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