1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2005 Paolo Pisati <piso@FreeBSD.org> 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 29 #include <sys/cdefs.h> 30 /* 31 * Alias_dummy is just an empty skeleton used to demostrate how to write 32 * a module for libalias, that will run unalterated in userland or in 33 * kernel land. 34 */ 35 36 #ifdef _KERNEL 37 #include <sys/param.h> 38 #include <sys/kernel.h> 39 #include <sys/module.h> 40 #else 41 #include <errno.h> 42 #include <sys/types.h> 43 #include <stdio.h> 44 #endif 45 46 #include <netinet/in_systm.h> 47 #include <netinet/in.h> 48 #include <netinet/ip.h> 49 #include <netinet/udp.h> 50 51 #ifdef _KERNEL 52 #include <netinet/libalias/alias_local.h> 53 #include <netinet/libalias/alias_mod.h> 54 #else 55 #include "alias_local.h" 56 #include "alias_mod.h" 57 #endif 58 59 static void 60 AliasHandleDummy(struct libalias *la, struct ip *ip, struct alias_data *ah); 61 62 static int 63 fingerprint(struct libalias *la, struct alias_data *ah) 64 { 65 /* 66 * Check here all the data that will be used later, if any field 67 * is empy/NULL, return a -1 value. 68 */ 69 if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL || 70 ah->maxpktsize == 0) 71 return (-1); 72 /* 73 * Fingerprint the incoming packet, if it matches any conditions 74 * return an OK value. 75 */ 76 if (ntohs(*ah->dport) == 123 || ntohs(*ah->sport) == 456) 77 return (0); /* I know how to handle it. */ 78 return (-1); /* I don't recognize this packet. */ 79 } 80 81 /* 82 * Wrap in this general purpose function, the real function used to alias the 83 * packets. 84 */ 85 86 static int 87 protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah) 88 { 89 AliasHandleDummy(la, pip, ah); 90 return (0); 91 } 92 93 /* 94 * NOTA BENE: the next variable MUST NOT be renamed in any case if you want 95 * your module to work in userland, cause it's used to find and use all 96 * the protocol handlers present in every module. 97 * So WATCH OUT, your module needs this variables and it needs it with 98 * ITS EXACT NAME: handlers. 99 */ 100 101 struct proto_handler handlers [] = { 102 { 103 .pri = 666, 104 .dir = IN|OUT, 105 .proto = UDP|TCP, 106 .fingerprint = &fingerprint, 107 .protohandler = &protohandler 108 }, 109 { EOH } 110 }; 111 112 static int 113 mod_handler(module_t mod, int type, void *data) 114 { 115 int error; 116 117 switch (type) { 118 case MOD_LOAD: 119 error = 0; 120 LibAliasAttachHandlers(handlers); 121 break; 122 case MOD_UNLOAD: 123 error = 0; 124 LibAliasDetachHandlers(handlers); 125 break; 126 default: 127 error = EINVAL; 128 } 129 return (error); 130 } 131 132 #ifdef _KERNEL 133 static 134 #endif 135 moduledata_t alias_mod = { 136 "alias_dummy", mod_handler, NULL 137 }; 138 139 #ifdef _KERNEL 140 DECLARE_MODULE(alias_dummy, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND); 141 MODULE_VERSION(alias_dummy, 1); 142 MODULE_DEPEND(alias_dummy, libalias, 1, 1, 1); 143 #endif 144 145 static void 146 AliasHandleDummy(struct libalias *la, struct ip *ip, struct alias_data *ah) 147 { 148 ; /* Dummy. */ 149 } 150