msgencode.c revision 356345
1/* 2 * util/data/msgencode.c - Encode DNS messages, queries and replies. 3 * 4 * Copyright (c) 2007, NLnet Labs. All rights reserved. 5 * 6 * This software is open source. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * Redistributions of source code must retain the above copyright notice, 13 * this list of conditions and the following disclaimer. 14 * 15 * Redistributions in binary form must reproduce the above copyright notice, 16 * this list of conditions and the following disclaimer in the documentation 17 * and/or other materials provided with the distribution. 18 * 19 * Neither the name of the NLNET LABS nor the names of its contributors may 20 * be used to endorse or promote products derived from this software without 21 * specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36/** 37 * \file 38 * 39 * This file contains a routines to encode DNS messages. 40 */ 41 42#include "config.h" 43#include "util/data/msgencode.h" 44#include "util/data/msgreply.h" 45#include "util/data/msgparse.h" 46#include "util/data/dname.h" 47#include "util/log.h" 48#include "util/regional.h" 49#include "util/net_help.h" 50#include "sldns/sbuffer.h" 51#include "services/localzone.h" 52 53#ifdef HAVE_TIME_H 54#include <time.h> 55#endif 56#include <sys/time.h> 57 58/** return code that means the function ran out of memory. negative so it does 59 * not conflict with DNS rcodes. */ 60#define RETVAL_OUTMEM -2 61/** return code that means the data did not fit (completely) in the packet */ 62#define RETVAL_TRUNC -4 63/** return code that means all is peachy keen. Equal to DNS rcode NOERROR */ 64#define RETVAL_OK 0 65 66/** 67 * Data structure to help domain name compression in outgoing messages. 68 * A tree of dnames and their offsets in the packet is kept. 69 * It is kept sorted, not canonical, but by label at least, so that after 70 * a lookup of a name you know its closest match, and the parent from that 71 * closest match. These are possible compression targets. 72 * 73 * It is a binary tree, not a rbtree or balanced tree, as the effort 74 * of keeping it balanced probably outweighs usefulness (given typical 75 * DNS packet size). 76 */ 77struct compress_tree_node { 78 /** left node in tree, all smaller to this */ 79 struct compress_tree_node* left; 80 /** right node in tree, all larger than this */ 81 struct compress_tree_node* right; 82 83 /** the parent node - not for tree, but zone parent. One less label */ 84 struct compress_tree_node* parent; 85 /** the domain name for this node. Pointer to uncompressed memory. */ 86 uint8_t* dname; 87 /** number of labels in domain name, kept to help compare func. */ 88 int labs; 89 /** offset in packet that points to this dname */ 90 size_t offset; 91}; 92 93/** 94 * Find domain name in tree, returns exact and closest match. 95 * @param tree: root of tree. 96 * @param dname: pointer to uncompressed dname. 97 * @param labs: number of labels in domain name. 98 * @param match: closest or exact match. 99 * guaranteed to be smaller or equal to the sought dname. 100 * can be null if the tree is empty. 101 * @param matchlabels: number of labels that match with closest match. 102 * can be zero is there is no match. 103 * @param insertpt: insert location for dname, if not found. 104 * @return: 0 if no exact match. 105 */ 106static int 107compress_tree_search(struct compress_tree_node** tree, uint8_t* dname, 108 int labs, struct compress_tree_node** match, int* matchlabels, 109 struct compress_tree_node*** insertpt) 110{ 111 int c, n, closen=0; 112 struct compress_tree_node* p = *tree; 113 struct compress_tree_node* close = 0; 114 struct compress_tree_node** prev = tree; 115 while(p) { 116 if((c = dname_lab_cmp(dname, labs, p->dname, p->labs, &n)) 117 == 0) { 118 *matchlabels = n; 119 *match = p; 120 return 1; 121 } 122 if(c<0) { 123 prev = &p->left; 124 p = p->left; 125 } else { 126 closen = n; 127 close = p; /* p->dname is smaller than dname */ 128 prev = &p->right; 129 p = p->right; 130 } 131 } 132 *insertpt = prev; 133 *matchlabels = closen; 134 *match = close; 135 return 0; 136} 137 138/** 139 * Lookup a domain name in compression tree. 140 * @param tree: root of tree (not the node with '.'). 