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libosmo-netif
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osmux: Split input and output code into separate files 

The output and input paths are totally independent, they share no code
or structures holding state. They can be operated totally independently.
Hence, let's split the code into separate file since when someone looks
at the osmux code one is really looking specifically at Tx or Rx side,
but not at both sides.
Moreover, the "input" and "output" concepts have always been a bit
difficult to understand (would have been better calling them "src" and
"sink" instead), which adds more confusion when trying to find the
relevant part of code.

Change-Id: Ia72995092a36ca50147611e617cb88c4dcf231d5
This commit is contained in:
Pau Espin 2022-09-29 12:55:56 +02:00
parent b0369f375f
commit 5fd33980b8
4 changed files with 1065 additions and 959 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/Makefile.am
View File

@ -17,6 +17,8 @@ libosmonetif_la_SOURCES = amr.c \
ipa_unit.c \
jibuf.c \
osmux.c \
osmux_input.c \
osmux_output.c \
prim.c \
rs232.c \
rtp.c \

960
src/osmux.c
View File

@ -1,7 +1,7 @@
/*
* (C) 2012-2017 by Pablo Neira Ayuso <pablo@gnumonks.org>
* (C) 2012 by On Waves ehf <http://www.on-waves.com>
* (C) 2015-2017 by sysmocom - s.f.m.c. GmbH
* (C) 2015-2022 by sysmocom - s.f.m.c. GmbH
*
* SPDX-License-Identifier: GPL-2.0+
*
@ -44,969 +44,11 @@
* \brief Osmocom multiplex protocol helpers
*/
/* This allows you to debug osmux message transformations (spamming) */
#if 0
#define DEBUG_MSG 0
#endif
/* delta time between two RTP messages (in microseconds) */
#define DELTA_RTP_MSG 20000
/* delta time between two RTP messages (in samples, 8kHz) */
#define DELTA_RTP_TIMESTAMP 160
static void *osmux_ctx;
static uint32_t osmux_get_payload_len(struct osmux_hdr *osmuxh)
{
return osmo_amr_bytes(osmuxh->amr_ft) * (osmuxh->ctr+1);
}
static uint32_t osmux_ft_dummy_size(uint8_t amr_ft, uint8_t batch_factor)
{
return sizeof(struct osmux_hdr) + (osmo_amr_bytes(amr_ft) * batch_factor);
}
struct osmux_hdr *osmux_xfrm_output_pull(struct msgb *msg)
{
struct osmux_hdr *osmuxh;
next:
osmuxh = NULL;
if (msg->len > sizeof(struct osmux_hdr)) {
size_t len;
osmuxh = (struct osmux_hdr *)msg->data;
switch (osmuxh->ft) {
case OSMUX_FT_VOICE_AMR:
break;
case OSMUX_FT_DUMMY:
len = osmux_ft_dummy_size(osmuxh->amr_ft, osmuxh->ctr + 1);
if (msgb_length(msg) < len) {
LOGP(DLMUX, LOGL_ERROR, "Discarding bad Dummy FT: %s\n",
osmo_hexdump(msg->data, msgb_length(msg)));
return NULL;
}
msgb_pull(msg, len);
goto next;
default:
LOGP(DLMUX, LOGL_ERROR, "Discarding unsupported Osmux FT %d\n",
osmuxh->ft);
return NULL;
}
if (!osmo_amr_ft_valid(osmuxh->amr_ft)) {
LOGP(DLMUX, LOGL_ERROR, "Discarding bad AMR FT %d\n",
osmuxh->amr_ft);
return NULL;
}
len = osmo_amr_bytes(osmuxh->amr_ft) * (osmuxh->ctr+1) +
sizeof(struct osmux_hdr);
if (msgb_length(msg) < len) {
LOGP(DLMUX, LOGL_ERROR,
"Discarding malformed OSMUX message: %s\n",
osmo_hexdump(msg->data, msgb_length(msg)));
return NULL;
}
msgb_pull(msg, len);
} else if (msg->len > 0) {
LOGP(DLMUX, LOGL_ERROR,
"remaining %d bytes, broken osmuxhdr?\n", msg->len);
}
return osmuxh;
}
static struct msgb *
osmux_rebuild_rtp(struct osmux_out_handle *h, struct osmux_hdr *osmuxh,
void *payload, int payload_len, bool first_pkt)
{
struct msgb *prev_msg, *out_msg;
struct timespec *prev_ts, *out_ts;
struct rtp_hdr *rtph;
struct amr_hdr *amrh;
struct timespec delta = { .tv_sec = 0, .tv_nsec = DELTA_RTP_MSG*1000 };
unsigned int msg_len = sizeof(struct rtp_hdr) +
sizeof(struct amr_hdr) +
payload_len;
if (h->rtp_msgb_alloc_cb) {
out_msg = h->rtp_msgb_alloc_cb(h->rtp_msgb_alloc_cb_data, msg_len);
} else {
out_msg = msgb_alloc(msg_len, "osmux-rtp");
}
if (out_msg == NULL)
return NULL;
/* Reconstruct RTP header */
rtph = (struct rtp_hdr *)out_msg->data;
rtph->csrc_count = 0;
rtph->extension = 0;
rtph->version = RTP_VERSION;
rtph->payload_type = h->rtp_payload_type;
/* ... emulate timestamp and ssrc */
rtph->timestamp = htonl(h->rtp_timestamp);
rtph->sequence = htons(h->rtp_seq);
rtph->ssrc = htonl(h->rtp_ssrc);
/* rtp packet with the marker bit is always guaranteed to be the first
* one. We want to notify with marker in 2 scenarios:
* 1- Sender told us through osmux frame rtp_m.
* 2- Intermediate osmux frame lost (seq gap), otherwise rtp receiver only sees
* steady increase of delay
*/
rtph->marker = first_pkt &&
(osmuxh->rtp_m || (osmuxh->seq != ((h->osmux_seq_ack + 1) & 0xff)));
msgb_put(out_msg, sizeof(struct rtp_hdr));
/* Reconstruct AMR header */
amrh = (struct amr_hdr *)out_msg->tail;
amrh->cmr = osmuxh->amr_cmr;
amrh->f = osmuxh->amr_f;
amrh->ft = osmuxh->amr_ft;
amrh->q = osmuxh->amr_q;
msgb_put(out_msg, sizeof(struct amr_hdr));
/* add AMR speech data */
memcpy(out_msg->tail, payload, payload_len);
msgb_put(out_msg, payload_len);
/* bump last RTP sequence number and timestamp that has been used */
h->rtp_seq++;
h->rtp_timestamp += DELTA_RTP_TIMESTAMP;
out_ts = ((struct timespec *)&((out_msg)->cb[0]));
if (first_pkt || llist_empty(&h->list)) {
osmo_clock_gettime(CLOCK_MONOTONIC, out_ts);
} else {
prev_msg = llist_last_entry(&h->list, struct msgb, list);
prev_ts = ((struct timespec *)&((prev_msg)->cb[0]));
timespecadd(prev_ts, &delta, out_ts);
}
return out_msg;
}
static void osmux_xfrm_output_trigger(void *data)
{
struct osmux_out_handle *h = data;
struct timespec delay_ts, now;
struct msgb *msg, *next;
llist_for_each_entry_safe(msg, next, &h->list, list) {
osmo_clock_gettime(CLOCK_MONOTONIC, &now);
struct timespec *msg_ts = ((struct timespec *)&((msg)->cb[0]));
if (timespeccmp(msg_ts, &now, >)) {
timespecsub(msg_ts, &now, &delay_ts);
osmo_timer_schedule(&h->timer,
delay_ts.tv_sec, delay_ts.tv_nsec / 1000);
return;
}
/* Transmit the rtp packet */
llist_del(&msg->list);
if (h->tx_cb)
h->tx_cb(msg, h->data);
else
msgb_free(msg);
}
}
/*! \brief Generate RTP packets from osmux frame AMR payload set and schedule
* them for transmission at appropiate time.
* \param[in] h the osmux out handle handling a specific CID
* \param[in] osmuxh Buffer pointing to osmux frame header structure and AMR payload
* \return Number of generated RTP packets
*
* The osmux frame passed to this function must be of the type OSMUX_FT_VOICE_AMR.
* The generated RTP packets are kept into h's internal list and sent to the
* callback configured through osmux_xfrm_output_set_tx_cb when are ready to be
* transmitted according to schedule.
