Alex Vakulenko | f602473 | 2016-01-22 16:52:43 -0800 | [diff] [blame^] | 1 | // Copyright (c) 2012 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 CRYPTO_OPENSSL_UTIL_H_ |
| 6 | #define CRYPTO_OPENSSL_UTIL_H_ |
| 7 | |
| 8 | #include "base/basictypes.h" |
| 9 | #include "base/location.h" |
| 10 | #include "crypto/crypto_export.h" |
| 11 | |
| 12 | namespace crypto { |
| 13 | |
| 14 | // Provides a buffer of at least MIN_SIZE bytes, for use when calling OpenSSL's |
| 15 | // SHA256, HMAC, etc functions, adapting the buffer sizing rules to meet those |
| 16 | // of the our base wrapper APIs. |
| 17 | // This allows the library to write directly to the caller's buffer if it is of |
| 18 | // sufficient size, but if not it will write to temporary |min_sized_buffer_| |
| 19 | // of required size and then its content is automatically copied out on |
| 20 | // destruction, with truncation as appropriate. |
| 21 | template<int MIN_SIZE> |
| 22 | class ScopedOpenSSLSafeSizeBuffer { |
| 23 | public: |
| 24 | ScopedOpenSSLSafeSizeBuffer(unsigned char* output, size_t output_len) |
| 25 | : output_(output), |
| 26 | output_len_(output_len) { |
| 27 | } |
| 28 | |
| 29 | ~ScopedOpenSSLSafeSizeBuffer() { |
| 30 | if (output_len_ < MIN_SIZE) { |
| 31 | // Copy the temporary buffer out, truncating as needed. |
| 32 | memcpy(output_, min_sized_buffer_, output_len_); |
| 33 | } |
| 34 | // else... any writing already happened directly into |output_|. |
| 35 | } |
| 36 | |
| 37 | unsigned char* safe_buffer() { |
| 38 | return output_len_ < MIN_SIZE ? min_sized_buffer_ : output_; |
| 39 | } |
| 40 | |
| 41 | private: |
| 42 | // Pointer to the caller's data area and its associated size, where data |
| 43 | // written via safe_buffer() will [eventually] end up. |
| 44 | unsigned char* output_; |
| 45 | size_t output_len_; |
| 46 | |
| 47 | // Temporary buffer writen into in the case where the caller's |
| 48 | // buffer is not of sufficient size. |
| 49 | unsigned char min_sized_buffer_[MIN_SIZE]; |
| 50 | |
| 51 | DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSLSafeSizeBuffer); |
| 52 | }; |
| 53 | |
| 54 | // Initialize OpenSSL if it isn't already initialized. This must be called |
| 55 | // before any other OpenSSL functions though it is safe and cheap to call this |
| 56 | // multiple times. |
| 57 | // This function is thread-safe, and OpenSSL will only ever be initialized once. |
| 58 | // OpenSSL will be properly shut down on program exit. |
| 59 | void CRYPTO_EXPORT EnsureOpenSSLInit(); |
| 60 | |
| 61 | // Drains the OpenSSL ERR_get_error stack. On a debug build the error codes |
| 62 | // are send to VLOG(1), on a release build they are disregarded. In most |
| 63 | // cases you should pass FROM_HERE as the |location|. |
| 64 | void CRYPTO_EXPORT ClearOpenSSLERRStack( |
| 65 | const tracked_objects::Location& location); |
| 66 | |
| 67 | // Place an instance of this class on the call stack to automatically clear |
| 68 | // the OpenSSL error stack on function exit. |
| 69 | class OpenSSLErrStackTracer { |
| 70 | public: |
| 71 | // Pass FROM_HERE as |location|, to help track the source of OpenSSL error |
| 72 | // messages. Note any diagnostic emitted will be tagged with the location of |
| 73 | // the constructor call as it's not possible to trace a destructor's callsite. |
| 74 | explicit OpenSSLErrStackTracer(const tracked_objects::Location& location) |
| 75 | : location_(location) { |
| 76 | EnsureOpenSSLInit(); |
| 77 | } |
| 78 | ~OpenSSLErrStackTracer() { |
| 79 | ClearOpenSSLERRStack(location_); |
| 80 | } |
| 81 | |
| 82 | private: |
| 83 | const tracked_objects::Location location_; |
| 84 | |
| 85 | DISALLOW_IMPLICIT_CONSTRUCTORS(OpenSSLErrStackTracer); |
| 86 | }; |
| 87 | |
| 88 | } // namespace crypto |
| 89 | |
| 90 | #endif // CRYPTO_OPENSSL_UTIL_H_ |