alias/alias.h

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 2001 Charles Mott <cmott@scientech.com>
  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.h,v 1.12.2.4 2001/08/01 09:36:40 obrien Exp $
  52  */
  53
  54 /*-
  55  * Alias.h defines the outside world interfaces for the packet aliasing
  56  * software.
  57  *
  58  * This software is placed into the public domain with no restrictions on its
  59  * distribution.
  60  */
  61
  62 #ifndef _ALIAS_H_
  63 #define _ALIAS_H_
  64
  65 /* Alias link representative (incomplete struct) */
  66 struct alias_link;
  67
  68 /* External interfaces (API) to packet aliasing engine */
  69
  70 /* Initialization and Control */
  71     extern void
  72     PacketAliasInit(void);
  73
  74     extern void
  75     PacketAliasUninit(void);
  76
  77     extern void
  78     PacketAliasSetAddress(struct in_addr);
  79
  80     extern unsigned int
  81     PacketAliasSetMode(unsigned int, unsigned int);
  82
  83 #ifndef NO_FW_PUNCH
  84     extern void
  85     PacketAliasSetFWBase(unsigned int, unsigned int);
  86 #endif
  87
  88     extern void
  89     PacketAliasClampMSS(u_short mss);
  90
  91 /* Packet Handling */
  92     extern int
  93     PacketAliasIn(char *, int maxpacketsize);
  94
  95     extern int
  96     PacketAliasOut(char *, int maxpacketsize);
  97
  98     extern int
  99     PacketUnaliasOut(char *, int maxpacketsize);
 100
 101 /* Port and Address Redirection */
 102     extern struct alias_link *
 103     PacketAliasRedirectPort(struct in_addr, u_short,
 104                             struct in_addr, u_short,
 105                             struct in_addr, u_short,
 106                             u_char);
 107
 108     extern int
 109     PacketAliasAddServer(struct alias_link *link,
 110                          struct in_addr addr,
 111                          u_short port);
 112
 113     extern struct alias_link *
 114     PacketAliasRedirectProto(struct in_addr,
 115                              struct in_addr,
 116                              struct in_addr,
 117                              u_char);
 118
 119     extern struct alias_link *
 120     PacketAliasRedirectAddr(struct in_addr,
 121                             struct in_addr);
 122
 123     extern void
 124     PacketAliasRedirectDelete(struct alias_link *);
 125
 126 /* Fragment Handling */
 127     extern int
 128     PacketAliasSaveFragment(char *);
 129
 130     extern char *
 131     PacketAliasGetFragment(char *);
 132
 133     extern void
 134     PacketAliasFragmentIn(char *, char *);
 135
 136 /* Miscellaneous Functions */
 137     extern void
 138     PacketAliasSetTarget(struct in_addr addr);
 139
 140     extern int
 141     PacketAliasCheckNewLink(void);
 142
 143     extern u_short
 144     PacketAliasInternetChecksum(u_short *, int);
 145
 146 /* Transparent Proxying */
 147     extern int
 148     PacketAliasProxyRule(const char *);
 149
 150
 151 /********************** Mode flags ********************/
 152 /* Set these flags using PacketAliasSetMode() */
 153
 154 /* If PKT_ALIAS_LOG is set, a message will be printed to
 155         /var/log/alias.log every time a link is created or deleted.  This
 156         is useful for debugging */
 157 #define PKT_ALIAS_LOG 0x01
 158
 159 /* If PKT_ALIAS_DENY_INCOMING is set, then incoming connections (e.g.
 160         to ftp, telnet or web servers will be prevented by the aliasing
 161         mechanism.  */
 162 #define PKT_ALIAS_DENY_INCOMING 0x02
 163
 164 /* If PKT_ALIAS_SAME_PORTS is set, packets will be attempted sent from
 165         the same port as they originated on.  This allows e.g. rsh to work
 166         *99% of the time*, but _not_ 100%.  (It will be slightly flakey
 167         instead of not working at all.)  This mode bit is set by
 168         PacketAliasInit(), so it is a default mode of operation. */
 169 #define PKT_ALIAS_SAME_PORTS 0x04
 170
 171 /* If PKT_ALIAS_USE_SOCKETS is set, then when partially specified
 172         links (e.g. destination port and/or address is zero), the packet
 173         aliasing engine will attempt to allocate a socket for the aliasing
 174         port it chooses.  This will avoid interference with the host
 175         machine.  Fully specified links do not require this.  This bit
 176         is set after a call to PacketAliasInit(), so it is a default
 177         mode of operation. */
 178 #define PKT_ALIAS_USE_SOCKETS 0x08
 179
 180 /* If PKT_ALIAS_UNREGISTERED_ONLY is set, then only packets with
 181         unregistered source addresses will be aliased.  Private
 182         addresses are those in the following ranges:
 183                 10.0.0.0     ->   10.255.255.255
 184                 172.16.0.0   ->   172.31.255.255
 185                 192.168.0.0  ->   192.168.255.255  */
 186 #define PKT_ALIAS_UNREGISTERED_ONLY 0x10
 187
 188 /* If PKT_ALIAS_RESET_ON_ADDR_CHANGE is set, then the table of dynamic
 189         aliasing links will be reset whenever PacketAliasSetAddress()
 190         changes the default aliasing address.  If the default aliasing
 191         address is left unchanged by this function call, then the
 192         table of dynamic aliasing links will be left intact.  This
 193         bit is set after a call to PacketAliasInit(). */
 194 #define PKT_ALIAS_RESET_ON_ADDR_CHANGE 0x20
 195
 196 #ifndef NO_FW_PUNCH
 197 /* If PKT_ALIAS_PUNCH_FW is set, active FTP and IRC DCC connections
 198    will create a 'hole' in the firewall to allow the transfers to
 199    work.  Where (IPFW "line-numbers") the hole is created is
 200    controlled by PacketAliasSetFWBase(base, size). The hole will be
 201    attached to that particular alias_link, so when the link goes away
 202    so do the hole.  */
 203 #define PKT_ALIAS_PUNCH_FW 0x100
 204 #endif
 205
 206 /* If PKT_ALIAS_PROXY_ONLY is set, then NAT will be disabled and only
 207       transparent proxying performed */
 208 #define PKT_ALIAS_PROXY_ONLY 0x40
 209
 210 /* If PKT_ALIAS_REVERSE is set, the actions of PacketAliasIn()
 211       and PacketAliasOut() are reversed */
 212 #define PKT_ALIAS_REVERSE 0x80
 213
 214 /* Return Codes */
 215 #define PKT_ALIAS_ERROR -1
 216 #define PKT_ALIAS_OK 1
 217 #define PKT_ALIAS_IGNORED 2
 218 #define PKT_ALIAS_UNRESOLVED_FRAGMENT 3
 219 #define PKT_ALIAS_FOUND_HEADER_FRAGMENT 4
 220
 221 #endif
 222 /* lint -restore */