2 * util/data/msgencode.c - Encode DNS messages, queries and replies.
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
6 * This software is open source.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 * This file contains a routines to encode DNS messages.
43 #include "util/data/msgencode.h"
44 #include "util/data/msgreply.h"
45 #include "util/data/msgparse.h"
46 #include "util/data/dname.h"
48 #include "util/regional.h"
49 #include "util/net_help.h"
50 #include "sldns/sbuffer.h"
51 #include "services/localzone.h"
58 /** return code that means the function ran out of memory. negative so it does
59 * not conflict with DNS rcodes. */
60 #define RETVAL_OUTMEM -2
61 /** return code that means the data did not fit (completely) in the packet */
62 #define RETVAL_TRUNC -4
63 /** return code that means all is peachy keen. Equal to DNS rcode NOERROR */
67 * Data structure to help domain name compression in outgoing messages.
68 * A tree of dnames and their offsets in the packet is kept.
69 * It is kept sorted, not canonical, but by label at least, so that after
70 * a lookup of a name you know its closest match, and the parent from that
71 * closest match. These are possible compression targets.
73 * It is a binary tree, not a rbtree or balanced tree, as the effort
74 * of keeping it balanced probably outweighs usefulness (given typical
77 struct compress_tree_node {
78 /** left node in tree, all smaller to this */
79 struct compress_tree_node* left;
80 /** right node in tree, all larger than this */
81 struct compress_tree_node* right;
83 /** the parent node - not for tree, but zone parent. One less label */
84 struct compress_tree_node* parent;
85 /** the domain name for this node. Pointer to uncompressed memory. */
87 /** number of labels in domain name, kept to help compare func. */
89 /** offset in packet that points to this dname */
94 * Find domain name in tree, returns exact and closest match.
95 * @param tree: root of tree.
96 * @param dname: pointer to uncompressed dname.
97 * @param labs: number of labels in domain name.
98 * @param match: closest or exact match.
99 * guaranteed to be smaller or equal to the sought dname.
100 * can be null if the tree is empty.
101 * @param matchlabels: number of labels that match with closest match.
102 * can be zero is there is no match.
103 * @param insertpt: insert location for dname, if not found.
104 * @return: 0 if no exact match.
107 compress_tree_search(struct compress_tree_node** tree, uint8_t* dname,
108 int labs, struct compress_tree_node** match, int* matchlabels,
109 struct compress_tree_node*** insertpt)
112 struct compress_tree_node* p = *tree;
113 struct compress_tree_node* close = 0;
114 struct compress_tree_node** prev = tree;
116 if((c = dname_lab_cmp(dname, labs, p->dname, p->labs, &n))
127 close = p; /* p->dname is smaller than dname */
133 *matchlabels = closen;
139 * Lookup a domain name in compression tree.
140 * @param tree: root of tree (not the node with '.').
141 * @param dname: pointer to uncompressed dname.
142 * @param labs: number of labels in domain name.
143 * @param insertpt: insert location for dname, if not found.
144 * @return: 0 if not found or compress treenode with best compression.
146 static struct compress_tree_node*
147 compress_tree_lookup(struct compress_tree_node** tree, uint8_t* dname,
148 int labs, struct compress_tree_node*** insertpt)
150 struct compress_tree_node* p;
153 return 0; /* do not compress root node */
154 if(compress_tree_search(tree, dname, labs, &p, &m, insertpt)) {
158 /* return some ancestor of p that compresses well. */
160 /* www.example.com. (labs=4) matched foo.example.com.(labs=4)
161 * then matchcount = 3. need to go up. */
162 while(p && p->labs > m)
170 * Create node for domain name compression tree.
171 * @param dname: pointer to uncompressed dname (stored in tree).
172 * @param labs: number of labels in dname.
173 * @param offset: offset into packet for dname.
174 * @param region: how to allocate memory for new node.
175 * @return new node or 0 on malloc failure.
177 static struct compress_tree_node*
178 compress_tree_newnode(uint8_t* dname, int labs, size_t offset,
179 struct regional* region)
181 struct compress_tree_node* n = (struct compress_tree_node*)
182 regional_alloc(region, sizeof(struct compress_tree_node));
194 * Store domain name and ancestors into compression tree.
