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
44 * The kernel version of libalias does not support these features.
48 #define NO_USE_SOCKETS
52 * The external interface to libalias, the packet aliasing engine.
54 * There are two sets of functions:
56 * PacketAlias*() the old API which doesn't take an instance pointer
57 * and therefore can only have one packet engine at a time.
59 * LibAlias*() the new API which takes as first argument a pointer to
60 * the instance of the packet aliasing engine.
62 * The functions otherwise correspond to each other one for one, except
63 * for the LibAliasUnaliasOut()/PacketUnaliasOut() function which were
64 * were misnamed in the old API.
68 * The instance structure
73 * An anonymous structure, a pointer to which is returned from
74 * PacketAliasRedirectAddr(), PacketAliasRedirectPort() or
75 * PacketAliasRedirectProto(), passed to PacketAliasAddServer(),
76 * and freed by PacketAliasRedirectDelete().
83 /* Initialization and control functions. */
84 void PacketAliasInit(void);
85 void PacketAliasSetAddress(struct in_addr _addr);
86 void PacketAliasSetFWBase(unsigned int _base, unsigned int _num);
87 void PacketAliasSetSkinnyPort(unsigned int _port);
89 PacketAliasSetMode(unsigned int _flags, unsigned int _mask);
90 void PacketAliasUninit(void);
92 /* Packet Handling functions. */
93 int PacketAliasIn(char *_ptr, int _maxpacketsize);
94 int PacketAliasOut(char *_ptr, int _maxpacketsize);
95 int PacketUnaliasOut(char *_ptr, int _maxpacketsize);
97 /* Port and address redirection functions. */
101 PacketAliasAddServer(struct alias_link *_lnk,
102 struct in_addr _addr, unsigned short _port);
104 PacketAliasRedirectAddr(struct in_addr _src_addr,
105 struct in_addr _alias_addr);
106 int PacketAliasRedirectDynamic(struct alias_link *_lnk);
107 void PacketAliasRedirectDelete(struct alias_link *_lnk);
109 PacketAliasRedirectPort(struct in_addr _src_addr,
110 unsigned short _src_port, struct in_addr _dst_addr,
111 unsigned short _dst_port, struct in_addr _alias_addr,
112 unsigned short _alias_port, unsigned char _proto);
114 PacketAliasRedirectProto(struct in_addr _src_addr,
115 struct in_addr _dst_addr, struct in_addr _alias_addr,
116 unsigned char _proto);
118 /* Fragment Handling functions. */
119 void PacketAliasFragmentIn(char *_ptr, char *_ptr_fragment);
120 char *PacketAliasGetFragment(char *_ptr);
121 int PacketAliasSaveFragment(char *_ptr);
123 /* Miscellaneous functions. */
124 int PacketAliasCheckNewLink(void);
126 PacketAliasInternetChecksum(unsigned short *_ptr, int _nbytes);
127 void PacketAliasSetTarget(struct in_addr _target_addr);
129 /* Transparent proxying routines. */
130 int PacketAliasProxyRule(const char *_cmd);
134 /* Initialization and control functions. */
135 struct libalias *LibAliasInit(struct libalias *);
136 void LibAliasSetAddress(struct libalias *, struct in_addr _addr);
137 void LibAliasSetFWBase(struct libalias *, unsigned int _base, unsigned int _num);
138 void LibAliasSetSkinnyPort(struct libalias *, unsigned int _port);
140 LibAliasSetMode(struct libalias *, unsigned int _flags, unsigned int _mask);
141 void LibAliasUninit(struct libalias *);
143 /* Packet Handling functions. */
144 int LibAliasIn (struct libalias *, char *_ptr, int _maxpacketsize);
145 int LibAliasOut(struct libalias *, char *_ptr, int _maxpacketsize);
146 int LibAliasOutTry(struct libalias *, char *_ptr, int _maxpacketsize, int _create);
147 int LibAliasUnaliasOut(struct libalias *, char *_ptr, int _maxpacketsize);
149 /* Port and address redirection functions. */
152 LibAliasAddServer(struct libalias *, struct alias_link *_lnk,
153 struct in_addr _addr, unsigned short _port);
155 LibAliasRedirectAddr(struct libalias *, struct in_addr _src_addr,
156 struct in_addr _alias_addr);
157 int LibAliasRedirectDynamic(struct libalias *, struct alias_link *_lnk);
158 void LibAliasRedirectDelete(struct libalias *, struct alias_link *_lnk);
160 LibAliasRedirectPort(struct libalias *, struct in_addr _src_addr,
161 unsigned short _src_port, struct in_addr _dst_addr,
162 unsigned short _dst_port, struct in_addr _alias_addr,
163 unsigned short _alias_port, unsigned char _proto);
165 LibAliasRedirectProto(struct libalias *, struct in_addr _src_addr,
166 struct in_addr _dst_addr, struct in_addr _alias_addr,
167 unsigned char _proto);
169 /* Fragment Handling functions. */
170 void LibAliasFragmentIn(struct libalias *, char *_ptr, char *_ptr_fragment);
171 char *LibAliasGetFragment(struct libalias *, char *_ptr);
172 int LibAliasSaveFragment(struct libalias *, char *_ptr);
174 /* Miscellaneous functions. */
175 int LibAliasCheckNewLink(struct libalias *);
177 LibAliasInternetChecksum(struct libalias *, unsigned short *_ptr, int _nbytes);
178 void LibAliasSetTarget(struct libalias *, struct in_addr _target_addr);
180 /* Transparent proxying routines. */
181 int LibAliasProxyRule(struct libalias *, const char *_cmd);
185 * Mode flags and other constants.
