1 /*
2  * edns-subnet/subnetmod.c - edns subnet module. Must be called before validator
3  * and iterator.
4  *
5  * Copyright (c) 2013, NLnet Labs. All rights reserved.
6  *
7  * This software is open source.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * Redistributions of source code must retain the above copyright notice,
14  * this list of conditions and the following disclaimer.
15  *
16  * Redistributions in binary form must reproduce the above copyright notice,
17  * this list of conditions and the following disclaimer in the documentation
18  * and/or other materials provided with the distribution.
19  *
20  * Neither the name of the NLNET LABS nor the names of its contributors may
21  * be used to endorse or promote products derived from this software without
22  * specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
25  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
26  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
27  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
28  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
30  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
31  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
32  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
33  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
34  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35  */
36  /**
37  * \file
38  * subnet module for unbound.
39  */
40 
41 #include "config.h"
42 
43 #ifdef CLIENT_SUBNET /* keeps splint happy */
44 
45 #include "edns-subnet/subnetmod.h"
46 #include "edns-subnet/edns-subnet.h"
47 #include "edns-subnet/addrtree.h"
48 #include "edns-subnet/subnet-whitelist.h"
49 
50 #include "services/mesh.h"
51 #include "services/cache/dns.h"
52 #include "util/module.h"
53 #include "util/regional.h"
54 #include "util/storage/slabhash.h"
55 #include "util/config_file.h"
56 #include "util/data/msgreply.h"
57 #include "sldns/sbuffer.h"
58 #include "iterator/iter_utils.h"
59 
60 /** externally called */
61 void
62 subnet_data_delete(void *d, void *ATTR_UNUSED(arg))
63 {
64 	struct subnet_msg_cache_data *r;
65 	r = (struct subnet_msg_cache_data*)d;
66 	addrtree_delete(r->tree4);
67 	addrtree_delete(r->tree6);
68 	free(r);
69 }
70 
71 /** externally called */
72 size_t
73 msg_cache_sizefunc(void *k, void *d)
74 {
75 	struct msgreply_entry *q = (struct msgreply_entry*)k;
76 	struct subnet_msg_cache_data *r = (struct subnet_msg_cache_data*)d;
77 	size_t s = sizeof(struct msgreply_entry)
78 		+ sizeof(struct subnet_msg_cache_data)
79 		+ q->key.qname_len + lock_get_mem(&q->entry.lock);
80 	s += addrtree_size(r->tree4);
81 	s += addrtree_size(r->tree6);
82 	return s;
83 }
84 
85 /** new query for ecs module */
86 static int
87 subnet_new_qstate(struct module_qstate *qstate, int id)
88 {
89 	struct subnet_qstate *sq = (struct subnet_qstate*)regional_alloc(
90 		qstate->region, sizeof(struct subnet_qstate));
91 	if(!sq)
92 		return 0;
93 	qstate->minfo[id] = sq;
94 	memset(sq, 0, sizeof(*sq));
95 	sq->started_no_cache_store = qstate->no_cache_store;
96 	return 1;
97 }
98 
99 /** Add ecs struct to edns list, after parsing it to wire format. */
100 static void
101 ecs_opt_list_append(struct ecs_data* ecs, struct edns_option** list,
102 	struct module_qstate *qstate)
103 {
104 	size_t sn_octs, sn_octs_remainder;
105 	sldns_buffer* buf = qstate->env->scratch_buffer;
106 
107 	if(ecs->subnet_validdata) {
108 		log_assert(ecs->subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP4 ||
109 			ecs->subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP6);
110 		log_assert(ecs->subnet_addr_fam != EDNSSUBNET_ADDRFAM_IP4 ||
111 			ecs->subnet_source_mask <=  INET_SIZE*8);
112 		log_assert(ecs->subnet_addr_fam != EDNSSUBNET_ADDRFAM_IP6 ||
113 			ecs->subnet_source_mask <= INET6_SIZE*8);
114 
115 		sn_octs = ecs->subnet_source_mask / 8;