141 * @param dname: pointer to uncompressed dname. 142 * @param labs: number of labels in domain name. 143 * @param insertpt: insert location for dname, if not found. 144 * @return: 0 if not found or compress treenode with best compression. 145 */ 146static struct compress_tree_node* 147compress_tree_lookup(struct compress_tree_node** tree, uint8_t* dname, 148 int labs, struct compress_tree_node*** insertpt) 149{ 150 struct compress_tree_node* p; 151 int m; 152 if(labs <= 1) 153 return 0; /* do not compress root node */ 154 if(compress_tree_search(tree, dname, labs, &p, &m, insertpt)) { 155 /* exact match */ 156 return p; 157 } 158 /* return some ancestor of p that compresses well. */ 159 if(m>1) { 160 /* www.example.com. (labs=4) matched foo.example.com.(labs=4) 161 * then matchcount = 3. need to go up. */ 162 while(p && p->labs > m) 163 p = p->parent; 164 return p; 165 } 166 return 0; 167} 168 169/** 170 * Create node for domain name compression tree. 171 * @param dname: pointer to uncompressed dname (stored in tree). 172 * @param labs: number of labels in dname. 173 * @param offset: offset into packet for dname. 174 * @param region: how to allocate memory for new node. 175 * @return new node or 0 on malloc failure. 176 */ 177static struct compress_tree_node* 178compress_tree_newnode(uint8_t* dname, int labs, size_t offset, 179 struct regional* region) 180{ 181 struct compress_tree_node* n = (struct compress_tree_node*) 182 regional_alloc(region, sizeof(struct compress_tree_node)); 183 if(!n) return 0; 184 n->left = 0; 185 n->right = 0; 186 n->parent = 0; 187 n->dname = dname; 188 n->labs = labs; 189 n->offset = offset; 190 return n; 191} 192 193/** 194 * Store domain name and ancestors into compression tree. 195 * @param dname: pointer to uncompressed dname (stored in tree). 196 * @param labs: number of labels in dname. 197 * @param offset: offset into packet for dname. 198 * @param region: how to allocate memory for new node. 199 * @param closest: match from previous lookup, used to compress dname. 200 * may be NULL if no previous match. 201 * if the tree has an ancestor of dname already, this must be it. 202 * @param insertpt: where to insert the dname in tree. 203 * @return: 0 on memory error. 204 */ 205static int 206compress_tree_store(uint8_t* dname, int labs, size_t offset, 207 struct regional* region, struct compress_tree_node* closest, 208 struct compress_tree_node** insertpt) 209{ 210 uint8_t lablen; 211 struct compress_tree_node* newnode; 212 struct compress_tree_node* prevnode = NULL; 213 int uplabs = labs-1; /* does not store root in tree */ 214 if(closest) uplabs = labs - closest->labs; 215 log_assert(uplabs >= 0); 216 /* algorithms builds up a vine of dname-labels to hang into tree */ 217 while(uplabs--) { 218 if(offset > PTR_MAX_OFFSET) { 219 /* insertion failed, drop vine */ 220 return 1; /* compression pointer no longer useful */ 221 } 222 if(!