1 /*- 2 * Copyright (c) 2005 Paolo Pisati <piso@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 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 ip *pip, struct alias_data *ah) 64 { 65 66 /* 67 * Check here all the data that will be used later, if any field 68 * is empy/NULL, return a -1 value. 69 */ 70 if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL || 71 ah->maxpktsize == 0) 72 return (-1); 73 /* 74 * Fingerprint the incoming packet, if it matches any conditions 75 * return an OK value. 76 */ 77 if (ntohs(*ah->dport) == 123 78 || ntohs(*ah->sport) == 456) 79 return (0); /* I know how to handle it. */ 80 return (-1); /* I don't recognize this packet. */ 81 } 82 83 /* 84 * Wrap in this general purpose function, the real function used to alias the 85 * packets. 86 */ 87 88 static int 89 protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah) 90 { 91 92 AliasHandleDummy(la, pip, ah); 93 return (0); 94 } 95 96 /* 97 * NOTA BENE: the next variable MUST NOT be renamed in any case if you want 98 * your module to work in userland, cause it's used to find and use all 99 * the protocol handlers present in every module. 100 * So WATCH OUT, your module needs this variables and it needs it with 101 * ITS EXACT NAME: handlers. 102 */ 103 104 struct proto_handler handlers [] = { 105 { 106 .pri = 666, 107 .dir = IN|OUT, 108 .proto = UDP|TCP, 109 .fingerprint = &fingerprint, 110 .protohandler = &protohandler 111 }, 112 { EOH } 113 }; 114 115 static int 116 mod_handler(module_t mod, int type, void *data) 117 { 118 int error; 119 120 switch (type) { 121 case MOD_LOAD: 122 error = 0; 123 LibAliasAttachHandlers(handlers); 124 break; 125 case MOD_UNLOAD: 126 error = 0; 127 LibAliasDetachHandlers(handlers); 128 break; 129 default: 130 error = EINVAL; 131 } 132 return (error); 133 } 134 135 #ifdef _KERNEL 136 static 137 #endif 138 moduledata_t alias_mod = { 139 "alias_dummy", mod_handler, NULL 140 }; 141 142 #ifdef _KERNEL 143 DECLARE_MODULE(alias_dummy, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND); 144 MODULE_VERSION(alias_dummy, 1); 145 MODULE_DEPEND(alias_dummy, libalias, 1, 1, 1); 146 #endif 147 148 static void 149 AliasHandleDummy(struct libalias *la, struct ip *ip, struct alias_data *ah) 150 { 151 ; /* Dummy. */ 152 } 153 154