lib/packets.h

   1 /*
   2  * Copyright (c) 2008, 2009 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #ifndef PACKETS_H
  17 #define PACKETS_H 1
  18
  19 #include <inttypes.h>
  20 #include <stdint.h>
  21 #include <string.h>
  22 #include "compiler.h"
  23 #include "random.h"
  24 #include "util.h"
  25
  26 #define ETH_ADDR_LEN           6
  27
  28 static const uint8_t eth_addr_broadcast[ETH_ADDR_LEN] UNUSED
  29     = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  30
  31 static inline bool eth_addr_is_broadcast(const uint8_t ea[6])
  32 {
  33     return (ea[0] & ea[1] & ea[2] & ea[3] & ea[4] & ea[5]) == 0xff;
  34 }
  35
  36 /* Returns true if 'ea' is an Ethernet address used for virtual interfaces
  37  * under XenServer.  Generally the actual Ethernet address is FE:FF:FF:FF:FF:FF
  38  * but it can be FE:FE:FE:FE:FE:FE in some cases. */
  39 static inline bool eth_addr_is_vif(const uint8_t ea[6])
  40 {
  41     return ea[0] == 0xfe && (ea[1] & ea[2] & ea[3] & ea[4] & ea[5]) >= 0xfe;
  42 }
  43
  44 static inline bool eth_addr_is_multicast(const uint8_t ea[6])
  45 {
  46     return ea[0] & 1;
  47 }
  48 static inline bool eth_addr_is_local(const uint8_t ea[6])
  49 {
  50     return ea[0] & 2;
  51 }
  52 static inline bool eth_addr_is_zero(const uint8_t ea[6])
  53 {
  54     return !(ea[0] | ea[1] | ea[2] | ea[3] | ea[4] | ea[5]);
  55 }
  56 static inline bool eth_addr_equals(const uint8_t a[ETH_ADDR_LEN],
  57                                    const uint8_t b[ETH_ADDR_LEN])
  58 {
  59     return !memcmp(a, b, ETH_ADDR_LEN);
  60 }
  61 static inline uint64_t eth_addr_to_uint64(const uint8_t ea[ETH_ADDR_LEN])
  62 {
  63     return (((uint64_t) ea[0] << 40)
  64             | ((uint64_t) ea[1] << 32)
  65             | ((uint64_t) ea[2] << 24)
  66             | ((uint64_t) ea[3] << 16)
  67             | ((uint64_t) ea[4] << 8)
  68             | ea[5]);
  69 }
  70 static inline void eth_addr_from_uint64(uint64_t x, uint8_t ea[ETH_ADDR_LEN])
  71 {
  72     ea[0] = x >> 40;
  73     ea[1] = x >> 32;
  74     ea[2] = x >> 24;
  75     ea[3] = x >> 16;
  76     ea[4] = x >> 8;
  77     ea[5] = x;
  78 }
  79 static inline void eth_addr_mark_random(uint8_t ea[ETH_ADDR_LEN])
  80 {
  81     ea[0] &= ~1;                /* Unicast. */
  82     ea[0] |= 2;                 /* Private. */
  83 }
  84 static inline void eth_addr_random(uint8_t ea[ETH_ADDR_LEN])
  85 {
  86     random_bytes(ea, ETH_ADDR_LEN);
  87     eth_addr_mark_random(ea);
  88 }
  89 /* Returns true if 'ea' is a reserved multicast address, that a bridge must
  90  * never forward, false otherwise. */
  91 static inline bool eth_addr_is_reserved(const uint8_t ea[ETH_ADDR_LEN])
  92 {
  93     return (ea[0] == 0x01
  94             && ea[1] == 0x80
  95             && ea[2] == 0xc2
  96             && ea[3] == 0x00
  97             && ea[4] == 0x00
  98             && (ea[5] & 0xf0) == 0x00);
