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