| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CRYPTO_OPENSSL_UTIL_H_ |
| #define CRYPTO_OPENSSL_UTIL_H_ |
| |
| #include <stddef.h> |
| #include <string.h> |
| |
| #include "base/location.h" |
| #include "base/macros.h" |
| #include "crypto/crypto_export.h" |
| |
| namespace crypto { |
| |
| // Provides a buffer of at least MIN_SIZE bytes, for use when calling OpenSSL's |
| // SHA256, HMAC, etc functions, adapting the buffer sizing rules to meet those |
| // of our base wrapper APIs. |
| // This allows the library to write directly to the caller's buffer if it is of |
| // sufficient size, but if not it will write to temporary |min_sized_buffer_| |
| // of required size and then its content is automatically copied out on |
| // destruction, with truncation as appropriate. |
| template<int MIN_SIZE> |
| class ScopedOpenSSLSafeSizeBuffer { |
| public: |
| ScopedOpenSSLSafeSizeBuffer(unsigned char* output, size_t output_len) |
| : output_(output), |
| output_len_(output_len) { |
| } |
| |
| ~ScopedOpenSSLSafeSizeBuffer() { |
| if (output_len_ < MIN_SIZE) { |
| // Copy the temporary buffer out, truncating as needed. |
| memcpy(output_, min_sized_buffer_, output_len_); |
| } |
| // else... any writing already happened directly into |output_|. |
| } |
| |
| unsigned char* safe_buffer() { |
| return output_len_ < MIN_SIZE ? min_sized_buffer_ : output_; |
| } |
| |
| private: |
| // Pointer to the caller's data area and its associated size, where data |
| // written via safe_buffer() will [eventually] end up. |
| unsigned char* output_; |
| size_t output_len_; |
| |
| // Temporary buffer writen into in the case where the caller's |
| // buffer is not of sufficient size. |
| unsigned char min_sized_buffer_[MIN_SIZE]; |
| |
| DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSLSafeSizeBuffer); |
| }; |
| |
| // Initialize OpenSSL if it isn't already initialized. This must be called |
| // before any other OpenSSL functions though it is safe and cheap to call this |
| // multiple times. |
| // This function is thread-safe, and OpenSSL will only ever be initialized once. |
| // OpenSSL will be properly shut down on program exit. |
| CRYPTO_EXPORT void EnsureOpenSSLInit(); |
| |
| // Drains the OpenSSL ERR_get_error stack. On a debug build the error codes |
| // are send to VLOG(1), on a release build they are disregarded. In most |
| // cases you should pass FROM_HERE as the |location|. |
| CRYPTO_EXPORT void ClearOpenSSLERRStack(const base::Location& location); |
| |
| // Place an instance of this class on the call stack to automatically clear |
| // the OpenSSL error stack on function exit. |
| class OpenSSLErrStackTracer { |
| public: |
| // Pass FROM_HERE as |location|, to help track the source of OpenSSL error |
| // messages. Note any diagnostic emitted will be tagged with the location of |
| // the constructor call as it's not possible to trace a destructor's callsite. |
| explicit OpenSSLErrStackTracer(const base::Location& location) |
| : location_(location) { |
| EnsureOpenSSLInit(); |
| } |
| ~OpenSSLErrStackTracer() { |
| ClearOpenSSLERRStack(location_); |
| } |
| |
| private: |
| const base::Location location_; |
| |
| DISALLOW_IMPLICIT_CONSTRUCTORS(OpenSSLErrStackTracer); |
| }; |
| |
| } // namespace crypto |
| |
| #endif // CRYPTO_OPENSSL_UTIL_H_ |