contrib/unbound/util/data/msgencode.c

   1 /*
   2  * util/data/msgencode.c - Encode DNS messages, queries and replies.
   3  *
   4  * Copyright (c) 2007, NLnet Labs. All rights reserved.
   5  *
   6  * This software is open source.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * Redistributions of source code must retain the above copyright notice,
  13  * this list of conditions and the following disclaimer.
  14  *
  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.
  18  *
  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.
  22  *
  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.
  34  */
  35
  36 /**
  37  * \file
  38  *
  39  * This file contains a routines to encode DNS messages.
  40  */
  41
  42 #include "config.h"
  43 #include "util/data/msgencode.h"
  44 #include "util/data/msgreply.h"
  45 #include "util/data/msgparse.h"
  46 #include "util/data/dname.h"
  47 #include "util/log.h"
  48 #include "util/regional.h"
  49 #include "util/net_help.h"
  50 #include "sldns/sbuffer.h"
  51 #include "services/localzone.h"
  52
  53 #ifdef HAVE_TIME_H
  54 #include <time.h>
  55 #endif
  56 #include <sys/time.h>
  57
  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 */
  64 #define RETVAL_OK       0
  65
  66 /**
  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.
  72  *
  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
  75  * DNS packet size).
  76  */
  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;
  82
  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. */
  86         uint8_t* dname;
  87         /** number of labels in domain name, kept to help compare func. */
  88         int labs;
  89         /** offset in packet that points to this dname */
  90         size_t offset;
  91 };
  92
  93 /**
  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.
 105  */
 106 static int
 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)
 110 {
 111         int c, n, closen=0;
 112         struct compress_tree_node* p = *tree;
 113         struct compress_tree_node* close = 0;
 114         struct compress_tree_node** prev = tree;
 115         while(p) {
 116                 if((c = dname_lab_cmp(dname, labs, p->dname, p->labs, &n))
 117                         == 0) {
 118                         *matchlabels = n;
 119                         *match = p;
 120                         return 1;
 121                 }
 122                 if(c<0) {
 123                         prev = &p->left;
 124                         p = p->left;
 125                 } else  {
 126                         closen = n;
 127                         close = p; /* p->dname is smaller than dname */
 128                         prev = &p->right;
 129                         p = p->right;
 130                 }
 131         }
 132         *insertpt = prev;
 133         *matchlabels = closen;
 134         *match = close;
 135         return 0;
 136 }
 137
 138 /**
 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.
 145  */
 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)
 149 {
 150         struct compress_tree_node* p;
 151         int m;
 152         if(labs <= 1)
 153                 return 0; /* do not compress root node */
 154         if(compress_tree_search(tree, dname, labs, &p, &m, insertpt)) {
 155                 /* exact match */
 156                 return p;
 157         }
 158         /* return some ancestor of p that compresses well. */
 159         if(m>1) {
 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)
 163                         p = p->parent;
 164                 return p;
 165         }
 166         return 0;
 167 }
 168
 169 /**
 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.
 176  */
 177 static struct compress_tree_node*
 178 compress_tree_newnode(uint8_t* dname, int labs, size_t offset,
 179         struct regional* region)
 180 {
 181         struct compress_tree_node* n = (struct compress_tree_node*)
 182                 regional_alloc(region, sizeof(struct compress_tree_node));
 183         if(!n) return 0;
 184         n->left = 0;
 185         n->right = 0;
 186         n->parent = 0;
 187         n->dname = dname;
 188         n->labs = labs;
 189         n->offset = offset;
 190         return n;
 191 }
 192
 193 /**
 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.
