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Side by Side Diff: base/openssl_util.h

Issue 6805019: Move crypto files out of base, to a top level directory. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src/
Patch Set: Created 9 years, 8 months ago
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1 // Copyright (c) 2010 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 BASE_OPENSSL_UTIL_H_
6 #define BASE_OPENSSL_UTIL_H_
7 #pragma once
8
9 #include "base/basictypes.h"
10 #include "base/tracked.h"
11
12 namespace base {
13
14 // A helper class that takes care of destroying OpenSSL objects when it goes out
15 // of scope.
16 template <typename T, void (*destructor)(T*)>
17 class ScopedOpenSSL {
18 public:
19 ScopedOpenSSL() : ptr_(NULL) { }
20 explicit ScopedOpenSSL(T* ptr) : ptr_(ptr) { }
21 ~ScopedOpenSSL() {
22 reset(NULL);
23 }
24
25 T* get() const { return ptr_; }
26 void reset(T* ptr) {
27 if (ptr != ptr_) {
28 if (ptr_) (*destructor)(ptr_);
29 ptr_ = ptr;
30 }
31 }
32
33 private:
34 T* ptr_;
35
36 DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSL);
37 };
38
39 // Provides a buffer of at least MIN_SIZE bytes, for use when calling OpenSSL's
40 // SHA256, HMAC, etc functions, adapting the buffer sizing rules to meet those
41 // of the our base wrapper APIs.
42 // This allows the library to write directly to the caller's buffer if it is of
43 // sufficient size, but if not it will write to temporary |min_sized_buffer_|
44 // of required size and then its content is automatically copied out on
45 // destruction, with truncation as appropriate.
46 template<int MIN_SIZE>
47 class ScopedOpenSSLSafeSizeBuffer {
48 public:
49 ScopedOpenSSLSafeSizeBuffer(unsigned char* output, size_t output_len)
50 : output_(output),
51 output_len_(output_len) {
52 }
53
54 ~ScopedOpenSSLSafeSizeBuffer() {
55 if (output_len_ < MIN_SIZE) {
56 // Copy the temporary buffer out, truncating as needed.
57 memcpy(output_, min_sized_buffer_, output_len_);
58 }
59 // else... any writing already happened directly into |output_|.
60 }
61
62 unsigned char* safe_buffer() {
63 return output_len_ < MIN_SIZE ? min_sized_buffer_ : output_;
64 }
65
66 private:
67 // Pointer to the caller's data area and it's associated size, where data
68 // written via safe_buffer() will [eventually] end up.
69 unsigned char* output_;
70 size_t output_len_;
71
72 // Temporary buffer writen into in the case where the caller's
73 // buffer is not of sufficient size.
74 unsigned char min_sized_buffer_[MIN_SIZE];
75
76 DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSLSafeSizeBuffer);
77 };
78
79 // Initialize OpenSSL if it isn't already initialized. This must be called
80 // before any other OpenSSL functions.
81 // This function is thread-safe, and OpenSSL will only ever be initialized once.
82 // OpenSSL will be properly shut down on program exit.
83 void EnsureOpenSSLInit();
84
85 // Drains the OpenSSL ERR_get_error stack. On a debug build the error codes
86 // are send to VLOG(1), on a release build they are disregarded. In most
87 // cases you should pass FROM_HERE as the |location|.
88 void ClearOpenSSLERRStack(const tracked_objects::Location& location);
89
90 // Place an instance of this class on the call stack to automatically clear
91 // the OpenSSL error stack on function exit.
92 class OpenSSLErrStackTracer {
93 public:
94 // Pass FROM_HERE as |location|, to help track the source of OpenSSL error
95 // messages. Note any diagnostic emitted will be tagged with the location of
96 // the constructor call as it's not possible to trace a destructor's callsite.
97 explicit OpenSSLErrStackTracer(const tracked_objects::Location& location)
98 : location_(location) {
99 EnsureOpenSSLInit();
100 }
101 ~OpenSSLErrStackTracer() {
102 ClearOpenSSLERRStack(location_);
103 }
104
105 private:
106 const tracked_objects::Location location_;
107
108 DISALLOW_IMPLICIT_CONSTRUCTORS(OpenSSLErrStackTracer);
109 };
110
111 } // namespace base
112
113 #endif // BASE_OPENSSL_UTIL_H_
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