Bug 1487416 - Read pattern information in Sinf parser. r=jya

Differential Revision: https://phabricator.services.mozilla.com/D15873

--HG--
extra : moz-landing-system : lando

dom/media/mp4/SinfParser.cpp

@@ -55,12 +55,40 @@ Result<Ok, nsresult> SinfParser::ParseTenc(Box& aBox) {
     return Err(NS_ERROR_FAILURE);
   }
 
-  MOZ_TRY(reader->ReadU32());  // flags -- ignore
+  uint32_t flags;
+  MOZ_TRY_VAR(flags, reader->ReadU32());
+  uint8_t version = flags >> 24;
 
-  uint32_t isEncrypted;
-  MOZ_TRY_VAR(isEncrypted, reader->ReadU24());
+  // 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();
 }
 

dom/media/mp4/SinfParser.h

@@ -15,16 +15,25 @@ class Box;
 
 class Sinf : public Atom {
  public:
-  Sinf() : mDefaultIVSize(0), mDefaultEncryptionType() {}
+  Sinf()
+      : mDefaultIVSize(0),
+        mDefaultEncryptionType(),
+        mDefaultCryptByteBlock(0),
+        mDefaultSkipByteBlock(0) {}
   explicit Sinf(Box& aBox);
 
-  virtual bool IsValid() override {
-    return !!mDefaultIVSize && !!mDefaultEncryptionType;
+  bool IsValid() override {
+    return !!mDefaultEncryptionType &&  // Should have an encryption scheme
+           (mDefaultIVSize > 0 ||       // and either a default IV size
+            mDefaultConstantIV.Length() > 0);  // or a constant IV.
   }
 
   uint8_t mDefaultIVSize;
   AtomType mDefaultEncryptionType;
   uint8_t mDefaultKeyID[16];
+  uint8_t mDefaultCryptByteBlock;
+  uint8_t mDefaultSkipByteBlock;
+  nsTArray<uint8_t> mDefaultConstantIV;
 };
 
 class SinfParser {