1 /* lint -save -library Flexelint comment for external headers */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-2-Clause 5 * 6 * Copyright (c) 2001 Charles Mott <cm@linktel.net> 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 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 #include <netinet/in_systm.h> 43 #include <netinet/in.h> 44 #include <netinet/ip.h> 45 46 #define LIBALIAS_BUF_SIZE 128 47 #ifdef _KERNEL 48 /* 49 * The kernel version of libalias does not support these features. 50 */ 51 #define NO_FW_PUNCH 52 #define NO_USE_SOCKETS 53 #endif 54 55 /* 56 * The external interface to libalias, the packet aliasing engine. 57 * 58 * There are two sets of functions: 59 * 60 * PacketAlias*() the old API which doesn't take an instance pointer 61 * and therefore can only have one packet engine at a time. 62 * 63 * LibAlias*() the new API which takes as first argument a pointer to 64 * the instance of the packet aliasing engine. 65 * 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. 69 */ 70 71 /* 72 * The instance structure 73 */ 74 struct libalias; 75 76 /* 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(). 81 */ 82 struct alias_link; 83 84 /* Initialization and control functions. */ 85 struct libalias *LibAliasInit(struct libalias *); 86 void LibAliasSetAddress(struct libalias *, struct in_addr _addr); 87 void LibAliasSetAliasPortRange(struct libalias *la, u_short port_low, u_short port_hi); 88 void LibAliasSetFWBase(struct libalias *, unsigned int _base, unsigned int _num); 89 void LibAliasSetSkinnyPort(struct libalias *, unsigned int _port); 90 unsigned int LibAliasSetMode(struct libalias *, unsigned int _flags, unsigned int _mask); 91 void LibAliasUninit(struct libalias *); 92 93 /* Packet Handling functions. */ 94 int LibAliasIn (struct libalias *, void *_ptr, int _maxpacketsize); 95 int LibAliasOut(struct libalias *, void *_ptr, int _maxpacketsize); 96 int LibAliasOutTry(struct libalias *, void *_ptr, int _maxpacketsize, int _create); 97 int LibAliasUnaliasOut(struct libalias *, void *_ptr, int _maxpacketsize); 98 99 /* Port and address redirection functions. */ 100 101 int LibAliasAddServer(struct libalias *, struct alias_link *_lnk, 102 struct in_addr _addr, unsigned short _port); 103 struct alias_link * LibAliasRedirectAddr(struct libalias *, struct in_addr _src_addr, 104 struct in_addr _alias_addr); 105 int LibAliasRedirectDynamic(struct libalias *, struct alias_link *_lnk); 106 void LibAliasRedirectDelete(struct libalias *, struct alias_link *_lnk); 107 struct alias_link * LibAliasRedirectPort(struct libalias *, struct in_addr _src_addr, 108 unsigned short _src_port, struct in_addr _dst_addr, 109 unsigned short _dst_port, struct in_addr _alias_addr, 110 unsigned short _alias_port, unsigned char _proto); 111 struct alias_link * LibAliasRedirectProto(struct libalias *, struct in_addr _src_addr, 112 struct in_addr _dst_addr, struct in_addr _alias_addr, 113 unsigned char _proto); 114 115 /* Fragment Handling functions. */ 116 void LibAliasFragmentIn(struct libalias *, void *_ptr, void *_ptr_fragment); 117 void *LibAliasGetFragment(struct libalias *, void *_ptr); 118 int LibAliasSaveFragment(struct libalias *, void *_ptr); 119 120 /* Miscellaneous functions. */ 121 unsigned short LibAliasInternetChecksum(struct libalias *, unsigned short *_ptr, int _nbytes); 122 void LibAliasSetTarget(struct libalias *, struct in_addr _target_addr); 123 124 /* Transparent proxying routines. */ 125 int LibAliasProxyRule(struct libalias *, const char *_cmd); 126 127 /* Module handling API */ 128 int LibAliasLoadModule(char *); 129 int LibAliasUnLoadAllModule(void); 130 int LibAliasRefreshModules(void); 131 132 /* Mbuf helper function. */ 133 struct mbuf *m_megapullup(struct mbuf *, int); 134 135 /* 136 * Mode flags and other constants. 137 */ 138 139 /* Mode flags, set using PacketAliasSetMode() */ 140 141 /* 142 * If PKT_ALIAS_LOG is set, a message will be printed to /var/log/alias.log 143 * every time a link is created or deleted. This is useful for debugging. 144 */ 145 #define PKT_ALIAS_LOG 0x01 146 147 /* 148 * If PKT_ALIAS_DENY_INCOMING is set, then incoming connections (e.g. to ftp, 149 * telnet or web servers will be prevented by the aliasing mechanism. 