Add a runtime map of string->func() which when called return

Transforms and BlockCiphers. Registration for all types is done at
startup but is very cheap as just a std::function and a std::map entry
are created, no actual objects are created until needed. This is a
huge improvement over Algorithm_Factory which used T::clone() as the
function and thus kept a prototype object of each type in memory.

Replace existing lookup mechanisms for ciphers, AEADs, and compression
to use the transform lookup. The existing Engine framework remains in
place for BlockCipher, but the engines now just call to the registry
instead of having hardcoded lookups.

s/Transformation/Transform/ with typedefs for compatability.

Remove lib/selftest code (for runtime selftesting): not the right approach.

1 files changed, 59 insertions, 0 deletions

diff --git a/src/lib/modes/cipher_mode.cpp b/src/lib/modes/cipher_mode.cpp
new file mode 100644
index 000000000..ded7b4c81
--- /dev/null
+++ b/src/lib/modes/cipher_mode.cpp
@@ -0,0 +1,59 @@
+/*
+* Cipher Modes
+* (C) 2015 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/cipher_mode.h>
+#include <sstream>
+
+namespace Botan {
+
+Cipher_Mode* get_cipher_mode(const std::string& algo_spec, Cipher_Dir direction)
+   {
+   const char* dir_string = (direction == ENCRYPTION) ? "_Encryption" : "_Decryption";
+
+   const std::string provider = "";
+
+   std::unique_ptr<Transform> t;
+
+   t.reset(get_transform(algo_spec, provider, dir_string));
+
+   if(Cipher_Mode* cipher = dynamic_cast<Cipher_Mode*>(t.get()))
+      {
+      t.release();
+      return cipher;
+      }
+
+   const std::vector<std::string> algo_parts = split_on(algo_spec, '/');
+   if(algo_parts.size() < 2)
+      return nullptr;
+
+   const std::string cipher_name = algo_parts[0];
+   const std::vector<std::string> mode_info = parse_algorithm_name(algo_parts[1]);
+
+   if(mode_info.empty())
+      return nullptr;
+
+   std::ostringstream t_name;
+
+   t_name << mode_info[0] << dir_string << '(' << cipher_name;
+   for(size_t i = 1; i < mode_info.size(); ++i)
+      t_name << ',' << mode_info[i];
+   for(size_t i = 2; i < algo_parts.size(); ++i)
+      t_name << ',' << algo_parts[i];
+   t_name << ')';
+
+   t.reset(get_transform(t_name.str(), provider));
+
+   if(Cipher_Mode* cipher = dynamic_cast<Cipher_Mode*>(t.get()))
+      {
+      t.release();
+      return cipher;
+      }
+
+   return nullptr;
+   }
+
+}