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r11917@catbus: nickm | 2007-02-24 03:18:52 -0500

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Fix another XXX012 in eventdns.c: tell the DNS request about malformed DNS replies.


svn:r9637
This commit is contained in:
Nick Mathewson 2007-02-24 08:18:59 +00:00
parent 9b07b1a463
commit cc64d1f111
2 changed files with 17 additions and 12 deletions
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2
ChangeLog
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@ -53,6 +53,8 @@ Changes in version 0.1.2.8-alpha - 2007-??-??
if we aren't. if we aren't.
- Make earlier entry guards _really_ get retried when the network comes - Make earlier entry guards _really_ get retried when the network comes
back online. back online.
- On a malformed DNS reply, always give an error to the corresponding
DNS request.
o Minor features (controller): o Minor features (controller):
- Warn the user when an application uses the obsolete binary v0 - Warn the user when an application uses the obsolete binary v0

27
src/or/eventdns.c
View File

@ -791,7 +791,7 @@ name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
return -1; return -1;
} }
// parses a raw request from a nameserver. // parses a raw reply from a nameserver.
static int static int
reply_parse(u8 *packet, int length) { reply_parse(u8 *packet, int length) {
int j = 0; // index into packet int j = 0; // index into packet
@ -799,10 +799,11 @@ 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);
@ -815,16 +816,16 @@ reply_parse(u8 *packet, int length) {
(void) additional; /* suppress "unused variable" warnings. */ (void) additional; /* suppress "unused variable" warnings. */
req = request_find_from_trans_id(trans_id); req = request_find_from_trans_id(trans_id);
/* if no request, can't do anything. */
if (!req) return -1; if (!req) return -1;
// XXXX012 should the other return points also call reply_handle? -NM
memset(&reply, 0, sizeof(reply)); memset(&reply, 0, sizeof(reply));
/* if not an answer, it doesn't go with any of our requests. */
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
@ -843,7 +844,7 @@ 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
@ -866,13 +867,13 @@ 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;
@ -885,7 +886,7 @@ 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;
@ -895,13 +896,13 @@ 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;
@ -917,6 +918,8 @@ 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;
} }