From: Niels Provos <provos@gmail.com>
Date: Mon, 28 May 2007 21:20:57 +0000 (+0000)
Subject: fail quicker on bad replies; from tor cvs via Nick Mathewson
X-Git-Tag: release-2.0.1-alpha~620
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=5d3b6a83870d68c0ec4ed4fc60a6710d8ad938df;p=libevent

fail quicker on bad replies; from tor cvs via Nick Mathewson


svn:r361
---

diff --git a/evdns.c b/evdns.c
index e68ab845..63dd1265 100644
--- a/evdns.c
+++ b/evdns.c
@@ -808,10 +808,11 @@ reply_parse(u8 *packet, int length) {
 	u32 _t32;  // used by the macros
 	char tmp_name[256]; // used by the macros
 
-	u16 trans_id, flags, questions, answers, authority, additional, datalength;
+	u16 trans_id, questions, answers, authority, additional, datalength;
+        u16 flags = 0;
 	u32 ttl, ttl_r = 0xffffffff;
 	struct reply reply;
-	struct request *req;
+	struct request *req = NULL;
 	unsigned int i;
 
 	GET16(trans_id);
@@ -825,15 +826,14 @@ reply_parse(u8 *packet, int length) {
 
 	req = request_find_from_trans_id(trans_id);
 	if (!req) return -1;
-	// XXXX should the other return points also call reply_handle? -NM
 
 	memset(&reply, 0, sizeof(reply));
 
+	// If it's not an answer, it doesn't correspond to any request.
 	if (!(flags & 0x8000)) return -1;  // must be an answer
 	if (flags & 0x020f) {
 		// there was an error
-		reply_handle(req, flags, 0, NULL);
-		return -1;
+		goto err;
 	}
 	// if (!answers) return;  // must have an answer of some form
 
@@ -852,7 +852,7 @@ reply_parse(u8 *packet, int length) {
 		//   <label:name><u16:type><u16:class>
 		SKIP_NAME;
 		j += 4;
-		if (j >= length) return -1;
+		if (j >= length) goto err;
 	}
 
 	// now we have the answer section which looks like
@@ -873,13 +873,13 @@ reply_parse(u8 *packet, int length) {
 				j += datalength; continue;
 			}
 			if ((datalength & 3) != 0) /* not an even number of As. */
-				return -1;
+			    goto err;
 			addrcount = datalength >> 2;
 			addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
 
 			ttl_r = MIN(ttl_r, ttl);
 			// we only bother with the first four addresses.
-			if (j + 4*addrtocopy > length) return -1;
+			if (j + 4*addrtocopy > length) goto err;
 			memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
 				   packet + j, 4*addrtocopy);
 			j += 4*addrtocopy;
@@ -892,7 +892,7 @@ reply_parse(u8 *packet, int length) {
 			}
 			if (name_parse(packet, length, &j, reply.data.ptr.name,
 						   sizeof(reply.data.ptr.name))<0)
-				return -1;
+				goto err;
 			ttl_r = MIN(ttl_r, ttl);
 			reply.have_answer = 1;
 			break;
@@ -902,13 +902,13 @@ reply_parse(u8 *packet, int length) {
 				j += datalength; continue;
 			}
 			if ((datalength & 15) != 0) /* not an even number of AAAAs. */
-				return -1;
+				goto err;
 			addrcount = datalength >> 4;  // each address is 16 bytes long
 			addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
 			ttl_r = MIN(ttl_r, ttl);
 
 			// we only bother with the first four addresses.
-			if (j + 16*addrtocopy > length) return -1;
+			if (j + 16*addrtocopy > length) goto err;
 			memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
 				   packet + j, 16*addrtocopy);
 			reply.data.aaaa.addrcount += addrtocopy;
@@ -924,6 +924,8 @@ reply_parse(u8 *packet, int length) {
 	reply_handle(req, flags, ttl_r, &reply);
 	return 0;
  err:
+	if (req)
+		reply_handle(req, flags, 0, NULL);
 	return -1;
 }