Send HTTP headers to payload callback

Even if libweb already parses some common headers, such as
Content-Length, some users might find it interesting to inspect which
headers were received from a request.

Since HTTP/1.1 does not define a limit on the number of maximum headers
a client can send, for security reasons a maximum value must be provided
by the user. Any extra headers shall be then discarded by libweb.

An example application showing this new feature is also provided.

2 files changed, 23 insertions, 4 deletions

diff --git a/doc/man7/libweb_handler.7 b/doc/man7/libweb_handler.7
index 5c910e0..b9fd53f 100644
--- a/doc/man7/libweb_handler.7
+++ b/doc/man7/libweb_handler.7
@@ -1,4 +1,4 @@
-.TH LIBWEB_HANDLER 7 2023-09-15 0.1.0 "libweb Library Reference"
+.TH LIBWEB_HANDLER 7 2023-11-18 0.2.0 "libweb Library Reference"
 
 .SH NAME
 libweb_handler \- libweb high-level website configuration
@@ -69,15 +69,17 @@ struct handler_cfg
     const char *\fItmpdir\fP;
     int (*\fIlength\fP)(unsigned long long len, const struct http_cookie *c, struct http_response *r, void *user);
     void *\fIuser\fP;
+    size_t \fImax_headers\fP;
 };
 .EE
 .in
 .PP
 
 .IR tmpdir ,
-.I length
-and
+.IR length ,
 .I user
+and
+.I max_headers
 are passed directly to the
 .I struct http_cfg
 object used to initialize a
diff --git a/doc/man7/libweb_http.7 b/doc/man7/libweb_http.7
index 329a616..93bb882 100644
--- a/doc/man7/libweb_http.7
+++ b/doc/man7/libweb_http.7
@@ -1,4 +1,4 @@
-.TH LIBWEB_HTTP 7 2023-09-15 0.1.0 "libweb Library Reference"
+.TH LIBWEB_HTTP 7 2023-11-18 0.2.0 "libweb Library Reference"
 
 .SH NAME
 libweb_http \- libweb HTTP connection handling and utilities
@@ -84,6 +84,7 @@ struct http_cfg
     int (*\fIlength\fP)(unsigned long long \fIlen\fP, const struct http_cookie *\fIc\fP, struct http_response *\fIr\fP, void *\fIuser\fP);
     const char *\fItmpdir\fP;
     void *\fIuser\fP;
+    size_t \fImax_headers\fP;
 };
 .EE
 .in
@@ -195,6 +196,15 @@ other function pointers defined by
 .I user
 can be a null pointer.
 
+.I max_headers
+refers to the maximum number of header fields that shall be passed to the
+.IR "struct http_payload"
+object passed to the function pointed to by
+.IR payload .
+Any extra headers sent by the client outside this maximum value shall be
+silently ignored by
+.IR libweb .
+
 .SS HTTP payload
 
 When a client submits a request to the server,
@@ -224,6 +234,8 @@ struct http_payload
 
     const struct http_arg *\fIargs\fP;
     size_t \fIn_args\fP;
+    const struct http_header *\fIheaders\fP;
+    size_t \fIn_headers\fP;
 };
 .EE
 .in
@@ -260,6 +272,11 @@ defines a list of key-value pairs containing URL parameters. Its length
 is defined by
 .IR n_args .
 
+.I headers
+defines a list of key-value pairs containing header fields. Its length
+is defined by
+.IR n_headers .
+
 .SS HTTP POST payload
 
 As opposed to payload-less HTTP/1.1 operations, such as