res_pjsip_empty_info: Respond to empty SIP INFO packets

Some SBCs require responses to empty SIP INFO packets
after establishing call via INVITE, if not responded to
they may drop your call after unspecified timeout of X minutes.

They are identified by having no Content-Type, check for this
and respond with 200 - OK message.

ASTERISK-24986 #close
Reported-by: Ilya Trikoz, Federico Santulli

Change-Id: Ib27e4f07151e5aef28fa587e4ead36c5b87c43e0

CHANGES

@@ -252,6 +252,12 @@ res_pjsip
    will be used instead. The new SIP resolver provides NAPTR support, improved
    SRV support, and AAAA record support.
 
+res_pjsip_info_empty
+--------------------
+ * A new module that can respond to empty Content-Type INFO packets during call.
+   Some SBCs will terminate a call if their empty INFO packets are not responded
+   to within a predefined time.
+
 res_pjsip_outbound_registration
 -------------------------------
 * A new 'fatal_retry_interval' option has been added to outbound registration.
@@ -264,6 +270,7 @@ res_pjsip_outbound_publish
  * Added a new multi_user option that when set to 'yes' allows a given configuration
    to be used for multiple users.
 
+
 CEL Backends
 ------------------
 

res/res_pjsip_dtmf_info.c

@@ -103,13 +103,13 @@ static int dtmf_info_incoming_request(struct ast_sip_session *session, struct pj
 	if (!body || !body->len) {
 		/* need to return 200 OK on empty body */
 		send_response(session, rdata, 200);
-		return 0;
+		return 1;
 	}
 
 	res = body->print_body(body, buf, body->len);
 	if (res < 0) {
 		send_response(session, rdata, 500);
-		return 0;
+		return 1;
 	}
 	buf[res] = '\0';
 
@@ -150,11 +150,12 @@ static int dtmf_info_incoming_request(struct ast_sip_session *session, struct pj
 	}
 
 	send_response(session, rdata, event ? 200 : 500);
-	return event ? 0 : -1;
+	return 1;
 }
 
 static struct ast_sip_session_supplement dtmf_info_supplement = {
 	.method = "INFO",
+	.priority = AST_SIP_SUPPLEMENT_PRIORITY_FIRST,
 	.incoming_request = dtmf_info_incoming_request,
 };
 

res/res_pjsip_empty_info.c

@@ -0,0 +1,89 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2016, Digium, Inc.
+ *
+ * Bradley Latus <brad.latus@gmail.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*** MODULEINFO
+	<depend>pjproject</depend>
+	<depend>res_pjsip</depend>
+	<depend>res_pjsip_session</depend>
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_REGISTER_FILE()
+
+#include <pjsip.h>
+#include <pjsip_ua.h>
+
+#include "asterisk/res_pjsip.h"
+#include "asterisk/res_pjsip_session.h"
+#include "asterisk/module.h"
+
+static void send_response(struct ast_sip_session *session,
+		struct pjsip_rx_data *rdata, int code)
+{
+	pjsip_tx_data *tdata;
+	pjsip_dialog *dlg = session->inv_session->dlg;
+
+	if (pjsip_dlg_create_response(dlg, rdata, code, NULL, &tdata) == PJ_SUCCESS) {
+		struct pjsip_transaction *tsx = pjsip_rdata_get_tsx(rdata);
+		pjsip_dlg_send_response(dlg, tsx, tdata);
+	}
+}
+
+static int empty_info_incoming_request(struct ast_sip_session *session,
+		struct pjsip_rx_data *rdata)
+{
+	if (!rdata->msg_info.ctype) {
+		/* Need to return 200 OK on empty body */
+		/* Some SBCs use empty INFO as a KEEPALIVE */
+		send_response(session, rdata, 200);
+		return 1;
+	}
+
+	/* Let another module respond */
+	return 0;
+
+}
+
+static struct ast_sip_session_supplement empty_info_supplement = {
+	.method = "INFO",
+	.priority = AST_SIP_SUPPLEMENT_PRIORITY_LAST,
+	.incoming_request = empty_info_incoming_request,
+};
+
+static int load_module(void)
+{
+	CHECK_PJSIP_SESSION_MODULE_LOADED();
+
+	ast_sip_session_register_supplement(&empty_info_supplement);
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+static int unload_module(void)
+{
+	ast_sip_session_unregister_supplement(&empty_info_supplement);
+	return 0;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP Empty INFO Support",
+	.support_level = AST_MODULE_SUPPORT_CORE,
+	.load = load_module,
+	.unload = unload_module,
+	.load_pri = AST_MODPRI_APP_DEPEND,
+);

res/res_pjsip_one_touch_record_info.c

@@ -72,13 +72,13 @@ static int handle_incoming_request(struct ast_sip_session *session, struct pjsip
 
 	if (!session->channel) {
 		send_response(session, 481, rdata);
-		return 0;
+		return 1;
 	}
 
 	/* Is this endpoint configured with One Touch Recording? */
 	if (!session->endpoint->info.recording.enabled || ast_strlen_zero(feature)) {
 		send_response(session, 403, rdata);
-		return 0;
+		return 1;
 	}
 
 	ast_channel_lock(session->channel);
@@ -87,7 +87,7 @@ static int handle_incoming_request(struct ast_sip_session *session, struct pjsip
 
 	if (feature_res || ast_strlen_zero(feature_code)) {
 		send_response(session, 403, rdata);
-		return 0;
+		return 1;
 	}
 
 	for (digit = feature_code; *digit; ++digit) {
@@ -97,11 +97,12 @@ static int handle_incoming_request(struct ast_sip_session *session, struct pjsip
 
 	send_response(session, 200, rdata);
 
-	return 0;
+	return 1;
 }
 
 static struct ast_sip_session_supplement info_supplement = {
 	.method = "INFO",
+	.priority = AST_SIP_SUPPLEMENT_PRIORITY_FIRST,
 	.incoming_request = handle_incoming_request,
 };