2 * dns64/dns64.c - DNS64 module
4 * Copyright (c) 2009, Viagénie. All rights reserved.
6 * This software is open source.
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39 * This file contains a module that performs DNS64 query processing.
43 #include "dns64/dns64.h"
44 #include "services/cache/dns.h"
45 #include "services/cache/rrset.h"
46 #include "util/config_file.h"
47 #include "util/data/msgreply.h"
48 #include "util/fptr_wlist.h"
49 #include "util/net_help.h"
50 #include "util/regional.h"
52 /******************************************************************************
56 ******************************************************************************/
59 * This is the default DNS64 prefix that is used whent he dns64 module is listed
60 * in module-config but when the dns64-prefix variable is not present.
62 static const char DEFAULT_DNS64_PREFIX[] = "64:ff9b::/96";
65 * Maximum length of a domain name in a PTR query in the .in-addr.arpa tree.
67 #define MAX_PTR_QNAME_IPV4 30
70 * Per-query module-specific state. This is usually a dynamically-allocated
71 * structure, but in our case we only need to store one variable describing the
72 * state the query is in. So we repurpose the minfo pointer by storing an
76 DNS64_INTERNAL_QUERY, /**< Internally-generated query, no DNS64
78 DNS64_NEW_QUERY, /**< Query for which we're the first module in
80 DNS64_SUBQUERY_FINISHED /**< Query for which we generated a sub-query, and
81 for which this sub-query is finished. */
85 /******************************************************************************
89 ******************************************************************************/
92 * This structure contains module configuration information. One instance of
93 * this structure exists per instance of the module. Normally there is only one
94 * instance of the module.
98 * DNS64 prefix address. We're using a full sockaddr instead of just an
99 * in6_addr because we can reuse Unbound's generic string parsing functions.
100 * It will always contain a sockaddr_in6, and only the sin6_addr member will
103 struct sockaddr_storage prefix_addr;
106 * This is always sizeof(sockaddr_in6).
108 socklen_t prefix_addrlen;
111 * This is the CIDR length of the prefix. It needs to be between 0 and 96.
117 /******************************************************************************
119 * UTILITY FUNCTIONS *
121 ******************************************************************************/
124 * Generic macro for swapping two variables.
126 * \param t Type of the variables. (e.g. int)
127 * \param a First variable.
128 * \param b Second variable.
130 * \warning Do not attempt something foolish such as swap(int,a++,b++)!
132 #define swap(t,a,b) do {t x = a; a = b; b = x;} while(0)
137 * \param begin Points to the first character of the string.
138 * \param end Points one past the last character of the string.
141 reverse(char* begin, char* end)
143 while ( begin < --end ) {
144 swap(char, *begin, *end);
150 * Convert an unsigned integer to a string. The point of this function is that
151 * of being faster than sprintf().
153 * \param n The number to be converted.
154 * \param s The result will be written here. Must be large enough, be careful!
156 * \return The number of characters written.
159 uitoa(unsigned n, char* s)
163 *ss++ = '0' + n % 10;
170 * Extract an IPv4 address embedded in the IPv6 address \a ipv6 at offset \a
171 * offset (in bits). Note that bits are not necessarily aligned on bytes so we
172 * need to be careful.
174 * \param ipv6 IPv6 address represented as a 128-bit array in big-endian
176 * \param offset Index of the MSB of the IPv4 address embedded in the IPv6
180 extract_ipv4(const uint8_t ipv6[16], const int offset)
182 uint32_t ipv4 = (uint32_t)ipv6[offset/8+0] << (24 + (offset%8))
183 | (uint32_t)ipv6[offset/8+1] << (16 + (offset%8))
184 | (uint32_t)ipv6[offset/8+2] << ( 8 + (offset%8))
185 | (uint32_t)ipv6[offset/8+3] << ( 0 + (offset%8));
187 ipv4 |= (uint32_t)ipv6[offset/8+4] >> (8 - offset%8);
192 * Builds the PTR query name corresponding to an IPv4 address. For example,
193 * given the number 3,464,175,361, this will build the string
194 * "\03206\03123\0231\011\07in-addr\04arpa".
196 * \param ipv4 IPv4 address represented as an unsigned 32-bit number.
197 * \param ptr The result will be written here. Must be large enough, be
200 * \return The number of characters written.