195 * @param dname: pointer to uncompressed dname (stored in tree).
196 * @param labs: number of labels in dname.
197 * @param offset: offset into packet for dname.
198 * @param region: how to allocate memory for new node.
199 * @param closest: match from previous lookup, used to compress dname.
200 * may be NULL if no previous match.
201 * if the tree has an ancestor of dname already, this must be it.
202 * @param insertpt: where to insert the dname in tree.
203 * @return: 0 on memory error.
206 compress_tree_store(uint8_t* dname, int labs, size_t offset,
207 struct regional* region, struct compress_tree_node* closest,
208 struct compress_tree_node** insertpt)
211 struct compress_tree_node* newnode;
212 struct compress_tree_node* prevnode = NULL;
213 int uplabs = labs-1; /* does not store root in tree */
214 if(closest) uplabs = labs - closest->labs;
215 log_assert(uplabs >= 0);
216 /* algorithms builds up a vine of dname-labels to hang into tree */
218 if(offset > PTR_MAX_OFFSET) {
219 /* insertion failed, drop vine */
220 return 1; /* compression pointer no longer useful */
222 if(!(newnode = compress_tree_newnode(dname, labs, offset,
224 /* insertion failed, drop vine */
229 /* chain nodes together, last one has one label more,
230 * so is larger than newnode, thus goes right. */
231 newnode->right = prevnode;
232 prevnode->parent = newnode;
242 /* if we have a vine, hang the vine into the tree */
244 *insertpt = prevnode;
245 prevnode->parent = closest;
250 /** compress a domain name */
252 write_compressed_dname(sldns_buffer* pkt, uint8_t* dname, int labs,
253 struct compress_tree_node* p)
256 int labcopy = labs - p->labs;
261 /* write root label */
262 if(sldns_buffer_remaining(pkt) < 1)
264 sldns_buffer_write_u8(pkt, 0);
268 /* copy the first couple of labels */
271 if(sldns_buffer_remaining(pkt) < (size_t)lablen+1)
273 sldns_buffer_write_u8(pkt, lablen);
274 sldns_buffer_write(pkt, dname, lablen);
277 /* insert compression ptr */
278 if(sldns_buffer_remaining(pkt) < 2)
280 ptr = PTR_CREATE(p->offset);
281 sldns_buffer_write_u16(pkt, ptr);
285 /** compress owner name of RR, return RETVAL_OUTMEM RETVAL_TRUNC */
287 compress_owner(struct ub_packed_rrset_key* key, sldns_buffer* pkt,
288 struct regional* region, struct compress_tree_node** tree,
289 size_t owner_pos, uint16_t* owner_ptr, int owner_labs)
291 struct compress_tree_node* p;
292 struct compress_tree_node** insertpt = NULL;
294 /* compress first time dname */
295 if((p = compress_tree_lookup(tree, key->rk.dname,
296 owner_labs, &insertpt))) {
297 if(p->labs == owner_labs)
298 /* avoid ptr chains, since some software is
299 * not capable of decoding ptr after a ptr. */
300 *owner_ptr = htons(PTR_CREATE(p->offset));
301 if(!write_compressed_dname(pkt, key->rk.dname,
304 /* check if typeclass+4 ttl + rdatalen is available */
305 if(sldns_buffer_remaining(pkt) < 4+4+2)
309 if(sldns_buffer_remaining(pkt) < key->rk.dname_len+4+4+2)
311 sldns_buffer_write(pkt, key->rk.dname,
313 if(owner_pos <= PTR_MAX_OFFSET)
314 *owner_ptr = htons(PTR_CREATE(owner_pos));
316 if(!compress_tree_store(key->rk.dname, owner_labs,
317 owner_pos, region, p, insertpt))
318 return RETVAL_OUTMEM;
320 /* always compress 2nd-further RRs in RRset */
321 if(owner_labs == 1) {
322 if(sldns_buffer_remaining(pkt) < 1+4+4+2)
324 sldns_buffer_write_u8(pkt, 0);
326 if(sldns_buffer_remaining(pkt) < 2+4+4+2)
328 sldns_buffer_write(pkt, owner_ptr, 2);