 204  */
 205 static int
 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)
 209 {
 210         uint8_t lablen;
 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 */
 217         while(uplabs--) {
 218                 if(offset > PTR_MAX_OFFSET) {
 219                         /* insertion failed, drop vine */
 220                         return 1; /* compression pointer no longer useful */
 221                 }
 222                 if(!(newnode = compress_tree_newnode(dname, labs, offset,
 223                         region))) {
 224                         /* insertion failed, drop vine */
 225                         return 0;
 226                 }
 227
 228                 if(prevnode) {
 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;
 233                 }
 234
 235                 /* next label */
 236                 lablen = *dname++;
 237                 dname += lablen;
 238                 offset += lablen+1;
 239                 prevnode = newnode;
 240                 labs--;
 241         }
 242         /* if we have a vine, hang the vine into the tree */
 243         if(prevnode) {
 244                 *insertpt = prevnode;
 245                 prevnode->parent = closest;
 246         }
 247         return 1;
 248 }
 249
 250 /** compress a domain name */
 251 static int
 252 write_compressed_dname(sldns_buffer* pkt, uint8_t* dname, int labs,
 253         struct compress_tree_node* p)
 254 {
 255         /* compress it */
 256         int labcopy = labs - p->labs;
 257         uint8_t lablen;
 258         uint16_t ptr;
 259
 260         if(labs == 1) {
 261                 /* write root label */
 262                 if(sldns_buffer_remaining(pkt) < 1)
 263                         return 0;
 264                 sldns_buffer_write_u8(pkt, 0);
 265                 return 1;
 266         }
 267
 268         /* copy the first couple of labels */
 269         while(labcopy--) {
 270                 lablen = *dname++;
 271                 if(sldns_buffer_remaining(pkt) < (size_t)lablen+1)
 272                         return 0;
 273                 sldns_buffer_write_u8(pkt, lablen);
 274                 sldns_buffer_write(pkt, dname, lablen);
 275                 dname += lablen;
 276         }
 277         /* insert compression ptr */
 278         if(sldns_buffer_remaining(pkt) < 2)
 279                 return 0;
 280         ptr = PTR_CREATE(p->offset);
 281         sldns_buffer_write_u16(pkt, ptr);
 282         return 1;
 283 }
 284
 285 /** compress owner name of RR, return RETVAL_OUTMEM RETVAL_TRUNC */
 286 static int
 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)
 290 {
 291         struct compress_tree_node* p;
 292         struct compress_tree_node** insertpt = NULL;
 293         if(!*owner_ptr) {
 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,
 302                                 owner_labs, p))
 303                                 return RETVAL_TRUNC;
 304                         /* check if typeclass+4 ttl + rdatalen is available */
 305                         if(sldns_buffer_remaining(pkt) < 4+4+2)
 306                                 return RETVAL_TRUNC;
 307                 } else {
 308                         /* no compress */
 309                         if(sldns_buffer_remaining(pkt) < key->rk.dname_len+4+4+2)
 310                                 return RETVAL_TRUNC;
 311                         sldns_buffer_write(pkt, key->rk.dname,
 312                                 key->rk.dname_len);
 313                         if(owner_pos <= PTR_MAX_OFFSET)
 314                                 *owner_ptr = htons(PTR_CREATE(owner_pos));
 315                 }
 316                 if(!compress_tree_store(key->rk.dname, owner_labs,
 317                         owner_pos, region, p, insertpt))
 318                         return RETVAL_OUTMEM;
 319         } else {
 320                 /* always compress 2nd-further RRs in RRset */
 321                 if(owner_labs == 1) {
 322                         if(sldns_buffer_remaining(pkt) < 1+4+4+2)
 323                                 return RETVAL_TRUNC;
 324                         sldns_buffer_write_u8(pkt, 0);
 325                 } else {
 326                         if(sldns_buffer_remaining(pkt) < 2+4+4+2)
 327                                 return RETVAL_TRUNC;
 328                         sldns_buffer_write(pkt, owner_ptr, 2);
 329                 }
 330         }
 331         return RETVAL_OK;
 332 }
 333
 334 /** compress any domain name to the packet, return RETVAL_* */
 335 static int
 336 compress_any_dname(uint8_t* dname, sldns_buffer* pkt, int labs,
 337         struct regional* region, struct compress_tree_node** tree)
 338 {
 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))