116 		sn_octs_remainder =
117 			(size_t)((ecs->subnet_source_mask % 8)>0?1:0);
118 
119 		log_assert(sn_octs + sn_octs_remainder <= INET6_SIZE);
120 
121 		sldns_buffer_clear(buf);
122 		sldns_buffer_write_u16(buf, ecs->subnet_addr_fam);
123 		sldns_buffer_write_u8(buf, ecs->subnet_source_mask);
124 		sldns_buffer_write_u8(buf, ecs->subnet_scope_mask);
125 		sldns_buffer_write(buf, ecs->subnet_addr, sn_octs);
126 		if(sn_octs_remainder)
127 			sldns_buffer_write_u8(buf, ecs->subnet_addr[sn_octs] &
128 				~(0xFF >> (ecs->subnet_source_mask % 8)));
129 		sldns_buffer_flip(buf);
130 
131 		edns_opt_list_append(list,
132 				qstate->env->cfg->client_subnet_opcode,
133 				sn_octs + sn_octs_remainder + 4,
134 				sldns_buffer_begin(buf), qstate->region);
135 	}
136 }
137 
138 int ecs_whitelist_check(struct query_info* qinfo,
139 	uint16_t ATTR_UNUSED(flags), struct module_qstate* qstate,
140 	struct sockaddr_storage* addr, socklen_t addrlen,
141 	uint8_t* ATTR_UNUSED(zone), size_t ATTR_UNUSED(zonelen),
142 	struct regional* ATTR_UNUSED(region), int id, void* ATTR_UNUSED(cbargs))
143 {
144 	struct subnet_qstate *sq;
145 	struct subnet_env *sn_env;
146 
147 	if(!(sq=(struct subnet_qstate*)qstate->minfo[id]))
148 		return 1;
149 	sn_env = (struct subnet_env*)qstate->env->modinfo[id];
150 
151 	/* Cache by default, might be disabled after parsing EDNS option
152 	 * received from nameserver. */
153 	if(!iter_stub_fwd_no_cache(qstate, &qstate->qinfo)) {
154 		qstate->no_cache_store = 0;
155 	}
156 
157 	if(sq->ecs_server_out.subnet_validdata && ((sq->subnet_downstream &&
158 		qstate->env->cfg->client_subnet_always_forward) ||
159 		ecs_is_whitelisted(sn_env->whitelist,
160 		addr, addrlen, qinfo->qname, qinfo->qname_len,
161 		qinfo->qclass))) {
162 		/* Address on whitelist or client query contains ECS option, we
163 		 * want to sent out ECS. Only add option if it is not already
164 		 * set. */
165 		if(!(sq->subnet_sent)) {
166 			ecs_opt_list_append(&sq->ecs_server_out,
167 				&qstate->edns_opts_back_out, qstate);
168 			sq->subnet_sent = 1;
169 		}
170 	}
171 	else if(sq->subnet_sent) {
172 		/* Outgoing ECS option is set, but we don't want to sent it to
173 		 * this address, remove option. */
174 		edns_opt_list_remove(&qstate->edns_opts_back_out,
175 			qstate->env->cfg->client_subnet_opcode);
176 		sq->subnet_sent = 0;
177 	}
178 	return 1;
179 }
180 
181 
182 void
183 subnet_markdel(void* key)
184 {
185 	struct msgreply_entry *e = (struct msgreply_entry*)key;
186 	e->key.qtype = 0;
187 	e->key.qclass = 0;
188 }
189 
190 int
191 subnetmod_init(struct module_env *env, int id)
192 {
193 	struct subnet_env *sn_env = (struct subnet_env*)calloc(1,
194 		sizeof(struct subnet_env));
195 	if(!sn_env) {
196 		log_err("malloc failure");
197 		return 0;
198 	}
199 	alloc_init(&sn_env->alloc, NULL, 0);
200 	env->modinfo[id] = (void*)sn_env;
201 	/* Copy msg_cache settings */
202 	sn_env->subnet_msg_cache = slabhash_create(env->cfg->msg_cache_slabs,
203 		HASH_DEFAULT_STARTARRAY, env->cfg->msg_cache_size,
204 		msg_cache_sizefunc, query_info_compare, query_entry_delete,
205 		subnet_data_delete, NULL);
206 	slabhash_setmarkdel(sn_env->subnet_msg_cache, &subnet_markdel);
207 	if(!sn_env->subnet_msg_cache) {
208 		log_err("subnet: could not create cache");
209 		free(sn_env);
210 		env->modinfo[id] = NULL;
211 		return 0;
212 	}
213 	/* whitelist for edns subnet capable servers */
214 	sn_env->whitelist = ecs_whitelist_create();
215 	if(!sn_env->whitelist ||
216 		!ecs_whitelist_apply_cfg(sn_env->whitelist, env->cfg)) {
217 		log_err("subnet: could not create ECS whitelist");
218 		slabhash_delete(sn_env->subnet_msg_cache);
219 		free(sn_env);
220 		env->modinfo[id] = NULL;
221 		return 0;
222 	}
223 
224 	verbose(VERB_QUERY, "subnet: option registered (%d)",
