Osmocom library for network/soecket abstraction and osmux audio multiplex https://osmocom.org/projects/libosmo-netif
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
libosmo-netif/src/osmux.c

182 lines
5.0 KiB

/*
* (C) 2012-2017 by Pablo Neira Ayuso <pablo@gnumonks.org>
* (C) 2012 by On Waves ehf <http://www.on-waves.com>
* (C) 2015-2022 by sysmocom - s.f.m.c. GmbH
*
* SPDX-License-Identifier: GPL-2.0+
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <stdio.h>
#include <string.h>
#include <osmocom/core/msgb.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/timer_compat.h>
#include <osmocom/core/select.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/logging.h>
#include <osmocom/netif/amr.h>
#include <osmocom/netif/rtp.h>
#include <osmocom/netif/osmux.h>
#include <arpa/inet.h>
/*! \addtogroup osmux Osmocom Multiplex Protocol
* @{
*
* This code implements a variety of utility functions related to the
* OSMUX user-plane multiplexing protocol, an efficient alternative to
* plain UDP/RTP streams for voice transport in back-haul of cellular
* networks.
*
* For information about the OSMUX protocol design, please see the
* OSMUX reference manual at
* http://ftp.osmocom.org/docs/latest/osmux-reference.pdf
*/
/*! \file osmux.c
* \brief Osmocom multiplex protocol helpers
*/
static uint32_t osmux_get_payload_len(struct osmux_hdr *osmuxh)
{
return osmo_amr_bytes(osmuxh->amr_ft) * (osmuxh->ctr+1);
}
#define SNPRINTF_BUFFER_SIZE(ret, remain, offset) \
if (ret < 0) \
ret = 0; \
offset += ret; \
if (ret > remain) \
ret = remain; \
remain -= ret;
static int osmux_snprintf_header(char *buf, size_t size, struct osmux_hdr *osmuxh)
{
unsigned int remain = size, offset = 0;
int ret;
ret = snprintf(buf, remain, "OSMUX seq=%03u ccid=%03u "
"ft=%01u rtp_m=%01u ctr=%01u "
"amr_f=%01u amr_q=%01u "
"amr_ft=%02u amr_cmr=%02u",
osmuxh->seq, osmuxh->circuit_id,
osmuxh->ft, osmuxh->rtp_m, osmuxh->ctr,
osmuxh->amr_f, osmuxh->amr_q,
osmuxh->amr_ft, osmuxh->amr_cmr);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
return offset;
}
static int osmux_snprintf_payload(char *buf, size_t size,
const uint8_t *payload, int payload_len)
{
unsigned int remain = size, offset = 0;
int ret, i;
ret = snprintf(buf + offset, remain, "[ ");
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
for (i=0; i<payload_len; i++) {
ret = snprintf(buf + offset, remain, "%02x ", payload[i]);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
}
ret = snprintf(buf + offset, remain, "]");
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
return offset;
}
/*! Print osmux header fields and payload from msg into buffer buf.
* \param[out] buf buffer to store the output into
* \param[in] len length of buf in bytes
* \param[in] msgb message buffer containing one or more osmux frames
* \returns the number of characters printed (excluding the null byte used to end output to strings).
*
* If the output was truncated due to this limit, then the return value is the number of characters
* (excluding the terminating null byte) which would have been written to the final string if enough
* space had been available.
*/
int osmux_snprintf(char *buf, size_t size, struct msgb *msg)
{
unsigned int remain = size;
unsigned int msg_off = 0;
struct osmux_hdr *osmuxh;
unsigned int offset = 0;
int msg_len = msg->len;
uint32_t payload_len;
int ret;
if (size)
buf[0] = '\0';
while (msg_len > 0) {
if (msg_len < sizeof(struct osmux_hdr)) {
LOGP(DLMUX, LOGL_ERROR,
"No room for OSMUX header: only %d bytes\n",
msg_len);
return -1;
}
osmuxh = (struct osmux_hdr *)((uint8_t *)msg->data + msg_off);
if (msg_off) {
ret = snprintf(buf + offset, remain, ", ");
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
}
ret = osmux_snprintf_header(buf + offset, remain, osmuxh);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
msg_off += sizeof(struct osmux_hdr);
msg_len -= sizeof(struct osmux_hdr);
switch (osmuxh->ft) {
case OSMUX_FT_SIGNAL:
ret = snprintf(buf + offset, remain, "[signal]");
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
return -1;
case OSMUX_FT_DUMMY:
case OSMUX_FT_VOICE_AMR:
if (!osmo_amr_ft_valid(osmuxh->amr_ft)) {
LOGP(DLMUX, LOGL_ERROR, "Bad AMR FT %d, skipping\n",
osmuxh->amr_ft);
return -1;
}
payload_len = osmux_get_payload_len(osmuxh);
if (msg_len < payload_len) {
LOGP(DLMUX, LOGL_ERROR,
"No room for OSMUX payload: only %d bytes\n",
msg_len);
return -1;
}
if (osmuxh->ft == OSMUX_FT_VOICE_AMR) {
ret = snprintf(buf + offset, remain, " ");
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
ret = osmux_snprintf_payload(buf + offset, remain,
osmux_get_payload(osmuxh),
payload_len);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
}
msg_off += payload_len;
msg_len -= payload_len;
break;
default:
LOGP(DLMUX, LOGL_ERROR, "Unknown OSMUX ft value %d\n",
osmuxh->ft);
return -1;
}
}
return offset;
}
/*! @} */