(newnode = compress_tree_newnode(dname, labs, offset, 223 region))) { 224 /* insertion failed, drop vine */ 225 return 0; 226 } 227 228 if(prevnode) { 229 /* chain nodes together, last one has one label more, 230 * so is larger than newnode, thus goes right. */ 231 newnode->right = prevnode; 232 prevnode->parent = newnode; 233 } 234 235 /* next label */ 236 lablen = *dname++; 237 dname += lablen; 238 offset += lablen+1; 239 prevnode = newnode; 240 labs--; 241 } 242 /* if we have a vine, hang the vine into the tree */ 243 if(prevnode) { 244 *insertpt = prevnode; 245 prevnode->parent = closest; 246 } 247 return 1; 248} 249 250/** compress a domain name */ 251static int 252write_compressed_dname(sldns_buffer* pkt, uint8_t* dname, int labs, 253 struct compress_tree_node* p) 254{ 255 /* compress it */ 256 int labcopy = labs - p->labs; 257 uint8_t lablen; 258 uint16_t ptr; 259 260 if(labs == 1) { 261 /* write root label */ 262 if(sldns_buffer_remaining(pkt) < 1) 263 return 0; 264 sldns_buffer_write_u8(pkt, 0); 265 return 1; 266 } 267 268 /* copy the first couple of labels */ 269 while(labcopy--) { 270 lablen = *dname++; 271 if(sldns_buffer_remaining(pkt) < (size_t)lablen+1) 272 return 0; 273 sldns_buffer_write_u8(pkt, lablen); 274 sldns_buffer_write(pkt, dname, lablen); 275 dname += lablen; 276 } 277 /* insert compression ptr */ 278 if(sldns_buffer_remaining(pkt) < 2) 279 return 0; 280 ptr = PTR_CREATE(p->offset); 281 sldns_buffer_write_u16(pkt, ptr); 282 return 1; 283} 284 285/** compress owner name of RR, return RETVAL_OUTMEM RETVAL_TRUNC */ 286static int 287compress_owner(struct ub_packed_rrset_key* key, sldns_buffer* pkt, 288 struct regional* region, struct compress_tree_node** tree, 289 size_t owner_pos, uint16_t* owner_ptr, int owner_labs) 290{ 291 struct compress_tree_node* p; 292 struct compress_tree_node** insertpt = NULL; 293 if(!*owner_ptr) { 294 /* compress first time dname */ 295 if((p = compress_tree_lookup(tree, key->rk.dname, 296 owner_labs, &insertpt))) { 297 if(p->labs == owner_labs) 298 /* avoid ptr chains, since some software is 299 * not capable of decoding ptr after a ptr. */ 300 *owner_ptr = htons(PTR_CREATE(p->offset)); 301 if(!write_compressed_dname(pkt, key->rk.dname, 302 owner_labs, p)) 303 return RETVAL_TRUNC; 304 /* check if typeclass+4 ttl + rdatalen is available */ 305 if(sldns_buffer_remaining(pkt) < 4+4+2) 306 return RETVAL_TRUNC; 307 } else { 308 /* no compress */ 309 if(sldns_buffer_remaining(pkt) < key->rk.dname_len+4+4+2) 310 return RETVAL_TRUNC; 311 sldns_buffer_write(pkt, key->rk.dname, 312 key->rk.dname_len); 313 if(owner_pos <= PTR_MAX_OFFSET) 314 *owner_ptr = htons(PTR_CREATE(owner_pos)); 315 } 316 if(!compress_tree_store(key->rk.dname, owner_labs, 317 owner_pos, region, p, insertpt)) 318 return RETVAL_OUTMEM; 319 } else { 320 /* always compress 2nd-further RRs in RRset */ 321 if(owner_labs == 1) { 322 if(sldns_buffer_remaining(pkt) < 1+4+4+2) 323 return RETVAL_TRUNC; 324 sldns_buffer_write_u8(pkt, 0); 325 } else { 326 if(sldns_buffer_remaining(pkt) < 2+4+4+2) 327 return RETVAL_TRUNC; 328 sldns_buffer_write(pkt, owner_ptr, 2); 329 } 330 } 331 return RETVAL_OK; 332} 333 334/** compress any domain name to the packet, return RETVAL_* */ 335static int 336compress_any_dname(uint8_t* dname, sldns_buffer* pkt, int labs, 337 struct regional* region, struct compress_tree_node** tree) 338{ 339 struct compress_tree_node* p; 340 struct compress_tree_node** insertpt = NULL; 341 size_t pos = sldns_buffer_position(pkt); 342 if((p = compress_tree_lookup(tree, dname, labs, &insertpt))) { 343 if(!write_compressed_dname(pkt, dname, labs, p)) 344 return RETVAL_TRUNC; 345 } else { 346 if(!dname_buffer_write(pkt, dname)) 347 return RETVAL_TRUNC; 348 } 349 if(!compress_tree_store(dname, labs, pos, region, p, insertpt)) 350 return RETVAL_OUTMEM; 351 return RETVAL_OK; 352} 353 354/** return true if type needs domain name compression in rdata */ 355static const sldns_rr_descriptor* 356type_rdata_compressable(struct ub_packed_rrset_key* key) 357{ 358 uint16_t t = ntohs(key->rk.type); 359 if(sldns_rr_descript(t) && 360 sldns_rr_descript(t)->_compress == LDNS_RR_COMPRESS) 361 return sldns_rr_descript(t); 362 return 0; 363} 364 365/** compress domain names in rdata, return RETVAL_* */ 366static int 367compress_rdata(sldns_buffer* pkt, uint8_t* rdata, size_t todolen, 368 struct regional* region, struct compress_tree_node** tree, 369 const