* removed, various robustness fixes
*
* 2006 --jilles and nenolod
+ *
+ * Resend queries to other servers if the DNS server replies with an error or
+ * an invalid response. Also, avoid servers that return errors or invalid
+ * responses.
+ *
+ * October 2012 --mr_flea
*/
#include "stdinc.h"
static rb_fde_t *res_fd;
static rb_dlink_list request_list = { NULL, NULL, 0 };
-static int ns_timeout_count[IRCD_MAXNS];
+static int ns_failure_count[IRCD_MAXNS]; /* timeouts and invalid/failed replies */
static void rem_request(struct reslist *request);
static struct reslist *make_request(struct DNSQuery *query);
* res_ourserver(inp)
* looks up "inp" in irc_nsaddr_list[]
* returns:
- * 0 : not found
- * >0 : found
+ * server ID or -1 for not found
* author:
* paul vixie, 29may94
* revised for ircd, cryogen(stu) may03
+ * slightly modified for charybdis, mr_flea oct12
*/
static int res_ourserver(const struct rb_sockaddr_storage *inp)
{
for (ns = 0; ns < irc_nscount; ns++)
{
const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns];
+
+ if (srv->ss_family != inp->ss_family)
+ continue;
+
#ifdef RB_IPV6
v6 = (const struct sockaddr_in6 *)srv;
#endif
v4 = (const struct sockaddr_in *)srv;
/* could probably just memcmp(srv, inp, srv.ss_len) here
- * but we'll air on the side of caution - stu
+ * but we'll err on the side of caution - stu
*/
switch (srv->ss_family)
{
#ifdef RB_IPV6
- case AF_INET6:
- if (srv->ss_family == inp->ss_family)
- if (v6->sin6_port == v6in->sin6_port)
- if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
- sizeof(struct in6_addr)) == 0) ||
- (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
- sizeof(struct in6_addr)) == 0))
- {
- ns_timeout_count[ns] = 0;
- return 1;
- }
- break;
+ case AF_INET6:
+ if (v6->sin6_port == v6in->sin6_port)
+ if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
+ sizeof(struct in6_addr)) == 0) ||
+ (memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
+ sizeof(struct in6_addr)) == 0))
+ {
+ return ns;
+ }
+ break;
#endif
- case AF_INET:
- if (srv->ss_family == inp->ss_family)
- if (v4->sin_port == v4in->sin_port)
- if ((v4->sin_addr.s_addr == INADDR_ANY)
- || (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
- {
- ns_timeout_count[ns] = 0;
- return 1;
- }
- break;
- default:
- break;
+ case AF_INET:
+ if (v4->sin_port == v4in->sin_port)
+ if ((v4->sin_addr.s_addr == INADDR_ANY)
+ || (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
+ {
+ return ns;
+ }
+ break;
+ default:
+ break;
}
}
- return 0;
+ return -1;
}
/*
if (now >= timeout)
{
- if (--request->retries <= 0)
- {
- (*request->query->callback) (request->query->ptr, NULL);
- rem_request(request);
- continue;
- }
- else
- {
- ns_timeout_count[request->lastns]++;
- request->sentat = now;
- request->timeout += request->timeout;
- resend_query(request);
- }
+ ns_failure_count[request->lastns]++;
+ request->sentat = now;
+ request->timeout += request->timeout;
+ resend_query(request);
}
if ((next_time == 0) || timeout < next_time)
irc_res_init();
for (i = 0; i < irc_nscount; i++)
- ns_timeout_count[i] = 0;
+ ns_failure_count[i] = 0;
if (res_fd == NULL)
{
request->timeout = 4; /* start at 4 and exponential inc. */
request->query = query;
+ /*
+ * generate a unique id
+ * NOTE: we don't have to worry about converting this to and from
+ * network byte order, the nameserver does not interpret this value
+ * and returns it unchanged
+ *
+ * we generate an id per request now (instead of per send) to allow
+ * late replies to be used.
