contrib/unbound/util/data/msgparse.c

   1 /*
   2  * util/data/msgparse.c - parse wireformat DNS messages.
   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  * \file
  37  * Routines for message parsing a packet buffer to a descriptive structure.
  38  */
  39 #include "config.h"
  40 #include "util/data/msgparse.h"
  41 #include "util/data/dname.h"
  42 #include "util/data/packed_rrset.h"
  43 #include "util/storage/lookup3.h"
  44 #include "util/regional.h"
  45 #include "ldns/rrdef.h"
  46 #include "ldns/sbuffer.h"
  47 #include "ldns/parseutil.h"
  48 #include "ldns/wire2str.h"
  49
  50 /** smart comparison of (compressed, valid) dnames from packet */
  51 static int
  52 smart_compare(sldns_buffer* pkt, uint8_t* dnow,
  53         uint8_t* dprfirst, uint8_t* dprlast)
  54 {
  55         if(LABEL_IS_PTR(*dnow)) {
  56                 /* ptr points to a previous dname */
  57                 uint8_t* p = sldns_buffer_at(pkt, PTR_OFFSET(dnow[0], dnow[1]));
  58                 if( p == dprfirst || p == dprlast )
  59                         return 0;
  60                 /* prev dname is also a ptr, both ptrs are the same. */
  61                 if(LABEL_IS_PTR(*dprlast) &&
  62                         dprlast[0] == dnow[0] && dprlast[1] == dnow[1])
  63                         return 0;
  64         }
  65         return dname_pkt_compare(pkt, dnow, dprlast);
  66 }
  67
  68 /**
  69  * Allocate new rrset in region, fill with data.
  70  */
  71 static struct rrset_parse*
  72 new_rrset(struct msg_parse* msg, uint8_t* dname, size_t dnamelen,
  73         uint16_t type, uint16_t dclass, hashvalue_t hash,
  74         uint32_t rrset_flags, sldns_pkt_section section,
  75         struct regional* region)
  76 {
  77         struct rrset_parse* p = regional_alloc(region, sizeof(*p));
  78         if(!p) return NULL;
  79         p->rrset_bucket_next = msg->hashtable[hash & (PARSE_TABLE_SIZE-1)];
  80         msg->hashtable[hash & (PARSE_TABLE_SIZE-1)] = p;
  81         p->rrset_all_next = 0;
  82         if(msg->rrset_last)
  83                 msg->rrset_last->rrset_all_next = p;
  84         else    msg->rrset_first = p;
  85         msg->rrset_last = p;
  86         p->hash = hash;
  87         p->section = section;
  88         p->dname = dname;
  89         p->dname_len = dnamelen;
  90         p->type = type;
  91         p->rrset_class = dclass;
  92         p->flags = rrset_flags;
  93         p->rr_count = 0;
  94         p->size = 0;
  95         p->rr_first = 0;
  96         p->rr_last = 0;
  97         p->rrsig_count = 0;
  98         p->rrsig_first = 0;
  99         p->rrsig_last = 0;
 100         return p;
 101 }
 102
 103 /** See if next rrset is nsec at zone apex */
 104 static int
 105 nsec_at_apex(sldns_buffer* pkt)
 106 {
 107         /* we are at ttl position in packet. */
 108         size_t pos = sldns_buffer_position(pkt);
 109         uint16_t rdatalen;
 110         if(sldns_buffer_remaining(pkt) < 7) /* ttl+len+root */
 111                 return 0; /* eek! */
 112         sldns_buffer_skip(pkt, 4); /* ttl */;
 113         rdatalen = sldns_buffer_read_u16(pkt);
 114         if(sldns_buffer_remaining(pkt) < rdatalen) {
 115                 sldns_buffer_set_position(pkt, pos);
 116                 return 0; /* parse error happens later */
 117         }
 118         /* must validate the nsec next domain name format */
 119         if(pkt_dname_len(pkt) == 0) {
 120                 sldns_buffer_set_position(pkt, pos);
 121                 return 0; /* parse error */
 122         }
 123
 124         /* see if SOA bit is set. */
 125         if(sldns_buffer_position(pkt) < pos+4+rdatalen) {
 126                 /* nsec type bitmap contains items */
 127                 uint8_t win, blen, bits;
 128                 /* need: windownum, bitmap len, firstbyte */
 129                 if(sldns_buffer_position(pkt)+3 > pos+4+rdatalen) {
 130                         sldns_buffer_set_position(pkt, pos);
 131                         return 0; /* malformed nsec */
 132                 }
 133                 win = sldns_buffer_read_u8(pkt);
 134                 blen = sldns_buffer_read_u8(pkt);
 135                 bits = sldns_buffer_read_u8(pkt);
 136                 /* 0window always first window. bitlen >=1 or parse
 137                    error really. bit 0x2 is SOA. */
 138                 if(win == 0 && blen >= 1 && (bits & 0x02)) {
 139                         sldns_buffer_set_position(pkt, pos);
 140                         return 1;
 141                 }
 142         }
 143
 144         sldns_buffer_set_position(pkt, pos);
 145         return 0;
 146 }
 147
 148 /** Calculate rrset flags */
 149 static uint32_t
 150 pkt_rrset_flags(sldns_buffer* pkt, uint16_t type, sldns_pkt_section sec)
 151 {
 152         uint32_t f = 0;
 153         if(type == LDNS_RR_TYPE_NSEC && nsec_at_apex(pkt)) {
 154                 f |= PACKED_RRSET_NSEC_AT_APEX;
 155         } else if(type == LDNS_RR_TYPE_SOA && sec == LDNS_SECTION_AUTHORITY) {
 156                 f |= PACKED_RRSET_SOA_NEG;
 157         }
 158         return f;
 159 }
 160
 161 hashvalue_t
 162 pkt_hash_rrset(sldns_buffer* pkt, uint8_t* dname, uint16_t type,
 163         uint16_t dclass, uint32_t rrset_flags)
 164 {
 165         /* note this MUST be identical to rrset_key_hash in packed_rrset.c */
 166         /* this routine handles compressed names */
 167         hashvalue_t h = 0xab;
 168         h = dname_pkt_hash(pkt, dname, h);
 169         h = hashlittle(&type, sizeof(type), h);         /* host order */
 170         h = hashlittle(&dclass, sizeof(dclass), h);     /* netw order */
 171         h = hashlittle(&rrset_flags, sizeof(uint32_t), h);
 172         return h;
 173 }