225 		env->cfg->client_subnet_opcode);
226 	/* Create new mesh state for all queries. */
227 	env->unique_mesh = 1;
228 	if(!edns_register_option(env->cfg->client_subnet_opcode,
229 		env->cfg->client_subnet_always_forward /* bypass cache */,
230 		0 /* no aggregation */, env)) {
231 		log_err("subnet: could not register opcode");
232 		ecs_whitelist_delete(sn_env->whitelist);
233 		slabhash_delete(sn_env->subnet_msg_cache);
234 		free(sn_env);
235 		env->modinfo[id] = NULL;
236 		return 0;
237 	}
238 	inplace_cb_register((void*)ecs_whitelist_check, inplace_cb_query, NULL,
239 		env, id);
240 	inplace_cb_register((void*)ecs_edns_back_parsed,
241 		inplace_cb_edns_back_parsed, NULL, env, id);
242 	inplace_cb_register((void*)ecs_query_response,
243 		inplace_cb_query_response, NULL, env, id);
244 	lock_rw_init(&sn_env->biglock);
245 	return 1;
246 }
247 
248 void
249 subnetmod_deinit(struct module_env *env, int id)
250 {
251 	struct subnet_env *sn_env;
252 	if(!env || !env->modinfo[id])
253 		return;
254 	sn_env = (struct subnet_env*)env->modinfo[id];
255 	lock_rw_destroy(&sn_env->biglock);
256 	inplace_cb_delete(env, inplace_cb_edns_back_parsed, id);
257 	inplace_cb_delete(env, inplace_cb_query, id);
258 	inplace_cb_delete(env, inplace_cb_query_response, id);
259 	ecs_whitelist_delete(sn_env->whitelist);
260 	slabhash_delete(sn_env->subnet_msg_cache);
261 	alloc_clear(&sn_env->alloc);
262 	free(sn_env);
263 	env->modinfo[id] = NULL;
264 }
265 
266 /** Tells client that upstream has no/improper support */
267 static void
268 cp_edns_bad_response(struct ecs_data *target, struct ecs_data *source)
269 {
270 	target->subnet_scope_mask  = 0;
271 	target->subnet_source_mask = source->subnet_source_mask;
272 	target->subnet_addr_fam    = source->subnet_addr_fam;
273 	memcpy(target->subnet_addr, source->subnet_addr, INET6_SIZE);
274 	target->subnet_validdata = 1;
275 }
276 
277 static void
278 delfunc(void *envptr, void *elemptr) {
279 	struct reply_info *elem = (struct reply_info *)elemptr;
280 	struct subnet_env *env = (struct subnet_env *)envptr;
281 	reply_info_parsedelete(elem, &env->alloc);
282 }
283 
284 static size_t
285 sizefunc(void *elemptr) {
286 	struct reply_info *elem  = (struct reply_info *)elemptr;
287 	return sizeof (struct reply_info) - sizeof (struct rrset_ref)
288 		+ elem->rrset_count * sizeof (struct rrset_ref)
289 		+ elem->rrset_count * sizeof (struct ub_packed_rrset_key *);
290 }
291 
292 /**
293  * Select tree from cache entry based on edns data.
294  * If for address family not present it will create a new one.
295  * NULL on failure to create. */
296 static struct addrtree*
297 get_tree(struct subnet_msg_cache_data *data, struct ecs_data *edns,
298 	struct subnet_env *env, struct config_file* cfg)
299 {
300 	struct addrtree *tree;
301 	if (edns->subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP4) {
302 		if (!data->tree4)
303 			data->tree4 = addrtree_create(
304 				cfg->max_client_subnet_ipv4, &delfunc,
305 				&sizefunc, env, cfg->max_ecs_tree_size_ipv4);
306 		tree = data->tree4;
307 	} else {
308 		if (!data->tree6)
309 			data->tree6 = addrtree_create(
310 				cfg->max_client_subnet_ipv6, &delfunc,
311 				&sizefunc, env, cfg->max_ecs_tree_size_ipv6);
312 		tree = data->tree6;
313 	}
314 	return tree;
315 }
316 
317 static void
318 update_cache(struct module_qstate *qstate, int id)
319 {
320 	struct msgreply_entry *mrep_entry;
321 	struct addrtree *tree;
322 	struct reply_info *rep;
323 	struct query_info qinf;
324 	struct subnet_env *sne = qstate->env->modinfo[id];
325 	struct subnet_qstate *sq = (struct subnet_qstate*)qstate->minfo[id];
326 	struct slabhash *subnet_msg_cache = sne->subnet_msg_cache;
327 	struct ecs_data *edns = &sq->ecs_client_in;
328 	size_t i;
329 
330 	/* We already calculated hash upon lookup */
331 	hashvalue_type h = qstate->minfo[id] ?
