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