fix unicast response port and timeout

Responses to One-Shot Multicast DNS Queries (as in RFC 6762 5.1)
with CLASS_UNICAST set should be sent back to the port of the
client and not to 5353. In addition timeouts should be ignored.

Signed-off-by: Tobias Waldvogel <tobias.waldvogel@gmail.com>

4 files changed, 9 insertions, 7 deletions

diff --git a/dns.c b/dns.c
index f6f0be5..e849396 100644
--- a/dns.c
+++ b/dns.c
@@ -357,12 +357,13 @@ static int parse_answer(struct interface *iface, struct sockaddr *from,
 static void
 parse_question(struct interface *iface, struct sockaddr *from, char *name, struct dns_question *q)
 {
+	int is_unicast = (q->class & CLASS_UNICAST) != 0;
 	struct sockaddr *to = NULL;
 	struct hostname *h;
 	char *host;
 
 	/* TODO: Multicast if more than one quarter of TTL has passed */
-	if (q->class & CLASS_UNICAST) {
+	if (is_unicast) {
 		to = from;
 		if (interface_multicast(iface))
 			iface = interface_get(iface->name, iface->type | SOCKTYPE_BIT_UNICAST);
@@ -375,7 +376,7 @@ parse_question(struct interface *iface, struct sockaddr *from, char *name, struc
 		if (!strcmp(name, mdns_hostname_local)) {
 			dns_reply_a(iface, to, announce_ttl, NULL);
 			dns_reply_a_additional(iface, to, announce_ttl);
-			service_reply(iface, to, NULL, NULL, announce_ttl);
+			service_reply(iface, to, NULL, NULL, announce_ttl, is_unicast);
 		}
 		break;
 
@@ -386,14 +387,14 @@ parse_question(struct interface *iface, struct sockaddr *from, char *name, struc
 			service_announce_services(iface, to, announce_ttl);
 		} else {
 			if (name[0] == '_') {
-				service_reply(iface, to, NULL, name, announce_ttl);
+				service_reply(iface, to, NULL, name, announce_ttl, is_unicast);
 			} else {
 				/* First dot separates instance name from the rest */
 				char *dot = strchr(name, '.');
 
 				if (dot) {
 					*dot = '\0';
-					service_reply(iface, to, name, dot + 1, announce_ttl);
+					service_reply(iface, to, name, dot + 1, announce_ttl, is_unicast);
 					*dot = '.';
 				}
 			}
diff --git a/interface.c b/interface.c
index ad25b39..944666f 100644
--- a/interface.c
+++ b/interface.c
@@ -84,6 +84,7 @@ interface_send_packet4(struct interface *iface, struct sockaddr_in *to, struct i
 			fprintf(stderr, "Ignoring IPv4 address for multicast interface\n");
 	} else {
 		a.sin_addr.s_addr = to->sin_addr.s_addr;
+		a.sin_port = to->sin_port;
 	}
 
 	return sendmsg(fd, &m, 0);
diff --git a/service.c b/service.c
index 1f81031..9d3767b 100644
--- a/service.c
+++ b/service.c
@@ -144,7 +144,7 @@ service_reply_single(struct interface *iface, struct sockaddr *to, struct servic
 }
 
 void
-service_reply(struct interface *iface, struct sockaddr *to, const char *instance, const char *service_domain, int ttl)
+service_reply(struct interface *iface, struct sockaddr *to, const char *instance, const char *service_domain, int ttl, int force)
 {
 	struct service *s;
 
@@ -153,7 +153,7 @@ service_reply(struct interface *iface, struct sockaddr *to, const char *instance
 			continue;
 		if (service_domain && strcmp(s->service, service_domain))
 			continue;
-		service_reply_single(iface, to, s, ttl, 0);
+		service_reply_single(iface, to, s, ttl, force);
 	}
 }
 
diff --git a/service.h b/service.h
index ea2a6ed..6cae5bb 100644
--- a/service.h
+++ b/service.h
@@ -41,7 +41,7 @@ extern struct vlist_tree announced_services;
 
 extern void service_init(int announce);
 extern void service_cleanup(void);
-extern void service_reply(struct interface *iface, struct sockaddr *to, const char *instance, const char *service_domain, int ttl);
+extern void service_reply(struct interface *iface, struct sockaddr *to, const char *instance, const char *service_domain, int ttl, int force);
 extern void service_announce_services(struct interface *iface, struct sockaddr *to, int ttl);
 extern void service_update(struct vlist_tree *tree, struct vlist_node *node_new, struct vlist_node *node_old);