*/
int osmux_xfrm_output_sched(struct osmux_out_handle *h, struct osmux_hdr *osmuxh)
{
struct timespec now, *msg_ts;
struct msgb *msg;
int i;
bool was_empty = llist_empty(&h->list);
if (!was_empty) {
/* If we received new data it means we are behind schedule and
* we should flush all previous quickly */
osmo_clock_gettime(CLOCK_MONOTONIC, &now);
llist_for_each_entry(msg, &h->list, list) {
msg_ts = ((struct timespec *)&((msg)->cb[0]));
*msg_ts = now;
}
osmo_timer_schedule(&h->timer, 0, 0);
}
for (i = 0; i < osmuxh->ctr + 1; i++) {
struct rtp_hdr *rtph;
msg = osmux_rebuild_rtp(h, osmuxh,
osmux_get_payload(osmuxh) +
i * osmo_amr_bytes(osmuxh->amr_ft),
osmo_amr_bytes(osmuxh->amr_ft), !i);
if (msg == NULL)
continue;
rtph = osmo_rtp_get_hdr(msg);
if (rtph == NULL)
continue;
llist_add_tail(&msg->list, &h->list);
}
/* Update last seen seq number: */
h->osmux_seq_ack = osmuxh->seq;
/* In case list is still empty after parsing messages, no need to rearm */
if(was_empty && !llist_empty(&h->list))
osmux_xfrm_output_trigger(h);
return i;
}
/*! \brief Flush all scheduled RTP packets still pending to be transmitted
* \param[in] h the osmux out handle to flush
*
* This function will immediately call the transmit callback for all queued RTP
* packets, making sure the list ends up empty. It will also stop all internal
* timers to make sure the osmux_out_handle can be dropped or re-used by calling
* osmux_xfrm_output on it.
*/
void osmux_xfrm_output_flush(struct osmux_out_handle *h)
{
struct msgb *msg, *next;
if (osmo_timer_pending(&h->timer))
osmo_timer_del(&h->timer);
llist_for_each_entry_safe(msg, next, &h->list, list) {
llist_del(&msg->list);
if (h->tx_cb)
h->tx_cb(msg, h->data);
else
msgb_free(msg);
}
}
struct osmux_batch {
struct osmo_timer_list timer;
struct osmux_hdr *osmuxh;
struct llist_head circuit_list;
unsigned int remaining_bytes;
uint32_t nmsgs;
int ndummy;
};
struct osmux_circuit {
struct llist_head head;
int ccid;
struct llist_head msg_list;
int nmsgs;
int dummy;
uint8_t seq;
};
/* returns: 1 if batch is full, 0 if batch still not full, negative on error. */
static int osmux_batch_enqueue(struct msgb *msg, struct osmux_circuit *circuit,
uint8_t batch_factor)
{
/* Validate amount of messages per batch. The counter field of the
* osmux header is just 3 bits long, so make sure it doesn't overflow.
*/
OSMO_ASSERT(batch_factor <= 8);
if (circuit->nmsgs >= batch_factor) {
struct rtp_hdr *rtph;
rtph = osmo_rtp_get_hdr(msg);
if (rtph == NULL)
return -1;
LOGP(DLMUX, LOGL_DEBUG, "Batch is full for RTP sssrc=%u\n", rtph->ssrc);
return 1;
}
llist_add_tail(&msg->list, &circuit->msg_list);
circuit->nmsgs++;
return 0;
}
static void osmux_batch_dequeue(struct msgb *msg, struct osmux_circuit *circuit)
{
llist_del(&msg->list);
circuit->nmsgs--;
}
static void osmux_circuit_del_msgs(struct osmux_batch *batch, struct osmux_circuit *circuit)
{
struct msgb *cur, *tmp;
llist_for_each_entry_safe(cur, tmp, &circuit->msg_list, list) {
osmux_batch_dequeue(cur, circuit);
msgb_free(cur);
batch->nmsgs--;
}
}
struct osmux_input_state {
struct msgb *out_msg;
struct msgb *msg;
struct rtp_hdr *rtph;
struct amr_hdr *amrh;
uint32_t amr_payload_len;
struct osmux_circuit *circuit;
int add_osmux_hdr;
};
static int osmux_batch_put(struct osmux_batch *batch,
struct osmux_input_state *state)
{
if (state->add_osmux_hdr) {
struct osmux_hdr *osmuxh;
osmuxh = (struct osmux_hdr *)msgb_put(state->out_msg,
sizeof(struct osmux_hdr));
osmuxh->ft = OSMUX_FT_VOICE_AMR;
osmuxh->ctr = 0;
osmuxh->rtp_m = osmuxh->rtp_m || state->rtph->marker;
osmuxh->seq = state->circuit->seq++;
osmuxh->circuit_id = state->circuit->ccid;
osmuxh->amr_ft = state->amrh->ft;
/* annotate current osmux header */
batch->osmuxh = osmuxh;
} else {
if (batch->osmuxh->ctr == 0x7) {
LOGP(DLMUX, LOGL_ERROR, "cannot add msg=%p, "
"too many messages for this RTP ssrc=%u\n",
state->msg, state->rtph->ssrc);
return 0;
}
batch->osmuxh->ctr++;
}
/* For fields below, we only use the last included in batch and ignore any previous: */
batch->osmuxh->amr_cmr = state->amrh->cmr;
batch->osmuxh->amr_f = state->amrh->f;
batch->osmuxh->amr_q = state->amrh->q;
memcpy(state->out_msg->tail, osmo_amr_get_payload(state->amrh),
state->amr_payload_len);
msgb_put(state->out_msg, state->amr_payload_len);
return 0;
}
static void osmux_encode_dummy(struct osmux_batch *batch, uint8_t batch_factor,
struct osmux_input_state *state)
{
struct osmux_hdr *osmuxh;
/* TODO: This should be configurable at some point. */
uint32_t payload_size = osmux_ft_dummy_size(AMR_FT_3, batch_factor) -
sizeof(struct osmux_hdr);
osmuxh = (struct osmux_hdr *)state->out_msg->tail;
osmuxh->ft = OSMUX_FT_DUMMY;
osmuxh->ctr = batch_factor - 1;
osmuxh->amr_f = 0;
osmuxh->amr_q= 0;
osmuxh->seq = 0;
osmuxh->circuit_id = state->circuit->ccid;
osmuxh->amr_cmr = 0;
osmuxh->amr_ft = AMR_FT_3;
msgb_put(state->out_msg, sizeof(struct osmux_hdr));
memset(state->out_msg->tail, 0xff, payload_size);
msgb_put(state->out_msg, payload_size);
}
static struct msgb *osmux_build_batch(struct osmux_batch *batch,
uint32_t batch_size, uint8_t batch_factor)
{
struct msgb *batch_msg;
struct osmux_circuit *circuit;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "Now building batch\n");
#endif
batch_msg = msgb_alloc(batch_size, "osmux");
if (batch_msg == NULL) {
LOGP(DLMUX, LOGL_ERROR, "Not enough memory\n");
return NULL;
}
llist_for_each_entry(circuit, &batch->circuit_list, head) {
struct msgb *cur, *tmp;
int ctr = 0;
int prev_amr_ft;
if (circuit->dummy) {
struct osmux_input_state state = {
.out_msg = batch_msg,
.circuit = circuit,
};
osmux_encode_dummy(batch, batch_factor, &state);
continue;
}
llist_for_each_entry_safe(cur, tmp, &circuit->msg_list, list) {
struct osmux_input_state state = {
.msg = cur,
.out_msg = batch_msg,
.circuit = circuit,
};
uint32_t amr_len;
#ifdef DEBUG_MSG
char buf[4096];
osmo_rtp_snprintf(buf, sizeof(buf), cur);
buf[sizeof(buf)-1] = '\0';
LOGP(DLMUX, LOGL_DEBUG, "to BSC-NAT: %s\n", buf);
#endif
state.rtph = osmo_rtp_get_hdr(cur);
if (!state.rtph)
return NULL;
state.amrh = osmo_rtp_get_payload(state.rtph, state.msg, &amr_len);
if (!state.amrh)
return NULL;
state.amr_payload_len = amr_len - sizeof(struct amr_hdr);
if (ctr == 0) {
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "Add osmux header (First in batch)\n");
#endif
state.add_osmux_hdr = 1;
} else if (prev_amr_ft != state.amrh->ft) {
/* If AMR FT changed, we have to generate an extra batch osmux header: */
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "Add osmux header (New AMR FT)\n");
#endif
state.add_osmux_hdr = 1;
}
osmux_batch_put(batch, &state);
osmux_batch_dequeue(cur, circuit);
prev_amr_ft = state.amrh->ft;
ctr++;
msgb_free(cur);
batch->nmsgs--;
}
}
return batch_msg;
}
void osmux_xfrm_input_deliver(struct osmux_in_handle *h)
{
struct msgb *batch_msg;
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "invoking delivery function\n");
#endif
batch_msg = osmux_build_batch(batch, h->batch_size, h->batch_factor);
if (!batch_msg)
return;
h->stats.output_osmux_msgs++;
h->stats.output_osmux_bytes += batch_msg->len;
h->deliver(batch_msg, h->data);
osmo_timer_del(&batch->timer);
batch->remaining_bytes = h->batch_size;
if (batch->ndummy) {
osmo_timer_schedule(&batch->timer, 0,
h->batch_factor * DELTA_RTP_MSG);
}
}
static void osmux_batch_timer_expired(void *data)
{
struct osmux_in_handle *h = data;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "osmux_batch_timer_expired\n");
#endif
osmux_xfrm_input_deliver(h);
}
static int osmux_rtp_amr_payload_len(struct amr_hdr *amrh, uint32_t amr_len)
{
int amr_payload_len;
if (!osmo_amr_ft_valid(amrh->ft))
return -1;
amr_payload_len = amr_len - sizeof(struct amr_hdr);
/* The AMR payload does not fit with what we expect */
if (osmo_amr_bytes(amrh->ft) != amr_payload_len) {
LOGP(DLMUX, LOGL_ERROR,
"Bad AMR frame, expected %zd bytes, got %d bytes\n",
osmo_amr_bytes(amrh->ft), amr_len);
return -1;
}
return amr_payload_len;
}
/* Last stored AMR FT to be added in the current osmux batch. -1 if none stored yet */
static int osmux_circuit_get_last_stored_amr_ft(struct osmux_circuit *circuit)
{
struct msgb *last;
struct rtp_hdr *rtph;
struct amr_hdr *amrh;
uint32_t amr_len;
/* Have we seen any RTP packet in this batch before? */
if (llist_empty(&circuit->msg_list))
return -1;
OSMO_ASSERT(circuit->nmsgs > 0);
/* Get last RTP packet seen in this batch */
last = llist_entry(circuit->msg_list.prev, struct msgb, list);
rtph = osmo_rtp_get_hdr(last);
amrh = osmo_rtp_get_payload(rtph, last, &amr_len);
if (amrh == NULL)
return -1;
return amrh->ft;
}
/* returns: 1 if batch is full, 0 if batch still not full, negative on error. */
static int osmux_replay_lost_packets(struct osmux_circuit *circuit,
struct rtp_hdr *cur_rtph, int batch_factor)
{
int16_t diff;
struct msgb *last;
struct rtp_hdr *rtph;
int i, rc;
/* Have we seen any RTP packet in this batch before? */
if (llist_empty(&circuit->msg_list))
return 0;
/* Get last RTP packet seen in this batch */
last = llist_entry(circuit->msg_list.prev, struct msgb, list);
rtph = osmo_rtp_get_hdr(last);
if (rtph == NULL)
return -1;
diff = ntohs(cur_rtph->sequence) - ntohs(rtph->sequence);
/* Lifesaver: make sure bugs don't spawn lots of clones */
if (diff > 16)
diff = 16;
rc = 0;
/* If diff between last RTP packet seen and this one is > 1,
* then we lost several RTP packets, let's replay them.
*/
for (i=1; i<diff; i++) {
struct msgb *clone;
/* Clone last RTP packet seen */
clone = msgb_alloc(last->data_len, "RTP clone");
if (!clone)
continue;
memcpy(clone->data, last->data, last->len);
msgb_put(clone, last->len);
/* The original RTP message has been already sanity checked. */
rtph = osmo_rtp_get_hdr(clone);
/* Adjust sequence number and timestamp */
rtph->sequence = htons(ntohs(rtph->sequence) + i);
rtph->timestamp = htonl(ntohl(rtph->timestamp) +
DELTA_RTP_TIMESTAMP);
/* No more room in this batch, skip padding with more clones */
rc = osmux_batch_enqueue(clone, circuit, batch_factor);
if (rc != 0) {
msgb_free(clone);
return rc;
}
LOGP(DLMUX, LOGL_ERROR, "adding cloned RTP\n");
}
return rc;
}
static struct osmux_circuit *
osmux_batch_find_circuit(struct osmux_batch *batch, int ccid)
{
struct osmux_circuit *circuit;
llist_for_each_entry(circuit, &batch->circuit_list, head) {
if (circuit->ccid == ccid)
return circuit;
}
return NULL;
}
static void osmux_batch_del_circuit(struct osmux_batch *batch, struct osmux_circuit *circuit)
{
if (circuit->dummy)
batch->ndummy--;
llist_del(&circuit->head);
osmux_circuit_del_msgs(batch, circuit);
talloc_free(circuit);
}
/* returns: 1 if batch is full, 0 if batch still not full, negative on error. */
static int
osmux_batch_add(struct osmux_batch *batch, uint32_t batch_factor, struct msgb *msg,
struct rtp_hdr *rtph, int ccid)
{
int bytes = 0, amr_payload_len;
struct osmux_circuit *circuit;
struct msgb *cur;
int rc;
struct amr_hdr *amrh;
uint32_t amr_len;
circuit = osmux_batch_find_circuit(batch, ccid);
if (!circuit)
return -1;
/* We've seen the first RTP message, disable dummy padding */
if (circuit->dummy) {
circuit->dummy = 0;
batch->ndummy--;
}
amrh = osmo_rtp_get_payload(rtph, msg, &amr_len);
if (amrh == NULL)
return -1;
amr_payload_len = osmux_rtp_amr_payload_len(amrh, amr_len);
if (amr_payload_len < 0) {
LOGP(DLMUX, LOGL_NOTICE, "AMR payload invalid\n");
return -1;
}
/* Init of talkspurt (RTP M marker bit) needs to be in the first AMR slot
* of the OSMUX packet, enforce sending previous batch if required:
*/
if (rtph->marker && circuit->nmsgs != 0)
return 1;
/* Extra validation: check if this message already exists, should not
* happen but make sure we don't propagate duplicated messages.
*/
llist_for_each_entry(cur, &circuit->msg_list, list) {
struct rtp_hdr *rtph2 = osmo_rtp_get_hdr(cur);
if (rtph2 == NULL)
return -1;
/* Already exists message with this sequence, skip */
if (rtph2->sequence == rtph->sequence) {
LOGP(DLMUX, LOGL_ERROR, "already exists "
"message with seq=%u, skip it\n",
rtph->sequence);
return -1;
}
}
/* First check if there is room for this message in the batch */
/* First in batch comes after the batch header: */
if (circuit->nmsgs == 0)
bytes += sizeof(struct osmux_hdr);
/* If AMR FT changes in the middle of current batch a new header is
* required to adapt to size change: */
else if (osmux_circuit_get_last_stored_amr_ft(circuit) != amrh->ft)
bytes += sizeof(struct osmux_hdr);
bytes += amr_payload_len;
/* No room, sorry. You'll have to retry */
if (bytes > batch->remaining_bytes)
return 1;
/* Handle RTP packet loss scenario */
rc = osmux_replay_lost_packets(circuit, rtph, batch_factor);
if (rc != 0)
return rc;
/* This batch is full, force batch delivery */
rc = osmux_batch_enqueue(msg, circuit, batch_factor);
if (rc != 0)
return rc;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "adding msg with ssrc=%u to batch\n",
rtph->ssrc);
#endif
/* Update remaining room in this batch */
batch->remaining_bytes -= bytes;
if (batch->nmsgs == 0) {
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "osmux start timer batch\n");
#endif
osmo_timer_schedule(&batch->timer, 0,
batch_factor * DELTA_RTP_MSG);
}
batch->nmsgs++;
return 0;
}
/**
* osmux_xfrm_input - add RTP message to OSmux batch
* \param msg: RTP message that you want to batch into one OSmux message
*
* If 0 is returned, this indicates that the message has been batched and the
* msgb is now owned by the osmux layer.
* If negative value is returned, an error occurred and the message has been
* dropped (and freed).
* If 1 is returned, you have to invoke osmux_xfrm_input_deliver and try again.
*
* The function takes care of releasing the messages in case of error and
* when building the batch.
*/
int osmux_xfrm_input(struct osmux_in_handle *h, struct msgb *msg, int ccid)
{
int ret;
struct rtp_hdr *rtph;
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
/* Ignore too big RTP/RTCP messages, most likely forged. Sanity check
* to avoid a possible forever loop in the caller.
*/
if (msg->len > h->batch_size - sizeof(struct osmux_hdr)) {
LOGP(DLMUX, LOGL_NOTICE, "RTP payload too big (%u) for configured batch size (%u)\n",
msg->len, h->batch_size);
msgb_free(msg);
return -1;
}
rtph = osmo_rtp_get_hdr(msg);
if (rtph == NULL) {
LOGP(DLMUX, LOGL_NOTICE, "msg not containing an RTP header\n");
msgb_free(msg);
return -1;
}
switch(rtph->payload_type) {
case RTP_PT_RTCP:
LOGP(DLMUX, LOGL_INFO, "Dropping RTCP packet\n");
msgb_free(msg);
return 0;
default:
/* The RTP payload type is dynamically allocated,
* although we use static ones. Assume that we always
* receive AMR traffic.
*/
/* Add this RTP to the OSMUX batch */
ret = osmux_batch_add(batch, h->batch_factor,
msg, rtph, ccid);
if (ret < 0) {
/* Cannot put this message into the batch.
* Malformed, duplicated, OOM. Drop it and tell
* the upper layer that we have digest it.
*/
LOGP(DLMUX, LOGL_DEBUG, "Dropping RTP packet instead of adding to batch\n");
msgb_free(msg);
return ret;
}
h->stats.input_rtp_msgs++;
h->stats.input_rtp_bytes += msg->len;
break;
}
return ret;
}
void osmux_xfrm_input_init(struct osmux_in_handle *h)
{
struct osmux_batch *batch;
/* Default to osmux packet size if not specified */
if (h->batch_size == 0)
h->batch_size = OSMUX_BATCH_DEFAULT_MAX;
batch = talloc_zero(osmux_ctx, struct osmux_batch);
if (batch == NULL)
return;
INIT_LLIST_HEAD(&batch->circuit_list);
batch->remaining_bytes = h->batch_size;
osmo_timer_setup(&batch->timer, osmux_batch_timer_expired, h);
h->internal_data = (void *)batch;
LOGP(DLMUX, LOGL_DEBUG, "initialized osmux input converter\n");
}
int osmux_xfrm_input_open_circuit(struct osmux_in_handle *h, int ccid,
int dummy)
{
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
struct osmux_circuit *circuit;
circuit = osmux_batch_find_circuit(batch, ccid);
if (circuit != NULL) {
LOGP(DLMUX, LOGL_ERROR, "circuit %u already exists!\n", ccid);
return -1;
}
circuit = talloc_zero(osmux_ctx, struct osmux_circuit);
if (circuit == NULL) {
LOGP(DLMUX, LOGL_ERROR, "OOM on circuit %u\n", ccid);
return -1;
}
circuit->ccid = ccid;
circuit->seq = h->osmux_seq;
INIT_LLIST_HEAD(&circuit->msg_list);
llist_add_tail(&circuit->head, &batch->circuit_list);
if (dummy) {
circuit->dummy = dummy;
batch->ndummy++;
if (!osmo_timer_pending(&batch->timer))
osmo_timer_schedule(&batch->timer, 0,
h->batch_factor * DELTA_RTP_MSG);
}
return 0;
}
void osmux_xfrm_input_close_circuit(struct osmux_in_handle *h, int ccid)
{
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
struct osmux_circuit *circuit;
circuit = osmux_batch_find_circuit(batch, ccid);
if (circuit == NULL) {
LOGP(DLMUX, LOGL_NOTICE, "Unable to close circuit %d: Not found\n",
ccid);
return;
}
osmux_batch_del_circuit(batch, circuit);
}
void osmux_xfrm_input_fini(struct osmux_in_handle *h)
{
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
struct osmux_circuit *circuit, *next;
llist_for_each_entry_safe(circuit, next, &batch->circuit_list, head)
osmux_batch_del_circuit(batch, circuit);
osmo_timer_del(&batch->timer);
talloc_free(batch);
}
struct osmux_tx_handle {
struct osmo_timer_list timer;
struct msgb *msg;
void (*tx_cb)(struct msgb *msg, void *data);
void *data;
};
static int osmux_xfrm_output_talloc_destructor(struct osmux_out_handle *h)
{
osmux_xfrm_output_flush(h);
return 0;
}
/*! \brief Allocate a new osmux out handle
* \param[in] ctx talloc context to use when allocating the returned struct
* \return Allocated osmux out handle
*
* This object contains configuration and state to handle a specific CID in
* incoming network Osmux messages, repackaging the frames for that CID as RTP
* packets and pushing them up the protocol stack.
* Returned pointer can be freed with regular talloc_free, queue will be flushed
* and all internal data will be freed. */
struct osmux_out_handle *osmux_xfrm_output_alloc(void *ctx)
{
struct osmux_out_handle *h;
h = talloc_zero(ctx, struct osmux_out_handle);
OSMO_ASSERT(h);
h->rtp_seq = (uint16_t)random();
h->rtp_timestamp = (uint32_t)random();
h->rtp_ssrc = (uint32_t)random();
h->rtp_payload_type = 98;
INIT_LLIST_HEAD(&h->list);
osmo_timer_setup(&h->timer, osmux_xfrm_output_trigger, h);
talloc_set_destructor(h, osmux_xfrm_output_talloc_destructor);
return h;
}
/* DEPRECATED: Use osmux_xfrm_output_alloc() and osmux_xfrm_output_set_rtp_*() instead */
void osmux_xfrm_output_init2(struct osmux_out_handle *h, uint32_t rtp_ssrc, uint8_t rtp_payload_type)
{
memset(h, 0, sizeof(*h));
h->rtp_seq = (uint16_t)random();
h->rtp_timestamp = (uint32_t)random();
h->rtp_ssrc = rtp_ssrc;
h->rtp_payload_type = rtp_payload_type;
INIT_LLIST_HEAD(&h->list);
osmo_timer_setup(&h->timer, osmux_xfrm_output_trigger, h);
}
/* DEPRECATED: Use osmux_xfrm_output_alloc() and osmux_xfrm_output_set_rtp_*() instead */
void osmux_xfrm_output_init(struct osmux_out_handle *h, uint32_t rtp_ssrc)
{
/* backward compatibility with old users, where 98 was harcoded in osmux_rebuild_rtp() */
osmux_xfrm_output_init2(h, rtp_ssrc, 98);
}
/*! \brief Set transmission callback to call when a generated RTP packet is to be transmitted
* \param[in] h the osmux out handle handling a specific CID
* \param[in] osmuxh Buffer pointing to osmux frame header structure and AMR payload
* \return Number of generated RTP packets
*
* This Function sets the callback called by the interal timer set by
* osmux_xfrm_out_sched function.
*/
void osmux_xfrm_output_set_tx_cb(struct osmux_out_handle *h,
void (*tx_cb)(struct msgb *msg, void *data),
void *data)
{
h->tx_cb = tx_cb;
h->data = data;
}
/*! \brief Set callback to call when an RTP packet to be generated is to be allocated
* \param[in] h the osmux out handle handling a specific CID
* \param[in] cb User defined msgb alloc function for generated RTP pkts
* \param[in] cb_data Opaque data pointer set by user and passed in \ref cb
* \return msgb structure to be used to fill in generated RTP pkt content
*/
void osmux_xfrm_output_set_rtp_msgb_alloc_cb(struct osmux_out_handle *h,
rtp_msgb_alloc_cb_t cb,
void *cb_data)
{
h->rtp_msgb_alloc_cb = cb;
h->rtp_msgb_alloc_cb_data = cb_data;
}
/*! \brief Set SSRC of generated RTP packets from Osmux frames
* \param[in] h the osmux out handle handling a specific CID
* \param[in] rtp_ssrc the RTP SSRC to set
*/
void osmux_xfrm_output_set_rtp_ssrc(struct osmux_out_handle *h, uint32_t rtp_ssrc)
{
h->rtp_ssrc = rtp_ssrc;
}
/*! \brief Set Payload Type of generated RTP packets from Osmux frames
* \param[in] h the osmux out handle handling a specific CID
* \param[in] rtp_payload_type the RTP Payload Type to set
*/
void osmux_xfrm_output_set_rtp_pl_type(struct osmux_out_handle *h, uint32_t rtp_payload_type)
{
h->rtp_payload_type = rtp_payload_type;
}
#define SNPRINTF_BUFFER_SIZE(ret, remain, offset) \
if (ret < 0) \
ret = 0; \

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/*
* (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_input.c
* \brief Osmocom multiplex protocol helpers (input)
*/
/* This allows you to debug osmux message transformations (spamming) */
#if 0
#define DEBUG_MSG 0
#endif
/* delta time between two RTP messages (in microseconds) */
#define DELTA_RTP_MSG 20000
/* delta time between two RTP messages (in samples, 8kHz) */
#define DELTA_RTP_TIMESTAMP 160
static void *osmux_ctx;
static uint32_t osmux_ft_dummy_size(uint8_t amr_ft, uint8_t batch_factor)
{
return sizeof(struct osmux_hdr) + (osmo_amr_bytes(amr_ft) * batch_factor);
}
struct osmux_batch {
struct osmo_timer_list timer;
struct osmux_hdr *osmuxh;
struct llist_head circuit_list;
unsigned int remaining_bytes;
uint32_t nmsgs;
int ndummy;
};
struct osmux_circuit {
struct llist_head head;
int ccid;
struct llist_head msg_list;
int nmsgs;
int dummy;
uint8_t seq;
};
/* returns: 1 if batch is full, 0 if batch still not full, negative on error. */
static int osmux_batch_enqueue(struct msgb *msg, struct osmux_circuit *circuit,
uint8_t batch_factor)
{
/* Validate amount of messages per batch. The counter field of the
* osmux header is just 3 bits long, so make sure it doesn't overflow.
*/
OSMO_ASSERT(batch_factor <= 8);
if (circuit->nmsgs >= batch_factor) {
struct rtp_hdr *rtph;
rtph = osmo_rtp_get_hdr(msg);
if (rtph == NULL)
return -1;
LOGP(DLMUX, LOGL_DEBUG, "Batch is full for RTP sssrc=%u\n", rtph->ssrc);
return 1;
}
llist_add_tail(&msg->list, &circuit->msg_list);
circuit->nmsgs++;
return 0;
}
static void osmux_batch_dequeue(struct msgb *msg, struct osmux_circuit *circuit)
{
llist_del(&msg->list);
circuit->nmsgs--;
}
static void osmux_circuit_del_msgs(struct osmux_batch *batch, struct osmux_circuit *circuit)
{
struct msgb *cur, *tmp;
llist_for_each_entry_safe(cur, tmp, &circuit->msg_list, list) {
osmux_batch_dequeue(cur, circuit);
msgb_free(cur);
batch->nmsgs--;
}
}
struct osmux_input_state {
struct msgb *out_msg;
struct msgb *msg;
struct rtp_hdr *rtph;
struct amr_hdr *amrh;
uint32_t amr_payload_len;
struct osmux_circuit *circuit;
int add_osmux_hdr;
};
static int osmux_batch_put(struct osmux_batch *batch,
struct osmux_input_state *state)
{
if (state->add_osmux_hdr) {
struct osmux_hdr *osmuxh;
osmuxh = (struct osmux_hdr *)msgb_put(state->out_msg,
sizeof(struct osmux_hdr));
osmuxh->ft = OSMUX_FT_VOICE_AMR;
osmuxh->ctr = 0;
osmuxh->rtp_m = osmuxh->rtp_m || state->rtph->marker;
osmuxh->seq = state->circuit->seq++;
osmuxh->circuit_id = state->circuit->ccid;
osmuxh->amr_ft = state->amrh->ft;
/* annotate current osmux header */
batch->osmuxh = osmuxh;
} else {
if (batch->osmuxh->ctr == 0x7) {
LOGP(DLMUX, LOGL_ERROR, "cannot add msg=%p, "
"too many messages for this RTP ssrc=%u\n",
state->msg, state->rtph->ssrc);
return 0;
}
batch->osmuxh->ctr++;
}
/* For fields below, we only use the last included in batch and ignore any previous: */
batch->osmuxh->amr_cmr = state->amrh->cmr;
batch->osmuxh->amr_f = state->amrh->f;
batch->osmuxh->amr_q = state->amrh->q;
memcpy(state->out_msg->tail, osmo_amr_get_payload(state->amrh),
state->amr_payload_len);
msgb_put(state->out_msg, state->amr_payload_len);
return 0;
}
static void osmux_encode_dummy(struct osmux_batch *batch, uint8_t batch_factor,
struct osmux_input_state *state)
{
struct osmux_hdr *osmuxh;
/* TODO: This should be configurable at some point. */
uint32_t payload_size = osmux_ft_dummy_size(AMR_FT_3, batch_factor) -
sizeof(struct osmux_hdr);
osmuxh = (struct osmux_hdr *)state->out_msg->tail;
osmuxh->ft = OSMUX_FT_DUMMY;
osmuxh->ctr = batch_factor - 1;
osmuxh->amr_f = 0;
osmuxh->amr_q= 0;
osmuxh->seq = 0;
osmuxh->circuit_id = state->circuit->ccid;
osmuxh->amr_cmr = 0;
osmuxh->amr_ft = AMR_FT_3;
msgb_put(state->out_msg, sizeof(struct osmux_hdr));
memset(state->out_msg->tail, 0xff, payload_size);
msgb_put(state->out_msg, payload_size);
}
static struct msgb *osmux_build_batch(struct osmux_batch *batch,
uint32_t batch_size, uint8_t batch_factor)
{
struct msgb *batch_msg;
struct osmux_circuit *circuit;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "Now building batch\n");
#endif
batch_msg = msgb_alloc(batch_size, "osmux");
if (batch_msg == NULL) {
LOGP(DLMUX, LOGL_ERROR, "Not enough memory\n");
return NULL;
}
llist_for_each_entry(circuit, &batch->circuit_list, head) {
struct msgb *cur, *tmp;
int ctr = 0;
int prev_amr_ft;
if (circuit->dummy) {
struct osmux_input_state state = {
.out_msg = batch_msg,
.circuit = circuit,
};
osmux_encode_dummy(batch, batch_factor, &state);
continue;
}
llist_for_each_entry_safe(cur, tmp, &circuit->msg_list, list) {
struct osmux_input_state state = {
.msg = cur,
.out_msg = batch_msg,
.circuit = circuit,
};
uint32_t amr_len;
#ifdef DEBUG_MSG
char buf[4096];
osmo_rtp_snprintf(buf, sizeof(buf), cur);
buf[sizeof(buf)-1] = '\0';
LOGP(DLMUX, LOGL_DEBUG, "to BSC-NAT: %s\n", buf);
#endif
state.rtph = osmo_rtp_get_hdr(cur);
if (!state.rtph)
return NULL;
state.amrh = osmo_rtp_get_payload(state.rtph, state.msg, &amr_len);
if (!state.amrh)
return NULL;
state.amr_payload_len = amr_len - sizeof(struct amr_hdr);
if (ctr == 0) {
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "Add osmux header (First in batch)\n");
#endif
state.add_osmux_hdr = 1;
} else if (prev_amr_ft != state.amrh->ft) {
/* If AMR FT changed, we have to generate an extra batch osmux header: */
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "Add osmux header (New AMR FT)\n");
#endif
state.add_osmux_hdr = 1;
}
osmux_batch_put(batch, &state);
osmux_batch_dequeue(cur, circuit);
prev_amr_ft = state.amrh->ft;
ctr++;
msgb_free(cur);
batch->nmsgs--;
}
}
return batch_msg;
}
void osmux_xfrm_input_deliver(struct osmux_in_handle *h)
{
struct msgb *batch_msg;
