FFmpeg/libavformat/rtmppkt.c
Andreas Rheinhardt 790f793844 avutil/common: Don't auto-include mem.h
There are lots of files that don't need it: The number of object
files that actually need it went down from 2011 to 884 here.

Keep it for external users in order to not cause breakages.

Also improve the other headers a bit while just at it.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2024-03-31 00:08:43 +01:00

726 lines
22 KiB
C

/*
* RTMP input format
* Copyright (c) 2009 Konstantin Shishkov
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/bytestream.h"
#include "libavutil/intfloat.h"
#include "libavutil/mem.h"
#include "rtmppkt.h"
#include "flv.h"
#include "url.h"
void ff_amf_write_bool(uint8_t **dst, int val)
{
bytestream_put_byte(dst, AMF_DATA_TYPE_BOOL);
bytestream_put_byte(dst, val);
}
void ff_amf_write_number(uint8_t **dst, double val)
{
bytestream_put_byte(dst, AMF_DATA_TYPE_NUMBER);
bytestream_put_be64(dst, av_double2int(val));
}
void ff_amf_write_array_start(uint8_t **dst, uint32_t length)
{
bytestream_put_byte(dst, AMF_DATA_TYPE_ARRAY);
bytestream_put_be32(dst, length);
}
void ff_amf_write_string(uint8_t **dst, const char *str)
{
bytestream_put_byte(dst, AMF_DATA_TYPE_STRING);
bytestream_put_be16(dst, strlen(str));
bytestream_put_buffer(dst, str, strlen(str));
}
void ff_amf_write_string2(uint8_t **dst, const char *str1, const char *str2)
{
int len1 = 0, len2 = 0;
if (str1)
len1 = strlen(str1);
if (str2)
len2 = strlen(str2);
bytestream_put_byte(dst, AMF_DATA_TYPE_STRING);
bytestream_put_be16(dst, len1 + len2);
bytestream_put_buffer(dst, str1, len1);
bytestream_put_buffer(dst, str2, len2);
}
void ff_amf_write_null(uint8_t **dst)
{
bytestream_put_byte(dst, AMF_DATA_TYPE_NULL);
}
void ff_amf_write_object_start(uint8_t **dst)
{
bytestream_put_byte(dst, AMF_DATA_TYPE_OBJECT);
}
void ff_amf_write_field_name(uint8_t **dst, const char *str)
{
bytestream_put_be16(dst, strlen(str));
bytestream_put_buffer(dst, str, strlen(str));
}
void ff_amf_write_object_end(uint8_t **dst)
{
/* first two bytes are field name length = 0,
* AMF object should end with it and end marker
*/
bytestream_put_be24(dst, AMF_DATA_TYPE_OBJECT_END);
}
int ff_amf_read_number(GetByteContext *bc, double *val)
{
uint64_t read;
if (bytestream2_get_byte(bc) != AMF_DATA_TYPE_NUMBER)
return AVERROR_INVALIDDATA;
read = bytestream2_get_be64(bc);
*val = av_int2double(read);
return 0;
}
int ff_amf_get_string(GetByteContext *bc, uint8_t *str,
int strsize, int *length)
{
int stringlen = 0;
int readsize;
stringlen = bytestream2_get_be16(bc);
if (stringlen + 1 > strsize)
return AVERROR(EINVAL);
readsize = bytestream2_get_buffer(bc, str, stringlen);
if (readsize != stringlen) {
av_log(NULL, AV_LOG_WARNING,
"Unable to read as many bytes as AMF string signaled\n");
}
str[readsize] = '\0';
*length = FFMIN(stringlen, readsize);
return 0;
}
int ff_amf_read_string(GetByteContext *bc, uint8_t *str,
int strsize, int *length)
{
if (bytestream2_get_byte(bc) != AMF_DATA_TYPE_STRING)
return AVERROR_INVALIDDATA;
return ff_amf_get_string(bc, str, strsize, length);
}
int ff_amf_read_null(GetByteContext *bc)
{
if (bytestream2_get_byte(bc) != AMF_DATA_TYPE_NULL)
return AVERROR_INVALIDDATA;
return 0;
}
int ff_rtmp_check_alloc_array(RTMPPacket **prev_pkt, int *nb_prev_pkt,
int channel)
{
int nb_alloc;
RTMPPacket *ptr;
if (channel < *nb_prev_pkt)
return 0;
nb_alloc = channel + 16;
// This can't use the av_reallocp family of functions, since we
// would need to free each element in the array before the array
// itself is freed.
