From 28246587c0520a9e812fc6ed64b3d7c173864789 Mon Sep 17 00:00:00 2001
From: Niels Provos <provos@gmail.com>
Date: Mon, 28 May 2007 21:17:35 +0000
Subject: [PATCH] treat SERVERFAILED as a timeout; from tor cvs via Nick
 Mathewson

svn:r359
---
 evdns.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/evdns.c b/evdns.c
index f66239bb..82b45a7f 100644
--- a/evdns.c
+++ b/evdns.c
@@ -698,7 +698,6 @@ reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply)
 		}
 
 		switch(error) {
-		case DNS_ERR_SERVERFAILED:
 		case DNS_ERR_NOTIMPL:
 		case DNS_ERR_REFUSED:
 			// we regard these errors as marking a bad nameserver
@@ -710,6 +709,14 @@ reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply)
 				if (!request_reissue(req)) return;
 			}
 			break;
+		case DNS_ERR_SERVERFAILED:
+			// rcode 2 (servfailed) sometimes means "we are broken" and
+			// sometimes (with some binds) means "that request was very
+			// confusing."  Treat this as a timeout, not a failure.
+			log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver %s; "
+				"will allow the request to time out.",
+				debug_ntoa(req->ns->address));
+			break;
 		default:
 			// we got a good reply from the nameserver
 			nameserver_up(req->ns);