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 /** return code that means the function ran out of memory. negative so it does
  54  * not conflict with DNS rcodes. */
  55 #define RETVAL_OUTMEM   -2
  56 /** return code that means the data did not fit (completely) in the packet */
  57 #define RETVAL_TRUNC    -4
  58 /** return code that means all is peachy keen. Equal to DNS rcode NOERROR */
  59 #define RETVAL_OK       0
  60
  61 /**
  62  * Data structure to help domain name compression in outgoing messages.
  63  * A tree of dnames and their offsets in the packet is kept.
  64  * It is kept sorted, not canonical, but by label at least, so that after
  65  * a lookup of a name you know its closest match, and the parent from that
  66  * closest match. These are possible compression targets.
  67  *
  68  * It is a binary tree, not a rbtree or balanced tree, as the effort
  69  * of keeping it balanced probably outweighs usefulness (given typical
  70  * DNS packet size).
  71  */
  72 struct compress_tree_node {
  73         /** left node in tree, all smaller to this */
  74         struct compress_tree_node* left;
  75         /** right node in tree, all larger than this */
  76         struct compress_tree_node* right;
  77
  78         /** the parent node - not for tree, but zone parent. One less label */
  79         struct compress_tree_node* parent;
  80         /** the domain name for this node. Pointer to uncompressed memory. */
  81         uint8_t* dname;
  82         /** number of labels in domain name, kept to help compare func. */
  83         int labs;
  84         /** offset in packet that points to this dname */
  85         size_t offset;
  86 };
  87
  88 /**
  89  * Find domain name in tree, returns exact and closest match.
  90  * @param tree: root of tree.
  91  * @param dname: pointer to uncompressed dname.
  92  * @param labs: number of labels in domain name.
  93  * @param match: closest or exact match.
  94  *      guaranteed to be smaller or equal to the sought dname.
  95  *      can be null if the tree is empty.
  96  * @param matchlabels: number of labels that match with closest match.
  97  *      can be zero is there is no match.
  98  * @param insertpt: insert location for dname, if not found.
  99  * @return: 0 if no exact match.
 100  */
 101 static int
 102 compress_tree_search(struct compress_tree_node** tree, uint8_t* dname,
 103         int labs, struct compress_tree_node** match, int* matchlabels,
 104         struct compress_tree_node*** insertpt)
 105 {
 106         int c, n, closen=0;
 107         struct compress_tree_node* p = *tree;
 108         struct compress_tree_node* close = 0;
 109         struct compress_tree_node** prev = tree;
 110         while(p) {
 111                 if((c = dname_lab_cmp(dname, labs, p->dname, p->labs, &n))
 112                         == 0) {
 113                         *matchlabels = n;
 114                         *match = p;
 115                         return 1;
 116                 }
 117                 if(c<0) {
 118                         prev = &p->left;
 119                         p = p->left;
 120                 } else  {
 121                         closen = n;
 122                         close = p; /* p->dname is smaller than dname */
 123                         prev = &p->right;
 124                         p = p->right;
 125                 }
 126         }
 127         *insertpt = prev;
 128         *matchlabels = closen;
 129         *match = close;
 130         return 0;
 131 }
 132
 133 /**
 134  * Lookup a domain name in compression tree.
 135  * @param tree: root of tree (not the node with '.').
 136  * @param dname: pointer to uncompressed dname.
 137  * @param labs: number of labels in domain name.
 138  * @param insertpt: insert location for dname, if not found.
 139  * @return: 0 if not found or compress treenode with best compression.
 140  */
 141 static struct compress_tree_node*
 142 compress_tree_lookup(struct compress_tree_node** tree, uint8_t* dname,
 143         int labs, struct compress_tree_node*** insertpt)
 144 {
 145         struct compress_tree_node* p;
 146         int m;
 147         if(labs <= 1)
 148                 return 0; /* do not compress root node */
 149         if(compress_tree_search(tree, dname, labs, &p, &m, insertpt)) {
 150                 /* exact match */
 151                 return p;
 152         }
 153         /* return some ancestor of p that compresses well. */
 154         if(m>1) {
 155                 /* www.example.com. (labs=4) matched foo.example.com.(labs=4)
 156                  * then matchcount = 3. need to go up. */
 157                 while(p && p->labs > m)
 158                         p = p->parent;
 159                 return p;
 160         }
 161         return 0;
 162 }
 163
 164 /**
 165  * Create node for domain name compression tree.
 166  * @param dname: pointer to uncompressed dname (stored in tree).
 167  * @param labs: number of labels in dname.
 168  * @param offset: offset into packet for dname.
 169  * @param region: how to allocate memory for new node.