ptr = av_realloc_array(*prev_pkt, nb_alloc, sizeof(**prev_pkt));
if (!ptr)
return AVERROR(ENOMEM);
memset(ptr + *nb_prev_pkt, 0, (nb_alloc - *nb_prev_pkt) * sizeof(*ptr));
*prev_pkt = ptr;
*nb_prev_pkt = nb_alloc;
return 0;
}
int ff_rtmp_packet_read(URLContext *h, RTMPPacket *p,
int chunk_size, RTMPPacket **prev_pkt, int *nb_prev_pkt)
{
uint8_t hdr;
if (ffurl_read(h, &hdr, 1) != 1)
return AVERROR(EIO);
return ff_rtmp_packet_read_internal(h, p, chunk_size, prev_pkt,
nb_prev_pkt, hdr);
}
static int rtmp_packet_read_one_chunk(URLContext *h, RTMPPacket *p,
int chunk_size, RTMPPacket **prev_pkt_ptr,
int *nb_prev_pkt, uint8_t hdr)
{
uint8_t buf[16];
int channel_id, timestamp, size;
uint32_t ts_field; // non-extended timestamp or delta field
uint32_t extra = 0;
enum RTMPPacketType type;
int written = 0;
int ret, toread;
RTMPPacket *prev_pkt;
written++;
channel_id = hdr & 0x3F;
if (channel_id < 2) { //special case for channel number >= 64
buf[1] = 0;
if (ffurl_read_complete(h, buf, channel_id + 1) != channel_id + 1)
return AVERROR(EIO);
written += channel_id + 1;
channel_id = AV_RL16(buf) + 64;
}
if ((ret = ff_rtmp_check_alloc_array(prev_pkt_ptr, nb_prev_pkt,
channel_id)) < 0)
return ret;
prev_pkt = *prev_pkt_ptr;
size = prev_pkt[channel_id].size;
type = prev_pkt[channel_id].type;
extra = prev_pkt[channel_id].extra;
hdr >>= 6; // header size indicator
if (hdr == RTMP_PS_ONEBYTE) {
ts_field = prev_pkt[channel_id].ts_field;
} else {
if (ffurl_read_complete(h, buf, 3) != 3)
return AVERROR(EIO);
written += 3;
ts_field = AV_RB24(buf);
if (hdr != RTMP_PS_FOURBYTES) {
if (ffurl_read_complete(h, buf, 3) != 3)
return AVERROR(EIO);
written += 3;
size = AV_RB24(buf);
if (ffurl_read_complete(h, buf, 1) != 1)
return AVERROR(EIO);
written++;
type = buf[0];
if (hdr == RTMP_PS_TWELVEBYTES) {
if (ffurl_read_complete(h, buf, 4) != 4)
return AVERROR(EIO);
written += 4;
extra = AV_RL32(buf);
}
}
}
if (ts_field == 0xFFFFFF) {
if (ffurl_read_complete(h, buf, 4) != 4)
return AVERROR(EIO);
timestamp = AV_RB32(buf);
} else {
timestamp = ts_field;
}
if (hdr != RTMP_PS_TWELVEBYTES)
timestamp += prev_pkt[channel_id].timestamp;
if (prev_pkt[channel_id].read && size != prev_pkt[channel_id].size) {
av_log(h, AV_LOG_ERROR, "RTMP packet size mismatch %d != %d\n",
size, prev_pkt[channel_id].size);
ff_rtmp_packet_destroy(&prev_pkt[channel_id]);
prev_pkt[channel_id].read = 0;
return AVERROR_INVALIDDATA;
}
if (!prev_pkt[channel_id].read) {
if ((ret = ff_rtmp_packet_create(p, channel_id, type, timestamp,
size)) < 0)
return ret;
p->read = written;
p->offset = 0;
prev_pkt[channel_id].ts_field = ts_field;
prev_pkt[channel_id].timestamp = timestamp;
} else {
// previous packet in this channel hasn't completed reading
RTMPPacket *prev = &prev_pkt[channel_id];
p->data = prev->data;
p->size = prev->size;
p->channel_id = prev->channel_id;
p->type = prev->type;
p->ts_field = prev->ts_field;
p->extra = prev->extra;
p->offset = prev->offset;
p->read = prev->read + written;
p->timestamp = prev->timestamp;
prev->data = NULL;
}
p->extra = extra;
// save history
prev_pkt[channel_id].channel_id = channel_id;
prev_pkt[channel_id].type = type;
