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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@openvpn.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* 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 (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef PROTO_H
#define PROTO_H
#include "buffer.h"
/*
* Tunnel types
*/
#define DEV_TYPE_UNDEF 0
#define DEV_TYPE_NULL 1
#define DEV_TYPE_TUN 2 /* point-to-point IP tunnel */
#define DEV_TYPE_TAP 3 /* ethernet (802.3) tunnel */
/*
* IP and Ethernet protocol structs. For portability,
* OpenVPN needs its own definitions of these structs, and
* names have been adjusted to avoid collisions with
* native structs.
*/
#define OPENVPN_ETH_ALEN 6 /* ethernet address length */
struct openvpn_ethhdr
{
uint8_t dest[OPENVPN_ETH_ALEN]; /* destination ethernet addr */
uint8_t source[OPENVPN_ETH_ALEN]; /* source ethernet addr */
# define OPENVPN_ETH_P_IPV4 0x0800 /* IPv4 protocol */
# define OPENVPN_ETH_P_IPV6 0x86DD /* IPv6 protocol */
# define OPENVPN_ETH_P_ARP 0x0806 /* ARP protocol */
uint16_t proto; /* packet type ID field */
};
struct openvpn_iphdr {
# define OPENVPN_IPH_GET_VER(v) (((v) >> 4) & 0x0F)
# define OPENVPN_IPH_GET_LEN(v) (((v) & 0x0F) << 2)
uint8_t version_len;
uint8_t tos;
uint16_t tot_len;
uint16_t id;
# define OPENVPN_IP_OFFMASK 0x1fff
uint16_t frag_off;
uint8_t ttl;
# define OPENVPN_IPPROTO_IGMP 2 /* IGMP protocol */
# define OPENVPN_IPPROTO_TCP 6 /* TCP protocol */
# define OPENVPN_IPPROTO_UDP 17 /* UDP protocol */
uint8_t protocol;
uint16_t check;
uint32_t saddr;
uint32_t daddr;
/*The options start here. */
};
/*
* UDP header
*/
struct openvpn_udphdr {
uint16_t source;
uint16_t dest;
uint16_t len;
uint16_t check;
};
/*
* TCP header, per RFC 793.
*/
struct openvpn_tcphdr {
uint16_t source; /* source port */
uint16_t dest; /* destination port */
uint32_t seq; /* sequence number */
uint32_t ack_seq; /* acknowledgement number */
# define OPENVPN_TCPH_GET_DOFF(d) (((d) & 0xF0) >> 2)
uint8_t doff_res;
# define OPENVPN_TCPH_FIN_MASK (1<<0)
# define OPENVPN_TCPH_SYN_MASK (1<<1)
# define OPENVPN_TCPH_RST_MASK (1<<2)
# define OPENVPN_TCPH_PSH_MASK (1<<3)
# define OPENVPN_TCPH_ACK_MASK (1<<4)
# define OPENVPN_TCPH_URG_MASK (1<<5)
# define OPENVPN_TCPH_ECE_MASK (1<<6)
# define OPENVPN_TCPH_CWR_MASK (1<<7)
uint8_t flags;
uint16_t window;
uint16_t check;
uint16_t urg_ptr;
};
#define OPENVPN_TCPOPT_EOL 0
#define OPENVPN_TCPOPT_NOP 1
#define OPENVPN_TCPOPT_MAXSEG 2
#define OPENVPN_TCPOLEN_MAXSEG 4
/*
* The following macro is used to update an
* internet checksum. "acc" is a 32-bit
* accumulation of all the changes to the
* checksum (adding in old 16-bit words and
* subtracting out new words), and "cksum"
* is the checksum value to be updated.
*/
#define ADJUST_CHECKSUM(acc, cksum) { \
(acc) += (cksum); \
if ((acc) < 0) { \
(acc) = -(acc); \
(acc) = ((acc) >> 16) + ((acc) & 0xffff); \
(acc) += (acc) >> 16; \
(cksum) = (uint16_t) ~(acc); \
} else { \
(acc) = ((acc) >> 16) + ((acc) & 0xffff); \
(acc) += (acc) >> 16; \
(cksum) = (uint16_t) (acc); \
} \
}
/*
* We are in a "liberal" position with respect to MSS,
* i.e. we assume that MSS can be calculated from MTU
* by subtracting out only the IP and TCP header sizes
* without options.
*
* (RFC 879, section 7).
*/
#define MTU_TO_MSS(mtu) (mtu - sizeof(struct openvpn_iphdr) \
- sizeof(struct openvpn_tcphdr))
/*
* If raw tunnel packet is IPv4, return true and increment
* buffer offset to start of IP header.
*/
bool is_ipv4 (int tunnel_type, struct buffer *buf);
#endif
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