203 ipv4_to_ptr(uint32_t ipv4, char ptr[MAX_PTR_QNAME_IPV4])
205 static const char IPV4_PTR_SUFFIX[] = "\07in-addr\04arpa";
209 for (i = 0; i < 4; ++i) {
210 *c = uitoa((unsigned int)(ipv4 % 256), c + 1);
215 memmove(c, IPV4_PTR_SUFFIX, sizeof(IPV4_PTR_SUFFIX));
217 return c + sizeof(IPV4_PTR_SUFFIX) - ptr;
221 * Converts an IPv6-related domain name string from a PTR query into an IPv6
222 * address represented as a 128-bit array.
224 * \param ptr The domain name. (e.g. "\011[...]\010\012\016\012\03ip6\04arpa")
225 * \param ipv6 The result will be written here, in network byte order.
227 * \return 1 on success, 0 on failure.
230 ptr_to_ipv6(const char* ptr, uint8_t ipv6[16])
234 for (i = 0; i < 64; i++) {
240 if (ptr[i] >= '0' && ptr[i] <= '9') {
242 } else if (ptr[i] >= 'a' && ptr[i] <= 'f') {
243 x = ptr[i] - 'a' + 10;
244 } else if (ptr[i] >= 'A' && ptr[i] <= 'F') {
245 x = ptr[i] - 'A' + 10;
250 ipv6[15-i/4] |= x << (2 * ((i-1) % 4));
257 * Synthesize an IPv6 address based on an IPv4 address and the DNS64 prefix.
259 * \param prefix_addr DNS64 prefix address.
260 * \param prefix_net CIDR length of the DNS64 prefix. Must be between 0 and 96.
261 * \param a IPv4 address.
262 * \param aaaa IPv6 address. The result will be written here.
265 synthesize_aaaa(const uint8_t prefix_addr[16], int prefix_net,
266 const uint8_t a[4], uint8_t aaaa[16])
268 memcpy(aaaa, prefix_addr, 16);
269 aaaa[prefix_net/8+0] |= a[0] >> (0+prefix_net%8);
270 aaaa[prefix_net/8+1] |= a[0] << (8-prefix_net%8);
271 aaaa[prefix_net/8+1] |= a[1] >> (0+prefix_net%8);
272 aaaa[prefix_net/8+2] |= a[1] << (8-prefix_net%8);
273 aaaa[prefix_net/8+2] |= a[2] >> (0+prefix_net%8);
274 aaaa[prefix_net/8+3] |= a[2] << (8-prefix_net%8);
275 aaaa[prefix_net/8+3] |= a[3] >> (0+prefix_net%8);
276 if (prefix_net/8+4 < 16) /* <-- my beautiful symmetry is destroyed! */
277 aaaa[prefix_net/8+4] |= a[3] << (8-prefix_net%8);
281 /******************************************************************************
283 * DNS64 MODULE FUNCTIONS *
285 ******************************************************************************/
288 * This function applies the configuration found in the parsed configuration
289 * file \a cfg to this instance of the dns64 module. Currently only the DNS64
290 * prefix (a.k.a. Pref64) is configurable.
292 * \param dns64_env Module-specific global parameters.
293 * \param cfg Parsed configuration file.
296 dns64_apply_cfg(struct dns64_env* dns64_env, struct config_file* cfg)
298 verbose(VERB_ALGO, "dns64-prefix: %s", cfg->dns64_prefix);
299 if (!netblockstrtoaddr(cfg->dns64_prefix ? cfg->dns64_prefix :
300 DEFAULT_DNS64_PREFIX, 0, &dns64_env->prefix_addr,
301 &dns64_env->prefix_addrlen, &dns64_env->prefix_net)) {
302 log_err("cannot parse dns64-prefix netblock: %s", cfg->dns64_prefix);
305 if (!addr_is_ip6(&dns64_env->prefix_addr, dns64_env->prefix_addrlen)) {
306 log_err("dns64_prefix is not IPv6: %s", cfg->dns64_prefix);
309 if (dns64_env->prefix_net < 0 || dns64_env->prefix_net > 96) {
310 log_err("dns64-prefix length it not between 0 and 96: %s",
318 * Initializes this instance of the dns64 module.
320 * \param env Global state of all module instances.
321 * \param id This instance's ID number.
