src/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 uint16_t udp_port(uint16_t src, uint16_t dst)
  25 {
  26         char *tmp1, *tmp2;
  27
  28         src = ntohs(src);
  29         dst = ntohs(dst);
  30
  31         /* XXX: Is there a better way to determine? */
  32         if (src < dst && src < 1024) {
  33                 return src;
  34         } else if (dst < src && dst < 1024) {
  35                 return dst;
  36         } else {
  37                 tmp1 = lookup_port_udp(src);
  38                 tmp2 = lookup_port_udp(dst);
  39                 if (tmp1 && !tmp2) {
  40                         return src;
  41                 } else if (!tmp1 && tmp2) {
  42                         return dst;
  43                 } else {
  44                         if (src < dst)
  45                                 return src;
  46                         else
  47                                 return dst;
  48                 }
  49         }
  50 }
  51
  52 static void udp(struct pkt_buff *pkt)
  53 {
  54         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  55
  56         if (udp == NULL)
  57                 return;
  58
  59         tprintf(" [ UDP ");
  60         tprintf("Port (%u => %u, %s%s%s), ",
  61                 ntohs(udp->source), ntohs(udp->dest),
  62                 colorize_start(bold),
  63                 lookup_port_udp(udp_port(udp->source, udp->dest)),
  64                 colorize_end());
  65         tprintf("Len (%u), ", ntohs(udp->len));
  66         tprintf("CSum (0x%.4x)", ntohs(udp->check));
  67         tprintf(" ]\n");
  68
  69         pkt_set_proto(pkt, &eth_lay4, udp_port(udp->source, udp->dest));
  70 }
  71
  72 static void udp_less(struct pkt_buff *pkt)
  73 {
  74         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  75
  76         if (udp == NULL)
  77                 return;
  78
  79         tprintf(" UDP %s%s%s %u/%u",
  80                 colorize_start(bold),
  81                 lookup_port_udp(udp_port(udp->source, udp->dest)),
  82                 colorize_end(), ntohs(udp->source), ntohs(udp->dest));
  83
  84         pkt_set_proto(pkt, &eth_lay4, udp_port(udp->source, udp->dest));
  85 }
  86
  87 struct protocol udp_ops = {
  88         .key = 0x11,
  89         .print_full = udp,
  90         .print_less = udp_less,
  91 };
  92
  93 EXPORT_SYMBOL(udp_ops);