Randomize source port to make a DNS request.

1 files changed, 59 insertions, 13 deletions

diff --git a/src/dns.c b/src/dns.c
index b479ac576..a6e87aa32 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -763,11 +763,42 @@ make_spf_req (struct rspamd_dns_request *req, const gchar *name)
 	req->requested_name = name;
 }
 
+static guint16
+rspamd_bind_to_random_port (int sock)
+{
+	union sa_union su;
+	socklen_t slen = sizeof (su);
+	guint16 ret = 0;
+	const int max_retries = 10;
+	int retries = 0;
+
+	if (getsockname (sock, &su.sa, &slen) != -1) {
+
+		while (retries < max_retries) {
+			ret = g_random_int_range (1024, G_MAXUINT16 - 1);
+			if (su.sa.sa_family == AF_INET) {
+				su.s4.sin_port = htons (ret);
+			}
+			else if (su.sa.sa_family == AF_INET6) {
+				su.s6.sin6_port = htons (ret);
+			}
+			if (bind (sock, &su.sa, slen) != -1) {
+				return ret;
+			}
+			retries ++;
+		}
+	}
+
+	return 0;
+}
+
 static gint
 send_dns_request (struct rspamd_dns_request *req)
 {
 	gint r;
 
+	req->port = rspamd_bind_to_random_port (req->sock);
+	req->key = ((guint32)req->port) << 16 + req->id;
 	r = send (req->sock, req->packet, req->pos, 0);
 	if (r == -1) {
 		if (errno == EAGAIN) {
@@ -800,7 +831,7 @@ dns_fin_cb (gpointer arg)
 	struct rspamd_dns_request *req = arg;
 	
 	event_del (&req->timer_event);
-	g_hash_table_remove (req->resolver->requests, &req->id);
+	g_hash_table_remove (req->resolver->requests, &req->key);
 }
 
 static guint8 *
@@ -1188,7 +1219,8 @@ dns_parse_rr (guint8 *in, union rspamd_reply_element *elt, guint8 **pos, struct
 
 static gboolean
 dns_parse_reply (guint8 *in, gint r, struct rspamd_dns_resolver *resolver,
-		struct rspamd_dns_request **req_out, struct rspamd_dns_reply **_rep)
+		guint16 port, struct rspamd_dns_request **req_out,
+		struct rspamd_dns_reply **_rep)
 {
 	struct dns_header *header = (struct dns_header *)in;
 	struct rspamd_dns_request      *req;
@@ -1196,6 +1228,7 @@ dns_parse_reply (guint8 *in, gint r, struct rspamd_dns_resolver *resolver,
 	union rspamd_reply_element     *elt;
 	guint8                         *pos;
 	guint16                         id;
+	guint32                         key;
 	gint                            i, t;
 	
 	/* First check header fields */
@@ -1206,7 +1239,8 @@ dns_parse_reply (guint8 *in, gint r, struct rspamd_dns_resolver *resolver,
 
 	/* Now try to find corresponding request */
 	id = header->qid;
-	if ((req = g_hash_table_lookup (resolver->requests, &id)) == NULL) {
+	key = ((guint32)port) << 16 + id;
+	if ((req = g_hash_table_lookup (resolver->requests, &key)) == NULL) {
 		/* No such requests found */
 		return FALSE;
 	}
@@ -1282,13 +1316,22 @@ dns_read_cb (gint fd, short what, void *arg)
 	gint                            r;
 	struct rspamd_dns_reply        *rep;
 	guint8                          in[UDP_PACKET_SIZE];
+	union sa_union                  su;
+	socklen_t                       slen = sizeof (su);
+	guint16                         port = 0;
 
 	/* This function is called each time when we have data on one of server's sockets */
 	