 174
 175 /** create partial dname hash for rrset hash */
 176 static hashvalue_t
 177 pkt_hash_rrset_first(sldns_buffer* pkt, uint8_t* dname)
 178 {
 179         /* works together with pkt_hash_rrset_rest */
 180         /* note this MUST be identical to rrset_key_hash in packed_rrset.c */
 181         /* this routine handles compressed names */
 182         hashvalue_t h = 0xab;
 183         h = dname_pkt_hash(pkt, dname, h);
 184         return h;
 185 }
 186
 187 /** create a rrset hash from a partial dname hash */
 188 static hashvalue_t
 189 pkt_hash_rrset_rest(hashvalue_t dname_h, uint16_t type, uint16_t dclass,
 190         uint32_t rrset_flags)
 191 {
 192         /* works together with pkt_hash_rrset_first */
 193         /* note this MUST be identical to rrset_key_hash in packed_rrset.c */
 194         hashvalue_t h;
 195         h = hashlittle(&type, sizeof(type), dname_h);   /* host order */
 196         h = hashlittle(&dclass, sizeof(dclass), h);     /* netw order */
 197         h = hashlittle(&rrset_flags, sizeof(uint32_t), h);
 198         return h;
 199 }
 200
 201 /** compare rrset_parse with data */
 202 static int
 203 rrset_parse_equals(struct rrset_parse* p, sldns_buffer* pkt, hashvalue_t h,
 204         uint32_t rrset_flags, uint8_t* dname, size_t dnamelen,
 205         uint16_t type, uint16_t dclass)
 206 {
 207         if(p->hash == h && p->dname_len == dnamelen && p->type == type &&
 208                 p->rrset_class == dclass && p->flags == rrset_flags &&
 209                 dname_pkt_compare(pkt, dname, p->dname) == 0)
 210                 return 1;
 211         return 0;
 212 }
 213
 214
 215 struct rrset_parse*
 216 msgparse_hashtable_lookup(struct msg_parse* msg, sldns_buffer* pkt,
 217         hashvalue_t h, uint32_t rrset_flags, uint8_t* dname, size_t dnamelen,
 218         uint16_t type, uint16_t dclass)
 219 {
 220         struct rrset_parse* p = msg->hashtable[h & (PARSE_TABLE_SIZE-1)];
 221         while(p) {
 222                 if(rrset_parse_equals(p, pkt, h, rrset_flags, dname, dnamelen,
 223                         type, dclass))
 224                         return p;
 225                 p = p->rrset_bucket_next;
 226         }
 227         return NULL;
 228 }
 229
 230 /** return type networkformat that rrsig in packet covers */
 231 static int
 232 pkt_rrsig_covered(sldns_buffer* pkt, uint8_t* here, uint16_t* type)
 233 {
 234         size_t pos = sldns_buffer_position(pkt);
 235         sldns_buffer_set_position(pkt, (size_t)(here-sldns_buffer_begin(pkt)));
 236         /* ttl + len + size of small rrsig(rootlabel, no signature) */
 237         if(sldns_buffer_remaining(pkt) < 4+2+19)
 238                 return 0;
 239         sldns_buffer_skip(pkt, 4); /* ttl */
 240         if(sldns_buffer_read_u16(pkt) < 19) /* too short */ {
 241                 sldns_buffer_set_position(pkt, pos);
 242                 return 0;
 243         }
 244         *type = sldns_buffer_read_u16(pkt);
 245         sldns_buffer_set_position(pkt, pos);
 246         return 1;
 247 }
 248
 249 /** true if covered type equals prevtype */
 250 static int
 251 pkt_rrsig_covered_equals(sldns_buffer* pkt, uint8_t* here, uint16_t type)
 252 {
 253         uint16_t t;
 254         if(pkt_rrsig_covered(pkt, here, &t) && t == type)
 255                 return 1;
 256         return 0;
 257 }
 258
 259 void
 260 msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset)
 261 {
 262         struct rrset_parse** p;
 263         p = &msg->hashtable[ rrset->hash & (PARSE_TABLE_SIZE-1) ];
 264         while(*p) {
 265                 if(*p == rrset) {
 266                         *p = rrset->rrset_bucket_next;
 267                         return;
 268                 }
 269                 p = &( (*p)->rrset_bucket_next );
 270         }
 271 }
 272
 273 /** change section of rrset from previous to current section */
 274 static void
 275 change_section(struct msg_parse* msg, struct rrset_parse* rrset,
 276         sldns_pkt_section section)
 277 {
 278         struct rrset_parse *p, *prev;
 279         /* remove from list */
 280         if(section == rrset->section)
 281                 return;
 282         p = msg->rrset_first;
 283         prev = 0;
 284         while(p) {
 285                 if(p == rrset) {
 286                         if(prev) prev->rrset_all_next = p->rrset_all_next;
 287                         else    msg->rrset_first = p->rrset_all_next;
 288                         if(msg->rrset_last == rrset)
 289                                 msg->rrset_last = prev;
 290                         break;
 291                 }
 292                 prev = p;
 293                 p = p->rrset_all_next;
 294         }
 295         /* remove from count */
 296         switch(rrset->section) {
 297                 case LDNS_SECTION_ANSWER: msg->an_rrsets--; break;
 298                 case LDNS_SECTION_AUTHORITY: msg->ns_rrsets--; break;
 299                 case LDNS_SECTION_ADDITIONAL: msg->ar_rrsets--; break;
 300                 default: log_assert(0);
 301         }
 302         /* insert at end of list */
 303         rrset->rrset_all_next = 0;
 304         if(msg->rrset_last)
 305                 msg->rrset_last->rrset_all_next = rrset;
 306         else    msg->rrset_first = rrset;
 307         msg->rrset_last = rrset;
 308         /* up count of new section */
 309         switch(section) {
 310                 case LDNS_SECTION_AUTHORITY: msg->ns_rrsets++; break;
 311                 case LDNS_SECTION_ADDITIONAL: msg->ar_rrsets++; break;
 312                 default: log_assert(0);
 313         }
 314         rrset->section = section;
 315 }
 316
 317 /** see if rrset of type RRSIG contains sig over given type */
 318 static int
