2 This file is part of GNUnet.
3 (C) 2010, 2011, 2012 Christian Grothoff
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13 General Public License for more details.
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23 * @brief standard IP calculations for TUN interaction
24 * @author Philipp Toelke
25 * @author Christian Grothoff
28 #include "gnunet_tun_lib.h"
31 * IP TTL we use for packets that we assemble (8 bit unsigned integer)
37 * Initialize an IPv4 header.
39 * @param ip header to initialize
40 * @param protocol protocol to use (i.e. IPPROTO_UDP)
41 * @param payload_length number of bytes of payload that follow (excluding IPv4 header)
42 * @param src source IP address to use
43 * @param dst destination IP address to use
46 GNUNET_TUN_initialize_ipv4_header (struct GNUNET_TUN_IPv4Header *ip,
48 uint16_t payload_length,
49 const struct in_addr *src,
50 const struct in_addr *dst)
52 GNUNET_assert (payload_length <= UINT16_MAX - sizeof (struct GNUNET_TUN_IPv4Header));
53 ip->header_length = sizeof (struct GNUNET_TUN_IPv4Header) / 4;
56 ip->total_length = htons (sizeof (struct GNUNET_TUN_IPv4Header) + payload_length);
57 ip->identification = (uint16_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
60 ip->fragmentation_offset = 0;
62 ip->protocol = protocol;
64 ip->source_address = *src;
65 ip->destination_address = *dst;
66 ip->checksum = GNUNET_CRYPTO_crc16_n (ip, sizeof (struct GNUNET_TUN_IPv4Header));
71 * Initialize an IPv6 header.
73 * @param ip header to initialize
74 * @param protocol protocol to use (i.e. IPPROTO_UDP), technically "next_header" for IPv6
75 * @param payload_length number of bytes of payload that follow (excluding IPv4 header)
76 * @param src source IP address to use
77 * @param dst destination IP address to use
80 GNUNET_TUN_initialize_ipv6_header (struct GNUNET_TUN_IPv6Header *ip,
82 uint16_t payload_length,
83 const struct in6_addr *src,
84 const struct in6_addr *dst)
86 GNUNET_assert (payload_length <= UINT16_MAX - sizeof (struct GNUNET_TUN_IPv6Header));
87 ip->traffic_class_h = 0;
89 ip->traffic_class_l = 0;
91 ip->next_header = protocol;
92 ip->payload_length = htons ((uint16_t) (payload_length + sizeof (struct GNUNET_TUN_IPv6Header)));
93 ip->hop_limit = FRESH_TTL;
94 ip->destination_address = *dst;
95 ip->source_address = *src;
100 * Calculate IPv4 TCP checksum.
102 * @param ip ipv4 header fully initialized
103 * @param tcp TCP header (initialized except for CRC)
104 * @param payload the TCP payload
105 * @param payload_length number of bytes of TCP payload
108 GNUNET_TUN_calculate_tcp4_checksum (const struct GNUNET_TUN_IPv4Header *ip,
109 struct GNUNET_TUN_TcpHeader *tcp,
111 uint16_t payload_length)
116 GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_IPv4Header) + sizeof (struct GNUNET_TUN_TcpHeader) ==
117 ntohs (ip->total_length));
118 GNUNET_assert (IPPROTO_TCP == ip->protocol);
121 sum = GNUNET_CRYPTO_crc16_step (0,
123 sizeof (struct in_addr) * 2);
124 tmp = htonl ((IPPROTO_TCP << 16) | (payload_length + sizeof (struct GNUNET_TUN_TcpHeader)));
125 sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
126 sum = GNUNET_CRYPTO_crc16_step (sum, tcp, sizeof (struct GNUNET_TUN_TcpHeader));
127 sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
128 tcp->crc = GNUNET_CRYPTO_crc16_finish (sum);
133 * Calculate IPv6 TCP checksum.
