1 files changed, 289 insertions, 0 deletions
diff --git a/dom/media/eme/clearkey/ClearKeyDecryptionManager.cpp b/dom/media/eme/clearkey/ClearKeyDecryptionManager.cpp
new file mode 100644
index 0000000000..7eeca88985
--- /dev/null
+++ b/dom/media/eme/clearkey/ClearKeyDecryptionManager.cpp
@@ -0,0 +1,289 @@
+/*
+ * Copyright 2015, Mozilla Foundation and contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ClearKeyDecryptionManager.h"
+
+#include <assert.h>
+#include <string.h>
+
+#include <vector>
+#include <algorithm>
+
+#include "mozilla/CheckedInt.h"
+#include "mozilla/Span.h"
+#include "psshparser/PsshParser.h"
+
+using namespace cdm;
+
+bool AllZero(const std::vector<uint32_t>& aBytes) {
+  return all_of(aBytes.begin(), aBytes.end(),
+                [](uint32_t b) { return b == 0; });
+}
+
+class ClearKeyDecryptor : public RefCounted {
+ public:
+  ClearKeyDecryptor();
+
+  void InitKey(const Key& aKey);
+  bool HasKey() const { return !mKey.empty(); }
+
+  Status Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
+                 const CryptoMetaData& aMetadata);
+
+  const Key& DecryptionKey() const { return mKey; }
+
+ private:
+  ~ClearKeyDecryptor();
+
+  Key mKey;
+};
+
+/* static */
+ClearKeyDecryptionManager* ClearKeyDecryptionManager::sInstance = nullptr;
+
+/* static */
+ClearKeyDecryptionManager* ClearKeyDecryptionManager::Get() {
+  if (!sInstance) {
+    sInstance = new ClearKeyDecryptionManager();
+  }
+  return sInstance;
+}
+
+ClearKeyDecryptionManager::ClearKeyDecryptionManager() {
+  CK_LOGD("ClearKeyDecryptionManager::ClearKeyDecryptionManager");
+}
+
+ClearKeyDecryptionManager::~ClearKeyDecryptionManager() {
+  CK_LOGD("ClearKeyDecryptionManager::~ClearKeyDecryptionManager");
+
+  sInstance = nullptr;
+
+  for (auto it = mDecryptors.begin(); it != mDecryptors.end(); it++) {
+    it->second->Release();
+  }
+  mDecryptors.clear();
+}
+
+bool ClearKeyDecryptionManager::HasSeenKeyId(const KeyId& aKeyId) const {
+  CK_LOGD("ClearKeyDecryptionManager::SeenKeyId %s",
+          mDecryptors.find(aKeyId) != mDecryptors.end() ? "t" : "f");
+  return mDecryptors.find(aKeyId) != mDecryptors.end();
+}
+
+bool ClearKeyDecryptionManager::IsExpectingKeyForKeyId(
+    const KeyId& aKeyId) const {
+  CK_LOGARRAY("ClearKeyDecryptionManager::IsExpectingKeyForId ", aKeyId.data(),
+              aKeyId.size());
+  const auto& decryptor = mDecryptors.find(aKeyId);
+  return decryptor != mDecryptors.end() && !decryptor->second->HasKey();
+}
+
+bool ClearKeyDecryptionManager::HasKeyForKeyId(const KeyId& aKeyId) const {
+  CK_LOGD("ClearKeyDecryptionManager::HasKeyForKeyId");
+  const auto& decryptor = mDecryptors.find(aKeyId);
+  return decryptor != mDecryptors.end() && decryptor->second->HasKey();
+}
+
+const Key& ClearKeyDecryptionManager::GetDecryptionKey(const KeyId& aKeyId) {
+  assert(HasKeyForKeyId(aKeyId));
+  return mDecryptors[aKeyId]->DecryptionKey();
+}
+
+void ClearKeyDecryptionManager::InitKey(KeyId aKeyId, Key aKey) {
+  CK_LOGD("ClearKeyDecryptionManager::InitKey ", aKeyId.data(), aKeyId.size());
+  if (IsExpectingKeyForKeyId(aKeyId)) {
+    CK_LOGARRAY("Initialized Key ", aKeyId.data(), aKeyId.size());
+    mDecryptors[aKeyId]->InitKey(aKey);
+  } else {
+    CK_LOGARRAY("Failed to initialize key ", aKeyId.data(), aKeyId.size());
+  }
+}
+
+void ClearKeyDecryptionManager::ExpectKeyId(KeyId aKeyId) {
+  CK_LOGD("ClearKeyDecryptionManager::ExpectKeyId ", aKeyId.data(),
+          aKeyId.size());
+  if (!HasSeenKeyId(aKeyId)) {
