From 122541c06aa450e6b5c8b5c4724f342179fd0990 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Wed, 7 Sep 2011 21:24:49 +0200
Subject: [PATCH] [BUG] peers: don't keep a peers section which has a NULL
 frontend

If a peers section has no peer named as the local peer, we must destroy
it, otherwise a NULL peer frontend remains in the lists and a segfault
can happen upon a soft restart.

We also now report the missing peer name in order to help troubleshooting.
---
 src/cfgparse.c | 41 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/src/cfgparse.c b/src/cfgparse.c
index f63c61541..39a289af3 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -5870,8 +5870,8 @@ int check_config_validity()
 				cfgerr++;
 			}
 			else if (!curpeers->peers_fe) {
-				Alert("Proxy '%s': unable to identify local peer in peers section '%s'.\n",
-				      curproxy->id, curpeers->id);
+				Alert("Proxy '%s': unable to find local peer '%s' in peers section '%s'.\n",
+				      curproxy->id, localpeer, curpeers->id);
 				cfgerr++;
 			}
 		}
@@ -6553,6 +6553,43 @@ out_uri_auth_compat:
 				global.last_checks |= cfg_opts2[optnum].checks;
 	}
 
+	if (peers) {
+		struct peers *curpeers = peers, **last;
+		struct peer *p, *pb;
+
+		/* Remove all peers sections which don't have a valid listener.
+		 * This can happen when a peers section is never referenced and
+		 * does not contain a local peer.
+		 */
+		last = &peers;
+		while (*last) {
+			curpeers = *last;
+			if (curpeers->peers_fe) {
+				last = &curpeers->next;
+				continue;
+			}
+
+			Warning("Removing incomplete section 'peers %s' (no peer named '%s').\n",
+				curpeers->id, localpeer);
+
+			p = curpeers->remote;
+			while (p) {
+				pb = p->next;
+				free(p->id);
+				free(p);
+				p = pb;
+			}
+
+			/* Destroy and unlink this curpeers section.
+			 * Note: curpeers is backed up into *last.
+			 */
+			free(curpeers->id);
+			curpeers = curpeers->next;
+			free(*last);
+			*last = curpeers;
+		}
+	}
+
 	if (cfgerr > 0)
 		err_code |= ERR_ALERT | ERR_FATAL;
  out: