1 files changed, 245 insertions, 0 deletions
diff --git a/toolkit/components/mediasniffer/nsMediaSniffer.cpp b/toolkit/components/mediasniffer/nsMediaSniffer.cpp
new file mode 100644
index 0000000000..b6752cb438
--- /dev/null
+++ b/toolkit/components/mediasniffer/nsMediaSniffer.cpp
@@ -0,0 +1,245 @@
+/* -*- 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 "mozilla/ArrayUtils.h"
+#include "mozilla/ModuleUtils.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/Telemetry.h"
+#include "mp3sniff.h"
+#include "nestegg/nestegg.h"
+#include "nsHttpChannel.h"
+#include "nsIClassInfoImpl.h"
+#include "nsIChannel.h"
+#include "nsMediaSniffer.h"
+#include "nsMimeTypes.h"
+#include "nsQueryObject.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;
+// Multi-channel low sample-rate AAC packets can be huge, have a higher maximum
+// size.
+static const uint32_t MAX_BYTES_SNIFFED_ADTS = 8096;
+
+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,
+    // followed by 8 bytes, followed by 0x0055, the codec identifier for mp3 in
+    // a RIFF container. This entry MUST be before the next one, which is
+    // assumed to be a WAV file containing PCM data.
+    PATTERN_ENTRY("\xFF\xFF\xFF\xFF"
+                  "\x00\x00\x00\x00"
+                  "\xFF\xFF\xFF\xFF"
+                  "\x00\x00\x00\x00"
+                  "\x00\x00\x00\x00"
+                  "\xFF\xFF",
+                  "RIFF"
+                  "\x00\x00\x00\x00"
+                  "WAVE"
+                  "\x00\x00\x00\x00"
+                  "\x00\x00\x00\x00"
+                  "\x55\x00",
+                  AUDIO_MP3),
+    // 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),
+    PATTERN_ENTRY("\xFF\xFF\xFF\xFF\xFF\xFF\xFF", "#EXTM3U",
+                  APPLICATION_MPEGURL)};
+
+using PatternLabel = mozilla::Telemetry::LABELS_MEDIA_SNIFFER_MP4_BRAND_PATTERN;
+
+struct nsMediaSnifferFtypEntry : nsMediaSnifferEntry {
+  nsMediaSnifferFtypEntry(nsMediaSnifferEntry aBase, const PatternLabel aLabel)
+      : nsMediaSnifferEntry(aBase), mLabel(aLabel) {}
+  PatternLabel mLabel;
+};
+
+// For a complete list of file types, see http://www.ftyps.com/index.html
+nsMediaSnifferFtypEntry sFtypEntries[] = {
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "mp4", VIDEO_MP4),
+     PatternLabel::ftyp_mp4},  // Could be mp41 or mp42.
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "avc", VIDEO_MP4),
+     PatternLabel::ftyp_avc},  // Could be avc1, avc2, ...
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "3gp4", VIDEO_MP4),
+     PatternLabel::ftyp_3gp4},  // 3gp4 is based on MP4
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "3gp", VIDEO_3GPP),
+     PatternLabel::ftyp_3gp},  // Could be 3gp5, ...
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "M4V", VIDEO_MP4), PatternLabel::ftyp_M4V},
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "M4A", AUDIO_MP4), PatternLabel::ftyp_M4A},
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "M4P", AUDIO_MP4), PatternLabel::ftyp_M4P},
+    {PATTERN_ENTRY("\xFF\xFF", "qt", VIDEO_QUICKTIME), PatternLabel::ftyp_qt},
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "crx", APPLICATION_OCTET_STREAM),
+     PatternLabel::ftyp_crx},
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "iso", VIDEO_MP4),
+     PatternLabel::ftyp_iso},  // Could be isom or iso2.
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "mmp4", VIDEO_MP4),
+     PatternLabel::ftyp_mmp4},
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "avif", IMAGE_AVIF),
+     PatternLabel::ftyp_avif},
+};
+
+static bool MatchesBrands(const uint8_t aData[4], nsACString& aSniffedType) {
+  for (const auto& currentEntry : sFtypEntries) {
+    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) {
+      // If we eventually remove the "iso" pattern entry per bug 1725190,
+      // this block should be removed and the bug1725190.cr3 test in
+      // test_mediasniffer_ext.js will need to be updated
+      if (!mozilla::StaticPrefs::media_mp4_sniff_iso_brand() &&
+          currentEntry.mLabel == PatternLabel::ftyp_iso) {
+        continue;
+      }
+
+      aSniffedType.AssignASCII(currentEntry.mContentType);
+      AccumulateCategorical(currentEntry.mLabel);
+      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.
+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);
+}
+
+// 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 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) {
+  const uint32_t clampedLength = std::min(aLength, MAX_BYTES_SNIFFED);
+
+  auto maybeUpdate = mozilla::MakeScopeExit([request = RefPtr{aRequest}]() {
+    nsCOMPtr<nsIChannel> channel = do_QueryInterface(request);
+    if (channel && XRE_IsParentProcess()) {
+      if (RefPtr<mozilla::net::nsHttpChannel> httpChannel =
+              do_QueryObject(channel)) {
+        // If the audio or video type pattern matching algorithm given bytes
+        // does not return undefined, then disable the further check and allow
+        // the response.
+        httpChannel->DisableIsOpaqueResponseAllowedAfterSniffCheck(
+            mozilla::net::nsHttpChannel::SnifferType::Media);
+      }
+    };
+  });
+
+  for (const auto& currentEntry : sSnifferEntries) {
+    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;
+  }
+
+  if (MatchesADTS(aData, std::min(aLength, MAX_BYTES_SNIFFED_ADTS))) {
+    aSniffedType.AssignLiteral(AUDIO_AAC);
+    return NS_OK;
+  }
+
+  maybeUpdate.release();
+
+  // 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;
+}