 170  * @return new node or 0 on malloc failure.
 171  */
 172 static struct compress_tree_node*
 173 compress_tree_newnode(uint8_t* dname, int labs, size_t offset,
 174         struct regional* region)
 175 {
 176         struct compress_tree_node* n = (struct compress_tree_node*)
 177                 regional_alloc(region, sizeof(struct compress_tree_node));
 178         if(!n) return 0;
 179         n->left = 0;
 180         n->right = 0;
 181         n->parent = 0;
 182         n->dname = dname;
 183         n->labs = labs;
 184         n->offset = offset;
 185         return n;
 186 }
 187
 188 /**
 189  * Store domain name and ancestors into compression tree.
 190  * @param dname: pointer to uncompressed dname (stored in tree).
 191  * @param labs: number of labels in dname.
 192  * @param offset: offset into packet for dname.
 193  * @param region: how to allocate memory for new node.
 194  * @param closest: match from previous lookup, used to compress dname.
 195  *      may be NULL if no previous match.
 196  *      if the tree has an ancestor of dname already, this must be it.
 197  * @param insertpt: where to insert the dname in tree.
 198  * @return: 0 on memory error.
 199  */
 200 static int
 201 compress_tree_store(uint8_t* dname, int labs, size_t offset,
 202         struct regional* region, struct compress_tree_node* closest,
 203         struct compress_tree_node** insertpt)
 204 {
 205         uint8_t lablen;
 206         struct compress_tree_node* newnode;
 207         struct compress_tree_node* prevnode = NULL;
 208         int uplabs = labs-1; /* does not store root in tree */
 209         if(closest) uplabs = labs - closest->labs;
 210         log_assert(uplabs >= 0);
 211         /* algorithms builds up a vine of dname-labels to hang into tree */
 212         while(uplabs--) {
 213                 if(offset > PTR_MAX_OFFSET) {
 214                         /* insertion failed, drop vine */
 215                         return 1; /* compression pointer no longer useful */
 216                 }
 217                 if(!(newnode = compress_tree_newnode(dname, labs, offset,
 218                         region))) {
 219                         /* insertion failed, drop vine */
 220                         return 0;
 221                 }
 222
 223                 if(prevnode) {
 224                         /* chain nodes together, last one has one label more,
 225                          * so is larger than newnode, thus goes right. */
 226                         newnode->right = prevnode;
 227                         prevnode->parent = newnode;
 228                 }
 229
 230                 /* next label */
 231                 lablen = *dname++;
 232                 dname += lablen;
 233                 offset += lablen+1;
 234                 prevnode = newnode;
 235                 labs--;
 236         }
 237         /* if we have a vine, hang the vine into the tree */
 238         if(prevnode) {
 239                 *insertpt = prevnode;
 240                 prevnode->parent = closest;
 241         }
 242         return 1;
 243 }
 244
 245 /** compress a domain name */
 246 static int
 247 write_compressed_dname(sldns_buffer* pkt, uint8_t* dname, int labs,
 248         struct compress_tree_node* p)
 249 {
 250         /* compress it */
 251         int labcopy = labs - p->labs;
 252         uint8_t lablen;
 253         uint16_t ptr;
 254
 255         if(labs == 1) {
 256                 /* write root label */
 257                 if(sldns_buffer_remaining(pkt) < 1)
 258                         return 0;
 259                 sldns_buffer_write_u8(pkt, 0);
 260                 return 1;
 261         }
 262
 263         /* copy the first couple of labels */
 264         while(labcopy--) {
 265                 lablen = *dname++;
 266                 if(sldns_buffer_remaining(pkt) < (size_t)lablen+1)
 267                         return 0;
 268                 sldns_buffer_write_u8(pkt, lablen);
 269                 sldns_buffer_write(pkt, dname, lablen);
 270                 dname += lablen;
 271         }
 272         /* insert compression ptr */
 273         if(sldns_buffer_remaining(pkt) < 2)
 274                 return 0;
 275         ptr = PTR_CREATE(p->offset);
 276         sldns_buffer_write_u16(pkt, ptr);
 277         return 1;
 278 }
 279
 280 /** compress owner name of RR, return RETVAL_OUTMEM RETVAL_TRUNC */
 281 static int
 282 compress_owner(struct ub_packed_rrset_key* key, sldns_buffer* pkt,
 283         struct regional* region, struct compress_tree_node** tree,
 284         size_t owner_pos, uint16_t* owner_ptr, int owner_labs)
 285 {
 286         struct compress_tree_node* p;
 287         struct compress_tree_node** insertpt = NULL;
 288         if(!*owner_ptr) {
 289                 /* compress first time dname */
