Description: Add support for DTLS retransmission
Author: NITESH BANSAL <nbansal@voxbone.com>
--- a/res/res_rtp_asterisk.c
+++ b/res/res_rtp_asterisk.c
@@ -301,6 +301,7 @@
 	unsigned int dtls_failure:1; /*!< Failure occurred during DTLS negotiation */
 	unsigned int rekey; /*!< Interval at which to renegotiate and rekey */
 	int rekeyid; /*!< Scheduled item id for rekeying */
+	int dtlstimerid; /*!< Scheduled item id for DTLS retransmission for RTP */
 #endif
 };
 
@@ -1588,6 +1589,31 @@
 	/* We just use the verify_callback to request a certificate from the client */
 	return 1;
 }
+
+static int dtls_srtp_handle_timeout(const void *data)
+{
+	struct ast_rtp_instance *instance = (struct ast_rtp_instance *)data;
+	struct ast_rtp *rtp = ast_rtp_instance_get_data(instance);
+
+	rtp->dtlstimerid = -1;
+
+	if (rtp && rtp->ssl)
+	{
+		DTLSv1_handle_timeout(rtp->ssl);
+	}
+
+	if (rtp->rtcp && rtp->rtcp->ssl)
+	{
+		DTLSv1_handle_timeout(rtp->rtcp->ssl);
+	}
+
+	dtls_srtp_check_pending(instance, rtp);
+
+	ao2_ref(instance, -1);
+
+	return 0;
+}
+
 /*SRTP_DTLS */
 static void dtls_srtp_check_pending(struct ast_rtp_instance *instance, struct ast_rtp *rtp)
 {
@@ -1595,6 +1621,7 @@
 	if (rtp->ssl)
 	{
 		size_t pending = BIO_ctrl_pending(rtp->write_bio);
+		struct timeval dtls_timeout; /* timeout on DTLS  */
 
 		if (pending > 0) {
 			char outgoing[pending];
@@ -1623,6 +1650,24 @@
 			}
 			/*SRTP_DTLS */
 
+			/* Stop existing DTLS timer if running */
+			if (rtp->dtlstimerid > -1)
+			{
+				AST_SCHED_DEL_UNREF(rtp->sched, rtp->dtlstimerid, ao2_ref(instance, -1));
+				rtp->dtlstimerid = -1;
+			}
+
+			if (DTLSv1_get_timeout(rtp->ssl, &dtls_timeout))
+			{
+				int timeout = dtls_timeout.tv_sec * 1000 + dtls_timeout.tv_usec/1000;
+				ao2_ref(instance, +1);
+				if ((rtp->dtlstimerid = ast_sched_add(rtp->sched, timeout, dtls_srtp_handle_timeout, instance)) < 0)
+				{
+					ao2_ref(instance, -1);
+					ast_log(LOG_WARNING, "scheduling DTLS retransmission for RTP instance [%p] failed.\n", instance);
+				}
+			}
+
 			__rtp_sendto(instance, outgoing, out, 0, &remote_address, 0, &ice, 0);
 			/*SRTP_DTLS */
 			if(dtlsdebug)
@@ -1689,6 +1734,7 @@
 	return 0;
 }
 
+
 static int dtls_srtp_setup(struct ast_rtp *rtp, struct ast_srtp *srtp, struct ast_rtp_instance *instance)
 {
 	unsigned char material[SRTP_MASTER_LEN * 2];
@@ -2374,6 +2420,7 @@
 
 #ifdef HAVE_OPENSSL_SRTP
 	rtp->rekeyid = -1;
+	rtp->dtlstimerid = -1;
 	rtp->local_fingerprint_type = AST_RTP_DTLS_HASH_NONE;
 	rtp->remote_fingerprint_type = AST_RTP_DTLS_HASH_NONE;
 
@@ -4738,6 +4785,7 @@
 
 #ifdef HAVE_OPENSSL_SRTP
 	AST_SCHED_DEL_UNREF(rtp->sched, rtp->rekeyid, ao2_ref(instance, -1));
+	AST_SCHED_DEL_UNREF(rtp->sched, rtp->dtlstimerid, ao2_ref(instance, -1));
 #endif
 
 	if (rtp->rtcp && rtp->rtcp->schedid > 0) {