150 */ 151 #define PKT_ALIAS_DENY_INCOMING 0x02 152 153 /* 154 * If PKT_ALIAS_SAME_PORTS is set, packets will be attempted sent from the 155 * same port as they originated on. This allows e.g. rsh to work *99% of the 156 * time*, but _not_ 100% (it will be slightly flakey instead of not working 157 * at all). This mode bit is set by PacketAliasInit(), so it is a default 158 * mode of operation. 159 */ 160 #define PKT_ALIAS_SAME_PORTS 0x04 161 162 /* 163 * If PKT_ALIAS_USE_SOCKETS is set, then when partially specified links (e.g. 164 * destination port and/or address is zero), the packet aliasing engine will 165 * attempt to allocate a socket for the aliasing port it chooses. This will 166 * avoid interference with the host machine. Fully specified links do not 167 * require this. This bit is set after a call to PacketAliasInit(), so it is 168 * a default mode of operation. 169 */ 170 #ifndef NO_USE_SOCKETS 171 #define PKT_ALIAS_USE_SOCKETS 0x08 172 #endif 173 /*- 174 * If PKT_ALIAS_UNREGISTERED_ONLY is set, then only packets with 175 * unregistered source addresses will be aliased. Private 176 * addresses are those in the following ranges: 177 * 178 * 10.0.0.0 -> 10.255.255.255 179 * 172.16.0.0 -> 172.31.255.255 180 * 192.168.0.0 -> 192.168.255.255 181 */ 182 #define PKT_ALIAS_UNREGISTERED_ONLY 0x10 183 184 /* 185 * If PKT_ALIAS_RESET_ON_ADDR_CHANGE is set, then the table of dynamic 186 * aliasing links will be reset whenever PacketAliasSetAddress() changes the 187 * default aliasing address. If the default aliasing address is left 188 * unchanged by this function call, then the table of dynamic aliasing links 189 * will be left intact. This bit is set after a call to PacketAliasInit(). 190 */ 191 #define PKT_ALIAS_RESET_ON_ADDR_CHANGE 0x20 192 193 /* 194 * If PKT_ALIAS_PROXY_ONLY is set, then NAT will be disabled and only 195 * transparent proxying is performed. 196 */ 197 #define PKT_ALIAS_PROXY_ONLY 0x40 198 199 /* 200 * If PKT_ALIAS_REVERSE is set, the actions of PacketAliasIn() and 201 * PacketAliasOut() are reversed. 202 */ 203 #define PKT_ALIAS_REVERSE 0x80 204 205 #ifndef NO_FW_PUNCH 206 /* 207 * If PKT_ALIAS_PUNCH_FW is set, active FTP and IRC DCC connections will 208 * create a 'hole' in the firewall to allow the transfers to work. The 209 * ipfw rule number that the hole is created with is controlled by 210 * PacketAliasSetFWBase(). The hole will be attached to that 211 * particular alias_link, so when the link goes away the hole is deleted. 212 */ 213 #define PKT_ALIAS_PUNCH_FW 0x100 214 #endif 215 216 /* 217 * If PKT_ALIAS_SKIP_GLOBAL is set, nat instance is not checked for matching 218 * states in 'ipfw nat global' rule. 219 */ 220 #define PKT_ALIAS_SKIP_GLOBAL 0x200 221 222 /* 223 * Like PKT_ALIAS_UNREGISTERED_ONLY, but includes the RFC 6598 224 * (Carrier Grade NAT) address range as follows: 225 * 226 * 100.64.0.0 -> 100.127.255.255 227 */ 228 #define PKT_ALIAS_UNREGISTERED_CGN 0x400 229 230 /* 231 * When this bit is set, UDP uses endpoint-independent mapping (EIM), as per 232 * RFC 4787 ("full cone" NAT of RFC 3489). All packets from the same internal 233 * address:port are mapped to the same NAT address:port, regardless of their 234 * destination address:port. If filtering rules allow, and if 235 * PKT_ALIAS_DENY_INCOMING is unset, any other external address:port can also 236 * send to the internal address:port through its mapped NAT address:port. This 237 * is more compatible with applications, and can reduce the need for port 238 * forwarding, but less scalable as each NAT address:port can only be 239 * concurrently used by at most one internal address:port. 240 * 241 * When this bit is unset, UDP packets use endpoint-dependent mapping (EDM) 242 * ("symmetric" NAT). Each connection from a particular internal address:port 243 * to different external addresses:ports is mapped to a random and 244 * unpredictable NAT address:port. Two appplications behind EDM NATs can only 245 * connect to each other by port forwarding on the NAT, or tunnelling through 246 * an in-between server. 247 */ 248 #define PKT_ALIAS_UDP_EIM 0x800 249 250 /* Function return codes. */ 251 #define PKT_ALIAS_ERROR -1 252 #define PKT_ALIAS_OK 1 253 #define PKT_ALIAS_IGNORED 2 254 #define PKT_ALIAS_UNRESOLVED_FRAGMENT 3 255 #define PKT_ALIAS_FOUND_HEADER_FRAGMENT 4 256 257 #endif /* !_ALIAS_H_ */ 258 259 /* lint -restore */ 260