trafgen_l4.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Subject to the GPL, version 2.
   4  */
   5
   6 #include <stdbool.h>
   7 #include <netinet/in.h>
   8
   9 #include "die.h"
  10 #include "csum.h"
  11 #include "built_in.h"
  12 #include "trafgen_l3.h"
  13 #include "trafgen_l4.h"
  14 #include "trafgen_conf.h"
  15 #include "trafgen_proto.h"
  16
  17 static struct proto_field udp_fields[] = {
  18         { .id = UDP_SPORT, .len = 2, .offset = 0 },
  19         { .id = UDP_DPORT, .len = 2, .offset = 2 },
  20         { .id = UDP_LEN,   .len = 2, .offset = 4 },
  21         { .id = UDP_CSUM,  .len = 2, .offset = 6 },
  22 };
  23
  24 static void udp_header_init(struct proto_hdr *hdr)
  25 {
  26         proto_lower_default_add(hdr, PROTO_IP4);
  27
  28         proto_header_fields_add(hdr, udp_fields, array_size(udp_fields));
  29 }
  30
  31 static void udp_field_changed(struct proto_field *field)
  32 {
  33         field->hdr->is_csum_valid = false;
  34 }
  35
  36 static void udp_csum_update(struct proto_hdr *hdr)
  37 {
  38         struct proto_hdr *lower;
  39         uint16_t total_len;
  40         uint16_t csum;
  41
  42         if (hdr->is_csum_valid)
  43                 return;
  44         if (proto_hdr_field_is_set(hdr, UDP_CSUM))
  45                 return;
  46         lower = proto_lower_header(hdr);
  47         if (!lower)
  48                 return;
  49
  50         total_len = packet_get(hdr->pkt_id)->len - hdr->pkt_offset;
  51
  52         proto_hdr_field_set_default_be16(hdr, UDP_CSUM, 0);
  53
  54         switch (lower->ops->id) {
  55         case PROTO_IP4:
  56                 csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
  57                                 total_len, IPPROTO_UDP);
  58                 break;
  59         case PROTO_IP6:
  60                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
  61                                 total_len, IPPROTO_UDP);
  62                 break;
  63         default:
  64                 csum = 0;
  65                 break;
  66         }
  67
  68         proto_hdr_field_set_default_be16(hdr, UDP_CSUM, bswap_16(csum));
  69         hdr->is_csum_valid = true;
  70 }
  71
  72 static void udp_packet_finish(struct proto_hdr *hdr)
  73 {
  74         struct packet *pkt = proto_hdr_packet(hdr);
  75         uint16_t total_len;
  76
  77         total_len = pkt->len - hdr->pkt_offset;
  78         proto_hdr_field_set_default_be16(hdr, UDP_LEN, total_len);
  79
  80         udp_csum_update(hdr);
  81 }
  82
  83 static void udp_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  84 {
  85         uint16_t dport;
  86
  87         switch (pid) {
  88         case PROTO_DNS:
  89                 dport = 53;
  90                 break;
  91         default:
  92                 bug();
  93         }
  94
  95         proto_hdr_field_set_default_be16(hdr, UDP_DPORT, dport);
  96 }
  97
  98 static const struct proto_ops udp_proto_ops = {
  99         .id             = PROTO_UDP,
 100         .layer          = PROTO_L4,
 101         .header_init    = udp_header_init,
 102         .packet_update  = udp_csum_update,
 103         .packet_finish  = udp_packet_finish,
 104         .field_changed  = udp_field_changed,
 105         .set_next_proto = udp_set_next_proto,
 106 };
 107
 108 static struct proto_field tcp_fields[] = {
 109         { .id = TCP_SPORT,   .len = 2, .offset = 0 },
 110         { .id = TCP_DPORT,   .len = 2, .offset = 2 },
 111         { .id = TCP_SEQ,     .len = 4, .offset = 4 },
 112         { .id = TCP_ACK_SEQ, .len = 4, .offset = 8 },
 113         { .id = TCP_DOFF,    .len = 2, .offset = 12, .shift = 12, .mask = 0xf000 },
 114         /* reserved (4 bits) */
