Add mod_sofia support for setting socket TCP keepalive

Some OSes like linux provide a mechanism for sending TCP keepalive
pings.  Sofia provides its own mechanism for doing this in userspace.
We shouldn't conflate these two mechanisms.

FS-6104

src/mod/endpoints/mod_sofia/mod_sofia.h

@@ -282,6 +282,7 @@ typedef enum {
 	PFLAG_FIRE_MESSAGE_EVENTS,
 	PFLAG_SEND_DISPLAY_UPDATE,
 	PFLAG_RUNNING_TRANS,
+	PFLAG_SOCKET_TCP_KEEPALIVE,
 	PFLAG_TCP_KEEPALIVE,
 	PFLAG_TCP_PINGPONG,
 	PFLAG_TCP_PING2PONG,
@@ -719,6 +720,7 @@ struct sofia_profile {
 	uint32_t rtp_digit_delay;
 	switch_queue_t *event_queue;
 	switch_thread_t *thread;		
+	int socket_tcp_keepalive;
 	int tcp_keepalive;
 	int tcp_pingpong;
 	int tcp_ping2pong;

src/mod/endpoints/mod_sofia/sofia.c

@@ -2478,6 +2478,8 @@ void *SWITCH_THREAD_FUNC sofia_profile_thread_run(switch_thread_t *thread, void
 									 TPTAG_PINGPONG(profile->tcp_ping2pong)),
 							  TAG_IF(sofia_test_pflag(profile, PFLAG_DISABLE_SRV503),
 									 NTATAG_SRV_503(0)),									 
+							  TAG_IF(sofia_test_pflag(profile, PFLAG_SOCKET_TCP_KEEPALIVE),
+									 TPTAG_KEEPALIVE(profile->socket_tcp_keepalive)),
 							  TAG_IF(sofia_test_pflag(profile, PFLAG_TCP_KEEPALIVE),
 									 TPTAG_KEEPALIVE(profile->tcp_keepalive)),									 
 							  NTATAG_DEFAULT_PROXY(profile->outbound_proxy),
@@ -3727,6 +3729,9 @@ switch_status_t config_sofia(sofia_config_t reload, char *profile_name)
 					} else if (!strcasecmp(var, "sip-capture") && switch_true(val)) {
 						sofia_set_flag(profile, TFLAG_CAPTURE);
 						nua_set_params(profile->nua, TPTAG_CAPT(mod_sofia_globals.capture_server), TAG_END());						
+					} else if (!strcasecmp(var, "socket-tcp-keepalive") && !zstr(val)) {
+						profile->socket_tcp_keepalive = atoi(val);
+						sofia_set_pflag(profile, PFLAG_SOCKET_TCP_KEEPALIVE);
 					} else if (!strcasecmp(var, "tcp-keepalive") && !zstr(val)) {
 						profile->tcp_keepalive = atoi(val);
 						sofia_set_pflag(profile, PFLAG_TCP_KEEPALIVE);