sldns_rr_descriptor* desc) 370{ 371 int labs, r, rdf = 0; 372 size_t dname_len, len, pos = sldns_buffer_position(pkt); 373 uint8_t count = desc->_dname_count; 374 375 sldns_buffer_skip(pkt, 2); /* rdata len fill in later */ 376 /* space for rdatalen checked for already */ 377 rdata += 2; 378 todolen -= 2; 379 while(todolen > 0 && count) { 380 switch(desc->_wireformat[rdf]) { 381 case LDNS_RDF_TYPE_DNAME: 382 labs = dname_count_size_labels(rdata, &dname_len); 383 if((r=compress_any_dname(rdata, pkt, labs, region, 384 tree)) != RETVAL_OK) 385 return r; 386 rdata += dname_len; 387 todolen -= dname_len; 388 count--; 389 len = 0; 390 break; 391 case LDNS_RDF_TYPE_STR: 392 len = *rdata + 1; 393 break; 394 default: 395 len = get_rdf_size(desc->_wireformat[rdf]); 396 } 397 if(len) { 398 /* copy over */ 399 if(sldns_buffer_remaining(pkt) < len) 400 return RETVAL_TRUNC; 401 sldns_buffer_write(pkt, rdata, len); 402 todolen -= len; 403 rdata += len; 404 } 405 rdf++; 406 } 407 /* copy remainder */ 408 if(todolen > 0) { 409 if(sldns_buffer_remaining(pkt) < todolen) 410 return RETVAL_TRUNC; 411 sldns_buffer_write(pkt, rdata, todolen); 412 } 413 414 /* set rdata len */ 415 sldns_buffer_write_u16_at(pkt, pos, sldns_buffer_position(pkt)-pos-2); 416 return RETVAL_OK; 417} 418 419/** Returns true if RR type should be included */ 420static int 421rrset_belongs_in_reply(sldns_pkt_section s, uint16_t rrtype, uint16_t qtype, 422 int dnssec) 423{ 424 if(dnssec) 425 return 1; 426 /* skip non DNSSEC types, except if directly queried for */ 427 if(s == LDNS_SECTION_ANSWER) { 428 if(qtype == LDNS_RR_TYPE_ANY || qtype == rrtype) 429 return 1; 430 } 431 /* check DNSSEC-ness */ 432 switch(rrtype) { 433 case LDNS_RR_TYPE_SIG: 434 case LDNS_RR_TYPE_KEY: 435 case LDNS_RR_TYPE_NXT: 436 case LDNS_RR_TYPE_DS: 437 case LDNS_RR_TYPE_RRSIG: 438 case LDNS_RR_TYPE_NSEC: 439 case LDNS_RR_TYPE_DNSKEY: 440 case LDNS_RR_TYPE_NSEC3: 441 case LDNS_RR_TYPE_NSEC3PARAMS: 442 return 0; 443 } 444 return 1; 445} 446 447/** store rrset in buffer in wireformat, return RETVAL_* */ 448static int 449packed_rrset_encode(struct ub_packed_rrset_key* key, sldns_buffer* pkt, 450 uint16_t* num_rrs, time_t timenow, struct regional* region, 451 int do_data, int do_sig, struct compress_tree_node** tree, 452 sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset) 453{ 454 size_t i, j, owner_pos; 455 int r, owner_labs; 456 uint16_t owner_ptr = 0; 457 struct packed_rrset_data* data = (struct packed_rrset_data*) 458 key->entry.data; 459 460 /* does this RR type belong in the answer? */ 461 if(!rrset_belongs_in_reply(s, ntohs(key->rk.type), qtype, dnssec)) 462 return RETVAL_OK; 463 464 owner_labs = dname_count_labels(key->rk.dname); 465 owner_pos = sldns_buffer_position(pkt); 466 467 /* For an rrset with a fixed TTL, use the rrset's TTL as given */ 468 if((key->rk.flags & PACKED_RRSET_FIXEDTTL) != 0) 469 timenow = 0; 470 471 if(do_data) { 472 const sldns_rr_descriptor* c = type_rdata_compressable(key); 473 for(i=0; i<data->count; i++) { 474 /* rrset roundrobin */ 475 j = (i + rr_offset) % data->count; 476 if((r=compress_owner(key, pkt, region, tree, 477 owner_pos, &owner_ptr, owner_labs)) 478 != RETVAL_OK) 479 return r; 480 sldns_buffer_write(pkt, &key->rk.type, 2); 481 sldns_buffer_write(pkt, &key->rk.rrset_class, 2); 482 if(data->rr_ttl[j] < timenow) 483 sldns_buffer_write_u32(pkt, 0); 484 else sldns_buffer_write_u32(pkt, 485 data->rr_ttl[j]-timenow); 486 if(c) { 487 if((r=compress_rdata(pkt, data->rr_data[j], 488 data->rr_len[j], region, tree, c)) 489 != RETVAL_OK) 490 return r; 491 } else { 492 if(sldns_buffer_remaining(pkt) < data->rr_len[j]) 493 return RETVAL_TRUNC; 494 sldns_buffer_write(pkt, data->rr_data[j], 495 data->rr_len[j]); 496 } 497 } 498 } 499 /* insert rrsigs */ 500 if(do_sig && dnssec) { 501 size_t total = data->count+data->rrsig_count; 