 	/* First read packet from socket */
-	r = read (fd, in, sizeof (in));
+	r = recvfrom (fd, in, sizeof (in), 0, &su.sa, &slen);
 	if (r > (gint)(sizeof (struct dns_header) + sizeof (struct dns_query))) {
-		if (dns_parse_reply (in, r, resolver, &req, &rep)) {
+		if (su.sa.sa_family == AF_INET) {
+			port = ntohs (su.s4.sin_port);
+		}
+		else if (su.sa.sa_family == AF_INET6) {
+			port = ntohs (su.s6.sin6_port);
+		}
+		if (dns_parse_reply (in, r, resolver, port, &req, &rep)) {
 			/* Decrease errors count */
 			if (rep->request->resolver->errors > 0) {
 				rep->request->resolver->errors --;
@@ -1345,7 +1388,8 @@ dns_timer_cb (gint fd, short what, void *arg)
 	}
 	
 	if (req->server->sock == -1) {
-		req->server->sock =  make_universal_socket (req->server->name, dns_port, SOCK_DGRAM, TRUE, FALSE, FALSE);
+		req->server->sock =  make_universal_socket (req->server->name,
+				dns_port, SOCK_DGRAM, TRUE, FALSE, FALSE);
 	}
 	req->sock = req->server->sock;
 
@@ -1417,7 +1461,7 @@ dns_retransmit_handler (gint fd, short what, void *arg)
 			evtimer_add (&req->timer_event, &req->tv);
 
 			/* Add request to hash table */
-			g_hash_table_insert (req->resolver->requests, &req->id, req);
+			g_hash_table_insert (req->resolver->requests, &req->key, req);
 			register_async_event (req->session, (event_finalizer_t)dns_fin_cb, req, g_quark_from_static_string ("dns resolver"));
 		}
 	}
@@ -1506,7 +1550,8 @@ make_dns_request (struct rspamd_dns_resolver *resolver,
 	}
 	
 	if (req->server->sock == -1) {
-		req->server->sock =  make_universal_socket (req->server->name, dns_port, SOCK_DGRAM, TRUE, FALSE, FALSE);
+		req->server->sock =  make_universal_socket (req->server->name,
+				dns_port, SOCK_DGRAM, TRUE, FALSE, FALSE);
 	}
 	req->sock = req->server->sock;
 
@@ -1527,13 +1572,13 @@ make_dns_request (struct rspamd_dns_resolver *resolver,
 		evtimer_add (&req->timer_event, &req->tv);
 
 		/* Add request to hash table */
-		while (g_hash_table_lookup (resolver->requests, &req->id)) {
+		while (g_hash_table_lookup (resolver->requests, &req->key)) {
 			/* Check for unique id */
 			header = (struct dns_header *)req->packet;
 			header->qid = dns_k_permutor_step (resolver->permutor);
 			req->id = header->qid;
 		}
-		g_hash_table_insert (resolver->requests, &req->id, req);
+		g_hash_table_insert (resolver->requests, &req->key, req);
 		register_async_event (session, (event_finalizer_t)dns_fin_cb, req, g_quark_from_static_string ("dns resolver"));
 	}
 	else if (r == -1) {
@@ -1595,13 +1640,13 @@ parse_resolv_conf (struct rspamd_dns_resolver *resolver)
 static gboolean
 dns_id_equal (gconstpointer v1, gconstpointer v2)
 {
-	return *((const guint16*) v1) == *((const guint16*) v2);
+	return *((const guint32*) v1) == *((const guint32*) v2);
 }
 
 static guint
 dns_id_hash (gconstpointer v)
 {
-	return *(const guint16 *) v;
+	return *(const guint32 *) v;
 }
 
 
@@ -1692,7 +1737,8 @@ dns_resolver_init (struct event_base *ev_base, struct config_file *cfg)
 	/* Now init all servers */
 	for (i = 0; i < new->servers_num; i ++) {
 		serv = &new->servers[i];
-		serv->sock = make_universal_socket (serv->name, dns_port, SOCK_DGRAM, TRUE, FALSE, FALSE);
+		serv->sock = make_universal_socket (serv->name, dns_port,
+				SOCK_DGRAM, TRUE, FALSE, FALSE);
 		if (serv->sock == -1) {
 			msg_warn ("cannot create socket to server %s", serv->name);
 		}