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         /* For an rrset with a fixed TTL, use the rrset's TTL as given */
 463         if((key->rk.flags & PACKED_RRSET_FIXEDTTL) != 0)
 464                 timenow = 0;
 465
 466         if(do_data) {
 467                 const sldns_rr_descriptor* c = type_rdata_compressable(key);
 468                 for(i=0; i<data->count; i++) {
 469                         /* rrset roundrobin */
 470                         j = (i + rr_offset) % data->count;
 471                         if((r=compress_owner(key, pkt, region, tree,
 472                                 owner_pos, &owner_ptr, owner_labs))
 473                                 != RETVAL_OK)
 474                                 return r;
 475                         sldns_buffer_write(pkt, &key->rk.type, 2);
 476                         sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
 477                         if(data->rr_ttl[j] < timenow)
 478                                 sldns_buffer_write_u32(pkt, 0);
 479                         else    sldns_buffer_write_u32(pkt,
 480                                         data->rr_ttl[j]-timenow);
 481                         if(c) {
 482                                 if((r=compress_rdata(pkt, data->rr_data[j],
 483                                         data->rr_len[j], region, tree, c))
 484                                         != RETVAL_OK)
 485                                         return r;
 486                         } else {
 487                                 if(sldns_buffer_remaining(pkt) < data->rr_len[j])
 488                                         return RETVAL_TRUNC;
 489                                 sldns_buffer_write(pkt, data->rr_data[j],
 490                                         data->rr_len[j]);
 491                         }
 492                 }
 493         }
 494         /* insert rrsigs */
 495         if(do_sig && dnssec) {
 496                 size_t total = data->count+data->rrsig_count;
 497                 for(i=data->count; i<total; i++) {
 498                         if(owner_ptr && owner_labs != 1) {
 499                                 if(sldns_buffer_remaining(pkt) <
 500                                         2+4+4+data->rr_len[i])
 501                                         return RETVAL_TRUNC;
 502                                 sldns_buffer_write(pkt, &owner_ptr, 2);
 503                         } else {
 504                                 if((r=compress_any_dname(key->rk.dname,
 505                                         pkt, owner_labs, region, tree))
 506                                         != RETVAL_OK)
 507                                         return r;
 508                                 if(sldns_buffer_remaining(pkt) <
 509                                         4+4+data->rr_len[i])
 510                                         return RETVAL_TRUNC;
 511                         }
 512                         sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_RRSIG);
 513                         sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
 514                         if(data->rr_ttl[i] < timenow)
 515                                 sldns_buffer_write_u32(pkt, 0);
 516                         else    sldns_buffer_write_u32(pkt,
 517                                         data->rr_ttl[i]-timenow);
 518                         /* rrsig rdata cannot be compressed, perform 100+ byte
 519                          * memcopy. */
 520                         sldns_buffer_write(pkt, data->rr_data[i],
 521                                 data->rr_len[i]);
 522                 }
 523         }
 524         /* change rrnum only after we are sure it fits */
 525         if(do_data)
 526                 *num_rrs += data->count;
 527         if(do_sig && dnssec)
 528                 *num_rrs += data->rrsig_count;
 529
 530         return RETVAL_OK;
 531 }
 532
 533 /** store msg section in wireformat buffer, return RETVAL_* */
 534 static int
 535 insert_section(struct reply_info* rep, size_t num_rrsets, uint16_t* num_rrs,
 536         sldns_buffer* pkt, size_t rrsets_before, time_t timenow,
 537         struct regional* region, struct compress_tree_node** tree,
 538         sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset)
 539 {
 540         int r;
 541         size_t i, setstart;
 542         /* we now allow this function to be called multiple times for the
 543          * same section, incrementally updating num_rrs.  The caller is
 544          * responsible for initializing it (which is the case in the current