prev_pkt[channel_id].size = size;
prev_pkt[channel_id].extra = extra;
size = size - p->offset;
toread = FFMIN(size, chunk_size);
if (ffurl_read_complete(h, p->data + p->offset, toread) != toread) {
ff_rtmp_packet_destroy(p);
return AVERROR(EIO);
}
size -= toread;
p->read += toread;
p->offset += toread;
if (size > 0) {
RTMPPacket *prev = &prev_pkt[channel_id];
prev->data = p->data;
prev->read = p->read;
prev->offset = p->offset;
p->data = NULL;
return AVERROR(EAGAIN);
}
prev_pkt[channel_id].read = 0; // read complete; reset if needed
return p->read;
}
int ff_rtmp_packet_read_internal(URLContext *h, RTMPPacket *p, int chunk_size,
RTMPPacket **prev_pkt, int *nb_prev_pkt,
uint8_t hdr)
{
while (1) {
int ret = rtmp_packet_read_one_chunk(h, p, chunk_size, prev_pkt,
nb_prev_pkt, hdr);
if (ret > 0 || ret != AVERROR(EAGAIN))
return ret;
if (ffurl_read(h, &hdr, 1) != 1)
return AVERROR(EIO);
}
}
int ff_rtmp_packet_write(URLContext *h, RTMPPacket *pkt,
int chunk_size, RTMPPacket **prev_pkt_ptr,
int *nb_prev_pkt)
{
uint8_t pkt_hdr[16], *p = pkt_hdr;
int mode = RTMP_PS_TWELVEBYTES;
int off = 0;
int written = 0;
int ret;
RTMPPacket *prev_pkt;
int use_delta; // flag if using timestamp delta, not RTMP_PS_TWELVEBYTES
uint32_t timestamp; // full 32-bit timestamp or delta value
if ((ret = ff_rtmp_check_alloc_array(prev_pkt_ptr, nb_prev_pkt,
pkt->channel_id)) < 0)
return ret;
prev_pkt = *prev_pkt_ptr;
//if channel_id = 0, this is first presentation of prev_pkt, send full hdr.
use_delta = prev_pkt[pkt->channel_id].channel_id &&
pkt->extra == prev_pkt[pkt->channel_id].extra &&
pkt->timestamp >= prev_pkt[pkt->channel_id].timestamp;
timestamp = pkt->timestamp;
if (use_delta) {
timestamp -= prev_pkt[pkt->channel_id].timestamp;
}
if (timestamp >= 0xFFFFFF) {
pkt->ts_field = 0xFFFFFF;
} else {
pkt->ts_field = timestamp;
}
if (use_delta) {
if (pkt->type == prev_pkt[pkt->channel_id].type &&
pkt->size == prev_pkt[pkt->channel_id].size) {
mode = RTMP_PS_FOURBYTES;
if (pkt->ts_field == prev_pkt[pkt->channel_id].ts_field)
mode = RTMP_PS_ONEBYTE;
} else {
mode = RTMP_PS_EIGHTBYTES;
}
}
if (pkt->channel_id < 64) {
bytestream_put_byte(&p, pkt->channel_id | (mode << 6));
} else if (pkt->channel_id < 64 + 256) {
bytestream_put_byte(&p, 0 | (mode << 6));
bytestream_put_byte(&p, pkt->channel_id - 64);
} else {
bytestream_put_byte(&p, 1 | (mode << 6));
bytestream_put_le16(&p, pkt->channel_id - 64);
}
if (mode != RTMP_PS_ONEBYTE) {
bytestream_put_be24(&p, pkt->ts_field);
if (mode != RTMP_PS_FOURBYTES) {
bytestream_put_be24(&p, pkt->size);
bytestream_put_byte(&p, pkt->type);
if (mode == RTMP_PS_TWELVEBYTES)
bytestream_put_le32(&p, pkt->extra);
}
}
if (pkt->ts_field == 0xFFFFFF)
bytestream_put_be32(&p, timestamp);
// save history
prev_pkt[pkt->channel_id].channel_id = pkt->channel_id;
prev_pkt[pkt->channel_id].type = pkt->type;
prev_pkt[pkt->channel_id].size = pkt->size;
prev_pkt[pkt->channel_id].timestamp = pkt->timestamp;
prev_pkt[pkt->channel_id].ts_field = pkt->ts_field;
prev_pkt[pkt->channel_id].extra = pkt->extra;
// FIXME:
// Writing packets is currently not optimized to minimize system calls.
