forked from osmocom/wireshark
258 lines
6.9 KiB
C
258 lines
6.9 KiB
C
/* packet-udp.c
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* Routines for UDP packet disassembly
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*
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* $Id: packet-udp.c,v 1.14 1999/03/23 03:14:45 gram Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@zing.org>
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* Copyright 1998 Gerald Combs
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*
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* Richard Sharpe, 13-Feb-1999, added dispatch table support and
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* support for tftp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#ifdef HAVE_SYS_TYPES_H
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# include <sys/types.h>
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#endif
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#ifdef HAVE_NETINET_IN_H
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# include <netinet/in.h>
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <glib.h>
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#include "packet.h"
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#include "resolv.h"
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/* UDP structs and definitions */
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typedef struct _e_udphdr {
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guint16 uh_sport;
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guint16 uh_dport;
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guint16 uh_ulen;
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guint16 uh_sum;
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} e_udphdr;
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/* UDP Ports -> should go in packet-udp.h */
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#define UDP_PORT_DNS 53
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#define UDP_PORT_BOOTPS 67
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#define UDP_PORT_TFTP 69
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#define UDP_PORT_IPX 213
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#define UDP_PORT_NBNS 137
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#define UDP_PORT_NBDGM 138
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#define UDP_PORT_RIP 520
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#define UDP_PORT_VINES 573
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struct hash_struct {
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guint16 proto;
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void (*dissect)(const u_char *, int, frame_data *, proto_tree *);
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struct hash_struct *next;
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};
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struct hash_struct *hash_table[256];
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/*
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* These routines are for UDP, will be generalized soon: RJS
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*
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* XXX - note that they should probably check the IP address as well as
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* the port number, so that we don't mistakenly identify packets as, say,
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* TFTP, merely because they have a source or destination port number
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* equal to the port being used by a TFTP daemon on some machine other
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* than the one they're going to or from.
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*/
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struct hash_struct *udp_find_hash_ent(guint16 proto) {
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int idx = proto % 256;
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struct hash_struct *hash_ent = hash_table[idx];
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while (hash_ent != NULL) {
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if (hash_ent -> proto == proto)
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return hash_ent;
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hash_ent = hash_ent -> next;
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}
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return NULL;
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}
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void udp_hash_add(guint16 proto,
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void (*dissect)(const u_char *, int, frame_data *, proto_tree *)) {
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int idx = proto % 256; /* Simply take the remainder, hope for no collisions */
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struct hash_struct *hash_ent = (struct hash_struct *)malloc(sizeof(struct hash_struct));
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struct hash_struct *hash_ent2;
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hash_ent -> proto = proto;
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hash_ent -> dissect = dissect;
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hash_ent -> next = NULL;
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if (hash_ent == NULL) {
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fprintf(stderr, "Could not allocate space for hash structure in dissect_udp\n");
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exit(1);
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}
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if (hash_table[idx]) { /* Something, add on end */
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hash_ent2 = hash_table[idx];
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while (hash_ent2 -> next != NULL)
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hash_ent2 = hash_ent2 -> next;
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hash_ent2 -> next = hash_ent; /* Bad in pathalogical cases */
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}
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else {
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hash_table[idx] = hash_ent;
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}
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}
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void init_dissect_udp(void) {
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int i;
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for (i = 0; i < 256; i++) {
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hash_table[i] = NULL;
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}
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/* Now add the protocols we know about */
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udp_hash_add(UDP_PORT_BOOTPS, dissect_bootp);
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udp_hash_add(UDP_PORT_TFTP, dissect_tftp);
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}
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void
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dissect_udp(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
