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

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svn:r361
This commit is contained in:
Niels Provos 2007-05-28 21:20:57 +00:00
parent d06ab8569e
commit 5d3b6a8387
1 changed files with 13 additions and 11 deletions
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24
evdns.c
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@ -808,10 +808,11 @@ reply_parse(u8 *packet, int length) {
u32 _t32; // used by the macros u32 _t32; // used by the macros
char tmp_name[256]; // 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; u32 ttl, ttl_r = 0xffffffff;
struct reply reply; struct reply reply;
struct request *req; struct request *req = NULL;
unsigned int i; unsigned int i;
GET16(trans_id); GET16(trans_id);
@ -825,15 +826,14 @@ reply_parse(u8 *packet, int length) {
req = request_find_from_trans_id(trans_id); req = request_find_from_trans_id(trans_id);
if (!req) return -1; if (!req) return -1;
// XXXX should the other return points also call reply_handle? -NM
memset(&reply, 0, sizeof(reply)); 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 & 0x8000)) return -1; // must be an answer
if (flags & 0x020f) { if (flags & 0x020f) {
// there was an error // there was an error
reply_handle(req, flags, 0, NULL); goto err;
return -1;
} }
// if (!answers) return; // must have an answer of some form // 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> // <label:name><u16:type><u16:class>
SKIP_NAME; SKIP_NAME;
j += 4; j += 4;
if (j >= length) return -1; if (j >= length) goto err;
} }
// now we have the answer section which looks like // now we have the answer section which looks like
@ -873,13 +873,13 @@ reply_parse(u8 *packet, int length) {
j += datalength; continue; j += datalength; continue;
} }
if ((datalength & 3) != 0) /* not an even number of As. */ if ((datalength & 3) != 0) /* not an even number of As. */
return -1; goto err;
addrcount = datalength >> 2; addrcount = datalength >> 2;
addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (unsigned)addrcount); addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
ttl_r = MIN(ttl_r, ttl); ttl_r = MIN(ttl_r, ttl);
// we only bother with the first four addresses. // 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], memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
packet + j, 4*addrtocopy); packet + j, 4*addrtocopy);
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, if (name_parse(packet, length, &j, reply.data.ptr.name,
sizeof(reply.data.ptr.name))<0) sizeof(reply.data.ptr.name))<0)
return -1; goto err;
ttl_r = MIN(ttl_r, ttl); ttl_r = MIN(ttl_r, ttl);
reply.have_answer = 1; reply.have_answer = 1;
break; break;
@ -902,13 +902,13 @@ reply_parse(u8 *packet, int length) {
j += datalength; continue; j += datalength; continue;
} }
if ((datalength & 15) != 0) /* not an even number of AAAAs. */ if ((datalength & 15) != 0) /* not an even number of AAAAs. */
return -1; goto err;
addrcount = datalength >> 4; // each address is 16 bytes long addrcount = datalength >> 4; // each address is 16 bytes long
addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount); addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
ttl_r = MIN(ttl_r, ttl); ttl_r = MIN(ttl_r, ttl);
// we only bother with the first four addresses. // 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], memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
packet + j, 16*addrtocopy); packet + j, 16*addrtocopy);
reply.data.aaaa.addrcount += addrtocopy; reply.data.aaaa.addrcount += addrtocopy;
@ -924,6 +924,8 @@ reply_parse(u8 *packet, int length) {
reply_handle(req, flags, ttl_r, &reply); reply_handle(req, flags, ttl_r, &reply);
return 0; return 0;
err: err:
if (req)
reply_handle(req, flags, 0, NULL);
return -1; return -1;
} }