/*
 * Here we implement processing of SIP responses to the requests we sent out.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include "../libsip/parse.h"
#include "../libsip/out_msg.h"

#define	MAX_TO_TAG	63

extern char *get_single_header();
extern char *extract_to_tag();

extern struct in_addr sip_bind_ip;
extern unsigned sip_bind_port;
extern char call_id[], from_uri[], to_uri[];

char to_tag[MAX_TO_TAG+1];

add_req_boilerplate(msg, cseq)
	struct sip_msg_out *msg;
	char *cseq;
{
	char strbuf[256];
	int rc;

	sprintf(strbuf, "SIP/2.0/UDP %s:%u",
		inet_ntoa(sip_bind_ip), sip_bind_port);
	rc = out_msg_add_header(msg, "Via", strbuf);
	if (rc < 0)
		return rc;
	rc = out_msg_add_header(msg, "From", from_uri);
	if (rc < 0)
		return rc;
	if (to_tag[0]) {
		sprintf(strbuf, "<%s>;tag=%s", to_uri, to_tag);
		rc = out_msg_add_header(msg, "To", strbuf);
	} else
		rc = out_msg_add_header(msg, "To", to_uri);
	if (rc < 0)
		return rc;
	rc = out_msg_add_header(msg, "Call-ID", call_id);
	if (rc < 0)
		return rc;
	rc = out_msg_add_header(msg, "CSeq", cseq);
	if (rc < 0)
		return rc;
	return out_msg_add_header(msg, "Max-Forwards", "70");
}

add_contact_header(msg)
	struct sip_msg_out *msg;
{
	char strbuf[80];

	sprintf(strbuf, "<sip:%s:%u;transport=udp>",
		inet_ntoa(sip_bind_ip), sip_bind_port);
	return out_msg_add_header(msg, "Contact", strbuf);
}

static void
send_ack(sin)
	struct sockaddr_in *sin;
{
	struct sip_msg_out msg;
	int rc;

	rc = start_request_out_msg(&msg, "ACK", to_uri);
	if (rc < 0) {
msg_size_err:	fprintf(stderr, "composing ACK message: size error\n");
		return;
	}
	rc = add_req_boilerplate(&msg, "1 ACK");
	if (rc < 0)
		goto msg_size_err;
	out_msg_finish(&msg);
	sip_tx_packet(&msg, sin);
}

static void
handle_invite_response(msg, sin)
	struct sip_pkt_rx *msg;
	struct sockaddr_in *sin;
{
	char *tag;

	printf("Response to INVITE: %s\n", msg->status_str);
	tag = extract_to_tag(msg, to_uri);
	if (tag) {
		printf("To tag: %s\n", tag);
		if (strlen(tag) <= MAX_TO_TAG)
			strcpy(to_tag, tag);
		else
			printf("To tag exceeds length limit!\n");
	}
	if (msg->status_code >= 200) {
		printf("Sending ACK\n");
		send_ack(sin);
	}
}

void
process_sip_response(msg, sin)
	struct sip_pkt_rx *msg;
	struct sockaddr_in *sin;
{
	char *call_id_hdr, *cseq_hdr;

	call_id_hdr = get_single_header(msg, "Call-ID", "i", (int *) 0);
	if (!call_id_hdr) {
		printf("Got SIP response w/o Call-ID header\n");
		return;
	}
	if (strcmp(call_id_hdr, call_id)) {
		printf("Got SIP response with wrong Call-ID\n");
		return;
	}
	cseq_hdr = get_single_header(msg, "CSeq", (char *) 0, (int *) 0);
	if (!cseq_hdr) {
		printf("Got SIP response w/o CSeq header\n");
		return;
	}
	if (!strcmp(cseq_hdr, "1 INVITE"))
		handle_invite_response(msg, sin);
	else
		printf("Got SIP resp for our Call-ID with unknown CSeq %s\n",
			cseq_hdr);
}