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/**
* @file rtpext.c RTP Header Extensions
*
* Copyright (C) 2017 Creytiv.com
*/
#include <string.h>
#include <re.h>
#include <baresip.h>
#include "core.h"
/*
* RFC 5285 A General Mechanism for RTP Header Extensions
*
* - One-Byte Header: Supported
* - Two-Byte Header: Not supported
*/
int rtpext_hdr_encode(struct mbuf *mb, size_t num_bytes)
{
int err = 0;
if (!mb || !num_bytes)
return EINVAL;
if (num_bytes & 0x3) {
warning("rtpext: hdr_encode: num_bytes (%zu) must be multiple"
" of 4\n", num_bytes);
return EINVAL;
}
err |= mbuf_write_u16(mb, htons(RTPEXT_TYPE_MAGIC));
err |= mbuf_write_u16(mb, htons(num_bytes / 4));
return err;
}
int rtpext_encode(struct mbuf *mb, unsigned id, unsigned len,
const uint8_t *data)
{
size_t start;
int err;
if (!mb || !data)
return EINVAL;
if (id < RTPEXT_ID_MIN || id > RTPEXT_ID_MAX)
return EINVAL;
if (len < RTPEXT_LEN_MIN || len > RTPEXT_LEN_MAX)
return EINVAL;
start = mb->pos;
err = mbuf_write_u8(mb, id << 4 | (len-1));
err |= mbuf_write_mem(mb, data, len);
if (err)
return err;
/* padding */
while ((mb->pos - start) & 0x03)
err |= mbuf_write_u8(mb, 0x00);
return err;
}
int rtpext_decode(struct rtpext *ext, struct mbuf *mb)
{
uint8_t v;
int err;
if (!ext || !mb)
return EINVAL;
if (mbuf_get_left(mb) < 1)
return EBADMSG;
memset(ext, 0, sizeof(*ext));
v = mbuf_read_u8(mb);
ext->id = v >> 4;
ext->len = (v & 0x0f) + 1;
if (ext->id < RTPEXT_ID_MIN || ext->id > RTPEXT_ID_MAX) {
warning("rtpext: invalid ID %u\n", ext->id);
return EBADMSG;
}
if (ext->len > mbuf_get_left(mb)) {
warning("rtpext: short read\n");
return ENODATA;
}
err = mbuf_read_mem(mb, ext->data, ext->len);
if (err)
return err;
/* skip padding */
while (mbuf_get_left(mb)) {
uint8_t pad = mbuf_buf(mb)[0];
if (pad != 0x00)
break;
mbuf_advance(mb, 1);
}
return 0;
}
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