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/*
* (C) 2011 by Holger Hans Peter Freyther <zecke@selfish.org>
* (C) 2011 by On-Waves
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <openbsc/debug.h>
#include <openbsc/rtp_rfc.h>
#include <openbsc/mgcp_internal.h>
#include <osmocom/core/talloc.h>
#include <string.h>
struct reduced_rtp_hdr {
/** I will need to be inflated to the SSRC */
uint8_t endp;
/** I will need to be inflated to both the TS and the Sequence Number */
uint8_t sequence_no;
/**
* I represent the type, you should know the size of each payload now.
* I represent the number of payloads that follow
*/
uint8_t type : 4,
payloads : 4;
uint8_t data[0];
} __attribute__((packed));
#define msgb_put_struct(msg, str) \
(str *) msgb_put(msg, sizeof(str))
static void fill_rtp_hdr(struct rtp_hdr *hdr)
{
hdr->csrc_count = 0;
hdr->extension = 0;
hdr->padding = 0;
hdr->version = RTP_VERSION;
/* detect stop of silence? */
hdr->marker = 0;
hdr->payload_type = 98;
}
static void fill_rtp_state(struct rtp_hdr *hdr,
struct mgcp_rtp_compr_state *state)
{
hdr->ssrc = htonl(state->generated_ssrc);
hdr->sequence = htons(state->sequence++);
hdr->timestamp = htonl(state->timestamp);
state->timestamp += 160;
}
/**
* I try to compress these packets into one single stream. I have various
* limitations. I do not support packets that jump backwards, the rtp_packets
* list must be properly sorted, everything else will be discarded.
*
* Also somethings like:
* seq_no:1, seq_no:3, seq_no: 5
* will be folded into
* 3 payloads, Payload:1, Payload:2, Payload:3
*
* And the decoder will decode it to:
* seq_no:1, seq_no:2, seq_no: 3
*
*/
int rtp_compress(struct mgcp_rtp_compr_state *state, struct msgb *msg,
int endp, struct llist_head *rtp_packets)
{
struct msgb *rtp, *tmp;
struct reduced_rtp_hdr *reduced_hdr;
uint16_t last_sequence = 0;
int count = 0;
uint8_t *data;
/*
* sanity check if everything is a RTP packet
*/
llist_for_each_entry_safe(rtp, tmp, rtp_packets, list) {
struct rtp_hdr *hdr;
uint16_t sequence;
if (msgb_l2len(rtp) < sizeof(struct rtp_hdr)) {
LOGP(DMGCP, LOGL_ERROR,
"Packet is too small on %d/0x%x\n", endp, endp);
llist_del(&rtp->list);
talloc_free(rtp);
continue;
}
if (msgb_l2len(rtp) < sizeof(struct rtp_hdr) + 17) {
LOGP(DMGCP, LOGL_ERROR,
"We assume every payload is 17 byte: %d\n",
msgb_l2len(rtp) - sizeof(struct rtp_hdr));
llist_del(&rtp->list);
talloc_free(rtp);
continue;
}
hdr = (struct rtp_hdr *) rtp->l2h;
sequence = ntohs(hdr->sequence);
if (sequence < last_sequence && sequence != 0) {
LOGP(DMGCP, LOGL_ERROR, "Packet is not in sequence.\n");
llist_del(&rtp->list);
talloc_free(rtp);
last_sequence = sequence;
continue;
}
last_sequence = sequence;
count += 1;
}
if (llist_empty(rtp_packets))
return 0;
reduced_hdr = msgb_put_struct(msg, struct reduced_rtp_hdr);
reduced_hdr->endp = endp;
reduced_hdr->sequence_no = ++state->last_ts % UCHAR_MAX;
reduced_hdr->type = 0;
reduced_hdr->payloads = count;
llist_for_each_entry_safe(rtp, tmp, rtp_packets, list) {
struct rtp_hdr *hdr = (struct rtp_hdr *) rtp->l2h;
uint32_t len = msgb_l2len(rtp) - sizeof(*hdr);
data = msgb_put(msg, len);
memcpy(data, hdr->data, len);
llist_del(&rtp->list);
talloc_free(rtp);
}
return count;
}
struct llist_head rtp_decompress(struct mgcp_rtp_compr_state *state,
struct msgb *msg)
{
struct reduced_rtp_hdr *rhdr;
int i;
struct llist_head list;
INIT_LLIST_HEAD(&list);
if (msgb_l2len(msg) < sizeof(*rhdr)) {
LOGP(DMGCP, LOGL_ERROR, "Compressed header does not fit.\n");
return list;
}
rhdr = (struct reduced_rtp_hdr *) msg->l2h;
if (rhdr->type != 0) {
LOGP(DMGCP, LOGL_ERROR,
"Type %d is not known.\n", rhdr->type);
return list;
}
if (msgb_l2len(msg) < sizeof(*rhdr) + rhdr->payloads * 17) {
LOGP(DMGCP, LOGL_ERROR,
"Payloads do not fit. %d\n", rhdr->payloads);
return list;
}
for (i = 0; i < rhdr->payloads; ++i) {
struct rtp_hdr *hdr;
struct msgb *out = msgb_alloc_headroom(4096, 128, "RTP decompr");
if (!out) {
LOGP(DMGCP, LOGL_ERROR, "Failed to allocate: %d\n", i);
continue;
}
out->l2h = msgb_put(out, 0);
hdr = msgb_put_struct(out, struct rtp_hdr);
fill_rtp_hdr(hdr);
fill_rtp_state(hdr, state);
out->l3h = msgb_put(out, 17);
memcpy(out->l3h, &rhdr->data[i * 17], 17);
msgb_enqueue(&list, out);
}
return list;
}
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