502 for(i=data->count; i<total; i++) { 503 if(owner_ptr && owner_labs != 1) { 504 if(sldns_buffer_remaining(pkt) < 505 2+4+4+data->rr_len[i]) 506 return RETVAL_TRUNC; 507 sldns_buffer_write(pkt, &owner_ptr, 2); 508 } else { 509 if((r=compress_any_dname(key->rk.dname, 510 pkt, owner_labs, region, tree)) 511 != RETVAL_OK) 512 return r; 513 if(sldns_buffer_remaining(pkt) < 514 4+4+data->rr_len[i]) 515 return RETVAL_TRUNC; 516 } 517 sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_RRSIG); 518 sldns_buffer_write(pkt, &key->rk.rrset_class, 2); 519 if(data->rr_ttl[i] < timenow) 520 sldns_buffer_write_u32(pkt, 0); 521 else sldns_buffer_write_u32(pkt, 522 data->rr_ttl[i]-timenow); 523 /* rrsig rdata cannot be compressed, perform 100+ byte 524 * memcopy. */ 525 sldns_buffer_write(pkt, data->rr_data[i], 526 data->rr_len[i]); 527 } 528 } 529 /* change rrnum only after we are sure it fits */ 530 if(do_data) 531 *num_rrs += data->count; 532 if(do_sig && dnssec) 533 *num_rrs += data->rrsig_count; 534 535 return RETVAL_OK; 536} 537 538/** store msg section in wireformat buffer, return RETVAL_* */ 539static int 540insert_section(struct reply_info* rep, size_t num_rrsets, uint16_t* num_rrs, 541 sldns_buffer* pkt, size_t rrsets_before, time_t timenow, 542 struct regional* region, struct compress_tree_node** tree, 543 sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset) 544{ 545 int r; 546 size_t i, setstart; 547 /* we now allow this function to be called multiple times for the 548 * same section, incrementally updating num_rrs. The caller is 549 * responsible for initializing it (which is the case in the current 550 * implementation). */ 551 552 if(s != LDNS_SECTION_ADDITIONAL) { 553 if(s == LDNS_SECTION_ANSWER && qtype == LDNS_RR_TYPE_ANY) 554 dnssec = 1; /* include all types in ANY answer */ 555 for(i=0; i<num_rrsets; i++) { 556 setstart = sldns_buffer_position(pkt); 557 if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i], 558 pkt, num_rrs, timenow, region, 1, 1, tree, 559 s, qtype, dnssec, rr_offset)) 560 != RETVAL_OK) { 561 /* Bad, but if due to size must set TC bit */ 562 /* trim off the rrset neatly. */ 563 sldns_buffer_set_position(pkt, setstart); 564 return r; 565 } 566 } 567 } else { 568 for(i=0; i<num_rrsets; i++) { 569 setstart = sldns_buffer_position(pkt); 570 if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i], 571 pkt, num_rrs, timenow, region, 1, 0, tree, 572 s, qtype, dnssec, rr_offset)) 573 != RETVAL_OK) { 574 sldns_buffer_set_position(pkt, setstart); 575 return r; 576 } 577 } 578 if(dnssec) 579 for(i=0; i<num_rrsets; i++) { 580 setstart = sldns_buffer_position(pkt); 581 if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i], 582 pkt, num_rrs, timenow, region, 0, 1, tree, 583 s, qtype, dnssec, rr_offset)) 584 != RETVAL_OK) { 585 sldns_buffer_set_position(pkt, setstart); 586 return r; 587 } 588 } 589 } 590 return RETVAL_OK; 591} 592 593/** store query section in wireformat buffer, return RETVAL */ 594static int 595insert_query(struct query_info* qinfo, struct compress_tree_node** tree, 596 sldns_buffer* buffer, struct regional* region) 597{ 598 uint8_t* qname = qinfo->local_alias ? 599 qinfo->local_alias->rrset->rk.dname : qinfo->qname; 600 size_t qname_len = qinfo->local_alias ? 601 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len; 602 if(sldns_buffer_remaining(buffer) < 603 qinfo->qname_len+sizeof(uint16_t)*2) 604 return RETVAL_TRUNC; /* buffer too small */ 605 /* the query is the first name inserted into the tree */ 606 if(!compress_tree_store(qname, dname_count_labels(qname), 607 sldns_buffer_position(buffer), region, NULL, tree)) 608 return RETVAL_OUTMEM; 609 if(sldns_buffer_current(buffer) == qname) 610 sldns_buffer_skip(buffer, (ssize_t)qname_len); 611 else sldns_buffer_write(buffer, qname, qname_len); 612 sldns_buffer_write_u16(buffer, qinfo->qtype); 