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res_rtp_asterisk: Force resync on SSRC change. 

When an SSRC change occurs the timestamps are likely
to change as well. As a result we need to reset the
timestamp mapping done in the calc_rxstamp function
so that they map properly from timestamp to real
time.

This previously occurred but due to packet
retransmission support the explicit setting
of the marker bit was not effective.

ASTERISK-29352

Change-Id: I2d4c8f93ea24abc1030196706de2d70facf05a5a
This commit is contained in:
Joshua C. Colp 2021-03-17 12:28:45 -03:00 committed by Joshua Colp
parent 6aac148d59
commit 2e7fc84398
1 changed files with 51 additions and 47 deletions
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98
res/res_rtp_asterisk.c
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@ -7203,12 +7203,13 @@ static void rtp_instance_parse_extmap_extensions(struct ast_rtp_instance *instan
}
static struct ast_frame *ast_rtp_interpret(struct ast_rtp_instance *instance, struct ast_srtp *srtp,
const struct ast_sockaddr *remote_address, unsigned char *read_area, int length, int prev_seqno)
const struct ast_sockaddr *remote_address, unsigned char *read_area, int length, int prev_seqno,
unsigned int bundled)
{
unsigned int *rtpheader = (unsigned int*)(read_area);
struct ast_rtp *rtp = ast_rtp_instance_get_data(instance);
struct ast_rtp_instance *instance1;
int res = length, hdrlen = 12, seqno, payloadtype, padding, mark, ext, cc;
int res = length, hdrlen = 12, ssrc, seqno, payloadtype, padding, mark, ext, cc;
unsigned int timestamp;
RAII_VAR(struct ast_rtp_payload_type *, payload, NULL, ao2_cleanup);
struct frame_list frames;
@ -7225,6 +7226,7 @@ static struct ast_frame *ast_rtp_interpret(struct ast_rtp_instance *instance, st
}
/* Pull out the various other fields we will need */
ssrc = ntohl(rtpheader[2]);
seqno = ntohl(rtpheader[0]);
payloadtype = (seqno & 0x7f0000) >> 16;
padding = seqno & (1 << 29);
@ -7274,6 +7276,42 @@ static struct ast_frame *ast_rtp_interpret(struct ast_rtp_instance *instance, st
return AST_LIST_FIRST(&frames) ? AST_LIST_FIRST(&frames) : &ast_null_frame;
}
/* Only non-bundled instances can change/learn the remote's SSRC implicitly. */
if (!bundled) {
/* Force a marker bit and change SSRC if the SSRC changes */
if (rtp->themssrc_valid && rtp->themssrc != ssrc) {
struct ast_frame *f, srcupdate = {
AST_FRAME_CONTROL,
.subclass.integer = AST_CONTROL_SRCCHANGE,
};
if (!mark) {
if (ast_debug_rtp_packet_is_allowed) {
ast_debug(0, "(%p) RTP forcing Marker bit, because SSRC has changed\n", instance);
}
mark = 1;
}
f = ast_frisolate(&srcupdate);
AST_LIST_INSERT_TAIL(&frames, f, frame_list);
rtp->seedrxseqno = 0;
rtp->rxcount = 0;
rtp->rxoctetcount = 0;
rtp->cycles = 0;
prev_seqno = 0;
rtp->last_seqno = 0;
rtp->last_end_timestamp = 0;
if (rtp->rtcp) {
rtp->rtcp->expected_prior = 0;
rtp->rtcp->received_prior = 0;
}
}
rtp->themssrc = ssrc; /* Record their SSRC to put in future RR */
rtp->themssrc_valid = 1;
}
rtp->rxcount++;
rtp->rxoctetcount += (res - hdrlen);
if (rtp->rxcount == 1) {
@ -7498,13 +7536,14 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
struct ast_srtp *srtp;
RAII_VAR(struct ast_rtp_instance *, child, NULL, rtp_instance_unlock);
struct ast_sockaddr addr;
int res, hdrlen = 12, version, payloadtype, mark;
int res, hdrlen = 12, version, payloadtype;
unsigned char *read_area = rtp->rawdata + AST_FRIENDLY_OFFSET;
size_t read_area_size = sizeof(rtp->rawdata) - AST_FRIENDLY_OFFSET;
unsigned int *rtpheader = (unsigned int*)(read_area), seqno, ssrc, timestamp, prev_seqno;
struct ast_sockaddr remote_address = { {0,} };
struct frame_list frames;
struct ast_frame *frame;
unsigned int bundled;
/* If this is actually RTCP let's hop on over and handle it */
if (rtcp) {
@ -7781,7 +7820,6 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
/* Pull out the various other fields we will need */
payloadtype = (seqno & 0x7f0000) >> 16;
mark = seqno & (1 << 23);
seqno &= 0xffff;
timestamp = ntohl(rtpheader[1]);
@ -7793,48 +7831,14 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
AST_LIST_HEAD_INIT_NOLOCK(&frames);
/* Only non-bundled instances can change/learn the remote's SSRC implicitly. */
