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/*
This file is part of GNUnet.
Copyright (C) 2010, 2011, 2012 Christian Grothoff
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.
GNUnet 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
Affero General Public License for more details.
*/
/**
* @file tun/tun.c
* @brief standard IP calculations for TUN interaction
* @author Philipp Toelke
* @author Christian Grothoff
*/
#include "platform.h"
#include "gnunet_tun_lib.h"
/**
* IP TTL we use for packets that we assemble (8 bit unsigned integer)
*/
#define FRESH_TTL 64
/**
* Initialize an IPv4 header.
*
* @param ip header to initialize
* @param protocol protocol to use (i.e. IPPROTO_UDP)
* @param payload_length number of bytes of payload that follow (excluding IPv4 header)
* @param src source IP address to use
* @param dst destination IP address to use
*/
void
GNUNET_TUN_initialize_ipv4_header (struct GNUNET_TUN_IPv4Header *ip,
uint8_t protocol,
uint16_t payload_length,
const struct in_addr *src,
const struct in_addr *dst)
{
GNUNET_assert (20 == sizeof (struct GNUNET_TUN_IPv4Header));
GNUNET_assert (payload_length <= UINT16_MAX - sizeof (struct GNUNET_TUN_IPv4Header));
memset (ip, 0, sizeof (struct GNUNET_TUN_IPv4Header));
ip->header_length = sizeof (struct GNUNET_TUN_IPv4Header) / 4;
ip->version = 4;
ip->total_length = htons (sizeof (struct GNUNET_TUN_IPv4Header) + payload_length);
ip->identification = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
65536);
ip->ttl = FRESH_TTL;
ip->protocol = protocol;
ip->source_address = *src;
ip->destination_address = *dst;
ip->checksum = GNUNET_CRYPTO_crc16_n (ip, sizeof (struct GNUNET_TUN_IPv4Header));
}
/**
* Initialize an IPv6 header.
*
* @param ip header to initialize
* @param protocol protocol to use (i.e. IPPROTO_UDP), technically "next_header" for IPv6
* @param payload_length number of bytes of payload that follow (excluding IPv6 header)
* @param src source IP address to use
* @param dst destination IP address to use
*/
void
GNUNET_TUN_initialize_ipv6_header (struct GNUNET_TUN_IPv6Header *ip,
uint8_t protocol,
uint16_t payload_length,
const struct in6_addr *src,
const struct in6_addr *dst)
{
GNUNET_assert (40 == sizeof (struct GNUNET_TUN_IPv6Header));
GNUNET_assert (payload_length <= UINT16_MAX - sizeof (struct GNUNET_TUN_IPv6Header));
memset (ip, 0, sizeof (struct GNUNET_TUN_IPv6Header));
ip->version = 6;
ip->next_header = protocol;
ip->payload_length = htons ((uint16_t) payload_length);
ip->hop_limit = FRESH_TTL;
ip->destination_address = *dst;
ip->source_address = *src;
}
/**
* Calculate IPv4 TCP checksum.
*
* @param ip ipv4 header fully initialized
* @param tcp TCP header (initialized except for CRC)
* @param payload the TCP payload
* @param payload_length number of bytes of TCP payload
*/
void
GNUNET_TUN_calculate_tcp4_checksum (const struct GNUNET_TUN_IPv4Header *ip,
struct GNUNET_TUN_TcpHeader *tcp,
const void *payload,
uint16_t payload_length)
{
uint32_t sum;
uint16_t tmp;
GNUNET_assert (20 == sizeof (struct GNUNET_TUN_TcpHeader));
GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_IPv4Header) + sizeof (struct GNUNET_TUN_TcpHeader) ==
ntohs (ip->total_length));
GNUNET_assert (IPPROTO_TCP == ip->protocol);
tcp->crc = 0;
sum = GNUNET_CRYPTO_crc16_step (0,
&ip->source_address,
sizeof (struct in_addr) * 2);
tmp = htons (IPPROTO_TCP);
sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint16_t));
tmp = htons (payload_length + sizeof (struct GNUNET_TUN_TcpHeader));
sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint16_t));
sum = GNUNET_CRYPTO_crc16_step (sum, tcp, sizeof (struct GNUNET_TUN_TcpHeader));
sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
tcp->crc = GNUNET_CRYPTO_crc16_finish (sum);
}
/**
* Calculate IPv6 TCP checksum.
*
* @param ip ipv6 header fully initialized
* @param tcp header (initialized except for CRC)
* @param payload the TCP payload
* @param payload_length number of bytes of TCP payload
*/
void
GNUNET_TUN_calculate_tcp6_checksum (const struct GNUNET_TUN_IPv6Header *ip,
struct GNUNET_TUN_TcpHeader *tcp,
const void *payload,
uint16_t payload_length)
{
uint32_t sum;
uint32_t tmp;
GNUNET_assert (20 == sizeof (struct GNUNET_TUN_TcpHeader));
GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_TcpHeader) ==
ntohs (ip->payload_length));
GNUNET_assert (IPPROTO_TCP == ip->next_header);
tcp->crc = 0;
sum = GNUNET_CRYPTO_crc16_step (0, &ip->source_address, 2 * sizeof (struct in6_addr));
tmp = htonl (sizeof (struct GNUNET_TUN_TcpHeader) + payload_length);
sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
tmp = htonl (IPPROTO_TCP);
sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
sum = GNUNET_CRYPTO_crc16_step (sum, tcp,
sizeof (struct GNUNET_TUN_TcpHeader));
sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
tcp->crc = GNUNET_CRYPTO_crc16_finish (sum);
}
/**
* Calculate IPv4 UDP checksum.