+ */
+#ifdef HAVE_LRAND48
+ do
+ {
+ request->id = (request->id + lrand48()) & 0xffff;
+ } while (find_id(request->id));
+#else
+ int k = 0;
+ struct timeval tv;
+ gettimeofday(&tv, NULL);
+ do
+ {
+ request->id = (request->id + k + tv.tv_usec) & 0xffff;
+ k++;
+ } while (find_id(request->id));
+#endif /* HAVE_LRAND48 */
+
rb_dlinkAdd(request, &request->node, &request_list);
return request;
for (i = 0; i < irc_nscount; i++)
{
ns = (i + rcount - 1) % irc_nscount;
- if (ns_timeout_count[ns] && retrycnt % retryfreq(ns_timeout_count[ns]))
+ if (ns_failure_count[ns] && retrycnt % retryfreq(ns_failure_count[ns]))
continue;
if (sendto(rb_get_fd(res_fd), msg, len, 0,
(struct sockaddr *)&(irc_nsaddr_list[ns]),
for (i = 0; i < irc_nscount; i++)
{
ns = (i + rcount - 1) % irc_nscount;
- if (!ns_timeout_count[ns])
+ if (!ns_failure_count[ns])
continue;
if (sendto(rb_get_fd(res_fd), msg, len, 0,
(struct sockaddr *)&(irc_nsaddr_list[ns]),
irc_res_mkquery(request->queryname, C_IN, request->type, (unsigned char *)buf, sizeof(buf))) > 0)
{
HEADER *header = (HEADER *) buf;
-#ifndef HAVE_LRAND48
- int k = 0;
- struct timeval tv;
-#endif
- /*
- * generate an unique id
- * NOTE: we don't have to worry about converting this to and from
- * network byte order, the nameserver does not interpret this value
- * and returns it unchanged
- */
-#ifdef HAVE_LRAND48
- do
- {
- header->id = (header->id + lrand48()) & 0xffff;
- } while (find_id(header->id));
-#else
- gettimeofday(&tv, NULL);
- do
- {
- header->id = (header->id + k + tv.tv_usec) & 0xffff;
- k++;
- } while (find_id(header->id));
-#endif /* HAVE_LRAND48 */
- request->id = header->id;
+ header->id = request->id;
++request->sends;
ns = send_res_msg(buf, request_len, request->sends);
static void resend_query(struct reslist *request)
{
+ if (--request->retries <= 0)
+ {
+ (*request->query->callback) (request->query->ptr, NULL);
+ rem_request(request);
+ return;
+ }
+
switch (request->type)
{
case T_PTR:
int answer_count;
socklen_t len = sizeof(struct rb_sockaddr_storage);
struct rb_sockaddr_storage lsin;
+ int ns;
rc = recvfrom(rb_get_fd(F), buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len);
/*
* check against possibly fake replies
*/
- if (!res_ourserver(&lsin))
+ ns = res_ourserver(&lsin);
+ if (ns == -1)
return 1;
+ if (ns != request->lastns)
+ {
+ /*
+ * We'll accept the late reply, but penalize it a little more to make
+ * sure a laggy server doesn't end up favored.
+ */
+ ns_failure_count[ns] += 3;
+ }
+
+
if (!check_question(request, header, buf, buf + rc))
return 1;
if ((header->rcode != NO_ERRORS) || (header->ancount == 0))
{
- if (NXDOMAIN == header->rcode)
+ /*
+ * RFC 2136 states that in the event of a server returning SERVFAIL
+ * or NOTIMP, the request should be resent to the next server.
+ * Additionally, if the server refuses our query, resend it as well.
+ * -- mr_flea
+ */
+ if (SERVFAIL == header->rcode || NOTIMP == header->rcode ||
+ REFUSED == header->rcode)
{
- (*request->query->callback) (request->query->ptr, NULL);
- rem_request(request);
+ ns_failure_count[ns]++;
+ resend_query(request);
}
else
{
/*
- * If a bad error was returned, we stop here and dont send
- * send any more (no retries granted).
+ * Either a fatal error was returned or no answer. Cancel the
+ * request.
*/
+ if (NXDOMAIN == header->rcode)
+ {
+ /* If the rcode is NXDOMAIN, treat it as a good response. */
+ ns_failure_count[ns] /= 4;
+ }
(*request->query->callback) (request->query->ptr, NULL);
rem_request(request);
}
return 1;
}
/*
- * If this fails there was an error decoding the received packet,
- * give up. -- jilles
+ * If this fails there was an error decoding the received packet.
+ * -- jilles
*/
answer_count = proc_answer(request, header, buf, buf + rc);
if (request->name == NULL)
{
/*
- * got a PTR response with no name, something bogus is happening
- * don't bother trying again, the client address doesn't resolve
+ * Got a PTR response with no name, something strange is
+ * happening. Try another DNS server.
*/
- (*request->query->callback) (request->query->ptr, reply);
- rem_request(request);
+ ns_failure_count[ns]++;
+ resend_query(request);
return 1;
}
/*
* Lookup the 'authoritative' name that we were given for the
* ip#.
- *
*/
#ifdef RB_IPV6
if (request->addr.ss_family == AF_INET6)
rb_free(reply);
rem_request(request);
}
+
+ ns_failure_count[ns] /= 4;
}
else
{
- /* couldn't decode, give up -- jilles */
- (*request->query->callback) (request->query->ptr, NULL);
- rem_request(request);
+ /* Invalid or corrupt reply - try another resolver. */
+ ns_failure_count[ns]++;
+ resend_query(request);
}
return 1;
}
ipaddr, sizeof ipaddr))
rb_strlcpy(ipaddr, "?", sizeof ipaddr);
sendto_one_numeric(source_p, RPL_STATSDEBUG,
- "A %s %d", ipaddr, ns_timeout_count[i]);
+ "A %s %d", ipaddr, ns_failure_count[i]);
}
}
projects / solanum.git / blobdiff