 344                         return RETVAL_TRUNC;
 345         } else {
 346                 if(!dname_buffer_write(pkt, dname))
 347                         return RETVAL_TRUNC;
 348         }
 349         if(!compress_tree_store(dname, labs, pos, region, p, insertpt))
 350                 return RETVAL_OUTMEM;
 351         return RETVAL_OK;
 352 }
 353
 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)
 357 {
 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);
 362         return 0;
 363 }
 364
 365 /** compress domain names in rdata, return RETVAL_* */
 366 static int
 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)
 370 {
 371         int labs, r, rdf = 0;
 372         size_t dname_len, len, pos = sldns_buffer_position(pkt);
 373         uint8_t count = desc->_dname_count;
 374
 375         sldns_buffer_skip(pkt, 2); /* rdata len fill in later */
 376         /* space for rdatalen checked for already */
 377         rdata += 2;
 378         todolen -= 2;
 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,
 384                                 tree)) != RETVAL_OK)
 385                                 return r;
 386                         rdata += dname_len;
 387                         todolen -= dname_len;
 388                         count--;
 389                         len = 0;
 390                         break;
 391                 case LDNS_RDF_TYPE_STR:
 392                         len = *rdata + 1;
 393                         break;
 394                 default:
 395                         len = get_rdf_size(desc->_wireformat[rdf]);
 396                 }
 397                 if(len) {
 398                         /* copy over */
 399                         if(sldns_buffer_remaining(pkt) < len)
 400                                 return RETVAL_TRUNC;
 401                         sldns_buffer_write(pkt, rdata, len);
 402                         todolen -= len;
 403                         rdata += len;
 404                 }
 405                 rdf++;
 406         }
 407         /* copy remainder */
 408         if(todolen > 0) {
 409                 if(sldns_buffer_remaining(pkt) < todolen)
 410                         return RETVAL_TRUNC;
 411                 sldns_buffer_write(pkt, rdata, todolen);
 412         }
 413
 414         /* set rdata len */
 415         sldns_buffer_write_u16_at(pkt, pos, sldns_buffer_position(pkt)-pos-2);
 416         return RETVAL_OK;
 417 }
 418
 419 /** Returns true if RR type should be included */
 420 static int
 421 rrset_belongs_in_reply(sldns_pkt_section s, uint16_t rrtype, uint16_t qtype,
 422         int dnssec)
 423 {
 424         if(dnssec)
 425                 return 1;
 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)
 429                         return 1;
 430         }
 431         /* check DNSSEC-ness */
 432         switch(rrtype) {
 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:
 442                         return 0;
 443         }
 444         return 1;
 445 }
 446
 447 /** store rrset in buffer in wireformat, return RETVAL_* */
 448 static int
 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)
 453 {
 454         size_t i, j, owner_pos;
 455         int r, owner_labs;
 456         uint16_t owner_ptr = 0;
 457         struct packed_rrset_data* data = (struct packed_rrset_data*)
 458                 key->entry.data;
 459
 460         /* does this RR type belong in the answer? */
 461         if(!rrset_belongs_in_reply(s, ntohs(key->rk.type), qtype, dnssec))
 462                 return RETVAL_OK;
 463
 464         owner_labs = dname_count_labels(key->rk.dname);
 465         owner_pos = sldns_buffer_position(pkt);
 466
 467         /* For an rrset with a fixed TTL, use the rrset's TTL as given */
 468         if((key->rk.flags & PACKED_RRSET_FIXEDTTL) != 0)
 469                 timenow = 0;
 470
 471         if(do_data) {
 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))
 478                                 != RETVAL_OK)
 479                                 return r;
 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);
 487                         if(c) {
 488                                 if((r=compress_rdata(pkt, data->rr_data[j],
 489                                         data->rr_len[j], region, tree, c))
 490                                         != RETVAL_OK)
 491                                         return r;
 492                         } else {
 493                                 if(sldns_buffer_remaining(pkt) < data->rr_len[j])
 494                                         return RETVAL_TRUNC;
 495                                 sldns_buffer_write(pkt, data->rr_data[j],
 496                                         data->rr_len[j]);
 497                         }
 498                 }
 499         }
