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
26 enum {
27 O_SOURCE_PORT = 0,
28 O_DEST_PORT,
29 O_DCCP_TYPES,
30 O_DCCP_OPTION,
31 };
32
dccp_help(void)33 static 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
47 static 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
65 static 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
79 static uint16_t
parse_dccp_types(const char * typestring)80 parse_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
dccp_parse(struct xt_option_call * cb)103 static 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
133 static const char *
port_to_service(int port)134 port_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
144 static void
print_port(uint16_t port,int numeric)145 print_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
155 static void
print_ports(const char * name,uint16_t min,uint16_t max,int invert,int numeric)156 print_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
175 static void
print_types(uint16_t types,int inverted,int numeric)176 print_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
203 static void
print_option(uint8_t option,int invert,int numeric)204 print_option(uint8_t option, int invert, int numeric)
205 {
206 if (option || invert)
207 printf(" option=%s%u", invert ? "!" : "", option);
208 }
209
210 static void
dccp_print(const void * ip,const struct xt_entry_match * match,int numeric)211 dccp_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
dccp_save(const void * ip,const struct xt_entry_match * match)242 static 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
280 static 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
_init(void)293 void _init(void)
294 {
295 xtables_register_match(&dccp_match);
296 }
297