 290                 if((p = compress_tree_lookup(tree, key->rk.dname,
 291                         owner_labs, &insertpt))) {
 292                         if(p->labs == owner_labs)
 293                                 /* avoid ptr chains, since some software is
 294                                  * not capable of decoding ptr after a ptr. */
 295                                 *owner_ptr = htons(PTR_CREATE(p->offset));
 296                         if(!write_compressed_dname(pkt, key->rk.dname,
 297                                 owner_labs, p))
 298                                 return RETVAL_TRUNC;
 299                         /* check if typeclass+4 ttl + rdatalen is available */
 300                         if(sldns_buffer_remaining(pkt) < 4+4+2)
 301                                 return RETVAL_TRUNC;
 302                 } else {
 303                         /* no compress */
 304                         if(sldns_buffer_remaining(pkt) < key->rk.dname_len+4+4+2)
 305                                 return RETVAL_TRUNC;
 306                         sldns_buffer_write(pkt, key->rk.dname,
 307                                 key->rk.dname_len);
 308                         if(owner_pos <= PTR_MAX_OFFSET)
 309                                 *owner_ptr = htons(PTR_CREATE(owner_pos));
 310                 }
 311                 if(!compress_tree_store(key->rk.dname, owner_labs,
 312                         owner_pos, region, p, insertpt))
 313                         return RETVAL_OUTMEM;
 314         } else {
 315                 /* always compress 2nd-further RRs in RRset */
 316                 if(owner_labs == 1) {
 317                         if(sldns_buffer_remaining(pkt) < 1+4+4+2)
 318                                 return RETVAL_TRUNC;
 319                         sldns_buffer_write_u8(pkt, 0);
 320                 } else {
 321                         if(sldns_buffer_remaining(pkt) < 2+4+4+2)
 322                                 return RETVAL_TRUNC;
 323                         sldns_buffer_write(pkt, owner_ptr, 2);
 324                 }
 325         }
 326         return RETVAL_OK;
 327 }
 328
 329 /** compress any domain name to the packet, return RETVAL_* */
 330 static int
 331 compress_any_dname(uint8_t* dname, sldns_buffer* pkt, int labs,
 332         struct regional* region, struct compress_tree_node** tree)
 333 {
 334         struct compress_tree_node* p;
 335         struct compress_tree_node** insertpt = NULL;
 336         size_t pos = sldns_buffer_position(pkt);
 337         if((p = compress_tree_lookup(tree, dname, labs, &insertpt))) {
 338                 if(!write_compressed_dname(pkt, dname, labs, p))
 339                         return RETVAL_TRUNC;
 340         } else {
 341                 if(!dname_buffer_write(pkt, dname))
 342                         return RETVAL_TRUNC;
 343         }
 344         if(!compress_tree_store(dname, labs, pos, region, p, insertpt))
 345                 return RETVAL_OUTMEM;
 346         return RETVAL_OK;
 347 }
 348
 349 /** return true if type needs domain name compression in rdata */
 350 static const sldns_rr_descriptor*
 351 type_rdata_compressable(struct ub_packed_rrset_key* key)
 352 {
 353         uint16_t t = ntohs(key->rk.type);
 354         if(sldns_rr_descript(t) &&
 355                 sldns_rr_descript(t)->_compress == LDNS_RR_COMPRESS)
 356                 return sldns_rr_descript(t);
 357         return 0;
 358 }
 359
 360 /** compress domain names in rdata, return RETVAL_* */
 361 static int
 362 compress_rdata(sldns_buffer* pkt, uint8_t* rdata, size_t todolen,
 363         struct regional* region, struct compress_tree_node** tree,
 364         const sldns_rr_descriptor* desc)
 365 {
 366         int labs, r, rdf = 0;
 367         size_t dname_len, len, pos = sldns_buffer_position(pkt);
 368         uint8_t count = desc->_dname_count;
 369
 370         sldns_buffer_skip(pkt, 2); /* rdata len fill in later */
 371         /* space for rdatalen checked for already */
 372         rdata += 2;
 373         todolen -= 2;
 374         while(todolen > 0 && count) {
 375                 switch(desc->_wireformat[rdf]) {
 376                 case LDNS_RDF_TYPE_DNAME:
 377                         labs = dname_count_size_labels(rdata, &dname_len);
 378                         if((r=compress_any_dname(rdata, pkt, labs, region,
 379                                 tree)) != RETVAL_OK)
 380                                 return r;
 381                         rdata += dname_len;
 382                         todolen -= dname_len;
 383                         count--;
 384                         len = 0;
 385                         break;
 386                 case LDNS_RDF_TYPE_STR:
 387                         len = *rdata + 1;
 388                         break;
 389                 default:
