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 = current_packet();
  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 const struct proto_ops udp_proto_ops = {
  84         .id             = PROTO_UDP,
  85         .layer          = PROTO_L4,
  86         .header_init    = udp_header_init,
  87         .packet_update  = udp_csum_update,
  88         .packet_finish  = udp_packet_finish,
  89         .field_changed  = udp_field_changed,
  90 };
  91
  92 static struct proto_field tcp_fields[] = {
  93         { .id = TCP_SPORT,   .len = 2, .offset = 0 },
  94         { .id = TCP_DPORT,   .len = 2, .offset = 2 },
  95         { .id = TCP_SEQ,     .len = 4, .offset = 4 },
  96         { .id = TCP_ACK_SEQ, .len = 4, .offset = 8 },
  97         { .id = TCP_DOFF,    .len = 2, .offset = 12, .shift = 12, .mask = 0xf000 },
  98         /* reserved (4 bits) */
  99         { .id = TCP_CWR,     .len = 2, .offset = 12, .shift = 7, .mask = 0x0080 },
 100         { .id = TCP_ECE,     .len = 2, .offset = 12, .shift = 6, .mask = 0x0040 },
 101         { .id = TCP_URG,     .len = 2, .offset = 12, .shift = 5, .mask = 0x0020 },
 102         { .id = TCP_ACK,     .len = 2, .offset = 12, .shift = 4, .mask = 0x0010 },
 103         { .id = TCP_PSH,     .len = 2, .offset = 12, .shift = 3, .mask = 0x0008 },
 104         { .id = TCP_RST,     .len = 2, .offset = 12, .shift = 2, .mask = 0x0004 },
 105         { .id = TCP_SYN,     .len = 2, .offset = 12, .shift = 1, .mask = 0x0002 },
 106         { .id = TCP_FIN,     .len = 2, .offset = 12, .shift = 0, .mask = 0x0001 },
 107         { .id = TCP_WINDOW,  .len = 2, .offset = 14 },
 108         { .id = TCP_CSUM,    .len = 2, .offset = 16 },
 109         { .id = TCP_URG_PTR, .len = 2, .offset = 18 },
 110 };
 111
 112 static void tcp_header_init(struct proto_hdr *hdr)
 113 {
 114         proto_lower_default_add(hdr, PROTO_IP4);
 115
 116         proto_header_fields_add(hdr, tcp_fields, array_size(tcp_fields));
 117
 118         proto_hdr_field_set_default_be16(hdr, TCP_DOFF, 5);
 119 }
 120
 121 static void tcp_field_changed(struct proto_field *field)
 122 {
 123         field->hdr->is_csum_valid = false;
 124 }
 125
 126 static void tcp_csum_update(struct proto_hdr *hdr)
 127 {
 128         struct proto_hdr *lower = proto_lower_header(hdr);
 129         struct packet *pkt = current_packet();
 130         uint16_t total_len;
 131         uint16_t csum;
 132
 133         if (hdr->is_csum_valid)
 134                 return;
 135         if (proto_hdr_field_is_set(hdr, TCP_CSUM))
 136                 return;
 137
 138         if (!lower)
 139                 return;
 140
 141         total_len = pkt->len - hdr->pkt_offset;
 142
 143         proto_hdr_field_set_default_be16(hdr, TCP_CSUM, 0);
 144
 145         switch (lower->ops->id) {
 146         case PROTO_IP4:
 147                 csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 148                                 total_len, IPPROTO_TCP);
 149                 break;
 150         case PROTO_IP6:
 151                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 152                                 total_len, IPPROTO_TCP);
 153                 break;
 154         default:
 155                 csum = 0;
 156                 break;
 157         }
 158
 159         proto_hdr_field_set_default_be16(hdr, TCP_CSUM, bswap_16(csum));
 160         hdr->is_csum_valid = true;
 161 }
 162
 163 static const struct proto_ops tcp_proto_ops = {
 164         .id             = PROTO_TCP,
 165         .layer          = PROTO_L4,
 166         .header_init    = tcp_header_init,
 167         .packet_update  = tcp_csum_update,
 168         .packet_finish  = tcp_csum_update,
 169         .field_changed  = tcp_field_changed,
 170 };
 171
 172 static struct proto_field icmpv4_fields[] = {
 173         { .id = ICMPV4_TYPE,       .len = 1, .offset = 0 },
 174         { .id = ICMPV4_CODE,       .len = 1, .offset = 1 },