+    mDecryptors[aKeyId] = new ClearKeyDecryptor();
+  }
+  mDecryptors[aKeyId]->AddRef();
+}
+
+void ClearKeyDecryptionManager::ReleaseKeyId(KeyId aKeyId) {
+  CK_LOGD("ClearKeyDecryptionManager::ReleaseKeyId");
+  assert(HasSeenKeyId(aKeyId));
+
+  ClearKeyDecryptor* decryptor = mDecryptors[aKeyId];
+  if (!decryptor->Release()) {
+    mDecryptors.erase(aKeyId);
+  }
+}
+
+Status ClearKeyDecryptionManager::Decrypt(std::vector<uint8_t>& aBuffer,
+                                          const CryptoMetaData& aMetadata) {
+  return Decrypt(&aBuffer[0], aBuffer.size(), aMetadata);
+}
+
+Status ClearKeyDecryptionManager::Decrypt(uint8_t* aBuffer,
+                                          uint32_t aBufferSize,
+                                          const CryptoMetaData& aMetadata) {
+  CK_LOGD("ClearKeyDecryptionManager::Decrypt");
+  if (!HasKeyForKeyId(aMetadata.mKeyId)) {
+    CK_LOGARRAY("Unable to find decryptor for keyId: ", aMetadata.mKeyId.data(),
+                aMetadata.mKeyId.size());
+    return Status::kNoKey;
+  }
+
+  CK_LOGARRAY("Found decryptor for keyId: ", aMetadata.mKeyId.data(),
+              aMetadata.mKeyId.size());
+  return mDecryptors[aMetadata.mKeyId]->Decrypt(aBuffer, aBufferSize,
+                                                aMetadata);
+}
+
+ClearKeyDecryptor::ClearKeyDecryptor() { CK_LOGD("ClearKeyDecryptor ctor"); }
+
+ClearKeyDecryptor::~ClearKeyDecryptor() {
+  if (HasKey()) {
+    CK_LOGARRAY("ClearKeyDecryptor dtor; key = ", mKey.data(), mKey.size());
+  } else {
+    CK_LOGD("ClearKeyDecryptor dtor");
+  }
+}
+
+void ClearKeyDecryptor::InitKey(const Key& aKey) { mKey = aKey; }
+
+Status ClearKeyDecryptor::Decrypt(uint8_t* aBuffer, uint32_t aBufferSize,
+                                  const CryptoMetaData& aMetadata) {
+  CK_LOGD("ClearKeyDecryptor::Decrypt");
+  // If the sample is split up into multiple encrypted subsamples, we need to
+  // stitch them into one continuous buffer for decryption.
+  std::vector<uint8_t> tmp(aBufferSize);
+  static_assert(sizeof(uintptr_t) == sizeof(uint8_t*),
+                "We need uintptr_t to be exactly the same size as a pointer");
+
+  // Decrypt CBCS case:
+  if (aMetadata.mEncryptionScheme == EncryptionScheme::kCbcs) {
+    mozilla::CheckedInt<uintptr_t> data = reinterpret_cast<uintptr_t>(aBuffer);
+    if (!data.isValid()) {
+      return Status::kDecryptError;
+    }
+    const uintptr_t endBuffer =
+        reinterpret_cast<uintptr_t>(aBuffer + aBufferSize);
+
+    if (aMetadata.NumSubsamples() == 0) {
+      if (data.value() > endBuffer) {
+        return Status::kDecryptError;
+      }
+      mozilla::Span<uint8_t> encryptedSpan =
+          mozilla::Span(reinterpret_cast<uint8_t*>(data.value()), aBufferSize);
+      if (!ClearKeyUtils::DecryptCbcs(mKey, aMetadata.mIV, encryptedSpan,
+                                      aMetadata.mCryptByteBlock,
+                                      aMetadata.mSkipByteBlock)) {
+        return Status::kDecryptError;
+      }
+      return Status::kSuccess;
+    }
+
+    for (size_t i = 0; i < aMetadata.NumSubsamples(); i++) {
+      data += aMetadata.mClearBytes[i];
+      if (!data.isValid() || data.value() > endBuffer) {
+        return Status::kDecryptError;
+      }
+      mozilla::CheckedInt<uintptr_t> dataAfterCipher =
+          data + aMetadata.mCipherBytes[i];
+      if (!dataAfterCipher.isValid() || dataAfterCipher.value() > endBuffer) {
+        // Trying to read past the end of the buffer!