 390                         len = get_rdf_size(desc->_wireformat[rdf]);
 391                 }
 392                 if(len) {
 393                         /* copy over */
 394                         if(sldns_buffer_remaining(pkt) < len)
 395                                 return RETVAL_TRUNC;
 396                         sldns_buffer_write(pkt, rdata, len);
 397                         todolen -= len;
 398                         rdata += len;
 399                 }
 400                 rdf++;
 401         }
 402         /* copy remainder */
 403         if(todolen > 0) {
 404                 if(sldns_buffer_remaining(pkt) < todolen)
 405                         return RETVAL_TRUNC;
 406                 sldns_buffer_write(pkt, rdata, todolen);
 407         }
 408
 409         /* set rdata len */
 410         sldns_buffer_write_u16_at(pkt, pos, sldns_buffer_position(pkt)-pos-2);
 411         return RETVAL_OK;
 412 }
 413
 414 /** Returns true if RR type should be included */
 415 static int
 416 rrset_belongs_in_reply(sldns_pkt_section s, uint16_t rrtype, uint16_t qtype,
 417         int dnssec)
 418 {
 419         if(dnssec)
 420                 return 1;
 421         /* skip non DNSSEC types, except if directly queried for */
 422         if(s == LDNS_SECTION_ANSWER) {
 423                 if(qtype == LDNS_RR_TYPE_ANY || qtype == rrtype)
 424                         return 1;
 425         }
 426         /* check DNSSEC-ness */
 427         switch(rrtype) {
 428                 case LDNS_RR_TYPE_SIG:
 429                 case LDNS_RR_TYPE_KEY:
 430                 case LDNS_RR_TYPE_NXT:
 431                 case LDNS_RR_TYPE_DS:
 432                 case LDNS_RR_TYPE_RRSIG:
 433                 case LDNS_RR_TYPE_NSEC:
 434                 case LDNS_RR_TYPE_DNSKEY:
 435                 case LDNS_RR_TYPE_NSEC3:
 436                 case LDNS_RR_TYPE_NSEC3PARAMS:
 437                         return 0;
 438         }
 439         return 1;
 440 }
 441
 442 /** store rrset in buffer in wireformat, return RETVAL_* */
 443 static int
 444 packed_rrset_encode(struct ub_packed_rrset_key* key, sldns_buffer* pkt,
 445         uint16_t* num_rrs, time_t timenow, struct regional* region,
 446         int do_data, int do_sig, struct compress_tree_node** tree,
 447         sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset)
 448 {
 449         size_t i, j, owner_pos;
 450         int r, owner_labs;
 451         uint16_t owner_ptr = 0;
 452         struct packed_rrset_data* data = (struct packed_rrset_data*)
 453                 key->entry.data;
 454
 455         /* does this RR type belong in the answer? */
 456         if(!rrset_belongs_in_reply(s, ntohs(key->rk.type), qtype, dnssec))
 457                 return RETVAL_OK;
 458
 459         owner_labs = dname_count_labels(key->rk.dname);
 460         owner_pos = sldns_buffer_position(pkt);
 461
 462         if(do_data) {
 463                 const sldns_rr_descriptor* c = type_rdata_compressable(key);
 464                 for(i=0; i<data->count; i++) {
 465                         /* rrset roundrobin */
 466                         j = (i + rr_offset) % data->count;
 467                         if((r=compress_owner(key, pkt, region, tree,
 468                                 owner_pos, &owner_ptr, owner_labs))
 469                                 != RETVAL_OK)
 470                                 return r;
 471                         sldns_buffer_write(pkt, &key->rk.type, 2);
 472                         sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
 473                         if(data->rr_ttl[j] < timenow)
 474                                 sldns_buffer_write_u32(pkt, 0);
 475                         else    sldns_buffer_write_u32(pkt,
 476                                         data->rr_ttl[j]-timenow);
 477                         if(c) {
 478                                 if((r=compress_rdata(pkt, data->rr_data[j],
 479                                         data->rr_len[j], region, tree, c))
 480                                         != RETVAL_OK)
 481                                         return r;
 482                         } else {
 483                                 if(sldns_buffer_remaining(pkt) < data->rr_len[j])
 484                                         return RETVAL_TRUNC;
 485                                 sldns_buffer_write(pkt, data->rr_data[j],
 486                                         data->rr_len[j]);
 487                         }
 488                 }
 489         }
 490         /* insert rrsigs */
 491         if(do_sig && dnssec) {
 492                 size_t total = data->count+data->rrsig_count;
 493                 for(i=data->count; i<total; i++) {
 494                         if(owner_ptr && owner_labs != 1) {
 495                                 if(sldns_buffer_remaining(pkt) <
