tree 9d08ed594990e8424b28cc1d2ebc5155400e2a75
parent 27cd2233a3ba47c012430effbff5470b1545d444
author Willy Tarreau <w@1wt.eu> 1546547239 +0100
committer Willy Tarreau <w@1wt.eu> 1546550865 +0100
encoding latin1

BUG/MEDIUM: mux-h1: don't enforce chunked encoding on requests

Recent commit 4710d20 ("BUG/MEDIUM: mux-h1: make HTX chunking
consistent with H2") tried to address chunking inconsistencies between
H1/HTX/H2 and has enforced it on every outgoing message carrying
H1_MF_XFER_LEN without H1_MF_CLEN nor H1_MF_CHNK. But it also does it
on requests, which is not appropriate since a request by default
doesn't have a message body unless explicitly mentioned. Also make
sure we only do this on HTTP/1.1 messages.

The problem is to guarantee the highest level of compatibility between
H1/H1, H1/H2, H2/H1 in each direction regarding the lack of content-
length. We have this truth table (a star '*' indicates which one can
pass trailers) :

  H1 client -> H1 server :
     request:
        CL=0 TE=0 XL=1 -> CL=0 TE=0
        CL=0 TE=1 XL=1 -> CL=0 TE=1 *
        CL=1 TE=0 XL=1 -> CL=1 TE=0
        CL=1 TE=1 XL=1 -> CL=1 TE=1 *

     response:
        CL=0 TE=0 XL=0 -> CL=0 TE=0
        CL=0 TE=1 XL=1 -> CL=0 TE=1 *
        CL=1 TE=0 XL=1 -> CL=1 TE=0
        CL=1 TE=1 XL=1 -> CL=1 TE=1 *

  H2 client -> H1 server : (H2 messages always carry XFER_LEN)
     request:
        CL=0 XL=1 -> CL=0 TE=0
        CL=1 XL=1 -> CL=1 TE=0

     response:
        CL=0 TE=0 XL=0 -> CL=0
        CL=0 TE=1 XL=1 -> CL=0 *
        CL=1 TE=0 XL=1 -> CL=1
        CL=1 TE=1 XL=1 -> CL=1 *

  H1 client -> H2 server : (H2 messages always carry XFER_LEN)
     request:
        CL=0 TE=0 XL=1 -> CL=0
        CL=0 TE=1 XL=1 -> CL=0 *
        CL=1 TE=0 XL=1 -> CL=1
        CL=1 TE=1 XL=1 -> CL=1 *

     response:
        CL=0 XL=1 -> CL=0 TE=1 *
        CL=1 XL=1 -> CL=1 TE=0

For H1 client to H2 server, it will be possible to rely on the presence
of "TE: trailers"  in the H1 request to automatically switch to chunks
in the response, and be able to pass trailers at the end. For now this
check is not implemented so an H2 response missing a content-length to
an H1 request will always have a transfer-encoding header added and
trailers will be forwarded if any.

This patch depends on previous commit "MINOR: mux-h1: parse the
content-length header on output and set H1_MF_CLEN" to work properly.

Since the aforementioned commit is scheduled for backport to 1.9 this
commit must also be backported to 1.9.