332 		((struct subnet_qstate*)qstate->minfo[id])->qinfo_hash :
333 		query_info_hash(&qstate->qinfo, qstate->query_flags);
334 	/* Step 1, general qinfo lookup */
335 	struct lruhash_entry *lru_entry = slabhash_lookup(subnet_msg_cache, h,
336 		&qstate->qinfo, 1);
337 	int need_to_insert = (lru_entry == NULL);
338 	if (!lru_entry) {
339 		void* data = calloc(1,
340 			sizeof(struct subnet_msg_cache_data));
341 		if(!data) {
342 			log_err("malloc failed");
343 			return;
344 		}
345 		qinf = qstate->qinfo;
346 		qinf.qname = memdup(qstate->qinfo.qname,
347 			qstate->qinfo.qname_len);
348 		if(!qinf.qname) {
349 			free(data);
350 			log_err("memdup failed");
351 			return;
352 		}
353 		mrep_entry = query_info_entrysetup(&qinf, data, h);
354 		free(qinf.qname); /* if qname 'consumed', it is set to NULL */
355 		if (!mrep_entry) {
356 			free(data);
357 			log_err("query_info_entrysetup failed");
358 			return;
359 		}
360 		lru_entry = &mrep_entry->entry;
361 		lock_rw_wrlock(&lru_entry->lock);
362 	}
363 	/* lru_entry->lock is locked regardless of how we got here,
364 	 * either from the slabhash_lookup, or above in the new allocated */
365 	/* Step 2, find the correct tree */
366 	if (!(tree = get_tree(lru_entry->data, edns, sne, qstate->env->cfg))) {
367 		lock_rw_unlock(&lru_entry->lock);
368 		log_err("Subnet cache insertion failed");
369 		return;
370 	}
371 	lock_quick_lock(&sne->alloc.lock);
372 	rep = reply_info_copy(qstate->return_msg->rep, &sne->alloc, NULL);
373 	lock_quick_unlock(&sne->alloc.lock);
374 	if (!rep) {
375 		lock_rw_unlock(&lru_entry->lock);
376 		log_err("Subnet cache insertion failed");
377 		return;
378 	}
379 
380 	/* store RRsets */
381 	for(i=0; i<rep->rrset_count; i++) {
382 		rep->ref[i].key = rep->rrsets[i];
383 		rep->ref[i].id = rep->rrsets[i]->id;
384 	}
385 	reply_info_set_ttls(rep, *qstate->env->now);
386 	rep->flags |= (BIT_RA | BIT_QR); /* fix flags to be sensible for */
387 	rep->flags &= ~(BIT_AA | BIT_CD);/* a reply based on the cache   */
388 	addrtree_insert(tree, (addrkey_t*)edns->subnet_addr,
389 		edns->subnet_source_mask,
390 		sq->ecs_server_in.subnet_scope_mask, rep,
391 		rep->ttl, *qstate->env->now);
392 
393 	lock_rw_unlock(&lru_entry->lock);
394 	if (need_to_insert) {
395 		slabhash_insert(subnet_msg_cache, h, lru_entry, lru_entry->data,
396 			NULL);
397 	}
398 }
399 
400 /** Lookup in cache and reply true iff reply is sent. */
401 static int
402 lookup_and_reply(struct module_qstate *qstate, int id, struct subnet_qstate *sq)
403 {
404 	struct lruhash_entry *e;
405 	struct module_env *env = qstate->env;
406 	struct subnet_env *sne = (struct subnet_env*)env->modinfo[id];
407 	hashvalue_type h = query_info_hash(&qstate->qinfo, qstate->query_flags);
408 	struct subnet_msg_cache_data *data;
409 	struct ecs_data *ecs = &sq->ecs_client_in;
410 	struct addrtree *tree;
411 	struct addrnode *node;
412 	uint8_t scope;
413 
414 	memset(&sq->ecs_client_out, 0, sizeof(sq->ecs_client_out));
415 
416 	if (sq) sq->qinfo_hash = h; /* Might be useful on cache miss */
417 	e = slabhash_lookup(sne->subnet_msg_cache, h, &qstate->qinfo, 1);
418 	if (!e) return 0; /* qinfo not in cache */
419 	data = e->data;
420 	tree = (ecs->subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP4)?
421 		data->tree4 : data->tree6;
422 	if (!tree) { /* qinfo in cache but not for this family */
423 		lock_rw_unlock(&e->lock);
424 		return 0;
425 	}
426 	node = addrtree_find(tree, (addrkey_t*)ecs->subnet_addr,
427 		ecs->subnet_source_mask, *env->now);
428 	if (!node) { /* plain old cache miss */
429 		lock_rw_unlock(&e->lock);
430 		return 0;
431 	}
432 
433 	qstate->return_msg = tomsg(NULL, &qstate->qinfo,
434 		(struct reply_info *)node->elem, qstate->region, *env->now, 0,
435 		env->scratch);
436 	scope = (uint8_t)node->scope;
437 	lock_rw_unlock(&e->lock);
438 
439 	if (!qstate->return_msg) { /* Failed allocation or expired TTL */
440 		return 0;
441 	}
442 
443 	if (sq->subnet_downstream) { /* relay to interested client */
444 		sq->ecs_client_out.subnet_scope_mask = scope;
445 		sq->ecs_client_out.subnet_addr_fam = ecs->subnet_addr_fam;
446 		sq->ecs_client_out.subnet_source_mask = ecs->subnet_source_mask;
447 		memcpy(&sq->ecs_client_out.subnet_addr, &ecs->subnet_addr,
448 			INET6_SIZE);
449 		sq->ecs_client_out.subnet_validdata = 1;
450 	}
451 	return 1;
452 }
453 
454 /**
455  * Test first bits of addresses for equality. Caller is responsible
456  * for making sure that both a and b are at least net/8 octets long.
