tree 5c3101d04c81e788ca5a2c85ef80766ff761cbfb
parent 3ad7b3db5c8d5e977f1f62fd82be784bc07b63ab
author Christopher Faulet <cfaulet@haproxy.com> 1611572520 +0100
committer Christopher Faulet <cfaulet@haproxy.com> 1612191183 +0100

BUG/MEDIUM: filters/htx: Fix data forwarding when payload length is unknown

It is only a problem on the response path because the request payload length
it always known. But when a filter is registered to analyze the response
payload, the filtering may hang if the server closes just after the headers.

The root cause of the bug comes from an attempt to allow the filters to not
immediately forward the headers if necessary. A filter may choose to hold
the headers by not forwarding any bytes of the payload. For a message with
no payload but a known payload length, there is always a EOM block to
forward. Thus holding the EOM block for bodyless messages is a good way to
also hold the headers. However, messages with an unknown payload length,
there is no EOM block finishing the message, but only a SHUTR flag on the
channel to mark the end of the stream. If there is no payload when it
happens, there is no payload at all to forward. In the filters API, it is
wrongly detected as a condition to not forward the headers.

Because it is not the most used feature and not the obvious one, this patch
introduces another way to hold the message headers at the begining of the
forwarding. A filter flag is added to explicitly says the headers should be
hold. A filter may choose to set the STRM_FLT_FL_HOLD_HTTP_HDRS flag and not
forwad anything to hold the headers. This flag is removed at each call, thus
it must always be explicitly set by filters. This flag is only evaluated if
no byte has ever been forwarded because the headers are forwarded with the
first byte of the payload.

reg-tests/filters/random-forwarding.vtc reg-test is updated to also test
responses with unknown payload length (with and without payload).

This patch must be backported as far as 2.0.

(cherry picked from commit 6071c2d12dd2ff1f5876a2ace313a81259f211cd)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 65e7b380ccc8a52829cbb216b27b8061c658ff88)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit ccd69b38a23f6bfeb981ce6469f986707f6833c5)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 6ae567f366d5b5775739331b457c29a38586dda1)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>