 500         /* insert rrsigs */
 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])
 507                                         return RETVAL_TRUNC;
 508                                 sldns_buffer_write(pkt, &owner_ptr, 2);
 509                         } else {
 510                                 if((r=compress_any_dname(key->rk.dname,
 511                                         pkt, owner_labs, region, tree))
 512                                         != RETVAL_OK)
 513                                         return r;
 514                                 if(sldns_buffer_remaining(pkt) <
 515                                         4+4+data->rr_len[i])
 516                                         return RETVAL_TRUNC;
 517                         }
 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
 526                          * memcopy. */
 527                         sldns_buffer_write(pkt, data->rr_data[i],
 528                                 data->rr_len[i]);
 529                 }
 530         }
 531         /* change rrnum only after we are sure it fits */
 532         if(do_data)
 533                 *num_rrs += data->count;
 534         if(do_sig && dnssec)
 535                 *num_rrs += data->rrsig_count;
 536
 537         return RETVAL_OK;
 538 }
 539
 540 /** store msg section in wireformat buffer, return RETVAL_* */
 541 static int
 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)
 546 {
 547         int r;
 548         size_t i, setstart;
 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). */
 553
 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))
 562                                 != RETVAL_OK) {
 563                                 /* Bad, but if due to size must set TC bit */
 564                                 /* trim off the rrset neatly. */
 565                                 sldns_buffer_set_position(pkt, setstart);
 566                                 return r;
 567                         }
 568                 }
 569         } else {
 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))
 575                                 != RETVAL_OK) {
 576                                 sldns_buffer_set_position(pkt, setstart);
 577                                 return r;
 578                         }
 579                 }
 580                 if(dnssec)
 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))
 586                                 != RETVAL_OK) {
 587                                 sldns_buffer_set_position(pkt, setstart);
 588                                 return r;
 589                         }
 590                   }
 591         }
 592         return RETVAL_OK;
 593 }
 594
 595 /** store query section in wireformat buffer, return RETVAL */
 596 static int
 597 insert_query(struct query_info* qinfo, struct compress_tree_node** tree,
 598         sldns_buffer* buffer, struct regional* region)
 599 {
 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);
 616         return RETVAL_OK;
 617 }
 618
 619 static int
 620 positive_answer(struct reply_info* rep, uint16_t qtype) {
 621         size_t i;
 622         if (FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR)
 623                 return 0;
 624
 625         for(i=0;i<rep->an_numrrsets; i++) {
 626                 if(ntohs(rep->rrsets[i]->rk.type) == qtype) {
 627                         /* in case it is a wildcard with DNSSEC, there will
 628                          * be NSEC/NSEC3 records in the authority section
 629                          * that we cannot remove */
 630                         for(i=rep->an_numrrsets; i<rep->an_numrrsets+
 631                                 rep->ns_numrrsets; i++) {
 632                                 if(ntohs(rep->rrsets[i]->rk.type) ==
 633                                         LDNS_RR_TYPE_NSEC ||
 634                                    ntohs(rep->rrsets[i]->rk.type) ==
 635                                         LDNS_RR_TYPE_NSEC3)
 636                                         return 0;
 637                         }
 638                         return 1;
 639                 }
 640         }
 641         return 0;
 642 }
 643
 644 static int
 645 negative_answer(struct reply_info* rep) {
 646         size_t i;
 647         int ns_seen = 0;
 648         if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)
 649                 return 1;
 650         if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR &&
 651                 rep->an_numrrsets != 0)
 652                 return 0; /* positive */
 653         if(FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR &&
 654                 FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NXDOMAIN)
 655                 return 0;
 656         for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++){