*
* @param ip ipv4 header fully initialized
* @param udp UDP header (initialized except for CRC)
* @param payload the UDP payload
* @param payload_length number of bytes of UDP payload
*/
void
GNUNET_TUN_calculate_udp4_checksum (const struct GNUNET_TUN_IPv4Header *ip,
struct GNUNET_TUN_UdpHeader *udp,
const void *payload,
uint16_t payload_length)
{
uint32_t sum;
uint16_t tmp;
GNUNET_assert (8 == sizeof (struct GNUNET_TUN_UdpHeader));
GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_IPv4Header) + sizeof (struct GNUNET_TUN_UdpHeader) ==
ntohs (ip->total_length));
GNUNET_assert (IPPROTO_UDP == ip->protocol);
udp->crc = 0; /* technically optional, but we calculate it anyway, just to be sure */
sum = GNUNET_CRYPTO_crc16_step (0,
&ip->source_address,
sizeof (struct in_addr) * 2);
tmp = htons (IPPROTO_UDP);
sum = GNUNET_CRYPTO_crc16_step (sum,
&tmp,
sizeof (uint16_t));
tmp = htons (sizeof (struct GNUNET_TUN_UdpHeader) + payload_length);
sum = GNUNET_CRYPTO_crc16_step (sum,
&tmp,
sizeof (uint16_t));
sum = GNUNET_CRYPTO_crc16_step (sum,
udp,
sizeof (struct GNUNET_TUN_UdpHeader));
sum = GNUNET_CRYPTO_crc16_step (sum,
payload,
payload_length);
udp->crc = GNUNET_CRYPTO_crc16_finish (sum);
}
/**
* Calculate IPv6 UDP checksum.
*
* @param ip ipv6 header fully initialized
* @param udp UDP header (initialized except for CRC)
* @param payload the UDP payload
* @param payload_length number of bytes of UDP payload
*/
void
GNUNET_TUN_calculate_udp6_checksum (const struct GNUNET_TUN_IPv6Header *ip,
struct GNUNET_TUN_UdpHeader *udp,
const void *payload,
uint16_t payload_length)
{
uint32_t sum;
uint32_t tmp;
GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_UdpHeader) ==
ntohs (ip->payload_length));
GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_UdpHeader) ==
ntohs (udp->len));
GNUNET_assert (IPPROTO_UDP == ip->next_header);
udp->crc = 0;
sum = GNUNET_CRYPTO_crc16_step (0,
&ip->source_address,
sizeof (struct in6_addr) * 2);
tmp = htons (sizeof (struct GNUNET_TUN_UdpHeader) + payload_length); /* aka udp->len */
sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
tmp = htons (ip->next_header);
sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
sum = GNUNET_CRYPTO_crc16_step (sum, udp, sizeof (struct GNUNET_TUN_UdpHeader));
sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
udp->crc = GNUNET_CRYPTO_crc16_finish (sum);
}
/**
* Calculate ICMP checksum.
*
* @param icmp IMCP header (initialized except for CRC)
* @param payload the ICMP payload
* @param payload_length number of bytes of ICMP payload
*/
void
GNUNET_TUN_calculate_icmp_checksum (struct GNUNET_TUN_IcmpHeader *icmp,
const void *payload,
uint16_t payload_length)
{
uint32_t sum;
GNUNET_assert (8 == sizeof (struct GNUNET_TUN_IcmpHeader));
icmp->crc = 0;
sum = GNUNET_CRYPTO_crc16_step (0,
icmp,
sizeof (struct GNUNET_TUN_IcmpHeader));
sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
icmp->crc = GNUNET_CRYPTO_crc16_finish (sum);
}
/**
* Check if two sockaddrs are equal.
*
* @param sa one address
* @param sb another address
* @param include_port also check ports
* @return #GNUNET_YES if they are equal
*/
int
GNUNET_TUN_sockaddr_cmp (const struct sockaddr *sa,
const struct sockaddr *sb,
int include_port)
{
if (sa->sa_family != sb->sa_family)
return GNUNET_NO;
switch (sa->sa_family)
{
case AF_INET:
{
const struct sockaddr_in *sa4 = (const struct sockaddr_in *) sa;
const struct sockaddr_in *sb4 = (const struct sockaddr_in *) sb;
return (sa4->sin_addr.s_addr == sb4->sin_addr.s_addr);
}
case AF_INET6:
{
const struct sockaddr_in6 *sa6 = (const struct sockaddr_in6 *) sa;
const struct sockaddr_in6 *sb6 = (const struct sockaddr_in6 *) sb;
return (0 == memcmp(&sa6->sin6_addr,
&sb6->sin6_addr,
sizeof (struct in6_addr)));
}
default:
GNUNET_break (0);
return GNUNET_SYSERR;
}
}
/* end of tun.c */
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