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MEDIUM: compression: consider the "q=" attribute in Accept-Encoding

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Till now we didn't consider "q=". It's problematic because the first
effect is that compression tokens were not even matched if it was
present.

It is important to parse it correctly because we still want to allow
a user-agent to send "q=0" to explicitly disable a compressor, or to
specify its preferences.

Now, q-values are respected in order of precedence, and when several
q-values are equal, the first occurrence is used.
This commit is contained in:
Willy Tarreau 2014-03-19 12:07:52 +01:00
parent f21be328e8
commit 0e9b1b4d1f
1 changed files with 90 additions and 13 deletions
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103
src/proto_http.c
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@ -2144,6 +2144,38 @@ static inline int http_skip_chunk_crlf(struct http_msg *msg)
return 1;
}
/* Parses a qvalue and returns it multipled by 1000, from 0 to 1000. If the
* value is larger than 1000, it is bound to 1000. The parser consumes up to
* 1 digit, one dot and 3 digits and stops on the first invalid character.
* Unparsable qvalues return 1000 as "q=1.000".
*/
int parse_qvalue(const char *qvalue)
{
int q = 1000;
if (!isdigit(*qvalue))
goto out;
q = (*qvalue++ - '0') * 1000;
if (*qvalue++ != '.')
goto out;
if (!isdigit(*qvalue))
goto out;
q += (*qvalue++ - '0') * 100;
if (!isdigit(*qvalue))
goto out;
q += (*qvalue++ - '0') * 10;
if (!isdigit(*qvalue))
goto out;
q += (*qvalue++ - '0') * 1;
out:
if (q > 1000)
q = 1000;
return q;
}
/*
* Selects a compression algorithm depending on the client request.
@ -2175,28 +2207,73 @@ int select_compression_request_header(struct session *s, struct buffer *req)
/* 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))) {
int best_q = 0;
ctx.idx = 0;
while (http_find_header2("Accept-Encoding", 15, req->p, &txn->hdr_idx, &ctx)) {
const char *qval;
int q;
int toklen;
/* try to isolate the token from the optional q-value */
toklen = 0;
while (toklen < ctx.vlen && http_is_token[(unsigned char)*(ctx.line + ctx.val + toklen)])
toklen++;
qval = ctx.line + ctx.val + toklen;
while (1) {
while (qval < ctx.line + ctx.val + ctx.vlen && http_is_lws[(unsigned char)*qval])
qval++;
if (qval >= ctx.line + ctx.val + ctx.vlen || *qval != ';') {
qval = NULL;
break;
}
qval++;
while (qval < ctx.line + ctx.val + ctx.vlen && http_is_lws[(unsigned char)*qval])
qval++;
if (qval >= ctx.line + ctx.val + ctx.vlen) {
qval = NULL;
break;
}
if (strncmp(qval, "q=", MIN(ctx.line + ctx.val + ctx.vlen - qval, 2)) == 0)
break;
while (qval < ctx.line + ctx.val + ctx.vlen && *qval != ';')
qval++;
}
/* here we have qval pointing to the first "q=" attribute or NULL if not found */
q = qval ? parse_qvalue(qval + 2) : 1000;
if (q <= best_q)
continue;
for (comp_algo = comp_algo_back; comp_algo; comp_algo = comp_algo->next) {
if (word_match(ctx.line + ctx.val, ctx.vlen, comp_algo->name, comp_algo->name_len)) {
if (*(ctx.line + ctx.val) == '*' ||
word_match(ctx.line + ctx.val, toklen, comp_algo->name, comp_algo->name_len)) {
s->comp_algo = comp_algo;
/* remove all occurrences of the header when "compression offload" is set */
if ((s->be->comp && s->be->comp->offload) ||
(s->fe->comp && s->fe->comp->offload)) {
http_remove_header2(msg, &txn->hdr_idx, &ctx);
ctx.idx = 0;
while (http_find_header2("Accept-Encoding", 15, req->p, &txn->hdr_idx, &ctx)) {
http_remove_header2(msg, &txn->hdr_idx, &ctx);
}
}
return 1;
best_q = q;
break;
}
}
}
}
/* remove all occurrences of the header when "compression offload" is set */
if (s->comp_algo) {
if ((s->be->comp && s->be->comp->offload) || (s->fe->comp && s->fe->comp->offload)) {
http_remove_header2(msg, &txn->hdr_idx, &ctx);
ctx.idx = 0;
while (http_find_header2("Accept-Encoding", 15, req->p, &txn->hdr_idx, &ctx)) {
http_remove_header2(msg, &txn->hdr_idx, &ctx);
}
}
return 1;
}
/* identity is implicit does not require headers */
if ((s->be->comp && (comp_algo_back = s->be->comp->algos)) || (s->fe->comp && (comp_algo_back = s->fe->comp->algos))) {
for (comp_algo = comp_algo_back; comp_algo; comp_algo = comp_algo->next) {