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Commit b2451bb3 authored by Chong Zhang's avatar Chong Zhang
Browse files

MediaCas: re-send the first scrambled TS packet to decoder 

Currently, for scrambled streams that require secure decoder,
we descramble the first TS packet (which includes the PES header)
into the clear, and this TS packet is not descrambled again
at decoding time.

However, descramblers may not be able to descramble the bitstream
into clear buffers past the PES header portion. So we need to
assume that in the first pass, we can only get up to the PES
header portion, and at decoding time, this TS packet should be
descrambled again fully.

bug: 111271614
Test: CTS MediaCasTest; MediaDrmClearKeyTest;
tested with clearkey cas plugin modified to return only the PES
header portion of the first TS packet, instead of the full TS.

Change-Id: I8e77df3c5fa1268282442b7556851d89918c244d
parent 84c05cdc

media/libstagefright/ACodecBufferChannel.cpp

+15 −2
Original line number Diff line number Diff line
@@ -129,6 +129,7 @@ status_t ACodecBufferChannel::queueSecureInputBuffer( 
        secureHandle = static_cast<native_handle_t *>(secureData->getDestinationPointer());

    }

    ssize_t result = -1;

    ssize_t codecDataOffset = 0;

    if (mCrypto != NULL) {

        ICrypto::DestinationBuffer destination;

        if (secure) {
@@ -180,9 +181,16 @@ status_t ACodecBufferChannel::queueSecureInputBuffer( 


        Status status = Status::OK;

        hidl_string detailedError;

        ScramblingControl sctrl = ScramblingControl::UNSCRAMBLED;



        if (key != NULL) {

            sctrl = (ScramblingControl)key[0];

            // Adjust for the PES offset

            codecDataOffset = key[2] | (key[3] << 8);

        }



        auto returnVoid = mDescrambler->descramble(

                key != NULL ? (ScramblingControl)key[0] : ScramblingControl::UNSCRAMBLED,

                sctrl,

                hidlSubSamples,

                srcBuffer,

                0,
@@ -202,6 +210,11 @@ status_t ACodecBufferChannel::queueSecureInputBuffer( 
            return UNKNOWN_ERROR;

        }



        if (result < codecDataOffset) {

            ALOGD("invalid codec data offset: %zd, result %zd", codecDataOffset, result);

            return BAD_VALUE;

        }



        ALOGV("descramble succeeded, %zd bytes", result);



        if (dstBuffer.type == BufferType::SHARED_MEMORY) {
@@ -210,7 +223,7 @@ status_t ACodecBufferChannel::queueSecureInputBuffer( 
        }

    }



    it->mCodecBuffer->setRange(0, result);

    it->mCodecBuffer->setRange(codecDataOffset, result - codecDataOffset);



    // Copy metadata from client to codec buffer.

    it->mCodecBuffer->meta()->clear();

media/libstagefright/mpeg2ts/ATSParser.cpp

+26 −10
Original line number Diff line number Diff line
@@ -1437,7 +1437,7 @@ status_t ATSParser::Stream::flushScrambled(SyncEvent *event) { 
    // Perform the 1st pass descrambling if needed

    if (descrambleBytes > 0) {

        memcpy(mDescrambledBuffer->data(), mBuffer->data(), descrambleBytes);

        mDescrambledBuffer->setRange(0, descrambleBytes);

        mDescrambledBuffer->setRange(0, mBuffer->size());



        hidl_vec<SubSample> subSamples;

        subSamples.resize(descrambleSubSamples);
@@ -1454,10 +1454,9 @@ status_t ATSParser::Stream::flushScrambled(SyncEvent *event) { 
            }

        }



        uint64_t srcOffset = 0, dstOffset = 0;

        // If scrambled at PES-level, PES header should be skipped

        // If scrambled at PES-level, PES header is in the clear

        if (pesScramblingControl != 0) {

            srcOffset = dstOffset = pesOffset;

            subSamples[0].numBytesOfClearData = pesOffset;

            subSamples[0].numBytesOfEncryptedData -= pesOffset;

        }
@@ -1473,9 +1472,9 @@ status_t ATSParser::Stream::flushScrambled(SyncEvent *event) { 
                (ScramblingControl) sctrl,

                subSamples,

                mDescramblerSrcBuffer,

                srcOffset,

                0 /*srcOffset*/,

                dstBuffer,

                dstOffset,

                0 /*dstOffset*/,

                [&status, &bytesWritten, &detailedError] (

                        Status _status, uint32_t _bytesWritten,

                        const hidl_string& _detailedError) {
@@ -1492,9 +1491,15 @@ status_t ATSParser::Stream::flushScrambled(SyncEvent *event) { 


        ALOGV("[stream %d] descramble succeeded, %d bytes",

                mElementaryPID, bytesWritten);

        memcpy(mBuffer->data(), mDescrambledBuffer->data(), descrambleBytes);



        // Set descrambleBytes to the returned result.

        // Note that this might be smaller than the total length of input data.