 319 rrset_has_sigover(sldns_buffer* pkt, struct rrset_parse* rrset, uint16_t type,
 320         int* hasother)
 321 {
 322         int res = 0;
 323         struct rr_parse* rr = rrset->rr_first;
 324         log_assert( rrset->type == LDNS_RR_TYPE_RRSIG );
 325         while(rr) {
 326                 if(pkt_rrsig_covered_equals(pkt, rr->ttl_data, type))
 327                         res = 1;
 328                 else    *hasother = 1;
 329                 rr = rr->next;
 330         }
 331         return res;
 332 }
 333
 334 /** move rrsigs from sigset to dataset */
 335 static int
 336 moveover_rrsigs(sldns_buffer* pkt, struct regional* region,
 337         struct rrset_parse* sigset, struct rrset_parse* dataset, int duplicate)
 338 {
 339         struct rr_parse* sig = sigset->rr_first;
 340         struct rr_parse* prev = NULL;
 341         struct rr_parse* insert;
 342         struct rr_parse* nextsig;
 343         while(sig) {
 344                 nextsig = sig->next;
 345                 if(pkt_rrsig_covered_equals(pkt, sig->ttl_data,
 346                         dataset->type)) {
 347                         if(duplicate) {
 348                                 /* new */
 349                                 insert = (struct rr_parse*)regional_alloc(
 350                                         region, sizeof(struct rr_parse));
 351                                 if(!insert) return 0;
 352                                 insert->outside_packet = 0;
 353                                 insert->ttl_data = sig->ttl_data;
 354                                 insert->size = sig->size;
 355                                 /* prev not used */
 356                         } else {
 357                                 /* remove from sigset */
 358                                 if(prev) prev->next = sig->next;
 359                                 else    sigset->rr_first = sig->next;
 360                                 if(sigset->rr_last == sig)
 361                                         sigset->rr_last = prev;
 362                                 sigset->rr_count--;
 363                                 sigset->size -= sig->size;
 364                                 insert = sig;
 365                                 /* prev not changed */
 366                         }
 367                         /* add to dataset */
 368                         dataset->rrsig_count++;
 369                         insert->next = 0;
 370                         if(dataset->rrsig_last)
 371                                 dataset->rrsig_last->next = insert;
 372                         else    dataset->rrsig_first = insert;
 373                         dataset->rrsig_last = insert;
 374                         dataset->size += insert->size;
 375                 } else  {
 376                         prev = sig;
 377                 }
 378                 sig = nextsig;
 379         }
 380         return 1;
 381 }
 382
 383 /** change an rrsig rrset for use as data rrset */
 384 static struct rrset_parse*
 385 change_rrsig_rrset(struct rrset_parse* sigset, struct msg_parse* msg,
 386         sldns_buffer* pkt, uint16_t datatype, uint32_t rrset_flags,
 387         int hasother, sldns_pkt_section section, struct regional* region)
 388 {
 389         struct rrset_parse* dataset = sigset;
 390         hashvalue_t hash = pkt_hash_rrset(pkt, sigset->dname, datatype,
 391                 sigset->rrset_class, rrset_flags);
 392         log_assert( sigset->type == LDNS_RR_TYPE_RRSIG );
 393         log_assert( datatype != LDNS_RR_TYPE_RRSIG );
 394         if(hasother) {
 395                 /* need to make new rrset to hold data type */
 396                 dataset = new_rrset(msg, sigset->dname, sigset->dname_len,
 397                         datatype, sigset->rrset_class, hash, rrset_flags,
 398                         section, region);
 399                 if(!dataset)
 400                         return NULL;
 401                 switch(section) {
 402                         case LDNS_SECTION_ANSWER: msg->an_rrsets++; break;
 403                         case LDNS_SECTION_AUTHORITY: msg->ns_rrsets++; break;
 404                         case LDNS_SECTION_ADDITIONAL: msg->ar_rrsets++; break;
 405                         default: log_assert(0);
 406                 }
 407                 if(!moveover_rrsigs(pkt, region, sigset, dataset,
 408                         msg->qtype == LDNS_RR_TYPE_RRSIG ||
 409                         (msg->qtype == LDNS_RR_TYPE_ANY &&
 410                         section != LDNS_SECTION_ANSWER) ))
 411                         return NULL;
 412                 return dataset;
 413         }
 414         /* changeover the type of the rrset to data set */
 415         msgparse_bucket_remove(msg, dataset);
 416         /* insert into new hash bucket */
 417         dataset->rrset_bucket_next = msg->hashtable[hash&(PARSE_TABLE_SIZE-1)];
 418         msg->hashtable[hash&(PARSE_TABLE_SIZE-1)] = dataset;
 419         dataset->hash = hash;
 420         /* use section of data item for result */
 421         change_section(msg, dataset, section);
 422         dataset->type = datatype;
 423         dataset->flags = rrset_flags;
 424         dataset->rrsig_count += dataset->rr_count;
 425         dataset->rr_count = 0;
 426         /* move sigs to end of siglist */
 427         if(dataset->rrsig_last)
 428                 dataset->rrsig_last->next = dataset->rr_first;
 429         else    dataset->rrsig_first = dataset->rr_first;
 430         dataset->rrsig_last = dataset->rr_last;
 431         dataset->rr_first = 0;
 432         dataset->rr_last = 0;
 433         return dataset;
 434 }
 435
 436 /** Find rrset. If equal to previous it is fast. hash if not so.
