lib/libalias/alias_cuseeme.c

   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  * $FreeBSD: src/lib/libalias/alias_cuseeme.c,v 1.2.2.2 2000/10/31 08:48:21 ru Exp $
  29  * $DragonFly: src/lib/libalias/alias_cuseeme.c,v 1.3 2004/08/20 01:21:36 joerg Exp $
  30  */
  31
  32 #include <sys/param.h>
  33 #include <netinet/in_systm.h>
  34 #include <netinet/in.h>
  35 #include <netinet/ip.h>
  36 #include <netinet/udp.h>
  37
  38 #include "alias_local.h"
  39
  40 /* CU-SeeMe Data Header */
  41 struct cu_header {
  42     u_int16_t dest_family;
  43     u_int16_t dest_port;
  44     u_int32_t  dest_addr;
  45     int16_t family;
  46     u_int16_t port;
  47     u_int32_t addr;
  48     u_int32_t seq;
  49     u_int16_t msg;
  50     u_int16_t data_type;
  51     u_int16_t packet_len;
  52 };
  53
  54 /* Open Continue Header */
  55 struct oc_header {
  56     u_int16_t client_count;    /* Number of client info structs */
  57     u_int32_t seq_no;
  58     char user_name[20];
  59     char reserved[4];        /* flags, version stuff, etc */
  60 };
  61
  62 /* client info structures */
  63 struct client_info {
  64     u_int32_t address;          /* Client address */
  65     char reserved[8];        /* Flags, pruning bitfield, packet counts etc */
  66 };
  67
  68 void
  69 AliasHandleCUSeeMeOut(struct ip *pip, struct alias_link *link)
  70 {
  71   struct udphdr *ud;
  72
  73   ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
  74   if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
  75     struct cu_header *cu;
  76     struct alias_link *cu_link;
  77
  78     cu = (struct cu_header *)(ud + 1);
  79     if (cu->addr)
  80       cu->addr = (u_int32_t)GetAliasAddress(link).s_addr;
  81
  82     cu_link = FindUdpTcpOut(pip->ip_src, GetDestAddress(link),
  83                             ud->uh_dport, 0, IPPROTO_UDP, 1);
  84
  85 #ifndef NO_FW_PUNCH
  86     if (cu_link)
  87         PunchFWHole(cu_link);
  88 #endif
  89   }
  90 }
  91
  92 void
  93 AliasHandleCUSeeMeIn(struct ip *pip, struct in_addr original_addr)
  94 {
  95   struct in_addr alias_addr;
  96   struct udphdr *ud;
  97   struct cu_header *cu;
  98   struct oc_header *oc;
  99   struct client_info *ci;
 100   char *end;
 101   int i;
 102
 103   alias_addr.s_addr = pip->ip_dst.s_addr;
 104   ud = (struct udphdr *)((char *)pip + (pip->ip_hl << 2));
 105   cu = (struct cu_header *)(ud + 1);
 106   oc = (struct oc_header *)(cu + 1);
 107   ci = (struct client_info *)(oc + 1);
 108   end = (char *)ud + ntohs(ud->uh_ulen);
 109
 110   if ((char *)oc <= end) {
 111     if(cu->dest_addr)
 112       cu->dest_addr = (u_int32_t)original_addr.s_addr;
 113     if(ntohs(cu->data_type) == 101)
 114       /* Find and change our address */
 115       for(i = 0; (char *)(ci + 1) <= end && i < oc->client_count; i++, ci++)
 116         if(ci->address == (u_int32_t)alias_addr.s_addr) {
 117           ci->address = (u_int32_t)original_addr.s_addr;
 118           break;
 119         }
 120   }
 121 }