 545          * implementation). */
 546
 547         if(s != LDNS_SECTION_ADDITIONAL) {
 548                 if(s == LDNS_SECTION_ANSWER && qtype == LDNS_RR_TYPE_ANY)
 549                         dnssec = 1; /* include all types in ANY answer */
 550                 for(i=0; i<num_rrsets; i++) {
 551                         setstart = sldns_buffer_position(pkt);
 552                         if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
 553                                 pkt, num_rrs, timenow, region, 1, 1, tree,
 554                                 s, qtype, dnssec, rr_offset))
 555                                 != RETVAL_OK) {
 556                                 /* Bad, but if due to size must set TC bit */
 557                                 /* trim off the rrset neatly. */
 558                                 sldns_buffer_set_position(pkt, setstart);
 559                                 return r;
 560                         }
 561                 }
 562         } else {
 563                 for(i=0; i<num_rrsets; i++) {
 564                         setstart = sldns_buffer_position(pkt);
 565                         if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
 566                                 pkt, num_rrs, timenow, region, 1, 0, tree,
 567                                 s, qtype, dnssec, rr_offset))
 568                                 != RETVAL_OK) {
 569                                 sldns_buffer_set_position(pkt, setstart);
 570                                 return r;
 571                         }
 572                 }
 573                 if(dnssec)
 574                   for(i=0; i<num_rrsets; i++) {
 575                         setstart = sldns_buffer_position(pkt);
 576                         if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
 577                                 pkt, num_rrs, timenow, region, 0, 1, tree,
 578                                 s, qtype, dnssec, rr_offset))
 579                                 != RETVAL_OK) {
 580                                 sldns_buffer_set_position(pkt, setstart);
 581                                 return r;
 582                         }
 583                   }
 584         }
 585         return RETVAL_OK;
 586 }
 587
 588 /** store query section in wireformat buffer, return RETVAL */
 589 static int
 590 insert_query(struct query_info* qinfo, struct compress_tree_node** tree,
 591         sldns_buffer* buffer, struct regional* region)
 592 {
 593         uint8_t* qname = qinfo->local_alias ?
 594                 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 595         size_t qname_len = qinfo->local_alias ?
 596                 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len;
 597         if(sldns_buffer_remaining(buffer) <
 598                 qinfo->qname_len+sizeof(uint16_t)*2)
 599                 return RETVAL_TRUNC; /* buffer too small */
 600         /* the query is the first name inserted into the tree */
 601         if(!compress_tree_store(qname, dname_count_labels(qname),
 602                 sldns_buffer_position(buffer), region, NULL, tree))
 603                 return RETVAL_OUTMEM;
 604         if(sldns_buffer_current(buffer) == qname)
 605                 sldns_buffer_skip(buffer, (ssize_t)qname_len);
 606         else    sldns_buffer_write(buffer, qname, qname_len);
 607         sldns_buffer_write_u16(buffer, qinfo->qtype);
 608         sldns_buffer_write_u16(buffer, qinfo->qclass);
 609         return RETVAL_OK;
 610 }
 611
 612 static int
 613 positive_answer(struct reply_info* rep, uint16_t qtype) {
 614         size_t i;
 615         if (FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR)
 616                 return 0;
 617
 618         for(i=0;i<rep->an_numrrsets; i++) {
 619                 if(ntohs(rep->rrsets[i]->rk.type) == qtype) {
 620                         /* in case it is a wildcard with DNSSEC, there will
 621                          * be NSEC/NSEC3 records in the authority section
 622                          * that we cannot remove */
 623                         for(i=rep->an_numrrsets; i<rep->an_numrrsets+
 624                                 rep->ns_numrrsets; i++) {
 625                                 if(ntohs(rep->rrsets[i]->rk.type) ==
 626                                         LDNS_RR_TYPE_NSEC ||
 627                                    ntohs(rep->rrsets[i]->rk.type) ==
 628                                         LDNS_RR_TYPE_NSEC3)
 629                                         return 0;
 630                         }
 631                         return 1;
 632                 }
