libxt_dccp.c revision 73866357e4a7a0fdc1b293bf8863fee2bd56da9e 
1/* Shared library add-on to iptables for DCCP matching
2 *
3 * (C) 2005 by Harald Welte <laforge@netfilter.org>
4 *
5 * This program is distributed under the terms of GNU GPL v2, 1991
6 *
7 */
8#include <stdbool.h>
9#include <stdio.h>
10#include <string.h>
11#include <stdlib.h>
12#include <getopt.h>
13#include <netdb.h>
14#include <ctype.h>
15
16#include <netinet/in.h>
17#include <xtables.h>
18#include <linux/dccp.h>
19#include <linux/netfilter/x_tables.h>
20#include <linux/netfilter/xt_dccp.h>
21
22#if 0
23#define DEBUGP(format, first...) printf(format, ##first)
24#define static
25#else
26#define DEBUGP(format, fist...)
27#endif
28
29static void dccp_init(struct xt_entry_match *m)
30{
31	struct xt_dccp_info *einfo = (struct xt_dccp_info *)m->data;
32
33	memset(einfo, 0, sizeof(struct xt_dccp_info));
34}
35
36static void dccp_help(void)
37{
38	printf(
39"dccp match options\n"
40"[!] --source-port port[:port]                          match source port(s)\n"
41" --sport ...\n"
42"[!] --destination-port port[:port]                     match destination port(s)\n"
43" --dport ...\n");
44}
45
46static const struct option dccp_opts[] = {
47	{.name = "source-port",      .has_arg = true, .val = '1'},
48	{.name = "sport",            .has_arg = true, .val = '1'},
49	{.name = "destination-port", .has_arg = true, .val = '2'},
50	{.name = "dport",            .has_arg = true, .val = '2'},
51	{.name = "dccp-types",       .has_arg = true, .val = '3'},
52	{.name = "dccp-option",      .has_arg = true, .val = '4'},
53	XT_GETOPT_TABLEEND,
54};
55
56static void
57parse_dccp_ports(const char *portstring,
58		 uint16_t *ports)
59{
60	char *buffer;
61	char *cp;
62
63	buffer = strdup(portstring);
64	DEBUGP("%s\n", portstring);
65	if ((cp = strchr(buffer, ':')) == NULL) {
66		ports[0] = ports[1] = xtables_parse_port(buffer, "dccp");
67	}
68	else {
69		*cp = '\0';
70		cp++;
71
72		ports[0] = buffer[0] ? xtables_parse_port(buffer, "dccp") : 0;
73		ports[1] = cp[0] ? xtables_parse_port(cp, "dccp") : 0xFFFF;
74
75		if (ports[0] > ports[1])
76			xtables_error(PARAMETER_PROBLEM,
77				   "invalid portrange (min > max)");
78	}
79	free(buffer);
80}
81
82static const char *const dccp_pkt_types[] = {
83	[DCCP_PKT_REQUEST] 	= "REQUEST",
84	[DCCP_PKT_RESPONSE]	= "RESPONSE",
85	[DCCP_PKT_DATA]		= "DATA",
86	[DCCP_PKT_ACK]		= "ACK",
87	[DCCP_PKT_DATAACK]	= "DATAACK",
88	[DCCP_PKT_CLOSEREQ]	= "CLOSEREQ",
89	[DCCP_PKT_CLOSE]	= "CLOSE",
90	[DCCP_PKT_RESET]	= "RESET",
91	[DCCP_PKT_SYNC]		= "SYNC",
92	[DCCP_PKT_SYNCACK]	= "SYNCACK",
93	[DCCP_PKT_INVALID]	= "INVALID",
94};
95
96static uint16_t
97parse_dccp_types(const char *typestring)
98{
99	uint16_t typemask = 0;
100	char *ptr, *buffer;
101
102	buffer = strdup(typestring);
103
104	for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ",")) {
105		unsigned int i;
106		for (i = 0; i < ARRAY_SIZE(dccp_pkt_types); ++i)
107			if (!strcasecmp(dccp_pkt_types[i], ptr)) {
108				typemask |= (1 << i);
109				break;
110			}
111		if (i == ARRAY_SIZE(dccp_pkt_types))
