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 } 913