334 /** compress any domain name to the packet, return RETVAL_* */
336 compress_any_dname(uint8_t* dname, sldns_buffer* pkt, int labs,
337 struct regional* region, struct compress_tree_node** tree)
339 struct compress_tree_node* p;
340 struct compress_tree_node** insertpt = NULL;
341 size_t pos = sldns_buffer_position(pkt);
342 if((p = compress_tree_lookup(tree, dname, labs, &insertpt))) {
343 if(!write_compressed_dname(pkt, dname, labs, p))
346 if(!dname_buffer_write(pkt, dname))
349 if(!compress_tree_store(dname, labs, pos, region, p, insertpt))
350 return RETVAL_OUTMEM;
354 /** return true if type needs domain name compression in rdata */
355 static const sldns_rr_descriptor*
356 type_rdata_compressable(struct ub_packed_rrset_key* key)
358 uint16_t t = ntohs(key->rk.type);
359 if(sldns_rr_descript(t) &&
360 sldns_rr_descript(t)->_compress == LDNS_RR_COMPRESS)
361 return sldns_rr_descript(t);
365 /** compress domain names in rdata, return RETVAL_* */
367 compress_rdata(sldns_buffer* pkt, uint8_t* rdata, size_t todolen,
368 struct regional* region, struct compress_tree_node** tree,
369 const sldns_rr_descriptor* desc)
371 int labs, r, rdf = 0;
372 size_t dname_len, len, pos = sldns_buffer_position(pkt);
373 uint8_t count = desc->_dname_count;
375 sldns_buffer_skip(pkt, 2); /* rdata len fill in later */
376 /* space for rdatalen checked for already */
379 while(todolen > 0 && count) {
380 switch(desc->_wireformat[rdf]) {
381 case LDNS_RDF_TYPE_DNAME:
382 labs = dname_count_size_labels(rdata, &dname_len);
383 if((r=compress_any_dname(rdata, pkt, labs, region,
387 todolen -= dname_len;
391 case LDNS_RDF_TYPE_STR:
395 len = get_rdf_size(desc->_wireformat[rdf]);
399 if(sldns_buffer_remaining(pkt) < len)
401 sldns_buffer_write(pkt, rdata, len);
409 if(sldns_buffer_remaining(pkt) < todolen)
411 sldns_buffer_write(pkt, rdata, todolen);
415 sldns_buffer_write_u16_at(pkt, pos, sldns_buffer_position(pkt)-pos-2);
419 /** Returns true if RR type should be included */
421 rrset_belongs_in_reply(sldns_pkt_section s, uint16_t rrtype, uint16_t qtype,
426 /* skip non DNSSEC types, except if directly queried for */
427 if(s == LDNS_SECTION_ANSWER) {
428 if(qtype == LDNS_RR_TYPE_ANY || qtype == rrtype)
431 /* check DNSSEC-ness */
433 case LDNS_RR_TYPE_SIG:
434 case LDNS_RR_TYPE_KEY:
435 case LDNS_RR_TYPE_NXT:
436 case LDNS_RR_TYPE_DS:
437 case LDNS_RR_TYPE_RRSIG:
438 case LDNS_RR_TYPE_NSEC:
439 case LDNS_RR_TYPE_DNSKEY:
440 case LDNS_RR_TYPE_NSEC3:
441 case LDNS_RR_TYPE_NSEC3PARAMS:
447 /** store rrset in buffer in wireformat, return RETVAL_* */
449 packed_rrset_encode(struct ub_packed_rrset_key* key, sldns_buffer* pkt,
450 uint16_t* num_rrs, time_t timenow, struct regional* region,
451 int do_data, int do_sig, struct compress_tree_node** tree,
452 sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset)
454 size_t i, j, owner_pos;
456 uint16_t owner_ptr = 0;
457 struct packed_rrset_data* data = (struct packed_rrset_data*)
460 /* does this RR type belong in the answer? */
461 if(!rrset_belongs_in_reply(s, ntohs(key->rk.type), qtype, dnssec))
464 owner_labs = dname_count_labels(key->rk.dname);
465 owner_pos = sldns_buffer_position(pkt);
467 /* For an rrset with a fixed TTL, use the rrset's TTL as given */
468 if((key->rk.flags & PACKED_RRSET_FIXEDTTL) != 0)
472 const sldns_rr_descriptor* c = type_rdata_compressable(key);
473 for(i=0; i<data->count; i++) {
474 /* rrset roundrobin */
