/*M
\emph{Fill the RTP packet structure by unpacking payload
information.}
**/
int rtp_pkt_unpack(rtp_pkt_t *pkt) {
assert(pkt != NULL);
/* v: 2 bits, p: 1 bit, x: 1 bit, cc: 4 bits */
pkt->b.v = (pkt->data[0] >> 6) & 0x3;
/* check version */
if (pkt->b.v != 2)
return 0;
pkt->b.p = (pkt->data[0] >> 5) & 0x1;
pkt->b.x = (pkt->data[0] >> 4) & 0x1;
pkt->b.cc = (pkt->data[0]) & 0xf;
/* m: 1 bit, pt: 7 bits */
pkt->b.m = (pkt->data[1] >> 7) & 0x1;
pkt->b.pt = (pkt->data[1]) & 0x7f;
unsigned char *ptr = pkt->data + 2;
/* seq: 16 bits */
pkt->b.seq = UINT16_UNPACK(ptr);
/* timestamp: 32 bits */
pkt->timestamp = UINT32_UNPACK(ptr);
/* ssrc: 32 bits, just ignore it */
ptr += 4;
if (pkt->unpack)
if (!pkt->unpack(pkt))
return 0;
/*M
If padding is used, then padding length is in last byte.
**/
if (pkt->b.p) {
unsigned char *plen = pkt->data + pkt->length - 1;
pkt->plen = *plen;
} else {
pkt->plen = 0;
}
/*M
Ignore rest of packet for now.
**/
pkt->length -= pkt->hlen + pkt->b.cc * RTP_CSRC_SIZE;
if (pkt->b.p)
pkt->length -= pkt->plen + 1;
return 1;
}
/* endian issues will bite us if we don't call uint32_unpack when
* reading numbers from the cdb file, so we do it here. */
static int read_uint32(int fd, uint32_t *n)
{
unsigned char buf[4];
ssize_t err;
if ( (err = read(fd, &buf, sizeof(*n))) == -1)
return -1;
else if (err == 0)
return 1;
else if (err < sizeof(buf)) {
/* Error: could not read a whole uint32_t */
errno = EIO; /* ENODATA not on FreeBSD */
return -1;
}
UINT32_UNPACK(buf, n);
return 0;
}