189 /* Mode flags, set using PacketAliasSetMode() */
192 * If PKT_ALIAS_LOG is set, a message will be printed to /var/log/alias.log
193 * every time a link is created or deleted. This is useful for debugging.
196 #define PKT_ALIAS_LOG 0x01
200 * If PKT_ALIAS_DENY_INCOMING is set, then incoming connections (e.g. to ftp,
201 * telnet or web servers will be prevented by the aliasing mechanism.
203 #define PKT_ALIAS_DENY_INCOMING 0x02
206 * If PKT_ALIAS_SAME_PORTS is set, packets will be attempted sent from the
207 * same port as they originated on. This allows e.g. rsh to work *99% of the
208 * time*, but _not_ 100% (it will be slightly flakey instead of not working
209 * at all). This mode bit is set by PacketAliasInit(), so it is a default
212 #define PKT_ALIAS_SAME_PORTS 0x04
215 * If PKT_ALIAS_USE_SOCKETS is set, then when partially specified links (e.g.
216 * destination port and/or address is zero), the packet aliasing engine will
217 * attempt to allocate a socket for the aliasing port it chooses. This will
218 * avoid interference with the host machine. Fully specified links do not
219 * require this. This bit is set after a call to PacketAliasInit(), so it is
220 * a default mode of operation.
222 #ifndef NO_USE_SOCKETS
223 #define PKT_ALIAS_USE_SOCKETS 0x08
226 * If PKT_ALIAS_UNREGISTERED_ONLY is set, then only packets with
227 * unregistered source addresses will be aliased. Private
228 * addresses are those in the following ranges:
230 * 10.0.0.0 -> 10.255.255.255
231 * 172.16.0.0 -> 172.31.255.255
232 * 192.168.0.0 -> 192.168.255.255
234 #define PKT_ALIAS_UNREGISTERED_ONLY 0x10
237 * If PKT_ALIAS_RESET_ON_ADDR_CHANGE is set, then the table of dynamic
238 * aliasing links will be reset whenever PacketAliasSetAddress() changes the
239 * default aliasing address. If the default aliasing address is left
240 * unchanged by this function call, then the table of dynamic aliasing links
241 * will be left intact. This bit is set after a call to PacketAliasInit().
243 #define PKT_ALIAS_RESET_ON_ADDR_CHANGE 0x20
247 * If PKT_ALIAS_PUNCH_FW is set, active FTP and IRC DCC connections will
248 * create a 'hole' in the firewall to allow the transfers to work. The
249 * ipfw rule number that the hole is created with is controlled by
250 * PacketAliasSetFWBase(). The hole will be attached to that
251 * particular alias_link, so when the link goes away the hole is deleted.
253 #define PKT_ALIAS_PUNCH_FW 0x100
257 * If PKT_ALIAS_PROXY_ONLY is set, then NAT will be disabled and only
258 * transparent proxying is performed.
260 #define PKT_ALIAS_PROXY_ONLY 0x40
263 * If PKT_ALIAS_REVERSE is set, the actions of PacketAliasIn() and
264 * PacketAliasOut() are reversed.
266 #define PKT_ALIAS_REVERSE 0x80
268 /* Function return codes. */
269 #define PKT_ALIAS_ERROR -1
270 #define PKT_ALIAS_OK 1
271 #define PKT_ALIAS_IGNORED 2
272 #define PKT_ALIAS_UNRESOLVED_FRAGMENT 3
273 #define PKT_ALIAS_FOUND_HEADER_FRAGMENT 4
275 #endif /* !_ALIAS_H_ */