 175         { .id = ICMPV4_CSUM,       .len = 2, .offset = 2 },
 176         /* Echo/Ping fields */
 177         { .id = ICMPV4_ID,         .len = 2, .offset = 4 },
 178         { .id = ICMPV4_SEQ,        .len = 2, .offset = 6 },
 179         /* Redirect field */
 180         { .id = ICMPV4_REDIR_ADDR, .len = 4, .offset = 4 },
 181         /* Next-hop MTU */
 182         { .id = ICMPV4_MTU,        .len = 2, .offset = 6 },
 183 };
 184
 185 static void icmpv4_header_init(struct proto_hdr *hdr)
 186 {
 187         proto_lower_default_add(hdr, PROTO_IP4);
 188
 189         proto_header_fields_add(hdr, icmpv4_fields, array_size(icmpv4_fields));
 190 }
 191
 192 static void icmpv4_csum_update(struct proto_hdr *hdr)
 193 {
 194         struct packet *pkt;
 195         uint16_t csum;
 196
 197         if (hdr->is_csum_valid)
 198                 return;
 199         if (proto_hdr_field_is_set(hdr, ICMPV4_CSUM))
 200                 return;
 201
 202         pkt = packet_get(hdr->pkt_id);
 203
 204         proto_hdr_field_set_default_u16(hdr, ICMPV4_CSUM, 0);
 205         csum = htons(calc_csum(proto_header_ptr(hdr), pkt->len - hdr->pkt_offset));
 206         proto_hdr_field_set_default_u16(hdr, ICMPV4_CSUM, bswap_16(csum));
 207
 208         hdr->is_csum_valid = true;
 209 }
 210
 211 static void icmpv4_field_changed(struct proto_field *field)
 212 {
 213         field->hdr->is_csum_valid = false;
 214 }
 215
 216 static const struct proto_ops icmpv4_proto_ops = {
 217         .id             = PROTO_ICMP4,
 218         .layer          = PROTO_L4,
 219         .header_init    = icmpv4_header_init,
 220         .packet_update  = icmpv4_csum_update,
 221         .packet_finish  = icmpv4_csum_update,
 222         .field_changed  = icmpv4_field_changed,
 223 };
 224
 225 static struct proto_field icmpv6_fields[] = {
 226         { .id = ICMPV6_TYPE, .len = 1, .offset = 0 },
 227         { .id = ICMPV6_CODE, .len = 1, .offset = 1 },
 228         { .id = ICMPV6_CSUM, .len = 2, .offset = 2 }
 229 };
 230
 231 static void icmpv6_header_init(struct proto_hdr *hdr)
 232 {
 233         proto_lower_default_add(hdr, PROTO_IP6);
 234
 235         proto_header_fields_add(hdr, icmpv6_fields, array_size(icmpv6_fields));
 236 }
 237
 238 static void icmpv6_csum_update(struct proto_hdr *hdr)
 239 {
 240         struct proto_hdr *lower = proto_lower_header(hdr);
 241         struct packet *pkt = packet_get(hdr->pkt_id);
 242         uint16_t total_len;
 243         uint16_t csum;
 244
 245         if (unlikely(!lower))
 246                 return;
 247         if (hdr->is_csum_valid)
 248                 return;
 249         if (proto_hdr_field_is_set(hdr, ICMPV6_CSUM))
 250                 return;
 251
 252         total_len = pkt->len - hdr->pkt_offset;
 253
 254         proto_hdr_field_set_be16(hdr, ICMPV6_CSUM, 0);
 255
 256         if (likely(lower->ops->id == PROTO_IP6)) {
 257                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 258                                 total_len, IPPROTO_ICMPV6);
 259
 260                 proto_hdr_field_set_be16(hdr, ICMPV6_CSUM, bswap_16(csum));
 261                 hdr->is_csum_valid = true;
 262         }
 263 }
 264
 265 static void icmpv6_field_changed(struct proto_field *field)
 266 {
 267         field->hdr->is_csum_valid = false;
 268 }
 269
 270 static struct proto_ops icmpv6_proto_ops = {
 271         .id             = PROTO_ICMP6,
 272         .layer          = PROTO_L4,
 273         .header_init    = icmpv6_header_init,
 274         .packet_finish  = icmpv6_csum_update,
 275         .packet_update  = icmpv6_csum_update,
 276         .field_changed  = icmpv6_field_changed,
 277 };
 278
 279 void protos_l4_init(void)
 280 {
 281         proto_ops_register(&udp_proto_ops);
 282         proto_ops_register(&tcp_proto_ops);
 283         proto_ops_register(&icmpv4_proto_ops);
 284         proto_ops_register(&icmpv6_proto_ops);
 285 }