 496                                         2+4+4+data->rr_len[i])
 497                                         return RETVAL_TRUNC;
 498                                 sldns_buffer_write(pkt, &owner_ptr, 2);
 499                         } else {
 500                                 if((r=compress_any_dname(key->rk.dname,
 501                                         pkt, owner_labs, region, tree))
 502                                         != RETVAL_OK)
 503                                         return r;
 504                                 if(sldns_buffer_remaining(pkt) <
 505                                         4+4+data->rr_len[i])
 506                                         return RETVAL_TRUNC;
 507                         }
 508                         sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_RRSIG);
 509                         sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
 510                         if(data->rr_ttl[i] < timenow)
 511                                 sldns_buffer_write_u32(pkt, 0);
 512                         else    sldns_buffer_write_u32(pkt,
 513                                         data->rr_ttl[i]-timenow);
 514                         /* rrsig rdata cannot be compressed, perform 100+ byte
 515                          * memcopy. */
 516                         sldns_buffer_write(pkt, data->rr_data[i],
 517                                 data->rr_len[i]);
 518                 }
 519         }
 520         /* change rrnum only after we are sure it fits */
 521         if(do_data)
 522                 *num_rrs += data->count;
 523         if(do_sig && dnssec)
 524                 *num_rrs += data->rrsig_count;
 525
 526         return RETVAL_OK;
 527 }
 528
 529 /** store msg section in wireformat buffer, return RETVAL_* */
 530 static int
 531 insert_section(struct reply_info* rep, size_t num_rrsets, uint16_t* num_rrs,
 532         sldns_buffer* pkt, size_t rrsets_before, time_t timenow,
 533         struct regional* region, struct compress_tree_node** tree,
 534         sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset)
 535 {
 536         int r;
 537         size_t i, setstart;
 538         /* we now allow this function to be called multiple times for the
 539          * same section, incrementally updating num_rrs.  The caller is
 540          * responsible for initializing it (which is the case in the current
 541          * implementation). */
 542
 543         if(s != LDNS_SECTION_ADDITIONAL) {
 544                 if(s == LDNS_SECTION_ANSWER && qtype == LDNS_RR_TYPE_ANY)
 545                         dnssec = 1; /* include all types in ANY answer */
 546                 for(i=0; i<num_rrsets; i++) {
 547                         setstart = sldns_buffer_position(pkt);
 548                         if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
 549                                 pkt, num_rrs, timenow, region, 1, 1, tree,
 550                                 s, qtype, dnssec, rr_offset))
 551                                 != RETVAL_OK) {
 552                                 /* Bad, but if due to size must set TC bit */
 553                                 /* trim off the rrset neatly. */
 554                                 sldns_buffer_set_position(pkt, setstart);
 555                                 return r;
 556                         }
 557                 }
 558         } else {
 559                 for(i=0; i<num_rrsets; i++) {
 560                         setstart = sldns_buffer_position(pkt);
 561                         if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
 562                                 pkt, num_rrs, timenow, region, 1, 0, tree,
 563                                 s, qtype, dnssec, rr_offset))
 564                                 != RETVAL_OK) {
 565                                 sldns_buffer_set_position(pkt, setstart);
 566                                 return r;
 567                         }
 568                 }
 569                 if(dnssec)
 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, 0, 1, tree,
 574                                 s, qtype, dnssec, rr_offset))
 575                                 != RETVAL_OK) {
 576                                 sldns_buffer_set_position(pkt, setstart);
 577                                 return r;
 578                         }
 579                   }
 580         }
 581         return RETVAL_OK;
 582 }
 583
 584 /** store query section in wireformat buffer, return RETVAL */
 585 static int
 586 insert_query(struct query_info* qinfo, struct compress_tree_node** tree,
 587         sldns_buffer* buffer, struct regional* region)
 588 {
 589         uint8_t* qname = qinfo->local_alias ?
 590                 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 591         size_t qname_len = qinfo->local_alias ?
