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 "die.h"
  10 #include "built_in.h"
  11 #include "trafgen_l2.h"
  12 #include "trafgen_proto.h"
  13
  14 static struct proto_field eth_fields[] = {
  15         { .id = ETH_DST_ADDR, .len = 6, },
  16         { .id = ETH_SRC_ADDR, .len = 6, .offset = 6 },
  17         { .id = ETH_TYPE,     .len = 2, .offset = 12 },
  18 };
  19
  20 static void eth_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  21 {
  22         uint16_t eth_type;
  23
  24         switch(pid) {
  25         case PROTO_ARP:
  26                 eth_type = ETH_P_ARP;
  27                 break;
  28         case PROTO_IP4:
  29                 eth_type = ETH_P_IP;
  30                 break;
  31         case PROTO_IP6:
  32                 eth_type = ETH_P_IPV6;
  33                 break;
  34         default:
  35                 panic("eth: Not supported protocol id %u\n", pid);
  36         }
  37
  38         proto_field_set_default_be16(hdr, ETH_TYPE, eth_type);
  39 }
  40
  41 static void eth_header_init(struct proto_hdr *hdr)
  42 {
  43         proto_header_fields_add(hdr, eth_fields, array_size(eth_fields));
  44
  45         proto_field_set_default_dev_mac(hdr, ETH_SRC_ADDR);
  46 }
  47
  48 static struct proto_hdr eth_hdr = {
  49         .id             = PROTO_ETH,
  50         .layer          = PROTO_L2,
  51         .header_init    = eth_header_init,
  52         .set_next_proto = eth_set_next_proto,
  53 };
  54
  55 static struct proto_field arp_fields[] = {
  56         { .id = ARP_HTYPE, .len = 2 },
  57         { .id = ARP_PTYPE, .len = 2, .offset = 2 },
  58         { .id = ARP_HLEN,  .len = 1, .offset = 4 },
  59         { .id = ARP_PLEN,  .len = 1, .offset = 5 },
  60         { .id = ARP_OPER,  .len = 2, .offset = 6 },
  61         { .id = ARP_SHA,   .len = 6, .offset = 8 },
  62         { .id = ARP_SPA,   .len = 4, .offset = 14 },
  63         { .id = ARP_THA,   .len = 6, .offset = 18 },
  64         { .id = ARP_TPA,   .len = 4, .offset = 24 },
  65 };
  66
  67 static void arp_header_init(struct proto_hdr *hdr)
  68 {
  69         struct proto_hdr *lower;
  70
  71         lower = proto_lower_default_add(hdr, PROTO_ETH);
  72
  73         if (lower->id == PROTO_ETH) {
  74                 uint8_t bcast[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  75
  76                 proto_field_set_default_bytes(lower, ETH_DST_ADDR, bcast);
  77         }
  78
  79         proto_header_fields_add(hdr, arp_fields, array_size(arp_fields));
  80
  81         /* Generate Announce request by default */
  82         proto_field_set_default_be16(hdr, ARP_HTYPE, ARPHRD_ETHER);
  83         proto_field_set_default_be16(hdr, ARP_PTYPE, ETH_P_IP);
  84         proto_field_set_default_u8(hdr, ARP_HLEN, 6);
  85         proto_field_set_default_u8(hdr, ARP_PLEN, 4);
  86         proto_field_set_default_be16(hdr, ARP_OPER, ARPOP_REQUEST);
  87         proto_field_set_default_dev_mac(hdr, ARP_SHA);
  88         proto_field_set_default_dev_ipv4(hdr, ARP_SPA);
  89         proto_field_set_default_dev_ipv4(hdr, ARP_TPA);
  90 }
  91
  92 static struct proto_hdr arp_hdr = {
  93         .id             = PROTO_ARP,
  94         .layer          = PROTO_L2,
  95         .header_init    = arp_header_init,
  96 };
  97
  98 void protos_l2_init(void)
  99 {
 100         proto_header_register(&eth_hdr);
 101         proto_header_register(&arp_hdr);
 102 }