---------------------
PatchSet 12261 
Date: 2008/06/27 20:55:52
Author: hno
Branch: SQUID_2_7
Tag: (none) 
Log:
Bug #2393: DNS requests retried indefinitely at full speed on failed TCP connection

Make the retransmit queue deal with TCP errors instead of immediately
retransmit the query on a failed TCP connection to the DNS server.

TCP is needed on large DNS responses, not fitting within the quite small
DNS over UDP maximum packet size.

Members: 
	src/dns_internal.c:1.63.2.5->1.63.2.6 

Index: squid/src/dns_internal.c
===================================================================
RCS file: /cvsroot/squid/squid/src/dns_internal.c,v
retrieving revision 1.63.2.5
retrieving revision 1.63.2.6
diff -u -r1.63.2.5 -r1.63.2.6
--- squid/src/dns_internal.c	4 May 2008 23:26:36 -0000	1.63.2.5
+++ squid/src/dns_internal.c	27 Jun 2008 20:55:52 -0000	1.63.2.6
@@ -1,6 +1,6 @@
 
 /*
- * $Id: dns_internal.c,v 1.63.2.5 2008/05/04 23:26:36 hno Exp $
+ * $Id: dns_internal.c,v 1.63.2.6 2008/06/27 20:55:52 hno Exp $
  *
  * DEBUG: section 78    DNS lookups; interacts with lib/rfc1035.c
  * AUTHOR: Duane Wessels
@@ -704,9 +704,8 @@
 	return;
     }
     if (n <= 0) {
-	debug(78, 2) ("idnsReadTcp: Short response for %s.\n", q->name);
-	dlinkDelete(&q->lru, &lru_list);
-	idnsSendQuery(q);
+	debug(78, 1) ("idnsReadTcp: Short response from nameserver %d for %s.\n", ns + 1, q->name);
+	idnsTcpCleanup(q);
 	return;
     }
     fd_bytes(fd, n, FD_READ);
@@ -733,8 +732,7 @@
     if (errflag == COMM_ERR_CLOSING)
 	return;
     if (errflag) {
-	dlinkDelete(&q->lru, &lru_list);
-	idnsSendQuery(q);
+	idnsTcpCleanup(q);
 	return;
     }
     commSetSelect(q->tcp_socket, COMM_SELECT_READ, idnsReadTcp, q, 0);
@@ -747,8 +745,9 @@
     idns_query *q = data;
     short nsz;
     if (status != COMM_OK) {
-	dlinkDelete(&q->lru, &lru_list);
-	idnsSendQuery(q);
+	int ns = (q->nsends - 1) % nns;
+	debug(78, 1) ("idnsSendTcpQuery: Failed to connect to DNS server %d using TCP\n", ns + 1);
+	idnsTcpCleanup(q);
 	return;
     }
     memBufInit(&buf, q->sz + 2, q->sz + 2);
@@ -837,7 +836,6 @@
 	    return;
 	}
 	if (q->rcode == 3 && q->do_searchpath && q->attempt < MAX_ATTEMPT) {
-	    assert(NULL == message->answer);
 	    strcpy(q->name, q->orig);
 	    if (q->domain < npc) {
 		strcat(q->name, ".");