 592                 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len;
 593         if(sldns_buffer_remaining(buffer) <
 594                 qinfo->qname_len+sizeof(uint16_t)*2)
 595                 return RETVAL_TRUNC; /* buffer too small */
 596         /* the query is the first name inserted into the tree */
 597         if(!compress_tree_store(qname, dname_count_labels(qname),
 598                 sldns_buffer_position(buffer), region, NULL, tree))
 599                 return RETVAL_OUTMEM;
 600         if(sldns_buffer_current(buffer) == qname)
 601                 sldns_buffer_skip(buffer, (ssize_t)qname_len);
 602         else    sldns_buffer_write(buffer, qname, qname_len);
 603         sldns_buffer_write_u16(buffer, qinfo->qtype);
 604         sldns_buffer_write_u16(buffer, qinfo->qclass);
 605         return RETVAL_OK;
 606 }
 607
 608 static int
 609 positive_answer(struct reply_info* rep, uint16_t qtype) {
 610         size_t i;
 611         if (FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR)
 612                 return 0;
 613
 614         for(i=0;i<rep->an_numrrsets; i++) {
 615                 if(ntohs(rep->rrsets[i]->rk.type) == qtype) {
 616                         /* in case it is a wildcard with DNSSEC, there will
 617                          * be NSEC/NSEC3 records in the authority section
 618                          * that we cannot remove */
 619                         for(i=rep->an_numrrsets; i<rep->an_numrrsets+
 620                                 rep->ns_numrrsets; i++) {
 621                                 if(ntohs(rep->rrsets[i]->rk.type) ==
 622                                         LDNS_RR_TYPE_NSEC ||
 623                                    ntohs(rep->rrsets[i]->rk.type) ==
 624                                         LDNS_RR_TYPE_NSEC3)
 625                                         return 0;
 626                         }
 627                         return 1;
 628                 }
 629         }
 630         return 0;
 631 }
 632
 633 int
 634 reply_info_encode(struct query_info* qinfo, struct reply_info* rep,
 635         uint16_t id, uint16_t flags, sldns_buffer* buffer, time_t timenow,
 636         struct regional* region, uint16_t udpsize, int dnssec)
 637 {
 638         uint16_t ancount=0, nscount=0, arcount=0;
 639         struct compress_tree_node* tree = 0;
 640         int r;
 641         size_t rr_offset;
 642
 643         sldns_buffer_clear(buffer);
 644         if(udpsize < sldns_buffer_limit(buffer))
 645                 sldns_buffer_set_limit(buffer, udpsize);
 646         if(sldns_buffer_remaining(buffer) < LDNS_HEADER_SIZE)
 647                 return 0;
 648
 649         sldns_buffer_write(buffer, &id, sizeof(uint16_t));
 650         sldns_buffer_write_u16(buffer, flags);
 651         sldns_buffer_write_u16(buffer, rep->qdcount);
 652         /* set an, ns, ar counts to zero in case of small packets */
 653         sldns_buffer_write(buffer, "\000\000\000\000\000\000", 6);
 654
 655         /* insert query section */
 656         if(rep->qdcount) {
 657                 if((r=insert_query(qinfo, &tree, buffer, region)) !=
 658                         RETVAL_OK) {
 659                         if(r == RETVAL_TRUNC) {
 660                                 /* create truncated message */
 661                                 sldns_buffer_write_u16_at(buffer, 4, 0);
 662                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 663                                 sldns_buffer_flip(buffer);
 664                                 return 1;
 665                         }
 666                         return 0;
 667                 }
 668         }
 669         /* roundrobin offset. using query id for random number.  With ntohs
 670          * for different roundrobins for sequential id client senders. */
 671         rr_offset = RRSET_ROUNDROBIN?ntohs(id):0;
 672
 673         /* "prepend" any local alias records in the answer section if this
 674          * response is supposed to be authoritative.  Currently it should
 675          * be a single CNAME record (sanity-checked in worker_handle_request())
 676          * but it can be extended if and when we support more variations of
 677          * aliases. */
 678         if(qinfo->local_alias && (flags & BIT_AA)) {
 679                 struct reply_info arep;
 680                 time_t timezero = 0; /* to use the 'authoritative' TTL */
 681                 memset(&arep, 0, sizeof(arep));
 682                 arep.flags = rep->flags;
 683                 arep.an_numrrsets = 1;
 684                 arep.rrset_count = 1;
 685                 arep.rrsets = &qinfo->local_alias->rrset;
 686                 if((r=insert_section(&arep, 1, &ancount, buffer, 0,
 687                         timezero, region, &tree, LDNS_SECTION_ANSWER,
 688                         qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) {
 689                         if(r == RETVAL_TRUNC) {
 690                                 /* create truncated message */
 691                                 sldns_buffer_write_u16_at(buffer, 6, ancount);