324 dns64_init(struct module_env* env, int id)
326 struct dns64_env* dns64_env =
327 (struct dns64_env*)calloc(1, sizeof(struct dns64_env));
329 log_err("malloc failure");
332 env->modinfo[id] = (void*)dns64_env;
333 if (!dns64_apply_cfg(dns64_env, env->cfg)) {
334 log_err("dns64: could not apply configuration settings.");
341 * Deinitializes this instance of the dns64 module.
343 * \param env Global state of all module instances.
344 * \param id This instance's ID number.
347 dns64_deinit(struct module_env* env, int id)
351 free(env->modinfo[id]);
352 env->modinfo[id] = NULL;
356 * Handle PTR queries for IPv6 addresses. If the address belongs to the DNS64
357 * prefix, we must do a PTR query for the corresponding IPv4 address instead.
359 * \param qstate Query state structure.
360 * \param id This module instance's ID number.
362 * \return The new state of the query.
364 static enum module_ext_state
365 handle_ipv6_ptr(struct module_qstate* qstate, int id)
367 struct dns64_env* dns64_env = (struct dns64_env*)qstate->env->modinfo[id];
368 struct module_qstate* subq = NULL;
369 struct query_info qinfo;
370 struct sockaddr_in6 sin6;
372 /* Convert the PTR query string to an IPv6 address. */
373 memset(&sin6, 0, sizeof(sin6));
374 sin6.sin6_family = AF_INET6;
375 if (!ptr_to_ipv6((char*)qstate->qinfo.qname, sin6.sin6_addr.s6_addr))
376 return module_wait_module; /* Let other module handle this. */
379 * If this IPv6 address is not part of our DNS64 prefix, then we don't need
380 * to do anything. Let another module handle the query.
382 if (addr_in_common((struct sockaddr_storage*)&sin6, 128,
383 &dns64_env->prefix_addr, dns64_env->prefix_net,
384 (socklen_t)sizeof(sin6)) != dns64_env->prefix_net)
385 return module_wait_module;
387 verbose(VERB_ALGO, "dns64: rewrite PTR record");
390 * Create a new PTR query info for the domain name corresponding to the IPv4
391 * address corresponding to the IPv6 address corresponding to the original
392 * PTR query domain name.
394 qinfo = qstate->qinfo;
395 if (!(qinfo.qname = regional_alloc(qstate->region, MAX_PTR_QNAME_IPV4)))
397 qinfo.qname_len = ipv4_to_ptr(extract_ipv4(sin6.sin6_addr.s6_addr,
398 dns64_env->prefix_net), (char*)qinfo.qname);
400 /* Create the new sub-query. */
401 fptr_ok(fptr_whitelist_modenv_attach_sub(qstate->env->attach_sub));
402 if(!(*qstate->env->attach_sub)(qstate, &qinfo, qstate->query_flags, 0, 0,
407 subq->ext_state[id] = module_state_initial;
408 subq->minfo[id] = NULL;
411 return module_wait_subquery;
414 /** allocate (special) rrset keys, return 0 on error */
416 repinfo_alloc_rrset_keys(struct reply_info* rep,
417 struct regional* region)
420 for(i=0; i<rep->rrset_count; i++) {
422 rep->rrsets[i] = (struct ub_packed_rrset_key*)
423 regional_alloc(region,
424 sizeof(struct ub_packed_rrset_key));
426 memset(rep->rrsets[i], 0,
427 sizeof(struct ub_packed_rrset_key));
428 rep->rrsets[i]->entry.key = rep->rrsets[i];
431 else return 0;/* rep->rrsets[i] = alloc_special_obtain(alloc);*/
434 rep->rrsets[i]->entry.data = NULL;
439 static enum module_ext_state
440 generate_type_A_query(struct module_qstate* qstate, int id)
442 struct module_qstate* subq = NULL;
443 struct query_info qinfo;
445 verbose(VERB_ALGO, "dns64: query A record");
447 /* Create a new query info. */
448 qinfo = qstate->qinfo;
449 qinfo.qtype = LDNS_RR_TYPE_A;
451 /* Start the sub-query. */
452 fptr_ok(fptr_whitelist_modenv_attach_sub(qstate->env->attach_sub));
453 if(!(*qstate->env->attach_sub)(qstate, &qinfo, qstate->query_flags, 0,
456 verbose(VERB_ALGO, "dns64: sub-query creation failed");
461 subq->ext_state[id] = module_state_initial;
462 subq->minfo[id] = NULL;
465 return module_wait_subquery;
469 * Handles the "pass" event for a query. This event is received when a new query
470 * is received by this module. The query may have been generated internally by
471 * another module, in which case we don't want to do any special processing
472 * (this is an interesting discussion topic), or it may be brand new, e.g.
