src/proto_udp.h

   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 #ifndef UDP_H
   9 #define UDP_H
  10
  11 #include <stdio.h>
  12 #include <stdint.h>
  13 #include <netinet/in.h>    /* for ntohs() */
  14
  15 #include "proto_struct.h"
  16 #include "dissector_eth.h"
  17 #include "pkt_buff.h"
  18
  19 struct udphdr {
  20         uint16_t source;
  21         uint16_t dest;
  22         uint16_t len;
  23         uint16_t check;
  24 } __attribute__((packed));
  25
  26 static inline uint16_t udp_port(uint16_t src, uint16_t dst)
  27 {
  28         char *tmp1, *tmp2;
  29
  30         src = ntohs(src);
  31         dst = ntohs(dst);
  32
  33         /* XXX: Is there a better way to determine? */
  34         if (src < dst && src < 1024) {
  35                 return src;
  36         } else if (dst < src && dst < 1024) {
  37                 return dst;
  38         } else {
  39                 tmp1 = lookup_port_udp(src);
  40                 tmp2 = lookup_port_udp(dst);
  41                 if (tmp1 && !tmp2) {
  42                         return src;
  43                 } else if (!tmp1 && tmp2) {
  44                         return dst;
  45                 } else {
  46                         if (src < dst)
  47                                 return src;
  48                         else
  49                                 return dst;
  50                 }
  51         }
  52 }
  53
  54 static inline void udp(struct pkt_buff *pkt)
  55 {
  56         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  57
  58         if (udp == NULL)
  59                 return;
  60
  61         tprintf(" [ UDP ");
  62         tprintf("Port (%u => %u, %s%s%s), ",
  63                 ntohs(udp->source), ntohs(udp->dest),
  64                 colorize_start(bold),
  65                 lookup_port_udp(udp_port(udp->source, udp->dest)),
  66                 colorize_end());
  67         tprintf("Len (%u), ", ntohs(udp->len));
  68         tprintf("CSum (0x%.4x)", ntohs(udp->check));
  69         tprintf(" ]\n");
  70
  71         pkt_set_proto(pkt, &eth_lay4, udp_port(udp->source, udp->dest));
  72 }
  73
  74 static inline void udp_less(struct pkt_buff *pkt)
  75 {
  76         struct udphdr *udp = (struct udphdr *) pkt_pull(pkt, sizeof(*udp));
  77
  78         if (udp == NULL)
  79                 return;
  80
  81         tprintf(" UDP %s%s%s %u/%u",
  82                 colorize_start(bold),
  83                 lookup_port_udp(udp_port(udp->source, udp->dest)),
  84                 colorize_end(), ntohs(udp->source), ntohs(udp->dest));
  85
  86         pkt_set_proto(pkt, &eth_lay4, udp_port(udp->source, udp->dest));
  87 }
  88
  89 struct protocol udp_ops = {
  90         .key = 0x11,
  91         .print_full = udp,
  92         .print_less = udp_less,
  93 };
  94
  95 #endif /* UDP_H */