 657                 if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_SOA)
 658                         return 1;
 659                 if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NS)
 660                         ns_seen = 1;
 661         }
 662         if(ns_seen) return 0; /* could be referral, NS, but no SOA */
 663         return 1;
 664 }
 665
 666 int
 667 reply_info_encode(struct query_info* qinfo, struct reply_info* rep,
 668         uint16_t id, uint16_t flags, sldns_buffer* buffer, time_t timenow,
 669         struct regional* region, uint16_t udpsize, int dnssec, int minimise)
 670 {
 671         uint16_t ancount=0, nscount=0, arcount=0;
 672         struct compress_tree_node* tree = 0;
 673         int r;
 674         size_t rr_offset;
 675
 676         sldns_buffer_clear(buffer);
 677         if(udpsize < sldns_buffer_limit(buffer))
 678                 sldns_buffer_set_limit(buffer, udpsize);
 679         if(sldns_buffer_remaining(buffer) < LDNS_HEADER_SIZE)
 680                 return 0;
 681
 682         sldns_buffer_write(buffer, &id, sizeof(uint16_t));
 683         sldns_buffer_write_u16(buffer, flags);
 684         sldns_buffer_write_u16(buffer, rep->qdcount);
 685         /* set an, ns, ar counts to zero in case of small packets */
 686         sldns_buffer_write(buffer, "\000\000\000\000\000\000", 6);
 687
 688         /* insert query section */
 689         if(rep->qdcount) {
 690                 if((r=insert_query(qinfo, &tree, buffer, region)) !=
 691                         RETVAL_OK) {
 692                         if(r == RETVAL_TRUNC) {
 693                                 /* create truncated message */
 694                                 sldns_buffer_write_u16_at(buffer, 4, 0);
 695                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 696                                 sldns_buffer_flip(buffer);
 697                                 return 1;
 698                         }
 699                         return 0;
 700                 }
 701         }
 702         /* roundrobin offset. using query id for random number.  With ntohs
 703          * for different roundrobins for sequential id client senders. */
 704         rr_offset = RRSET_ROUNDROBIN?ntohs(id)+(timenow?timenow:time(NULL)):0;
 705
 706         /* "prepend" any local alias records in the answer section if this
 707          * response is supposed to be authoritative.  Currently it should
 708          * be a single CNAME record (sanity-checked in worker_handle_request())
 709          * but it can be extended if and when we support more variations of
 710          * aliases. */
 711         if(qinfo->local_alias && (flags & BIT_AA)) {
 712                 struct reply_info arep;
 713                 time_t timezero = 0; /* to use the 'authoritative' TTL */
 714                 memset(&arep, 0, sizeof(arep));
 715                 arep.flags = rep->flags;
 716                 arep.an_numrrsets = 1;
 717                 arep.rrset_count = 1;
 718                 arep.rrsets = &qinfo->local_alias->rrset;
 719                 if((r=insert_section(&arep, 1, &ancount, buffer, 0,
 720                         timezero, region, &tree, LDNS_SECTION_ANSWER,
 721                         qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) {
 722                         if(r == RETVAL_TRUNC) {
 723                                 /* create truncated message */
 724                                 sldns_buffer_write_u16_at(buffer, 6, ancount);
 725                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 726                                 sldns_buffer_flip(buffer);
 727                                 return 1;
 728                         }
 729                         return 0;
 730                 }
 731         }
 732
 733         /* insert answer section */
 734         if((r=insert_section(rep, rep->an_numrrsets, &ancount, buffer,
 735                 0, timenow, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype,
 736                 dnssec, rr_offset)) != RETVAL_OK) {
 737                 if(r == RETVAL_TRUNC) {
 738                         /* create truncated message */
 739                         sldns_buffer_write_u16_at(buffer, 6, ancount);
 740                         LDNS_TC_SET(sldns_buffer_begin(buffer));
 741                         sldns_buffer_flip(buffer);
 742                         return 1;
 743                 }
 744                 return 0;
 745         }
 746         sldns_buffer_write_u16_at(buffer, 6, ancount);
 747
 748         /* if response is positive answer, auth/add sections are not required */
 749         if( ! (minimise && positive_answer(rep, qinfo->qtype)) ) {
 750                 /* insert auth section */
