alias_cuseeme.c revision 124621 
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 124621 2004-01-17 10:52:21Z phk $");
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 counts etc */
67};
68
69void
70AliasHandleCUSeeMeOut(struct libalias *la, struct ip *pip, struct alias_link *link)
71{
72  struct udphdr *ud;
73
74  ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
75  if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
76    struct cu_header *cu;
77    struct alias_link *cu_link;
78
79    cu = (struct cu_header *)(ud + 1);
80    if (cu->addr)
81      cu->addr = (u_int32_t)GetAliasAddress(link).s_addr;
82
83    cu_link = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(link),
84                            ud->uh_dport, 0, IPPROTO_UDP, 1);
85
86#ifndef NO_FW_PUNCH
87    if (cu_link)
88        PunchFWHole(cu_link);
89#endif
90  }
91}
92
93void
94AliasHandleCUSeeMeIn(struct libalias *la, struct ip *pip, struct in_addr original_addr)
95{
96  struct in_addr alias_addr;
97  struct udphdr *ud;
98  struct cu_header *cu;
99  struct oc_header *oc;
100  struct client_info *ci;
101  char *end;
102  int i;
103
104  alias_addr.s_addr = pip->ip_dst.s_addr;
105  ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
106  cu = (struct cu_header *)(ud + 1);
107  oc = (struct oc_header *)(cu + 1);
108  ci = (struct client_info *)(oc + 1);
109  end = (char *)ud + ntohs(ud->uh_ulen);
110
111  if ((char *)oc <= end) {
112    if(cu->dest_addr)
113      cu->dest_addr = (u_int32_t)original_addr.s_addr;
114    if(ntohs(cu->data_type) == 101)
115      /* Find and change our address */
116      for(i = 0; (char *)(ci + 1) <= end && i < oc->client_count; i++, ci++)
117        if(ci->address == (u_int32_t)alias_addr.s_addr) {
118          ci->address = (u_int32_t)original_addr.s_addr;
119          break;
120        }
121  }
122}
123