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
  18 struct udphdr {
  19         uint16_t source;
  20         uint16_t dest;
  21         uint16_t len;
  22         uint16_t check;
  23 } __attribute__((packed));
  24
  25 static inline uint16_t udp_port(uint16_t src, uint16_t dst)
  26 {
  27         char *tmp1, *tmp2;
  28
  29         src = ntohs(src);
  30         dst = ntohs(dst);
  31
  32         /* XXX: Is there a better way to determine? */
  33         if (src < dst && src < 1024) {
  34                 return src;
  35         } else if (dst < src && dst < 1024) {
  36                 return dst;
  37         } else {
  38                 tmp1 = lookup_port_udp(src);
  39                 tmp2 = lookup_port_udp(dst);
  40                 if (tmp1 && !tmp2) {
  41                         return src;
  42                 } else if (!tmp1 && tmp2) {
  43                         return dst;
  44                 } else {
  45                         if (src < dst)
  46                                 return src;
  47                         else
  48                                 return dst;
  49                 }
  50         }
  51 }
  52
  53 static inline void udp(uint8_t *packet, size_t len)
  54 {
  55         struct udphdr *udp = (struct udphdr *) packet;
  56
  57         if (len < sizeof(struct udphdr))
  58                 return;
  59
  60         tprintf(" [ UDP ");
  61         tprintf("Port (%u => %u, %s%s%s), ",
  62                 ntohs(udp->source), ntohs(udp->dest),
  63                 colorize_start(bold),
  64                 lookup_port_udp(udp_port(udp->source, udp->dest)),
  65                 colorize_end());
  66         tprintf("Len (%u), ", ntohs(udp->len));
  67         tprintf("CSum (0x%.4x)", ntohs(udp->check));
  68         tprintf(" ]\n");
  69 }
  70
  71 static inline void udp_less(uint8_t *packet, size_t len)
  72 {
  73         struct udphdr *udp = (struct udphdr *) packet;
  74
  75         if (len < sizeof(struct udphdr))
  76                 return;
  77
  78         tprintf(" UDP %s%s%s %u/%u",
  79                 colorize_start(bold),
  80                 lookup_port_udp(udp_port(udp->source, udp->dest)),
  81                 colorize_end(), ntohs(udp->source), ntohs(udp->dest));
  82 }
  83
  84 static inline void udp_next(uint8_t *packet, size_t len,
  85                             struct hash_table **table,
  86                             unsigned int *key, size_t *off)
  87 {
  88         struct udphdr *udp = (struct udphdr *) packet;
  89
  90         if (len < sizeof(struct udphdr))
  91                 goto invalid;
  92
  93         (*off) = sizeof(struct udphdr);
  94         (*key) = udp_port(udp->source, udp->dest);
  95         (*table) = &eth_lay4;
  96
  97         return;
  98 invalid:
  99         (*off) = 0;
 100         (*key) = 0;
 101         (*table) = NULL;
 102 }
 103
 104 struct protocol udp_ops = {
 105         .key = 0x11,
 106         .offset = sizeof(struct udphdr),
 107         .print_full = udp,
 108         .print_less = udp_less,
 109         .print_pay_ascii = empty,
 110         .print_pay_hex = empty,
 111         .print_pay_none = udp,
 112         .print_all_cstyle = __hex2,
 113         .print_all_hex = __hex,
 114         .proto_next = udp_next,
 115 };
 116
 117 #endif /* UDP_H */