1 files changed, 95 insertions, 0 deletions
diff --git a/dom/media/mp4/SinfParser.cpp b/dom/media/mp4/SinfParser.cpp
new file mode 100644
index 0000000000..4ea14adaaa
--- /dev/null
+++ b/dom/media/mp4/SinfParser.cpp
@@ -0,0 +1,95 @@
+/* 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 "mozilla/Unused.h"
+#include "SinfParser.h"
+#include "AtomType.h"
+#include "Box.h"
+#include "ByteStream.h"
+
+namespace mozilla {
+
+Sinf::Sinf(Box& aBox) : mDefaultIVSize(0), mDefaultEncryptionType() {
+  SinfParser parser(aBox);
+  if (parser.GetSinf().IsValid()) {
+    *this = parser.GetSinf();
+  }
+}
+
+SinfParser::SinfParser(Box& aBox) {
+  for (Box box = aBox.FirstChild(); box.IsAvailable(); box = box.Next()) {
+    if (box.IsType("schm")) {
+      mozilla::Unused << ParseSchm(box);
+    } else if (box.IsType("schi")) {
+      mozilla::Unused << ParseSchi(box);
+    }
+  }
+}
+
+Result<Ok, nsresult> SinfParser::ParseSchm(Box& aBox) {
+  BoxReader reader(aBox);
+
+  if (reader->Remaining() < 8) {
+    return Err(NS_ERROR_FAILURE);
+  }
+
+  MOZ_TRY(reader->ReadU32());  // flags -- ignore
+  MOZ_TRY_VAR(mSinf.mDefaultEncryptionType, reader->ReadU32());
+  return Ok();
+}
+
+Result<Ok, nsresult> SinfParser::ParseSchi(Box& aBox) {
+  for (Box box = aBox.FirstChild(); box.IsAvailable(); box = box.Next()) {
+    if (box.IsType("tenc") && ParseTenc(box).isErr()) {
+      return Err(NS_ERROR_FAILURE);
+    }
+  }
+  return Ok();
+}
+
+Result<Ok, nsresult> SinfParser::ParseTenc(Box& aBox) {
+  BoxReader reader(aBox);
+
+  if (reader->Remaining() < 24) {
+    return Err(NS_ERROR_FAILURE);
+  }
+
+  uint32_t flags;
+  MOZ_TRY_VAR(flags, reader->ReadU32());
+  uint8_t version = flags >> 24;
+
+  // Skip reserved byte
+  MOZ_TRY(reader->ReadU8());
+  if (version >= 1) {
+    uint8_t pattern;
+    MOZ_TRY_VAR(pattern, reader->ReadU8());
+    mSinf.mDefaultCryptByteBlock = pattern >> 4;
+    mSinf.mDefaultSkipByteBlock = pattern & 0x0f;
+  } else {
+    // Reserved if version is less than 1
+    MOZ_TRY(reader->ReadU8());
+    mSinf.mDefaultCryptByteBlock = 0;
+    mSinf.mDefaultSkipByteBlock = 0;
+  }
+
+  uint8_t isEncrypted;
+  MOZ_TRY_VAR(isEncrypted, reader->ReadU8());
+  MOZ_TRY_VAR(mSinf.mDefaultIVSize, reader->ReadU8());
+  memcpy(mSinf.mDefaultKeyID, reader->Read(16), 16);
+
+  if (isEncrypted && mSinf.mDefaultIVSize == 0) {
+    uint8_t defaultConstantIVSize;
+    MOZ_TRY_VAR(defaultConstantIVSize, reader->ReadU8());
+    if (!mSinf.mDefaultConstantIV.SetLength(defaultConstantIVSize,
+                                            mozilla::fallible)) {
+      return Err(NS_ERROR_FAILURE);
+    }
+    for (uint8_t i = 0; i < defaultConstantIVSize; i++) {
+      MOZ_TRY_VAR(mSinf.mDefaultConstantIV.ElementAt(i), reader->ReadU8());
+    }
+  }
+  return Ok();
+}
+
+}  // namespace mozilla