proto_vlan.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2009, 2010 Daniel Borkmann.
   5  * Copyright 2010 Emmanuel Roullit.
   6  * Subject to the GPL, version 2.
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdint.h>
  11 #include <netinet/in.h>    /* for ntohs() */
  12
  13 #include "proto.h"
  14 #include "protos.h"
  15 #include "dissector_eth.h"
  16 #include "pkt_buff.h"
  17
  18 struct vlanhdr {
  19         uint16_t h_vlan_TCI;
  20         uint16_t h_vlan_encapsulated_proto;
  21 } __attribute__((packed));
  22
  23 static void vlan(struct pkt_buff *pkt)
  24 {
  25         uint16_t tci;
  26         struct vlanhdr *vlan = (struct vlanhdr *) pkt_pull(pkt, sizeof(*vlan));
  27
  28         if (vlan == NULL)
  29                 return;
  30
  31         tci = ntohs(vlan->h_vlan_TCI);
  32
  33         tprintf(" [ VLAN ");
  34         tprintf("Prio (%d), ", (tci & 0xE000) >> 13);
  35         tprintf("CFI (%d), ", (tci & 0x1000) >> 12);
  36         tprintf("ID (%d), ", (tci & 0x0FFF));
  37         tprintf("Proto (0x%.4x)", ntohs(vlan->h_vlan_encapsulated_proto));
  38         tprintf(" ]\n");
  39
  40         pkt_set_proto(pkt, &eth_lay2, ntohs(vlan->h_vlan_encapsulated_proto));
  41 }
  42
  43 static void vlan_less(struct pkt_buff *pkt)
  44 {
  45         uint16_t tci;
  46         struct vlanhdr *vlan = (struct vlanhdr *) pkt_pull(pkt, sizeof(*vlan));
  47
  48         if (vlan == NULL)
  49                 return;
  50
  51         tci = ntohs(vlan->h_vlan_TCI);
  52
  53         tprintf(" VLAN%d", (tci & 0x0FFF));
  54
  55         pkt_set_proto(pkt, &eth_lay2, ntohs(vlan->h_vlan_encapsulated_proto));
  56 }
  57
  58 struct protocol vlan_ops = {
  59         .key = 0x8100,
  60         .print_full = vlan,
  61         .print_less = vlan_less,
  62 };