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More robust checks for invalid MPEG frame headers.

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This commit is contained in:
Tsuda Kageyu 2015-12-08 11:11:50 +09:00
parent 847eec23cf
commit be9b5cc93a
4 changed files with 81 additions and 42 deletions
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79
taglib/mpeg/mpegheader.cpp
View File

@ -23,8 +23,6 @@
* http://www.mozilla.org/MPL/ *
***************************************************************************/
#include <bitset>
#include <tbytevector.h>
#include <tstring.h>
#include <tdebug.h>
@ -68,20 +66,21 @@ public:
// public members
////////////////////////////////////////////////////////////////////////////////
MPEG::Header::Header(const ByteVector &data)
MPEG::Header::Header(const ByteVector &data) :
d(new HeaderPrivate())
{
d = new HeaderPrivate;
parse(data);
}
MPEG::Header::Header(const Header &h) : d(h.d)
MPEG::Header::Header(const Header &h) :
d(h.d)
{
d->ref();
}
MPEG::Header::~Header()
{
if (d->deref())
if(d->deref())
delete d;
}
@ -164,39 +163,54 @@ MPEG::Header &MPEG::Header::operator=(const Header &h)
void MPEG::Header::parse(const ByteVector &data)
{
if(data.size() < 4 || static_cast<unsigned char>(data[0]) != 0xff) {
if(data.size() < 4) {
debug("MPEG::Header::parse() -- data is too short for an MPEG frame header.");
return;
}
// Check for the MPEG synch bytes.
if(static_cast<unsigned char>(data[0]) != 0xFF) {
debug("MPEG::Header::parse() -- First byte did not match MPEG synch.");
return;
}
std::bitset<32> flags(TAGLIB_CONSTRUCT_BITSET(data.toUInt()));
// Check for the second byte's part of the MPEG synch
if(!flags[23] || !flags[22] || !flags[21]) {
if((static_cast<unsigned char>(data[1]) & 0xE0) != 0xE0) {
debug("MPEG::Header::parse() -- Second byte did not match MPEG synch.");
return;
}
// Set the MPEG version
if(!flags[20] && !flags[19])
const int versionBits = (static_cast<unsigned char>(data[1]) >> 3) & 0x03;
if(versionBits == 0)
d->version = Version2_5;
else if(flags[20] && !flags[19])
else if(versionBits == 2)
d->version = Version2;
else if(flags[20] && flags[19])
else if(versionBits == 3)
d->version = Version1;
else {
debug("MPEG::Header::parse() -- Invalid MPEG version bits.");
return;
}
// Set the MPEG layer
if(!flags[18] && flags[17])
d->layer = 3;
else if(flags[18] && !flags[17])
d->layer = 2;
else if(flags[18] && flags[17])
d->layer = 1;
const int layerBits = (static_cast<unsigned char>(data[1]) >> 1) & 0x03;
d->protectionEnabled = !flags[16];
if(layerBits == 1)
d->layer = 3;
else if(layerBits == 2)
d->layer = 2;
else if(layerBits == 3)
d->layer = 1;
else {
debug("MPEG::Header::parse() -- Invalid MPEG layer bits.");
return;
}
d->protectionEnabled = (static_cast<unsigned char>(data[1] & 0x01) == 0);
// Set the bitrate
@ -219,9 +233,14 @@ void MPEG::Header::parse(const ByteVector &data)
// The bitrate index is encoded as the first 4 bits of the 3rd byte,
// i.e. 1111xxxx
int i = static_cast<unsigned char>(data[2]) >> 4;
const int bitrateIndex = (static_cast<unsigned char>(data[2]) >> 4) & 0x0F;
d->bitrate = bitrates[versionIndex][layerIndex][i];
d->bitrate = bitrates[versionIndex][layerIndex][bitrateIndex];
if(d->bitrate == 0) {
debug("MPEG::Header::parse() -- Invalid bit rate.");
return;
}
// Set the sample rate
@ -233,9 +252,9 @@ void MPEG::Header::parse(const ByteVector &data)
// The sample rate index is encoded as two bits in the 3nd byte, i.e. xxxx11xx
i = static_cast<unsigned char>(data[2]) >> 2 & 0x03;
const int samplerateIndex = (static_cast<unsigned char>(data[2]) >> 2) & 0x03;
d->sampleRate = sampleRates[d->version][i];
d->sampleRate = sampleRates[d->version][samplerateIndex];
if(d->sampleRate == 0) {
debug("MPEG::Header::parse() -- Invalid sample rate.");
@ -245,13 +264,13 @@ void MPEG::Header::parse(const ByteVector &data)
// The channel mode is encoded as a 2 bit value at the end of the 3nd byte,
// i.e. xxxxxx11
d->channelMode = static_cast<ChannelMode>((static_cast<unsigned char>(data[3]) & 0xC0) >> 6);
d->channelMode = static_cast<ChannelMode>((static_cast<unsigned char>(data[3]) >> 6) & 0x03);
// TODO: Add mode extension for completeness
d->isOriginal = flags[2];
d->isCopyrighted = flags[3];
d->isPadded = flags[9];
d->isOriginal = ((static_cast<unsigned char>(data[3]) & 0x04) != 0);
d->isCopyrighted = ((static_cast<unsigned char>(data[3]) & 0x08) != 0);
d->isPadded = ((static_cast<unsigned char>(data[2]) & 0x02) != 0);
// Samples per frame

