From: Willy Tarreau <w@1wt.eu>
Date: Mon, 14 Jan 2019 16:07:39 +0000 (+0100)
Subject: BUG/MINOR: backend: BE_LB_LKUP_CHTREE is a value, not a bit
X-Git-Tag: v2.0-dev1~211
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6c30be52da3d949a8dd6fb5e2de7319c031e656e;p=thirdparty%2Fhaproxy.git

BUG/MINOR: backend: BE_LB_LKUP_CHTREE is a value, not a bit

There are a few instances where the lookup algo is tested against
BE_LB_LKUP_CHTREE using a binary "AND" operation while this macro
is a value among a set, and not a bit. The test happens to work
because the value is exactly 4 and no bit overlaps with the other
possible values but this is a latent bug waiting for a new LB algo
to appear to strike. At the moment the only other algo sharing a bit
with it is the "first" algo which is never supported in the same code
places.

This fix should be backported to maintained versions for safety if it
passes easily, otherwise it's not important as it will not fix any
visible issue.
---

diff --git a/src/backend.c b/src/backend.c
index 00537f094b..13543c90e4 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -185,7 +185,7 @@ static struct server *get_server_sh(struct proxy *px, const char *addr, int len,
 	if ((px->lbprm.algo & BE_LB_HASH_MOD) == BE_LB_HMOD_AVAL)
 		h = full_hash(h);
  hash_done:
-	if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
+	if ((px->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 		return chash_get_server_hash(px, h, avoid);
 	else
 		return map_get_server_hash(px, h);
@@ -238,7 +238,7 @@ static struct server *get_server_uh(struct proxy *px, char *uri, int uri_len, co
 	if ((px->lbprm.algo & BE_LB_HASH_MOD) == BE_LB_HMOD_AVAL)
 		hash = full_hash(hash);
  hash_done:
-	if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
+	if ((px->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 		return chash_get_server_hash(px, hash, avoid);
 	else
 		return map_get_server_hash(px, hash);
@@ -295,7 +295,7 @@ static struct server *get_server_ph(struct proxy *px, const char *uri, int uri_l
 				if ((px->lbprm.algo & BE_LB_HASH_MOD) == BE_LB_HMOD_AVAL)
 					hash = full_hash(hash);
 
-				if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
+				if ((px->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 					return chash_get_server_hash(px, hash, avoid);
 				else
 					return map_get_server_hash(px, hash);
@@ -369,7 +369,7 @@ static struct server *get_server_ph_post(struct stream *s, const struct server *
 				if ((px->lbprm.algo & BE_LB_HASH_MOD) == BE_LB_HMOD_AVAL)
 					hash = full_hash(hash);
 
-				if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
+				if ((px->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 					return chash_get_server_hash(px, hash, avoid);
 				else
 					return map_get_server_hash(px, hash);
@@ -465,7 +465,7 @@ static struct server *get_server_hh(struct stream *s, const struct server *avoid
 	if ((px->lbprm.algo & BE_LB_HASH_MOD) == BE_LB_HMOD_AVAL)
 		hash = full_hash(hash);
  hash_done:
-	if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
+	if ((px->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 		return chash_get_server_hash(px, hash, avoid);
 	else
 		return map_get_server_hash(px, hash);
@@ -510,7 +510,7 @@ static struct server *get_server_rch(struct stream *s, const struct server *avoi
 	if ((px->lbprm.algo & BE_LB_HASH_MOD) == BE_LB_HMOD_AVAL)
 		hash = full_hash(hash);
  hash_done:
-	if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
+	if ((px->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 		return chash_get_server_hash(px, hash, avoid);
 	else
 		return map_get_server_hash(px, hash);
@@ -640,7 +640,7 @@ int assign_server(struct stream *s)
 			if ((s->be->lbprm.algo & BE_LB_KIND) == BE_LB_KIND_RR) {
 				if ((s->be->lbprm.algo & BE_LB_PARM) == BE_LB_RR_RANDOM)
 					srv = get_server_rnd(s, prev_srv);
-				else if (s->be->lbprm.algo & BE_LB_LKUP_CHTREE)
+				else if ((s->be->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 					srv = chash_get_next_server(s->be, prev_srv);
 				else
 					srv = map_get_server_rr(s->be, prev_srv);
@@ -716,7 +716,7 @@ int assign_server(struct stream *s)
 			 * back to round robin on the map.
 			 */
 			if (!srv) {
-				if (s->be->lbprm.algo & BE_LB_LKUP_CHTREE)
+				if ((s->be->lbprm.algo & BE_LB_LKUP) == BE_LB_LKUP_CHTREE)
 					srv = chash_get_next_server(s->be, prev_srv);
 				else
 					srv = map_get_server_rr(s->be, prev_srv);