[MEDIUM] add support for "balance hdr(name)"
There is a patch made by me that allow for balancing on any http header
field.
[WT:
made minor changes:
- turned 'balance header name' into 'balance hdr(name)' to match more
closely the ACL syntax for easier future convergence
- renamed the proxy structure fields header_* => hh_*
- made it possible to use the domain name reduction to any header, not
only "host" since it makes sense to do it with other ones.
Otherwise patch looks good.
/WT]
diff --git a/src/backend.c b/src/backend.c
index 6ca5059..321c8a8 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -1279,6 +1279,80 @@
/*
+ * This function tries to find a running server for the proxy <px> following
+ * the Header parameter hash method. It looks for a specific parameter in the
+ * URL and hashes it to compute the server ID. This is useful to optimize
+ * performance by avoiding bounces between servers in contexts where sessions
+ * are shared but cookies are not usable. If the parameter is not found, NULL
+ * is returned. If any server is found, it will be returned. If no valid server
+ * is found, NULL is returned.
+ */
+struct server *get_server_hh(struct session *s)
+{
+ unsigned long hash = 0;
+ struct http_txn *txn = &s->txn;
+ struct http_msg *msg = &txn->req;
+ struct proxy *px = s->be;
+ unsigned int plen = px->hh_len;
+ unsigned long len;
+ struct hdr_ctx ctx;
+ const char *p;
+
+ /* tot_weight appears to mean srv_count */
+ if (px->lbprm.tot_weight == 0)
+ return NULL;
+
+ if (px->lbprm.map.state & PR_MAP_RECALC)
+ recalc_server_map(px);
+
+ ctx.idx = 0;
+
+ /* if the message is chunked, we skip the chunk size, but use the value as len */
+ http_find_header2(px->hh_name, plen, msg->sol, &txn->hdr_idx, &ctx);
+
+ /* if the header is not found or empty, let's fallback to round robin */
+ if (!ctx.idx || !ctx.vlen)
+ return NULL;
+
+ /* Found a the hh_name in the headers.
+ * we will compute the hash based on this value ctx.val.
+ */
+ len = ctx.vlen;
+ p = (char *)ctx.line + ctx.val;
+ if (!px->hh_match_domain) {
+ while (len) {
+ hash = *p + (hash << 6) + (hash << 16) - hash;
+ len--;
+ p++;
+ }
+ } else {
+ int dohash = 0;
+ p += len - 1;
+ /* special computation, use only main domain name, not tld/host
+ * going back from the end of string, start hashing at first
+ * dot stop at next.
+ * This is designed to work with the 'Host' header, and requires
+ * a special option to activate this.
+ */
+ while (len) {
+ if (*p == '.') {
+ if (!dohash)
+ dohash = 1;
+ else
+ break;
+ } else {
+ if (dohash)
+ hash = *p + (hash << 6) + (hash << 16) - hash;
+ }
+ len--;
+ p--;
+ }
+ }
+ return px->lbprm.map.srv[hash % px->lbprm.tot_weight];
+}
+
+
+/*
* This function applies the load-balancing algorithm to the session, as
* defined by the backend it is assigned to. The session is then marked as
* 'assigned'.
@@ -1396,6 +1470,19 @@
}
}
break;
+ case BE_LB_ALGO_HH:
+ /* Header Parameter hashing */
+ s->srv = get_server_hh(s);
+
+ if (!s->srv) {
+ /* parameter not found, fall back to round robin on the map */
+ s->srv = get_server_rr_with_conns(s->be, s->prev_srv);
+ if (!s->srv) {
+ err = SRV_STATUS_FULL;
+ goto out;
+ }
+ }
+ break;
default:
/* unknown balancing algorithm */
err = SRV_STATUS_INTERNAL;
@@ -2022,9 +2109,37 @@
else if ( curproxy->url_param_post_limit < 3 )
curproxy->url_param_post_limit = 3; /* minimum example: S=3 or \r\nS=6& */
}
+ }
+ else if (!strncmp(args[0], "hdr(", 4)) {
+ const char *beg, *end;
+
+ beg = args[0] + 4;
+ end = strchr(beg, ')');
+
+ if (!end || end == beg) {
+ snprintf(err, errlen, "'balance hdr(name)' requires an http header field name.");
+ return -1;
+ }
+
+ curproxy->lbprm.algo &= ~BE_LB_ALGO;
+ curproxy->lbprm.algo |= BE_LB_ALGO_HH;
+
+ free(curproxy->hh_name);
+ curproxy->hh_len = end - beg;
+ curproxy->hh_name = my_strndup(beg, end - beg);
+ curproxy->hh_match_domain = 0;
+
+ if (*args[1]) {
+ if (strcmp(args[1], "use_domain_only")) {
+ snprintf(err, errlen, "'balance hdr(name)' only accepts 'use_domain_only' modifier.");
+ return -1;
+ }
+ curproxy->hh_match_domain = 1;
+ }
+
}
else {
- snprintf(err, errlen, "'balance' only supports 'roundrobin', 'leastconn', 'source', 'uri' and 'url_param' options.");
+ snprintf(err, errlen, "'balance' only supports 'roundrobin', 'leastconn', 'source', 'uri', 'url_param' and 'hdr(name)' options.");
return -1;
}
return 0;