 692                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 693                                 sldns_buffer_flip(buffer);
 694                                 return 1;
 695                         }
 696                         return 0;
 697                 }
 698         }
 699
 700         /* insert answer section */
 701         if((r=insert_section(rep, rep->an_numrrsets, &ancount, buffer,
 702                 0, timenow, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype,
 703                 dnssec, rr_offset)) != RETVAL_OK) {
 704                 if(r == RETVAL_TRUNC) {
 705                         /* create truncated message */
 706                         sldns_buffer_write_u16_at(buffer, 6, ancount);
 707                         LDNS_TC_SET(sldns_buffer_begin(buffer));
 708                         sldns_buffer_flip(buffer);
 709                         return 1;
 710                 }
 711                 return 0;
 712         }
 713         sldns_buffer_write_u16_at(buffer, 6, ancount);
 714
 715         /* if response is positive answer, auth/add sections are not required */
 716         if( ! (MINIMAL_RESPONSES && positive_answer(rep, qinfo->qtype)) ) {
 717                 /* insert auth section */
 718                 if((r=insert_section(rep, rep->ns_numrrsets, &nscount, buffer,
 719                         rep->an_numrrsets, timenow, region, &tree,
 720                         LDNS_SECTION_AUTHORITY, qinfo->qtype,
 721                         dnssec, rr_offset)) != RETVAL_OK) {
 722                         if(r == RETVAL_TRUNC) {
 723                                 /* create truncated message */
 724                                 sldns_buffer_write_u16_at(buffer, 8, nscount);
 725                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 726                                 sldns_buffer_flip(buffer);
 727                                 return 1;
 728                         }
 729                         return 0;
 730                 }
 731                 sldns_buffer_write_u16_at(buffer, 8, nscount);
 732
 733                 /* insert add section */
 734                 if((r=insert_section(rep, rep->ar_numrrsets, &arcount, buffer,
 735                         rep->an_numrrsets + rep->ns_numrrsets, timenow, region,
 736                         &tree, LDNS_SECTION_ADDITIONAL, qinfo->qtype,
 737                         dnssec, rr_offset)) != RETVAL_OK) {
 738                         if(r == RETVAL_TRUNC) {
 739                                 /* no need to set TC bit, this is the additional */
 740                                 sldns_buffer_write_u16_at(buffer, 10, arcount);
 741                                 sldns_buffer_flip(buffer);
 742                                 return 1;
 743                         }
 744                         return 0;
 745                 }
 746                 sldns_buffer_write_u16_at(buffer, 10, arcount);
 747         }
 748         sldns_buffer_flip(buffer);
 749         return 1;
 750 }
 751
 752 uint16_t
 753 calc_edns_field_size(struct edns_data* edns)
 754 {
 755         size_t rdatalen = 0;
 756         struct edns_option* opt;
 757         if(!edns || !edns->edns_present)
 758                 return 0;
 759         for(opt = edns->opt_list; opt; opt = opt->next) {
 760                 rdatalen += 4 + opt->opt_len;
 761         }
 762         /* domain root '.' + type + class + ttl + rdatalen */
 763         return 1 + 2 + 2 + 4 + 2 + rdatalen;
 764 }
 765
 766 void
 767 attach_edns_record(sldns_buffer* pkt, struct edns_data* edns)
 768 {
 769         size_t len;
 770         size_t rdatapos;
 771         struct edns_option* opt;
 772         if(!edns || !edns->edns_present)
 773                 return;
 774         /* inc additional count */
 775         sldns_buffer_write_u16_at(pkt, 10,
 776                 sldns_buffer_read_u16_at(pkt, 10) + 1);
 777         len = sldns_buffer_limit(pkt);
 778         sldns_buffer_clear(pkt);
 779         sldns_buffer_set_position(pkt, len);
 780         /* write EDNS record */
 781         sldns_buffer_write_u8(pkt, 0); /* '.' label */
 782         sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_OPT); /* type */
 783         sldns_buffer_write_u16(pkt, edns->udp_size); /* class */
 784         sldns_buffer_write_u8(pkt, edns->ext_rcode); /* ttl */
 785         sldns_buffer_write_u8(pkt, edns->edns_version);
 786         sldns_buffer_write_u16(pkt, edns->bits);
 787         rdatapos = sldns_buffer_position(pkt);
 788         sldns_buffer_write_u16(pkt, 0); /* rdatalen */
 789         /* write rdata */
 790         for(opt=edns->opt_list; opt; opt=opt->next) {
 791                 sldns_buffer_write_u16(pkt, opt->opt_code);
 792                 sldns_buffer_write_u16(pkt, opt->opt_len);
 793                 if(opt->opt_len != 0)
 794                         sldns_buffer_write(pkt, opt->opt_data, opt->opt_len);
 795         }
 796         if(edns->opt_list)
 797                 sldns_buffer_write_u16_at(pkt, rdatapos,
 798                         sldns_buffer_position(pkt)-rdatapos-2);
 799         sldns_buffer_flip(pkt);
 800 }
 801
 802 int
 803 reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep,