 633         }
 634         return 0;
 635 }
 636
 637 int
 638 reply_info_encode(struct query_info* qinfo, struct reply_info* rep,
 639         uint16_t id, uint16_t flags, sldns_buffer* buffer, time_t timenow,
 640         struct regional* region, uint16_t udpsize, int dnssec)
 641 {
 642         uint16_t ancount=0, nscount=0, arcount=0;
 643         struct compress_tree_node* tree = 0;
 644         int r;
 645         size_t rr_offset;
 646
 647         sldns_buffer_clear(buffer);
 648         if(udpsize < sldns_buffer_limit(buffer))
 649                 sldns_buffer_set_limit(buffer, udpsize);
 650         else if(sldns_buffer_limit(buffer) < udpsize)
 651                 udpsize = sldns_buffer_limit(buffer);
 652         if(sldns_buffer_remaining(buffer) < LDNS_HEADER_SIZE)
 653                 return 0;
 654
 655         sldns_buffer_write(buffer, &id, sizeof(uint16_t));
 656         sldns_buffer_write_u16(buffer, flags);
 657         sldns_buffer_write_u16(buffer, rep->qdcount);
 658         /* set an, ns, ar counts to zero in case of small packets */
 659         sldns_buffer_write(buffer, "\000\000\000\000\000\000", 6);
 660
 661         /* insert query section */
 662         if(rep->qdcount) {
 663                 if((r=insert_query(qinfo, &tree, buffer, region)) !=
 664                         RETVAL_OK) {
 665                         if(r == RETVAL_TRUNC) {
 666                                 /* create truncated message */
 667                                 sldns_buffer_write_u16_at(buffer, 4, 0);
 668                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 669                                 sldns_buffer_flip(buffer);
 670                                 return 1;
 671                         }
 672                         return 0;
 673                 }
 674         }
 675         /* roundrobin offset. using query id for random number.  With ntohs
 676          * for different roundrobins for sequential id client senders. */
 677         rr_offset = RRSET_ROUNDROBIN?ntohs(id):0;
 678
 679         /* "prepend" any local alias records in the answer section if this
 680          * response is supposed to be authoritative.  Currently it should
 681          * be a single CNAME record (sanity-checked in worker_handle_request())
 682          * but it can be extended if and when we support more variations of
 683          * aliases. */
 684         if(qinfo->local_alias && (flags & BIT_AA)) {
 685                 struct reply_info arep;
 686                 time_t timezero = 0; /* to use the 'authoritative' TTL */
 687                 memset(&arep, 0, sizeof(arep));
 688                 arep.flags = rep->flags;
 689                 arep.an_numrrsets = 1;
 690                 arep.rrset_count = 1;
 691                 arep.rrsets = &qinfo->local_alias->rrset;
 692                 if((r=insert_section(&arep, 1, &ancount, buffer, 0,
 693                         timezero, region, &tree, LDNS_SECTION_ANSWER,
 694                         qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) {
 695                         if(r == RETVAL_TRUNC) {
 696                                 /* create truncated message */
 697                                 sldns_buffer_write_u16_at(buffer, 6, ancount);
 698                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 699                                 sldns_buffer_flip(buffer);
 700                                 return 1;
 701                         }
 702                         return 0;
 703                 }
 704         }
 705
 706         /* insert answer section */
 707         if((r=insert_section(rep, rep->an_numrrsets, &ancount, buffer,
 708                 0, timenow, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype,
 709                 dnssec, rr_offset)) != RETVAL_OK) {
 710                 if(r == RETVAL_TRUNC) {
 711                         /* create truncated message */
 712                         sldns_buffer_write_u16_at(buffer, 6, ancount);
 713                         LDNS_TC_SET(sldns_buffer_begin(buffer));
 714                         sldns_buffer_flip(buffer);
 715                         return 1;
 716                 }
 717                 return 0;
 718         }
 719         sldns_buffer_write_u16_at(buffer, 6, ancount);
 720
 721         /* if response is positive answer, auth/add sections are not required */
 722         if( ! (MINIMAL_RESPONSES && positive_answer(rep, qinfo->qtype)) ) {
 723                 /* insert auth section */
 724                 if((r=insert_section(rep, rep->ns_numrrsets, &nscount, buffer,
 725                         rep->an_numrrsets, timenow, region, &tree,