457  * @param a: first address.
458  * @param a: seconds address.
459  * @param net: Number of bits to test.
460  * @return: 1 if equal, 0 otherwise.
461  */
462 static int
463 common_prefix(uint8_t *a, uint8_t *b, uint8_t net)
464 {
465 	size_t n = (size_t)net / 8;
466 	return !memcmp(a, b, n) && ((net % 8) == 0 || a[n] == b[n]);
467 }
468 
469 static enum module_ext_state
470 eval_response(struct module_qstate *qstate, int id, struct subnet_qstate *sq)
471 {
472 	struct subnet_env *sne = qstate->env->modinfo[id];
473 
474 	struct ecs_data *c_in  = &sq->ecs_client_in; /* rcvd from client */
475 	struct ecs_data *c_out = &sq->ecs_client_out;/* will send to client */
476 	struct ecs_data *s_in  = &sq->ecs_server_in; /* rcvd from auth */
477 	struct ecs_data *s_out = &sq->ecs_server_out;/* sent to auth */
478 
479 	memset(c_out, 0, sizeof(*c_out));
480 
481 	if (!qstate->return_msg) {
482 		/* already an answer and its not a message, but retain
483 		 * the actual rcode, instead of module_error, so send
484 		 * module_finished */
485 		return module_finished;
486 	}
487 
488 	/* We have not asked for subnet data */
489 	if (!sq->subnet_sent) {
490 		if (s_in->subnet_validdata)
491 			verbose(VERB_QUERY, "subnet: received spurious data");
492 		if (sq->subnet_downstream) /* Copy back to client */
493 			cp_edns_bad_response(c_out, c_in);
494 		return module_finished;
495 	}
496 
497 	/* subnet sent but nothing came back */
498 	if (!s_in->subnet_validdata) {
499 		/* The authority indicated no support for edns subnet. As a
500 		 * consequence the answer ended up in the regular cache. It
501 		 * is still usefull to put it in the edns subnet cache for
502 		 * when a client explicitly asks for subnet specific answer. */
503 		verbose(VERB_QUERY, "subnet: Authority indicates no support");
504 		if(!sq->started_no_cache_store) {
505 			lock_rw_wrlock(&sne->biglock);
506 			update_cache(qstate, id);
507 			lock_rw_unlock(&sne->biglock);
508 		}
509 		if (sq->subnet_downstream)
510 			cp_edns_bad_response(c_out, c_in);
511 		return module_finished;
512 	}
513 
514 	/* Being here means we have asked for and got a subnet specific
515 	 * answer. Also, the answer from the authority is not yet cached
516 	 * anywhere. */
517 
518 	/* can we accept response? */
519 	if(s_out->subnet_addr_fam != s_in->subnet_addr_fam ||
520 		s_out->subnet_source_mask != s_in->subnet_source_mask ||
521 		!common_prefix(s_out->subnet_addr, s_in->subnet_addr,
522 			s_out->subnet_source_mask))
523 	{
524 		/* we can not accept, restart query without option */
525 		verbose(VERB_QUERY, "subnet: forged data");
526 		s_out->subnet_validdata = 0;
527 		(void)edns_opt_list_remove(&qstate->edns_opts_back_out,
528 			qstate->env->cfg->client_subnet_opcode);
529 		sq->subnet_sent = 0;
530 		return module_restart_next;
531 	}
532 
533 	lock_rw_wrlock(&sne->biglock);
534 	if(!sq->started_no_cache_store) {
535 		update_cache(qstate, id);
536 	}
537 	sne->num_msg_nocache++;
538 	lock_rw_unlock(&sne->biglock);
539 
540 	if (sq->subnet_downstream) {
541 		/* Client wants to see the answer, echo option back
542 		 * and adjust the scope. */
543 		c_out->subnet_addr_fam = c_in->subnet_addr_fam;
544 		c_out->subnet_source_mask = c_in->subnet_source_mask;
545 		memcpy(&c_out->subnet_addr, &c_in->subnet_addr, INET6_SIZE);
546 		c_out->subnet_scope_mask = s_in->subnet_scope_mask;
547 		/* Limit scope returned to client to scope used for caching. */
548 		if(c_out->subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP4) {
549 			if(c_out->subnet_scope_mask >
550 				qstate->env->cfg->max_client_subnet_ipv4) {
551 				c_out->subnet_scope_mask =
552 					qstate->env->cfg->max_client_subnet_ipv4;
553 			}
554 		}
555 		else if(c_out->subnet_scope_mask >
556 				qstate->env->cfg->max_client_subnet_ipv6) {
557 				c_out->subnet_scope_mask =
558 					qstate->env->cfg->max_client_subnet_ipv6;