473 * received over a socket, in which case we do want to apply DNS64 processing.
475 * \param qstate A structure representing the state of the query that has just
476 * received the "pass" event.
477 * \param id This module's instance ID.
479 * \return The new state of the query.
481 static enum module_ext_state
482 handle_event_pass(struct module_qstate* qstate, int id)
484 if ((uintptr_t)qstate->minfo[id] == DNS64_NEW_QUERY
485 && qstate->qinfo.qtype == LDNS_RR_TYPE_PTR
486 && qstate->qinfo.qname_len == 74
487 && !strcmp((char*)&qstate->qinfo.qname[64], "\03ip6\04arpa"))
488 /* Handle PTR queries for IPv6 addresses. */
489 return handle_ipv6_ptr(qstate, id);
491 if (qstate->env->cfg->dns64_synthall &&
492 (uintptr_t)qstate->minfo[id] == DNS64_NEW_QUERY
493 && qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA)
494 return generate_type_A_query(qstate, id);
496 /* We are finished when our sub-query is finished. */
497 if ((uintptr_t)qstate->minfo[id] == DNS64_SUBQUERY_FINISHED)
498 return module_finished;
500 /* Otherwise, pass request to next module. */
501 verbose(VERB_ALGO, "dns64: pass to next module");
502 return module_wait_module;
506 * Handles the "done" event for a query. We need to analyze the response and
507 * maybe issue a new sub-query for the A record.
509 * \param qstate A structure representing the state of the query that has just
510 * received the "pass" event.
511 * \param id This module's instance ID.
513 * \return The new state of the query.
515 static enum module_ext_state
516 handle_event_moddone(struct module_qstate* qstate, int id)
519 * In many cases we have nothing special to do. From most to least common:
521 * - An internal query.
522 * - A query for a record type other than AAAA.
523 * - CD FLAG was set on querier
524 * - An AAAA query for which an error was returned.(qstate.return_rcode)
525 * -> treated as servfail thus synthesize (sec 5.1.3 6147), thus
526 * synthesize in (sec 5.1.2 of RFC6147).
527 * - A successful AAAA query with an answer.
529 if ( (enum dns64_qstate)qstate->minfo[id] == DNS64_INTERNAL_QUERY
530 || qstate->qinfo.qtype != LDNS_RR_TYPE_AAAA
531 || (qstate->query_flags & BIT_CD)
532 || (qstate->return_msg &&
533 qstate->return_msg->rep &&
534 reply_find_answer_rrset(&qstate->qinfo,
535 qstate->return_msg->rep)))
536 return module_finished;
538 /* So, this is a AAAA noerror/nodata answer */
539 return generate_type_A_query(qstate, id);
543 * This is the module's main() function. It gets called each time a query
544 * receives an event which we may need to handle. We respond by updating the
545 * state of the query.
547 * \param qstate Structure containing the state of the query.
548 * \param event Event that has just been received.
549 * \param id This module's instance ID.
550 * \param outbound State of a DNS query on an authoritative server. We never do
551 * our own queries ourselves (other modules do it for us), so
555 dns64_operate(struct module_qstate* qstate, enum module_ev event, int id,
556 struct outbound_entry* outbound)
559 verbose(VERB_QUERY, "dns64[module %d] operate: extstate:%s event:%s",
560 id, strextstate(qstate->ext_state[id]),
561 strmodulevent(event));
562 log_query_info(VERB_QUERY, "dns64 operate: query", &qstate->qinfo);
565 case module_event_new:
566 /* Tag this query as being new and fall through. */
567 qstate->minfo[id] = (void*)DNS64_NEW_QUERY;
568 case module_event_pass:
569 qstate->ext_state[id] = handle_event_pass(qstate, id);
571 case module_event_moddone:
572 qstate->ext_state[id] = handle_event_moddone(qstate, id);
575 qstate->ext_state[id] = module_finished;
581 dns64_synth_aaaa_data(const struct ub_packed_rrset_key* fk,
582 const struct packed_rrset_data* fd,
583 struct ub_packed_rrset_key *dk,
584 struct packed_rrset_data **dd_out, struct regional *region,
585 struct dns64_env* dns64_env )
587 struct packed_rrset_data *dd;
590 * Create synthesized AAAA RR set data. We need to allocated extra memory
591 * for the RRs themselves. Each RR has a length, TTL, pointer to wireformat
592 * data, 2 bytes of data length, and 16 bytes of IPv6 address.
