alias.h revision 131614 
1/* lint -save -library Flexelint comment for external headers */
2
3/*-
4 * Copyright (c) 2001 Charles Mott <cm@linktel.net>
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: head/sys/netinet/libalias/alias.h 131614 2004-07-05 11:10:57Z des $
29 */
30
31/*-
32 * Alias.h defines the outside world interfaces for the packet aliasing
33 * software.
34 *
35 * This software is placed into the public domain with no restrictions on its
36 * distribution.
37 */
38
39#ifndef _ALIAS_H_
40#define	_ALIAS_H_
41
42/*
43 * The external interface to libalias, the packet aliasing engine.
44 *
45 * There are two sets of functions:
46 *
47 * PacketAlias*() the old API which doesn't take an instance pointer
48 * and therefore can only have one packet engine at a time.
49 *
50 * LibAlias*() the new API which takes as first argument a pointer to
51 * the instance of the packet aliasing engine.
52 *
53 * The functions otherwise correspond to each other one for one, except
54 * for the LibAliasUnaliasOut()/PacketUnaliasOut() function which were
55 * were misnamed in the old API.
56 */
57
58/*
59 * The instance structure
60 */
61struct libalias;
62
63/*
64 * An anonymous structure, a pointer to which is returned from
65 * PacketAliasRedirectAddr(), PacketAliasRedirectPort() or
66 * PacketAliasRedirectProto(), passed to PacketAliasAddServer(),
67 * and freed by PacketAliasRedirectDelete().
68 */
69struct alias_link;
70
71
72/* OLD API */
73
74/* Initialization and control functions. */
75void		PacketAliasInit(void);
76void		PacketAliasSetAddress(struct in_addr _addr);
77void		PacketAliasSetFWBase(unsigned int _base, unsigned int _num);
78void		PacketAliasSetSkinnyPort(unsigned int _port);
79unsigned int
80		PacketAliasSetMode(unsigned int _flags, unsigned int _mask);
81void		PacketAliasUninit(void);
82
83/* Packet Handling functions. */
84int		PacketAliasIn(char *_ptr, int _maxpacketsize);
85int		PacketAliasOut(char *_ptr, int _maxpacketsize);
86int		PacketUnaliasOut(char *_ptr, int _maxpacketsize);
87
88/* Port and address redirection functions. */
89
90
91int
92PacketAliasAddServer(struct alias_link *_lnk,
93    struct in_addr _addr, unsigned short _port);
94struct alias_link *
95PacketAliasRedirectAddr(struct in_addr _src_addr,
96    struct in_addr _alias_addr);
97int		PacketAliasRedirectDynamic(struct alias_link *_lnk);
98void		PacketAliasRedirectDelete(struct alias_link *_lnk);
99struct alias_link *
100PacketAliasRedirectPort(struct in_addr _src_addr,
101    unsigned short _src_port, struct in_addr _dst_addr,
102    unsigned short _dst_port, struct in_addr _alias_addr,
103    unsigned short _alias_port, unsigned char _proto);
104struct alias_link *
105PacketAliasRedirectProto(struct in_addr _src_addr,
106    struct in_addr _dst_addr, struct in_addr _alias_addr,
107    unsigned char _proto);
108
109/* Fragment Handling functions. */
110void		PacketAliasFragmentIn(char *_ptr, char *_ptr_fragment);
111char           *PacketAliasGetFragment(char *_ptr);
112int		PacketAliasSaveFragment(char *_ptr);
113
114/* Miscellaneous functions. */
115int		PacketAliasCheckNewLink(void);
116unsigned short
117		PacketAliasInternetChecksum(unsigned short *_ptr, int _nbytes);
118void		PacketAliasSetTarget(struct in_addr _target_addr);
119
120/* Transparent proxying routines. */
121int		PacketAliasProxyRule(const char *_cmd);
122
123/* NEW API */
124
125/* Initialization and control functions. */
126struct libalias *LibAliasInit(struct libalias *);
127void		LibAliasSetAddress(struct libalias *, struct in_addr _addr);
128void		LibAliasSetFWBase(struct libalias *, unsigned int _base, unsigned int _num);
129void		LibAliasSetSkinnyPort(struct libalias *, unsigned int _port);
130unsigned int
131		LibAliasSetMode(struct libalias *, unsigned int _flags, unsigned int _mask);
132void		LibAliasUninit(struct libalias *);
133
134/* Packet Handling functions. */
135int		LibAliasIn (struct libalias *, char *_ptr, int _maxpacketsize);
136int		LibAliasOut(struct libalias *, char *_ptr, int _maxpacketsize);
137int		LibAliasOutTry(struct libalias *, char *_ptr, int _maxpacketsize, int _create);
138int		LibAliasUnaliasOut(struct libalias *, char *_ptr, int _maxpacketsize);
139
140/* Port and address redirection functions. */
141
142int
143LibAliasAddServer(struct libalias *, struct alias_link *_lnk,
144    struct in_addr _addr, unsigned short _port);
145struct alias_link *
146LibAliasRedirectAddr(struct libalias *, struct in_addr _src_addr,
147    struct in_addr _alias_addr);
148int		LibAliasRedirectDynamic(struct libalias *, struct alias_link *_lnk);
149void		LibAliasRedirectDelete(struct libalias *, struct alias_link *_lnk);
150struct alias_link *
151LibAliasRedirectPort(struct libalias *, struct in_addr _src_addr,
152    unsigned short _src_port, struct in_addr _dst_addr,
153    unsigned short _dst_port, struct in_addr _alias_addr,
154    unsigned short _alias_port, unsigned char _proto);
155struct alias_link *
156LibAliasRedirectProto(struct libalias *, struct in_addr _src_addr,
157    struct in_addr _dst_addr, struct in_addr _alias_addr,
158    unsigned char _proto);
159
160/* Fragment Handling functions. */
161void		LibAliasFragmentIn(struct libalias *, char *_ptr, char *_ptr_fragment);
162char           *LibAliasGetFragment(struct libalias *, char *_ptr);
163int		LibAliasSaveFragment(struct libalias *, char *_ptr);
164
165/* Miscellaneous functions. */
166int		LibAliasCheckNewLink(struct libalias *);
167unsigned short
168		LibAliasInternetChecksum(struct libalias *, unsigned short *_ptr, int _nbytes);
169void		LibAliasSetTarget(struct libalias *, struct in_addr _target_addr);
170
171/* Transparent proxying routines. */
172int		LibAliasProxyRule(struct libalias *, const char *_cmd);
173
174
175/*
176 * Mode flags and other constants.
