summaryrefslogtreecommitdiffstats
path: root/extensions/libxt_udp.c
blob: 4e83ae8f910c03a47620f79e745417d17555dfa4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
/* Shared library add-on to iptables to add UDP support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter/xt_tcpudp.h>

/* Function which prints out usage message. */
static void udp_help(void)
{
	printf(
"UDP v%s options:\n"
" --source-port [!] port[:port]\n"
" --sport ...\n"
"				match source port(s)\n"
" --destination-port [!] port[:port]\n"
" --dport ...\n"
"				match destination port(s)\n",
IPTABLES_VERSION);
}

static const struct option udp_opts[] = {
	{ "source-port", 1, NULL, '1' },
	{ "sport", 1, NULL, '1' }, /* synonym */
	{ "destination-port", 1, NULL, '2' },
	{ "dport", 1, NULL, '2' }, /* synonym */
	{ .name = NULL }
};

static void
parse_udp_ports(const char *portstring, u_int16_t *ports)
{
	char *buffer;
	char *cp;

	buffer = strdup(portstring);
	if ((cp = strchr(buffer, ':')) == NULL)
		ports[0] = ports[1] = parse_port(buffer, "udp");
	else {
		*cp = '\0';
		cp++;

		ports[0] = buffer[0] ? parse_port(buffer, "udp") : 0;
		ports[1] = cp[0] ? parse_port(cp, "udp") : 0xFFFF;

		if (ports[0] > ports[1])
			exit_error(PARAMETER_PROBLEM,
				   "invalid portrange (min > max)");
	}
	free(buffer);
}

/* Initialize the match. */
static void udp_init(struct xt_entry_match *m)
{
	struct xt_udp *udpinfo = (struct xt_udp *)m->data;

	udpinfo->spts[1] = udpinfo->dpts[1] = 0xFFFF;
}

#define UDP_SRC_PORTS 0x01
#define UDP_DST_PORTS 0x02

/* Function which parses command options; returns true if it
   ate an option */
static int
udp_parse(int c, char **argv, int invert, unsigned int *flags,
          const void *entry, struct xt_entry_match **match)
{
	struct xt_udp *udpinfo = (struct xt_udp *)(*match)->data;

	switch (c) {
	case '1':
		if (*flags & UDP_SRC_PORTS)
			exit_error(PARAMETER_PROBLEM,
				   "Only one `--source-port' allowed");
		check_inverse(optarg, &invert, &optind, 0);
		parse_udp_ports(argv[optind-1], udpinfo->spts);
		if (invert)
			udpinfo->invflags |= XT_UDP_INV_SRCPT;
		*flags |= UDP_SRC_PORTS;
		break;

	case '2':
		if (*flags & UDP_DST_PORTS)
			exit_error(PARAMETER_PROBLEM,
				   "Only one `--destination-port' allowed");
		check_inverse(optarg, &invert, &optind, 0);
		parse_udp_ports(argv[optind-1], udpinfo->dpts);
		if (invert)
			udpinfo->invflags |= XT_UDP_INV_DSTPT;
		*flags |= UDP_DST_PORTS;
		break;

	default:
		return 0;
	}

	return 1;
}

static char *
port_to_service(int port)
{
	struct servent *service;

	if ((service = getservbyport(htons(port), "udp")))
		return service->s_name;

	return NULL;
}

static void
print_port(u_int16_t port, int numeric)
{
	char *service;

	if (numeric || (service = port_to_service(port)) == NULL)
		printf("%u", port);
	else
		printf("%s", service);
}

static void
print_ports(const char *name, u_int16_t min, u_int16_t max,
	    int invert, int numeric)
{
	const char *inv = invert ? "!" : "";

	if (min != 0 || max != 0xFFFF || invert) {
		printf("%s", name);
		if (min == max) {
			printf(":%s", inv);
			print_port(min, numeric);
		} else {
			printf("s:%s", inv);
			print_port(min, numeric);
			printf(":");
			print_port(max, numeric);
		}
		printf(" ");
	}
}

/* Prints out the union ipt_matchinfo. */
static void
udp_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
	const struct xt_udp *udp = (struct xt_udp *)match->data;

	printf("udp ");
	print_ports("spt", udp->spts[0], udp->spts[1],
		    udp->invflags & XT_UDP_INV_SRCPT,
		    numeric);
	print_ports("dpt", udp->dpts[0], udp->dpts[1],
		    udp->invflags & XT_UDP_INV_DSTPT,
		    numeric);
	if (udp->invflags & ~XT_UDP_INV_MASK)
		printf("Unknown invflags: 0x%X ",
		       udp->invflags & ~XT_UDP_INV_MASK);
}

/* Saves the union ipt_matchinfo in parsable form to stdout. */
static void udp_save(const void *ip, const struct xt_entry_match *match)
{
	const struct xt_udp *udpinfo = (struct xt_udp *)match->data;

	if (udpinfo->spts[0] != 0
	    || udpinfo->spts[1] != 0xFFFF) {
		if (udpinfo->invflags & XT_UDP_INV_SRCPT)
			printf("! ");
		if (udpinfo->spts[0]
		    != udpinfo->spts[1])
			printf("--sport %u:%u ",
			       udpinfo->spts[0],
			       udpinfo->spts[1]);
		else
			printf("--sport %u ",
			       udpinfo->spts[0]);
	}

	if (udpinfo->dpts[0] != 0
	    || udpinfo->dpts[1] != 0xFFFF) {
		if (udpinfo->invflags & XT_UDP_INV_DSTPT)
			printf("! ");
		if (udpinfo->dpts[0]
		    != udpinfo->dpts[1])
			printf("--dport %u:%u ",
			       udpinfo->dpts[0],
			       udpinfo->dpts[1]);
		else
			printf("--dport %u ",
			       udpinfo->dpts[0]);
	}
}

static struct xtables_match udp_match = {
	.family		= AF_INET,
	.name		= "udp",
	.version	= IPTABLES_VERSION,
	.size		= XT_ALIGN(sizeof(struct xt_udp)),
	.userspacesize	= XT_ALIGN(sizeof(struct xt_udp)),
	.help		= udp_help,
	.init		= udp_init,
	.parse		= udp_parse,
	.print		= udp_print,
	.save		= udp_save,
	.extra_opts	= udp_opts,
};

static struct xtables_match udp_match6 = {
	.family		= AF_INET6,
	.name		= "udp",
	.version	= IPTABLES_VERSION,
	.size		= XT_ALIGN(sizeof(struct xt_udp)),
	.userspacesize	= XT_ALIGN(sizeof(struct xt_udp)),
	.help		= udp_help,
	.init		= udp_init,
	.parse		= udp_parse,
	.print		= udp_print,
	.save		= udp_save,
	.extra_opts	= udp_opts,
};

void
_init(void)
{
	xtables_register_match(&udp_match);
	xtables_register_match(&udp_match6);
}