Source release 16.2.0

oemcrypto/test/oec_decrypt_fallback_chain.h

@@ -0,0 +1,59 @@
+// Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine Master
+// License Agreement.
+
+#ifndef CDM_OEC_DECRYPT_FALLBACK_CHAIN_H_
+#define CDM_OEC_DECRYPT_FALLBACK_CHAIN_H_
+
+#include "OEMCryptoCENC.h"
+#include "disallow_copy_and_assign.h"
+
+namespace wvoec {
+
+// This class groups static methods relating to providing proper fallback
+// behavior when calling DecryptCENC in OEMCrypto v16. Outside code can leverage
+// this behavior by passing the samples to be decrypted to Decrypt(), which will
+// set off the chain of fallback functions as needed.
+//
+// The behavior of this class is pathological. For each block of data, it will
+// greedily try every possible way of passing data to OEMCrypto until one works.
+// In the order tried, the ways to send data are:
+//   1) Multiple Samples at once
+//   2) Individual Samples one at a time
+//   3) Individual Subsamples one at a time
+//   4) Individual Half-Subsamples one at a time
+// On a device that only accepts half-subsamples, the way OEMCrypto v15 did,
+// this results in many needless roundtrips to OEMCrypto. This would be
+// inefficient behavior for a real CDM, but for the sake of testing, we want to
+// use the maximal way the OEMCrypto implementation will accept the data. And,
+// for implementations that do not accept multiple samples or subsamples per
+// call, we want to test that they correctly reject larger calls.
+class DecryptFallbackChain {
+ public:
+  static OEMCryptoResult Decrypt(
+      OEMCrypto_SESSION session_id, const OEMCrypto_SampleDescription* samples,
+      size_t samples_length, OEMCryptoCipherMode cipher_mode,
+      const OEMCrypto_CENCEncryptPatternDesc* pattern);
+
+ private:
+  static OEMCryptoResult DecryptSample(
+      OEMCrypto_SESSION session_id, const OEMCrypto_SampleDescription& sample,
+      OEMCryptoCipherMode cipher_mode,
+      const OEMCrypto_CENCEncryptPatternDesc* pattern);
+
+  static OEMCryptoResult DecryptSubsample(
+      OEMCrypto_SESSION session_id, const OEMCrypto_SampleDescription& sample,
+      const OEMCrypto_CENCEncryptPatternDesc* pattern);
+
+  static OEMCryptoResult DecryptSubsampleHalf(
+      OEMCrypto_SESSION session_id, const OEMCrypto_SampleDescription& sample,
+      const OEMCrypto_CENCEncryptPatternDesc* pattern);
+
+  // There is no reason to have an instance of this class.
+  DecryptFallbackChain() = delete;
+  CORE_DISALLOW_COPY_AND_ASSIGN(DecryptFallbackChain);
+};
+
+}  // namespace wvoec
+
+#endif  // CDM_OEC_DECRYPT_FALLBACK_CHAIN_H_