External Public-Key Authentication API (#72) * Implemented dynamic loading of an external plug-in shared library to delegate public key authentication * Moved conditional compilation of the plugin infrastructure into the configure.ac script to be able to add -ldl to dropbear build only when the flag is enabled * Added tags file to the ignore list * Updated API to have the constructor to return function pointers in the pliugin instance. Added support for passing user name to the checkpubkey function. Added options to the session returned by the plugin and have dropbear to parse and process them * Added -rdynamic to the linker flags when EPKA is enabled * Changed the API to pass a previously created session to the checkPubKey function (created during preauth) * Added documentation to the API * Added parameter addrstring to plugin creation function * Modified the API to retrieve the auth options. Instead of having them as field of the EPKASession struct, they are stored internally (plugin-dependent) in the plugin/session and retrieved through a pointer to a function (in the session) * Changed option string to be a simple char * instead of unsigned char *

#ifndef DROPBEAR_DBHELPERS_H_
#define DROPBEAR_DBHELPERS_H_

/* This header defines some things that are also used by libtomcrypt/math. 
   We avoid including normal include.h since that can result in conflicting 
   definitions - only include config.h */
#include "config.h"

#ifdef __GNUC__
#define ATTRIB_PRINTF(fmt,args) __attribute__((format(printf, fmt, args))) 
#define ATTRIB_NORETURN __attribute__((noreturn))
#define ATTRIB_SENTINEL __attribute__((sentinel))
#else
#define ATTRIB_PRINTF(fmt,args)
#define ATTRIB_NORETURN
#define ATTRIB_SENTINEL
#endif

void m_burn(void* data, unsigned int len);

#endif /* DROPBEAR_DBHELPERS_H_ */