Implements Signature Creator & Verifier 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_OPENSSL_UTIL_H_
 #define BASE_OPENSSL_UTIL_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/tracked.h"
 
 namespace base {
 
 // A helper class that takes care of destroying OpenSSL objects when it goes out
 // of scope.
 template <typename T, void (*destructor)(T*)>
 class ScopedOpenSSL {
  public:
-  explicit ScopedOpenSSL(T* ptr_) : ptr_(ptr_) { }
+  ScopedOpenSSL() : ptr_(NULL) { }
+  explicit ScopedOpenSSL(T* ptr) : ptr_(ptr) { }
   ~ScopedOpenSSL() { if (ptr_) (*destructor)(ptr_); }
 
   T* get() const { return ptr_; }
+  void reset(T* ptr) {
+    if (ptr != ptr_) {
+      if (ptr_) (*destructor)(ptr_);
+      ptr_ = ptr;
+    }
+  }
 
  private:
   T* ptr_;
 };
 
 // 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_|
@@ skipping 32 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ScopedOpenSSLSafeSizeBuffer);
 };
 
 // Initialize OpenSSL if it isn't already initialized. This must be called
 // before any other OpenSSL functions.
 // This function is thread-safe, and OpenSSL will only ever be initialized once.
 // OpenSSL will be properly shut down on program exit.
 void EnsureOpenSSLInit();
 
 // 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.
+// are send to VLOG(1), on a release build they are disregarded. An optional
+// |message| can be passed, which will be prepended to the error stack output
+// if present.
+void ClearOpenSSLERRStack(const char* message);

[wtc, 2010/11/17 20:30:48]

Please consult the Style Guide's recommendations on
function overloading and optional arguments.  I remember
they're discouraged in general but allowed in some cases,
but I don't remember the details.

[joth, 2010/11/18 12:52:47]

Done.
It falls under the "overloads must be obvious" subjectiveness test.
I had a better idea though and removed the overload, and updated all callsites
to pass FROM_HERE instead as this seems generally better.

 void ClearOpenSSLERRStack();
 
+// Place an instance of this class on the call stack to automatically clear
+// the OpenSSL error stack on function exit. If |message| is not null it will
+// be included in any error dump.
+class OpenSSLErrStackTracer {
+ public:
+  explicit OpenSSLErrStackTracer(const char* message) : message_(message) {}
+  ~OpenSSLErrStackTracer() { ClearOpenSSLERRStack(message_); }
+
+ private:
+  const char* const message_;
+};
+
 }  // namespace base
 
 #endif  // BASE_OPENSSL_UTIL_H_