1 // 2 // Copyright (C) 2009 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 UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_ 18 #define UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_ 19 20 #include <openssl/sha.h> 21 #include <unistd.h> 22 23 #include <string> 24 #include <vector> 25 26 #include <base/logging.h> 27 #include <base/macros.h> 28 #include <brillo/secure_blob.h> 29 30 // Omaha uses base64 encoded SHA-256 as the hash. This class provides a simple 31 // wrapper around OpenSSL providing such a formatted hash of data passed in. 32 // The methods of this class must be called in a very specific order: First the 33 // ctor (of course), then 0 or more calls to Update(), then Finalize(), then 0 34 // or more calls to hash(). 35 36 namespace chromeos_update_engine { 37 38 class HashCalculator { 39 public: 40 HashCalculator(); 41 42 // Update is called with all of the data that should be hashed in order. 43 // Update will read |length| bytes of |data|. 44 // Returns true on success. 45 bool Update(const void* data, size_t length); 46 47 // Updates the hash with up to |length| bytes of data from |file|. If |length| 48 // is negative, reads in and updates with the whole file. Returns the number 49 // of bytes that the hash was updated with, or -1 on error. 50 off_t UpdateFile(const std::string& name, off_t length); 51 52 // Call Finalize() when all data has been passed in. This method tells 53 // OpenSSl that no more data will come in and base64 encodes the resulting 54 // hash. 55 // Returns true on success. 56 bool Finalize(); 57 58 // Gets the hash. Finalize() must have been called. 59 const std::string& hash() const { 60 DCHECK(!hash_.empty()) << "Call Finalize() first"; 61 return hash_; 62 } 63 64 const brillo::Blob& raw_hash() const { 65 DCHECK(!raw_hash_.empty()) << "Call Finalize() first"; 66 return raw_hash_; 67 } 68 69 // Gets the current hash context. Note that the string will contain binary 70 // data (including \0 characters). 71 std::string GetContext() const; 72 73 // Sets the current hash context. |context| must the string returned by a 74 // previous HashCalculator::GetContext method call. Returns true on success, 75 // and false otherwise. 76 bool SetContext(const std::string& context); 77 78 static bool RawHashOfBytes(const void* data, 79 size_t length, 80 brillo::Blob* out_hash); 81 static bool RawHashOfData(const brillo::Blob& data, 82 brillo::Blob* out_hash); 83 static off_t RawHashOfFile(const std::string& name, off_t length, 84 brillo::Blob* out_hash); 85 86 // Used by tests 87 static std::string HashOfBytes(const void* data, size_t length); 88 static std::string HashOfString(const std::string& str); 89 static std::string HashOfData(const brillo::Blob& data); 90 91 private: 92 // If non-empty, the final base64 encoded hash and the raw hash. Will only be 93 // set to non-empty when Finalize is called. 94 std::string hash_; 95 brillo::Blob raw_hash_; 96 97 // Init success 98 bool valid_; 99 100 // The hash state used by OpenSSL 101 SHA256_CTX ctx_; 102 DISALLOW_COPY_AND_ASSIGN(HashCalculator); 103 }; 104 105 } // namespace chromeos_update_engine 106 107 #endif // UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_ 108