594 if(fd->count > RR_COUNT_MAX) {
596 return; /* integer overflow protection in alloc */
598 if (!(dd = *dd_out = regional_alloc(region,
599 sizeof(struct packed_rrset_data)
600 + fd->count * (sizeof(size_t) + sizeof(time_t) +
601 sizeof(uint8_t*) + 2 + 16)))) {
602 log_err("out of memory");
606 /* Copy attributes from A RR set. */
608 dd->count = fd->count;
610 dd->trust = fd->trust;
611 dd->security = fd->security;
614 * Synthesize AAAA records. Adjust pointers in structure.
617 (size_t*)((uint8_t*)dd + sizeof(struct packed_rrset_data));
618 dd->rr_data = (uint8_t**)&dd->rr_len[dd->count];
619 dd->rr_ttl = (time_t*)&dd->rr_data[dd->count];
620 for(i = 0; i < fd->count; ++i) {
621 if (fd->rr_len[i] != 6 || fd->rr_data[i][0] != 0
622 || fd->rr_data[i][1] != 4) {
628 (uint8_t*)&dd->rr_ttl[dd->count] + 18*i;
629 dd->rr_data[i][0] = 0;
630 dd->rr_data[i][1] = 16;
632 ((struct sockaddr_in6*)&dns64_env->prefix_addr)->sin6_addr.s6_addr,
633 dns64_env->prefix_net, &fd->rr_data[i][2],
634 &dd->rr_data[i][2] );
635 dd->rr_ttl[i] = fd->rr_ttl[i];
639 * Create synthesized AAAA RR set key. This is mostly just bookkeeping,
640 * nothing interesting here.
648 dk->rk.dname = (uint8_t*)regional_alloc_init(region,
649 fk->rk.dname, fk->rk.dname_len);
652 log_err("out of memory");
657 dk->rk.type = htons(LDNS_RR_TYPE_AAAA);
658 memset(&dk->entry, 0, sizeof(dk->entry));
660 dk->entry.hash = rrset_key_hash(&dk->rk);
666 * Synthesize an AAAA RR set from an A sub-query's answer and add it to the
667 * original empty response.
669 * \param id This module's instance ID.
670 * \param super Original AAAA query.
671 * \param qstate A query.
674 dns64_adjust_a(int id, struct module_qstate* super, struct module_qstate* qstate)
676 struct dns64_env* dns64_env = (struct dns64_env*)super->env->modinfo[id];
677 struct reply_info *rep, *cp;
679 struct packed_rrset_data* fd, *dd;
680 struct ub_packed_rrset_key* fk, *dk;
682 verbose(VERB_ALGO, "converting A answers to AAAA answers");
684 log_assert(super->region);
685 log_assert(qstate->return_msg);
686 log_assert(qstate->return_msg->rep);
688 /* If dns64-synthall is enabled, return_msg is not initialized */
689 if(!super->return_msg) {
690 super->return_msg = (struct dns_msg*)regional_alloc(
691 super->region, sizeof(struct dns_msg));
692 if(!super->return_msg)
694 memset(super->return_msg, 0, sizeof(*super->return_msg));
695 super->return_msg->qinfo = super->qinfo;
698 rep = qstate->return_msg->rep;
701 * Build the actual reply.
