1 /* lint -save -library Flexelint comment for external headers */
4 * Copyright (c) 2001 Charles Mott <cm@linktel.net>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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.
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
32 * Alias.h defines the outside world interfaces for the packet aliasing
35 * This software is placed into the public domain with no restrictions on its
42 #include <netinet/in_systm.h>
43 #include <netinet/in.h>
44 #include <netinet/ip.h>
46 #define LIBALIAS_BUF_SIZE 128
49 * The kernel version of libalias does not support these features.
52 #define NO_USE_SOCKETS
56 * The external interface to libalias, the packet aliasing engine.
58 * There are two sets of functions:
60 * PacketAlias*() the old API which doesn't take an instance pointer
61 * and therefore can only have one packet engine at a time.
63 * LibAlias*() the new API which takes as first argument a pointer to
64 * the instance of the packet aliasing engine.
66 * The functions otherwise correspond to each other one for one, except
67 * for the LibAliasUnaliasOut()/PacketUnaliasOut() function which were
68 * were misnamed in the old API.
72 * The instance structure
77 * An anonymous structure, a pointer to which is returned from
78 * PacketAliasRedirectAddr(), PacketAliasRedirectPort() or
79 * PacketAliasRedirectProto(), passed to PacketAliasAddServer(),
80 * and freed by PacketAliasRedirectDelete().
87 /* Initialization and control functions. */
88 void PacketAliasInit(void);
89 void PacketAliasSetAddress(struct in_addr _addr);
90 void PacketAliasSetFWBase(unsigned int _base, unsigned int _num);
91 void PacketAliasSetSkinnyPort(unsigned int _port);
93 PacketAliasSetMode(unsigned int _flags, unsigned int _mask);
94 void PacketAliasUninit(void);
96 /* Packet Handling functions. */
97 int PacketAliasIn(char *_ptr, int _maxpacketsize);
98 int PacketAliasOut(char *_ptr, int _maxpacketsize);
99 int PacketUnaliasOut(char *_ptr, int _maxpacketsize);
101 /* Port and address redirection functions. */
105 PacketAliasAddServer(struct alias_link *_lnk,
106 struct in_addr _addr, unsigned short _port);
108 PacketAliasRedirectAddr(struct in_addr _src_addr,
109 struct in_addr _alias_addr);
110 int PacketAliasRedirectDynamic(struct alias_link *_lnk);
111 void PacketAliasRedirectDelete(struct alias_link *_lnk);
113 PacketAliasRedirectPort(struct in_addr _src_addr,
114 unsigned short _src_port, struct in_addr _dst_addr,
115 unsigned short _dst_port, struct in_addr _alias_addr,
116 unsigned short _alias_port, unsigned char _proto);
118 PacketAliasRedirectProto(struct in_addr _src_addr,
119 struct in_addr _dst_addr, struct in_addr _alias_addr,
120 unsigned char _proto);
122 /* Fragment Handling functions. */
123 void PacketAliasFragmentIn(char *_ptr, char *_ptr_fragment);
124 char *PacketAliasGetFragment(char *_ptr);
125 int PacketAliasSaveFragment(char *_ptr);
127 /* Miscellaneous functions. */
128 int PacketAliasCheckNewLink(void);
130 PacketAliasInternetChecksum(unsigned short *_ptr, int _nbytes);
131 void PacketAliasSetTarget(struct in_addr _target_addr);
133 /* Transparent proxying routines. */
134 int PacketAliasProxyRule(const char *_cmd);
138 /* Initialization and control functions. */
139 struct libalias *LibAliasInit(struct libalias *);
140 void LibAliasSetAddress(struct libalias *, struct in_addr _addr);
141 void LibAliasSetFWBase(struct libalias *, unsigned int _base, unsigned int _num);
142 void LibAliasSetSkinnyPort(struct libalias *, unsigned int _port);
144 LibAliasSetMode(struct libalias *, unsigned int _flags, unsigned int _mask);
145 void LibAliasUninit(struct libalias *);
147 /* Packet Handling functions. */
148 int LibAliasIn (struct libalias *, char *_ptr, int _maxpacketsize);
149 int LibAliasOut(struct libalias *, char *_ptr, int _maxpacketsize);
150 int LibAliasOutTry(struct libalias *, char *_ptr, int _maxpacketsize, int _create);
151 int LibAliasUnaliasOut(struct libalias *, char *_ptr, int _maxpacketsize);
153 /* Port and address redirection functions. */
156 LibAliasAddServer(struct libalias *, struct alias_link *_lnk,
157 struct in_addr _addr, unsigned short _port);
159 LibAliasRedirectAddr(struct libalias *, struct in_addr _src_addr,
160 struct in_addr _alias_addr);
161 int LibAliasRedirectDynamic(struct libalias *, struct alias_link *_lnk);
162 void LibAliasRedirectDelete(struct libalias *, struct alias_link *_lnk);
164 LibAliasRedirectPort(struct libalias *, struct in_addr _src_addr,
165 unsigned short _src_port, struct in_addr _dst_addr,
166 unsigned short _dst_port, struct in_addr _alias_addr,
167 unsigned short _alias_port, unsigned char _proto);
169 LibAliasRedirectProto(struct libalias *, struct in_addr _src_addr,
170 struct in_addr _dst_addr, struct in_addr _alias_addr,
171 unsigned char _proto);
173 /* Fragment Handling functions. */
174 void LibAliasFragmentIn(struct libalias *, char *_ptr, char *_ptr_fragment);
175 char *LibAliasGetFragment(struct libalias *, char *_ptr);
176 int LibAliasSaveFragment(struct libalias *, char *_ptr);
178 /* Miscellaneous functions. */
179 int LibAliasCheckNewLink(struct libalias *);
181 LibAliasInternetChecksum(struct libalias *, unsigned short *_ptr, int _nbytes);
182 void LibAliasSetTarget(struct libalias *, struct in_addr _target_addr);
184 /* Transparent proxying routines. */
185 int LibAliasProxyRule(struct libalias *, const char *_cmd);
187 /* Module handling API */
188 int LibAliasLoadModule(char *);
189 int LibAliasUnLoadAllModule(void);
190 int LibAliasRefreshModules(void);
193 * Mode flags and other constants.