559 		}
560 		c_out->subnet_validdata = 1;
561 	}
562 	return module_finished;
563 }
564 
565 /** Parse EDNS opt data containing ECS */
566 static int
567 parse_subnet_option(struct edns_option* ecs_option, struct ecs_data* ecs)
568 {
569 	memset(ecs, 0, sizeof(*ecs));
570 	if (ecs_option->opt_len < 4)
571 		return 0;
572 
573 	ecs->subnet_addr_fam = sldns_read_uint16(ecs_option->opt_data);
574 	ecs->subnet_source_mask = ecs_option->opt_data[2];
575 	ecs->subnet_scope_mask = ecs_option->opt_data[3];
576 	/* remaining bytes indicate address */
577 
578 	/* validate input*/
579 	/* option length matches calculated length? */
580 	if (ecs_option->opt_len != (size_t)((ecs->subnet_source_mask+7)/8 + 4))
581 		return 0;
582 	if (ecs_option->opt_len - 4 > INET6_SIZE || ecs_option->opt_len == 0)
583 		return 0;
584 	if (ecs->subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP4) {
585 		if (ecs->subnet_source_mask > 32 || ecs->subnet_scope_mask > 32)
586 			return 0;
587 	} else if (ecs->subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP6) {
588 		if (ecs->subnet_source_mask > 128 ||
589 			ecs->subnet_scope_mask > 128)
590 			return 0;
591 	} else
592 		return 0;
593 
594 	/* valid ECS data, write to ecs_data */
595 	if (copy_clear(ecs->subnet_addr, INET6_SIZE, ecs_option->opt_data + 4,
596 		ecs_option->opt_len - 4, ecs->subnet_source_mask))
597 		return 0;
598 	ecs->subnet_validdata = 1;
599 	return 1;
600 }
601 
602 static void
603 subnet_option_from_ss(struct sockaddr_storage *ss, struct ecs_data* ecs,
604 	struct config_file* cfg)
605 {
606 	void* sinaddr;
607 
608 	/* Construct subnet option from original query */
609 	if(((struct sockaddr_in*)ss)->sin_family == AF_INET) {
610 		ecs->subnet_source_mask = cfg->max_client_subnet_ipv4;
611 		ecs->subnet_addr_fam = EDNSSUBNET_ADDRFAM_IP4;
612 		sinaddr = &((struct sockaddr_in*)ss)->sin_addr;
613 		if (!copy_clear( ecs->subnet_addr, INET6_SIZE,
614 			(uint8_t *)sinaddr, INET_SIZE,
615 			ecs->subnet_source_mask)) {
616 			ecs->subnet_validdata = 1;
617 		}
618 	}
619 #ifdef INET6
620 	else {
621 		ecs->subnet_source_mask = cfg->max_client_subnet_ipv6;
622 		ecs->subnet_addr_fam = EDNSSUBNET_ADDRFAM_IP6;
623 		sinaddr = &((struct sockaddr_in6*)ss)->sin6_addr;
624 		if (!copy_clear( ecs->subnet_addr, INET6_SIZE,
625 			(uint8_t *)sinaddr, INET6_SIZE,
626 			ecs->subnet_source_mask)) {
627 			ecs->subnet_validdata = 1;
628 		}
629 	}
630 #else
631 			/* We don't know how to handle ip6, just pass */
632 #endif /* INET6 */
633 }
634 
635 int
636 ecs_query_response(struct module_qstate* qstate, struct dns_msg* response,
637 	int id, void* ATTR_UNUSED(cbargs))
638 {
639 	struct subnet_qstate *sq;
640 
641 	if(!response || !(sq=(struct subnet_qstate*)qstate->minfo[id]))
642 		return 1;
643 
644 	if(sq->subnet_sent &&
645 		FLAGS_GET_RCODE(response->rep->flags) == LDNS_RCODE_REFUSED) {
646 		/* REFUSED response to ECS query, remove ECS option. */
647 		edns_opt_list_remove(&qstate->edns_opts_back_out,
648 			qstate->env->cfg->client_subnet_opcode);
649 		sq->subnet_sent = 0;
650 		memset(&sq->ecs_server_out, 0, sizeof(sq->ecs_server_out));
651 	}
652 	return 1;
653 }
654 
655 int
656 ecs_edns_back_parsed(struct module_qstate* qstate, int id,
657 	void* ATTR_UNUSED(cbargs))
658 {
659 	struct subnet_qstate *sq;
660 	struct edns_option* ecs_opt;
661 
662 	if(!(sq=(struct subnet_qstate*)qstate->minfo[id]))
663 		return 1;
664 	if((ecs_opt = edns_opt_list_find(
665 		qstate->edns_opts_back_in,
666 		qstate->env->cfg->client_subnet_opcode))) {
667 		if(parse_subnet_option(ecs_opt, &sq->ecs_server_in) &&
668 			sq->subnet_sent &&
669 			sq->ecs_server_in.subnet_validdata)
670 			/* Only skip global cache store if we sent an ECS option
671 			 * and received one back. Answers from non-whitelisted
672 			 * servers will end up in global cache. Answers for
673 			 * queries with 0 source will not (unless nameserver
