/*
    global.h -- global variables and constants
    Copyright (C) 2003-2013 Marc Lehmann <gvpe@schmorp.de>
 
    This file is part of GVPE.

    GVPE is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the
    Free Software Foundation; either version 3 of the License, or (at your
    option) any later version.
   
    This program is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
    Public License for more details.
   
    You should have received a copy of the GNU General Public License along
    with this program; if not, see <http://www.gnu.org/licenses/>.
   
    Additional permission under GNU GPL version 3 section 7
   
    If you modify this Program, or any covered work, by linking or
    combining it with the OpenSSL project's OpenSSL library (or a modified
    version of that library), containing parts covered by the terms of the
    OpenSSL or SSLeay licenses, the licensors of this Program grant you
    additional permission to convey the resulting work.  Corresponding
    Source for a non-source form of such a combination shall include the
    source code for the parts of OpenSSL used as well as that of the
    covered work.
*/

#ifndef GLOBAL_H__
#define GLOBAL_H__

#include "config.h"

#include <time.h>

/* Protocol version. Different major versions are incompatible,
 * different minor versions probably are compatible ;)
 */

#define PROTOCOL_MAJOR 0
#define PROTOCOL_MINOR 1

#define SEED_SIZE	64 // how many octets to seed rng with

#define RSA_KEYBITS	1280		// must be >= 1280 and divisible by 8
#define RSA_KEYLEN	((RSA_KEYBITS) >> 3)
#define RSA_OVERHEAD	(41 + 1)	// well, no define for OAEP in openssl

#define RSA_HASH	EVP_ripemd160 ()// speed don't matter, boy, safety does.. I need sha256 :(
#define RSA_HASHLEN	(160 >> 3)
#define RSA_RESLEN	RSA_HASHLEN

#define RSA_IDLEN	16		// how many bytes are used to identify the challenge
#define RSA_TTL		120		// challenge bytes timeout after n seconds

#define CIPHER		ENABLE_CIPHER ()
#define CIPHER_KEYLEN	(EVP_CIPHER_key_length (CIPHER))
#define DIGEST		ENABLE_DIGEST ()
#define HMAC_KEYLEN	(256 >> 3)	// number of bits used for the HMAC key

#define WINDOWSIZE	512		// sliding window size
#define MAX_SEQNO	(0xfffffff0U - WINDOWSIZE * 8)

#define CHG_SEQNO	 0					// where the seqno starts within the rsa challenge
#define CHG_CIPHER_KEY	(CHG_SEQNO + 4)				// where the key starts within the rsa challenge
//#define CHG_HMAC_KEY	(CHG_CIPHER_KEY + CIPHER_KEYLEN)	// where the key starts within the rsa challenge
#define CHG_HMAC_KEY	86					// where the key starts within the rsa challenge
// 872 rsa bits used

//                    hdr seq len              hmac        MAC MAC
#define VPE_OVERHEAD  (4 + 4 + 4 + RAND_SIZE + HMACLENGTH - 6 - 6)
#define IP_OVERHEAD   20			// size of a (normal) ip header
#define GRE_OVERHEAD  (IP_OVERHEAD +  4)
#define ICMP_OVERHEAD (IP_OVERHEAD +  4)
#define UDP_OVERHEAD  (IP_OVERHEAD + 20)	// size of a (normal) ip + udp header (wrong, but don't care)
#define TCP_OVERHEAD  (IP_OVERHEAD + 22)	// size of a (normal) ip + tcp header + packetlength
#define MAX_OVERHEAD  UDP_OVERHEAD		// the max. overhead of any protocol (ok, tcp doesn't count)
#define ETH_OVERHEAD  14			// the size of an ethernet header
#define MAXSIZE       (MAX_MTU + VPE_OVERHEAD)	// slightly too large, but who cares

#define PKTCACHESIZE	16	// the size of the memory pool for packets

extern char *confbase;		// directory in which all config files are
extern char *thisnode;		// config for current node (TODO: remove)

template<typename T, typename U> static inline T    min    (T  a, U b) { return a < (T)b ? a : (T)b; }
template<typename T, typename U> static inline void min_it (T &a, U b) {    a = a < (T)b ? a : (T)b; }
template<typename T, typename U> static inline T    max    (T  a, U b) { return a > (T)b ? a : (T)b; }
template<typename T, typename U> static inline void max_it (T &a, U b) {    a = a > (T)b ? a : (T)b; }

template<typename T, typename U, typename V> static inline T clamp (T  v, U a, V b) { return v < (T)a ? a : v >(T)b ? b : v; }

template<typename T, typename U> static inline void swap (T& a, U& b) { T t=a; a=(T)b; b=(U)t; }

#endif