Change in ...osmo-sip-connector[master]: Handle SIP re-INVITEs

[keith]

keith has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-sip-connector/+/14994


Change subject: Handle SIP re-INVITEs
......................................................................

Handle SIP re-INVITEs

SIP end points can send periodic re-INVITES. Previous to this commit,
the osmo-sip-connector would send a new call SETUP to the MSC for each
re-INVITE.

Add a function to find if we already handle this call based on the nua handle.
Use this function to detect and respond with an ACK to re-INVITES.

Add a function to extract the media mode from the SDP.
In the case the re-INVITE has a=sendonly (HOLD) respond with a=recvonly

Change-Id: I4083ed50d0cf1b302b80354fe0c2b73fc6e14fed
---
M src/sdp.c
M src/sdp.h
M src/sip.c
3 files changed, 86 insertions(+), 3 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-sip-connector refs/changes/94/14994/1

diff --git a/src/sdp.c b/src/sdp.c
index 93e0c7f..d1d4777 100644
--- a/src/sdp.c
+++ b/src/sdp.c
@@ -32,6 +32,36 @@
 
 #include <string.h>
 
+sdp_mode_t sdp_mode(const sip_t *sip) {
+
+	const char *sdp_data;
+	sdp_parser_t *parser;
+	sdp_session_t *sdp;
+
+	if (!sip->sip_payload || !sip->sip_payload->pl_data) {
+		LOGP(DSIP, LOGL_ERROR, "No SDP file\n");
+		return false;
+	}
+
+	sdp_data = sip->sip_payload->pl_data;
+	parser = sdp_parse(NULL, sdp_data, strlen(sdp_data), sdp_f_mode_0000);
+	if (!parser) {
+		LOGP(DSIP, LOGL_ERROR, "Failed to parse SDP\n");
+		return false;
+	}
+
+	sdp = sdp_session(parser);
+	if (!sdp) {
+		LOGP(DSIP, LOGL_ERROR, "No sdp session\n");
+		sdp_parser_free(parser);
+		return false;
+	}
+
+	if (!sdp->sdp_media || !sdp->sdp_media->m_mode)
+		return sdp_sendrecv;
+	return sdp->sdp_media->m_mode;
+}
+
 /*
  * We want to decide on the audio codec later but we need to see
  * if it is even including some of the supported ones.
diff --git a/src/sdp.h b/src/sdp.h
index 72ff6b7..80c6698 100644
--- a/src/sdp.h
+++ b/src/sdp.h
@@ -8,6 +8,7 @@
 struct sip_call_leg;
 struct call_leg;
 
+sdp_mode_t sdp_mode(const sip_t *sip);
 bool sdp_screen_sdp(const sip_t *sip);
 bool sdp_extract_sdp(struct sip_call_leg *leg, const sip_t *sip, bool any_codec);
 
diff --git a/src/sip.c b/src/sip.c
index 21401c6..b5f856a 100644
--- a/src/sip.c
+++ b/src/sip.c
@@ -41,6 +41,27 @@
 static void sip_connect_call(struct call_leg *_leg);
 static void sip_dtmf_call(struct call_leg *_leg, int keypad);
 
+/* Find a SIP Call leg by given nua_handle */
+static struct sip_call_leg *sip_find_leg(nua_handle_t *nh)
+{
+	struct call *call;
+
+	llist_for_each_entry(call, &g_call_list, entry) {
+		if (call->initial && call->initial->type == CALL_TYPE_SIP) {
+			struct sip_call_leg *leg = (struct sip_call_leg *) call->initial;
+			if (leg->nua_handle == nh)
+				return leg;
+		}
+		if (call->remote && call->remote->type == CALL_TYPE_SIP) {
+			struct sip_call_leg *leg = (struct sip_call_leg *) call->remote;
+			if (leg->nua_handle == nh)
+				return leg;
+		}
+	}
+
+	return NULL;
+}
+
 static void call_progress(struct sip_call_leg *leg, const sip_t *sip, int status)
 {
 	struct call_leg *other = call_leg_other(&leg->base);
@@ -149,6 +170,32 @@
 			talloc_strdup(leg, to));
 }
 
+static void sip_handle_reinvite(struct sip_call_leg *leg, nua_handle_t *nh, const sip_t *sip) {
+
+	char *sdp = NULL;
+
+	LOGP(DSIP, LOGL_NOTICE, "re-INVITE for call %s\n", sip->sip_call_id->i_id);
+	sdp_mode_t mode = sdp_mode(sip);
+	struct call_leg *other = call_leg_other(&leg->base);
+	if (mode == sdp_sendonly) {
+		LOGP(DSIP, LOGL_NOTICE, "SIP side puts call on HOLD\n");
+		sdp = sdp_create_file(leg, other, sdp_recvonly);
+		// TODO: Tell osmo-bts to stop sending RTP ?
+	} else {
+		// Regular re-INVITE. Just ACK.
+		sdp = sdp_create_file(leg, other, sdp_sendrecv);
+	}
+
+	LOGP(DSIP, LOGL_DEBUG, "Sending 200 response to re-INVITE for mode(%u)\n", mode);
+	nua_respond(nh, SIP_200_OK,
+		    NUTAG_MEDIA_ENABLE(0),
+		    SIPTAG_CONTENT_TYPE_STR("application/sdp"),
+		    SIPTAG_PAYLOAD_STR(sdp),
+		    TAG_END());
+	talloc_free(sdp);
+	return;
+}
+
 /* Sofia SIP definitions come with error code numbers and strings, this
  * map allows us to reuse the existing definitions.
  * The map is in priority order. The first matching entry found
@@ -270,10 +317,15 @@
 		if (other)
 			other->release_call(other);
 	} else if (event == nua_i_invite) {
-		/* new incoming leg */
+		/* new incoming leg or re-INVITE */
 
-		if (status == 100)
-			new_call((struct sip_agent *) magic, nh, sip);
+		if (status == 100) {
+			struct sip_call_leg *leg = sip_find_leg(nh);
+			if (leg)
+				sip_handle_reinvite(leg, nh, sip);
+			else
+				new_call((struct sip_agent *) magic, nh, sip);
+		}
 	} else if (event == nua_i_cancel) {
 		struct sip_call_leg *leg;
 		struct call_leg *other;

-- 
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Gerrit-Project: osmo-sip-connector
Gerrit-Branch: master
Gerrit-Change-Id: I4083ed50d0cf1b302b80354fe0c2b73fc6e14fed
Gerrit-Change-Number: 14994
Gerrit-PatchSet: 1
Gerrit-Owner: keith <keith at rhizomatica.org>
Gerrit-MessageType: newchange
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