Implement symmetric key for openssl

base/openssl_util.h

 // Copyright (c) 2010 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 BASE_OPENNSSL_UTIL_H_
-#define BASE_OPENNSSL_UTIL_H_
+#ifndef BASE_OPENSSL_UTIL_H_
+#define BASE_OPENSSL_UTIL_H_
 #pragma once
 
 #include "base/basictypes.h"
+#include "base/tracked.h"
 
 namespace base {
 
 // 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 the 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.
@@ skipping 19 matching lines @@
 
  private:
   // Pointer to the caller's data area and it's 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);
+};
+
+// 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.
+void ClearERRStack();

[wtc, 2010/11/11 23:39:15]

IMPORTANT: this function name should include "OpenSSL", since
this function is not in a namespace whose name indicates
OpenSSL.  This comment also applies to ScopedERRStackClearer.

[joth, 2010/11/12 12:15:53]

Done.

+
+// Put an instance of this class on the call stack to automatically clear the
+// OpenSSL error stack on exit of your function.
+class ScopedERRStackClearer {
+ public:
+  ScopedERRStackClearer() {}
+  ~ScopedERRStackClearer() { ClearERRStack(); }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ScopedERRStackClearer);
 };
 
 }  // namespace base
 
-#endif  // BASE_NSS_UTIL_H_
+#endif  // BASE_OPENSSL_UTIL_H_