Implement user quota

This feature allows admins to set a specific quota for each user, in
MiB. This feature is particularly useful for shared instances, where
unlimited user storage might be unfeasible or even dangerous for the
server.

Also, a nice HTML5 <progress> element has been added to the site that
shows how much of the quota has been consumed.

If no quota is set, slcl falls back to the default behaviour i.e.,
assume unlimited storage.

Limitations:

- While HTTP does specify a Content-Length, which determines the length
of the whole request, it does not specify how many files are involved
or their individual sizes.
- Because of this, if multiple files are uploaded simultaneously, the
whole request would be dropped if user quota is exceeded, even if not
all files exceeded it.
- Also, Content-Length adds the length of some HTTP boilerplate
(e.g.: boundaries), but slcl must rely on this before accepting the
whole request. In other words, this means some requests might be
rejected by slcl because of the extra bytes caused by such boilerplate.
- When the quota is exceeded, slcl must close the connection so that
the rest of the transfer is cancelled. Unfortunately, this means no
HTML can be sent back to the customer to inform about the situation.

1 files changed, 6 insertions, 1 deletions

diff --git a/usergen b/usergen
index 875ef20..ec63fd3 100755
--- a/usergen
+++ b/usergen
@@ -1,9 +1,13 @@
 #! /bin/sh
 
+set -e
+
 echo Username: >&2
 read -r USER
 echo Password: >&2
 read -r PWD
+echo "Quota, in MiB (leave empty for unlimited quota):" >&2
+read -r QUOTA
 
 PWD=$(printf '%s' $PWD | xxd -p | tr -d '\n')
 SALT=$(openssl rand 32 | xxd -p | tr -d '\n')
@@ -24,6 +28,7 @@ cat <<-EOF
     "name": "$USER",
     "password": "$PWD",
     "salt": "$SALT",
-    "key": "$KEY"
+    "key": "$KEY",
+    "quota": "$QUOTA"
 }
 EOF