475 j = (i + rr_offset) % data->count;
476 if((r=compress_owner(key, pkt, region, tree,
477 owner_pos, &owner_ptr, owner_labs))
480 sldns_buffer_write(pkt, &key->rk.type, 2);
481 sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
482 if(data->rr_ttl[j] < timenow)
483 sldns_buffer_write_u32(pkt,
484 SERVE_EXPIRED?SERVE_EXPIRED_REPLY_TTL:0);
485 else sldns_buffer_write_u32(pkt,
486 data->rr_ttl[j]-timenow);
488 if((r=compress_rdata(pkt, data->rr_data[j],
489 data->rr_len[j], region, tree, c))
493 if(sldns_buffer_remaining(pkt) < data->rr_len[j])
495 sldns_buffer_write(pkt, data->rr_data[j],
501 if(do_sig && dnssec) {
502 size_t total = data->count+data->rrsig_count;
503 for(i=data->count; i<total; i++) {
504 if(owner_ptr && owner_labs != 1) {
505 if(sldns_buffer_remaining(pkt) <
506 2+4+4+data->rr_len[i])
508 sldns_buffer_write(pkt, &owner_ptr, 2);
510 if((r=compress_any_dname(key->rk.dname,
511 pkt, owner_labs, region, tree))
514 if(sldns_buffer_remaining(pkt) <
518 sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_RRSIG);
519 sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
520 if(data->rr_ttl[i] < timenow)
521 sldns_buffer_write_u32(pkt,
522 SERVE_EXPIRED?SERVE_EXPIRED_REPLY_TTL:0);
523 else sldns_buffer_write_u32(pkt,
524 data->rr_ttl[i]-timenow);
525 /* rrsig rdata cannot be compressed, perform 100+ byte
527 sldns_buffer_write(pkt, data->rr_data[i],
531 /* change rrnum only after we are sure it fits */
533 *num_rrs += data->count;
535 *num_rrs += data->rrsig_count;
540 /** store msg section in wireformat buffer, return RETVAL_* */
542 insert_section(struct reply_info* rep, size_t num_rrsets, uint16_t* num_rrs,
543 sldns_buffer* pkt, size_t rrsets_before, time_t timenow,
544 struct regional* region, struct compress_tree_node** tree,
545 sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset)
549 /* we now allow this function to be called multiple times for the
550 * same section, incrementally updating num_rrs. The caller is
551 * responsible for initializing it (which is the case in the current
552 * implementation). */
554 if(s != LDNS_SECTION_ADDITIONAL) {
555 if(s == LDNS_SECTION_ANSWER && qtype == LDNS_RR_TYPE_ANY)
556 dnssec = 1; /* include all types in ANY answer */
557 for(i=0; i<num_rrsets; i++) {
558 setstart = sldns_buffer_position(pkt);
559 if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
560 pkt, num_rrs, timenow, region, 1, 1, tree,
561 s, qtype, dnssec, rr_offset))
563 /* Bad, but if due to size must set TC bit */
564 /* trim off the rrset neatly. */
565 sldns_buffer_set_position(pkt, setstart);
570 for(i=0; i<num_rrsets; i++) {
571 setstart = sldns_buffer_position(pkt);
572 if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
573 pkt, num_rrs, timenow, region, 1, 0, tree,
574 s, qtype, dnssec, rr_offset))
576 sldns_buffer_set_position(pkt, setstart);
581 for(i=0; i<num_rrsets; i++) {
582 setstart = sldns_buffer_position(pkt);
583 if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
584 pkt, num_rrs, timenow, region, 0, 1, tree,
585 s, qtype, dnssec, rr_offset))
587 sldns_buffer_set_position(pkt, setstart);
595 /** store query section in wireformat buffer, return RETVAL */
597 insert_query(struct query_info* qinfo, struct compress_tree_node** tree,
598 sldns_buffer* buffer, struct regional* region)
600 uint8_t* qname = qinfo->local_alias ?
601 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
602 size_t qname_len = qinfo->local_alias ?