+        return Status::kDecryptError;
+      }
+      mozilla::Span<uint8_t> encryptedSpan = mozilla::Span(
+          reinterpret_cast<uint8_t*>(data.value()), aMetadata.mCipherBytes[i]);
+      if (!ClearKeyUtils::DecryptCbcs(mKey, aMetadata.mIV, encryptedSpan,
+                                      aMetadata.mCryptByteBlock,
+                                      aMetadata.mSkipByteBlock)) {
+        return Status::kDecryptError;
+      }
+      data += aMetadata.mCipherBytes[i];
+      if (!data.isValid()) {
+        return Status::kDecryptError;
+      }
+    }
+    return Status::kSuccess;
+  }
+
+  // Decrypt CENC case:
+  if (aMetadata.NumSubsamples()) {
+    // Take all encrypted parts of subsamples and stitch them into one
+    // continuous encrypted buffer.
+    mozilla::CheckedInt<uintptr_t> data = reinterpret_cast<uintptr_t>(aBuffer);
+    const uintptr_t endBuffer =
+        reinterpret_cast<uintptr_t>(aBuffer + aBufferSize);
+    uint8_t* iter = &tmp[0];
+    for (size_t i = 0; i < aMetadata.NumSubsamples(); i++) {
+      data += aMetadata.mClearBytes[i];
+      if (!data.isValid() || data.value() > endBuffer) {
+        // Trying to read past the end of the buffer!
+        return Status::kDecryptError;
+      }
+      const uint32_t& cipherBytes = aMetadata.mCipherBytes[i];
+      mozilla::CheckedInt<uintptr_t> dataAfterCipher = data + cipherBytes;
+      if (!dataAfterCipher.isValid() || dataAfterCipher.value() > endBuffer) {
+        // Trying to read past the end of the buffer!
+        return Status::kDecryptError;
+      }
+
+      memcpy(iter, reinterpret_cast<uint8_t*>(data.value()), cipherBytes);
+
+      data = dataAfterCipher;
+      iter += cipherBytes;
+    }
+
+    tmp.resize((size_t)(iter - &tmp[0]));
+  } else {
+    memcpy(&tmp[0], aBuffer, aBufferSize);
+  }
+
+  // It is possible that we could be passed an unencrypted sample, if all
+  // encrypted sample lengths are zero, and in this case, a zero length
+  // IV is allowed.
+  assert(aMetadata.mIV.size() == 8 || aMetadata.mIV.size() == 16 ||
+         (aMetadata.mIV.empty() && AllZero(aMetadata.mCipherBytes)));
+
+  std::vector<uint8_t> iv(aMetadata.mIV);
+  iv.insert(iv.end(), CENC_KEY_LEN - aMetadata.mIV.size(), 0);
+
+  if (!ClearKeyUtils::DecryptAES(mKey, tmp, iv)) {
+    return Status::kDecryptError;
+  }
+
+  if (aMetadata.NumSubsamples()) {
+    // Take the decrypted buffer, split up into subsamples, and insert those
+    // subsamples back into their original position in the original buffer.
+    uint8_t* data = aBuffer;
+    uint8_t* iter = &tmp[0];
+    for (size_t i = 0; i < aMetadata.NumSubsamples(); i++) {
+      data += aMetadata.mClearBytes[i];
+      uint32_t cipherBytes = aMetadata.mCipherBytes[i];
+
+      memcpy(data, iter, cipherBytes);
+
+      data += cipherBytes;
+      iter += cipherBytes;
+    }
+  } else {
+    memcpy(aBuffer, &tmp[0], aBufferSize);
+  }
+
+  return Status::kSuccess;
+}