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "invoking delivery function\n");
#endif
batch_msg = osmux_build_batch(batch, h->batch_size, h->batch_factor);
if (!batch_msg)
return;
h->stats.output_osmux_msgs++;
h->stats.output_osmux_bytes += batch_msg->len;
h->deliver(batch_msg, h->data);
osmo_timer_del(&batch->timer);
batch->remaining_bytes = h->batch_size;
if (batch->ndummy) {
osmo_timer_schedule(&batch->timer, 0,
h->batch_factor * DELTA_RTP_MSG);
}
}
static void osmux_batch_timer_expired(void *data)
{
struct osmux_in_handle *h = data;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "osmux_batch_timer_expired\n");
#endif
osmux_xfrm_input_deliver(h);
}
static int osmux_rtp_amr_payload_len(struct amr_hdr *amrh, uint32_t amr_len)
{
int amr_payload_len;
if (!osmo_amr_ft_valid(amrh->ft))
return -1;
amr_payload_len = amr_len - sizeof(struct amr_hdr);
/* The AMR payload does not fit with what we expect */
if (osmo_amr_bytes(amrh->ft) != amr_payload_len) {
LOGP(DLMUX, LOGL_ERROR,
"Bad AMR frame, expected %zd bytes, got %d bytes\n",
osmo_amr_bytes(amrh->ft), amr_len);
return -1;
}
return amr_payload_len;
}
/* Last stored AMR FT to be added in the current osmux batch. -1 if none stored yet */
static int osmux_circuit_get_last_stored_amr_ft(struct osmux_circuit *circuit)
{
struct msgb *last;
struct rtp_hdr *rtph;
struct amr_hdr *amrh;
uint32_t amr_len;
/* Have we seen any RTP packet in this batch before? */
if (llist_empty(&circuit->msg_list))
return -1;
OSMO_ASSERT(circuit->nmsgs > 0);
/* Get last RTP packet seen in this batch */
last = llist_entry(circuit->msg_list.prev, struct msgb, list);
rtph = osmo_rtp_get_hdr(last);
amrh = osmo_rtp_get_payload(rtph, last, &amr_len);
if (amrh == NULL)
return -1;
return amrh->ft;
}
/* returns: 1 if batch is full, 0 if batch still not full, negative on error. */
static int osmux_replay_lost_packets(struct osmux_circuit *circuit,
struct rtp_hdr *cur_rtph, int batch_factor)
{
int16_t diff;
struct msgb *last;
struct rtp_hdr *rtph;
int i, rc;
/* Have we seen any RTP packet in this batch before? */
if (llist_empty(&circuit->msg_list))
return 0;
/* Get last RTP packet seen in this batch */
last = llist_entry(circuit->msg_list.prev, struct msgb, list);
rtph = osmo_rtp_get_hdr(last);
if (rtph == NULL)
return -1;
diff = ntohs(cur_rtph->sequence) - ntohs(rtph->sequence);
/* Lifesaver: make sure bugs don't spawn lots of clones */
if (diff > 16)
diff = 16;
rc = 0;
/* If diff between last RTP packet seen and this one is > 1,
* then we lost several RTP packets, let's replay them.
*/
for (i=1; i<diff; i++) {
struct msgb *clone;
/* Clone last RTP packet seen */
clone = msgb_alloc(last->data_len, "RTP clone");
if (!clone)
continue;
memcpy(clone->data, last->data, last->len);
msgb_put(clone, last->len);
/* The original RTP message has been already sanity checked. */
rtph = osmo_rtp_get_hdr(clone);
/* Adjust sequence number and timestamp */
rtph->sequence = htons(ntohs(rtph->sequence) + i);
rtph->timestamp = htonl(ntohl(rtph->timestamp) +
DELTA_RTP_TIMESTAMP);
/* No more room in this batch, skip padding with more clones */
rc = osmux_batch_enqueue(clone, circuit, batch_factor);
if (rc != 0) {
msgb_free(clone);
return rc;
}
LOGP(DLMUX, LOGL_ERROR, "adding cloned RTP\n");
}
return rc;
}
static struct osmux_circuit *
osmux_batch_find_circuit(struct osmux_batch *batch, int ccid)
{
struct osmux_circuit *circuit;
llist_for_each_entry(circuit, &batch->circuit_list, head) {
if (circuit->ccid == ccid)
return circuit;
}
return NULL;
}
static void osmux_batch_del_circuit(struct osmux_batch *batch, struct osmux_circuit *circuit)
{
if (circuit->dummy)
batch->ndummy--;
llist_del(&circuit->head);
osmux_circuit_del_msgs(batch, circuit);
talloc_free(circuit);
}
/* returns: 1 if batch is full, 0 if batch still not full, negative on error. */
static int
osmux_batch_add(struct osmux_batch *batch, uint32_t batch_factor, struct msgb *msg,
struct rtp_hdr *rtph, int ccid)
{
int bytes = 0, amr_payload_len;
struct osmux_circuit *circuit;
struct msgb *cur;
int rc;
struct amr_hdr *amrh;
uint32_t amr_len;
circuit = osmux_batch_find_circuit(batch, ccid);
if (!circuit)
return -1;
/* We've seen the first RTP message, disable dummy padding */
if (circuit->dummy) {
circuit->dummy = 0;
batch->ndummy--;
}
amrh = osmo_rtp_get_payload(rtph, msg, &amr_len);
if (amrh == NULL)
return -1;
amr_payload_len = osmux_rtp_amr_payload_len(amrh, amr_len);
if (amr_payload_len < 0) {
LOGP(DLMUX, LOGL_NOTICE, "AMR payload invalid\n");
return -1;
}
/* Init of talkspurt (RTP M marker bit) needs to be in the first AMR slot
* of the OSMUX packet, enforce sending previous batch if required:
*/
if (rtph->marker && circuit->nmsgs != 0)
return 1;
/* Extra validation: check if this message already exists, should not
* happen but make sure we don't propagate duplicated messages.
*/
llist_for_each_entry(cur, &circuit->msg_list, list) {
struct rtp_hdr *rtph2 = osmo_rtp_get_hdr(cur);
if (rtph2 == NULL)
return -1;
/* Already exists message with this sequence, skip */
if (rtph2->sequence == rtph->sequence) {
LOGP(DLMUX, LOGL_ERROR, "already exists "
"message with seq=%u, skip it\n",
rtph->sequence);
return -1;
}
}
/* First check if there is room for this message in the batch */
/* First in batch comes after the batch header: */
if (circuit->nmsgs == 0)
bytes += sizeof(struct osmux_hdr);
/* If AMR FT changes in the middle of current batch a new header is
* required to adapt to size change: */
else if (osmux_circuit_get_last_stored_amr_ft(circuit) != amrh->ft)
bytes += sizeof(struct osmux_hdr);
bytes += amr_payload_len;
/* No room, sorry. You'll have to retry */
if (bytes > batch->remaining_bytes)
return 1;
/* Handle RTP packet loss scenario */
rc = osmux_replay_lost_packets(circuit, rtph, batch_factor);
if (rc != 0)
return rc;
/* This batch is full, force batch delivery */
rc = osmux_batch_enqueue(msg, circuit, batch_factor);
if (rc != 0)
return rc;
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "adding msg with ssrc=%u to batch\n",
rtph->ssrc);
#endif
/* Update remaining room in this batch */
batch->remaining_bytes -= bytes;
if (batch->nmsgs == 0) {
#ifdef DEBUG_MSG
LOGP(DLMUX, LOGL_DEBUG, "osmux start timer batch\n");
#endif
osmo_timer_schedule(&batch->timer, 0,
batch_factor * DELTA_RTP_MSG);
}
batch->nmsgs++;
return 0;
}
/**
* osmux_xfrm_input - add RTP message to OSmux batch
* \param msg: RTP message that you want to batch into one OSmux message
*
* If 0 is returned, this indicates that the message has been batched and the
* msgb is now owned by the osmux layer.
* If negative value is returned, an error occurred and the message has been
* dropped (and freed).
* If 1 is returned, you have to invoke osmux_xfrm_input_deliver and try again.
*
* The function takes care of releasing the messages in case of error and
* when building the batch.
*/
int osmux_xfrm_input(struct osmux_in_handle *h, struct msgb *msg, int ccid)
{
int ret;
struct rtp_hdr *rtph;
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
/* Ignore too big RTP/RTCP messages, most likely forged. Sanity check
* to avoid a possible forever loop in the caller.