 437  * @param msg: the message with hash table.
 438  * @param pkt: the packet in wireformat (needed for compression ptrs).
 439  * @param dname: pointer to start of dname (compressed) in packet.
 440  * @param dnamelen: uncompressed wirefmt length of dname.
 441  * @param type: type of current rr.
 442  * @param dclass: class of current rr.
 443  * @param hash: hash value is returned if the rrset could not be found.
 444  * @param rrset_flags: is returned if the rrset could not be found.
 445  * @param prev_dname_first: dname of last seen RR. First seen dname.
 446  * @param prev_dname_last: dname of last seen RR. Last seen dname.
 447  * @param prev_dnamelen: dname len of last seen RR.
 448  * @param prev_type: type of last seen RR.
 449  * @param prev_dclass: class of last seen RR.
 450  * @param rrset_prev: last seen RRset.
 451  * @param section: the current section in the packet.
 452  * @param region: used to allocate temporary parsing data.
 453  * @return 0 on out of memory.
 454  */
 455 static int
 456 find_rrset(struct msg_parse* msg, sldns_buffer* pkt, uint8_t* dname,
 457         size_t dnamelen, uint16_t type, uint16_t dclass, hashvalue_t* hash,
 458         uint32_t* rrset_flags,
 459         uint8_t** prev_dname_first, uint8_t** prev_dname_last,
 460         size_t* prev_dnamelen, uint16_t* prev_type,
 461         uint16_t* prev_dclass, struct rrset_parse** rrset_prev,
 462         sldns_pkt_section section, struct regional* region)
 463 {
 464         hashvalue_t dname_h = pkt_hash_rrset_first(pkt, dname);
 465         uint16_t covtype;
 466         if(*rrset_prev) {
 467                 /* check if equal to previous item */
 468                 if(type == *prev_type && dclass == *prev_dclass &&
 469                         dnamelen == *prev_dnamelen &&
 470                         smart_compare(pkt, dname, *prev_dname_first,
 471                                 *prev_dname_last) == 0 &&
 472                         type != LDNS_RR_TYPE_RRSIG) {
 473                         /* same as previous */
 474                         *prev_dname_last = dname;
 475                         return 1;
 476                 }
 477                 /* check if rrsig over previous item */
 478                 if(type == LDNS_RR_TYPE_RRSIG && dclass == *prev_dclass &&
 479                         pkt_rrsig_covered_equals(pkt, sldns_buffer_current(pkt),
 480                                 *prev_type) &&
 481                         smart_compare(pkt, dname, *prev_dname_first,
 482                                 *prev_dname_last) == 0) {
 483                         /* covers previous */
 484                         *prev_dname_last = dname;
 485                         return 1;
 486                 }
 487         }
 488         /* find by hashing and lookup in hashtable */
 489         *rrset_flags = pkt_rrset_flags(pkt, type, section);
 490
 491         /* if rrsig - try to lookup matching data set first */
 492         if(type == LDNS_RR_TYPE_RRSIG && pkt_rrsig_covered(pkt,
 493                 sldns_buffer_current(pkt), &covtype)) {
 494                 *hash = pkt_hash_rrset_rest(dname_h, covtype, dclass,
 495                         *rrset_flags);
 496                 *rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash,
 497                         *rrset_flags, dname, dnamelen, covtype, dclass);
 498                 if(!*rrset_prev && covtype == LDNS_RR_TYPE_NSEC) {
 499                         /* if NSEC try with NSEC apex bit twiddled */
 500                         *rrset_flags ^= PACKED_RRSET_NSEC_AT_APEX;
 501                         *hash = pkt_hash_rrset_rest(dname_h, covtype, dclass,
 502                                 *rrset_flags);
 503                         *rrset_prev = msgparse_hashtable_lookup(msg, pkt,
 504                                 *hash, *rrset_flags, dname, dnamelen, covtype,
 505                                 dclass);
 506                         if(!*rrset_prev) /* untwiddle if not found */
 507                                 *rrset_flags ^= PACKED_RRSET_NSEC_AT_APEX;
 508                 }
 509                 if(!*rrset_prev && covtype == LDNS_RR_TYPE_SOA) {
 510                         /* if SOA try with SOA neg flag twiddled */
 511                         *rrset_flags ^= PACKED_RRSET_SOA_NEG;
 512                         *hash = pkt_hash_rrset_rest(dname_h, covtype, dclass,
 513                                 *rrset_flags);
 514                         *rrset_prev = msgparse_hashtable_lookup(msg, pkt,
 515                                 *hash, *rrset_flags, dname, dnamelen, covtype,
 516                                 dclass);
 517                         if(!*rrset_prev) /* untwiddle if not found */
 518                                 *rrset_flags ^= PACKED_RRSET_SOA_NEG;
 519                 }
 520                 if(*rrset_prev) {
 521                         *prev_dname_first = (*rrset_prev)->dname;
 522                         *prev_dname_last = dname;
 523                         *prev_dnamelen = dnamelen;
 524                         *prev_type = covtype;
 525                         *prev_dclass = dclass;
 526                         return 1;
 527                 }
 528         }
 529         if(type != LDNS_RR_TYPE_RRSIG) {
 530                 int hasother = 0;
 531                 /* find matching rrsig */
 532                 *hash = pkt_hash_rrset_rest(dname_h, LDNS_RR_TYPE_RRSIG,
 533                         dclass, 0);
 534                 *rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash,
 535                         0, dname, dnamelen, LDNS_RR_TYPE_RRSIG,
 536                         dclass);
 537                 if(*rrset_prev && rrset_has_sigover(pkt, *rrset_prev, type,
 538                         &hasother)) {
