diff options
Diffstat (limited to 'libavformat')
| -rw-r--r-- | libavformat/westwood.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/libavformat/westwood.c b/libavformat/westwood.c index 268f2e71ee..5b06acbeb8 100644 --- a/libavformat/westwood.c +++ b/libavformat/westwood.c @@ -90,14 +90,14 @@ static int wsaud_probe(AVProbeData *p) /* Probabilistic content detection strategy: There is no file signature * so perform sanity checks on various header parameters: * 8000 <= sample rate (16 bits) <= 48000 ==> 40001 acceptable numbers + * flags <= 0x03 (2 LSBs are used) ==> 4 acceptable numbers * compression type (8 bits) = 1 or 99 ==> 2 acceptable numbers - * There is a total of 24 bits. The number space contains 2^24 = - * 16777216 numbers. There are 40001 * 2 = 80002 acceptable combinations - * of numbers. There is a 80002/16777216 = 0.48% chance of a false - * positive. + * first audio chunk signature (32 bits) ==> 1 acceptable number + * The number space contains 2^64 numbers. There are 40001 * 4 * 2 * 1 = + * 320008 acceptable number combinations. */ - if (p->buf_size < AUD_HEADER_SIZE) + if (p->buf_size < AUD_HEADER_SIZE + AUD_CHUNK_PREAMBLE_SIZE) return 0; /* check sample rate */ @@ -105,11 +105,20 @@ static int wsaud_probe(AVProbeData *p) if ((field < 8000) || (field > 48000)) return 0; + /* enforce the rule that the top 6 bits of this flags field are reserved (0); + * this might not be true, but enforce it until deemed unnecessary */ + if (p->buf[10] & 0xFC) + return 0; + /* note: only check for WS IMA (type 99) right now since there is no * support for type 1 */ if (p->buf[11] != 99) return 0; + /* read ahead to the first audio chunk and validate the first header signature */ + if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE) + return 0; + /* return 1/2 certainty since this file check is a little sketchy */ return AVPROBE_SCORE_MAX / 2; } |