/*
 * 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>
	<support_level>core</support_level>
 ***/

#include "asterisk.h"

#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)
{
	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,
	.requires = "res_pjsip,res_pjsip_session",
);