trafgen_l2.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Subject to the GPL, version 2.
   4  */
   5
   6 #include <net/if_arp.h>
   7 #include <linux/if_ether.h>
   8
   9 #include "built_in.h"
  10 #include "trafgen_l2.h"
  11 #include "trafgen_proto.h"
  12
  13 static struct proto_field eth_fields[] = {
  14         { .id = ETH_DST_ADDR, .len = 6, },
  15         { .id = ETH_SRC_ADDR, .len = 6, .offset = 6 },
  16         { .id = ETH_TYPE,     .len = 2, .offset = 12 },
  17 };
  18
  19 static void eth_header_init(struct proto_hdr *hdr)
  20 {
  21         proto_header_fields_add(hdr, eth_fields, array_size(eth_fields));
  22
  23         proto_field_set_default_dev_mac(hdr, ETH_SRC_ADDR);
  24 }
  25
  26 static struct proto_hdr eth_hdr = {
  27         .id             = PROTO_ETH,
  28         .layer          = PROTO_L2,
  29         .header_init    = eth_header_init,
  30 };
  31
  32 static struct proto_field arp_fields[] = {
  33         { .id = ARP_HTYPE, .len = 2 },
  34         { .id = ARP_PTYPE, .len = 2, .offset = 2 },
  35         { .id = ARP_HLEN,  .len = 1, .offset = 4 },
  36         { .id = ARP_PLEN,  .len = 1, .offset = 5 },
  37         { .id = ARP_OPER,  .len = 2, .offset = 6 },
  38         { .id = ARP_SHA,   .len = 6, .offset = 8 },
  39         { .id = ARP_SPA,   .len = 4, .offset = 14 },
  40         { .id = ARP_THA,   .len = 6, .offset = 18 },
  41         { .id = ARP_TPA,   .len = 4, .offset = 24 },
  42 };
  43
  44 static void arp_header_init(struct proto_hdr *hdr)
  45 {
  46         struct proto_hdr *lower;
  47
  48         lower = proto_lower_default_add(hdr, PROTO_ETH);
  49
  50         if (lower->id == PROTO_ETH) {
  51                 uint8_t bcast[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  52
  53                 proto_field_set_default_bytes(lower, ETH_DST_ADDR, bcast);
  54                 proto_field_set_default_be16(lower, ETH_TYPE, ETH_P_ARP);
  55         }
  56
  57         proto_header_fields_add(hdr, arp_fields, array_size(arp_fields));
  58
  59         /* Generate Announce request by default */
  60         proto_field_set_default_be16(hdr, ARP_HTYPE, ARPHRD_ETHER);
  61         proto_field_set_default_be16(hdr, ARP_PTYPE, ETH_P_IP);
  62         proto_field_set_default_u8(hdr, ARP_HLEN, 6);
  63         proto_field_set_default_u8(hdr, ARP_PLEN, 4);
  64         proto_field_set_default_be16(hdr, ARP_OPER, ARPOP_REQUEST);
  65         proto_field_set_default_dev_mac(hdr, ARP_SHA);
  66         proto_field_set_default_dev_ipv4(hdr, ARP_SPA);
  67         proto_field_set_default_dev_ipv4(hdr, ARP_TPA);
  68 }
  69
  70 static struct proto_hdr arp_hdr = {
  71         .id             = PROTO_ARP,
  72         .layer          = PROTO_L2,
  73         .header_init    = arp_header_init,
  74 };
  75
  76 void protos_l2_init(void)
  77 {
  78         proto_header_register(&eth_hdr);
  79         proto_header_register(&arp_hdr);
  80 }