// Since system calls flush on exit which we cannot change in a system-independant way.
// We should fix this behavior and by writing packets in a single or in as few as possible system calls.
// Protocols like TCP and RTMP should benefit from this when enabling TCP_NODELAY.
if ((ret = ffurl_write(h, pkt_hdr, p - pkt_hdr)) < 0)
return ret;
written = p - pkt_hdr + pkt->size;
while (off < pkt->size) {
int towrite = FFMIN(chunk_size, pkt->size - off);
if ((ret = ffurl_write(h, pkt->data + off, towrite)) < 0)
return ret;
off += towrite;
if (off < pkt->size) {
uint8_t marker = 0xC0 | pkt->channel_id;
if ((ret = ffurl_write(h, &marker, 1)) < 0)
return ret;
written++;
if (pkt->ts_field == 0xFFFFFF) {
uint8_t ts_header[4];
AV_WB32(ts_header, timestamp);
if ((ret = ffurl_write(h, ts_header, 4)) < 0)
return ret;
written += 4;
}
}
}
return written;
}
int ff_rtmp_packet_create(RTMPPacket *pkt, int channel_id, RTMPPacketType type,
int timestamp, int size)
{
if (size) {
pkt->data = av_realloc(NULL, size);
if (!pkt->data)
return AVERROR(ENOMEM);
}
pkt->size = size;
pkt->channel_id = channel_id;
pkt->type = type;
pkt->timestamp = timestamp;
pkt->extra = 0;
pkt->ts_field = 0;
return 0;
}
void ff_rtmp_packet_destroy(RTMPPacket *pkt)
{
if (!pkt)
return;
av_freep(&pkt->data);
pkt->size = 0;
}
static int amf_tag_skip(GetByteContext *gb)
{
AMFDataType type;
unsigned nb = -1;
int parse_key = 1;
if (bytestream2_get_bytes_left(gb) < 1)
return -1;
type = bytestream2_get_byte(gb);
switch (type) {
case AMF_DATA_TYPE_NUMBER:
bytestream2_get_be64(gb);
return 0;
case AMF_DATA_TYPE_BOOL:
bytestream2_get_byte(gb);
return 0;
case AMF_DATA_TYPE_STRING:
bytestream2_skip(gb, bytestream2_get_be16(gb));
return 0;
case AMF_DATA_TYPE_LONG_STRING:
bytestream2_skip(gb, bytestream2_get_be32(gb));
return 0;
case AMF_DATA_TYPE_NULL:
return 0;
case AMF_DATA_TYPE_DATE:
bytestream2_skip(gb, 10);
return 0;
case AMF_DATA_TYPE_ARRAY:
parse_key = 0;
case AMF_DATA_TYPE_MIXEDARRAY:
nb = bytestream2_get_be32(gb);
case AMF_DATA_TYPE_OBJECT:
while (nb-- > 0 || type != AMF_DATA_TYPE_ARRAY) {
int t;
if (parse_key) {
int size = bytestream2_get_be16(gb);
if (!size) {
bytestream2_get_byte(gb);
break;
}
if (size < 0 || size >= bytestream2_get_bytes_left(gb))
return -1;
bytestream2_skip(gb, size);
}
t = amf_tag_skip(gb);
if (t < 0 || bytestream2_get_bytes_left(gb) <= 0)
return -1;
}
return 0;
case AMF_DATA_TYPE_OBJECT_END: return 0;
default: return -1;
}
}
int ff_amf_tag_size(const uint8_t *data, const uint8_t *data_end)
{
GetByteContext gb;
int ret;
if (data >= data_end)
return -1;
bytestream2_init(&gb, data, data_end - data);
ret = amf_tag_skip(&gb);
if (ret < 0 || bytestream2_get_bytes_left(&gb) <= 0)
return -1;
