1/*
2 * Shared library add-on to iptables to match
3 * packets by their type (BROADCAST, UNICAST, MULTICAST).
4 *
5 * Michal Ludvig <michal@logix.cz>
6 */
7#include <stdio.h>
8#include <string.h>
9#include <xtables.h>
10#include <linux/if_packet.h>
11#include <linux/netfilter/xt_pkttype.h>
12
13enum {
14	O_PKTTYPE = 0,
15};
16
17struct pkttypes {
18	const char *name;
19	unsigned char pkttype;
20	unsigned char printhelp;
21	const char *help;
22};
23
24struct pkttypes_xlate {
25	const char *name;
26	unsigned char pkttype;
27};
28
29static const struct pkttypes supported_types[] = {
30	{"unicast", PACKET_HOST, 1, "to us"},
31	{"broadcast", PACKET_BROADCAST, 1, "to all"},
32	{"multicast", PACKET_MULTICAST, 1, "to group"},
33/*
34	{"otherhost", PACKET_OTHERHOST, 1, "to someone else"},
35	{"outgoing", PACKET_OUTGOING, 1, "outgoing of any type"},
36*/
37	/* aliases */
38	{"bcast", PACKET_BROADCAST, 0, NULL},
39	{"mcast", PACKET_MULTICAST, 0, NULL},
40	{"host", PACKET_HOST, 0, NULL}
41};
42
43static void print_types(void)
44{
45	unsigned int	i;
46
47	printf("Valid packet types:\n");
48	for (i = 0; i < ARRAY_SIZE(supported_types); ++i)
49		if(supported_types[i].printhelp == 1)
50			printf("\t%-14s\t\t%s\n", supported_types[i].name, supported_types[i].help);
51	printf("\n");
52}
53
54static void pkttype_help(void)
55{
56	printf(
57"pkttype match options:\n"
58"[!] --pkt-type packettype    match packet type\n");
59	print_types();
60}
61
62static const struct xt_option_entry pkttype_opts[] = {
63	{.name = "pkt-type", .id = O_PKTTYPE, .type = XTTYPE_STRING,
64	 .flags = XTOPT_MAND | XTOPT_INVERT},
65	XTOPT_TABLEEND,
66};
67
68static void parse_pkttype(const char *pkttype, struct xt_pkttype_info *info)
69{
70	unsigned int	i;
71
72	for (i = 0; i < ARRAY_SIZE(supported_types); ++i)
73		if(strcasecmp(pkttype, supported_types[i].name)==0)
74		{
75			info->pkttype=supported_types[i].pkttype;
76			return;
77		}
78
79	xtables_error(PARAMETER_PROBLEM, "Bad packet type '%s'", pkttype);
80}
81
82static void pkttype_parse(struct xt_option_call *cb)
83{
84	struct xt_pkttype_info *info = cb->data;
85
86	xtables_option_parse(cb);
87	parse_pkttype(cb->arg, info);
88	if (cb->invert)
89		info->invert = 1;
90}
91
92static void print_pkttype(const struct xt_pkttype_info *info)
93{
94	unsigned int	i;
95
96	for (i = 0; i < ARRAY_SIZE(supported_types); ++i)
97		if(supported_types[i].pkttype==info->pkttype)
98		{
99			printf("%s", supported_types[i].name);
100			return;
101		}
102
103	printf("%d", info->pkttype);	/* in case we didn't find an entry in named-packtes */
104}
105
106static void pkttype_print(const void *ip, const struct xt_entry_match *match,
107                          int numeric)
108{
109	const struct xt_pkttype_info *info = (const void *)match->data;
110
111	printf(" PKTTYPE %s= ", info->invert ? "!" : "");
112	print_pkttype(info);
113}
114
115static void pkttype_save(const void *ip, const struct xt_entry_match *match)
116{
117	const struct xt_pkttype_info *info = (const void *)match->data;
118
119	printf("%s --pkt-type ", info->invert ? " !" : "");
120	print_pkttype(info);
121}
122
123static const struct pkttypes_xlate supported_types_xlate[] = {
124	{"unicast",	PACKET_HOST},
125	{"broadcast",	PACKET_BROADCAST},
126	{"multicast",	PACKET_MULTICAST},
127};
128
129static void print_pkttype_xlate(const struct xt_pkttype_info *info,
130				struct xt_xlate *xl)
131{
132	unsigned int i;
133
134	for (i = 0; i < ARRAY_SIZE(supported_types_xlate); ++i) {
135		if (supported_types_xlate[i].pkttype == info->pkttype) {
136			xt_xlate_add(xl, "%s", supported_types_xlate[i].name);
137			return;
138		}
139	}
140	xt_xlate_add(xl, "%d", info->pkttype);
141}
142
143static int pkttype_xlate(struct xt_xlate *xl,
144			 const struct xt_xlate_mt_params *params)
145{
146	const struct xt_pkttype_info *info = (const void *)params->match->data;
147
148	xt_xlate_add(xl, "pkttype%s ", info->invert ? " !=" : "");
149	print_pkttype_xlate(info, xl);
150
151	return 1;
152}
153
154static struct xtables_match pkttype_match = {
155	.family		= NFPROTO_UNSPEC,
156	.name		= "pkttype",
157	.version	= XTABLES_VERSION,
158	.size		= XT_ALIGN(sizeof(struct xt_pkttype_info)),
159	.userspacesize	= XT_ALIGN(sizeof(struct xt_pkttype_info)),
160	.help		= pkttype_help,
161	.print		= pkttype_print,
162	.save		= pkttype_save,
163	.x6_parse	= pkttype_parse,
164	.x6_options	= pkttype_opts,
165	.xlate		= pkttype_xlate,
166};
167
168void _init(void)
169{
170	xtables_register_match(&pkttype_match);
171}
172