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.
5 #ifndef CRYPTO_OPENSSL_UTIL_H_
6 #define CRYPTO_OPENSSL_UTIL_H_
8 #include "base/basictypes.h"
9 #include "base/location.h"
10 #include "crypto/crypto_export.h"
14 // A helper class that takes care of destroying OpenSSL objects when they go out
16 template <typename T, void (*destructor)(T*)>
19 ScopedOpenSSL() : ptr_(NULL) { }
20 explicit ScopedOpenSSL(T* ptr) : ptr_(ptr) { }
25 T* get() const { return ptr_; }
33 if (ptr_) (*destructor)(ptr_);
41 DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSL);
44 // Provides a buffer of at least MIN_SIZE bytes, for use when calling OpenSSL's
45 // SHA256, HMAC, etc functions, adapting the buffer sizing rules to meet those
46 // of the our base wrapper APIs.
47 // This allows the library to write directly to the caller's buffer if it is of
48 // sufficient size, but if not it will write to temporary |min_sized_buffer_|
49 // of required size and then its content is automatically copied out on
50 // destruction, with truncation as appropriate.
51 template<int MIN_SIZE>
52 class ScopedOpenSSLSafeSizeBuffer {
54 ScopedOpenSSLSafeSizeBuffer(unsigned char* output, size_t output_len)
56 output_len_(output_len) {
59 ~ScopedOpenSSLSafeSizeBuffer() {
60 if (output_len_ < MIN_SIZE) {
61 // Copy the temporary buffer out, truncating as needed.
62 memcpy(output_, min_sized_buffer_, output_len_);
64 // else... any writing already happened directly into |output_|.
67 unsigned char* safe_buffer() {
68 return output_len_ < MIN_SIZE ? min_sized_buffer_ : output_;
72 // Pointer to the caller's data area and its associated size, where data
73 // written via safe_buffer() will [eventually] end up.
74 unsigned char* output_;
77 // Temporary buffer writen into in the case where the caller's
78 // buffer is not of sufficient size.
79 unsigned char min_sized_buffer_[MIN_SIZE];
81 DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSLSafeSizeBuffer);
84 // Initialize OpenSSL if it isn't already initialized. This must be called
85 // before any other OpenSSL functions.
86 // This function is thread-safe, and OpenSSL will only ever be initialized once.
87 // OpenSSL will be properly shut down on program exit.
88 void CRYPTO_EXPORT EnsureOpenSSLInit();
90 // Drains the OpenSSL ERR_get_error stack. On a debug build the error codes
91 // are send to VLOG(1), on a release build they are disregarded. In most
92 // cases you should pass FROM_HERE as the |location|.
93 void CRYPTO_EXPORT ClearOpenSSLERRStack(
94 const tracked_objects::Location& location);
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 {
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.
103 explicit OpenSSLErrStackTracer(const tracked_objects::Location& location)
104 : location_(location) {
107 ~OpenSSLErrStackTracer() {
108 ClearOpenSSLERRStack(location_);
112 const tracked_objects::Location location_;
114 DISALLOW_IMPLICIT_CONSTRUCTORS(OpenSSLErrStackTracer);
117 } // namespace crypto
119 #endif // CRYPTO_OPENSSL_UTIL_H_