alias/alias_cuseeme.c

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*-
  24  * Copyright (c) 1998 Brian Somers <brian@Awfulhak.org>
  25  *                    with the aid of code written by
  26  *                    Junichi SATOH <junichi@astec.co.jp> 1996, 1997.
  27  * All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  *
  38  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  39  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  40  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  41  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  42  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  43  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  44  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  45  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  46  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  47  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  48  * SUCH DAMAGE.
  49  *
  50  * Based upon:
  51  * $FreeBSD: src/lib/libalias/alias_cuseeme.c,v 1.2.2.2 2000/10/31 08:48:21 ru Exp $
  52  */
  53
  54 #include <sys/types.h>
  55 #include <netinet/in_systm.h>
  56 #include <netinet/in.h>
  57 #include <netinet/ip.h>
  58 #include <netinet/udp.h>
  59
  60 #include "alias_local.h"
  61
  62 /* CU-SeeMe Data Header */
  63 struct cu_header {
  64     u_int16_t dest_family;
  65     u_int16_t dest_port;
  66     u_int32_t  dest_addr;
  67     int16_t family;
  68     u_int16_t port;
  69     u_int32_t addr;
  70     u_int32_t seq;
  71     u_int16_t msg;
  72     u_int16_t data_type;
  73     u_int16_t packet_len;
  74 };
  75
  76 /* Open Continue Header */
  77 struct oc_header {
  78     u_int16_t client_count;    /* Number of client info structs */
  79     u_int32_t seq_no;
  80     char user_name[20];
  81     char reserved[4];        /* flags, version stuff, etc */
  82 };
  83
  84 /* client info structures */
  85 struct client_info {
  86     u_int32_t address;          /* Client address */
  87     char reserved[8];        /* Flags, pruning bitfield, packet counts etc */
  88 };
  89
  90 void
  91 AliasHandleCUSeeMeOut(struct ip *pip, struct alias_link *link)
  92 {
  93   struct udphdr *ud;
  94
  95   ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
  96   if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
  97     struct cu_header *cu;
  98     struct alias_link *cu_link;
  99
 100     cu = (struct cu_header *)(ud + 1);
 101     if (cu->addr)
 102       cu->addr = (u_int32_t)GetAliasAddress(link).s_addr;
 103
 104     cu_link = FindUdpTcpOut(pip->ip_src, GetDestAddress(link),
 105                             ud->uh_dport, 0, IPPROTO_UDP, 1);
 106
 107 #ifndef NO_FW_PUNCH
 108     if (cu_link)
 109         PunchFWHole(cu_link);
 110 #endif
 111   }
 112 }
 113
 114 void
 115 AliasHandleCUSeeMeIn(struct ip *pip, struct in_addr original_addr)
 116 {
 117   struct in_addr alias_addr;
 118   struct udphdr *ud;
 119   struct cu_header *cu;
 120   struct oc_header *oc;
 121   struct client_info *ci;
 122   char *end;
 123   int i;
 124
 125   alias_addr.s_addr = pip->ip_dst.s_addr;
 126   ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
 127   cu = (struct cu_header *)(ud + 1);
 128   oc = (struct oc_header *)(cu + 1);
 129   ci = (struct client_info *)(oc + 1);
 130   end = (char *)ud + ntohs(ud->uh_ulen);
 131
 132   if ((char *)oc <= end) {
 133     if(cu->dest_addr)
 134       cu->dest_addr = (u_int32_t)original_addr.s_addr;
 135     if(ntohs(cu->data_type) == 101)
 136       /* Find and change our address */
 137       for(i = 0; (char *)(ci + 1) <= end && i < oc->client_count; i++, ci++)
 138         if(ci->address == (u_int32_t)alias_addr.s_addr) {
 139           ci->address = (u_int32_t)original_addr.s_addr;
 140           break;
 141         }
 142   }
 143 }