112			xtables_error(PARAMETER_PROBLEM,
113				   "Unknown DCCP type `%s'", ptr);
114	}
115
116	free(buffer);
117	return typemask;
118}
119
120static uint8_t parse_dccp_option(char *optstring)
121{
122	unsigned int ret;
123
124	if (!xtables_strtoui(optstring, NULL, &ret, 1, UINT8_MAX))
125		xtables_error(PARAMETER_PROBLEM, "Bad DCCP option \"%s\"",
126			   optstring);
127
128	return ret;
129}
130
131static int
132dccp_parse(int c, char **argv, int invert, unsigned int *flags,
133           const void *entry, struct xt_entry_match **match)
134{
135	struct xt_dccp_info *einfo
136		= (struct xt_dccp_info *)(*match)->data;
137
138	switch (c) {
139	case '1':
140		if (*flags & XT_DCCP_SRC_PORTS)
141			xtables_error(PARAMETER_PROBLEM,
142			           "Only one `--source-port' allowed");
143		einfo->flags |= XT_DCCP_SRC_PORTS;
144		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
145		parse_dccp_ports(optarg, einfo->spts);
146		if (invert)
147			einfo->invflags |= XT_DCCP_SRC_PORTS;
148		*flags |= XT_DCCP_SRC_PORTS;
149		break;
150
151	case '2':
152		if (*flags & XT_DCCP_DEST_PORTS)
153			xtables_error(PARAMETER_PROBLEM,
154				   "Only one `--destination-port' allowed");
155		einfo->flags |= XT_DCCP_DEST_PORTS;
156		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
157		parse_dccp_ports(optarg, einfo->dpts);
158		if (invert)
159			einfo->invflags |= XT_DCCP_DEST_PORTS;
160		*flags |= XT_DCCP_DEST_PORTS;
161		break;
162
163	case '3':
164		if (*flags & XT_DCCP_TYPE)
165			xtables_error(PARAMETER_PROBLEM,
166				   "Only one `--dccp-types' allowed");
167		einfo->flags |= XT_DCCP_TYPE;
168		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
169		einfo->typemask = parse_dccp_types(optarg);
170		if (invert)
171			einfo->invflags |= XT_DCCP_TYPE;
172		*flags |= XT_DCCP_TYPE;
173		break;
174
175	case '4':
176		if (*flags & XT_DCCP_OPTION)
177			xtables_error(PARAMETER_PROBLEM,
178				   "Only one `--dccp-option' allowed");
179		einfo->flags |= XT_DCCP_OPTION;
180		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
181		einfo->option = parse_dccp_option(optarg);
182		if (invert)
183			einfo->invflags |= XT_DCCP_OPTION;
184		*flags |= XT_DCCP_OPTION;
185		break;
186	}
187	return 1;
188}
189
190static char *
191port_to_service(int port)
192{
193	struct servent *service;
194
195	if ((service = getservbyport(htons(port), "dccp")))
196		return service->s_name;
197
198	return NULL;
199}
200
201static void
202print_port(uint16_t port, int numeric)
203{
204	char *service;
205
206	if (numeric || (service = port_to_service(port)) == NULL)
207		printf("%u", port);
208	else
209		printf("%s", service);
210}
211
212static void
213print_ports(const char *name, uint16_t min, uint16_t max,
214	    int invert, int numeric)
215{
216	const char *inv = invert ? "!" : "";
217
218	if (min != 0 || max != 0xFFFF || invert) {
219		printf(" %s", name);
220		if (min == max) {
221			printf(":%s", inv);
222			print_port(min, numeric);
223		} else {
224			printf("s:%s", inv);
225			print_port(min, numeric);
226			printf(":");
