/*
* NAME: tag->parse()
* DESCRIPTION: parse a complete ID3 tag
*/
struct id3_tag *id3_tag_parse(id3_byte_t const *data, id3_length_t length)
{
id3_byte_t const *ptr;
unsigned int version;
int flags;
id3_length_t size;
switch (tagtype(data, length)) {
case TAGTYPE_ID3V1:
return (length < 128) ? 0 : v1_parse(data);
case TAGTYPE_ID3V2:
break;
case TAGTYPE_ID3V2_FOOTER:
case TAGTYPE_NONE:
return 0;
}
/* ID3v2.x */
ptr = data;
parse_header(&ptr, &version, &flags, &size);
switch (ID3_TAG_VERSION_MAJOR(version)) {
case 4:
if (flags & ID3_TAG_FLAG_FOOTERPRESENT)
size += 10;
case 2:
case 3:
return (length < 10 + size) ? 0 : v2_parse(data);
}
return 0;
}
static
struct id3_tag *v2_parse(id3_byte_t const *ptr)
{
struct id3_tag *tag;
id3_byte_t *mem = 0;
tag = id3_tag_new();
if (tag) {
id3_byte_t const *end;
id3_length_t size;
parse_header(&ptr, &tag->version, &tag->flags, &size);
tag->paddedsize = 10 + size;
if ((tag->flags & ID3_TAG_FLAG_UNSYNCHRONISATION) &&
ID3_TAG_VERSION_MAJOR(tag->version) < 4) {
mem = malloc(size);
if (mem == 0)
goto fail;
memcpy(mem, ptr, size);
size = id3_util_deunsynchronise(mem, size);
ptr = mem;
}
end = ptr + size;
if (tag->flags & ID3_TAG_FLAG_EXTENDEDHEADER) {
switch (ID3_TAG_VERSION_MAJOR(tag->version)) {
case 2:
goto fail;
case 3:
{
id3_byte_t const *ehptr, *ehend;
id3_length_t ehsize;
enum {
EH_FLAG_CRC = 0x8000 /* CRC data present */
};
if (end - ptr < 4)
goto fail;
ehsize = id3_parse_uint(&ptr, 4);
if (ehsize > end - ptr)
goto fail;
ehptr = ptr;
ehend = ptr + ehsize;
ptr = ehend;
if (ehend - ehptr >= 6) {
int ehflags;
id3_length_t padsize;
ehflags = id3_parse_uint(&ehptr, 2);
padsize = id3_parse_uint(&ehptr, 4);
if (padsize > end - ptr)
goto fail;
end -= padsize;
if (ehflags & EH_FLAG_CRC) {
unsigned long crc;
if (ehend - ehptr < 4)
goto fail;
crc = id3_parse_uint(&ehptr, 4);
if (crc != id3_crc_compute(ptr, end - ptr))
goto fail;
tag->extendedflags |= ID3_TAG_EXTENDEDFLAG_CRCDATAPRESENT;
}
}
}
break;
case 4:
{
id3_byte_t const *ehptr, *ehend;
id3_length_t ehsize;
unsigned int bytes;
if (end - ptr < 4)
goto fail;
ehptr = ptr;
ehsize = id3_parse_syncsafe(&ptr, 4);
if (ehsize < 6 || ehsize > end - ehptr)
goto fail;
ehend = ehptr + ehsize;
bytes = id3_parse_uint(&ptr, 1);
if (bytes < 1 || bytes > ehend - ptr)
goto fail;
ehptr = ptr + bytes;
/* verify extended header size */
{
id3_byte_t const *flagsptr = ptr, *dataptr = ehptr;
unsigned int datalen;
int ehflags;
while (bytes--) {
for (ehflags = id3_parse_uint(&flagsptr, 1); ehflags;
ehflags = (ehflags << 1) & 0xff) {
if (ehflags & 0x80) {
if (dataptr == ehend)
goto fail;
datalen = id3_parse_uint(&dataptr, 1);
if (datalen > 0x7f || datalen > ehend - dataptr)
goto fail;
dataptr += datalen;
}
}
}
}
tag->extendedflags = id3_parse_uint(&ptr, 1);
ptr = ehend;
if (tag->extendedflags & ID3_TAG_EXTENDEDFLAG_TAGISANUPDATE) {
bytes = id3_parse_uint(&ehptr, 1);
ehptr += bytes;
}
if (tag->extendedflags & ID3_TAG_EXTENDEDFLAG_CRCDATAPRESENT) {
unsigned long crc;
bytes = id3_parse_uint(&ehptr, 1);
if (bytes < 5)
goto fail;
crc = id3_parse_syncsafe(&ehptr, 5);
ehptr += bytes - 5;
if (crc != id3_crc_compute(ptr, end - ptr))
goto fail;
}
if (tag->extendedflags & ID3_TAG_EXTENDEDFLAG_TAGRESTRICTIONS) {
bytes = id3_parse_uint(&ehptr, 1);
if (bytes < 1)
goto fail;
tag->restrictions = id3_parse_uint(&ehptr, 1);
ehptr += bytes - 1;
}
}
break;
}
}
/* frames */
while (ptr < end) {
struct id3_frame *frame;
if (*ptr == 0)
break; /* padding */
frame = id3_frame_parse(&ptr, end - ptr, tag->version);
if (frame == 0 || id3_tag_attachframe(tag, frame) == -1)
goto fail;
}
if (ID3_TAG_VERSION_MAJOR(tag->version) < 4 &&
id3_compat_fixup(tag) == -1)
goto fail;
}
if (0) {
fail:
id3_tag_delete(tag);
tag = 0;
}
if (mem)
free(mem);
return tag;
}