  99 }
 100
 101 #define ETH_ADDR_FMT                                                    \
 102     "%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8":%02"PRIx8
 103 #define ETH_ADDR_ARGS(ea)                                   \
 104     (ea)[0], (ea)[1], (ea)[2], (ea)[3], (ea)[4], (ea)[5]
 105
 106 #define ETH_TYPE_IP            0x0800
 107 #define ETH_TYPE_ARP           0x0806
 108 #define ETH_TYPE_VLAN          0x8100
 109
 110 #define ETH_HEADER_LEN 14
 111 #define ETH_PAYLOAD_MIN 46
 112 #define ETH_PAYLOAD_MAX 1500
 113 #define ETH_TOTAL_MIN (ETH_HEADER_LEN + ETH_PAYLOAD_MIN)
 114 #define ETH_TOTAL_MAX (ETH_HEADER_LEN + ETH_PAYLOAD_MAX)
 115 #define ETH_VLAN_TOTAL_MAX (ETH_HEADER_LEN + VLAN_HEADER_LEN + ETH_PAYLOAD_MAX)
 116 struct eth_header {
 117     uint8_t eth_dst[ETH_ADDR_LEN];
 118     uint8_t eth_src[ETH_ADDR_LEN];
 119     uint16_t eth_type;
 120 } __attribute__((packed));
 121 BUILD_ASSERT_DECL(ETH_HEADER_LEN == sizeof(struct eth_header));
 122
 123 #define LLC_DSAP_SNAP 0xaa
 124 #define LLC_SSAP_SNAP 0xaa
 125 #define LLC_CNTL_SNAP 3
 126
 127 #define LLC_HEADER_LEN 3
 128 struct llc_header {
 129     uint8_t llc_dsap;
 130     uint8_t llc_ssap;
 131     uint8_t llc_cntl;
 132 } __attribute__((packed));
 133 BUILD_ASSERT_DECL(LLC_HEADER_LEN == sizeof(struct llc_header));
 134
 135 #define SNAP_ORG_ETHERNET "\0\0" /* The compiler adds a null byte, so
 136                                     sizeof(SNAP_ORG_ETHERNET) == 3. */
 137 #define SNAP_HEADER_LEN 5
 138 struct snap_header {
 139     uint8_t snap_org[3];
 140     uint16_t snap_type;
 141 } __attribute__((packed));
 142 BUILD_ASSERT_DECL(SNAP_HEADER_LEN == sizeof(struct snap_header));
 143
 144 #define LLC_SNAP_HEADER_LEN (LLC_HEADER_LEN + SNAP_HEADER_LEN)
 145 struct llc_snap_header {
 146     struct llc_header llc;
 147     struct snap_header snap;
 148 } __attribute__((packed));
 149 BUILD_ASSERT_DECL(LLC_SNAP_HEADER_LEN == sizeof(struct llc_snap_header));
 150
 151 #define VLAN_VID_MASK 0x0fff
 152 #define VLAN_PCP_MASK 0xe000
 153
 154 #define VLAN_HEADER_LEN 4
 155 struct vlan_header {
 156     uint16_t vlan_tci;          /* Lowest 12 bits are VLAN ID. */
 157     uint16_t vlan_next_type;
 158 };
 159 BUILD_ASSERT_DECL(VLAN_HEADER_LEN == sizeof(struct vlan_header));
 160
 161 #define VLAN_ETH_HEADER_LEN (ETH_HEADER_LEN + VLAN_HEADER_LEN)
 162 struct vlan_eth_header {
 163     uint8_t veth_dst[ETH_ADDR_LEN];
 164     uint8_t veth_src[ETH_ADDR_LEN];
 165     uint16_t veth_type;         /* Always htons(ETH_TYPE_VLAN). */
 166     uint16_t veth_tci;          /* Lowest 12 bits are VLAN ID. */
 167     uint16_t veth_next_type;
 168 } __attribute__((packed));
 169 BUILD_ASSERT_DECL(VLAN_ETH_HEADER_LEN == sizeof(struct vlan_eth_header));
 170
 171 /* The "(void) (ip)[0]" below has no effect on the value, since it's the first
 172  * argument of a comma expression, but it makes sure that 'ip' is a pointer.
