/*
 * In this module we implement our RTP handling: obtaining a PSTN-side
 * RTP endpoint from themwi-rtp-mgr, then handling read select on RTP
 * and RTCP UDP sockets.
 */

#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 "../include/tmgw_const.h"
#include "../include/rtp_defs.h"
#include "../include/pstn_defs.h"
#include "../librtpalloc/rtp_alloc_simple.h"

extern const uint16_t pcmu_decode_table[256];
extern const uint16_t pcma_decode_table[256];

struct sockaddr_in rtp_local_addr;
int rtp_udp_fd, rtcp_udp_fd;

static int rtp_start_flag, rtp_bad_flag, rtp_ssrc_chg_flag;
static int rtp_seq_brk_flag, rtp_seq_zero_flag, rtp_seq_neg_flag;
static int rtp_ts_brk_flag;
static uint32_t rtp_ssrc;
static uint32_t rtp_last_ts;
static uint16_t rtp_last_seq;
static int got_some_rtcp;

void
obtain_rtp_endp()
{
	int rc;
	struct rtp_alloc_simple res;

	rc = rtp_alloc_simple(TMGW_EP_TYPE_PSTN_ONLY, &res);
	if (rc < 0)
		exit(1);	/* error msg already printed */
	bcopy(&res.pstn_addr, &rtp_local_addr, sizeof(struct sockaddr_in));
	rtp_udp_fd = res.pstn_rtp_fd;
	rtcp_udp_fd = res.pstn_rtcp_fd;
}

void
rtp_rx_select()
{
	struct rtp_packet pkt;
	struct sockaddr_in sin_from;
	socklen_t addrlen;
	int16_t seq_delta;
	int32_t ts_delta;
	const uint16_t *pcm_dec_table;
	int16_t pcm_samples[FRAME_20MS];
	unsigned n;
	int rc;

	addrlen = sizeof(struct sockaddr_in);
	rc = recvfrom(rtp_udp_fd, &pkt, sizeof pkt, 0,
			(struct sockaddr *) &sin_from, &addrlen);
	if (rc < 0)
		return;
	if (rc != RTP_PACKET_SIZE_PSTN) {
bad_rtp_pkt:	if (!rtp_bad_flag) {
			printf("Got a bad RTP packet\n");
			rtp_bad_flag = 1;
		}
		return;
	}
	if (pkt.v_p_x_cc != 0x80)
		goto bad_rtp_pkt;
	switch (pkt.m_pt & 0x7F) {
	case PSTN_CODEC_PCMU:
		pcm_dec_table = pcmu_decode_table;
		break;
	case PSTN_CODEC_PCMA:
		pcm_dec_table = pcma_decode_table;
		break;
	default:
		goto bad_rtp_pkt;
	}
	if (rtp_start_flag && pkt.ssrc != rtp_ssrc) {
		if (!rtp_ssrc_chg_flag) {
			printf("Rx RTP stream changed SSRC\n");
			rtp_ssrc_chg_flag = 1;
		}
	} else if (rtp_start_flag) {
		seq_delta = ntohs(pkt.seq) - rtp_last_seq;
		ts_delta = ntohl(pkt.tstamp) - rtp_last_ts;
		if (seq_delta == 0) {
			if (!rtp_seq_zero_flag) {
				printf("Rx RTP seq zero increment\n");
				rtp_seq_zero_flag = 1;
			}
			return;
		}
		if (seq_delta < 0) {
			if (!rtp_seq_neg_flag) {
				printf("Rx RTP seq negative increment\n");
				rtp_seq_neg_flag = 1;
			}
			return;
		}
		if (seq_delta != 1) {
			if (!rtp_seq_brk_flag) {
				printf("Rx RTP stream seq break\n");
				rtp_seq_brk_flag = 1;
			}
		} else if (ts_delta != 160) {
			if (!rtp_ts_brk_flag) {
				printf("Rx RTP stream tstamp break\n");
				rtp_ts_brk_flag = 1;
			}
		}
	}
	rtp_ssrc = pkt.ssrc;
	rtp_last_ts = ntohl(pkt.tstamp);
	rtp_last_seq = ntohs(pkt.seq);
	if (!rtp_start_flag) {
		printf("Rx RTP stream begins with seq=%u ts=%u\n",
			rtp_last_seq, rtp_last_ts);
		rtp_start_flag = 1;
	}
	for (n = 0; n < FRAME_20MS; n++)
		pcm_samples[n] = pcm_dec_table[pkt.payload[n]];
	process_rx_frame(pcm_samples);
}

void
rtcp_rx_select()
{
	u_char buf[512];

	recv(rtcp_udp_fd, buf, sizeof buf, 0);
	if (!got_some_rtcp) {
		printf("Got some RTCP\n");
		got_some_rtcp = 1;
	}
}