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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef DESCRAMBLER_API_H_
     18 #define DESCRAMBLER_API_H_
     19 
     20 #include <media/stagefright/MediaErrors.h>
     21 #include <media/cas/CasAPI.h>
     22 
     23 namespace android {
     24 
     25 struct AString;
     26 struct DescramblerPlugin;
     27 
     28 struct DescramblerFactory {
     29     DescramblerFactory() {}
     30     virtual ~DescramblerFactory() {}
     31 
     32     // Determine if the plugin can handle the CA scheme identified by CA_system_id.
     33     virtual bool isSystemIdSupported(
     34             int32_t CA_system_id) const = 0;
     35 
     36     // Construct a new instance of a DescramblerPlugin given a CA_system_id
     37     virtual status_t createPlugin(
     38             int32_t CA_system_id, DescramblerPlugin **plugin) = 0;
     39 
     40 private:
     41     DescramblerFactory(const DescramblerFactory &);
     42     DescramblerFactory &operator=(const DescramblerFactory &);
     43 };
     44 
     45 struct DescramblerPlugin {
     46     enum ScramblingControl {
     47         kScrambling_Unscrambled = 0,
     48         kScrambling_Reserved    = 1,
     49         kScrambling_EvenKey     = 2,
     50         kScrambling_OddKey      = 3,
     51         kScrambling_Mask_Key    = 0x3,
     52 
     53         // Hint that the descrambling request is for a PES header only
     54         kScrambling_Flag_PesHeader = (1 << 31),
     55     };
     56 
     57     struct SubSample {
     58         uint32_t mNumBytesOfClearData;
     59         uint32_t mNumBytesOfEncryptedData;
     60     };
     61 
     62     DescramblerPlugin() {}
     63     virtual ~DescramblerPlugin() {}
     64 
     65     // If this method returns false, a non-secure decoder will be used to
     66     // decode the data after decryption. The decrypt API below will have
     67     // to support insecure decryption of the data (secure = false) for
     68     // media data of the given mime type.
     69     virtual bool requiresSecureDecoderComponent(const char *mime) const = 0;
     70 
     71     // A MediaCas session may be associated with a MediaCrypto session.  The
     72     // associated MediaCas session is used to load decryption keys
     73     // into the crypto/cas plugin.  The keys are then referenced by key-id
     74     // in the 'key' parameter to the decrypt() method.
     75     // Should return NO_ERROR on success, ERROR_DRM_SESSION_NOT_OPENED if
     76     // the session is not opened and a code from MediaErrors.h otherwise.
     77     virtual status_t setMediaCasSession(const CasSessionId& sessionId) = 0;
     78 
     79     // If the error returned falls into the range
     80     // ERROR_DRM_VENDOR_MIN..ERROR_DRM_VENDOR_MAX, errorDetailMsg should be
     81     // filled in with an appropriate string.
     82     // At the java level these special errors will then trigger a
     83     // MediaCodec.CryptoException that gives clients access to both
     84     // the error code and the errorDetailMsg.
     85     // Returns a non-negative result to indicate the number of bytes written
     86     // to the dstPtr, or a negative result to indicate an error.
     87     virtual ssize_t descramble(
     88             bool secure,
     89             ScramblingControl scramblingControl,
     90             size_t numSubSamples,
     91             const SubSample *subSamples,
     92             const void *srcPtr,
     93             int32_t srcOffset,
     94             void *dstPtr,
     95             int32_t dstOffset,
     96             AString *errorDetailMsg) = 0;
     97 
     98 private:
     99     DescramblerPlugin(const DescramblerPlugin &);
    100     DescramblerPlugin &operator=(const DescramblerPlugin &);
    101 };
    102 
    103 }  // namespace android
    104 
    105 extern "C" {
    106     extern android::DescramblerFactory *createDescramblerFactory();
    107 }
    108 
    109 #endif  // DESCRAMBLER_API_H_
    110