proto_vlan.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2009, 2010 Daniel Borkmann.
   4  * Copyright 2010 Emmanuel Roullit.
   5  * Subject to the GPL, version 2.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdint.h>
  10 #include <netinet/in.h>    /* for ntohs() */
  11
  12 #include "proto.h"
  13 #include "dissector_eth.h"
  14 #include "pkt_buff.h"
  15
  16 struct vlanhdr {
  17         uint16_t h_vlan_TCI;
  18         uint16_t h_vlan_encapsulated_proto;
  19 } __packed;
  20
  21 static void vlan(struct pkt_buff *pkt)
  22 {
  23         uint16_t tci;
  24         struct vlanhdr *vlan = (struct vlanhdr *) pkt_pull(pkt, sizeof(*vlan));
  25
  26         if (vlan == NULL)
  27                 return;
  28
  29         tci = ntohs(vlan->h_vlan_TCI);
  30
  31         tprintf(" [ VLAN ");
  32         tprintf("Prio (%d), ", (tci & 0xE000) >> 13);
  33         tprintf("CFI (%d), ", (tci & 0x1000) >> 12);
  34         tprintf("ID (%d), ", (tci & 0x0FFF));
  35         tprintf("Proto (0x%.4x)", ntohs(vlan->h_vlan_encapsulated_proto));
  36         tprintf(" ]\n");
  37
  38         pkt_set_proto(pkt, &eth_lay2, ntohs(vlan->h_vlan_encapsulated_proto));
  39 }
  40
  41 static void vlan_less(struct pkt_buff *pkt)
  42 {
  43         uint16_t tci;
  44         struct vlanhdr *vlan = (struct vlanhdr *) pkt_pull(pkt, sizeof(*vlan));
  45
  46         if (vlan == NULL)
  47                 return;
  48
  49         tci = ntohs(vlan->h_vlan_TCI);
  50
  51         tprintf(" VLAN%d", (tci & 0x0FFF));
  52
  53         pkt_set_proto(pkt, &eth_lay2, ntohs(vlan->h_vlan_encapsulated_proto));
  54 }
  55
  56 struct protocol vlan_ops = {
  57         .key = 0x8100,
  58         .print_full = vlan,
  59         .print_less = vlan_less,
  60 };