 173  * This is useful since a common mistake is to pass an integer instead of a
 174  * pointer to IP_ARGS. */
 175 #define IP_FMT "%"PRIu8".%"PRIu8".%"PRIu8".%"PRIu8
 176 #define IP_ARGS(ip)                             \
 177         ((void) (ip)[0], ((uint8_t *) ip)[0]),  \
 178         ((uint8_t *) ip)[1],                    \
 179         ((uint8_t *) ip)[2],                    \
 180         ((uint8_t *) ip)[3]
 181
 182 #define IP_VER(ip_ihl_ver) ((ip_ihl_ver) >> 4)
 183 #define IP_IHL(ip_ihl_ver) ((ip_ihl_ver) & 15)
 184 #define IP_IHL_VER(ihl, ver) (((ver) << 4) | (ihl))
 185
 186 #define IP_TYPE_ICMP 1
 187 #define IP_TYPE_TCP 6
 188 #define IP_TYPE_UDP 17
 189
 190 #define IP_VERSION 4
 191
 192 #define IP_DONT_FRAGMENT  0x4000 /* Don't fragment. */
 193 #define IP_MORE_FRAGMENTS 0x2000 /* More fragments. */
 194 #define IP_FRAG_OFF_MASK  0x1fff /* Fragment offset. */
 195 #define IP_IS_FRAGMENT(ip_frag_off) \
 196         ((ip_frag_off) & htons(IP_MORE_FRAGMENTS | IP_FRAG_OFF_MASK))
 197
 198 #define IP_HEADER_LEN 20
 199 struct ip_header {
 200     uint8_t ip_ihl_ver;
 201     uint8_t ip_tos;
 202     uint16_t ip_tot_len;
 203     uint16_t ip_id;
 204     uint16_t ip_frag_off;
 205     uint8_t ip_ttl;
 206     uint8_t ip_proto;
 207     uint16_t ip_csum;
 208     uint32_t ip_src;
 209     uint32_t ip_dst;
 210 };
 211 BUILD_ASSERT_DECL(IP_HEADER_LEN == sizeof(struct ip_header));
 212
 213 #define ICMP_HEADER_LEN 4
 214 struct icmp_header {
 215     uint8_t icmp_type;
 216     uint8_t icmp_code;
 217     uint16_t icmp_csum;
 218 };
 219 BUILD_ASSERT_DECL(ICMP_HEADER_LEN == sizeof(struct icmp_header));
 220
 221 #define UDP_HEADER_LEN 8
 222 struct udp_header {
 223     uint16_t udp_src;
 224     uint16_t udp_dst;
 225     uint16_t udp_len;
 226     uint16_t udp_csum;
 227 };
 228 BUILD_ASSERT_DECL(UDP_HEADER_LEN == sizeof(struct udp_header));
 229
 230 #define TCP_FIN 0x01
 231 #define TCP_SYN 0x02
 232 #define TCP_RST 0x04
 233 #define TCP_PSH 0x08
 234 #define TCP_ACK 0x10
 235 #define TCP_URG 0x20
 236
 237 #define TCP_FLAGS(tcp_ctl) (htons(tcp_ctl) & 0x003f)
 238 #define TCP_OFFSET(tcp_ctl) (htons(tcp_ctl) >> 12)
 239
 240 #define TCP_HEADER_LEN 20
 241 struct tcp_header {
 242     uint16_t tcp_src;
 243     uint16_t tcp_dst;
 244     uint32_t tcp_seq;
 245     uint32_t tcp_ack;
 246     uint16_t tcp_ctl;
 247     uint16_t tcp_winsz;
 248     uint16_t tcp_csum;
 249     uint16_t tcp_urg;
 250 };
 251 BUILD_ASSERT_DECL(TCP_HEADER_LEN == sizeof(struct tcp_header));
 252
 253 #define ARP_HRD_ETHERNET 1
 254 #define ARP_PRO_IP 0x0800
 255 #define ARP_OP_REQUEST 1
 256 #define ARP_OP_REPLY 2
 257
 258 #define ARP_ETH_HEADER_LEN 28
 259 struct arp_eth_header {
 260     /* Generic members. */
 261     uint16_t ar_hrd;           /* Hardware type. */
 262     uint16_t ar_pro;           /* Protocol type. */
 263     uint8_t ar_hln;            /* Hardware address length. */
 264     uint8_t ar_pln;            /* Protocol address length. */
 265     uint16_t ar_op;            /* Opcode. */
 266
 267     /* Ethernet+IPv4 specific members. */
 268     uint8_t ar_sha[ETH_ADDR_LEN]; /* Sender hardware address. */
 269     uint32_t ar_spa;           /* Sender protocol address. */
 270     uint8_t ar_tha[ETH_ADDR_LEN]; /* Target hardware address. */
 271     uint32_t ar_tpa;           /* Target protocol address. */
 272 } __attribute__((packed));
 273 BUILD_ASSERT_DECL(ARP_ETH_HEADER_LEN == sizeof(struct arp_eth_header));
 274
 275 #endif /* packets.h */