av_assert0(bytestream2_tell(&gb) >= 0 && bytestream2_tell(&gb) <= data_end - data);
return bytestream2_tell(&gb);
}
static int amf_get_field_value2(GetByteContext *gb,
const uint8_t *name, uint8_t *dst, int dst_size)
{
int namelen = strlen(name);
int len;
while (bytestream2_peek_byte(gb) != AMF_DATA_TYPE_OBJECT && bytestream2_get_bytes_left(gb) > 0) {
int ret = amf_tag_skip(gb);
if (ret < 0)
return -1;
}
if (bytestream2_get_bytes_left(gb) < 3)
return -1;
bytestream2_get_byte(gb);
for (;;) {
int size = bytestream2_get_be16(gb);
if (!size)
break;
if (size < 0 || size >= bytestream2_get_bytes_left(gb))
return -1;
bytestream2_skip(gb, size);
if (size == namelen && !memcmp(gb->buffer-size, name, namelen)) {
switch (bytestream2_get_byte(gb)) {
case AMF_DATA_TYPE_NUMBER:
snprintf(dst, dst_size, "%g", av_int2double(bytestream2_get_be64(gb)));
break;
case AMF_DATA_TYPE_BOOL:
snprintf(dst, dst_size, "%s", bytestream2_get_byte(gb) ? "true" : "false");
break;
case AMF_DATA_TYPE_STRING:
len = bytestream2_get_be16(gb);
if (dst_size < 1)
return -1;
if (dst_size < len + 1)
len = dst_size - 1;
bytestream2_get_buffer(gb, dst, len);
dst[len] = 0;
break;
default:
return -1;
}
return 0;
}
len = amf_tag_skip(gb);
if (len < 0 || bytestream2_get_bytes_left(gb) <= 0)
return -1;
}
return -1;
}
int ff_amf_get_field_value(const uint8_t *data, const uint8_t *data_end,
const uint8_t *name, uint8_t *dst, int dst_size)
{
GetByteContext gb;
if (data >= data_end)
return -1;
bytestream2_init(&gb, data, data_end - data);
return amf_get_field_value2(&gb, name, dst, dst_size);
}
#ifdef DEBUG
static const char* rtmp_packet_type(int type)
{
switch (type) {
case RTMP_PT_CHUNK_SIZE: return "chunk size";
case RTMP_PT_BYTES_READ: return "bytes read";
case RTMP_PT_USER_CONTROL: return "user control";
case RTMP_PT_WINDOW_ACK_SIZE: return "window acknowledgement size";
case RTMP_PT_SET_PEER_BW: return "set peer bandwidth";
case RTMP_PT_AUDIO: return "audio packet";
case RTMP_PT_VIDEO: return "video packet";
case RTMP_PT_FLEX_STREAM: return "Flex shared stream";
case RTMP_PT_FLEX_OBJECT: return "Flex shared object";
case RTMP_PT_FLEX_MESSAGE: return "Flex shared message";
case RTMP_PT_NOTIFY: return "notification";
case RTMP_PT_SHARED_OBJ: return "shared object";
case RTMP_PT_INVOKE: return "invoke";
case RTMP_PT_METADATA: return "metadata";
default: return "unknown";
}
}
static void amf_tag_contents(void *ctx, const uint8_t *data,
const uint8_t *data_end)
{
unsigned int size, nb = -1;
char buf[1024];
AMFDataType type;
int parse_key = 1;
if (data >= data_end)
return;
switch ((type = *data++)) {
case AMF_DATA_TYPE_NUMBER:
av_log(ctx, AV_LOG_DEBUG, " number %g\n", av_int2double(AV_RB64(data)));
return;
