proto_udp.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2009, 2010 Daniel Borkmann.
   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 "protos.h"
  14 #include "dissector_eth.h"
  15 #include "pkt_buff.h"
  16
  17 struct udphdr {
  18         uint16_t source;
  19         uint16_t dest;
  20         uint16_t len;
  21         uint16_t check;
  22 } __attribute__((packed));
  23
  24 static void udp(struct pkt_buff *pkt)
  25 {
  26         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  27         ssize_t len;
  28         uint16_t src, dest;
  29         char *src_name, *dest_name;
  30
  31         if (udp == NULL)
  32                 return;
  33
  34         len = ntohs(udp->len) - sizeof(*udp);
  35         src = ntohs(udp->source);
  36         dest = ntohs(udp->dest);
  37
  38         src_name = lookup_port_udp(src);
  39         dest_name = lookup_port_udp(dest);
  40
  41         tprintf(" [ UDP ");
  42         tprintf("Port (%u", src);
  43         if (src_name)
  44                 tprintf(" (%s%s%s)", colorize_start(bold), src_name,
  45                         colorize_end());
  46         tprintf(" => %u", dest);
  47         if (dest_name)
  48                 tprintf(" (%s%s%s)", colorize_start(bold), dest_name,
  49                         colorize_end());
  50         tprintf("), ");
  51         if(len > pkt_len(pkt) || len < 0){
  52                 tprintf("Len (%u) %s, ", ntohs(udp->len),
  53                         colorize_start_full(black, red)
  54                         "invalid" colorize_end());
  55         }
  56         tprintf("Len (%u Bytes, %zd Bytes Data), ", ntohs(udp->len), len);
  57         tprintf("CSum (0x%.4x)", ntohs(udp->check));
  58         tprintf(" ]\n");
  59 }
  60
  61 static void udp_less(struct pkt_buff *pkt)
  62 {
  63         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  64         uint16_t src, dest;
  65         char *src_name, *dest_name;
  66
  67         if (udp == NULL)
  68                 return;
  69
  70         src = ntohs(udp->source);
  71         dest = ntohs(udp->dest);
  72
  73         src_name = lookup_port_udp(src);
  74         dest_name = lookup_port_udp(dest);
  75
  76         tprintf(" UDP %u", src);
  77         if(src_name)
  78                 tprintf("(%s%s%s)", colorize_start(bold), src_name,
  79                         colorize_end());
  80         tprintf("/%u", dest);
  81         if (dest_name)
  82                 tprintf("(%s%s%s)", colorize_start(bold), dest_name,
  83                         colorize_end());
  84 }
  85
  86 struct protocol udp_ops = {
  87         .key = 0x11,
  88         .print_full = udp,
  89         .print_less = udp_less,
  90 };