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
59static void
60AliasHandleDummy(struct libalias *la, struct ip *ip, struct alias_data *ah);
61
62static int
63fingerprint(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
86static int
87protohandler(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
101struct 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
112static int
113mod_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
133static
134#endif
135moduledata_t alias_mod = {
136       "alias_dummy", mod_handler, NULL
137};
138
139#ifdef _KERNEL
140DECLARE_MODULE(alias_dummy, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);
141MODULE_VERSION(alias_dummy, 1);
142MODULE_DEPEND(alias_dummy, libalias, 1, 1, 1);
143#endif
144
145static void
146AliasHandleDummy(struct libalias *la, struct ip *ip, struct alias_data *ah)
147{
148	; /* Dummy. */
149}
150