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      1 /* Shared library add-on to iptables for DCCP matching
      2  *
      3  * (C) 2005 by Harald Welte <laforge (at) 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 
     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
     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 
    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 *
    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
    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
    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
    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
    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
    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 
    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 const char *const dccp_pkt_types_xlate[] = {
    281 	[DCCP_PKT_REQUEST]      = "request",
    282 	[DCCP_PKT_RESPONSE]     = "response",
    283 	[DCCP_PKT_DATA]         = "data",
    284 	[DCCP_PKT_ACK]          = "ack",
    285 	[DCCP_PKT_DATAACK]      = "dataack",
    286 	[DCCP_PKT_CLOSEREQ]     = "closereq",
    287 	[DCCP_PKT_CLOSE]        = "close",
    288 	[DCCP_PKT_RESET]        = "reset",
    289 	[DCCP_PKT_SYNC]         = "sync",
    290 	[DCCP_PKT_SYNCACK]      = "syncack",
    291 };
    292 
    293 static int dccp_type_xlate(const struct xt_dccp_info *einfo,
    294 			   struct xt_xlate *xl)
    295 {
    296 	bool have_type = false, set_need = false;
    297 	uint16_t types = einfo->typemask;
    298 
    299 	if (types & (1 << DCCP_PKT_INVALID))
    300 		return 0;
    301 
    302 	xt_xlate_add(xl, " dccp type%s ", einfo->invflags ? " !=" : "");
    303 
    304 	if ((types != 0) && !(types == (types & -types))) {
    305 		xt_xlate_add(xl, "{");
    306 		set_need = true;
    307 	}
    308 
    309 	while (types) {
    310 		unsigned int i;
    311 
    312 		for (i = 0; !(types & (1 << i)); i++);
    313 
    314 		if (have_type)
    315 			xt_xlate_add(xl, ", ");
    316 		else
    317 			have_type = true;
    318 
    319 		xt_xlate_add(xl, "%s", dccp_pkt_types_xlate[i]);
    320 
    321 		types &= ~(1 << i);
    322 	}
    323 
    324 	if (set_need)
    325 		xt_xlate_add(xl, "}");
    326 
    327 	return 1;
    328 }
    329 
    330 static int dccp_xlate(struct xt_xlate *xl,
    331 		      const struct xt_xlate_mt_params *params)
    332 {
    333 	const struct xt_dccp_info *einfo =
    334 		(const struct xt_dccp_info *)params->match->data;
    335 	char *space = "";
    336 	int ret = 1;
    337 
    338 	xt_xlate_add(xl, "dccp ");
    339 
    340 	if (einfo->flags & XT_DCCP_SRC_PORTS) {
    341 		if (einfo->spts[0] != einfo->spts[1])
    342 			xt_xlate_add(xl, "sport%s %u-%u",
    343 				     einfo->invflags & XT_DCCP_SRC_PORTS ? " !=" : "",
    344 				     einfo->spts[0], einfo->spts[1]);
    345 		else
    346 			xt_xlate_add(xl, "sport%s %u",
    347 				     einfo->invflags & XT_DCCP_SRC_PORTS ? " !=" : "",
    348 				     einfo->spts[0]);
    349 		space = " ";
    350 	}
    351 
    352 	if (einfo->flags & XT_DCCP_DEST_PORTS) {
    353 		if (einfo->dpts[0] != einfo->dpts[1])
    354 			xt_xlate_add(xl, "%sdport%s %u-%u", space,
    355 				     einfo->invflags & XT_DCCP_DEST_PORTS ? " !=" : "",
    356 				     einfo->dpts[0], einfo->dpts[1]);
    357 		else
    358 			xt_xlate_add(xl, "%sdport%s %u", space,
    359 				     einfo->invflags & XT_DCCP_DEST_PORTS ? " !=" : "",
    360 				     einfo->dpts[0]);
    361 	}
    362 
    363 	if (einfo->flags & XT_DCCP_TYPE)
    364 		ret = dccp_type_xlate(einfo, xl);
    365 
    366 	if (einfo->flags & XT_DCCP_OPTION)
    367 		ret = 0;
    368 
    369 	return ret;
    370 }
    371 static struct xtables_match dccp_match = {
    372 	.name		= "dccp",
    373 	.family		= NFPROTO_UNSPEC,
    374 	.version	= XTABLES_VERSION,
    375 	.size		= XT_ALIGN(sizeof(struct xt_dccp_info)),
    376 	.userspacesize	= XT_ALIGN(sizeof(struct xt_dccp_info)),
    377 	.help		= dccp_help,
    378 	.print		= dccp_print,
    379 	.save		= dccp_save,
    380 	.x6_parse	= dccp_parse,
    381 	.x6_options	= dccp_opts,
    382 	.xlate		= dccp_xlate,
    383 };
    384 
    385 void _init(void)
    386 {
    387 	xtables_register_match(&dccp_match);
    388 }
    389