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Match the query in DNS replies to the query in the request; from Vsevolod Stakhov

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svn:r930
This commit is contained in:
Niels Provos 2008-08-30 23:19:49 +00:00
parent c968eb3e01
commit a710d817ad
2 changed files with 33 additions and 14 deletions
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1
ChangeLog
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@ -122,6 +122,7 @@ Changes in current version:
o Fix off-by-one errors in devpoll; from Ian Bell o Fix off-by-one errors in devpoll; from Ian Bell
o Make event_add not change any state if it fails; reported by Ian Bell. o Make event_add not change any state if it fails; reported by Ian Bell.
o Fix a bug where headers arriving in multiple packets were not parsed; fix from Jiang Hong; test by me. o Fix a bug where headers arriving in multiple packets were not parsed; fix from Jiang Hong; test by me.
o Match the query in DNS replies to the query in the request; from Vsevolod Stakhov.
Changes in 1.4.0: Changes in 1.4.0:
o allow \r or \n individually to separate HTTP headers instead of the standard "\r\n"; from Charles Kerr. o allow \r or \n individually to separate HTTP headers instead of the standard "\r\n"; from Charles Kerr.

46
evdns.c
View File

@ -711,7 +711,10 @@ reply_callback(struct evdns_request *const req, u32 ttl, u32 err, struct reply *
static void static void
reply_handle(struct evdns_request *const req, u16 flags, u32 ttl, struct reply *reply) { reply_handle(struct evdns_request *const req, u16 flags, u32 ttl, struct reply *reply) {
int error; int error;
static const int error_codes[] = {DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, DNS_ERR_NOTIMPL, DNS_ERR_REFUSED}; static const int error_codes[] = {
DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST,
DNS_ERR_NOTIMPL, DNS_ERR_REFUSED
};
if (flags & 0x020f || !reply || !reply->have_answer) { if (flags & 0x020f || !reply || !reply->have_answer) {
/* there was an error */ /* there was an error */
@ -739,9 +742,10 @@ reply_handle(struct evdns_request *const req, u16 flags, u32 ttl, struct reply *
} }
break; break;
case DNS_ERR_SERVERFAILED: case DNS_ERR_SERVERFAILED:
/* rcode 2 (servfailed) sometimes means "we are broken" and /* rcode 2 (servfailed) sometimes means "we
* sometimes (with some binds) means "that request was very * are broken" and sometimes (with some binds)
* confusing." Treat this as a timeout, not a failure. * means "that request was very confusing."
* Treat this as a timeout, not a failure.
*/ */
log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver %s; " log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver %s; "
"will allow the request to time out.", "will allow the request to time out.",
@ -753,10 +757,13 @@ reply_handle(struct evdns_request *const req, u16 flags, u32 ttl, struct reply *
} }
if (req->search_state && req->request_type != TYPE_PTR) { if (req->search_state && req->request_type != TYPE_PTR) {
/* if we have a list of domains to search in, try the next one */ /* if we have a list of domains to search in,
* try the next one */
if (!search_try_next(req)) { if (!search_try_next(req)) {
/* a new request was issued so this request is finished and */ /* a new request was issued so this
/* the user callback will be made when that request (or a */ * request is finished and */
/* the user callback will be made when
* that request (or a */
/* child of it) finishes. */ /* child of it) finishes. */
request_finished(req, &REQ_HEAD(req->base, req->trans_id)); request_finished(req, &REQ_HEAD(req->base, req->trans_id));
return; return;
@ -833,10 +840,10 @@ name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
/* parses a raw request from a nameserver */ /* parses a raw request from a nameserver */
static int static int
reply_parse(struct evdns_base *base, u8 *packet, int length) { reply_parse(struct evdns_base *base, u8 *packet, int length) {
int j = 0; /* index into packet */ int j = 0, k = 0; /* index into packet */
u16 _t; /* used by the macros */ u16 _t; /* used by the macros */
u32 _t32; /* used by the macros */ u32 _t32; /* used by the macros */
char tmp_name[256]; /* used by the macros */ char tmp_name[256], cmp_name[256]; /* used by the macros */
u16 trans_id, questions, answers, authority, additional, datalength; u16 trans_id, questions, answers, authority, additional, datalength;
u16 flags = 0; u16 flags = 0;
@ -870,10 +877,21 @@ reply_parse(struct evdns_base *base, u8 *packet, int length) {
/* This macro skips a name in the DNS reply. */ /* This macro skips a name in the DNS reply. */
#define SKIP_NAME \ #define SKIP_NAME \
do { tmp_name[0] = '\0'; \ do { tmp_name[0] = '\0'; \
if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) \ if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)\
goto err; \ goto err; \
} while(0); } while(0)
#define TEST_NAME \
do { tmp_name[0] = '\0'; \
cmp_name[0] = '\0'; \
k = j; \
if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)\
goto err; \
if (name_parse(req->request, req->request_len, &k, cmp_name, sizeof(cmp_name))<0) \
goto err; \
if (memcmp(tmp_name, cmp_name, strlen (tmp_name)) != 0) \
return (-1); /* we ignore mismatching names */ \
} while(0)
reply.type = req->request_type; reply.type = req->request_type;
@ -882,7 +900,7 @@ reply_parse(struct evdns_base *base, u8 *packet, int length) {
/* the question looks like /* the question looks like
* <label:name><u16:type><u16:class> * <label:name><u16:type><u16:class>
*/ */
SKIP_NAME; TEST_NAME;
j += 4; j += 4;
if (j > length) goto err; if (j > length) goto err;
} }