libxt_udp.c revision 830132ac9c0d270bf9dcfe85c2464e3fe8c73fb9 
1/* Shared library add-on to iptables to add UDP support. */
2#include <stdio.h>
3#include <netdb.h>
4#include <string.h>
5#include <stdlib.h>
6#include <getopt.h>
7#include <xtables.h>
8#include <linux/netfilter/xt_tcpudp.h>
9
10/* Function which prints out usage message. */
11static void
12help(void)
13{
14	printf(
15"UDP v%s options:\n"
16" --source-port [!] port[:port]\n"
17" --sport ...\n"
18"				match source port(s)\n"
19" --destination-port [!] port[:port]\n"
20" --dport ...\n"
21"				match destination port(s)\n",
22IPTABLES_VERSION);
23}
24
25static const struct option opts[] = {
26	{ "source-port", 1, NULL, '1' },
27	{ "sport", 1, NULL, '1' }, /* synonym */
28	{ "destination-port", 1, NULL, '2' },
29	{ "dport", 1, NULL, '2' }, /* synonym */
30	{ }
31};
32
33static void
34parse_udp_ports(const char *portstring, u_int16_t *ports)
35{
36	char *buffer;
37	char *cp;
38
39	buffer = strdup(portstring);
40	if ((cp = strchr(buffer, ':')) == NULL)
41		ports[0] = ports[1] = parse_port(buffer, "udp");
42	else {
43		*cp = '\0';
44		cp++;
45
46		ports[0] = buffer[0] ? parse_port(buffer, "udp") : 0;
47		ports[1] = cp[0] ? parse_port(cp, "udp") : 0xFFFF;
48
49		if (ports[0] > ports[1])
50			exit_error(PARAMETER_PROBLEM,
51				   "invalid portrange (min > max)");
52	}
53	free(buffer);
54}
55
56/* Initialize the match. */
57static void
58init(struct xt_entry_match *m)
59{
60	struct xt_udp *udpinfo = (struct xt_udp *)m->data;
61
62	udpinfo->spts[1] = udpinfo->dpts[1] = 0xFFFF;
63}
64
65#define UDP_SRC_PORTS 0x01
66#define UDP_DST_PORTS 0x02
67
68/* Function which parses command options; returns true if it
69   ate an option */
70static int
71parse(int c, char **argv, int invert, unsigned int *flags,
72      const void *entry,
73      struct xt_entry_match **match)
74{
75	struct xt_udp *udpinfo = (struct xt_udp *)(*match)->data;
76
77	switch (c) {
78	case '1':
79		if (*flags & UDP_SRC_PORTS)
80			exit_error(PARAMETER_PROBLEM,
81				   "Only one `--source-port' allowed");
82		check_inverse(optarg, &invert, &optind, 0);
83		parse_udp_ports(argv[optind-1], udpinfo->spts);
84		if (invert)
85			udpinfo->invflags |= XT_UDP_INV_SRCPT;
86		*flags |= UDP_SRC_PORTS;
87		break;
88
89	case '2':
90		if (*flags & UDP_DST_PORTS)
91			exit_error(PARAMETER_PROBLEM,
92				   "Only one `--destination-port' allowed");
93		check_inverse(optarg, &invert, &optind, 0);
94		parse_udp_ports(argv[optind-1], udpinfo->dpts);
95		if (invert)
96			udpinfo->invflags |= XT_UDP_INV_DSTPT;
97		*flags |= UDP_DST_PORTS;
98		break;
99
100	default:
101		return 0;
102	}
103
104	return 1;
105}
106
107static char *
108port_to_service(int port)
109{
110	struct servent *service;
111
112	if ((service = getservbyport(htons(port), "udp")))
113		return service->s_name;
114
115	return NULL;
116}
117
118static void
119print_port(u_int16_t port, int numeric)
120{
121	char *service;
122
123	if (numeric || (service = port_to_service(port)) == NULL)
124		printf("%u", port);
125	else
126		printf("%s", service);
127}
128
129static void
130print_ports(const char *name, u_int16_t min, u_int16_t max,
131	    int invert, int numeric)
132{
133	const char *inv = invert ? "!" : "";
134
135	if (min != 0 || max != 0xFFFF || invert) {
136		printf("%s", name);
137		if (min == max) {
138			printf(":%s", inv);
139			print_port(min, numeric);
140		} else {
141			printf("s:%s", inv);
142			print_port(min, numeric);
143			printf(":");
144			print_port(max, numeric);
145		}
146		printf(" ");
147	}
148}
149
150/* Prints out the union ipt_matchinfo. */
151static void
152print(const void *ip,
153      const struct xt_entry_match *match, int numeric)
154{
155	const struct xt_udp *udp = (struct xt_udp *)match->data;
156
157	printf("udp ");
158	print_ports("spt", udp->spts[0], udp->spts[1],
159		    udp->invflags & XT_UDP_INV_SRCPT,
160		    numeric);
161	print_ports("dpt", udp->dpts[0], udp->dpts[1],
162		    udp->invflags & XT_UDP_INV_DSTPT,
163		    numeric);
164	if (udp->invflags & ~XT_UDP_INV_MASK)
165		printf("Unknown invflags: 0x%X ",
166		       udp->invflags & ~XT_UDP_INV_MASK);
167}
168
169/* Saves the union ipt_matchinfo in parsable form to stdout. */
170static void save(const void *ip, const struct xt_entry_match *match)
171{
172	const struct xt_udp *udpinfo = (struct xt_udp *)match->data;
173
174	if (udpinfo->spts[0] != 0
175	    || udpinfo->spts[1] != 0xFFFF) {
176		if (udpinfo->invflags & XT_UDP_INV_SRCPT)
177			printf("! ");
178		if (udpinfo->spts[0]
179		    != udpinfo->spts[1])
180			printf("--sport %u:%u ",
181			       udpinfo->spts[0],
182			       udpinfo->spts[1]);
183		else
184			printf("--sport %u ",
185			       udpinfo->spts[0]);
186	}
187
188	if (udpinfo->dpts[0] != 0
189	    || udpinfo->dpts[1] != 0xFFFF) {
190		if (udpinfo->invflags & XT_UDP_INV_DSTPT)
191			printf("! ");
192		if (udpinfo->dpts[0]
193		    != udpinfo->dpts[1])
194			printf("--dport %u:%u ",
195			       udpinfo->dpts[0],
196			       udpinfo->dpts[1]);
197		else
198			printf("--dport %u ",
199			       udpinfo->dpts[0]);
200	}
201}
202
203static
204struct xtables_match udp = {
205	.family		= AF_INET,
206	.name		= "udp",
207	.version	= IPTABLES_VERSION,
208	.size		= XT_ALIGN(sizeof(struct xt_udp)),
209	.userspacesize	= XT_ALIGN(sizeof(struct xt_udp)),
210	.help		= &help,
211	.init		= &init,
212	.parse		= &parse,
213	.print		= &print,
214	.save		= &save,
215	.extra_opts	= opts
216};
217
218static
219struct xtables_match udp6 = {
220	.family		= AF_INET6,
221	.name		= "udp",
222	.version	= IPTABLES_VERSION,
223	.size		= XT_ALIGN(sizeof(struct xt_udp)),
224	.userspacesize	= XT_ALIGN(sizeof(struct xt_udp)),
225	.help		= &help,
226	.init		= &init,
227	.parse		= &parse,
228	.print		= &print,
229	.save		= &save,
230	.extra_opts	= opts
231};
232
233void
234_init(void)
235{
236	xtables_register_match(&udp);
237	xtables_register_match(&udp6);
238}
239