 115         { .id = TCP_CWR,     .len = 2, .offset = 12, .shift = 7, .mask = 0x0080 },
 116         { .id = TCP_ECE,     .len = 2, .offset = 12, .shift = 6, .mask = 0x0040 },
 117         { .id = TCP_URG,     .len = 2, .offset = 12, .shift = 5, .mask = 0x0020 },
 118         { .id = TCP_ACK,     .len = 2, .offset = 12, .shift = 4, .mask = 0x0010 },
 119         { .id = TCP_PSH,     .len = 2, .offset = 12, .shift = 3, .mask = 0x0008 },
 120         { .id = TCP_RST,     .len = 2, .offset = 12, .shift = 2, .mask = 0x0004 },
 121         { .id = TCP_SYN,     .len = 2, .offset = 12, .shift = 1, .mask = 0x0002 },
 122         { .id = TCP_FIN,     .len = 2, .offset = 12, .shift = 0, .mask = 0x0001 },
 123         { .id = TCP_WINDOW,  .len = 2, .offset = 14 },
 124         { .id = TCP_CSUM,    .len = 2, .offset = 16 },
 125         { .id = TCP_URG_PTR, .len = 2, .offset = 18 },
 126 };
 127
 128 static void tcp_header_init(struct proto_hdr *hdr)
 129 {
 130         proto_lower_default_add(hdr, PROTO_IP4);
 131
 132         proto_header_fields_add(hdr, tcp_fields, array_size(tcp_fields));
 133
 134         proto_hdr_field_set_default_be16(hdr, TCP_DOFF, 5);
 135 }
 136
 137 static void tcp_field_changed(struct proto_field *field)
 138 {
 139         field->hdr->is_csum_valid = false;
 140 }
 141
 142 static void tcp_csum_update(struct proto_hdr *hdr)
 143 {
 144         struct proto_hdr *lower = proto_lower_header(hdr);
 145         struct packet *pkt = proto_hdr_packet(hdr);
 146         uint16_t total_len;
 147         uint16_t csum;
 148
 149         if (hdr->is_csum_valid)
 150                 return;
 151         if (proto_hdr_field_is_set(hdr, TCP_CSUM))
 152                 return;
 153
 154         if (!lower)
 155                 return;
 156
 157         total_len = pkt->len - hdr->pkt_offset;
 158
 159         proto_hdr_field_set_default_be16(hdr, TCP_CSUM, 0);
 160
 161         switch (lower->ops->id) {
 162         case PROTO_IP4:
 163                 csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 164                                 total_len, IPPROTO_TCP);
 165                 break;
 166         case PROTO_IP6:
 167                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 168                                 total_len, IPPROTO_TCP);
 169                 break;
 170         default:
 171                 csum = 0;
 172                 break;
 173         }
 174
 175         proto_hdr_field_set_default_be16(hdr, TCP_CSUM, bswap_16(csum));
 176         hdr->is_csum_valid = true;
 177 }
 178
 179 static void tcp_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
 180 {
 181         uint16_t dport;
 182
 183         switch (pid) {
 184         case PROTO_DNS:
 185                 dport = 53;
 186                 break;
 187         default:
 188                 bug();
 189         }
 190
 191         proto_hdr_field_set_default_be16(hdr, TCP_DPORT, dport);
 192 }
 193
 194 static const struct proto_ops tcp_proto_ops = {
 195         .id             = PROTO_TCP,
 196         .layer          = PROTO_L4,
 197         .header_init    = tcp_header_init,
 198         .packet_update  = tcp_csum_update,
 199         .packet_finish  = tcp_csum_update,
 200         .field_changed  = tcp_field_changed,
 201         .set_next_proto = tcp_set_next_proto,
 202 };
 203
 204 static struct proto_field icmpv4_fields[] = {
 205         { .id = ICMPV4_TYPE,       .len = 1, .offset = 0 },
 206         { .id = ICMPV4_CODE,       .len = 1, .offset = 1 },
 207         { .id = ICMPV4_CSUM,       .len = 2, .offset = 2 },
 208         /* Echo/Ping fields */
 209         { .id = ICMPV4_ID,         .len = 2, .offset = 4 },
 210         { .id = ICMPV4_SEQ,        .len = 2, .offset = 6 },
