1 files changed, 200 insertions, 0 deletions
diff --git a/toolkit/components/mediasniffer/nsMediaSniffer.cpp b/toolkit/components/mediasniffer/nsMediaSniffer.cpp
new file mode 100644
index 000000000..29ba311e6
--- /dev/null
+++ b/toolkit/components/mediasniffer/nsMediaSniffer.cpp
@@ -0,0 +1,200 @@
+/* -*- 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 "nsMediaSniffer.h"
+#include "nsIHttpChannel.h"
+#include "nsString.h"
+#include "nsMimeTypes.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/ModuleUtils.h"
+#include "mp3sniff.h"
+#include "nestegg/nestegg.h"
+#include "FlacDemuxer.h"
+
+#include "nsIClassInfoImpl.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", "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);
+}
+
+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;
+  }
+
+  // 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;
+}