 539                         /* yes! */
 540                         *prev_dname_first = (*rrset_prev)->dname;
 541                         *prev_dname_last = dname;
 542                         *prev_dnamelen = dnamelen;
 543                         *prev_type = type;
 544                         *prev_dclass = dclass;
 545                         *rrset_prev = change_rrsig_rrset(*rrset_prev, msg,
 546                                 pkt, type, *rrset_flags, hasother, section,
 547                                 region);
 548                         if(!*rrset_prev) return 0;
 549                         return 1;
 550                 }
 551         }
 552
 553         *hash = pkt_hash_rrset_rest(dname_h, type, dclass, *rrset_flags);
 554         *rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash, *rrset_flags,
 555                 dname, dnamelen, type, dclass);
 556         if(*rrset_prev)
 557                 *prev_dname_first = (*rrset_prev)->dname;
 558         else    *prev_dname_first = dname;
 559         *prev_dname_last = dname;
 560         *prev_dnamelen = dnamelen;
 561         *prev_type = type;
 562         *prev_dclass = dclass;
 563         return 1;
 564 }
 565
 566 /**
 567  * Parse query section.
 568  * @param pkt: packet, position at call must be at start of query section.
 569  *      at end position is after query section.
 570  * @param msg: store results here.
 571  * @return: 0 if OK, or rcode on error.
 572  */
 573 static int
 574 parse_query_section(sldns_buffer* pkt, struct msg_parse* msg)
 575 {
 576         if(msg->qdcount == 0)
 577                 return 0;
 578         if(msg->qdcount > 1)
 579                 return LDNS_RCODE_FORMERR;
 580         log_assert(msg->qdcount == 1);
 581         if(sldns_buffer_remaining(pkt) <= 0)
 582                 return LDNS_RCODE_FORMERR;
 583         msg->qname = sldns_buffer_current(pkt);
 584         if((msg->qname_len = pkt_dname_len(pkt)) == 0)
 585                 return LDNS_RCODE_FORMERR;
 586         if(sldns_buffer_remaining(pkt) < sizeof(uint16_t)*2)
 587                 return LDNS_RCODE_FORMERR;
 588         msg->qtype = sldns_buffer_read_u16(pkt);
 589         msg->qclass = sldns_buffer_read_u16(pkt);
 590         return 0;
 591 }
 592
 593 size_t
 594 get_rdf_size(sldns_rdf_type rdf)
 595 {
 596         switch(rdf) {
 597                 case LDNS_RDF_TYPE_CLASS:
 598                 case LDNS_RDF_TYPE_ALG:
 599                 case LDNS_RDF_TYPE_INT8:
 600                         return 1;
 601                         break;
 602                 case LDNS_RDF_TYPE_INT16:
 603                 case LDNS_RDF_TYPE_TYPE:
 604                 case LDNS_RDF_TYPE_CERT_ALG:
 605                         return 2;
 606                         break;
 607                 case LDNS_RDF_TYPE_INT32:
 608                 case LDNS_RDF_TYPE_TIME:
 609                 case LDNS_RDF_TYPE_A:
 610                 case LDNS_RDF_TYPE_PERIOD:
 611                         return 4;
 612                         break;
 613                 case LDNS_RDF_TYPE_TSIGTIME:
 614                         return 6;
 615                         break;
 616                 case LDNS_RDF_TYPE_AAAA:
 617                         return 16;
 618                         break;
 619                 default:
 620                         log_assert(0); /* add type above */
 621                         /* only types that appear before a domain  *
 622                          * name are needed. rest is simply copied. */
 623         }
 624         return 0;
 625 }
 626
 627 /** calculate the size of one rr */
 628 static int
 629 calc_size(sldns_buffer* pkt, uint16_t type, struct rr_parse* rr)
 630 {
 631         const sldns_rr_descriptor* desc;
 632         uint16_t pkt_len; /* length of rr inside the packet */
 633         rr->size = sizeof(uint16_t); /* the rdatalen */
 634         sldns_buffer_skip(pkt, 4); /* skip ttl */
 635         pkt_len = sldns_buffer_read_u16(pkt);
 636         if(sldns_buffer_remaining(pkt) < pkt_len)
 637                 return 0;
 638         desc = sldns_rr_descript(type);
 639         if(pkt_len > 0 && desc && desc->_dname_count > 0) {
 640                 int count = (int)desc->_dname_count;
 641                 int rdf = 0;
 642                 size_t len;
 643                 size_t oldpos;
 644                 /* skip first part. */
 645                 while(pkt_len > 0 && count) {
 646                         switch(desc->_wireformat[rdf]) {
 647                         case LDNS_RDF_TYPE_DNAME:
 648                                 /* decompress every domain name */
 649                                 oldpos = sldns_buffer_position(pkt);
 650                                 if((len = pkt_dname_len(pkt)) == 0)
 651                                         return 0; /* malformed dname */
 652                                 if(sldns_buffer_position(pkt)-oldpos > pkt_len)
 653                                         return 0; /* dname exceeds rdata */
 654                                 pkt_len -= sldns_buffer_position(pkt)-oldpos;
 655                                 rr->size += len;
 656                                 count--;
 657                                 len = 0;
 658                                 break;
 659                         case LDNS_RDF_TYPE_STR:
 660                                 if(pkt_len < 1) {
 661                                         /* NOTREACHED, due to 'while(>0)' */
 662                                         return 0; /* len byte exceeds rdata */
 663                                 }
 664                                 len = sldns_buffer_current(pkt)[0] + 1;
 665                                 break;
 666                         default:
