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 <stdint.h>
9#include <stdio.h>
10#include <string.h>
11#include <stdlib.h>
12#include <netdb.h>
13#include <arpa/inet.h>
14#include <xtables.h>
15#include <linux/dccp.h>
16#include <linux/netfilter/x_tables.h>
17#include <linux/netfilter/xt_dccp.h>
18
19#if 0
20#define DEBUGP(format, first...) printf(format, ##first)
21#define static
22#else
23#define DEBUGP(format, fist...)
24#endif
25
26enum {
27	O_SOURCE_PORT = 0,
28	O_DEST_PORT,
29	O_DCCP_TYPES,
30	O_DCCP_OPTION,
31};
32
33static void dccp_help(void)
34{
35	printf(
36"dccp match options\n"
37"[!] --source-port port[:port]                          match source port(s)\n"
38" --sport ...\n"
39"[!] --destination-port port[:port]                     match destination port(s)\n"
40" --dport ...\n"
41"[!] --dccp-types type[,...]                            match when packet is one of the given types\n"
42"[!] --dccp-option option                               match if option (by number!) is set\n"
43);
44}
45
46#define s struct xt_dccp_info
47static const struct xt_option_entry dccp_opts[] = {
48	{.name = "source-port", .id = O_SOURCE_PORT, .type = XTTYPE_PORTRC,
49	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, spts)},
50	{.name = "sport", .id = O_SOURCE_PORT, .type = XTTYPE_PORTRC,
51	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, spts)},
52	{.name = "destination-port", .id = O_DEST_PORT, .type = XTTYPE_PORTRC,
53	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, dpts)},
54	{.name = "dport", .id = O_DEST_PORT, .type = XTTYPE_PORTRC,
55	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, dpts)},
56	{.name = "dccp-types", .id = O_DCCP_TYPES, .type = XTTYPE_STRING,
57	 .flags = XTOPT_INVERT},
58	{.name = "dccp-option", .id = O_DCCP_OPTION, .type = XTTYPE_UINT8,
59	 .min = 1, .max = UINT8_MAX, .flags = XTOPT_INVERT | XTOPT_PUT,
60	 XTOPT_POINTER(s, option)},
61	XTOPT_TABLEEND,
62};
63#undef s
64
65static const char *const dccp_pkt_types[] = {
66	[DCCP_PKT_REQUEST] 	= "REQUEST",
67	[DCCP_PKT_RESPONSE]	= "RESPONSE",
68	[DCCP_PKT_DATA]		= "DATA",
69	[DCCP_PKT_ACK]		= "ACK",
70	[DCCP_PKT_DATAACK]	= "DATAACK",
71	[DCCP_PKT_CLOSEREQ]	= "CLOSEREQ",
72	[DCCP_PKT_CLOSE]	= "CLOSE",
73	[DCCP_PKT_RESET]	= "RESET",
74	[DCCP_PKT_SYNC]		= "SYNC",
75	[DCCP_PKT_SYNCACK]	= "SYNCACK",
76	[DCCP_PKT_INVALID]	= "INVALID",
77};
78
79static uint16_t
80parse_dccp_types(const char *typestring)
81{
82	uint16_t typemask = 0;
83	char *ptr, *buffer;
84
85	buffer = strdup(typestring);
86
87	for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ",")) {
88		unsigned int i;
89		for (i = 0; i < ARRAY_SIZE(dccp_pkt_types); ++i)
90			if (!strcasecmp(dccp_pkt_types[i], ptr)) {
91				typemask |= (1 << i);
92				break;
93			}
94		if (i == ARRAY_SIZE(dccp_pkt_types))
95			xtables_error(PARAMETER_PROBLEM,
96				   "Unknown DCCP type `%s'", ptr);
97	}
98
99	free(buffer);
100	return typemask;
101}
102
103static void dccp_parse(struct xt_option_call *cb)
104{
105	struct xt_dccp_info *einfo = cb->data;
106
107	xtables_option_parse(cb);
108	switch (cb->entry->id) {
109	case O_SOURCE_PORT:
110		einfo->flags |= XT_DCCP_SRC_PORTS;
111		if (cb->invert)
112			einfo->invflags |= XT_DCCP_SRC_PORTS;
113		break;
114	case O_DEST_PORT:
115		einfo->flags |= XT_DCCP_DEST_PORTS;
116		if (cb->invert)
117			einfo->invflags |= XT_DCCP_DEST_PORTS;
118		break;
119	case O_DCCP_TYPES:
120		einfo->flags |= XT_DCCP_TYPE;
121		einfo->typemask = parse_dccp_types(cb->arg);
122		if (cb->invert)
123			einfo->invflags |= XT_DCCP_TYPE;
124		break;
125	case O_DCCP_OPTION:
126		einfo->flags |= XT_DCCP_OPTION;
127		if (cb->invert)
128			einfo->invflags |= XT_DCCP_OPTION;
129		break;
130	}
131}
132
133static const char *
134port_to_service(int port)
135{
136	const struct servent *service;
137