 804         uint16_t id, uint16_t qflags, sldns_buffer* pkt, time_t timenow,
 805         int cached, struct regional* region, uint16_t udpsize,
 806         struct edns_data* edns, int dnssec, int secure)
 807 {
 808         uint16_t flags;
 809         int attach_edns = 1;
 810
 811         if(!cached || rep->authoritative) {
 812                 /* original flags, copy RD and CD bits from query. */
 813                 flags = rep->flags | (qflags & (BIT_RD|BIT_CD));
 814         } else {
 815                 /* remove AA bit, copy RD and CD bits from query. */
 816                 flags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD));
 817         }
 818         if(secure && (dnssec || (qflags&BIT_AD)))
 819                 flags |= BIT_AD;
 820         /* restore AA bit if we have a local alias and the response can be
 821          * authoritative.  Also clear AD bit if set as the local data is the
 822          * primary answer. */
 823         if(qinf->local_alias &&
 824                 (FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR ||
 825                 FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)) {
 826                 flags |= BIT_AA;
 827                 flags &= ~BIT_AD;
 828         }
 829         log_assert(flags & BIT_QR); /* QR bit must be on in our replies */
 830         if(udpsize < LDNS_HEADER_SIZE)
 831                 return 0;
 832         if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) {
 833                 /* packet too small to contain edns, omit it. */
 834                 attach_edns = 0;
 835         } else {
 836                 /* reserve space for edns record */
 837                 udpsize -= calc_edns_field_size(edns);
 838         }
 839
 840         if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region,
 841                 udpsize, dnssec)) {
 842                 log_err("reply encode: out of memory");
 843                 return 0;
 844         }
 845         if(attach_edns)
 846                 attach_edns_record(pkt, edns);
 847         return 1;
 848 }
 849
 850 void
 851 qinfo_query_encode(sldns_buffer* pkt, struct query_info* qinfo)
 852 {
 853         uint16_t flags = 0; /* QUERY, NOERROR */
 854         const uint8_t* qname = qinfo->local_alias ?
 855                 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 856         size_t qname_len = qinfo->local_alias ?
 857                 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len;
 858         sldns_buffer_clear(pkt);
 859         log_assert(sldns_buffer_remaining(pkt) >= 12+255+4/*max query*/);
 860         sldns_buffer_skip(pkt, 2); /* id done later */
 861         sldns_buffer_write_u16(pkt, flags);
 862         sldns_buffer_write_u16(pkt, 1); /* query count */
 863         sldns_buffer_write(pkt, "\000\000\000\000\000\000", 6); /* counts */
 864         sldns_buffer_write(pkt, qname, qname_len);
 865         sldns_buffer_write_u16(pkt, qinfo->qtype);
 866         sldns_buffer_write_u16(pkt, qinfo->qclass);
 867         sldns_buffer_flip(pkt);
 868 }
 869
 870 void
 871 error_encode(sldns_buffer* buf, int r, struct query_info* qinfo,
 872         uint16_t qid, uint16_t qflags, struct edns_data* edns)
 873 {
 874         uint16_t flags;
 875
 876         sldns_buffer_clear(buf);
 877         sldns_buffer_write(buf, &qid, sizeof(uint16_t));
 878         flags = (uint16_t)(BIT_QR | BIT_RA | r); /* QR and retcode*/
 879         flags |= (qflags & (BIT_RD|BIT_CD)); /* copy RD and CD bit */
 880         sldns_buffer_write_u16(buf, flags);
 881         if(qinfo) flags = 1;
 882         else    flags = 0;
 883         sldns_buffer_write_u16(buf, flags);
 884         flags = 0;
 885         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 886         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 887         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 888         if(qinfo) {
 889                 const uint8_t* qname = qinfo->local_alias ?
 890                         qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 891                 size_t qname_len = qinfo->local_alias ?
 892                         qinfo->local_alias->rrset->rk.dname_len :
 893                         qinfo->qname_len;
 894                 if(sldns_buffer_current(buf) == qname)
 895                         sldns_buffer_skip(buf, (ssize_t)qname_len);
 896                 else    sldns_buffer_write(buf, qname, qname_len);
 897                 sldns_buffer_write_u16(buf, qinfo->qtype);
 898                 sldns_buffer_write_u16(buf, qinfo->qclass);
 899         }
 900         sldns_buffer_flip(buf);
 901         if(edns) {
 902                 struct edns_data es = *edns;
 903                 es.edns_version = EDNS_ADVERTISED_VERSION;
 904                 es.udp_size = EDNS_ADVERTISED_SIZE;
 905                 es.ext_rcode = 0;
 906                 es.bits &= EDNS_DO;
 907                 if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
 908                         edns->udp_size)
 909                         return;
 910                 attach_edns_record(buf, &es);
 911         }
 912 }