*/
if (msg->len > h->batch_size - sizeof(struct osmux_hdr)) {
LOGP(DLMUX, LOGL_NOTICE, "RTP payload too big (%u) for configured batch size (%u)\n",
msg->len, h->batch_size);
msgb_free(msg);
return -1;
}
rtph = osmo_rtp_get_hdr(msg);
if (rtph == NULL) {
LOGP(DLMUX, LOGL_NOTICE, "msg not containing an RTP header\n");
msgb_free(msg);
return -1;
}
switch(rtph->payload_type) {
case RTP_PT_RTCP:
LOGP(DLMUX, LOGL_INFO, "Dropping RTCP packet\n");
msgb_free(msg);
return 0;
default:
/* The RTP payload type is dynamically allocated,
* although we use static ones. Assume that we always
* receive AMR traffic.
*/
/* Add this RTP to the OSMUX batch */
ret = osmux_batch_add(batch, h->batch_factor,
msg, rtph, ccid);
if (ret < 0) {
/* Cannot put this message into the batch.
* Malformed, duplicated, OOM. Drop it and tell
* the upper layer that we have digest it.
*/
LOGP(DLMUX, LOGL_DEBUG, "Dropping RTP packet instead of adding to batch\n");
msgb_free(msg);
return ret;
}
h->stats.input_rtp_msgs++;
h->stats.input_rtp_bytes += msg->len;
break;
}
return ret;
}
void osmux_xfrm_input_init(struct osmux_in_handle *h)
{
struct osmux_batch *batch;
/* Default to osmux packet size if not specified */
if (h->batch_size == 0)
h->batch_size = OSMUX_BATCH_DEFAULT_MAX;
batch = talloc_zero(osmux_ctx, struct osmux_batch);
if (batch == NULL)
return;
INIT_LLIST_HEAD(&batch->circuit_list);
batch->remaining_bytes = h->batch_size;
osmo_timer_setup(&batch->timer, osmux_batch_timer_expired, h);
h->internal_data = (void *)batch;
LOGP(DLMUX, LOGL_DEBUG, "initialized osmux input converter\n");
}
int osmux_xfrm_input_open_circuit(struct osmux_in_handle *h, int ccid,
int dummy)
{
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
struct osmux_circuit *circuit;
circuit = osmux_batch_find_circuit(batch, ccid);
if (circuit != NULL) {
LOGP(DLMUX, LOGL_ERROR, "circuit %u already exists!\n", ccid);
return -1;
}
circuit = talloc_zero(osmux_ctx, struct osmux_circuit);
if (circuit == NULL) {
LOGP(DLMUX, LOGL_ERROR, "OOM on circuit %u\n", ccid);
return -1;
}
circuit->ccid = ccid;
circuit->seq = h->osmux_seq;
INIT_LLIST_HEAD(&circuit->msg_list);
llist_add_tail(&circuit->head, &batch->circuit_list);
if (dummy) {
circuit->dummy = dummy;
batch->ndummy++;
if (!osmo_timer_pending(&batch->timer))
osmo_timer_schedule(&batch->timer, 0,
h->batch_factor * DELTA_RTP_MSG);
}
return 0;
}
void osmux_xfrm_input_close_circuit(struct osmux_in_handle *h, int ccid)
{
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
struct osmux_circuit *circuit;
circuit = osmux_batch_find_circuit(batch, ccid);
if (circuit == NULL) {
LOGP(DLMUX, LOGL_NOTICE, "Unable to close circuit %d: Not found\n",
ccid);
return;
}
osmux_batch_del_circuit(batch, circuit);
}
void osmux_xfrm_input_fini(struct osmux_in_handle *h)
{
struct osmux_batch *batch = (struct osmux_batch *)h->internal_data;
struct osmux_circuit *circuit, *next;
llist_for_each_entry_safe(circuit, next, &batch->circuit_list, head)
osmux_batch_del_circuit(batch, circuit);
osmo_timer_del(&batch->timer);
talloc_free(batch);
}
/*! @} */

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/*
* (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_output.c
* \brief Osmocom multiplex protocol helpers (output)
*/
/* delta time between two RTP messages (in microseconds) */
#define DELTA_RTP_MSG 20000
/* delta time between two RTP messages (in samples, 8kHz) */
#define DELTA_RTP_TIMESTAMP 160
static uint32_t osmux_ft_dummy_size(uint8_t amr_ft, uint8_t batch_factor)
{
return sizeof(struct osmux_hdr) + (osmo_amr_bytes(amr_ft) * batch_factor);
}
struct osmux_hdr *osmux_xfrm_output_pull(struct msgb *msg)
{
struct osmux_hdr *osmuxh;
next:
osmuxh = NULL;
if (msg->len > sizeof(struct osmux_hdr)) {
size_t len;
osmuxh = (struct osmux_hdr *)msg->data;
switch (osmuxh->ft) {
case OSMUX_FT_VOICE_AMR:
break;
case OSMUX_FT_DUMMY:
len = osmux_ft_dummy_size(osmuxh->amr_ft, osmuxh->ctr + 1);
if (msgb_length(msg) < len) {
LOGP(DLMUX, LOGL_ERROR, "Discarding bad Dummy FT: %s\n",
osmo_hexdump(msg->data, msgb_length(msg)));
return NULL;
}
msgb_pull(msg, len);
goto next;
default:
LOGP(DLMUX, LOGL_ERROR, "Discarding unsupported Osmux FT %d\n",
osmuxh->ft);
return NULL;
}
if (!osmo_amr_ft_valid(osmuxh->amr_ft)) {
LOGP(DLMUX, LOGL_ERROR, "Discarding bad AMR FT %d\n",
osmuxh->amr_ft);
return NULL;
}
len = osmo_amr_bytes(osmuxh->amr_ft) * (osmuxh->ctr+1) +
sizeof(struct osmux_hdr);
if (msgb_length(msg) < len) {
LOGP(DLMUX, LOGL_ERROR,
"Discarding malformed OSMUX message: %s\n",
osmo_hexdump(msg->data, msgb_length(msg)));
return NULL;
}
msgb_pull(msg, len);
} else if (msg->len > 0) {
LOGP(DLMUX, LOGL_ERROR,
"remaining %d bytes, broken osmuxhdr?\n", msg->len);
}
return osmuxh;
}
static struct msgb *
osmux_rebuild_rtp(struct osmux_out_handle *h, struct osmux_hdr *osmuxh,
void *payload, int payload_len, bool first_pkt)
{
struct msgb *prev_msg, *out_msg;
struct timespec *prev_ts, *out_ts;
struct rtp_hdr *rtph;
struct amr_hdr *amrh;
struct timespec delta = { .tv_sec = 0, .tv_nsec = DELTA_RTP_MSG*1000 };
unsigned int msg_len = sizeof(struct rtp_hdr) +
sizeof(struct amr_hdr) +
payload_len;
if (h->rtp_msgb_alloc_cb) {
out_msg = h->rtp_msgb_alloc_cb(h->rtp_msgb_alloc_cb_data, msg_len);
} else {
out_msg = msgb_alloc(msg_len, "osmux-rtp");
}
if (out_msg == NULL)
return NULL;
/* Reconstruct RTP header */
rtph = (struct rtp_hdr *)out_msg->data;
rtph->csrc_count = 0;
rtph->extension = 0;
rtph->version = RTP_VERSION;
rtph->payload_type = h->rtp_payload_type;
/* ... emulate timestamp and ssrc */
rtph->timestamp = htonl(h->rtp_timestamp);
rtph->sequence = htons(h->rtp_seq);
rtph->ssrc = htonl(h->rtp_ssrc);
/* rtp packet with the marker bit is always guaranteed to be the first
* one. We want to notify with marker in 2 scenarios:
* 1- Sender told us through osmux frame rtp_m.