227			print_port(max, numeric);
228		}
229	}
230}
231
232static void
233print_types(uint16_t types, int inverted, int numeric)
234{
235	int have_type = 0;
236
237	if (inverted)
238		printf(" !");
239
240	printf(" ");
241	while (types) {
242		unsigned int i;
243
244		for (i = 0; !(types & (1 << i)); i++);
245
246		if (have_type)
247			printf(",");
248		else
249			have_type = 1;
250
251		if (numeric)
252			printf("%u", i);
253		else
254			printf("%s", dccp_pkt_types[i]);
255
256		types &= ~(1 << i);
257	}
258}
259
260static void
261print_option(uint8_t option, int invert, int numeric)
262{
263	if (option || invert)
264		printf(" option=%s%u", invert ? "!" : "", option);
265}
266
267static void
268dccp_print(const void *ip, const struct xt_entry_match *match, int numeric)
269{
270	const struct xt_dccp_info *einfo =
271		(const struct xt_dccp_info *)match->data;
272
273	printf(" dccp");
274
275	if (einfo->flags & XT_DCCP_SRC_PORTS) {
276		print_ports("spt", einfo->spts[0], einfo->spts[1],
277			einfo->invflags & XT_DCCP_SRC_PORTS,
278			numeric);
279	}
280
281	if (einfo->flags & XT_DCCP_DEST_PORTS) {
282		print_ports("dpt", einfo->dpts[0], einfo->dpts[1],
283			einfo->invflags & XT_DCCP_DEST_PORTS,
284			numeric);
285	}
286
287	if (einfo->flags & XT_DCCP_TYPE) {
288		print_types(einfo->typemask,
289			   einfo->invflags & XT_DCCP_TYPE,
290			   numeric);
291	}
292
293	if (einfo->flags & XT_DCCP_OPTION) {
294		print_option(einfo->option,
295			     einfo->invflags & XT_DCCP_OPTION, numeric);
296	}
297}
298
299static void dccp_save(const void *ip, const struct xt_entry_match *match)
300{
301	const struct xt_dccp_info *einfo =
302		(const struct xt_dccp_info *)match->data;
303
304	if (einfo->flags & XT_DCCP_SRC_PORTS) {
305		if (einfo->invflags & XT_DCCP_SRC_PORTS)
306			printf(" !");
307		if (einfo->spts[0] != einfo->spts[1])
308			printf(" --sport %u:%u",
309			       einfo->spts[0], einfo->spts[1]);
310		else
311			printf(" --sport %u", einfo->spts[0]);
312	}
313
314	if (einfo->flags & XT_DCCP_DEST_PORTS) {
315		if (einfo->invflags & XT_DCCP_DEST_PORTS)
316			printf(" !");
317		if (einfo->dpts[0] != einfo->dpts[1])
318			printf(" --dport %u:%u",
319			       einfo->dpts[0], einfo->dpts[1]);
320		else
321			printf(" --dport %u", einfo->dpts[0]);
322	}
323
324	if (einfo->flags & XT_DCCP_TYPE) {
325		printf(" --dccp-type");
326		print_types(einfo->typemask, einfo->invflags & XT_DCCP_TYPE,0);
327	}
328
329	if (einfo->flags & XT_DCCP_OPTION) {
330		printf(" --dccp-option %s%u",
331			einfo->typemask & XT_DCCP_OPTION ? "! " : "",
332			einfo->option);
333	}
334}
335
336static struct xtables_match dccp_match = {
337	.name		= "dccp",
338	.family		= NFPROTO_UNSPEC,
339	.version	= XTABLES_VERSION,
340	.size		= XT_ALIGN(sizeof(struct xt_dccp_info)),
341	.userspacesize	= XT_ALIGN(sizeof(struct xt_dccp_info)),
342	.help		= dccp_help,
343	.init		= dccp_init,
344	.parse		= dccp_parse,
345	.print		= dccp_print,
346	.save		= dccp_save,
347	.extra_opts	= dccp_opts,
348};
349
350void _init(void)
351{
352	xtables_register_match(&dccp_match);
353}
354