call: check address-family of incoming SDP offer

this fixes #79

2 files changed, 49 insertions, 2 deletions

diff --git a/src/call.c b/src/call.c
index 144e25b..a8d1cd7 100644
--- a/src/call.c
+++ b/src/call.c
@@ -1217,7 +1217,7 @@ static bool have_common_audio_codecs(const struct call *call)
 	if (!sc)
 		return false;
 
-	ac = sc->data;
+	ac = sc->data;  /* note: this will exclude telephone-event */
 
 	return ac != NULL;
 }
@@ -1247,6 +1247,8 @@ int call_accept(struct call *call, struct sipsess_sock *sess_sock,
 	}
 
 	if (got_offer) {
+		struct sdp_media *m;
+		const struct sa *raddr;
 
 		err = sdp_decode(call->sdp, msg->mb, true);
 		if (err)
@@ -1254,6 +1256,30 @@ int call_accept(struct call *call, struct sipsess_sock *sess_sock,
 
 		call->got_offer = true;
 
+		/*
+		 * Each media description in the SDP answer MUST
+		 * use the same network type as the corresponding
+		 * media description in the offer.
+		 *
+		 * See RFC 6157
+		 */
+		m = stream_sdpmedia(audio_strm(call->audio));
+		raddr = sdp_media_raddr(m);
+
+		if (sa_af(raddr) != call->af) {
+			info("call: incompatible address-family"
+			     " (local=%s, remote=%s)\n",
+			     net_af2name(call->af),
+			     net_af2name(sa_af(raddr)));
+
+			sip_treply(NULL, uag_sip(), msg,
+				   488, "Not Acceptable Here");
+
+			call_event_handler(call, CALL_EVENT_CLOSED,
+					   "Wrong address family");
+			return 0;
+		}
+
 		/* Check if we have any common audio codecs, after
 		 * the SDP offer has been parsed
 		 */
diff --git a/src/ua.c b/src/ua.c
index 7aeabd5..424a2a1 100644
--- a/src/ua.c
+++ b/src/ua.c
@@ -34,6 +34,7 @@ struct ua {
 	char *cuser;                 /**< SIP Contact username               */
 	char *pub_gruu;              /**< SIP Public GRUU                    */
 	int af;                      /**< Preferred Address Family           */
+	int af_media;
 	enum presence_status my_status; /**< Presence Status                 */
 };
 
@@ -428,6 +429,7 @@ static int ua_call_alloc(struct call **callp, struct ua *ua,
 			 struct call *xcall, const char *local_uri)
 {
 	struct call_prm cprm;
+	int af = AF_UNSPEC;
 	int err;
 
 	if (*callp) {
@@ -435,8 +437,18 @@ static int ua_call_alloc(struct call **callp, struct ua *ua,
 		return EALREADY;
 	}
 
+	/* 1. if AF_MEDIA is set, we prefer it
+	 * 2. otherwise fall back to SIP AF
+	 */
+	if (ua->af_media) {
+		af = ua->af_media;
+	}
+	else if (ua->af) {
+		af = ua->af;
+	}
+
 	cprm.vidmode = vidmode;
-	cprm.af      = ua->af;
+	cprm.af      = af;
 
 	err = call_alloc(callp, conf_config(), &ua->calls,
 			 ua->acc->dispname,
@@ -1842,3 +1854,12 @@ struct ua *uag_current(void)
 
 	return uag.ua_cur;
 }
+
+
+void ua_set_media_af(struct ua *ua, int af_media)
+{
+	if (!ua)
+		return;
+
+	ua->af_media = af_media;
+}