Commit 1339bb53 authored by Yann Ylavic's avatar Yann Ylavic
Browse files

Merge r1808746, r1809028 from trunk: 

mod_rewrite/core: avoid the 'Vary: Host' header

In PR 58231 is was brought up that httpd adds the
Vary: Host header whenever a condition is set to true
in mod_rewrite or in an <If> block.

The https://tools.ietf.org/html/rfc7231#section-7.1.4
section seems to disallow this use case:

"The "Vary" header field in a response describes "
"what parts of a request message, "
"aside from the method, Host header field, [...]"

I had a chat with the folks in #traffic-server and
they don't see much point in having a Vary: Host header,
plus it was reported that Varnish doesn't like it very
much (namely it does not cache the response when
it sees the header, links of the report in the PR).

I don't see much value in this behavior of httpd so
I am inclined to remove this response header value,
but I'd be glad to get a more experienced opinion.



mod_rewrite,core: avoid Vary:Host (part 2)

This is a follow up of r1808746 after a chat
with Yann on dev@:

- the HTTP:Host variable suffers from the same problem
- the strcasecmp should be used to allow case-sensitive
  comparisons.
- in mod_rewrite is less cumbersome and more clean to just
  make the Host header check in lookup_header, so it will
  be automatically picked up by every part of the code
  that uses it. It shouldn't be a relevant overhead for
  mod_rewrite.


Submitted by: elukey
Reviewed by: elukey, ylavic, wrowe


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1812083 13f79535-47bb-0310-9956-ffa450edef68
parent 9889a8bf

CHANGES

+3 −0
Original line number Diff line number Diff line 
                                                         -*- coding: utf-8 -*-

Changes with Apache 2.4.29



  *) mod_rewrite, core: Avoid the 'Vary: Host' response header when HTTP_HOST

     is used in a condition that evaluates to true. PR 58231 [Luca Toscano]



  *) mod_http2: v0.10.12, removed optimization for mutex handling in bucket

     beams that could lead to assertion failure in edge cases.

     [Stefan Eissing]

STATUS

+0 −7
Original line number Diff line number Diff line
@@ -128,13 +128,6 @@ RELEASE SHOWSTOPPERS: 
PATCHES ACCEPTED TO BACKPORT FROM TRUNK:

  [ start all new proposals below, under PATCHES PROPOSED. ]



   *) mod_rewrite,core: Avoid the 'Vary: Host' response header when HTTP_HOST

                        is used in a condition that evaluates to true.

      trunk patch: http://svn.apache.org/r1808746

                   http://svn.apache.org/r1809028

      2.4.x patch: svn merge -c 1808746,1809028 ^/httpd/httpd/trunk .

      +1: elukey, ylavic, wrowe





PATCHES PROPOSED TO BACKPORT FROM TRUNK:

  [ New proposals should be added at the end of the list ]

modules/mappers/mod_rewrite.c

+4 −1
Original line number Diff line number Diff line
@@ -1802,7 +1802,10 @@ static const char *lookup_header(const char *name, rewrite_ctx *ctx) 
{

    const char *val = apr_table_get(ctx->r->headers_in, name);



    if (val) {

    /* Skip the 'Vary: Host' header combination

     * as indicated in rfc7231 section-7.1.4

     */

    if (val && strcasecmp(name, "Host") != 0) {

        ctx->vary_this = ctx->vary_this

                         ? apr_pstrcat(ctx->r->pool, ctx->vary_this, ", ",

                                       name, NULL)

server/util_expr_eval.c

+12 −2
Original line number Diff line number Diff line
@@ -1001,8 +1001,13 @@ static const char *req_table_func(ap_expr_eval_ctx_t *ctx, const void *data, 
        t = ctx->r->headers_in;

    else {                          /* req, http */

        t = ctx->r->headers_in;

        /* Skip the 'Vary: Host' header combination

         * as indicated in rfc7231 section-7.1.4

         */

        if (strcasecmp(arg, "Host")){

            add_vary(ctx, arg);

        }

    }

    return apr_table_get(t, arg);

}
@@ -1467,7 +1472,12 @@ static const char *req_header_var_fn(ap_expr_eval_ctx_t *ctx, const void *data) 
        return "";



    name = req_header_header_names[index];

    /* Skip the 'Vary: Host' header combination

     * as indicated in rfc7231 section-7.1.4

     */

    if (strcasecmp(name, "Host")){

        add_vary(ctx, name);

    }

    return apr_table_get(ctx->r->headers_in, name);

}