613 sldns_buffer_write_u16(buffer, qinfo->qclass); 614 return RETVAL_OK; 615} 616 617static int 618positive_answer(struct reply_info* rep, uint16_t qtype) { 619 size_t i; 620 if (FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR) 621 return 0; 622 623 for(i=0;i<rep->an_numrrsets; i++) { 624 if(ntohs(rep->rrsets[i]->rk.type) == qtype) { 625 /* in case it is a wildcard with DNSSEC, there will 626 * be NSEC/NSEC3 records in the authority section 627 * that we cannot remove */ 628 for(i=rep->an_numrrsets; i<rep->an_numrrsets+ 629 rep->ns_numrrsets; i++) { 630 if(ntohs(rep->rrsets[i]->rk.type) == 631 LDNS_RR_TYPE_NSEC || 632 ntohs(rep->rrsets[i]->rk.type) == 633 LDNS_RR_TYPE_NSEC3) 634 return 0; 635 } 636 return 1; 637 } 638 } 639 return 0; 640} 641 642static int 643negative_answer(struct reply_info* rep) { 644 size_t i; 645 int ns_seen = 0; 646 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN) 647 return 1; 648 if(FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR && 649 rep->an_numrrsets != 0) 650 return 0; /* positive */ 651 if(FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR && 652 FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NXDOMAIN) 653 return 0; 654 for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++){ 655 if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_SOA) 656 return 1; 657 if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NS) 658 ns_seen = 1; 659 } 660 if(ns_seen) return 0; /* could be referral, NS, but no SOA */ 661 return 1; 662} 663 664int 665reply_info_encode(struct query_info* qinfo, struct reply_info* rep, 666 uint16_t id, uint16_t flags, sldns_buffer* buffer, time_t timenow, 667 struct regional* region, uint16_t udpsize, int dnssec, int minimise) 668{ 669 uint16_t ancount=0, nscount=0, arcount=0; 670 struct compress_tree_node* tree = 0; 671 int r; 672 size_t rr_offset; 673 674 sldns_buffer_clear(buffer); 675 if(udpsize < sldns_buffer_limit(buffer)) 676 sldns_buffer_set_limit(buffer, udpsize); 677 if(sldns_buffer_remaining(buffer) < LDNS_HEADER_SIZE) 678 return 0; 679 680 sldns_buffer_write(buffer, &id, sizeof(uint16_t)); 681 sldns_buffer_write_u16(buffer, flags); 682 sldns_buffer_write_u16(buffer, rep->qdcount); 683 /* set an, ns, ar counts to zero in case of small packets */ 684 sldns_buffer_write(buffer, "\000\000\000\000\000\000", 6); 685 686 /* insert query section */ 687 if(rep->qdcount) { 688 if((r=insert_query(qinfo, &tree, buffer, region)) != 689 RETVAL_OK) { 690 if(r == RETVAL_TRUNC) { 691 /* create truncated message */ 692 sldns_buffer_write_u16_at(buffer, 4, 0); 693 LDNS_TC_SET(sldns_buffer_begin(buffer)); 694 sldns_buffer_flip(buffer); 695 return 1; 696 } 697 return 0; 698 } 699 } 700 /* roundrobin offset. using query id for random number. With ntohs 701 * for different roundrobins for sequential id client senders. */ 702 rr_offset = RRSET_ROUNDROBIN?ntohs(id)+(timenow?timenow:time(NULL)):0; 703 704 /* "prepend" any local alias records in the answer section if this 705 * response is supposed to be authoritative. Currently it should 706 * be a single CNAME record (sanity-checked in worker_handle_request()) 707 * but it can be extended if and when we support more variations of 708 * aliases. */ 709 if(qinfo->local_alias && (flags & BIT_AA)) { 710 struct reply_info arep; 711 time_t timezero = 0; /* to use the 'authoritative' TTL */ 712 memset(&arep, 0, sizeof(arep)); 713 arep.flags = rep->flags; 714 arep.an_numrrsets = 1; 715 arep.rrset_count = 1; 716 arep.rrsets = &qinfo->local_alias->rrset; 717 if((r=insert_section(&arep, 1, &ancount, buffer, 0, 718 timezero, region, &tree, LDNS_SECTION_ANSWER, 719 qinfo->qtype, dnssec, rr_offset)) != RETVAL_OK) { 720 if(r == RETVAL_TRUNC) { 721 /* create truncated message */ 722 sldns_buffer_write_u16_at(buffer, 6, ancount); 723 LDNS_TC_SET(sldns_buffer_begin(buffer)); 