/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim:set ts=2 sw=2 sts=2 tw=80 et cindent: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "ADTSDemuxer.h"

#include "FlacDemuxer.h"

#include "mozilla/ArrayUtils.h"

#include "mozilla/ModuleUtils.h"

#include "mp3sniff.h"

#include "nestegg/nestegg.h"

#include "nsIClassInfoImpl.h"

#include "nsIHttpChannel.h"

#include "nsMediaSniffer.h"

#include "nsMimeTypes.h"

#include "nsString.h"

#include <algorithm>

// The minimum number of bytes that are needed to attempt to sniff an mp4 file.

static const unsigned MP4_MIN_BYTES_COUNT = 12;

// The maximum number of bytes to consider when attempting to sniff a file.

static const uint32_t MAX_BYTES_SNIFFED = 512;

// The maximum number of bytes to consider when attempting to sniff for a mp3

// bitstream.

// This is 320kbps * 144 / 32kHz + 1 padding byte + 4 bytes of capture pattern.

static const uint32_t MAX_BYTES_SNIFFED_MP3 = 320 * 144 / 32 + 1 + 4;

NS_IMPL_ISUPPORTS(nsMediaSniffer, nsIContentSniffer)

nsMediaSnifferEntry nsMediaSniffer::sSnifferEntries[] = {

  // The string OggS, followed by the null byte.

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF\xFF", "OggS", APPLICATION_OGG),

  // The string RIFF, followed by four bytes, followed by the string WAVE

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF\x00\x00\x00\x00\xFF\xFF\xFF\xFF", "RIFF\x00\x00\x00\x00WAVE", AUDIO_WAV),

  // mp3 with ID3 tags, the string "ID3".

  PATTERN_ENTRY("\xFF\xFF\xFF", "ID3", AUDIO_MP3),

  // FLAC with standard header

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "fLaC", AUDIO_FLAC)

};

// For a complete list of file types, see http://www.ftyps.com/index.html

nsMediaSnifferEntry sFtypEntries[] = {

  PATTERN_ENTRY("\xFF\xFF\xFF", "mp4", VIDEO_MP4), // Could be mp41 or mp42.

  PATTERN_ENTRY("\xFF\xFF\xFF", "avc", VIDEO_MP4), // Could be avc1, avc2, ...

  PATTERN_ENTRY("\xFF\xFF\xFF", "3gp", VIDEO_3GPP), // Could be 3gp4, 3gp5, ...

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4V ", VIDEO_MP4),

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4A ", AUDIO_MP4),

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4P ", AUDIO_MP4),

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "qt  ", VIDEO_QUICKTIME),

  PATTERN_ENTRY("\xFF\xFF\xFF", "iso", VIDEO_MP4), // Could be isom or iso2.

  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "mmp4", VIDEO_MP4),

};

static bool MatchesBrands(const uint8_t aData[4], nsACString& aSniffedType)

{

  for (size_t i = 0; i < mozilla::ArrayLength(sFtypEntries); ++i) {

    const auto& currentEntry = sFtypEntries[i];

    bool matched = true;

    MOZ_ASSERT(currentEntry.mLength <= 4,

               "Pattern is too large to match brand strings.");

    for (uint32_t j = 0; j < currentEntry.mLength; ++j) {

      if ((currentEntry.mMask[j] & aData[j]) != currentEntry.mPattern[j]) {

        matched = false;

        break;

      }

    }

    if (matched) {

      aSniffedType.AssignASCII(currentEntry.mContentType);

      return true;

    }

  }

  return false;

}

// This function implements sniffing algorithm for MP4 family file types,

// including MP4 (described at http://mimesniff.spec.whatwg.org/#signature-for-mp4),

// M4A (Apple iTunes audio), and 3GPP.

static bool

MatchesMP4(const uint8_t* aData, const uint32_t aLength,

           nsACString& aSniffedType)

{

  if (aLength <= MP4_MIN_BYTES_COUNT) {

    return false;

  }

  // Conversion from big endian to host byte order.

  uint32_t boxSize =

    (uint32_t)(aData[3] | aData[2] << 8 | aData[1] << 16 | aData[0] << 24);

  // Boxsize should be evenly divisible by 4.

  if (boxSize % 4 || aLength < boxSize) {

    return false;

  }

  // The string "ftyp".