* 2- Intermediate osmux frame lost (seq gap), otherwise rtp receiver only sees
* steady increase of delay
*/
rtph->marker = first_pkt &&
(osmuxh->rtp_m || (osmuxh->seq != ((h->osmux_seq_ack + 1) & 0xff)));
msgb_put(out_msg, sizeof(struct rtp_hdr));
/* Reconstruct AMR header */
amrh = (struct amr_hdr *)out_msg->tail;
amrh->cmr = osmuxh->amr_cmr;
amrh->f = osmuxh->amr_f;
amrh->ft = osmuxh->amr_ft;
amrh->q = osmuxh->amr_q;
msgb_put(out_msg, sizeof(struct amr_hdr));
/* add AMR speech data */
memcpy(out_msg->tail, payload, payload_len);
msgb_put(out_msg, payload_len);
/* bump last RTP sequence number and timestamp that has been used */
h->rtp_seq++;
h->rtp_timestamp += DELTA_RTP_TIMESTAMP;
out_ts = ((struct timespec *)&((out_msg)->cb[0]));
if (first_pkt || llist_empty(&h->list)) {
osmo_clock_gettime(CLOCK_MONOTONIC, out_ts);
} else {
prev_msg = llist_last_entry(&h->list, struct msgb, list);
prev_ts = ((struct timespec *)&((prev_msg)->cb[0]));
timespecadd(prev_ts, &delta, out_ts);
}
return out_msg;
}
static void osmux_xfrm_output_trigger(void *data)
{
struct osmux_out_handle *h = data;
struct timespec delay_ts, now;
struct msgb *msg, *next;
llist_for_each_entry_safe(msg, next, &h->list, list) {
osmo_clock_gettime(CLOCK_MONOTONIC, &now);
struct timespec *msg_ts = ((struct timespec *)&((msg)->cb[0]));
if (timespeccmp(msg_ts, &now, >)) {
timespecsub(msg_ts, &now, &delay_ts);
osmo_timer_schedule(&h->timer,
delay_ts.tv_sec, delay_ts.tv_nsec / 1000);
return;
}
/* Transmit the rtp packet */
llist_del(&msg->list);
if (h->tx_cb)
h->tx_cb(msg, h->data);
else
msgb_free(msg);
}
}
/*! \brief Generate RTP packets from osmux frame AMR payload set and schedule
* them for transmission at appropiate time.
* \param[in] h the osmux out handle handling a specific CID
* \param[in] osmuxh Buffer pointing to osmux frame header structure and AMR payload
* \return Number of generated RTP packets
*
* The osmux frame passed to this function must be of the type OSMUX_FT_VOICE_AMR.
* The generated RTP packets are kept into h's internal list and sent to the
* callback configured through osmux_xfrm_output_set_tx_cb when are ready to be
* transmitted according to schedule.
*/
int osmux_xfrm_output_sched(struct osmux_out_handle *h, struct osmux_hdr *osmuxh)
{
struct timespec now, *msg_ts;
struct msgb *msg;
int i;
bool was_empty = llist_empty(&h->list);
if (!was_empty) {
/* If we received new data it means we are behind schedule and
* we should flush all previous quickly */
osmo_clock_gettime(CLOCK_MONOTONIC, &now);
llist_for_each_entry(msg, &h->list, list) {
msg_ts = ((struct timespec *)&((msg)->cb[0]));
*msg_ts = now;
}
osmo_timer_schedule(&h->timer, 0, 0);
}
for (i = 0; i < osmuxh->ctr + 1; i++) {
struct rtp_hdr *rtph;
msg = osmux_rebuild_rtp(h, osmuxh,
osmux_get_payload(osmuxh) +
i * osmo_amr_bytes(osmuxh->amr_ft),
osmo_amr_bytes(osmuxh->amr_ft), !i);
if (msg == NULL)
continue;
rtph = osmo_rtp_get_hdr(msg);
if (rtph == NULL)
continue;
llist_add_tail(&msg->list, &h->list);
}
/* Update last seen seq number: */
h->osmux_seq_ack = osmuxh->seq;
/* In case list is still empty after parsing messages, no need to rearm */
if(was_empty && !llist_empty(&h->list))
osmux_xfrm_output_trigger(h);
return i;
}
/*! \brief Flush all scheduled RTP packets still pending to be transmitted
* \param[in] h the osmux out handle to flush
*
* This function will immediately call the transmit callback for all queued RTP
* packets, making sure the list ends up empty. It will also stop all internal
* timers to make sure the osmux_out_handle can be dropped or re-used by calling
* osmux_xfrm_output on it.
*/
void osmux_xfrm_output_flush(struct osmux_out_handle *h)
{
struct msgb *msg, *next;
if (osmo_timer_pending(&h->timer))
osmo_timer_del(&h->timer);
llist_for_each_entry_safe(msg, next, &h->list, list) {
llist_del(&msg->list);
if (h->tx_cb)
h->tx_cb(msg, h->data);
else
msgb_free(msg);
}
}
struct osmux_tx_handle {
struct osmo_timer_list timer;
struct msgb *msg;
void (*tx_cb)(struct msgb *msg, void *data);
void *data;
};
static int osmux_xfrm_output_talloc_destructor(struct osmux_out_handle *h)
{
osmux_xfrm_output_flush(h);
return 0;
}
/*! \brief Allocate a new osmux out handle
* \param[in] ctx talloc context to use when allocating the returned struct
* \return Allocated osmux out handle
*
* This object contains configuration and state to handle a specific CID in
* incoming network Osmux messages, repackaging the frames for that CID as RTP
* packets and pushing them up the protocol stack.
* Returned pointer can be freed with regular talloc_free, queue will be flushed
* and all internal data will be freed. */
struct osmux_out_handle *osmux_xfrm_output_alloc(void *ctx)
{
struct osmux_out_handle *h;
h = talloc_zero(ctx, struct osmux_out_handle);
OSMO_ASSERT(h);
h->rtp_seq = (uint16_t)random();
h->rtp_timestamp = (uint32_t)random();
h->rtp_ssrc = (uint32_t)random();
h->rtp_payload_type = 98;
INIT_LLIST_HEAD(&h->list);
osmo_timer_setup(&h->timer, osmux_xfrm_output_trigger, h);
talloc_set_destructor(h, osmux_xfrm_output_talloc_destructor);
return h;
}
/* DEPRECATED: Use osmux_xfrm_output_alloc() and osmux_xfrm_output_set_rtp_*() instead */
void osmux_xfrm_output_init2(struct osmux_out_handle *h, uint32_t rtp_ssrc, uint8_t rtp_payload_type)
{
memset(h, 0, sizeof(*h));
h->rtp_seq = (uint16_t)random();
h->rtp_timestamp = (uint32_t)random();
h->rtp_ssrc = rtp_ssrc;
h->rtp_payload_type = rtp_payload_type;
INIT_LLIST_HEAD(&h->list);
osmo_timer_setup(&h->timer, osmux_xfrm_output_trigger, h);
}
/* DEPRECATED: Use osmux_xfrm_output_alloc() and osmux_xfrm_output_set_rtp_*() instead */
void osmux_xfrm_output_init(struct osmux_out_handle *h, uint32_t rtp_ssrc)
{
/* backward compatibility with old users, where 98 was harcoded in osmux_rebuild_rtp() */
osmux_xfrm_output_init2(h, rtp_ssrc, 98);
}
/*! \brief Set transmission callback to call when a generated RTP packet is to be transmitted
* \param[in] h the osmux out handle handling a specific CID
* \param[in] osmuxh Buffer pointing to osmux frame header structure and AMR payload
* \return Number of generated RTP packets
*
* This Function sets the callback called by the interal timer set by
* osmux_xfrm_out_sched function.
*/
void osmux_xfrm_output_set_tx_cb(struct osmux_out_handle *h,
void (*tx_cb)(struct msgb *msg, void *data),
void *data)
{
h->tx_cb = tx_cb;
h->data = data;
}
/*! \brief Set callback to call when an RTP packet to be generated is to be allocated
* \param[in] h the osmux out handle handling a specific CID
* \param[in] cb User defined msgb alloc function for generated RTP pkts
* \param[in] cb_data Opaque data pointer set by user and passed in \ref cb
* \return msgb structure to be used to fill in generated RTP pkt content
*/
void osmux_xfrm_output_set_rtp_msgb_alloc_cb(struct osmux_out_handle *h,
rtp_msgb_alloc_cb_t cb,
void *cb_data)
{
h->rtp_msgb_alloc_cb = cb;
h->rtp_msgb_alloc_cb_data = cb_data;
}
/*! \brief Set SSRC of generated RTP packets from Osmux frames
* \param[in] h the osmux out handle handling a specific CID
* \param[in] rtp_ssrc the RTP SSRC to set
*/
void osmux_xfrm_output_set_rtp_ssrc(struct osmux_out_handle *h, uint32_t rtp_ssrc)
{
h->rtp_ssrc = rtp_ssrc;
}
/*! \brief Set Payload Type of generated RTP packets from Osmux frames
* \param[in] h the osmux out handle handling a specific CID
* \param[in] rtp_payload_type the RTP Payload Type to set
*/
void osmux_xfrm_output_set_rtp_pl_type(struct osmux_out_handle *h, uint32_t rtp_payload_type)
{
h->rtp_payload_type = rtp_payload_type;
}
/*! @} */