138	if ((service = getservbyport(htons(port), "dccp")))
139		return service->s_name;
140
141	return NULL;
142}
143
144static void
145print_port(uint16_t port, int numeric)
146{
147	const char *service;
148
149	if (numeric || (service = port_to_service(port)) == NULL)
150		printf("%u", port);
151	else
152		printf("%s", service);
153}
154
155static void
156print_ports(const char *name, uint16_t min, uint16_t max,
157	    int invert, int numeric)
158{
159	const char *inv = invert ? "!" : "";
160
161	if (min != 0 || max != 0xFFFF || invert) {
162		printf(" %s", name);
163		if (min == max) {
164			printf(":%s", inv);
165			print_port(min, numeric);
166		} else {
167			printf("s:%s", inv);
168			print_port(min, numeric);
169			printf(":");
170			print_port(max, numeric);
171		}
172	}
173}
174
175static void
176print_types(uint16_t types, int inverted, int numeric)
177{
178	int have_type = 0;
179
180	if (inverted)
181		printf(" !");
182
183	printf(" ");
184	while (types) {
185		unsigned int i;
186
187		for (i = 0; !(types & (1 << i)); i++);
188
189		if (have_type)
190			printf(",");
191		else
192			have_type = 1;
193
194		if (numeric)
195			printf("%u", i);
196		else
197			printf("%s", dccp_pkt_types[i]);
198
199		types &= ~(1 << i);
200	}
201}
202
203static void
204print_option(uint8_t option, int invert, int numeric)
205{
206	if (option || invert)
207		printf(" option=%s%u", invert ? "!" : "", option);
208}
209
210static void
211dccp_print(const void *ip, const struct xt_entry_match *match, int numeric)
212{
213	const struct xt_dccp_info *einfo =
214		(const struct xt_dccp_info *)match->data;
215
216	printf(" dccp");
217
218	if (einfo->flags & XT_DCCP_SRC_PORTS) {
219		print_ports("spt", einfo->spts[0], einfo->spts[1],
220			einfo->invflags & XT_DCCP_SRC_PORTS,
221			numeric);
222	}
223
224	if (einfo->flags & XT_DCCP_DEST_PORTS) {
225		print_ports("dpt", einfo->dpts[0], einfo->dpts[1],
226			einfo->invflags & XT_DCCP_DEST_PORTS,
227			numeric);
228	}
229
230	if (einfo->flags & XT_DCCP_TYPE) {
231		print_types(einfo->typemask,
232			   einfo->invflags & XT_DCCP_TYPE,
233			   numeric);
234	}
235
236	if (einfo->flags & XT_DCCP_OPTION) {
237		print_option(einfo->option,
238			     einfo->invflags & XT_DCCP_OPTION, numeric);
239	}
240}
241
242static void dccp_save(const void *ip, const struct xt_entry_match *match)
243{
244	const struct xt_dccp_info *einfo =
245		(const struct xt_dccp_info *)match->data;
246
247	if (einfo->flags & XT_DCCP_SRC_PORTS) {
248		if (einfo->invflags & XT_DCCP_SRC_PORTS)
249			printf(" !");
250		if (einfo->spts[0] != einfo->spts[1])
251			printf(" --sport %u:%u",
252			       einfo->spts[0], einfo->spts[1]);
253		else
254			printf(" --sport %u", einfo->spts[0]);
255	}
256
257	if (einfo->flags & XT_DCCP_DEST_PORTS) {
258		if (einfo->invflags & XT_DCCP_DEST_PORTS)
259			printf(" !");
260		if (einfo->dpts[0] != einfo->dpts[1])
261			printf(" --dport %u:%u",
262			       einfo->dpts[0], einfo->dpts[1]);
263		else
264			printf(" --dport %u", einfo->dpts[0]);
265	}
266
267	if (einfo->flags & XT_DCCP_TYPE) {
268		printf("%s --dccp-types",
269		       einfo->invflags & XT_DCCP_TYPE ? " !" : "");
270		print_types(einfo->typemask, false, 0);
271	}
272
273	if (einfo->flags & XT_DCCP_OPTION) {
274		printf("%s --dccp-option %u",
275			einfo->invflags & XT_DCCP_OPTION ? " !" : "",
276			einfo->option);
277	}
278}
279
280static struct xtables_match dccp_match = {
281	.name		= "dccp",
282	.family		= NFPROTO_UNSPEC,
283	.version	= XTABLES_VERSION,
284	.size		= XT_ALIGN(sizeof(struct xt_dccp_info)),
285	.userspacesize	= XT_ALIGN(sizeof(struct xt_dccp_info)),
286	.help		= dccp_help,
287	.print		= dccp_print,
288	.save		= dccp_save,
289	.x6_parse	= dccp_parse,
290	.x6_options	= dccp_opts,
291};
292
293void _init(void)
294{
295	xtables_register_match(&dccp_match);
296}
297