674 			 * does not support ECS). */
675 			qstate->no_cache_store = 1;
676 	}
677 
678 	return 1;
679 }
680 
681 void
682 subnetmod_operate(struct module_qstate *qstate, enum module_ev event,
683 	int id, struct outbound_entry* outbound)
684 {
685 	struct subnet_env *sne = qstate->env->modinfo[id];
686 	struct subnet_qstate *sq = (struct subnet_qstate*)qstate->minfo[id];
687 
688 	verbose(VERB_QUERY, "subnet[module %d] operate: extstate:%s "
689 		"event:%s", id, strextstate(qstate->ext_state[id]),
690 		strmodulevent(event));
691 	log_query_info(VERB_QUERY, "subnet operate: query", &qstate->qinfo);
692 
693 	if((event == module_event_new || event == module_event_pass) &&
694 		sq == NULL) {
695 		struct edns_option* ecs_opt;
696 		if(!subnet_new_qstate(qstate, id)) {
697 			qstate->return_msg = NULL;
698 			qstate->ext_state[id] = module_finished;
699 			return;
700 		}
701 
702 		sq = (struct subnet_qstate*)qstate->minfo[id];
703 
704 		if((ecs_opt = edns_opt_list_find(
705 			qstate->edns_opts_front_in,
706 			qstate->env->cfg->client_subnet_opcode))) {
707 			if(!parse_subnet_option(ecs_opt, &sq->ecs_client_in)) {
708 				/* Wrongly formatted ECS option. RFC mandates to
709 				 * return FORMERROR. */
710 				qstate->return_rcode = LDNS_RCODE_FORMERR;
711 				qstate->ext_state[id] = module_finished;
712 				return;
713 			}
714 			sq->subnet_downstream = 1;
715 		}
716 		else if(qstate->mesh_info->reply_list) {
717 			subnet_option_from_ss(
718 				&qstate->mesh_info->reply_list->query_reply.addr,
719 				&sq->ecs_client_in, qstate->env->cfg);
720 		}
721 
722 		if(sq->ecs_client_in.subnet_validdata == 0) {
723 			/* No clients are interested in result or we could not
724 			 * parse it, we don't do client subnet */
725 			sq->ecs_server_out.subnet_validdata = 0;
726 			verbose(VERB_ALGO, "subnet: pass to next module");
727 			qstate->ext_state[id] = module_wait_module;
728 			return;
729 		}
730 
731 		/* Limit to minimum allowed source mask */
732 		if(sq->ecs_client_in.subnet_source_mask != 0 && (
733 			(sq->ecs_client_in.subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP4 &&
734 			 sq->ecs_client_in.subnet_source_mask < qstate->env->cfg->min_client_subnet_ipv4) ||
735 			(sq->ecs_client_in.subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP6 &&
736 			 sq->ecs_client_in.subnet_source_mask < qstate->env->cfg->min_client_subnet_ipv6))) {
737 				qstate->return_rcode = LDNS_RCODE_REFUSED;
738 				qstate->ext_state[id] = module_finished;
739 				return;
740 		}
741 
742 		lock_rw_wrlock(&sne->biglock);
743 		if (lookup_and_reply(qstate, id, sq)) {
744 			sne->num_msg_cache++;
745 			lock_rw_unlock(&sne->biglock);
746 			verbose(VERB_QUERY, "subnet: answered from cache");
747 			qstate->ext_state[id] = module_finished;
748 
749 			ecs_opt_list_append(&sq->ecs_client_out,
750 				&qstate->edns_opts_front_out, qstate);
751 			return;
752 		}
753 		lock_rw_unlock(&sne->biglock);
754 
755 		sq->ecs_server_out.subnet_addr_fam =
756 			sq->ecs_client_in.subnet_addr_fam;
757 		sq->ecs_server_out.subnet_source_mask =
758 			sq->ecs_client_in.subnet_source_mask;
759 		/* Limit source prefix to configured maximum */
760 		if(sq->ecs_server_out.subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP4
761 			&& sq->ecs_server_out.subnet_source_mask >
762 			qstate->env->cfg->max_client_subnet_ipv4)
763 			sq->ecs_server_out.subnet_source_mask =
764 				qstate->env->cfg->max_client_subnet_ipv4;
765 		else if(sq->ecs_server_out.subnet_addr_fam == EDNSSUBNET_ADDRFAM_IP6
766 			&& sq->ecs_server_out.subnet_source_mask >
767 			qstate->env->cfg->max_client_subnet_ipv6)
768 			sq->ecs_server_out.subnet_source_mask =
769 				qstate->env->cfg->max_client_subnet_ipv6;
770 		/* Safe to copy completely, even if the source is limited by the
771 		 * configuration. ecs_opt_list_append() will limit the address.