 726                         LDNS_SECTION_AUTHORITY, qinfo->qtype,
 727                         dnssec, rr_offset)) != RETVAL_OK) {
 728                         if(r == RETVAL_TRUNC) {
 729                                 /* create truncated message */
 730                                 sldns_buffer_write_u16_at(buffer, 8, nscount);
 731                                 LDNS_TC_SET(sldns_buffer_begin(buffer));
 732                                 sldns_buffer_flip(buffer);
 733                                 return 1;
 734                         }
 735                         return 0;
 736                 }
 737                 sldns_buffer_write_u16_at(buffer, 8, nscount);
 738
 739                 /* insert add section */
 740                 if((r=insert_section(rep, rep->ar_numrrsets, &arcount, buffer,
 741                         rep->an_numrrsets + rep->ns_numrrsets, timenow, region,
 742                         &tree, LDNS_SECTION_ADDITIONAL, qinfo->qtype,
 743                         dnssec, rr_offset)) != RETVAL_OK) {
 744                         if(r == RETVAL_TRUNC) {
 745                                 /* no need to set TC bit, this is the additional */
 746                                 sldns_buffer_write_u16_at(buffer, 10, arcount);
 747                                 sldns_buffer_flip(buffer);
 748                                 return 1;
 749                         }
 750                         return 0;
 751                 }
 752                 sldns_buffer_write_u16_at(buffer, 10, arcount);
 753         }
 754         sldns_buffer_flip(buffer);
 755         return 1;
 756 }
 757
 758 uint16_t
 759 calc_edns_field_size(struct edns_data* edns)
 760 {
 761         size_t rdatalen = 0;
 762         struct edns_option* opt;
 763         if(!edns || !edns->edns_present)
 764                 return 0;
 765         for(opt = edns->opt_list; opt; opt = opt->next) {
 766                 rdatalen += 4 + opt->opt_len;
 767         }
 768         /* domain root '.' + type + class + ttl + rdatalen */
 769         return 1 + 2 + 2 + 4 + 2 + rdatalen;
 770 }
 771
 772 void
 773 attach_edns_record(sldns_buffer* pkt, struct edns_data* edns)
 774 {
 775         size_t len;
 776         size_t rdatapos;
 777         struct edns_option* opt;
 778         if(!edns || !edns->edns_present)
 779                 return;
 780         /* inc additional count */
 781         sldns_buffer_write_u16_at(pkt, 10,
 782                 sldns_buffer_read_u16_at(pkt, 10) + 1);
 783         len = sldns_buffer_limit(pkt);
 784         sldns_buffer_clear(pkt);
 785         sldns_buffer_set_position(pkt, len);
 786         /* write EDNS record */
 787         sldns_buffer_write_u8(pkt, 0); /* '.' label */
 788         sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_OPT); /* type */
 789         sldns_buffer_write_u16(pkt, edns->udp_size); /* class */
 790         sldns_buffer_write_u8(pkt, edns->ext_rcode); /* ttl */
 791         sldns_buffer_write_u8(pkt, edns->edns_version);
 792         sldns_buffer_write_u16(pkt, edns->bits);
 793         rdatapos = sldns_buffer_position(pkt);
 794         sldns_buffer_write_u16(pkt, 0); /* rdatalen */
 795         /* write rdata */
 796         for(opt=edns->opt_list; opt; opt=opt->next) {
 797                 sldns_buffer_write_u16(pkt, opt->opt_code);
 798                 sldns_buffer_write_u16(pkt, opt->opt_len);
 799                 if(opt->opt_len != 0)
 800                         sldns_buffer_write(pkt, opt->opt_data, opt->opt_len);
 801         }
 802         if(edns->opt_list)
 803                 sldns_buffer_write_u16_at(pkt, rdatapos,
 804                         sldns_buffer_position(pkt)-rdatapos-2);
 805         sldns_buffer_flip(pkt);
 806 }
 807
 808 int
 809 reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep,
 810         uint16_t id, uint16_t qflags, sldns_buffer* pkt, time_t timenow,
 811         int cached, struct regional* region, uint16_t udpsize,
 812         struct edns_data* edns, int dnssec, int secure)
 813 {
 814         uint16_t flags;
 815         unsigned int attach_edns = 0;
 816
 817         if(!cached || rep->authoritative) {
 818                 /* original flags, copy RD and CD bits from query. */
 819                 flags = rep->flags | (qflags & (BIT_RD|BIT_CD));
 820         } else {
 821                 /* remove AA bit, copy RD and CD bits from query. */
 822                 flags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD));
 823         }
 824         if(secure && (dnssec || (qflags&BIT_AD)))
 825                 flags |= BIT_AD;
