1 // Copyright (c) 2010 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_OPENSSL_UTIL_H_ 6 #define BASE_OPENSSL_UTIL_H_ 7 #pragma once 8 9 #include "base/basictypes.h" 10 #include "base/compiler_specific.h" 11 #include "base/tracked.h" 12 13 namespace base { 14 15 // A helper class that takes care of destroying OpenSSL objects when it goes out 16 // of scope. 17 template <typename T, void (*destructor)(T*)> 18 class ScopedOpenSSL { 19 public: ScopedOpenSSL()20 ScopedOpenSSL() : ptr_(NULL) { } ScopedOpenSSL(T * ptr)21 explicit ScopedOpenSSL(T* ptr) : ptr_(ptr) { } ~ScopedOpenSSL()22 ~ScopedOpenSSL() { 23 reset(NULL); 24 } 25 get()26 T* get() const { return ptr_; } reset(T * ptr)27 void reset(T* ptr) { 28 if (ptr != ptr_) { 29 if (ptr_) (*destructor)(ptr_); 30 ptr_ = ptr; 31 } 32 } release()33 T* release() WARN_UNUSED_RESULT { 34 T* result = ptr_; 35 ptr_ = NULL; 36 return result; 37 } 38 39 private: 40 T* ptr_; 41 42 DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSL); 43 }; 44 45 // Provides a buffer of at least MIN_SIZE bytes, for use when calling OpenSSL's 46 // SHA256, HMAC, etc functions, adapting the buffer sizing rules to meet those 47 // of the our base wrapper APIs. 48 // This allows the library to write directly to the caller's buffer if it is of 49 // sufficient size, but if not it will write to temporary |min_sized_buffer_| 50 // of required size and then its content is automatically copied out on 51 // destruction, with truncation as appropriate. 52 template<int MIN_SIZE> 53 class ScopedOpenSSLSafeSizeBuffer { 54 public: ScopedOpenSSLSafeSizeBuffer(unsigned char * output,size_t output_len)55 ScopedOpenSSLSafeSizeBuffer(unsigned char* output, size_t output_len) 56 : output_(output), 57 output_len_(output_len) { 58 } 59 ~ScopedOpenSSLSafeSizeBuffer()60 ~ScopedOpenSSLSafeSizeBuffer() { 61 if (output_len_ < MIN_SIZE) { 62 // Copy the temporary buffer out, truncating as needed. 63 memcpy(output_, min_sized_buffer_, output_len_); 64 } 65 // else... any writing already happened directly into |output_|. 66 } 67 safe_buffer()68 unsigned char* safe_buffer() { 69 return output_len_ < MIN_SIZE ? min_sized_buffer_ : output_; 70 } 71 72 private: 73 // Pointer to the caller's data area and it's associated size, where data 74 // written via safe_buffer() will [eventually] end up. 75 unsigned char* output_; 76 size_t output_len_; 77 78 // Temporary buffer writen into in the case where the caller's 79 // buffer is not of sufficient size. 80 unsigned char min_sized_buffer_[MIN_SIZE]; 81 82 DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSLSafeSizeBuffer); 83 }; 84 85 // Initialize OpenSSL if it isn't already initialized. This must be called 86 // before any other OpenSSL functions. 87 // This function is thread-safe, and OpenSSL will only ever be initialized once. 88 // OpenSSL will be properly shut down on program exit. 89 void EnsureOpenSSLInit(); 90 91 // Drains the OpenSSL ERR_get_error stack. On a debug build the error codes 92 // are send to VLOG(1), on a release build they are disregarded. In most 93 // cases you should pass FROM_HERE as the |location|. 94 void ClearOpenSSLERRStack(const tracked_objects::Location& location); 95 96 // Place an instance of this class on the call stack to automatically clear 97 // the OpenSSL error stack on function exit. 98 class OpenSSLErrStackTracer { 99 public: 100 // Pass FROM_HERE as |location|, to help track the source of OpenSSL error 101 // messages. Note any diagnostic emitted will be tagged with the location of 102 // the constructor call as it's not possible to trace a destructor's callsite. OpenSSLErrStackTracer(const tracked_objects::Location & location)103 explicit OpenSSLErrStackTracer(const tracked_objects::Location& location) 104 : location_(location) { 105 EnsureOpenSSLInit(); 106 } ~OpenSSLErrStackTracer()107 ~OpenSSLErrStackTracer() { 108 ClearOpenSSLERRStack(location_); 109 } 110 111 private: 112 const tracked_objects::Location location_; 113 114 DISALLOW_IMPLICIT_CONSTRUCTORS(OpenSSLErrStackTracer); 115 }; 116 117 } // namespace base 118 119 #endif // BASE_OPENSSL_UTIL_H_ 120