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 int
34service_to_port(const char *name)
35{
36	struct servent *service;
37
38	if ((service = getservbyname(name, "udp")) != NULL)
39		return ntohs((unsigned short) service->s_port);
40
41		return -1;
42}
43
44static u_int16_t
45parse_udp_port(const char *port)
46{
47	unsigned int portnum;
48
49	if (string_to_number(port, 0, 65535, &portnum) != -1 ||
50	    (portnum = service_to_port(port)) != -1)
51		return (u_int16_t)portnum;
52
53		exit_error(PARAMETER_PROBLEM,
54			   "invalid UDP port/service `%s' specified", port);
55	}
56
57static void
58parse_udp_ports(const char *portstring, u_int16_t *ports)
59{
60	char *buffer;
61	char *cp;
62
63	buffer = strdup(portstring);
64	if ((cp = strchr(buffer, ':')) == NULL)
65		ports[0] = ports[1] = parse_udp_port(buffer);
66	else {
67		*cp = '\0';
68		cp++;
69
70		ports[0] = buffer[0] ? parse_udp_port(buffer) : 0;
71		ports[1] = cp[0] ? parse_udp_port(cp) : 0xFFFF;
72
73		if (ports[0] > ports[1])
74			exit_error(PARAMETER_PROBLEM,
75				   "invalid portrange (min > max)");
76	}
77	free(buffer);
78}
79
80/* Initialize the match. */
81static void
82init(struct ipt_entry_match *m, unsigned int *nfcache)
83{
84	struct ipt_udp *udpinfo = (struct ipt_udp *)m->data;
85
86	udpinfo->spts[1] = udpinfo->dpts[1] = 0xFFFF;
87}
88
89#define UDP_SRC_PORTS 0x01
90#define UDP_DST_PORTS 0x02
91
92/* Function which parses command options; returns true if it
93   ate an option */
94static int
95parse(int c, char **argv, int invert, unsigned int *flags,
96      const struct ipt_entry *entry,
97      unsigned int *nfcache,
98      struct ipt_entry_match **match)
99{
100	struct ipt_udp *udpinfo = (struct ipt_udp *)(*match)->data;
101
102	switch (c) {
103	case '1':
104		if (*flags & UDP_SRC_PORTS)
105			exit_error(PARAMETER_PROBLEM,
106				   "Only one `--source-port' allowed");
107		check_inverse(optarg, &invert, &optind, 0);
108		parse_udp_ports(argv[optind-1], udpinfo->spts);
109		if (invert)
110			udpinfo->invflags |= IPT_UDP_INV_SRCPT;
111		*flags |= UDP_SRC_PORTS;
112		*nfcache |= NFC_IP_SRC_PT;
113		break;
114
115	case '2':
116		if (*flags & UDP_DST_PORTS)
117			exit_error(PARAMETER_PROBLEM,
118				   "Only one `--destination-port' allowed");
119		check_inverse(optarg, &invert, &optind, 0);
120		parse_udp_ports(argv[optind-1], udpinfo->dpts);
121		if (invert)
122			udpinfo->invflags |= IPT_UDP_INV_DSTPT;
123		*flags |= UDP_DST_PORTS;
124		*nfcache |= NFC_IP_DST_PT;
125		break;
126
127	default:
128		return 0;
129	}
130
131	return 1;
132}
133
134/* Final check; we don't care. */
135static void
136final_check(unsigned int flags)
137{
138}
139
140static char *
141port_to_service(int port)
142{
143	struct servent *service;
144
145	if ((service = getservbyport(htons(port), "udp")))
146		return service->s_name;
147
148	return NULL;
149}
150
151static void
152print_port(u_int16_t port, int numeric)
153{
154	char *service;
155
156	if (numeric || (service = port_to_service(port)) == NULL)
157		printf("%u", port);
158	else
159		printf("%s", service);
160}
161
162static void
163print_ports(const char *name, u_int16_t min, u_int16_t max,
164	    int invert, int numeric)
165{
166	const char *inv = invert ? "!" : "";
167
168	if (min != 0 || max != 0xFFFF || invert) {
169		printf("%s", name);
170		if (min == max) {
171			printf(":%s", inv);
172			print_port(min, numeric);
173		} else {
174			printf("s:%s", inv);
175			print_port(min, numeric);
176			printf(":");
177			print_port(max, numeric);
178		}
179		printf(" ");
180	}
181}
182
183/* Prints out the union ipt_matchinfo. */
184static void
185print(const struct ipt_ip *ip,
186      const struct ipt_entry_match *match, int numeric)
187{
188	const struct ipt_udp *udp = (struct ipt_udp *)match->data;
189
190	printf("udp ");
191	print_ports("spt", udp->spts[0], udp->spts[1],
192		    udp->invflags & IPT_UDP_INV_SRCPT,
193		    numeric);
194	print_ports("dpt", udp->dpts[0], udp->dpts[1],
195		    udp->invflags & IPT_UDP_INV_DSTPT,
196		    numeric);
197	if (udp->invflags & ~IPT_UDP_INV_MASK)
198		printf("Unknown invflags: 0x%X ",
199		       udp->invflags & ~IPT_UDP_INV_MASK);
200}
201
202/* Saves the union ipt_matchinfo in parsable form to stdout. */
203static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
204{
205	const struct ipt_udp *udpinfo = (struct ipt_udp *)match->data;
206
207	if (udpinfo->spts[0] != 0
208	    || udpinfo->spts[1] != 0xFFFF) {
209		if (udpinfo->invflags & IPT_UDP_INV_SRCPT)
210			printf("! ");
211		if (udpinfo->spts[0]
212		    != udpinfo->spts[1])
213			printf("--sport %u:%u ",
214			       udpinfo->spts[0],
215			       udpinfo->spts[1]);
216		else
217			printf("--sport %u ",
218			       udpinfo->spts[0]);
219	}
220
221	if (udpinfo->dpts[0] != 0
222	    || udpinfo->dpts[1] != 0xFFFF) {
223		if (udpinfo->invflags & IPT_UDP_INV_DSTPT)
224			printf("! ");
225		if (udpinfo->dpts[0]
226		    != udpinfo->dpts[1])
227			printf("--dport %u:%u ",
228			       udpinfo->dpts[0],
229			       udpinfo->dpts[1]);
230		else
231			printf("--dport %u ",
232			       udpinfo->dpts[0]);
233	}
234}
235
236static
237struct iptables_match udp
238= { NULL,
239    "udp",
240    IPTABLES_VERSION,
241    IPT_ALIGN(sizeof(struct ipt_udp)),
242    IPT_ALIGN(sizeof(struct ipt_udp)),
243    &help,
244    &init,
245    &parse,
246    &final_check,
247    &print,
248    &save,
249    opts
250};
251
252void
253_init(void)
254{
255	register_match(&udp);
256}
257