tree 7208e938e7023ab9bf98ef4edb0d940c3f213a2c
parent 4be9803914ae7156109c915659aad216e4a3c6c1
author Christopher Faulet <cfaulet@haproxy.com> 1500370928 +0200
committer Willy Tarreau <w@1wt.eu> 1500384146 +0200
encoding latin1

BUG/MEDIUM: http: Switch HTTP responses in TUNNEL mode when body length is undefined

When the body length of a HTTP response is undefined, the HTTP parser is blocked
in the body parsing. Before HAProxy 1.7, in this case, because
AN_RES_HTTP_XFER_BODY is never set, there is no visible effect. When the server
closes its connection to terminate the response, HAProxy catches it as a normal
closure. Since 1.7, we always set this analyzer to enter at least once in
http_response_forward_body. But, in the present case, when the server connection
is closed, http_response_forward_body is called one time too many. The response
is correctly sent to the client, but an error is catched and logged with "SD--"
flags.

To reproduce the bug, you can use the configuration "tests/test-fsm.cfg". The
tests 3 and 21 hit the bug.

Idea to fix the bug is to switch the response in TUNNEL mode without switching
the request. This is possible because of previous patches.

First, we need to detect responses with undefined body length during states
synchronization. Excluding tunnelled transactions, when the response length is
undefined, TX_CON_WANT_CLO is always set on the transaction. So, when states are
synchronized, if TX_CON_WANT_CLO is set, the response is switched in TUNNEL mode
and the request remains unchanged.

Then, in http_msg_forward_body, we add a specific check to switch the response
in DONE mode if the body length is undefined and if there is no data filter.

This patch depends on following previous commits:

  * MINOR: http: Switch requests/responses in TUNNEL mode only by checking txn flags
  * MINOR: http: Reorder/rewrite checks in http_resync_states

This patch must be backported in 1.7 with 2 previous ones.