        {
+            if ((ret = close(c->fd)))
+            {
+                fprintf(stderr, "%s: close(2): %s\n",
+                    __func__, strerror(errno));
+                return -1;
+            }
+            else if (s->n - 1)
+            {
+                memcpy(ref, ref + 1, s->n - i);
+
+                if (!(s->c = realloc(s->c, (s->n - 1) * sizeof *s->c)))
+                {
+                    fprintf(stderr, "%s: realloc(3): %s\n",
+                        __func__, strerror(errno));
+                    return -1;
+                }
+            }
+            else
+            {
+                free(s->c);
+                s->c = NULL;
+            }
+
+            s->n--;
+            break;
+        }
+    }
+
+    return ret;
+}
+
+int server_read(void *const buf, const size_t n, struct server_client *const c)
+{
+    const ssize_t r = read(c->fd, buf, n);
+
+    if (r < 0)
+        fprintf(stderr, "%s: read(2): %s\n", __func__, strerror(errno));
+
+    return r;
+}
+
+int server_write(const void *const buf, const size_t n,
+    struct server_client *const c)
+{
+    const ssize_t w = write(c->fd, buf, n);
+
+    if (w < 0)
+        fprintf(stderr, "%s: write(2): %s\n", __func__, strerror(errno));
+
+    return w;
+}
+
+static struct server_client *alloc_client(struct server *const s)
+{
+    struct sockaddr_in addr;
+    socklen_t sz = sizeof addr;
+    const int fd = accept(s->fd, (struct sockaddr *)&addr, &sz);
+
+    if (fd < 0)
+    {
+        fprintf(stderr, "%s: accept(2): %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+
+    const int flags = fcntl(fd, F_GETFL);
+
+    if (flags < 0)
+    {
+        fprintf(stderr, "%s: fcntl(2) F_GETFL: %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+    else if (fcntl(fd, F_SETFL, flags | O_NONBLOCK))
+    {
+        fprintf(stderr, "%s: fcntl(2) F_SETFL: %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+    else if (!(s->c = realloc(s->c, (s->n + 1) * sizeof *s->c)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+
+    s->c[s->n] = (const struct server_client)
+    {
+        .fd = fd
+    };
+
+    return &s->c[s->n++];
+}
+
+void server_client_write_pending(struct server_client *const c,
+    const bool write)
+{
+    c->write = write;
+}
+
+static volatile sig_atomic_t do_exit;
+
+static void handle_signal(const int signum)
+{
+    do_exit = 1;
+}
+
+struct server_client *server_select(struct server *const s, bool *const io,
+    bool *const exit)
+{
+    int nfds = -1;
+    fd_set rfds, wfds;
+
+    *io = *exit = false;
+
+    FD_ZERO(&rfds);
+    FD_ZERO(&wfds);
+
+    for (size_t i = 0; i < s->n; i++)
+    {
+        const struct server_client *const c = &s->c[i];
+        const int fd = c->fd;
+
+        FD_SET(fd, &rfds);
+
+        if (c->write)
+            FD_SET(fd, &wfds);
+
+        if (fd > nfds)
+            nfds = fd;
+    }
+
+    FD_SET(s->fd, &rfds);
+
+    if (s->fd > nfds)
+        nfds = s->fd;
+
+    const int res = select(nfds + 1, &rfds, &wfds, NULL, NULL);
+
+    if (res < 0)
+    {
+        if (do_exit)
+            *exit = true;
+        else
+            fprintf(stderr, "%s: select(2): %s\n", __func__, strerror(errno));
+
+        return NULL;
+    }
+    else if (FD_ISSET(s->fd, &rfds))
+        return alloc_client(s);
+
+    for (size_t i = 0; i < s->n; i++)
+    {
+        struct server_client *const c = &s->c[i];
+
+        if (FD_ISSET(c->fd, &rfds) || FD_ISSET(c->fd, &wfds))
+        {
+            *io = true;
+            return c;
+        }
+    }
+
+    fprintf(stderr, "%s: unlisted fd\n", __func__);
+    return NULL;
+}
+
+static int init_signals(void)
+{
+    struct sigaction sa =
+    {
+        .sa_handler = handle_signal,
+        .sa_flags = SA_RESTART
+    };
+
+    sigemptyset(&sa.sa_mask);
+
+    if (sigaction(SIGINT, &sa, NULL))
+    {
+        fprintf(stderr, "%s: sigaction(2) SIGINT: %s\n",
+            __func__, strerror(errno));
+        return -1;
+    }
+    else if (sigaction(SIGTERM, &sa, NULL))
+    {
+        fprintf(stderr, "%s: sigaction(2) SIGINT: %s\n",
+            __func__, strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+struct server *server_init(const unsigned short port)
+{
+    struct server *const s = malloc(sizeof *s);
+
+    if (!s)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    *s = (const struct server)
+    {
+        .fd = socket(AF_INET, SOCK_STREAM, 0)
+    };
+
+    if (s->fd < 0)
+    {
+        fprintf(stderr, "%s: socket(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+    else if (init_signals())
+    {
+        fprintf(stderr, "%s: init_signals failed\n", __func__);
+        goto failure;
+    }
+
+    const struct sockaddr_in addr =
+    {
+        .sin_family = AF_INET,
+        .sin_port = htons(port)
+    };
+
+    enum {QUEUE_LEN = 10};
+
+    if (bind(s->fd, (const struct sockaddr *)&addr, sizeof addr))
+    {
+        fprintf(stderr, "%s: bind(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+    else if (listen(s->fd, QUEUE_LEN))
+    {
+        fprintf(stderr, "%s: listen(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    struct sockaddr_in in;
+    socklen_t sz = sizeof in;
+
+    if (getsockname(s->fd, (struct sockaddr *)&in, &sz))
+    {
+        fprintf(stderr, "%s: getsockname(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    printf("Listening on port %hu\n", ntohs(in.sin_port));
+    return s;
+
+failure:
+    server_close(s);
+    return NULL;
+}
diff --git a/server.h b/server.h
new file mode 100644
index 0000000..74189db
--- /dev/null
+++ b/server.h
@@ -0,0 +1,15 @@
+#ifndef SERVER_H
+#define SERVER_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct server *server_init(unsigned short port);
+struct server_client *server_select(struct server *s, bool *io, bool *exit);
+int server_read(void *buf, size_t n, struct server_client *c);
+int server_write(const void *buf, size_t n, struct server_client *c);
+int server_close(struct server *s);
+int server_client_close(struct server *s, struct server_client *c);
+void server_client_write_pending(struct server_client *c, bool write);
+
+#endif /* SERVER_H */