add generic keepalive system and implement it in sofia to send MESSAGE or INFO packets in-dialog at specified interval.

Adds app: enable_keepalive 0|<seconds>
This app can be run in the dialplan or with execute_on_* type variables for B-legs.

Adds sofia param: keepalive-method  : defaults to MESSAGE can also be "INFO"
This param sets which SIP method to use.

src/mod/endpoints/mod_sofia/mod_sofia.c

@@ -1124,6 +1124,38 @@ static switch_status_t sofia_receive_message(switch_core_session_t *session, swi
 
 	/* ones that do not need to lock sofia mutex */
 	switch (msg->message_id) {
+	case SWITCH_MESSAGE_INDICATE_KEEPALIVE:
+		{
+			if (msg->numeric_arg) {
+				sofia_set_flag_locked(tech_pvt, TFLAG_KEEPALIVE);
+			} else {
+				sofia_clear_flag_locked(tech_pvt, TFLAG_KEEPALIVE);
+			}
+		}
+		break;
+	case SWITCH_MESSAGE_HEARTBEAT_EVENT:
+		{
+			char pl[160] = "";
+
+			switch_snprintf(pl, sizeof(pl), "KEEP-ALIVE %d\n", ++tech_pvt->keepalive);
+
+			if (sofia_test_flag(tech_pvt, TFLAG_KEEPALIVE)) {
+				if (tech_pvt->profile->keepalive == KA_MESSAGE) {
+					nua_message(tech_pvt->nh,
+								SIPTAG_CONTENT_TYPE_STR("text/plain"),
+								TAG_IF(!zstr(tech_pvt->user_via), SIPTAG_VIA_STR(tech_pvt->user_via)),
+								SIPTAG_PAYLOAD_STR(pl),
+								TAG_END());
+				} else if (tech_pvt->profile->keepalive == KA_INFO) {
+					nua_info(tech_pvt->nh,
+							 SIPTAG_CONTENT_TYPE_STR("text/plain"),
+							 TAG_IF(!zstr(tech_pvt->user_via), SIPTAG_VIA_STR(tech_pvt->user_via)),
+							 SIPTAG_PAYLOAD_STR(pl),
+							 TAG_END());
+				}
+			}
+		}
+		break;
 	case SWITCH_MESSAGE_INDICATE_RECOVERY_REFRESH:
 	case SWITCH_MESSAGE_INDICATE_APPLICATION_EXEC:
 		break;

src/mod/endpoints/mod_sofia/mod_sofia.h

@@ -322,6 +322,7 @@ typedef enum {
 	TFLAG_CAPTURE,
 	TFLAG_REINVITED,
 	TFLAG_PASS_ACK,
+	TFLAG_KEEPALIVE,
 	/* No new flags below this line */
 	TFLAG_MAX
 } TFLAGS;
@@ -534,6 +535,11 @@ typedef enum {
 
 #define MAX_RTPIP 50
 
+typedef enum {
+	KA_MESSAGE,
+	KA_INFO
+} ka_type_t;
+
 struct sofia_profile {
 	int debug;
 	int parse_invite_tel_params;
@@ -706,6 +712,7 @@ struct sofia_profile {
 	int tcp_keepalive;
 	int tcp_pingpong;
 	int tcp_ping2pong;
+	ka_type_t keepalive;
 };
 
 
@@ -772,6 +779,7 @@ struct private_object {
 	int respond_code;
 	char *respond_dest;
 	time_t last_vid_info;
+	uint32_t keepalive;
 };
 
 

src/mod/endpoints/mod_sofia/sofia.c

@@ -4025,6 +4025,14 @@ switch_status_t config_sofia(sofia_config_t reload, char *profile_name)
 						profile->debug = atoi(val);
 					} else if (!strcasecmp(var, "parse-invite-tel-params")) {
 						profile->parse_invite_tel_params = switch_true(val);
+					} else if (!strcasecmp(var, "keepalive-method")) {
+						if (!zstr(val)) {
+							if (!strcasecmp(val, "info")) {
+								profile->keepalive = KA_INFO;
+							} else {
+								profile->keepalive = KA_MESSAGE;								
+							}
+						}
 					} else if (!strcasecmp(var, "shutdown-on-fail")) {
 						profile->shutdown_type = switch_core_strdup(profile->pool, val);
 					} else if (!strcasecmp(var, "sip-trace") && switch_true(val)) {