Fixed send_smpp_message breaking script

It now returns a proper return code, as per the doc

(cherry picked from commit 455066f)

modules/proto_smpp/proto_smpp.c

@@ -471,8 +471,7 @@ static int send_smpp_msg(struct sip_msg *msg, str *name)
 	    parse_sip_msg_uri(msg);
 
 	get_body(msg, &body);
-	send_submit_or_deliver_request(&body, &parse_from_uri(msg)->user,
+	return send_submit_or_deliver_request(&body, &parse_from_uri(msg)->user,
 			&msg->parsed_uri.user, session);
-	return 0;
 }
 

modules/proto_smpp/proto_smpp.h

@@ -69,7 +69,7 @@ struct tcp_connection* smpp_sync_connect(struct socket_info* send_sock,
 void enquire_link(unsigned int ticks, void *param);
 void rpc_bind_sessions(int sender_id, void *param);
 void handle_smpp_msg(char *buffer, smpp_session_t *session, struct receive_info *rcv);
-void send_submit_or_deliver_request(str *msg, str *src, str *dst,
+int send_submit_or_deliver_request(str *msg, str *src, str *dst,
 		smpp_session_t *session);
 smpp_session_t *smpp_session_new(str *name, struct ip_addr *ip, int port,
 		str *system_id, str *password, str *system_type, int src_addr_ton,

modules/proto_smpp/smpp.c

@@ -521,7 +521,7 @@ static int smpp_send_msg(smpp_session_t *smsc, str *buffer)
 	if (ret <= 0) {
 		LM_ERR("cannot fetch connection for %.*s (%d)\n",
 				smsc->name.len, smsc->name.s, ret);
-		return ret;
+		return -1;
 	}
 	/* update connection in case it has changed */
 	smsc->conn_id = conn->id;
@@ -1029,21 +1029,29 @@ void handle_smpp_msg(char *buffer, smpp_session_t *session, struct receive_info
 }
 
 
-void send_submit_or_deliver_request(str *msg, str *src, str *dst,
+int send_submit_or_deliver_request(str *msg, str *src, str *dst,
 		smpp_session_t *session)
 {
 	smpp_submit_sm_req_t *req;
+	int ret;
+
 	LM_DBG("sending submit_sm\n");
 	LM_DBG("FROM: %.*s\n", src->len, src->s);
 	LM_DBG("TO: %.*s\n", dst->len, dst->s);
 	LM_DBG("MESSAGE: %.*s\n", msg->len, msg->s);
 
 	if (build_submit_or_deliver_request(&req, src, dst, msg, session)) {
 		LM_ERR("error creating submit_sm request\n");
-		return;
+		return -1;
 	}
-	smpp_send_msg(session, &req->payload);
+
+	ret = smpp_send_msg(session, &req->payload);
 	pkg_free(req);
+
+	if (ret <=0)
+		return -1;
+
+	return 1;
 }
 
 static void send_enquire_link_request(smpp_session_t *session)