proto_udp.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2009, 2010 Daniel Borkmann.
   4  * Subject to the GPL, version 2.
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdint.h>
   9 #include <netinet/in.h>    /* for ntohs() */
  10
  11 #include "proto.h"
  12 #include "protos.h"
  13 #include "dissector_eth.h"
  14 #include "pkt_buff.h"
  15
  16 struct udphdr {
  17         uint16_t source;
  18         uint16_t dest;
  19         uint16_t len;
  20         uint16_t check;
  21 } __packed;
  22
  23 static void udp(struct pkt_buff *pkt)
  24 {
  25         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  26         ssize_t len;
  27         uint16_t src, dest;
  28         char *src_name, *dest_name;
  29
  30         if (udp == NULL)
  31                 return;
  32
  33         len = ntohs(udp->len) - sizeof(*udp);
  34         src = ntohs(udp->source);
  35         dest = ntohs(udp->dest);
  36
  37         src_name = lookup_port_udp(src);
  38         dest_name = lookup_port_udp(dest);
  39
  40         tprintf(" [ UDP ");
  41         tprintf("Port (%u", src);
  42         if (src_name)
  43                 tprintf(" (%s%s%s)", colorize_start(bold), src_name,
  44                         colorize_end());
  45         tprintf(" => %u", dest);
  46         if (dest_name)
  47                 tprintf(" (%s%s%s)", colorize_start(bold), dest_name,
  48                         colorize_end());
  49         tprintf("), ");
  50         if(len > pkt_len(pkt) || len < 0){
  51                 tprintf("Len (%u) %s, ", ntohs(udp->len),
  52                         colorize_start_full(black, red)
  53                         "invalid" colorize_end());
  54         }
  55         tprintf("Len (%u Bytes, %zd Bytes Data), ", ntohs(udp->len), len);
  56         tprintf("CSum (0x%.4x)", ntohs(udp->check));
  57         tprintf(" ]\n");
  58 }
  59
  60 static void udp_less(struct pkt_buff *pkt)
  61 {
  62         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  63         uint16_t src, dest;
  64         char *src_name, *dest_name;
  65
  66         if (udp == NULL)
  67                 return;
  68
  69         src = ntohs(udp->source);
  70         dest = ntohs(udp->dest);
  71
  72         src_name = lookup_port_udp(src);
  73         dest_name = lookup_port_udp(dest);
  74
  75         tprintf(" UDP %u", src);
  76         if(src_name)
  77                 tprintf("(%s%s%s)", colorize_start(bold), src_name,
  78                         colorize_end());
  79         tprintf("/%u", dest);
  80         if (dest_name)
  81                 tprintf("(%s%s%s)", colorize_start(bold), dest_name,
  82                         colorize_end());
  83 }
  84
  85 struct protocol udp_ops = {
  86         .key = 0x11,
  87         .print_full = udp,
  88         .print_less = udp_less,
  89 };