alias_cuseeme.c revision 131614 
1/*-
2 * Copyright (c) 1998 Brian Somers <brian@Awfulhak.org>
3 *                    with the aid of code written by
4 *                    Junichi SATOH <junichi@astec.co.jp> 1996, 1997.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: head/sys/netinet/libalias/alias_cuseeme.c 131614 2004-07-05 11:10:57Z des $");
31
32#include <stdio.h>
33#include <sys/types.h>
34#include <netinet/in_systm.h>
35#include <netinet/in.h>
36#include <netinet/ip.h>
37#include <netinet/udp.h>
38
39#include "alias_local.h"
40
41/* CU-SeeMe Data Header */
42struct cu_header {
43	u_int16_t	dest_family;
44	u_int16_t	dest_port;
45	u_int32_t	dest_addr;
46	int16_t		family;
47	u_int16_t	port;
48	u_int32_t	addr;
49	u_int32_t	seq;
50	u_int16_t	msg;
51	u_int16_t	data_type;
52	u_int16_t	packet_len;
53};
54
55/* Open Continue Header */
56struct oc_header {
57	u_int16_t	client_count;	/* Number of client info structs */
58	u_int32_t	seq_no;
59	char		user_name [20];
60	char		reserved  [4];	/* flags, version stuff, etc */
61};
62
63/* client info structures */
64struct client_info {
65	u_int32_t	address;/* Client address */
66	char		reserved  [8];	/* Flags, pruning bitfield, packet
67					 * counts etc */
68};
69
70void
71AliasHandleCUSeeMeOut(struct libalias *la, struct ip *pip, struct alias_link *lnk)
72{
73	struct udphdr *ud;
74
75	ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
76	if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
77		struct cu_header *cu;
78		struct alias_link *cu_lnk;
79
80		cu = (struct cu_header *)(ud + 1);
81		if (cu->addr)
82			cu->addr = (u_int32_t) GetAliasAddress(lnk).s_addr;
83
84		cu_lnk = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk),
85		    ud->uh_dport, 0, IPPROTO_UDP, 1);
86
87#ifndef NO_FW_PUNCH
88		if (cu_lnk)
89			PunchFWHole(cu_lnk);
90#endif
91	}
92}
93
94void
95AliasHandleCUSeeMeIn(struct libalias *la, struct ip *pip, struct in_addr original_addr)
96{
97	struct in_addr alias_addr;
98	struct udphdr *ud;
99	struct cu_header *cu;
100	struct oc_header *oc;
101	struct client_info *ci;
102	char *end;
103	int i;
104
105	(void)la;
106	alias_addr.s_addr = pip->ip_dst.s_addr;
107	ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
108	cu = (struct cu_header *)(ud + 1);
109	oc = (struct oc_header *)(cu + 1);
110	ci = (struct client_info *)(oc + 1);
111	end = (char *)ud + ntohs(ud->uh_ulen);
112
113	if ((char *)oc <= end) {
114		if (cu->dest_addr)
115			cu->dest_addr = (u_int32_t) original_addr.s_addr;
116		if (ntohs(cu->data_type) == 101)
117			/* Find and change our address */
118			for (i = 0; (char *)(ci + 1) <= end && i < oc->client_count; i++, ci++)
119				if (ci->address == (u_int32_t) alias_addr.s_addr) {
120					ci->address = (u_int32_t) original_addr.s_addr;
121					break;
122				}
123	}
124}
125