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 <iptables.h>
8#include <linux/netfilter_ipv4/ip_tables.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 struct option opts[] = {
26	{ "source-port", 1, 0, '1' },
27	{ "sport", 1, 0, '1' }, /* synonym */
28	{ "destination-port", 1, 0, '2' },
29	{ "dport", 1, 0, '2' }, /* synonym */
30	{0}
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 ipt_entry_match *m, unsigned int *nfcache)
59{
60	struct ipt_udp *udpinfo = (struct ipt_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 struct ipt_entry *entry,
73      unsigned int *nfcache,
74      struct ipt_entry_match **match)
75{
76	struct ipt_udp *udpinfo = (struct ipt_udp *)(*match)->data;
77
78	switch (c) {
79	case '1':
80		if (*flags & UDP_SRC_PORTS)
81			exit_error(PARAMETER_PROBLEM,
82				   "Only one `--source-port' allowed");
83		check_inverse(optarg, &invert, &optind, 0);
84		parse_udp_ports(argv[optind-1], udpinfo->spts);
85		if (invert)
86			udpinfo->invflags |= IPT_UDP_INV_SRCPT;
87		*flags |= UDP_SRC_PORTS;
88		break;
89
90	case '2':
91		if (*flags & UDP_DST_PORTS)
92			exit_error(PARAMETER_PROBLEM,
93				   "Only one `--destination-port' allowed");
94		check_inverse(optarg, &invert, &optind, 0);
95		parse_udp_ports(argv[optind-1], udpinfo->dpts);
96		if (invert)
97			udpinfo->invflags |= IPT_UDP_INV_DSTPT;
98		*flags |= UDP_DST_PORTS;
99		break;
100
101	default:
102		return 0;
103	}
104
105	return 1;
106}
107
108/* Final check; we don't care. */
109static void
110final_check(unsigned int flags)
111{
112}
113
114static char *
115port_to_service(int port)
116{
117	struct servent *service;
118
119	if ((service = getservbyport(htons(port), "udp")))
120		return service->s_name;
121
122	return NULL;
123}
124
125static void
126print_port(u_int16_t port, int numeric)
127{
128	char *service;
129
130	if (numeric || (service = port_to_service(port)) == NULL)
131		printf("%u", port);
132	else
133		printf("%s", service);
134}
135
136static void
137print_ports(const char *name, u_int16_t min, u_int16_t max,
138	    int invert, int numeric)
139{
140	const char *inv = invert ? "!" : "";
141
142	if (min != 0 || max != 0xFFFF || invert) {
143		printf("%s", name);
144		if (min == max) {
145			printf(":%s", inv);
146			print_port(min, numeric);
147		} else {
148			printf("s:%s", inv);
149			print_port(min, numeric);
150			printf(":");
151			print_port(max, numeric);
152		}
153		printf(" ");
154	}
155}
156
157/* Prints out the union ipt_matchinfo. */
158static void
159print(const struct ipt_ip *ip,
160      const struct ipt_entry_match *match, int numeric)
161{
162	const struct ipt_udp *udp = (struct ipt_udp *)match->data;
163
164	printf("udp ");
165	print_ports("spt", udp->spts[0], udp->spts[1],
166		    udp->invflags & IPT_UDP_INV_SRCPT,
167		    numeric);
168	print_ports("dpt", udp->dpts[0], udp->dpts[1],
169		    udp->invflags & IPT_UDP_INV_DSTPT,
170		    numeric);
171	if (udp->invflags & ~IPT_UDP_INV_MASK)
172		printf("Unknown invflags: 0x%X ",
173		       udp->invflags & ~IPT_UDP_INV_MASK);
174}
175
176/* Saves the union ipt_matchinfo in parsable form to stdout. */
177static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
178{
179	const struct ipt_udp *udpinfo = (struct ipt_udp *)match->data;
180
181	if (udpinfo->spts[0] != 0
182	    || udpinfo->spts[1] != 0xFFFF) {
183		if (udpinfo->invflags & IPT_UDP_INV_SRCPT)
184			printf("! ");
185		if (udpinfo->spts[0]
186		    != udpinfo->spts[1])
187			printf("--sport %u:%u ",
188			       udpinfo->spts[0],
189			       udpinfo->spts[1]);
190		else
191			printf("--sport %u ",
192			       udpinfo->spts[0]);
193	}
194
195	if (udpinfo->dpts[0] != 0
196	    || udpinfo->dpts[1] != 0xFFFF) {
197		if (udpinfo->invflags & IPT_UDP_INV_DSTPT)
198			printf("! ");
199		if (udpinfo->dpts[0]
200		    != udpinfo->dpts[1])
201			printf("--dport %u:%u ",
202			       udpinfo->dpts[0],
203			       udpinfo->dpts[1]);
204		else
205			printf("--dport %u ",
206			       udpinfo->dpts[0]);
207	}
208}
209
210static
211struct iptables_match udp = {
212	.next		= NULL,
213	.name		= "udp",
214	.version	= IPTABLES_VERSION,
215	.size		= IPT_ALIGN(sizeof(struct ipt_udp)),
216	.userspacesize	= IPT_ALIGN(sizeof(struct ipt_udp)),
217	.help		= &help,
218	.init		= &init,
219	.parse		= &parse,
220	.final_check	= &final_check,
221	.print		= &print,
222	.save		= &save,
223	.extra_opts	= opts
224};
225
226void
227_init(void)
228{
229	register_match(&udp);
230}
231