 751                 if((r=insert_section(rep, rep->ns_numrrsets, &nscount, buffer,
 752                         rep->an_numrrsets, timenow, region, &tree,
 753                         LDNS_SECTION_AUTHORITY, qinfo->qtype,
 754                         dnssec, rr_offset)) != RETVAL_OK) {
 755                         if(r == RETVAL_TRUNC) {
 756                                 /* create truncated message */
 757                                 sldns_buffer_write_u16_at(buffer, 8, nscount);
 758                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 759                                 sldns_buffer_flip(buffer);
 760                                 return 1;
 761                         }
 762                         return 0;
 763                 }
 764                 sldns_buffer_write_u16_at(buffer, 8, nscount);
 765
 766                 if(! (minimise && negative_answer(rep))) {
 767                         /* insert add section */
 768                         if((r=insert_section(rep, rep->ar_numrrsets, &arcount, buffer,
 769                                 rep->an_numrrsets + rep->ns_numrrsets, timenow, region,
 770                                 &tree, LDNS_SECTION_ADDITIONAL, qinfo->qtype,
 771                                 dnssec, rr_offset)) != RETVAL_OK) {
 772                                 if(r == RETVAL_TRUNC) {
 773                                         /* no need to set TC bit, this is the additional */
 774                                         sldns_buffer_write_u16_at(buffer, 10, arcount);
 775                                         sldns_buffer_flip(buffer);
 776                                         return 1;
 777                                 }
 778                                 return 0;
 779                         }
 780                         sldns_buffer_write_u16_at(buffer, 10, arcount);
 781                 }
 782         }
 783         sldns_buffer_flip(buffer);
 784         return 1;
 785 }
 786
 787 uint16_t
 788 calc_edns_field_size(struct edns_data* edns)
 789 {
 790         size_t rdatalen = 0;
 791         struct edns_option* opt;
 792         if(!edns || !edns->edns_present)
 793                 return 0;
 794         for(opt = edns->opt_list; opt; opt = opt->next) {
 795                 rdatalen += 4 + opt->opt_len;
 796         }
 797         /* domain root '.' + type + class + ttl + rdatalen */
 798         return 1 + 2 + 2 + 4 + 2 + rdatalen;
 799 }
 800
 801 void
 802 attach_edns_record(sldns_buffer* pkt, struct edns_data* edns)
 803 {
 804         size_t len;
 805         size_t rdatapos;
 806         struct edns_option* opt;
 807         if(!edns || !edns->edns_present)
 808                 return;
 809         /* inc additional count */
 810         sldns_buffer_write_u16_at(pkt, 10,
 811                 sldns_buffer_read_u16_at(pkt, 10) + 1);
 812         len = sldns_buffer_limit(pkt);
 813         sldns_buffer_clear(pkt);
 814         sldns_buffer_set_position(pkt, len);
 815         /* write EDNS record */
 816         sldns_buffer_write_u8(pkt, 0); /* '.' label */
 817         sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_OPT); /* type */
 818         sldns_buffer_write_u16(pkt, edns->udp_size); /* class */
 819         sldns_buffer_write_u8(pkt, edns->ext_rcode); /* ttl */
 820         sldns_buffer_write_u8(pkt, edns->edns_version);
 821         sldns_buffer_write_u16(pkt, edns->bits);
 822         rdatapos = sldns_buffer_position(pkt);
 823         sldns_buffer_write_u16(pkt, 0); /* rdatalen */
 824         /* write rdata */
 825         for(opt=edns->opt_list; opt; opt=opt->next) {
 826                 sldns_buffer_write_u16(pkt, opt->opt_code);
 827                 sldns_buffer_write_u16(pkt, opt->opt_len);
 828                 if(opt->opt_len != 0)
 829                         sldns_buffer_write(pkt, opt->opt_data, opt->opt_len);
 830         }
 831         if(edns->opt_list)
 832                 sldns_buffer_write_u16_at(pkt, rdatapos,
 833                         sldns_buffer_position(pkt)-rdatapos-2);
 834         sldns_buffer_flip(pkt);
 835 }
 836
 837 int
 838 reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep,
 839         uint16_t id, uint16_t qflags, sldns_buffer* pkt, time_t timenow,
 840         int cached, struct regional* region, uint16_t udpsize,
 841         struct edns_data* edns, int dnssec, int secure)
 842 {
 843         uint16_t flags;
 844         unsigned int attach_edns = 0;
 845
 846         if(!cached || rep->authoritative) {
 847                 /* original flags, copy RD and CD bits from query. */
 848                 flags = rep->flags | (qflags & (BIT_RD|BIT_CD));
 849         } else {
 850                 /* remove AA bit, copy RD and CD bits from query. */
 851                 flags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD));