30
taglib/mpeg/mpegproperties.cpp
View File

@ -155,27 +155,33 @@ bool MPEG::Properties::isOriginal() const
void MPEG::Properties::read(File *file)
{
// Only the first frame is required if we have a VBR header.
// Only the first valid frame is required if we have a VBR header.
const long first = file->firstFrameOffset();
if(first < 0) {
debug("MPEG::Properties::read() -- Could not find a valid first MPEG frame in the stream.");
long firstFrameOffset = file->firstFrameOffset();
if(firstFrameOffset < 0) {
debug("MPEG::Properties::read() -- Could not find an MPEG frame in the stream.");
return;
}
file->seek(first);
const Header firstHeader(file->readBlock(4));
file->seek(firstFrameOffset);
Header firstHeader(file->readBlock(4));
if(!firstHeader.isValid()) {
debug("MPEG::Properties::read() -- The first page header is invalid.");
return;
while(!firstHeader.isValid()) {
firstFrameOffset = file->nextFrameOffset(firstFrameOffset + 1);
if(firstFrameOffset < 0) {
debug("MPEG::Properties::read() -- Could not find a valid first MPEG frame in the stream.");
return;
}
file->seek(firstFrameOffset);
firstHeader = Header(file->readBlock(4));
}
// Check for a VBR header that will help us in gathering information about a
// VBR stream.
file->seek(first + 4);
d->xingHeader = new XingHeader(file->readBlock(firstHeader.frameLength() - 4));
file->seek(firstFrameOffset);
d->xingHeader = new XingHeader(file->readBlock(firstHeader.frameLength()));
if(!d->xingHeader->isValid()) {
delete d->xingHeader;
d->xingHeader = 0;
@ -201,7 +207,7 @@ void MPEG::Properties::read(File *file)
d->bitrate = firstHeader.bitrate();
long streamLength = file->length() - first;
long streamLength = file->length() - firstFrameOffset;
if(file->hasID3v1Tag())
streamLength -= 128;

BIN
tests/data/invalid-frames.mp3 Normal file
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Binary file not shown.

14
tests/test_mpeg.cpp
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@ -22,6 +22,7 @@ class TestMPEG : public CppUnit::TestFixture
CPPUNIT_TEST(testAudioPropertiesXingHeaderVBR);
CPPUNIT_TEST(testAudioPropertiesVBRIHeader);
CPPUNIT_TEST(testAudioPropertiesNoVBRHeaders);
CPPUNIT_TEST(testSkipInvalidFrames);
CPPUNIT_TEST(testVersion2DurationWithXingHeader);
CPPUNIT_TEST(testSaveID3v24);
CPPUNIT_TEST(testSaveID3v24WrongParam);
@ -102,6 +103,19 @@ public:
CPPUNIT_ASSERT_EQUAL(209, lastHeader.frameLength());
}
void testSkipInvalidFrames()
{
MPEG::File f(TEST_FILE_PATH_C("invalid-frames.mp3"));
CPPUNIT_ASSERT(f.audioProperties());
CPPUNIT_ASSERT_EQUAL(0, f.audioProperties()->length());
CPPUNIT_ASSERT_EQUAL(0, f.audioProperties()->lengthInSeconds());
CPPUNIT_ASSERT_EQUAL(393, f.audioProperties()->lengthInMilliseconds());
CPPUNIT_ASSERT_EQUAL(160, f.audioProperties()->bitrate());
CPPUNIT_ASSERT_EQUAL(2, f.audioProperties()->channels());
CPPUNIT_ASSERT_EQUAL(44100, f.audioProperties()->sampleRate());
CPPUNIT_ASSERT(!f.audioProperties()->xingHeader());
}
void testVersion2DurationWithXingHeader()
{
MPEG::File f(TEST_FILE_PATH_C("mpeg2.mp3"));