  if (aData[4] != 0x66 ||

      aData[5] != 0x74 ||

      aData[6] != 0x79 ||

      aData[7] != 0x70) {

    return false;

  }

  if (MatchesBrands(&aData[8], aSniffedType)) {

    return true;

  }

  // Skip minor_version (bytes 12-15).

  uint32_t bytesRead = 16;

  while (bytesRead < boxSize) {

    if (MatchesBrands(&aData[bytesRead], aSniffedType)) {

      return true;

    }

    bytesRead += 4;

  }

  return false;

}

static bool MatchesWebM(const uint8_t* aData, const uint32_t aLength)

{

  return nestegg_sniff((uint8_t*)aData, aLength) ? true : false;

}

// This function implements mp3 sniffing based on parsing

// packet headers and looking for expected boundaries.

static bool MatchesMP3(const uint8_t* aData, const uint32_t aLength)

{

  return mp3_sniff(aData, (long)aLength);

}

static bool MatchesFLAC(const uint8_t* aData, const uint32_t aLength)

{

  return mozilla::FlacDemuxer::FlacSniffer(aData, aLength);

}

static bool MatchesADTS(const uint8_t* aData, const uint32_t aLength)

{

  return mozilla::ADTSDemuxer::ADTSSniffer(aData, aLength);

}

NS_IMETHODIMP

nsMediaSniffer::GetMIMETypeFromContent(nsIRequest* aRequest,

                                       const uint8_t* aData,

                                       const uint32_t aLength,

                                       nsACString& aSniffedType)

{

  nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);

  if (channel) {

    nsLoadFlags loadFlags = 0;

    channel->GetLoadFlags(&loadFlags);

    if (!(loadFlags & nsIChannel::LOAD_MEDIA_SNIFFER_OVERRIDES_CONTENT_TYPE)) {

      // For media, we want to sniff only if the Content-Type is unknown, or if

      // it is application/octet-stream.

      nsAutoCString contentType;

      nsresult rv = channel->GetContentType(contentType);

      NS_ENSURE_SUCCESS(rv, rv);

      if (!contentType.IsEmpty() &&

          !contentType.EqualsLiteral(APPLICATION_OCTET_STREAM) &&

          !contentType.EqualsLiteral(UNKNOWN_CONTENT_TYPE)) {

        return NS_ERROR_NOT_AVAILABLE;

      }

    }

  }

  const uint32_t clampedLength = std::min(aLength, MAX_BYTES_SNIFFED);

  for (size_t i = 0; i < mozilla::ArrayLength(sSnifferEntries); ++i) {

    const nsMediaSnifferEntry& currentEntry = sSnifferEntries[i];

    if (clampedLength < currentEntry.mLength || currentEntry.mLength == 0) {

      continue;

    }

    bool matched = true;

    for (uint32_t j = 0; j < currentEntry.mLength; ++j) {

      if ((currentEntry.mMask[j] & aData[j]) != currentEntry.mPattern[j]) {

        matched = false;

        break;

      }

    }

    if (matched) {

      aSniffedType.AssignASCII(currentEntry.mContentType);

      return NS_OK;

    }

  }

  if (MatchesMP4(aData, clampedLength, aSniffedType)) {

    return NS_OK;

  }

  if (MatchesWebM(aData, clampedLength)) {

    aSniffedType.AssignLiteral(VIDEO_WEBM);

    return NS_OK;

  }

  // Bug 950023: 512 bytes are often not enough to sniff for mp3.

  if (MatchesMP3(aData, std::min(aLength, MAX_BYTES_SNIFFED_MP3))) {

    aSniffedType.AssignLiteral(AUDIO_MP3);

    return NS_OK;

  }

  // Flac frames are generally big, often in excess of 24kB.

  // Using a size of MAX_BYTES_SNIFFED effectively means that we will only

  // recognize flac content if it starts with a frame.

  if (MatchesFLAC(aData, clampedLength)) {

    aSniffedType.AssignLiteral(AUDIO_FLAC);

    return NS_OK;

  }

  if (MatchesADTS(aData, clampedLength)) {

    aSniffedType.AssignLiteral(AUDIO_AAC);

    return NS_OK;

  }

  // Could not sniff the media type, we are required to set it to

  // application/octet-stream.

  aSniffedType.AssignLiteral(APPLICATION_OCTET_STREAM);

  return NS_ERROR_NOT_AVAILABLE;

}