 852         }
 853         if(secure && (dnssec || (qflags&BIT_AD)))
 854                 flags |= BIT_AD;
 855         /* restore AA bit if we have a local alias and the response can be
 856          * authoritative.  Also clear AD bit if set as the local data is the
 857          * primary answer. */
 858         if(qinf->local_alias &&
 859                 (FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR ||
 860                 FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)) {
 861                 flags |= BIT_AA;
 862                 flags &= ~BIT_AD;
 863         }
 864         log_assert(flags & BIT_QR); /* QR bit must be on in our replies */
 865         if(udpsize < LDNS_HEADER_SIZE)
 866                 return 0;
 867         if(sldns_buffer_capacity(pkt) < udpsize)
 868                 udpsize = sldns_buffer_capacity(pkt);
 869         if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) {
 870                 /* packet too small to contain edns, omit it. */
 871                 attach_edns = 0;
 872         } else {
 873                 /* reserve space for edns record */
 874                 attach_edns = (unsigned int)calc_edns_field_size(edns);
 875                 udpsize -= attach_edns;
 876         }
 877
 878         if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region,
 879                 udpsize, dnssec, MINIMAL_RESPONSES)) {
 880                 log_err("reply encode: out of memory");
 881                 return 0;
 882         }
 883         if(attach_edns && sldns_buffer_capacity(pkt) >=
 884                 sldns_buffer_limit(pkt)+attach_edns)
 885                 attach_edns_record(pkt, edns);
 886         return 1;
 887 }
 888
 889 void
 890 qinfo_query_encode(sldns_buffer* pkt, struct query_info* qinfo)
 891 {
 892         uint16_t flags = 0; /* QUERY, NOERROR */
 893         const uint8_t* qname = qinfo->local_alias ?
 894                 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 895         size_t qname_len = qinfo->local_alias ?
 896                 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len;
 897         sldns_buffer_clear(pkt);
 898         log_assert(sldns_buffer_remaining(pkt) >= 12+255+4/*max query*/);
 899         sldns_buffer_skip(pkt, 2); /* id done later */
 900         sldns_buffer_write_u16(pkt, flags);
 901         sldns_buffer_write_u16(pkt, 1); /* query count */
 902         sldns_buffer_write(pkt, "\000\000\000\000\000\000", 6); /* counts */
 903         sldns_buffer_write(pkt, qname, qname_len);
 904         sldns_buffer_write_u16(pkt, qinfo->qtype);
 905         sldns_buffer_write_u16(pkt, qinfo->qclass);
 906         sldns_buffer_flip(pkt);
 907 }
 908
 909 void
 910 error_encode(sldns_buffer* buf, int r, struct query_info* qinfo,
 911         uint16_t qid, uint16_t qflags, struct edns_data* edns)
 912 {
 913         uint16_t flags;
 914
 915         sldns_buffer_clear(buf);
 916         sldns_buffer_write(buf, &qid, sizeof(uint16_t));
 917         flags = (uint16_t)(BIT_QR | BIT_RA | r); /* QR and retcode*/
 918         flags |= (qflags & (BIT_RD|BIT_CD)); /* copy RD and CD bit */
 919         sldns_buffer_write_u16(buf, flags);
 920         if(qinfo) flags = 1;
 921         else    flags = 0;
 922         sldns_buffer_write_u16(buf, flags);
 923         flags = 0;
 924         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 925         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 926         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 927         if(qinfo) {
 928                 const uint8_t* qname = qinfo->local_alias ?
 929                         qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 930                 size_t qname_len = qinfo->local_alias ?
 931                         qinfo->local_alias->rrset->rk.dname_len :
 932                         qinfo->qname_len;
 933                 if(sldns_buffer_current(buf) == qname)
 934                         sldns_buffer_skip(buf, (ssize_t)qname_len);
 935                 else    sldns_buffer_write(buf, qname, qname_len);
 936                 sldns_buffer_write_u16(buf, qinfo->qtype);
 937                 sldns_buffer_write_u16(buf, qinfo->qclass);
 938         }
 939         sldns_buffer_flip(buf);
 940         if(edns) {
 941                 struct edns_data es = *edns;
 942                 es.edns_version = EDNS_ADVERTISED_VERSION;
 943                 es.udp_size = EDNS_ADVERTISED_SIZE;
 944                 es.ext_rcode = 0;
 945                 es.bits &= EDNS_DO;
 946                 if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
 947                         edns->udp_size)
 948                         return;
 949                 attach_edns_record(buf, &es);
 950         }
 951 }