603 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len;
604 if(sldns_buffer_remaining(buffer) <
605 qinfo->qname_len+sizeof(uint16_t)*2)
606 return RETVAL_TRUNC; /* buffer too small */
607 /* the query is the first name inserted into the tree */
608 if(!compress_tree_store(qname, dname_count_labels(qname),
609 sldns_buffer_position(buffer), region, NULL, tree))
610 return RETVAL_OUTMEM;
611 if(sldns_buffer_current(buffer) == qname)
612 sldns_buffer_skip(buffer, (ssize_t)qname_len);
613 else sldns_buffer_write(buffer, qname, qname_len);
614 sldns_buffer_write_u16(buffer, qinfo->qtype);
615 sldns_buffer_write_u16(buffer, qinfo->qclass);
620 positive_answer(struct reply_info* rep, uint16_t qtype) {
622 if (FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR)
625 for(i=0;i<rep->an_numrrsets; i++) {
626 if(ntohs(rep->rrsets[i]->rk.type) == qtype) {
627 /* for priming queries, type NS, include addresses */
628 if(qtype == LDNS_RR_TYPE_NS)
630 /* in case it is a wildcard with DNSSEC, there will
631 * be NSEC/NSEC3 records in the authority section
632 * that we cannot remove */
633 for(i=rep->an_numrrsets; i<rep->an_numrrsets+
634 rep->ns_numrrsets; i++) {
635 if(ntohs(rep->rrsets[i]->rk.type) ==
637 ntohs(rep->rrsets[i]->rk.type) ==
648 negative_answer(struct reply_info* rep) {
651 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)
653 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR &&
654 rep->an_numrrsets != 0)
655 return 0; /* positive */
656 if(FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR &&
657 FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NXDOMAIN)
659 for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++){
660 if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_SOA)
662 if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NS)
665 if(ns_seen) return 0; /* could be referral, NS, but no SOA */
670 reply_info_encode(struct query_info* qinfo, struct reply_info* rep,
671 uint16_t id, uint16_t flags, sldns_buffer* buffer, time_t timenow,
672 struct regional* region, uint16_t udpsize, int dnssec, int minimise)
674 uint16_t ancount=0, nscount=0, arcount=0;
675 struct compress_tree_node* tree = 0;
679 sldns_buffer_clear(buffer);
680 if(udpsize < sldns_buffer_limit(buffer))
681 sldns_buffer_set_limit(buffer, udpsize);
682 if(sldns_buffer_remaining(buffer) < LDNS_HEADER_SIZE)
685 sldns_buffer_write(buffer, &id, sizeof(uint16_t));
686 sldns_buffer_write_u16(buffer, flags);
687 sldns_buffer_write_u16(buffer, rep->qdcount);
688 /* set an, ns, ar counts to zero in case of small packets */
689 sldns_buffer_write(buffer, "\000\000\000\000\000\000", 6);
691 /* insert query section */
693 if((r=insert_query(qinfo, &tree, buffer, region)) !=
695 if(r == RETVAL_TRUNC) {
696 /* create truncated message */
697 sldns_buffer_write_u16_at(buffer, 4, 0);
698 LDNS_TC_SET(sldns_buffer_begin(buffer));
699 sldns_buffer_flip(buffer);
705 /* roundrobin offset. using query id for random number. With ntohs
706 * for different roundrobins for sequential id client senders. */
707 rr_offset = RRSET_ROUNDROBIN?ntohs(id)+(timenow?timenow:time(NULL)):0;
709 /* "prepend" any local alias records in the answer section if this
710 * response is supposed to be authoritative. Currently it should
711 * be a single CNAME record (sanity-checked in worker_handle_request())
712 * but it can be extended if and when we support more variations of
714 if(qinfo->local_alias && (flags & BIT_AA)) {
715 struct reply_info arep;
716 time_t timezero = 0; /* to use the 'authoritative' TTL */
717 memset(&arep, 0, sizeof(arep));
718 arep.flags = rep->flags;