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e_udphdr uh;
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guint16 uh_sport, uh_dport, uh_ulen, uh_sum;
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struct hash_struct *dissect_routine = NULL;
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proto_tree *udp_tree;
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proto_item *ti;
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/* To do: Check for {cap len,pkt len} < struct len */
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/* Avoids alignment problems on many architectures. */
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memcpy(&uh, &pd[offset], sizeof(e_udphdr));
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uh_sport = ntohs(uh.uh_sport);
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uh_dport = ntohs(uh.uh_dport);
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uh_ulen = ntohs(uh.uh_ulen);
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uh_sum = ntohs(uh.uh_sum);
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if (check_col(fd, COL_PROTOCOL))
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col_add_str(fd, COL_PROTOCOL, "UDP");
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if (check_col(fd, COL_INFO))
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col_add_fstr(fd, COL_INFO, "Source port: %s Destination port: %s",
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get_udp_port(uh_sport), get_udp_port(uh_dport));
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if (check_col(fd, COL_RES_SRC_PORT))
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col_add_str(fd, COL_RES_SRC_PORT, get_udp_port(uh_sport));
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if (check_col(fd, COL_UNRES_SRC_PORT))
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col_add_fstr(fd, COL_UNRES_SRC_PORT, "%u", uh_sport);
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if (check_col(fd, COL_RES_DST_PORT))
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col_add_str(fd, COL_RES_DST_PORT, get_udp_port(uh_dport));
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if (check_col(fd, COL_UNRES_DST_PORT))
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col_add_fstr(fd, COL_UNRES_DST_PORT, "%u", uh_dport);
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if (tree) {
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ti = proto_tree_add_item(tree, offset, 8, "User Datagram Protocol");
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udp_tree = proto_tree_new();
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proto_item_add_subtree(ti, udp_tree, ETT_UDP);
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proto_tree_add_item(udp_tree, offset, 2, "Source port: %s (%u)",
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get_udp_port(uh_sport), uh_sport);
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proto_tree_add_item(udp_tree, offset + 2, 2, "Destination port: %s (%u)",
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get_udp_port(uh_dport), uh_dport);
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proto_tree_add_item(udp_tree, offset + 4, 2, "Length: %u", uh_ulen);
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proto_tree_add_item(udp_tree, offset + 6, 2, "Checksum: 0x%04x", uh_sum);
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}
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/* Skip over header */
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offset += 8;
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/* To do: make sure we aren't screwing ourselves with the MIN call. */
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switch (MIN(uh_sport, uh_dport)) {
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case UDP_PORT_BOOTPS:
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dissect_bootp(pd, offset, fd, tree);
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break;
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case UDP_PORT_DNS:
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dissect_dns(pd, offset, fd, tree);
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break;
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case UDP_PORT_RIP:
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/* we should check the source port too (RIP: UDP src and dst port 520) */
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dissect_rip(pd, offset, fd, tree);
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break;
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case UDP_PORT_NBNS:
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dissect_nbns(pd, offset, fd, tree);
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break;
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case UDP_PORT_NBDGM:
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dissect_nbdgm(pd, offset, fd, tree);
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break;
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case UDP_PORT_IPX: /* RFC 1234 */
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dissect_ipx(pd, offset, fd, tree);
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break;
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case UDP_PORT_VINES:
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/* FIXME: AFAIK, src and dst port must be the same */
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dissect_vines_frp(pd, offset, fd, tree);
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break;
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case UDP_PORT_TFTP:
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/* This is the first point of call, but it adds a dynamic call */
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udp_hash_add(MAX(uh_sport, uh_dport), dissect_tftp); /* Add to table */
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dissect_tftp(pd, offset, fd, tree);
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break;
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default:
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/* OK, find a routine in the table, else use the default */
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if ((dissect_routine = udp_find_hash_ent(uh_sport))) {
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struct hash_struct *dr2 = udp_find_hash_ent(uh_dport);
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if (dr2 == NULL) { /* Not in the table, add */
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udp_hash_add(uh_dport, dissect_tftp);
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}
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dissect_routine -> dissect(pd, offset, fd, tree);
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}
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else if ((dissect_routine = udp_find_hash_ent(uh_dport))) {
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dissect_routine -> dissect(pd, offset, fd, tree);
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}
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else {
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dissect_data(pd, offset, fd, tree);
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}
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}
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}
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