 667                                 len = get_rdf_size(desc->_wireformat[rdf]);
 668                         }
 669                         if(len) {
 670                                 if(pkt_len < len)
 671                                         return 0; /* exceeds rdata */
 672                                 pkt_len -= len;
 673                                 sldns_buffer_skip(pkt, (ssize_t)len);
 674                                 rr->size += len;
 675                         }
 676                         rdf++;
 677                 }
 678         }
 679         /* remaining rdata */
 680         rr->size += pkt_len;
 681         sldns_buffer_skip(pkt, (ssize_t)pkt_len);
 682         return 1;
 683 }
 684
 685 /** skip rr ttl and rdata */
 686 static int
 687 skip_ttl_rdata(sldns_buffer* pkt)
 688 {
 689         uint16_t rdatalen;
 690         if(sldns_buffer_remaining(pkt) < 6) /* ttl + rdatalen */
 691                 return 0;
 692         sldns_buffer_skip(pkt, 4); /* ttl */
 693         rdatalen = sldns_buffer_read_u16(pkt);
 694         if(sldns_buffer_remaining(pkt) < rdatalen)
 695                 return 0;
 696         sldns_buffer_skip(pkt, (ssize_t)rdatalen);
 697         return 1;
 698 }
 699
 700 /** see if RRSIG is a duplicate of another */
 701 static int
 702 sig_is_double(sldns_buffer* pkt, struct rrset_parse* rrset, uint8_t* ttldata)
 703 {
 704         uint16_t rlen, siglen;
 705         size_t pos = sldns_buffer_position(pkt);
 706         struct rr_parse* sig;
 707         if(sldns_buffer_remaining(pkt) < 6)
 708                 return 0;
 709         sldns_buffer_skip(pkt, 4); /* ttl */
 710         rlen = sldns_buffer_read_u16(pkt);
 711         if(sldns_buffer_remaining(pkt) < rlen) {
 712                 sldns_buffer_set_position(pkt, pos);
 713                 return 0;
 714         }
 715         sldns_buffer_set_position(pkt, pos);
 716
 717         sig = rrset->rrsig_first;
 718         while(sig) {
 719                 /* check if rdatalen is same */
 720                 memmove(&siglen, sig->ttl_data+4, sizeof(siglen));
 721                 siglen = ntohs(siglen);
 722                 /* checks if data in packet is exactly the same, this means
 723                  * also dname in rdata is the same, but rrsig is not allowed
 724                  * to have compressed dnames anyway. If it is compressed anyway
 725                  * it will lead to duplicate rrs for qtype=RRSIG. (or ANY).
 726                  *
 727                  * Cannot use sig->size because size of the other one is not
 728                  * calculated yet.
 729                  */
 730                 if(siglen == rlen) {
 731                         if(siglen>0 && memcmp(sig->ttl_data+6, ttldata+6,
 732                                 siglen) == 0) {
 733                                 /* same! */
 734                                 return 1;
 735                         }
 736                 }
 737                 sig = sig->next;
 738         }
 739         return 0;
 740 }
 741
 742 /** Add rr (from packet here) to rrset, skips rr */
 743 static int
 744 add_rr_to_rrset(struct rrset_parse* rrset, sldns_buffer* pkt,
 745         struct msg_parse* msg, struct regional* region,
 746         sldns_pkt_section section, uint16_t type)
 747 {
 748         struct rr_parse* rr;
 749         /* check section of rrset. */
 750         if(rrset->section != section && type != LDNS_RR_TYPE_RRSIG &&
 751                 rrset->type != LDNS_RR_TYPE_RRSIG) {
 752                 /* silently drop it - we drop the last part, since
 753                  * trust in rr data depends on the section it is in.
 754                  * the less trustworthy part is discarded.
 755                  * also the last part is more likely to be incomplete.
 756                  * RFC 2181: must put RRset only once in response. */
 757                 /*
 758                 verbose(VERB_QUERY, "Packet contains rrset data in "
 759                         "multiple sections, dropped last part.");
 760                 log_buf(VERB_QUERY, "packet was", pkt);
 761                 */
 762                 /* forwards */
 763                 if(!skip_ttl_rdata(pkt))
 764                         return LDNS_RCODE_FORMERR;
 765                 return 0;
 766         }
 767
 768         if( (msg->qtype == LDNS_RR_TYPE_RRSIG ||
 769              msg->qtype == LDNS_RR_TYPE_ANY)
 770             && sig_is_double(pkt, rrset, sldns_buffer_current(pkt))) {
 771                 if(!skip_ttl_rdata(pkt))
 772                         return LDNS_RCODE_FORMERR;
 773                 return 0;
 774         }
 775
 776         /* create rr */
 777         if(!(rr = (struct rr_parse*)regional_alloc(region, sizeof(*rr))))
 778                 return LDNS_RCODE_SERVFAIL;
 779         rr->outside_packet = 0;
 780         rr->ttl_data = sldns_buffer_current(pkt);
 781         rr->next = 0;
 782         if(type == LDNS_RR_TYPE_RRSIG && rrset->type != LDNS_RR_TYPE_RRSIG) {
 783                 if(rrset->rrsig_last)
 784                         rrset->rrsig_last->next = rr;
 785                 else    rrset->rrsig_first = rr;
 786                 rrset->rrsig_last = rr;
 787                 rrset->rrsig_count++;
 788         } else {
 789                 if(rrset->rr_last)
 790                         rrset->rr_last->next = rr;
 791                 else    rrset->rr_first = rr;
 792                 rrset->rr_last = rr;
 793                 rrset->rr_count++;
 794         }
 795
 796         /* calc decompressed size */
 797         if(!calc_size(pkt, type, rr))
 798                 return LDNS_RCODE_FORMERR;
 799         rrset->size += rr->size;
 800
 801         return 0;
 802 }
 803
 804 /**
 805  * Parse packet RR section, for answer, authority and additional sections.