135 * @param ip ipv6 header fully initialized
136 * @param tcp header (initialized except for CRC)
137 * @param payload the TCP payload
138 * @param payload_length number of bytes of TCP payload
141 GNUNET_TUN_calculate_tcp6_checksum (const struct GNUNET_TUN_IPv6Header *ip,
142 struct GNUNET_TUN_TcpHeader *tcp,
144 uint16_t payload_length)
149 GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_IPv6Header) + sizeof (struct GNUNET_TUN_TcpHeader) ==
150 ntohs (ip->payload_length));
151 GNUNET_assert (IPPROTO_TCP == ip->next_header);
153 sum = GNUNET_CRYPTO_crc16_step (0, &ip->source_address, 2 * sizeof (struct in6_addr));
154 tmp = htonl (sizeof (struct GNUNET_TUN_TcpHeader) + payload_length);
155 sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
156 tmp = htonl (IPPROTO_TCP);
157 sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
158 sum = GNUNET_CRYPTO_crc16_step (sum, tcp,
159 sizeof (struct GNUNET_TUN_TcpHeader));
160 sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
161 tcp->crc = GNUNET_CRYPTO_crc16_finish (sum);
166 * Calculate IPv4 UDP checksum.
168 * @param ip ipv4 header fully initialized
169 * @param udp UDP header (initialized except for CRC)
170 * @param payload the UDP payload
171 * @param payload_length number of bytes of UDP payload
174 GNUNET_TUN_calculate_udp4_checksum (const struct GNUNET_TUN_IPv4Header *ip,
175 struct GNUNET_TUN_UdpHeader *udp,
177 uint16_t payload_length)
182 GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_IPv4Header) + sizeof (struct GNUNET_TUN_UdpHeader) ==
183 ntohs (ip->total_length));
184 GNUNET_assert (IPPROTO_UDP == ip->protocol);
186 udp->crc = 0; /* technically optional, but we calculate it anyway, just to be sure */
187 sum = GNUNET_CRYPTO_crc16_step (0,
189 sizeof (struct in_addr) * 2);
190 tmp = htons (IPPROTO_UDP);
191 sum = GNUNET_CRYPTO_crc16_step (sum,
194 tmp = htons (sizeof (struct GNUNET_TUN_UdpHeader) + payload_length);
195 sum = GNUNET_CRYPTO_crc16_step (sum,
198 sum = GNUNET_CRYPTO_crc16_step (sum,
200 sizeof (struct GNUNET_TUN_UdpHeader));
201 sum = GNUNET_CRYPTO_crc16_step (sum,
204 udp->crc = GNUNET_CRYPTO_crc16_finish (sum);
209 * Calculate IPv6 UDP checksum.
211 * @param ip ipv6 header fully initialized
212 * @param udp UDP header (initialized except for CRC)
213 * @param payload the UDP payload
214 * @param payload_length number of bytes of UDP payload
217 GNUNET_TUN_calculate_udp6_checksum (const struct GNUNET_TUN_IPv6Header *ip,
218 struct GNUNET_TUN_UdpHeader *udp,
220 uint16_t payload_length)
225 GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_IPv6Header) + sizeof (struct GNUNET_TUN_UdpHeader) ==
226 ntohs (ip->payload_length));
227 GNUNET_assert (payload_length + sizeof (struct GNUNET_TUN_UdpHeader) ==
229 GNUNET_assert (IPPROTO_UDP == ip->next_header);
232 sum = GNUNET_CRYPTO_crc16_step (0,
234 sizeof (struct in6_addr) * 2);
235 tmp = htons (sizeof (struct GNUNET_TUN_UdpHeader) + payload_length); /* aka udp->len */
236 sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
237 tmp = htons (ip->next_header);
238 sum = GNUNET_CRYPTO_crc16_step (sum, &tmp, sizeof (uint32_t));
239 sum = GNUNET_CRYPTO_crc16_step (sum, udp, sizeof (struct GNUNET_TUN_UdpHeader));
240 sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
241 udp->crc = GNUNET_CRYPTO_crc16_finish (sum);
246 * Calculate ICMP checksum.
248 * @param icmp IMCP header (initialized except for CRC)
249 * @param payload the ICMP payload
250 * @param payload_length number of bytes of ICMP payload
253 GNUNET_TUN_calculate_icmp_checksum (struct GNUNET_TUN_IcmpHeader *icmp,
255 uint16_t payload_length)
260 sum = GNUNET_CRYPTO_crc16_step (0,
262 sizeof (struct GNUNET_TUN_IcmpHeader));
263 sum = GNUNET_CRYPTO_crc16_step (sum, payload, payload_length);
264 icmp->crc = GNUNET_CRYPTO_crc16_finish (sum);