724 sldns_buffer_flip(buffer); 725 return 1; 726 } 727 return 0; 728 } 729 } 730 731 /* insert answer section */ 732 if((r=insert_section(rep, rep->an_numrrsets, &ancount, buffer, 733 0, timenow, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype, 734 dnssec, rr_offset)) != RETVAL_OK) { 735 if(r == RETVAL_TRUNC) { 736 /* create truncated message */ 737 sldns_buffer_write_u16_at(buffer, 6, ancount); 738 LDNS_TC_SET(sldns_buffer_begin(buffer)); 739 sldns_buffer_flip(buffer); 740 return 1; 741 } 742 return 0; 743 } 744 sldns_buffer_write_u16_at(buffer, 6, ancount); 745 746 /* if response is positive answer, auth/add sections are not required */ 747 if( ! (minimise && positive_answer(rep, qinfo->qtype)) ) { 748 /* insert auth section */ 749 if((r=insert_section(rep, rep->ns_numrrsets, &nscount, buffer, 750 rep->an_numrrsets, timenow, region, &tree, 751 LDNS_SECTION_AUTHORITY, qinfo->qtype, 752 dnssec, rr_offset)) != RETVAL_OK) { 753 if(r == RETVAL_TRUNC) { 754 /* create truncated message */ 755 sldns_buffer_write_u16_at(buffer, 8, nscount); 756 LDNS_TC_SET(sldns_buffer_begin(buffer)); 757 sldns_buffer_flip(buffer); 758 return 1; 759 } 760 return 0; 761 } 762 sldns_buffer_write_u16_at(buffer, 8, nscount); 763 764 if(! (minimise && negative_answer(rep))) { 765 /* insert add section */ 766 if((r=insert_section(rep, rep->ar_numrrsets, &arcount, buffer, 767 rep->an_numrrsets + rep->ns_numrrsets, timenow, region, 768 &tree, LDNS_SECTION_ADDITIONAL, qinfo->qtype, 769 dnssec, rr_offset)) != RETVAL_OK) { 770 if(r == RETVAL_TRUNC) { 771 /* no need to set TC bit, this is the additional */ 772 sldns_buffer_write_u16_at(buffer, 10, arcount); 773 sldns_buffer_flip(buffer); 774 return 1; 775 } 776 return 0; 777 } 778 sldns_buffer_write_u16_at(buffer, 10, arcount); 779 } 780 } 781 sldns_buffer_flip(buffer); 782 return 1; 783} 784 785uint16_t 786calc_edns_field_size(struct edns_data* edns) 787{ 788 size_t rdatalen = 0; 789 struct edns_option* opt; 790 if(!edns || !edns->edns_present) 791 return 0; 792 for(opt = edns->opt_list; opt; opt = opt->next) { 793 rdatalen += 4 + opt->opt_len; 794 } 795 /* domain root '.' + type + class + ttl + rdatalen */ 796 return 1 + 2 + 2 + 4 + 2 + rdatalen; 797} 798 799void 800attach_edns_record(sldns_buffer* pkt, struct edns_data* edns) 801{ 802 size_t len; 803 size_t rdatapos; 804 struct edns_option* opt; 805 if(!edns || !edns->edns_present) 806 return; 807 /* inc additional count */ 808 sldns_buffer_write_u16_at(pkt, 10, 809 sldns_buffer_read_u16_at(pkt, 10) + 1); 810 len = sldns_buffer_limit(pkt); 811 sldns_buffer_clear(pkt); 812 sldns_buffer_set_position(pkt, len); 813 /* write EDNS record */ 814 sldns_buffer_write_u8(pkt, 0); /* '.' label */ 815 sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_OPT); /* type */ 816 sldns_buffer_write_u16(pkt, edns->udp_size); /* class */ 817 sldns_buffer_write_u8(pkt, edns->ext_rcode); /* ttl */ 818 sldns_buffer_write_u8(pkt, edns->edns_version); 819 sldns_buffer_write_u16(pkt, edns->bits); 820 rdatapos = sldns_buffer_position(pkt); 821 sldns_buffer_write_u16(pkt, 0); /* rdatalen */ 822 /* write rdata */ 823 for(opt=edns->opt_list; opt; opt=opt->next) { 824 sldns_buffer_write_u16(pkt, opt->opt_code); 825 sldns_buffer_write_u16(pkt, opt->opt_len); 826 if(opt->opt_len != 0) 827 sldns_buffer_write(pkt, opt->opt_data, opt->opt_len); 828 } 829 if(edns->opt_list) 830 sldns_buffer_write_u16_at(pkt, rdatapos, 831 sldns_buffer_position(pkt)-rdatapos-2); 832 sldns_buffer_flip(pkt); 833} 834 835int 836reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep, 837 uint16_t id, uint16_t qflags, sldns_buffer* pkt, time_t timenow, 838 int cached, struct regional* region, uint16_t udpsize, 839 struct edns_data* edns, int dnssec, int secure) 840{ 841 uint16_t flags; 842 unsigned int attach_edns = 0; 843 844 if(!cached || rep->authoritative) { 