703 cp = construct_reply_info_base(super->region, rep->flags, rep->qdcount,
704 rep->ttl, rep->prefetch_ttl, rep->an_numrrsets, rep->ns_numrrsets,
705 rep->ar_numrrsets, rep->rrset_count, rep->security);
709 /* allocate ub_key structures special or not */
710 if(!repinfo_alloc_rrset_keys(cp, super->region)) {
714 /* copy everything and replace A by AAAA */
715 for(i=0; i<cp->rrset_count; i++) {
718 fd = (struct packed_rrset_data*)fk->entry.data;
722 if(i<rep->an_numrrsets && fk->rk.type == htons(LDNS_RR_TYPE_A)) {
723 /* also sets dk->entry.hash */
724 dns64_synth_aaaa_data(fk, fd, dk, &dd, super->region, dns64_env);
727 /* Delete negative AAAA record from cache stored by
728 * the iterator module */
729 rrset_cache_remove(super->env->rrset_cache, dk->rk.dname,
730 dk->rk.dname_len, LDNS_RR_TYPE_AAAA,
731 LDNS_RR_CLASS_IN, 0);
733 dk->entry.hash = fk->entry.hash;
734 dk->rk.dname = (uint8_t*)regional_alloc_init(super->region,
735 fk->rk.dname, fk->rk.dname_len);
740 s = packed_rrset_sizeof(fd);
741 dd = (struct packed_rrset_data*)regional_alloc_init(
742 super->region, fd, s);
748 packed_rrset_ptr_fixup(dd);
749 dk->entry.data = (void*)dd;
752 /* Commit changes. */
753 super->return_msg->rep = cp;
757 * Generate a response for the original IPv6 PTR query based on an IPv4 PTR
758 * sub-query's response.
760 * \param qstate IPv4 PTR sub-query.
761 * \param super Original IPv6 PTR query.
764 dns64_adjust_ptr(struct module_qstate* qstate, struct module_qstate* super)
766 struct ub_packed_rrset_key* answer;
768 verbose(VERB_ALGO, "adjusting PTR reply");
770 /* Copy the sub-query's reply to the parent. */
771 if (!(super->return_msg = (struct dns_msg*)regional_alloc(super->region,
772 sizeof(struct dns_msg))))
774 super->return_msg->qinfo = super->qinfo;
775 super->return_msg->rep = reply_info_copy(qstate->return_msg->rep, NULL,
779 * Adjust the domain name of the answer RR set so that it matches the
780 * initial query's domain name.
782 answer = reply_find_answer_rrset(&qstate->qinfo, super->return_msg->rep);
784 answer->rk.dname = super->qinfo.qname;
785 answer->rk.dname_len = super->qinfo.qname_len;
789 * This function is called when a sub-query finishes to inform the parent query.
791 * We issue two kinds of sub-queries: PTR and A.
793 * \param qstate State of the sub-query.
794 * \param id This module's instance ID.
795 * \param super State of the super-query.
798 dns64_inform_super(struct module_qstate* qstate, int id,
799 struct module_qstate* super)
801 log_query_info(VERB_ALGO, "dns64: inform_super, sub is",
803 log_query_info(VERB_ALGO, "super is", &super->qinfo);
806 * Signal that the sub-query is finished, no matter whether we are
807 * successful or not. This lets the state machine terminate.
809 super->minfo[id] = (void*)DNS64_SUBQUERY_FINISHED;
811 /* If there is no successful answer, we're done. */
812 if (qstate->return_rcode != LDNS_RCODE_NOERROR
813 || !qstate->return_msg
814 || !qstate->return_msg->rep
815 || !reply_find_answer_rrset(&qstate->qinfo,
816 qstate->return_msg->rep))
819 /* Generate a response suitable for the original query. */
820 if (qstate->qinfo.qtype == LDNS_RR_TYPE_A) {
821 dns64_adjust_a(id, super, qstate);
823 log_assert(qstate->qinfo.qtype == LDNS_RR_TYPE_PTR);
824 dns64_adjust_ptr(qstate, super);
827 /* Store the generated response in cache. */
828 if (!dns_cache_store(super->env, &super->qinfo, super->return_msg->rep,
829 0, 0, 0, NULL, super->query_flags))
830 log_err("out of memory");
834 * Clear module-specific data from query state. Since we do not allocate memory,
835 * it's just a matter of setting a pointer to NULL.
837 * \param qstate Query state.
838 * \param id This module's instance ID.
841 dns64_clear(struct module_qstate* qstate, int id)
843 qstate->minfo[id] = NULL;
847 * Returns the amount of global memory that this module uses, not including
850 * \param env Module environment.
851 * \param id This module's instance ID.
854 dns64_get_mem(struct module_env* env, int id)
856 struct dns64_env* dns64_env = (struct dns64_env*)env->modinfo[id];
859 return sizeof(*dns64_env);
863 * The dns64 function block.
865 static struct module_func_block dns64_block = {
867 &dns64_init, &dns64_deinit, &dns64_operate, &dns64_inform_super,
868 &dns64_clear, &dns64_get_mem
872 * Function for returning the above function block.
874 struct module_func_block *
875 dns64_get_funcblock(void)