case AMF_DATA_TYPE_BOOL:
av_log(ctx, AV_LOG_DEBUG, " bool %d\n", *data);
return;
case AMF_DATA_TYPE_STRING:
case AMF_DATA_TYPE_LONG_STRING:
if (type == AMF_DATA_TYPE_STRING) {
size = bytestream_get_be16(&data);
} else {
size = bytestream_get_be32(&data);
}
size = FFMIN(size, sizeof(buf) - 1);
memcpy(buf, data, size);
buf[size] = 0;
av_log(ctx, AV_LOG_DEBUG, " string '%s'\n", buf);
return;
case AMF_DATA_TYPE_NULL:
av_log(ctx, AV_LOG_DEBUG, " NULL\n");
return;
case AMF_DATA_TYPE_ARRAY:
parse_key = 0;
case AMF_DATA_TYPE_MIXEDARRAY:
nb = bytestream_get_be32(&data);
case AMF_DATA_TYPE_OBJECT:
av_log(ctx, AV_LOG_DEBUG, " {\n");
while (nb-- > 0 || type != AMF_DATA_TYPE_ARRAY) {
int t;
if (parse_key) {
size = bytestream_get_be16(&data);
size = FFMIN(size, sizeof(buf) - 1);
if (!size) {
av_log(ctx, AV_LOG_DEBUG, " }\n");
data++;
break;
}
memcpy(buf, data, size);
buf[size] = 0;
if (size >= data_end - data)
return;
data += size;
av_log(ctx, AV_LOG_DEBUG, " %s: ", buf);
}
amf_tag_contents(ctx, data, data_end);
t = ff_amf_tag_size(data, data_end);
if (t < 0 || t >= data_end - data)
return;
data += t;
}
return;
case AMF_DATA_TYPE_OBJECT_END:
av_log(ctx, AV_LOG_DEBUG, " }\n");
return;
default:
return;
}
}
void ff_rtmp_packet_dump(void *ctx, RTMPPacket *p)
{
av_log(ctx, AV_LOG_DEBUG, "RTMP packet type '%s'(%d) for channel %d, timestamp %d, extra field %d size %d\n",
rtmp_packet_type(p->type), p->type, p->channel_id, p->timestamp, p->extra, p->size);
if (p->type == RTMP_PT_INVOKE || p->type == RTMP_PT_NOTIFY) {
uint8_t *src = p->data, *src_end = p->data + p->size;
while (src < src_end) {
int sz;
amf_tag_contents(ctx, src, src_end);
sz = ff_amf_tag_size(src, src_end);
if (sz < 0)
break;
src += sz;
}
} else if (p->type == RTMP_PT_WINDOW_ACK_SIZE) {
av_log(ctx, AV_LOG_DEBUG, "Window acknowledgement size = %d\n", AV_RB32(p->data));
} else if (p->type == RTMP_PT_SET_PEER_BW) {
av_log(ctx, AV_LOG_DEBUG, "Set Peer BW = %d\n", AV_RB32(p->data));
} else if (p->type != RTMP_PT_AUDIO && p->type != RTMP_PT_VIDEO && p->type != RTMP_PT_METADATA) {
int i;
for (i = 0; i < p->size; i++)
av_log(ctx, AV_LOG_DEBUG, " %02X", p->data[i]);
av_log(ctx, AV_LOG_DEBUG, "\n");
}
}
#endif
int ff_amf_match_string(const uint8_t *data, int size, const char *str)
{
int len = strlen(str);
int amf_len, type;
if (size < 1)
return 0;
type = *data++;
if (type != AMF_DATA_TYPE_LONG_STRING &&
type != AMF_DATA_TYPE_STRING)
return 0;
if (type == AMF_DATA_TYPE_LONG_STRING) {
if ((size -= 4 + 1) < 0)
return 0;
amf_len = bytestream_get_be32(&data);
} else {
if ((size -= 2 + 1) < 0)
return 0;
amf_len = bytestream_get_be16(&data);
}
if (amf_len > size)
return 0;
if (amf_len != len)
return 0;
return !memcmp(data, str, len);
}