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 uint16_t pid_to_eth(enum proto_id pid)
  21 {
  22         switch(pid) {
  23         case PROTO_ARP:
  24                 return ETH_P_ARP;
  25         case PROTO_IP4:
  26                 return ETH_P_IP;
  27         case PROTO_IP6:
  28                 return ETH_P_IPV6;
  29         case PROTO_VLAN:
  30                 return ETH_P_8021Q;
  31         default:
  32                 panic("eth: Not supported protocol id %u\n", pid);
  33         }
  34 }
  35
  36 static void eth_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  37 {
  38         proto_field_set_default_be16(hdr, ETH_TYPE, pid_to_eth(pid));
  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 vlan_fields[] = {
  56         /* TPID overlaps with Ethernet header and points to ether type */
  57         { .id = VLAN_TPID, .len = 2, .offset = -2 },
  58         { .id = VLAN_TCI,  .len = 2, .offset = 0 },
  59         { .id = VLAN_PCP,  .len = 2, .offset = 0, .shift = 13, .mask = 0xe000 },
  60         { .id = VLAN_DEI,  .len = 2, .offset = 0, .shift = 12, .mask = 0x1000 },
  61         { .id = VLAN_VID,  .len = 2, .offset = 0, .shift = 0,  .mask = 0xfff },
  62         /* Original ether type is stored after VLAN header */
  63         { .id = VLAN_ETYPE, .len = 2, .offset = 2 },
  64 };
  65
  66 static void vlan_header_init(struct proto_hdr *hdr)
  67 {
  68         struct proto_hdr *lower;
  69         uint16_t lower_etype = 0;
  70
  71         lower = proto_lower_default_add(hdr, PROTO_ETH);
  72
  73         proto_header_fields_add(hdr, vlan_fields, array_size(vlan_fields));
  74
  75         if (lower->id == PROTO_ETH)
  76                 lower_etype = proto_field_get_u16(lower, ETH_TYPE);
  77         else if (lower->id == PROTO_VLAN)
  78                 lower_etype = proto_field_get_u16(lower, VLAN_ETYPE);
  79
  80         proto_field_set_be16(hdr, VLAN_ETYPE, lower_etype);
  81         proto_field_set_default_be16(hdr, VLAN_TPID, pid_to_eth(hdr->id));
  82 }
  83
  84 static void vlan_set_next_proto(struct proto_hdr *hdr, enum proto_id pid)
  85 {
  86         if (pid != PROTO_VLAN)
  87                 proto_field_set_be16(hdr, VLAN_ETYPE, pid_to_eth(pid));
  88 }
  89
  90 static struct proto_hdr vlan_hdr = {
  91         .id             = PROTO_VLAN,
  92         .layer          = PROTO_L2,
  93         .header_init    = vlan_header_init,
  94         .set_next_proto = vlan_set_next_proto,
  95 };
  96
  97 static struct proto_field arp_fields[] = {
  98         { .id = ARP_HTYPE, .len = 2 },
  99         { .id = ARP_PTYPE, .len = 2, .offset = 2 },
 100         { .id = ARP_HLEN,  .len = 1, .offset = 4 },
 101         { .id = ARP_PLEN,  .len = 1, .offset = 5 },
 102         { .id = ARP_OPER,  .len = 2, .offset = 6 },
 103         { .id = ARP_SHA,   .len = 6, .offset = 8 },
 104         { .id = ARP_SPA,   .len = 4, .offset = 14 },
 105         { .id = ARP_THA,   .len = 6, .offset = 18 },
 106         { .id = ARP_TPA,   .len = 4, .offset = 24 },
 107 };
 108
 109 static void arp_header_init(struct proto_hdr *hdr)
 110 {
 111         struct proto_hdr *lower;
 112
 113         lower = proto_lower_default_add(hdr, PROTO_ETH);
 114
 115         if (lower->id == PROTO_ETH) {
 116                 uint8_t bcast[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 117
 118                 proto_field_set_default_bytes(lower, ETH_DST_ADDR, bcast);
 119         }
 120
 121         proto_header_fields_add(hdr, arp_fields, array_size(arp_fields));
 122
 123         /* Generate Announce request by default */
 124         proto_field_set_default_be16(hdr, ARP_HTYPE, ARPHRD_ETHER);
 125         proto_field_set_default_be16(hdr, ARP_PTYPE, ETH_P_IP);
 126         proto_field_set_default_u8(hdr, ARP_HLEN, 6);
 127         proto_field_set_default_u8(hdr, ARP_PLEN, 4);
 128         proto_field_set_default_be16(hdr, ARP_OPER, ARPOP_REQUEST);
 129         proto_field_set_default_dev_mac(hdr, ARP_SHA);
 130         proto_field_set_default_dev_ipv4(hdr, ARP_SPA);
 131         proto_field_set_default_dev_ipv4(hdr, ARP_TPA);
 132 }
 133
 134 static struct proto_hdr arp_hdr = {
 135         .id             = PROTO_ARP,
 136         .layer          = PROTO_L2,
 137         .header_init    = arp_header_init,
 138 };
 139
 140 void protos_l2_init(void)
 141 {
 142         proto_header_register(&eth_hdr);
 143         proto_header_register(&vlan_hdr);
 144         proto_header_register(&arp_hdr);
 145 }