/*
 * Here we implement our handling of SIP CANCEL method.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <syslog.h>
#include "../include/gsm48_const.h"
#include "../libsip/parse.h"
#include "../libsip/uas_basic.h"
#include "../libsip/out_msg.h"
#include "call.h"

extern struct call *find_call_by_sip_id();

static void
cancel_200_response(req, ess, sin, call)
	struct sip_pkt_rx *req;
	struct uas_parse_hdrs *ess;
	struct sockaddr_in *sin;
	struct call *call;
{
	struct sip_msg_out resp;
	char cseq_str[32];
	int rc;

	start_response_out_msg(&resp, "200 OK");
	rc = out_msg_add_header(&resp, "From", call->invite_from);
	if (rc < 0) {
msg_size_err:	syslog(LOG_ERR, "CANCEL 200 response length exceeded");
		return;
	}
	rc = out_msg_add_header(&resp, "To", call->invite_to);
	if (rc < 0)
		goto msg_size_err;
	rc = out_msg_add_header(&resp, "Call-ID", call->sip_call_id);
	if (rc < 0)
		goto msg_size_err;
	sprintf(cseq_str, "%u CANCEL", call->invite_cseq);
	rc = out_msg_add_header(&resp, "CSeq", cseq_str);
	if (rc < 0)
		goto msg_size_err;
	rc = out_msg_add_header(&resp, "Via", ess->via);
	if (rc < 0)
		goto msg_size_err;
	out_msg_finish(&resp);
	sip_tx_packet(&resp, sin);
}

static void
cancel_481_response(req, ess, sin)
	struct sip_pkt_rx *req;
	struct uas_parse_hdrs *ess;
	struct sockaddr_in *sin;
{
	struct sip_msg_out resp;
	int rc;

	start_response_out_msg(&resp, "481 Call-ID/CSeq not found");
	rc = add_resp_basic_headers(&resp, ess, req->req_method);
	if (rc < 0)
		return;
	out_msg_finish(&resp);
	sip_tx_packet(&resp, sin);
}

void
handle_sip_cancel(req, ess, sin)
	struct sip_pkt_rx *req;
	struct uas_parse_hdrs *ess;
	struct sockaddr_in *sin;
{
	struct call *call;

	call = find_call_by_sip_id(ess->call_id);
	if (!call) {
		cancel_481_response(req, ess, sin);
		return;
	}
	/* weed out wrong CSeq */
	if (ess->cseq_num != call->invite_cseq) {
		cancel_481_response(req, ess, sin);
		return;
	}
	/* it is for us - act on it */
	switch (call->sip_state) {
	case SIP_STATE_INVITE_PROC:
	case SIP_STATE_RINGING:
	case SIP_STATE_RINGING_PRACK:
		call->overall_state = OVERALL_STATE_TEARDOWN;
		disconnect_mncc(call, GSM48_CAUSE_LOC_NET_BEYOND,
				GSM48_CC_CAUSE_NORM_CALL_CLEAR);
		disconnect_tmgw(call);
		strcpy(call->invite_fail, "487 Call attempt terminated");
		signal_invite_error(call);
		break;
	case SIP_STATE_MSG_SIZE_ERR:
		return;
	}
	cancel_200_response(req, ess, sin, call);
}