 211         /* Redirect field */
 212         { .id = ICMPV4_REDIR_ADDR, .len = 4, .offset = 4 },
 213         /* Next-hop MTU */
 214         { .id = ICMPV4_MTU,        .len = 2, .offset = 6 },
 215 };
 216
 217 static void icmpv4_header_init(struct proto_hdr *hdr)
 218 {
 219         proto_lower_default_add(hdr, PROTO_IP4);
 220
 221         proto_header_fields_add(hdr, icmpv4_fields, array_size(icmpv4_fields));
 222 }
 223
 224 static void icmpv4_csum_update(struct proto_hdr *hdr)
 225 {
 226         struct packet *pkt;
 227         uint16_t csum;
 228
 229         if (hdr->is_csum_valid)
 230                 return;
 231         if (proto_hdr_field_is_set(hdr, ICMPV4_CSUM))
 232                 return;
 233
 234         pkt = packet_get(hdr->pkt_id);
 235
 236         proto_hdr_field_set_default_u16(hdr, ICMPV4_CSUM, 0);
 237         csum = htons(calc_csum(proto_header_ptr(hdr), pkt->len - hdr->pkt_offset));
 238         proto_hdr_field_set_default_u16(hdr, ICMPV4_CSUM, bswap_16(csum));
 239
 240         hdr->is_csum_valid = true;
 241 }
 242
 243 static void icmpv4_field_changed(struct proto_field *field)
 244 {
 245         field->hdr->is_csum_valid = false;
 246 }
 247
 248 static const struct proto_ops icmpv4_proto_ops = {
 249         .id             = PROTO_ICMP4,
 250         .layer          = PROTO_L4,
 251         .header_init    = icmpv4_header_init,
 252         .packet_update  = icmpv4_csum_update,
 253         .packet_finish  = icmpv4_csum_update,
 254         .field_changed  = icmpv4_field_changed,
 255 };
 256
 257 static struct proto_field icmpv6_fields[] = {
 258         { .id = ICMPV6_TYPE, .len = 1, .offset = 0 },
 259         { .id = ICMPV6_CODE, .len = 1, .offset = 1 },
 260         { .id = ICMPV6_CSUM, .len = 2, .offset = 2 }
 261 };
 262
 263 static void icmpv6_header_init(struct proto_hdr *hdr)
 264 {
 265         proto_lower_default_add(hdr, PROTO_IP6);
 266
 267         proto_header_fields_add(hdr, icmpv6_fields, array_size(icmpv6_fields));
 268 }
 269
 270 static void icmpv6_csum_update(struct proto_hdr *hdr)
 271 {
 272         struct proto_hdr *lower = proto_lower_header(hdr);
 273         struct packet *pkt = packet_get(hdr->pkt_id);
 274         uint16_t total_len;
 275         uint16_t csum;
 276
 277         if (unlikely(!lower))
 278                 return;
 279         if (hdr->is_csum_valid)
 280                 return;
 281         if (proto_hdr_field_is_set(hdr, ICMPV6_CSUM))
 282                 return;
 283
 284         total_len = pkt->len - hdr->pkt_offset;
 285
 286         proto_hdr_field_set_be16(hdr, ICMPV6_CSUM, 0);
 287
 288         if (likely(lower->ops->id == PROTO_IP6)) {
 289                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 290                                 total_len, IPPROTO_ICMPV6);
 291
 292                 proto_hdr_field_set_be16(hdr, ICMPV6_CSUM, bswap_16(csum));
 293                 hdr->is_csum_valid = true;
 294         }
 295 }
 296
 297 static void icmpv6_field_changed(struct proto_field *field)
 298 {
 299         field->hdr->is_csum_valid = false;
 300 }
 301
 302 static struct proto_ops icmpv6_proto_ops = {
 303         .id             = PROTO_ICMP6,
 304         .layer          = PROTO_L4,
 305         .header_init    = icmpv6_header_init,
 306         .packet_finish  = icmpv6_csum_update,
 307         .packet_update  = icmpv6_csum_update,
 308         .field_changed  = icmpv6_field_changed,
 309 };
 310
 311 void protos_l4_init(void)
 312 {
 313         proto_ops_register(&udp_proto_ops);
 314         proto_ops_register(&tcp_proto_ops);
 315         proto_ops_register(&icmpv4_proto_ops);
 316         proto_ops_register(&icmpv6_proto_ops);
 317 }