 806  * @param pkt: packet, position at call must be at start of section.
 807  *      at end position is after section.
 808  * @param msg: store results here.
 809  * @param region: how to alloc results.
 810  * @param section: section enum.
 811  * @param num_rrs: how many rrs are in the section.
 812  * @param num_rrsets: returns number of rrsets in the section.
 813  * @return: 0 if OK, or rcode on error.
 814  */
 815 static int
 816 parse_section(sldns_buffer* pkt, struct msg_parse* msg,
 817         struct regional* region, sldns_pkt_section section,
 818         uint16_t num_rrs, size_t* num_rrsets)
 819 {
 820         uint16_t i;
 821         uint8_t* dname, *prev_dname_f = NULL, *prev_dname_l = NULL;
 822         size_t dnamelen, prev_dnamelen = 0;
 823         uint16_t type, prev_type = 0;
 824         uint16_t dclass, prev_dclass = 0;
 825         uint32_t rrset_flags = 0;
 826         hashvalue_t hash = 0;
 827         struct rrset_parse* rrset = NULL;
 828         int r;
 829
 830         if(num_rrs == 0)
 831                 return 0;
 832         if(sldns_buffer_remaining(pkt) <= 0)
 833                 return LDNS_RCODE_FORMERR;
 834         for(i=0; i<num_rrs; i++) {
 835                 /* parse this RR. */
 836                 dname = sldns_buffer_current(pkt);
 837                 if((dnamelen = pkt_dname_len(pkt)) == 0)
 838                         return LDNS_RCODE_FORMERR;
 839                 if(sldns_buffer_remaining(pkt) < 10) /* type, class, ttl, len */
 840                         return LDNS_RCODE_FORMERR;
 841                 type = sldns_buffer_read_u16(pkt);
 842                 sldns_buffer_read(pkt, &dclass, sizeof(dclass));
 843
 844                 if(0) { /* debug show what is being parsed. */
 845                         if(type == LDNS_RR_TYPE_RRSIG) {
 846                                 uint16_t t;
 847                                 if(pkt_rrsig_covered(pkt,
 848                                         sldns_buffer_current(pkt), &t))
 849                                         fprintf(stderr, "parse of %s(%d) [%s(%d)]",
 850                                         sldns_rr_descript(type)?
 851                                         sldns_rr_descript(type)->_name: "??",
 852                                         (int)type,
 853                                         sldns_rr_descript(t)?
 854                                         sldns_rr_descript(t)->_name: "??",
 855                                         (int)t);
 856                         } else
 857                           fprintf(stderr, "parse of %s(%d)",
 858                                 sldns_rr_descript(type)?
 859                                 sldns_rr_descript(type)->_name: "??",
 860                                 (int)type);
 861                         fprintf(stderr, " %s(%d) ",
 862                                 sldns_lookup_by_id(sldns_rr_classes,
 863                                 (int)ntohs(dclass))?sldns_lookup_by_id(
 864                                 sldns_rr_classes, (int)ntohs(dclass))->name:
 865                                 "??", (int)ntohs(dclass));
 866                         dname_print(stderr, pkt, dname);
 867                         fprintf(stderr, "\n");
 868                 }
 869
 870                 /* see if it is part of an existing RR set */
 871                 if(!find_rrset(msg, pkt, dname, dnamelen, type, dclass, &hash,
 872                         &rrset_flags, &prev_dname_f, &prev_dname_l,
 873                         &prev_dnamelen, &prev_type, &prev_dclass, &rrset,
 874                         section, region))
 875                         return LDNS_RCODE_SERVFAIL;
 876                 if(!rrset) {
 877                         /* it is a new RR set. hash&flags already calculated.*/
 878                         (*num_rrsets)++;
 879                         rrset = new_rrset(msg, dname, dnamelen, type, dclass,
 880                                 hash, rrset_flags, section, region);
 881                         if(!rrset)
 882                                 return LDNS_RCODE_SERVFAIL;
 883                 }
 884                 else if(0)      {
 885                         fprintf(stderr, "is part of existing: ");
 886                         dname_print(stderr, pkt, rrset->dname);
 887                         fprintf(stderr, " type %s(%d)\n",
 888                                 sldns_rr_descript(rrset->type)?
 889                                 sldns_rr_descript(rrset->type)->_name: "??",
 890                                 (int)rrset->type);
 891                 }
 892                 /* add to rrset. */
 893                 if((r=add_rr_to_rrset(rrset, pkt, msg, region, section,
 894                         type)) != 0)
 895                         return r;
 896         }
 897         return 0;
 898 }
 899
 900 int
 901 parse_packet(sldns_buffer* pkt, struct msg_parse* msg, struct regional* region)
 902 {
 903         int ret;
 904         if(sldns_buffer_remaining(pkt) < LDNS_HEADER_SIZE)
 905                 return LDNS_RCODE_FORMERR;
 906         /* read the header */
 907         sldns_buffer_read(pkt, &msg->id, sizeof(uint16_t));
 908         msg->flags = sldns_buffer_read_u16(pkt);
 909         msg->qdcount = sldns_buffer_read_u16(pkt);
 910         msg->ancount = sldns_buffer_read_u16(pkt);
 911         msg->nscount = sldns_buffer_read_u16(pkt);
 912         msg->arcount = sldns_buffer_read_u16(pkt);
 913         if(msg->qdcount > 1)
 914                 return LDNS_RCODE_FORMERR;
 915         if((ret = parse_query_section(pkt, msg)) != 0)
 916                 return ret;
 917         if((ret = parse_section(pkt, msg, region, LDNS_SECTION_ANSWER,
 918                 msg->ancount, &msg->an_rrsets)) != 0)
 919                 return ret;
 920         if((ret = parse_section(pkt, msg, region, LDNS_SECTION_AUTHORITY,
 921                 msg->nscount, &msg->ns_rrsets)) != 0)
 922                 return ret;
 923         if(sldns_buffer_remaining(pkt) == 0 && msg->arcount == 1) {
 924                 /* BIND accepts leniently that an EDNS record is missing.