197 /* Mode flags, set using PacketAliasSetMode() */
200 * If PKT_ALIAS_LOG is set, a message will be printed to /var/log/alias.log
201 * every time a link is created or deleted. This is useful for debugging.
203 #define PKT_ALIAS_LOG 0x01
206 * If PKT_ALIAS_DENY_INCOMING is set, then incoming connections (e.g. to ftp,
207 * telnet or web servers will be prevented by the aliasing mechanism.
209 #define PKT_ALIAS_DENY_INCOMING 0x02
212 * If PKT_ALIAS_SAME_PORTS is set, packets will be attempted sent from the
213 * same port as they originated on. This allows e.g. rsh to work *99% of the
214 * time*, but _not_ 100% (it will be slightly flakey instead of not working
215 * at all). This mode bit is set by PacketAliasInit(), so it is a default
218 #define PKT_ALIAS_SAME_PORTS 0x04
221 * If PKT_ALIAS_USE_SOCKETS is set, then when partially specified links (e.g.
222 * destination port and/or address is zero), the packet aliasing engine will
223 * attempt to allocate a socket for the aliasing port it chooses. This will
224 * avoid interference with the host machine. Fully specified links do not
225 * require this. This bit is set after a call to PacketAliasInit(), so it is
226 * a default mode of operation.
228 #ifndef NO_USE_SOCKETS
229 #define PKT_ALIAS_USE_SOCKETS 0x08
232 * If PKT_ALIAS_UNREGISTERED_ONLY is set, then only packets with
233 * unregistered source addresses will be aliased. Private
234 * addresses are those in the following ranges:
236 * 10.0.0.0 -> 10.255.255.255
237 * 172.16.0.0 -> 172.31.255.255
238 * 192.168.0.0 -> 192.168.255.255
240 #define PKT_ALIAS_UNREGISTERED_ONLY 0x10
243 * If PKT_ALIAS_RESET_ON_ADDR_CHANGE is set, then the table of dynamic
244 * aliasing links will be reset whenever PacketAliasSetAddress() changes the
245 * default aliasing address. If the default aliasing address is left
246 * unchanged by this function call, then the table of dynamic aliasing links
247 * will be left intact. This bit is set after a call to PacketAliasInit().
249 #define PKT_ALIAS_RESET_ON_ADDR_CHANGE 0x20
253 * If PKT_ALIAS_PUNCH_FW is set, active FTP and IRC DCC connections will
254 * create a 'hole' in the firewall to allow the transfers to work. The
255 * ipfw rule number that the hole is created with is controlled by
256 * PacketAliasSetFWBase(). The hole will be attached to that
257 * particular alias_link, so when the link goes away the hole is deleted.
259 #define PKT_ALIAS_PUNCH_FW 0x100
263 * If PKT_ALIAS_PROXY_ONLY is set, then NAT will be disabled and only
264 * transparent proxying is performed.
266 #define PKT_ALIAS_PROXY_ONLY 0x40
269 * If PKT_ALIAS_REVERSE is set, the actions of PacketAliasIn() and
270 * PacketAliasOut() are reversed.
272 #define PKT_ALIAS_REVERSE 0x80
274 /* Function return codes. */
275 #define PKT_ALIAS_ERROR -1
276 #define PKT_ALIAS_OK 1
277 #define PKT_ALIAS_IGNORED 2
278 #define PKT_ALIAS_UNRESOLVED_FRAGMENT 3
279 #define PKT_ALIAS_FOUND_HEADER_FRAGMENT 4
281 #endif /* !_ALIAS_H_ */