719 arep.an_numrrsets = 1;
720 arep.rrset_count = 1;
721 arep.rrsets = &qinfo->local_alias->rrset;
722 if((r=insert_section(&arep, 1, &ancount, buffer, 0,
723 timezero, region, &tree, LDNS_SECTION_ANSWER,
724 qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) {
725 if(r == RETVAL_TRUNC) {
726 /* create truncated message */
727 sldns_buffer_write_u16_at(buffer, 6, ancount);
728 LDNS_TC_SET(sldns_buffer_begin(buffer));
729 sldns_buffer_flip(buffer);
736 /* insert answer section */
737 if((r=insert_section(rep, rep->an_numrrsets, &ancount, buffer,
738 0, timenow, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype,
739 dnssec, rr_offset)) != RETVAL_OK) {
740 if(r == RETVAL_TRUNC) {
741 /* create truncated message */
742 sldns_buffer_write_u16_at(buffer, 6, ancount);
743 LDNS_TC_SET(sldns_buffer_begin(buffer));
744 sldns_buffer_flip(buffer);
749 sldns_buffer_write_u16_at(buffer, 6, ancount);
751 /* if response is positive answer, auth/add sections are not required */
752 if( ! (minimise && positive_answer(rep, qinfo->qtype)) ) {
753 /* insert auth section */
754 if((r=insert_section(rep, rep->ns_numrrsets, &nscount, buffer,
755 rep->an_numrrsets, timenow, region, &tree,
756 LDNS_SECTION_AUTHORITY, qinfo->qtype,
757 dnssec, rr_offset)) != RETVAL_OK) {
758 if(r == RETVAL_TRUNC) {
759 /* create truncated message */
760 sldns_buffer_write_u16_at(buffer, 8, nscount);
761 LDNS_TC_SET(sldns_buffer_begin(buffer));
762 sldns_buffer_flip(buffer);
767 sldns_buffer_write_u16_at(buffer, 8, nscount);
769 if(! (minimise && negative_answer(rep))) {
770 /* insert add section */
771 if((r=insert_section(rep, rep->ar_numrrsets, &arcount, buffer,
772 rep->an_numrrsets + rep->ns_numrrsets, timenow, region,
773 &tree, LDNS_SECTION_ADDITIONAL, qinfo->qtype,
774 dnssec, rr_offset)) != RETVAL_OK) {
775 if(r == RETVAL_TRUNC) {
776 /* no need to set TC bit, this is the additional */
777 sldns_buffer_write_u16_at(buffer, 10, arcount);
778 sldns_buffer_flip(buffer);
783 sldns_buffer_write_u16_at(buffer, 10, arcount);
786 sldns_buffer_flip(buffer);
791 calc_edns_field_size(struct edns_data* edns)
794 struct edns_option* opt;
795 if(!edns || !edns->edns_present)
797 for(opt = edns->opt_list; opt; opt = opt->next) {
798 rdatalen += 4 + opt->opt_len;
800 /* domain root '.' + type + class + ttl + rdatalen */
801 return 1 + 2 + 2 + 4 + 2 + rdatalen;
805 attach_edns_record(sldns_buffer* pkt, struct edns_data* edns)
809 struct edns_option* opt;
810 if(!edns || !edns->edns_present)
812 /* inc additional count */
813 sldns_buffer_write_u16_at(pkt, 10,
814 sldns_buffer_read_u16_at(pkt, 10) + 1);
815 len = sldns_buffer_limit(pkt);
816 sldns_buffer_clear(pkt);
817 sldns_buffer_set_position(pkt, len);
818 /* write EDNS record */
819 sldns_buffer_write_u8(pkt, 0); /* '.' label */
820 sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_OPT); /* type */
821 sldns_buffer_write_u16(pkt, edns->udp_size); /* class */
822 sldns_buffer_write_u8(pkt, edns->ext_rcode); /* ttl */
823 sldns_buffer_write_u8(pkt, edns->edns_version);
824 sldns_buffer_write_u16(pkt, edns->bits);
825 rdatapos = sldns_buffer_position(pkt);
826 sldns_buffer_write_u16(pkt, 0); /* rdatalen */
828 for(opt=edns->opt_list; opt; opt=opt->next) {
829 sldns_buffer_write_u16(pkt, opt->opt_code);
830 sldns_buffer_write_u16(pkt, opt->opt_len);
831 if(opt->opt_len != 0)
832 sldns_buffer_write(pkt, opt->opt_data, opt->opt_len);
835 sldns_buffer_write_u16_at(pkt, rdatapos,
836 sldns_buffer_position(pkt)-rdatapos-2);
837 sldns_buffer_flip(pkt);
841 reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep,
