mirror of
https://github.com/OpenVPN/openvpn3.git
synced 2024-09-20 12:12:15 +02:00
102 lines
2.5 KiB
C++
102 lines
2.5 KiB
C++
// OpenVPN -- An application to securely tunnel IP networks
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// over a single port, with support for SSL/TLS-based
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// session authentication and key exchange,
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// packet encryption, packet authentication, and
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// packet compression.
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//
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// Copyright (C) 2012-2017 OpenVPN Technologies, Inc.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License Version 3
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// as published by the Free Software Foundation.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program in the COPYING file.
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// If not, see <http://www.gnu.org/licenses/>.
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// Define the IP protocol header
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#ifndef OPENVPN_IP_IP_H
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#define OPENVPN_IP_IP_H
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#include <cstdint> // for std::uint32_t, uint16_t, uint8_t
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#pragma pack(push)
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#pragma pack(1)
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namespace openvpn {
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struct IPHeader
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{
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static unsigned int version(const std::uint8_t version_len)
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{
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return (version_len >> 4) & 0x0F;
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}
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static unsigned int length(const std::uint8_t version_len)
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{
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return (version_len & 0x0F) << 2;
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}
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static std::uint8_t ver_len(const unsigned int version,
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const unsigned int len)
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{
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return ((len >> 2) & 0x0F) | (version & 0x0F) << 4;
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}
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std::uint8_t version_len;
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std::uint8_t tos;
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std::uint16_t tot_len;
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std::uint16_t id;
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enum {
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OFFMASK=0x1fff,
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};
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std::uint16_t frag_off;
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std::uint8_t ttl;
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enum {
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ICMP = 1, /* ICMP protocol */
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IGMP = 2, /* IGMP protocol */
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TCP = 6, /* TCP protocol */
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UDP = 17, /* UDP protocol */
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};
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std::uint8_t protocol;
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std::uint16_t check;
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std::uint32_t saddr;
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std::uint32_t daddr;
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/* The options start here. */
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};
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inline std::uint16_t ip_checksum(const void *ip, unsigned int size)
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{
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std::uint16_t *buffer = (std::uint16_t *)ip;
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std::uint32_t cksum = 0;
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while (size > 1)
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{
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cksum += *buffer++;
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size -= sizeof(uint16_t);
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}
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if (size)
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cksum += *(uint8_t*)buffer;
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cksum = (cksum >> 16) + (cksum & 0xffff);
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cksum += (cksum >> 16);
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return ~cksum;
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}
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}
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#pragma pack(pop)
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#endif
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