From: Willy Tarreau <w@1wt.eu>
Date: Sat, 5 Jan 2013 15:20:35 +0000 (+0100)
Subject: BUG/MINOR: http-compression: lookup Cache-Control in the response, not the request
X-Git-Tag: v1.5-dev18~134
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=56e9ffa6a6da0227776f278afb9f7dafa1963606;p=thirdparty%2Fhaproxy.git

BUG/MINOR: http-compression: lookup Cache-Control in the response, not the request

As stated in both RFC2616 and the http-bis drafts, Cache-Control:
no-transform must be looked up in the response since we're modifying
the response. However, its presence in the request is irrelevant to
any changes in the response :

  7.2.1.6. no-transform
   The "no-transform" request directive indicates that an intermediary
   (whether or not it implements a cache) MUST NOT change the Content-
   Encoding, Content-Range or Content-Type request header fields, nor
   the request representation.

  7.2.2.9. no-transform
   The "no-transform" response directive indicates that an intermediary
   (regardless of whether it implements a cache) MUST NOT change the
   Content-Encoding, Content-Range or Content-Type response header
   fields, nor the response representation.

Note: according to the specs, we're supposed to emit the following
response header :

  Warning: 214 transformation applied

However no other product seems to do it, so the effect on user agents
is unclear.
---

diff --git a/src/proto_http.c b/src/proto_http.c
index aaa94766e4..a2f14c9293 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -1994,15 +1994,6 @@ int select_compression_request_header(struct session *s, struct buffer *req)
 	    return 0;
 	}
 
-	ctx.idx = 0;
-	/* no compression when Cache-Control: no-transform found */
-	while (http_find_header2("Cache-Control", 13, req->p, &txn->hdr_idx, &ctx)) {
-		if (word_match(ctx.line + ctx.val, ctx.vlen, "no-transform", 12)) {
-			s->comp_algo = NULL;
-			return 0;
-		}
-	}
-
 	/* search for the algo in the backend in priority or the frontend */
 	if ((s->be->comp && (comp_algo_back = s->be->comp->algos)) || (s->fe->comp && (comp_algo_back = s->fe->comp->algos))) {
 		ctx.idx = 0;
@@ -2073,6 +2064,13 @@ int select_compression_response_header(struct session *s, struct buffer *res)
 	if (http_find_header2("Content-Encoding", 16, res->p, &txn->hdr_idx, &ctx))
 		goto fail;
 
+	/* no compression when Cache-Control: no-transform is present in the message */
+	ctx.idx = 0;
+	while (http_find_header2("Cache-Control", 13, res->p, &txn->hdr_idx, &ctx)) {
+		if (word_match(ctx.line + ctx.val, ctx.vlen, "no-transform", 12))
+			goto fail;
+	}
+
 	comp_type = NULL;
 
 	/* we don't want to compress multipart content-types, nor content-types that are