if (!child && !AST_VECTOR_SIZE(&rtp->ssrc_mapping)) {
/* Force a marker bit and change SSRC if the SSRC changes */
if (rtp->themssrc_valid && rtp->themssrc != ssrc) {
struct ast_frame *f, srcupdate = {
AST_FRAME_CONTROL,
.subclass.integer = AST_CONTROL_SRCCHANGE,
};
if (!mark) {
if (ast_debug_rtp_packet_is_allowed) {
ast_debug(0, "(%p) RTP forcing Marker bit, because SSRC has changed\n", instance);
}
mark = 1;
}
f = ast_frisolate(&srcupdate);
AST_LIST_INSERT_TAIL(&frames, f, frame_list);
rtp->seedrxseqno = 0;
rtp->rxcount = 0;
rtp->rxoctetcount = 0;
rtp->cycles = 0;
rtp->lastrxseqno = 0;
rtp->last_seqno = 0;
rtp->last_end_timestamp = 0;
if (rtp->rtcp) {
rtp->rtcp->expected_prior = 0;
rtp->rtcp->received_prior = 0;
}
}
rtp->themssrc = ssrc; /* Record their SSRC to put in future RR */
rtp->themssrc_valid = 1;
}
bundled = (child || AST_VECTOR_SIZE(&rtp->ssrc_mapping)) ? 1 : 0;
prev_seqno = rtp->lastrxseqno;
rtp->lastrxseqno = seqno;
if (!rtp->recv_buffer) {
/* If there is no receive buffer then we can pass back the frame directly */
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno);
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno, bundled);
AST_LIST_INSERT_TAIL(&frames, frame, frame_list);
return AST_LIST_FIRST(&frames);
} else if (rtp->expectedrxseqno == -1 || seqno == rtp->expectedrxseqno) {
@ -7849,7 +7853,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
* return it directly without duplicating it.
*/
if (!ast_data_buffer_count(rtp->recv_buffer)) {
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno);
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno, bundled);
AST_LIST_INSERT_TAIL(&frames, frame, frame_list);
return AST_LIST_FIRST(&frames);
}
@ -7864,7 +7868,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
* chance it will be overwritten.
*/
if (!ast_data_buffer_get(rtp->recv_buffer, rtp->expectedrxseqno)) {
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno);
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno, bundled);
AST_LIST_INSERT_TAIL(&frames, frame, frame_list);
return AST_LIST_FIRST(&frames);
}
@ -7874,7 +7878,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
* to the head of the frames list and avoid having to duplicate it but this would result in out
* of order packet processing by libsrtp which we are trying to avoid.
*/
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno));
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno, bundled));
if (frame) {
AST_LIST_INSERT_TAIL(&frames, frame, frame_list);
prev_seqno = seqno;
@ -7889,7 +7893,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
break;
}
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, payload->buf, payload->size, prev_seqno));
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, payload->buf, payload->size, prev_seqno, bundled));
ast_free(payload);
if (!frame) {
@ -7935,7 +7939,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
/* If the packet we received is the one we are expecting at this point then add it in */
if (rtp->expectedrxseqno == seqno) {
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno));
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno, bundled));
if (frame) {
AST_LIST_INSERT_TAIL(&frames, frame, frame_list);
prev_seqno = seqno;
@ -7960,7 +7964,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
payload = (struct ast_rtp_rtcp_nack_payload *)ast_data_buffer_remove(rtp->recv_buffer, rtp->expectedrxseqno);
if (payload) {
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, payload->buf, payload->size, prev_seqno));
frame = ast_frdup(ast_rtp_interpret(instance, srtp, &addr, payload->buf, payload->size, prev_seqno, bundled));
if (frame) {
AST_LIST_INSERT_TAIL(&frames, frame, frame_list);
prev_seqno = rtp->expectedrxseqno;
@ -7982,7 +7986,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
* to be the last packet processed right now and it is also guaranteed that it will always return
* non-NULL.
*/
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno);
frame = ast_rtp_interpret(instance, srtp, &addr, read_area, res, prev_seqno, bundled);
AST_LIST_INSERT_TAIL(&frames, frame, frame_list);
rtp->expectedrxseqno = seqno + 1;
if (rtp->expectedrxseqno == SEQNO_CYCLE_OVER) {