845 /* original flags, copy RD and CD bits from query. */ 846 flags = rep->flags | (qflags & (BIT_RD|BIT_CD)); 847 } else { 848 /* remove AA bit, copy RD and CD bits from query. */ 849 flags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD)); 850 } 851 if(secure && (dnssec || (qflags&BIT_AD))) 852 flags |= BIT_AD; 853 /* restore AA bit if we have a local alias and the response can be 854 * authoritative. Also clear AD bit if set as the local data is the 855 * primary answer. */ 856 if(qinf->local_alias && 857 (FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NOERROR || 858 FLAGS_GET_RCODE(rep->flags) == LDNS_RCODE_NXDOMAIN)) { 859 flags |= BIT_AA; 860 flags &= ~BIT_AD; 861 } 862 log_assert(flags & BIT_QR); /* QR bit must be on in our replies */ 863 if(udpsize < LDNS_HEADER_SIZE) 864 return 0; 865 if(sldns_buffer_capacity(pkt) < udpsize) 866 udpsize = sldns_buffer_capacity(pkt); 867 if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) { 868 /* packet too small to contain edns, omit it. */ 869 attach_edns = 0; 870 } else { 871 /* reserve space for edns record */ 872 attach_edns = (unsigned int)calc_edns_field_size(edns); 873 udpsize -= attach_edns; 874 } 875 876 if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region, 877 udpsize, dnssec, MINIMAL_RESPONSES)) { 878 log_err("reply encode: out of memory"); 879 return 0; 880 } 881 if(attach_edns && sldns_buffer_capacity(pkt) >= 882 sldns_buffer_limit(pkt)+attach_edns) 883 attach_edns_record(pkt, edns); 884 return 1; 885} 886 887void 888qinfo_query_encode(sldns_buffer* pkt, struct query_info* qinfo) 889{ 890 uint16_t flags = 0; /* QUERY, NOERROR */ 891 const uint8_t* qname = qinfo->local_alias ? 892 qinfo->local_alias->rrset->rk.dname : qinfo->qname; 893 size_t qname_len = qinfo->local_alias ? 894 qinfo->local_alias->rrset->rk.dname_len : qinfo->qname_len; 895 sldns_buffer_clear(pkt); 896 log_assert(sldns_buffer_remaining(pkt) >= 12+255+4/*max query*/); 897 sldns_buffer_skip(pkt, 2); /* id done later */ 898 sldns_buffer_write_u16(pkt, flags); 899 sldns_buffer_write_u16(pkt, 1); /* query count */ 900 sldns_buffer_write(pkt, "\000\000\000\000\000\000", 6); /* counts */ 901 sldns_buffer_write(pkt, qname, qname_len); 902 sldns_buffer_write_u16(pkt, qinfo->qtype); 903 sldns_buffer_write_u16(pkt, qinfo->qclass); 904 sldns_buffer_flip(pkt); 905} 906 907void 908error_encode(sldns_buffer* buf, int r, struct query_info* qinfo, 909 uint16_t qid, uint16_t qflags, struct edns_data* edns) 910{ 911 uint16_t flags; 912 913 sldns_buffer_clear(buf); 914 sldns_buffer_write(buf, &qid, sizeof(uint16_t)); 915 flags = (uint16_t)(BIT_QR | BIT_RA | r); /* QR and retcode*/ 916 flags |= (qflags & (BIT_RD|BIT_CD)); /* copy RD and CD bit */ 917 sldns_buffer_write_u16(buf, flags); 918 if(qinfo) flags = 1; 919 else flags = 0; 920 sldns_buffer_write_u16(buf, flags); 921 flags = 0; 922 sldns_buffer_write(buf, &flags, sizeof(uint16_t)); 923 sldns_buffer_write(buf, &flags, sizeof(uint16_t)); 924 sldns_buffer_write(buf, &flags, sizeof(uint16_t)); 925 if(qinfo) { 926 const uint8_t* qname = qinfo->local_alias ? 927 qinfo->local_alias->rrset->rk.dname : qinfo->qname; 928 size_t qname_len = qinfo->local_alias ? 929 qinfo->local_alias->rrset->rk.dname_len : 930 qinfo->qname_len; 931 if(sldns_buffer_current(buf) == qname) 932 sldns_buffer_skip(buf, (ssize_t)qname_len); 933 else sldns_buffer_write(buf, qname, qname_len); 934 sldns_buffer_write_u16(buf, qinfo->qtype); 935 sldns_buffer_write_u16(buf, qinfo->qclass); 936 } 937 sldns_buffer_flip(buf); 938 if(edns) { 939 struct edns_data es = *edns; 940 es.edns_version = EDNS_ADVERTISED_VERSION; 941 es.udp_size = EDNS_ADVERTISED_SIZE; 942 es.ext_rcode = 0; 943 es.bits &= EDNS_DO; 944 if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) > 945 edns->udp_size) 946 return; 947 attach_edns_record(buf, &es); 948 } 949} 950