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_packet_finish(struct proto_hdr *hdr)
  32 {
  33         struct proto_hdr *lower = proto_lower_header(hdr);
  34         struct packet *pkt = current_packet();
  35         uint16_t total_len;
  36         uint16_t csum;
  37
  38         total_len = pkt->len - hdr->pkt_offset;
  39         proto_field_set_default_be16(hdr, UDP_LEN, total_len);
  40
  41         if (proto_field_is_set(hdr, UDP_CSUM))
  42                 return;
  43
  44         if (!lower)
  45                 return;
  46
  47         switch (lower->ops->id) {
  48         case PROTO_IP4:
  49                 csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
  50                                 total_len, IPPROTO_UDP);
  51                 break;
  52         case PROTO_IP6:
  53                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
  54                                 total_len, IPPROTO_UDP);
  55                 break;
  56         default:
  57                 csum = 0;
  58                 break;
  59         }
  60
  61         proto_field_set_be16(hdr, UDP_CSUM, bswap_16(csum));
  62 }
  63
  64 static const struct proto_ops udp_proto_ops = {
  65         .id             = PROTO_UDP,
  66         .layer          = PROTO_L4,
  67         .header_init    = udp_header_init,
  68         .packet_finish  = udp_packet_finish,
  69 };
  70
  71 static struct proto_field tcp_fields[] = {
  72         { .id = TCP_SPORT,   .len = 2, .offset = 0 },
  73         { .id = TCP_DPORT,   .len = 2, .offset = 2 },
  74         { .id = TCP_SEQ,     .len = 4, .offset = 4 },
  75         { .id = TCP_ACK_SEQ, .len = 4, .offset = 8 },
  76         { .id = TCP_DOFF,    .len = 2, .offset = 12, .shift = 12, .mask = 0xf000 },
  77         /* reserved (4 bits) */
  78         { .id = TCP_CWR,     .len = 2, .offset = 12, .shift = 7, .mask = 0x0080 },
  79         { .id = TCP_ECE,     .len = 2, .offset = 12, .shift = 6, .mask = 0x0040 },
  80         { .id = TCP_URG,     .len = 2, .offset = 12, .shift = 5, .mask = 0x0020 },
  81         { .id = TCP_ACK,     .len = 2, .offset = 12, .shift = 4, .mask = 0x0010 },
  82         { .id = TCP_PSH,     .len = 2, .offset = 12, .shift = 3, .mask = 0x0008 },
  83         { .id = TCP_RST,     .len = 2, .offset = 12, .shift = 2, .mask = 0x0004 },
  84         { .id = TCP_SYN,     .len = 2, .offset = 12, .shift = 1, .mask = 0x0002 },
  85         { .id = TCP_FIN,     .len = 2, .offset = 12, .shift = 0, .mask = 0x0001 },
  86         { .id = TCP_WINDOW,  .len = 2, .offset = 14 },
  87         { .id = TCP_CSUM,    .len = 2, .offset = 16 },
  88         { .id = TCP_URG_PTR, .len = 2, .offset = 18 },
  89 };
  90
  91 static void tcp_header_init(struct proto_hdr *hdr)
  92 {
  93         proto_lower_default_add(hdr, PROTO_IP4);
  94
  95         proto_header_fields_add(hdr, tcp_fields, array_size(tcp_fields));
  96
  97         proto_field_set_default_be16(hdr, TCP_DOFF, 5);
  98 }
  99
 100 static void tcp_packet_finish(struct proto_hdr *hdr)
 101 {
 102         struct proto_hdr *lower = proto_lower_header(hdr);
 103         struct packet *pkt = current_packet();
 104         uint16_t total_len;
 105         uint16_t csum;
 106
 107         if (proto_field_is_set(hdr, TCP_CSUM))
 108                 return;
 109
 110         if (!lower)
 111                 return;
 112
 113         total_len = pkt->len - hdr->pkt_offset;
 114
 115         switch (lower->ops->id) {
 116         case PROTO_IP4:
 117                 csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 118                                 total_len, IPPROTO_TCP);
 119                 break;
 120         case PROTO_IP6:
 121                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 122                                 total_len, IPPROTO_TCP);
 123                 break;
 124         default:
 125                 csum = 0;
 126                 break;
 127         }
 128
 129         proto_field_set_be16(hdr, TCP_CSUM, bswap_16(csum));
 130 }
 131
