dtmf: Forward DTMF from MNCC to SIP

We are not using the RTP telephony-event here but the older dtmf
relay. We also only have a fixed DTMF duration for now.

Change-Id: Icf770fae89f7aedf6eba9a119db9b8acc7f938df

src/call.h

@@ -67,6 +67,11 @@ struct call_leg {
 	 * by the application to release the call.
 	 */
 	void (*release_call)(struct call_leg *);
+
+	/**
+	 * A DTMF key was entered. Forward it.
+	 */
+	void (*dtmf)(struct call_leg *, int keypad);
 };
 
 enum sip_cc_state {

src/mncc.c

@@ -632,6 +632,7 @@ static void check_dtmf_start(struct mncc_connection *conn, char *buf, int rc)
 	struct gsm_mncc out_mncc = { 0, };
 	struct gsm_mncc *data;
 	struct mncc_call_leg *leg;
+	struct call_leg *other_leg;
 
 	leg = find_leg(conn, buf, rc, &data);
 	if (!leg)
@@ -639,6 +640,10 @@ static void check_dtmf_start(struct mncc_connection *conn, char *buf, int rc)
 
 	LOGP(DMNCC, LOGL_DEBUG, "leg(%u) DTMF key=%c\n", leg->callref, data->keypad);
 
+	other_leg = call_leg_other(&leg->base);
+	if (other_leg && other_leg->dtmf)
+		other_leg->dtmf(other_leg, data->keypad);
+
 	mncc_fill_header(&out_mncc, MNCC_START_DTMF_RSP, leg->callref);
 	out_mncc.fields |= MNCC_F_KEYPAD;
 	out_mncc.keypad = data->keypad;

src/sip.c

@@ -37,6 +37,7 @@ extern void *tall_mncc_ctx;
 static void sip_release_call(struct call_leg *_leg);
 static void sip_ring_call(struct call_leg *_leg);
 static void sip_connect_call(struct call_leg *_leg);
+static void sip_dtmf_call(struct call_leg *_leg, int keypad);
 
 static void call_progress(struct sip_call_leg *leg, const sip_t *sip)
 {
@@ -131,6 +132,7 @@ static void new_call(struct sip_agent *agent, nua_handle_t *nh,
 	leg->base.release_call = sip_release_call;
 	leg->base.ring_call = sip_ring_call;
 	leg->base.connect_call = sip_connect_call;
+	leg->base.dtmf = sip_dtmf_call;
 	leg->agent = agent;
 	leg->nua_handle = nh;
 	nua_handle_bind(nh, leg);
@@ -288,6 +290,22 @@ static void sip_connect_call(struct call_leg *_leg)
 	talloc_free(sdp);
 }
 
+static void sip_dtmf_call(struct call_leg *_leg, int keypad)
+{
+	struct sip_call_leg *leg;
+	char *buf;
+
+	OSMO_ASSERT(_leg->type == CALL_TYPE_SIP);
+	leg = (struct sip_call_leg *) _leg;
+
+	buf = talloc_asprintf(leg, "Signal=%c\nDuration=160\n", keypad);
+	nua_info(leg->nua_handle,
+		NUTAG_MEDIA_ENABLE(0),
+		SIPTAG_CONTENT_TYPE_STR("application/dtmf-relay"),
+		SIPTAG_PAYLOAD_STR(buf), TAG_END());
+	talloc_free(buf);
+}
+
 static int send_invite(struct sip_agent *agent, struct sip_call_leg *leg,
 			const char *calling_num, const char *called_num)
 {
@@ -334,6 +352,7 @@ int sip_create_remote_leg(struct sip_agent *agent, struct call *call)
 	leg->base.type = CALL_TYPE_SIP;
 	leg->base.call = call;
 	leg->base.release_call = sip_release_call;
+	leg->base.dtmf = sip_dtmf_call;
 	leg->agent = agent;
 
 	leg->nua_handle = nua_handle(agent->nua, leg, TAG_END());