842 uint16_t id, uint16_t qflags, sldns_buffer* pkt, time_t timenow,
843 int cached, struct regional* region, uint16_t udpsize,
844 struct edns_data* edns, int dnssec, int secure)
847 unsigned int attach_edns = 0;
849 if(!cached || rep->authoritative) {
850 /* original flags, copy RD and CD bits from query. */
851 flags = rep->flags | (qflags & (BIT_RD|BIT_CD));
853 /* remove AA bit, copy RD and CD bits from query. */
854 flags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD));
856 if(secure && (dnssec || (qflags&BIT_AD)))
858 /* restore AA bit if we have a local alias and the response can be
859 * authoritative. Also clear AD bit if set as the local data is the
861 if(qinf->local_alias &&
862 (FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR ||
863 FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)) {
867 log_assert(flags & BIT_QR); /* QR bit must be on in our replies */
868 if(udpsize < LDNS_HEADER_SIZE)
870 if(sldns_buffer_capacity(pkt) < udpsize)
871 udpsize = sldns_buffer_capacity(pkt);
872 if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) {
873 /* packet too small to contain edns, omit it. */
876 /* reserve space for edns record */
877 attach_edns = (unsigned int)calc_edns_field_size(edns);
878 udpsize -= attach_edns;
881 if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region,
882 udpsize, dnssec, MINIMAL_RESPONSES)) {
883 log_err("reply encode: out of memory");
886 if(attach_edns && sldns_buffer_capacity(pkt) >=
887 sldns_buffer_limit(pkt)+attach_edns)
888 attach_edns_record(pkt, edns);
893 qinfo_query_encode(sldns_buffer* pkt, struct query_info* qinfo)
895 uint16_t flags = 0; /* QUERY, NOERROR */
896 const uint8_t* qname = qinfo->local_alias ?
897 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
898 size_t qname_len = qinfo->local_alias ?
899 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len;
900 sldns_buffer_clear(pkt);
901 log_assert(sldns_buffer_remaining(pkt) >= 12+255+4/*max query*/);
902 sldns_buffer_skip(pkt, 2); /* id done later */
903 sldns_buffer_write_u16(pkt, flags);
904 sldns_buffer_write_u16(pkt, 1); /* query count */
905 sldns_buffer_write(pkt, "\000\000\000\000\000\000", 6); /* counts */
906 sldns_buffer_write(pkt, qname, qname_len);
907 sldns_buffer_write_u16(pkt, qinfo->qtype);
908 sldns_buffer_write_u16(pkt, qinfo->qclass);
909 sldns_buffer_flip(pkt);
913 error_encode(sldns_buffer* buf, int r, struct query_info* qinfo,
914 uint16_t qid, uint16_t qflags, struct edns_data* edns)
918 sldns_buffer_clear(buf);
919 sldns_buffer_write(buf, &qid, sizeof(uint16_t));
920 flags = (uint16_t)(BIT_QR | BIT_RA | r); /* QR and retcode*/
921 flags |= (qflags & (BIT_RD|BIT_CD)); /* copy RD and CD bit */
922 sldns_buffer_write_u16(buf, flags);
925 sldns_buffer_write_u16(buf, flags);
927 sldns_buffer_write(buf, &flags, sizeof(uint16_t));
928 sldns_buffer_write(buf, &flags, sizeof(uint16_t));
929 sldns_buffer_write(buf, &flags, sizeof(uint16_t));
931 const uint8_t* qname = qinfo->local_alias ?
932 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
933 size_t qname_len = qinfo->local_alias ?
934 qinfo->local_alias->rrset->rk.dname_len :
936 if(sldns_buffer_current(buf) == qname)
937 sldns_buffer_skip(buf, (ssize_t)qname_len);
938 else sldns_buffer_write(buf, qname, qname_len);
939 sldns_buffer_write_u16(buf, qinfo->qtype);
940 sldns_buffer_write_u16(buf, qinfo->qclass);
942 sldns_buffer_flip(buf);
944 struct edns_data es = *edns;
945 es.edns_version = EDNS_ADVERTISED_VERSION;
946 es.udp_size = EDNS_ADVERTISED_SIZE;
949 if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
952 attach_edns_record(buf, &es);