 925                  * so, we do too. */
 926         } else if((ret = parse_section(pkt, msg, region,
 927                 LDNS_SECTION_ADDITIONAL, msg->arcount, &msg->ar_rrsets)) != 0)
 928                 return ret;
 929         /* if(sldns_buffer_remaining(pkt) > 0) { */
 930                 /* there is spurious data at end of packet. ignore */
 931         /* } */
 932         msg->rrset_count = msg->an_rrsets + msg->ns_rrsets + msg->ar_rrsets;
 933         return 0;
 934 }
 935
 936 int
 937 parse_extract_edns(struct msg_parse* msg, struct edns_data* edns)
 938 {
 939         struct rrset_parse* rrset = msg->rrset_first;
 940         struct rrset_parse* prev = 0;
 941         struct rrset_parse* found = 0;
 942         struct rrset_parse* found_prev = 0;
 943         /* since the class encodes the UDP size, we cannot use hash table to
 944          * find the EDNS OPT record. Scan the packet. */
 945         while(rrset) {
 946                 if(rrset->type == LDNS_RR_TYPE_OPT) {
 947                         /* only one OPT RR allowed. */
 948                         if(found) return LDNS_RCODE_FORMERR;
 949                         /* found it! */
 950                         found_prev = prev;
 951                         found = rrset;
 952                 }
 953                 prev = rrset;
 954                 rrset = rrset->rrset_all_next;
 955         }
 956         if(!found) {
 957                 memset(edns, 0, sizeof(*edns));
 958                 edns->udp_size = 512;
 959                 return 0;
 960         }
 961         /* check the found RRset */
 962         /* most lenient check possible. ignore dname, use last opt */
 963         if(found->section != LDNS_SECTION_ADDITIONAL)
 964                 return LDNS_RCODE_FORMERR;
 965         if(found->rr_count == 0)
 966                 return LDNS_RCODE_FORMERR;
 967         if(0) { /* strict checking of dname and RRcount */
 968                 if(found->dname_len != 1 || !found->dname
 969                         || found->dname[0] != 0) return LDNS_RCODE_FORMERR;
 970                 if(found->rr_count != 1) return LDNS_RCODE_FORMERR;
 971         }
 972         log_assert(found->rr_first && found->rr_last);
 973
 974         /* remove from packet */
 975         if(found_prev)  found_prev->rrset_all_next = found->rrset_all_next;
 976         else    msg->rrset_first = found->rrset_all_next;
 977         if(found == msg->rrset_last)
 978                 msg->rrset_last = found_prev;
 979         msg->arcount --;
 980         msg->ar_rrsets --;
 981         msg->rrset_count --;
 982
 983         /* take the data ! */
 984         edns->edns_present = 1;
 985         edns->ext_rcode = found->rr_last->ttl_data[0];
 986         edns->edns_version = found->rr_last->ttl_data[1];
 987         edns->bits = sldns_read_uint16(&found->rr_last->ttl_data[2]);
 988         edns->udp_size = ntohs(found->rrset_class);
 989         /* ignore rdata and rrsigs */
 990         return 0;
 991 }
 992
 993 int
 994 parse_edns_from_pkt(sldns_buffer* pkt, struct edns_data* edns)
 995 {
 996         log_assert(LDNS_QDCOUNT(sldns_buffer_begin(pkt)) == 1);
 997         log_assert(LDNS_ANCOUNT(sldns_buffer_begin(pkt)) == 0);
 998         log_assert(LDNS_NSCOUNT(sldns_buffer_begin(pkt)) == 0);
 999         /* check edns section is present */
1000         if(LDNS_ARCOUNT(sldns_buffer_begin(pkt)) > 1) {
1001                 return LDNS_RCODE_FORMERR;
1002         }
1003         if(LDNS_ARCOUNT(sldns_buffer_begin(pkt)) == 0) {
1004                 memset(edns, 0, sizeof(*edns));
1005                 edns->udp_size = 512;
1006                 return 0;
1007         }
1008         /* domain name must be the root of length 1. */
1009         if(pkt_dname_len(pkt) != 1)
1010                 return LDNS_RCODE_FORMERR;
1011         if(sldns_buffer_remaining(pkt) < 10) /* type, class, ttl, rdatalen */
1012                 return LDNS_RCODE_FORMERR;
1013         if(sldns_buffer_read_u16(pkt) != LDNS_RR_TYPE_OPT)
1014                 return LDNS_RCODE_FORMERR;
1015         edns->edns_present = 1;
1016         edns->udp_size = sldns_buffer_read_u16(pkt); /* class is udp size */
1017         edns->ext_rcode = sldns_buffer_read_u8(pkt); /* ttl used for bits */
1018         edns->edns_version = sldns_buffer_read_u8(pkt);
1019         edns->bits = sldns_buffer_read_u16(pkt);
1020         /* ignore rdata and rrsigs */
1021         return 0;
1022 }