 132 static const struct proto_ops tcp_proto_ops = {
 133         .id             = PROTO_TCP,
 134         .layer          = PROTO_L4,
 135         .header_init    = tcp_header_init,
 136         .packet_finish  = tcp_packet_finish,
 137 };
 138
 139 static struct proto_field icmpv4_fields[] = {
 140         { .id = ICMPV4_TYPE,       .len = 1, .offset = 0 },
 141         { .id = ICMPV4_CODE,       .len = 1, .offset = 1 },
 142         { .id = ICMPV4_CSUM,       .len = 2, .offset = 2 },
 143         /* Echo/Ping fields */
 144         { .id = ICMPV4_ID,         .len = 2, .offset = 4 },
 145         { .id = ICMPV4_SEQ,        .len = 2, .offset = 6 },
 146         /* Redirect field */
 147         { .id = ICMPV4_REDIR_ADDR, .len = 4, .offset = 4 },
 148         /* Next-hop MTU */
 149         { .id = ICMPV4_MTU,        .len = 2, .offset = 6 },
 150 };
 151
 152 static void icmpv4_header_init(struct proto_hdr *hdr)
 153 {
 154         proto_lower_default_add(hdr, PROTO_IP4);
 155
 156         proto_header_fields_add(hdr, icmpv4_fields, array_size(icmpv4_fields));
 157 }
 158
 159 static void icmpv4_csum_update(struct proto_hdr *hdr)
 160 {
 161         struct packet *pkt;
 162         uint16_t csum;
 163
 164         if (hdr->is_csum_valid)
 165                 return;
 166         if (proto_field_is_set(hdr, ICMPV4_CSUM))
 167                 return;
 168
 169         pkt = packet_get(hdr->pkt_id);
 170
 171         proto_field_set_default_u16(hdr, ICMPV4_CSUM, 0);
 172         csum = htons(calc_csum(proto_header_ptr(hdr), pkt->len - hdr->pkt_offset));
 173         proto_field_set_default_u16(hdr, ICMPV4_CSUM, bswap_16(csum));
 174
 175         hdr->is_csum_valid = true;
 176 }
 177
 178 static void icmpv4_field_changed(struct proto_field *field)
 179 {
 180         field->hdr->is_csum_valid = false;
 181 }
 182
 183 static const struct proto_ops icmpv4_proto_ops = {
 184         .id             = PROTO_ICMP4,
 185         .layer          = PROTO_L4,
 186         .header_init    = icmpv4_header_init,
 187         .packet_update  = icmpv4_csum_update,
 188         .packet_finish  = icmpv4_csum_update,
 189         .field_changed  = icmpv4_field_changed,
 190 };
 191
 192 static struct proto_field icmpv6_fields[] = {
 193         { .id = ICMPV6_TYPE, .len = 1, .offset = 0 },
 194         { .id = ICMPV6_CODE, .len = 1, .offset = 1 },
 195         { .id = ICMPV6_CSUM, .len = 2, .offset = 2 }
 196 };
 197
 198 static void icmpv6_header_init(struct proto_hdr *hdr)
 199 {
 200         proto_lower_default_add(hdr, PROTO_IP6);
 201
 202         proto_header_fields_add(hdr, icmpv6_fields, array_size(icmpv6_fields));
 203 }
 204
 205 static void icmpv6_packet_finish(struct proto_hdr *hdr)
 206 {
 207         struct proto_hdr *lower = proto_lower_header(hdr);
 208         struct packet *pkt = current_packet();
 209         uint16_t total_len;
 210         uint16_t csum;
 211
 212         if (proto_field_is_set(hdr, ICMPV6_CSUM))
 213                 return;
 214
 215         if (!lower)
 216                 return;
 217
 218         total_len = pkt->len - hdr->pkt_offset;
 219
 220         switch (lower->ops->id) {
 221         case PROTO_IP6:
 222                 csum = p6_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
 223                                 total_len, IPPROTO_ICMPV6);
 224                 break;
 225         default:
 226                 csum = 0;
 227                 break;
 228         }
 229
 230         proto_field_set_be16(hdr, ICMPV6_CSUM, bswap_16(csum));
 231 }
 232
 233 static struct proto_ops icmpv6_proto_ops = {
 234         .id             = PROTO_ICMP6,
 235         .layer          = PROTO_L4,
 236         .header_init    = icmpv6_header_init,
 237         .packet_finish  = icmpv6_packet_finish,
 238 };
 239
 240 void protos_l4_init(void)
 241 {
 242         proto_ops_register(&udp_proto_ops);
 243         proto_ops_register(&tcp_proto_ops);
 244         proto_ops_register(&icmpv4_proto_ops);
 245         proto_ops_register(&icmpv6_proto_ops);
 246 }