772 		 * */
773 		memcpy(&sq->ecs_server_out.subnet_addr,
774 			sq->ecs_client_in.subnet_addr, INET6_SIZE);
775 		sq->ecs_server_out.subnet_scope_mask = 0;
776 		sq->ecs_server_out.subnet_validdata = 1;
777 		if(sq->ecs_server_out.subnet_source_mask != 0 &&
778 			qstate->env->cfg->client_subnet_always_forward &&
779 			sq->subnet_downstream)
780 			/* ECS specific data required, do not look at the global
781 			 * cache in other modules. */
782 			qstate->no_cache_lookup = 1;
783 
784 		/* pass request to next module */
785 		verbose(VERB_ALGO,
786 			"subnet: not found in cache. pass to next module");
787 		qstate->ext_state[id] = module_wait_module;
788 		return;
789 	}
790 	/* Query handed back by next module, we have a 'final' answer */
791 	if(sq && event == module_event_moddone) {
792 		qstate->ext_state[id] = eval_response(qstate, id, sq);
793 		if(qstate->ext_state[id] == module_finished &&
794 			qstate->return_msg) {
795 			ecs_opt_list_append(&sq->ecs_client_out,
796 				&qstate->edns_opts_front_out, qstate);
797 		}
798 		qstate->no_cache_store = sq->started_no_cache_store;
799 		return;
800 	}
801 	if(sq && outbound) {
802 		return;
803 	}
804 	/* We are being revisited */
805 	if(event == module_event_pass || event == module_event_new) {
806 		/* Just pass it on, we already did the work */
807 		verbose(VERB_ALGO, "subnet: pass to next module");
808 		qstate->ext_state[id] = module_wait_module;
809 		return;
810 	}
811 	if(!sq && (event == module_event_moddone)) {
812 		/* during priming, module done but we never started */
813 		qstate->ext_state[id] = module_finished;
814 		return;
815 	}
816 	log_err("subnet: bad event %s", strmodulevent(event));
817 	qstate->ext_state[id] = module_error;
818 	return;
819 }
820 
821 void
822 subnetmod_clear(struct module_qstate *ATTR_UNUSED(qstate),
823 	int ATTR_UNUSED(id))
824 {
825 	/* qstate has no data outside region */
826 }
827 
828 void
829 subnetmod_inform_super(struct module_qstate *ATTR_UNUSED(qstate),
830 	int ATTR_UNUSED(id), struct module_qstate *ATTR_UNUSED(super))
831 {
832 	/* Not used */
833 }
834 
835 size_t
836 subnetmod_get_mem(struct module_env *env, int id)
837 {
838 	struct subnet_env *sn_env = env->modinfo[id];
839 	if (!sn_env) return 0;
840 	return sizeof(*sn_env) +
841 		slabhash_get_mem(sn_env->subnet_msg_cache) +
842 		ecs_whitelist_get_mem(sn_env->whitelist);
843 }
844 
845 /**
846  * The module function block
847  */
848 static struct module_func_block subnetmod_block = {
849 	"subnet", &subnetmod_init, &subnetmod_deinit, &subnetmod_operate,
850 	&subnetmod_inform_super, &subnetmod_clear, &subnetmod_get_mem
851 };
852 
853 struct module_func_block*
854 subnetmod_get_funcblock(void)
855 {
856 	return &subnetmod_block;
857 }
858 
859 /** Wrappers for static functions to unit test */
860 size_t
861 unittest_wrapper_subnetmod_sizefunc(void *elemptr)
862 {
863 	return sizefunc(elemptr);
864 }
865 
866 #endif  /* CLIENT_SUBNET */
867