177 */
178
179
180/* Mode flags, set using PacketAliasSetMode() */
181
182/*
183 * If PKT_ALIAS_LOG is set, a message will be printed to /var/log/alias.log
184 * every time a link is created or deleted.  This is useful for debugging.
185 */
186#define	PKT_ALIAS_LOG			0x01
187
188/*
189 * If PKT_ALIAS_DENY_INCOMING is set, then incoming connections (e.g. to ftp,
190 * telnet or web servers will be prevented by the aliasing mechanism.
191 */
192#define	PKT_ALIAS_DENY_INCOMING		0x02
193
194/*
195 * If PKT_ALIAS_SAME_PORTS is set, packets will be attempted sent from the
196 * same port as they originated on.  This allows e.g. rsh to work *99% of the
197 * time*, but _not_ 100% (it will be slightly flakey instead of not working
198 * at all).  This mode bit is set by PacketAliasInit(), so it is a default
199 * mode of operation.
200 */
201#define	PKT_ALIAS_SAME_PORTS		0x04
202
203/*
204 * If PKT_ALIAS_USE_SOCKETS is set, then when partially specified links (e.g.
205 * destination port and/or address is zero), the packet aliasing engine will
206 * attempt to allocate a socket for the aliasing port it chooses.  This will
207 * avoid interference with the host machine.  Fully specified links do not
208 * require this.  This bit is set after a call to PacketAliasInit(), so it is
209 * a default mode of operation.
210 */
211#define	PKT_ALIAS_USE_SOCKETS		0x08
212
213/*-
214 * If PKT_ALIAS_UNREGISTERED_ONLY is set, then only packets with
215 * unregistered source addresses will be aliased.  Private
216 * addresses are those in the following ranges:
217 *
218 *		10.0.0.0     ->   10.255.255.255
219 *		172.16.0.0   ->   172.31.255.255
220 *		192.168.0.0  ->   192.168.255.255
221 */
222#define	PKT_ALIAS_UNREGISTERED_ONLY	0x10
223
224/*
225 * If PKT_ALIAS_RESET_ON_ADDR_CHANGE is set, then the table of dynamic
226 * aliasing links will be reset whenever PacketAliasSetAddress() changes the
227 * default aliasing address.  If the default aliasing address is left
228 * unchanged by this function call, then the table of dynamic aliasing links
229 * will be left intact.  This bit is set after a call to PacketAliasInit().
230 */
231#define	PKT_ALIAS_RESET_ON_ADDR_CHANGE	0x20
232
233#ifndef NO_FW_PUNCH
234/*
235 * If PKT_ALIAS_PUNCH_FW is set, active FTP and IRC DCC connections will
236 * create a 'hole' in the firewall to allow the transfers to work.  The
237 * ipfw rule number that the hole is created with is controlled by
238 * PacketAliasSetFWBase().  The hole will be attached to that
239 * particular alias_link, so when the link goes away the hole is deleted.
240 */
241#define	PKT_ALIAS_PUNCH_FW		0x100
242#endif
243
244/*
245 * If PKT_ALIAS_PROXY_ONLY is set, then NAT will be disabled and only
246 * transparent proxying is performed.
247 */
248#define	PKT_ALIAS_PROXY_ONLY		0x40
249
250/*
251 * If PKT_ALIAS_REVERSE is set, the actions of PacketAliasIn() and
252 * PacketAliasOut() are reversed.
253 */
254#define	PKT_ALIAS_REVERSE		0x80
255
256/* Function return codes. */
257#define	PKT_ALIAS_ERROR			-1
258#define	PKT_ALIAS_OK			1
259#define	PKT_ALIAS_IGNORED		2
260#define	PKT_ALIAS_UNRESOLVED_FRAGMENT	3
261#define	PKT_ALIAS_FOUND_HEADER_FRAGMENT	4
262
263#endif				/* !_ALIAS_H_ */
264
265/* lint -restore */
266