alias/alias_cuseeme.c

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*-
  23  * Copyright (c) 1998 Brian Somers <brian@Awfulhak.org>
  24  *                    with the aid of code written by
  25  *                    Junichi SATOH <junichi@astec.co.jp> 1996, 1997.
  26  * All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  *
  37  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  38  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  39  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  40  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  41  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  42  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  43  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  45  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  46  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  47  * SUCH DAMAGE.
  48  *
  49  * Based upon:
  50  * $FreeBSD: src/lib/libalias/alias_cuseeme.c,v 1.2.2.2 2000/10/31 08:48:21 ru Exp $
  51  */
  52
  53 #include <sys/types.h>
  54 #include <netinet/in_systm.h>
  55 #include <netinet/in.h>
  56 #include <netinet/ip.h>
  57 #include <netinet/udp.h>
  58
  59 #include "alias_local.h"
  60
  61 /* CU-SeeMe Data Header */
  62 struct cu_header {
  63     u_int16_t dest_family;
  64     u_int16_t dest_port;
  65     u_int32_t  dest_addr;
  66     int16_t family;
  67     u_int16_t port;
  68     u_int32_t addr;
  69     u_int32_t seq;
  70     u_int16_t msg;
  71     u_int16_t data_type;
  72     u_int16_t packet_len;
  73 };
  74
  75 /* Open Continue Header */
  76 struct oc_header {
  77     u_int16_t client_count;    /* Number of client info structs */
  78     u_int32_t seq_no;
  79     char user_name[20];
  80     char reserved[4];        /* flags, version stuff, etc */
  81 };
  82
  83 /* client info structures */
  84 struct client_info {
  85     u_int32_t address;          /* Client address */
  86     char reserved[8];        /* Flags, pruning bitfield, packet counts etc */
  87 };
  88
  89 void
  90 AliasHandleCUSeeMeOut(struct ip *pip, struct alias_link *link)
  91 {
  92   struct udphdr *ud;
  93
  94   ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
  95   if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
  96     struct cu_header *cu;
  97     struct alias_link *cu_link;
  98
  99     cu = (struct cu_header *)(ud + 1);
 100     if (cu->addr)
 101       cu->addr = (u_int32_t)GetAliasAddress(link).s_addr;
 102
 103     cu_link = FindUdpTcpOut(pip->ip_src, GetDestAddress(link),
 104                             ud->uh_dport, 0, IPPROTO_UDP, 1);
 105
 106 #ifndef NO_FW_PUNCH
 107     if (cu_link)
 108         PunchFWHole(cu_link);
 109 #endif
 110   }
 111 }
 112
 113 void
 114 AliasHandleCUSeeMeIn(struct ip *pip, struct in_addr original_addr)
 115 {
 116   struct in_addr alias_addr;
 117   struct udphdr *ud;
 118   struct cu_header *cu;
 119   struct oc_header *oc;
 120   struct client_info *ci;
 121   char *end;
 122   int i;
 123
 124   alias_addr.s_addr = pip->ip_dst.s_addr;
 125   ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
 126   cu = (struct cu_header *)(ud + 1);
 127   oc = (struct oc_header *)(cu + 1);
 128   ci = (struct client_info *)(oc + 1);
 129   end = (char *)ud + ntohs(ud->uh_ulen);
 130
 131   if ((char *)oc <= end) {
 132     if(cu->dest_addr)
 133       cu->dest_addr = (u_int32_t)original_addr.s_addr;
 134     if(ntohs(cu->data_type) == 101)
 135       /* Find and change our address */
 136       for(i = 0; (char *)(ci + 1) <= end && i < oc->client_count; i++, ci++)
 137         if(ci->address == (u_int32_t)alias_addr.s_addr) {
 138           ci->address = (u_int32_t)original_addr.s_addr;
 139           break;
 140         }
 141   }
 142 }