 826         /* restore AA bit if we have a local alias and the response can be
 827          * authoritative.  Also clear AD bit if set as the local data is the
 828          * primary answer. */
 829         if(qinf->local_alias &&
 830                 (FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR ||
 831                 FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)) {
 832                 flags |= BIT_AA;
 833                 flags &= ~BIT_AD;
 834         }
 835         log_assert(flags & BIT_QR); /* QR bit must be on in our replies */
 836         if(udpsize < LDNS_HEADER_SIZE)
 837                 return 0;
 838         if(sldns_buffer_capacity(pkt) < udpsize)
 839                 udpsize = sldns_buffer_capacity(pkt);
 840         if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) {
 841                 /* packet too small to contain edns, omit it. */
 842                 attach_edns = 0;
 843         } else {
 844                 /* reserve space for edns record */
 845                 attach_edns = (unsigned int)calc_edns_field_size(edns);
 846                 udpsize -= attach_edns;
 847         }
 848
 849         if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region,
 850                 udpsize, dnssec)) {
 851                 log_err("reply encode: out of memory");
 852                 return 0;
 853         }
 854         if(attach_edns && sldns_buffer_capacity(pkt) >=
 855                 sldns_buffer_limit(pkt)+attach_edns)
 856                 attach_edns_record(pkt, edns);
 857         return 1;
 858 }
 859
 860 void
 861 qinfo_query_encode(sldns_buffer* pkt, struct query_info* qinfo)
 862 {
 863         uint16_t flags = 0; /* QUERY, NOERROR */
 864         const uint8_t* qname = qinfo->local_alias ?
 865                 qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 866         size_t qname_len = qinfo->local_alias ?
 867                 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len;
 868         sldns_buffer_clear(pkt);
 869         log_assert(sldns_buffer_remaining(pkt) >= 12+255+4/*max query*/);
 870         sldns_buffer_skip(pkt, 2); /* id done later */
 871         sldns_buffer_write_u16(pkt, flags);
 872         sldns_buffer_write_u16(pkt, 1); /* query count */
 873         sldns_buffer_write(pkt, "\000\000\000\000\000\000", 6); /* counts */
 874         sldns_buffer_write(pkt, qname, qname_len);
 875         sldns_buffer_write_u16(pkt, qinfo->qtype);
 876         sldns_buffer_write_u16(pkt, qinfo->qclass);
 877         sldns_buffer_flip(pkt);
 878 }
 879
 880 void
 881 error_encode(sldns_buffer* buf, int r, struct query_info* qinfo,
 882         uint16_t qid, uint16_t qflags, struct edns_data* edns)
 883 {
 884         uint16_t flags;
 885
 886         sldns_buffer_clear(buf);
 887         sldns_buffer_write(buf, &qid, sizeof(uint16_t));
 888         flags = (uint16_t)(BIT_QR | BIT_RA | r); /* QR and retcode*/
 889         flags |= (qflags & (BIT_RD|BIT_CD)); /* copy RD and CD bit */
 890         sldns_buffer_write_u16(buf, flags);
 891         if(qinfo) flags = 1;
 892         else    flags = 0;
 893         sldns_buffer_write_u16(buf, flags);
 894         flags = 0;
 895         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 896         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 897         sldns_buffer_write(buf, &flags, sizeof(uint16_t));
 898         if(qinfo) {
 899                 const uint8_t* qname = qinfo->local_alias ?
 900                         qinfo->local_alias->rrset->rk.dname : qinfo->qname;
 901                 size_t qname_len = qinfo->local_alias ?
 902                         qinfo->local_alias->rrset->rk.dname_len :
 903                         qinfo->qname_len;
 904                 if(sldns_buffer_current(buf) == qname)
 905                         sldns_buffer_skip(buf, (ssize_t)qname_len);
 906                 else    sldns_buffer_write(buf, qname, qname_len);
 907                 sldns_buffer_write_u16(buf, qinfo->qtype);
 908                 sldns_buffer_write_u16(buf, qinfo->qclass);
 909         }
 910         sldns_buffer_flip(buf);
 911         if(edns) {
 912                 struct edns_data es = *edns;
 913                 es.edns_version = EDNS_ADVERTISED_VERSION;
 914                 es.udp_size = EDNS_ADVERTISED_SIZE;
 915                 es.ext_rcode = 0;
 916                 es.bits &= EDNS_DO;
 917                 if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
 918                         edns->udp_size)
 919                         return;
 920                 attach_edns_record(buf, &es);
 921         }
 922 }