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

svn:r361

diff --git a/evdns.c b/evdns.c
index e68ab8456fdb6fcecd6ba0c1493ec5d57d4caddb..63dd12656d00fef82833c4fd86fad421bbf40fef 100644 (file)
--- 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;
 }