        // (eg. when we're descrambling the PES header portion of a secure stream,

        // the plugin might cut it off right after the PES header.)

        descrambleBytes = bytesWritten;

    }



    sp<ABuffer> buffer;

    if (mQueue->isScrambled()) {

        // Queue subSample info for scrambled queue

        sp<ABuffer> clearSizesBuffer = new ABuffer(mSubSamples.size() * 4);
@@ -1506,8 +1511,7 @@ status_t ATSParser::Stream::flushScrambled(SyncEvent *event) { 
        for (auto it = mSubSamples.begin();

                it != mSubSamples.end(); it++, i++) {

            if ((it->transport_scrambling_mode == 0

                    && pesScramblingControl == 0)

                    || i < descrambleSubSamples) {

                    && pesScramblingControl == 0)) {

                clearSizePtr[i] = it->subSampleSize;

                encSizePtr[i] = 0;

            } else {
@@ -1516,14 +1520,26 @@ status_t ATSParser::Stream::flushScrambled(SyncEvent *event) { 
            }

            isSync |= it->random_access_indicator;

        }



        // If scrambled at PES-level, PES header is in the clear

        if (pesScramblingControl != 0) {

            clearSizePtr[0] = pesOffset;

            encSizePtr[0] -= pesOffset;

        }

        // Pass the original TS subsample size now. The PES header adjust

        // will be applied when the scrambled AU is dequeued.

        mQueue->appendScrambledData(

                mBuffer->data(), mBuffer->size(), sctrl,

                isSync, clearSizesBuffer, encSizesBuffer);



        buffer = mDescrambledBuffer;

    } else {

        memcpy(mBuffer->data(), mDescrambledBuffer->data(), descrambleBytes);



        buffer = mBuffer;

    }



    ABitReader br(mBuffer->data(), mBuffer->size());

    ABitReader br(buffer->data(), buffer->size());

    status_t err = parsePES(&br, event);



    if (err != OK) {

media/libstagefright/mpeg2ts/AnotherPacketSource.cpp

+8 −0
Original line number Diff line number Diff line
@@ -226,6 +226,7 @@ status_t AnotherPacketSource::read( 
        int32_t cryptoMode;

        if (buffer->meta()->findInt32("cryptoMode", &cryptoMode)) {

            int32_t cryptoKey;

            int32_t pesOffset;

            sp<ABuffer> clearBytesBuffer, encBytesBuffer;



            CHECK(buffer->meta()->findInt32("cryptoKey", &cryptoKey));
@@ -233,6 +234,8 @@ status_t AnotherPacketSource::read( 
                    && clearBytesBuffer != NULL);

            CHECK(buffer->meta()->findBuffer("encBytes", &encBytesBuffer)

                    && encBytesBuffer != NULL);

            CHECK(buffer->meta()->findInt32("pesOffset", &pesOffset)

                    && (pesOffset >= 0) && (pesOffset < 65536));



            bufmeta.setInt32(kKeyCryptoMode, cryptoMode);
@@ -240,6 +243,11 @@ status_t AnotherPacketSource::read( 
            bufmeta.setData(kKeyCryptoIV, 0, array, 16);



            array[0] = (uint8_t) (cryptoKey & 0xff);

            // array[1] contains PES header flag, which we don't use.

            // array[2~3] contain the PES offset.

            array[2] = (uint8_t) (pesOffset & 0xff);

            array[3] = (uint8_t) ((pesOffset >> 8) & 0xff);



            bufmeta.setData(kKeyCryptoKey, 0, array, 16);



            bufmeta.setData(kKeyPlainSizes, 0,

media/libstagefright/mpeg2ts/ESQueue.cpp

+3 −18
Original line number Diff line number Diff line
@@ -691,25 +691,9 @@ sp<ABuffer> ElementaryStreamQueue::dequeueScrambledAccessUnit() { 
        return NULL;

    }



    // skip the PES header, and copy the rest into scrambled access unit

    // copy into scrambled access unit

    sp<ABuffer> scrambledAccessUnit = ABuffer::CreateAsCopy(

            mScrambledBuffer->data() + pesOffset,

            scrambledLength - pesOffset);



    // fix up first sample size after skipping the PES header

    if (pesOffset > 0) {

        int32_t &firstClearSize = *(int32_t*)clearSizes->data();

        int32_t &firstEncSize = *(int32_t*)encSizes->data();

        // Cut away the PES header

        if (firstClearSize >= pesOffset) {

            // This is for TS-level scrambling, we descrambled the first

            // (or it was clear to begin with)

            firstClearSize -= pesOffset;

        } else if (firstEncSize >= pesOffset) {

            // This can only be PES-level scrambling

            firstEncSize -= pesOffset;

        }

    }

            mScrambledBuffer->data(), scrambledLength);



    scrambledAccessUnit->meta()->setInt64("timeUs", timeUs);

    if (isSync) {
@@ -723,6 +707,7 @@ sp<ABuffer> ElementaryStreamQueue::dequeueScrambledAccessUnit() { 
    scrambledAccessUnit->meta()->setInt32("cryptoKey", keyId);

    scrambledAccessUnit->meta()->setBuffer("clearBytes", clearSizes);

    scrambledAccessUnit->meta()->setBuffer("encBytes", encSizes);

    scrambledAccessUnit->meta()->setInt32("pesOffset", pesOffset);



    memmove(mScrambledBuffer->data(),

            mScrambledBuffer->data() + scrambledLength,