1 /* 2 * util/data/msgparse.h - 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 * Contains message parsing data structures. 38 * These point back into the packet buffer. 39 * 40 * During parsing RRSIGS are put together with the rrsets they (claim to) sign. 41 * This process works as follows: 42 * o if RRSIG follows the data rrset, it is added to the rrset rrsig list. 43 * o if no matching data rrset is found, the RRSIG becomes a new rrset. 44 * o If the data rrset later follows the RRSIG 45 * o See if the RRSIG rrset contains multiple types, and needs to 46 * have the rrsig(s) for that data type split off. 47 * o Put the data rr as data type in the rrset and rrsig in list. 48 * o RRSIGs are allowed to move to a different section. The section of 49 * the data item is used for the final rrset. 50 * o multiple signatures over an RRset are possible. 51 * 52 * For queries of qtype=RRSIG, some special handling is needed, to avoid 53 * splitting the RRSIG in the answer section. 54 * o duplicate, not split, RRSIGs from the answer section, if qtype=RRSIG. 55 * o check for doubles in the rrsig list when adding an RRSIG to data, 56 * so that a data rrset is signed by RRSIGs with different rdata. 57 * when qtype=RRSIG. 58 * This will move the RRSIG from the answer section to sign the data further 59 * in the packet (if possible). If then after that, more RRSIGs are found 60 * that sign the data as well, doubles are removed. 61 */ 62 63 #ifndef UTIL_DATA_MSGPARSE_H 64 #define UTIL_DATA_MSGPARSE_H 65 #include "util/storage/lruhash.h" 66 #include "sldns/pkthdr.h" 67 #include "sldns/rrdef.h" 68 struct sldns_buffer; 69 struct rrset_parse; 70 struct rr_parse; 71 struct regional; 72 struct edns_option; 73 struct config_file; 74 struct comm_point; 75 struct comm_reply; 76 struct cookie_secrets; 77 78 /** number of buckets in parse rrset hash table. Must be power of 2. */ 79 #define PARSE_TABLE_SIZE 32 80 /** Maximum TTL that is allowed. */ 81 extern time_t MAX_TTL; 82 /** Minimum TTL that is allowed. */ 83 extern time_t MIN_TTL; 84 /** Maximum Negative TTL that is allowed */ 85 extern time_t MAX_NEG_TTL; 86 /** Minimum Negative TTL that is allowed */ 87 extern time_t MIN_NEG_TTL; 88 /** If we serve expired entries and prefetch them */ 89 extern int SERVE_EXPIRED; 90 /** Time to serve records after expiration */ 91 extern time_t SERVE_EXPIRED_TTL; 92 /** Reset serve expired TTL after failed update attempt */ 93 extern time_t SERVE_EXPIRED_TTL_RESET; 94 /** TTL to use for expired records */ 95 extern time_t SERVE_EXPIRED_REPLY_TTL; 96 /** Negative cache time (for entries without any RRs.) */ 97 #define NORR_TTL 5 /* seconds */ 98 /** If we serve the original TTL or decrementing TTLs */ 99 extern int SERVE_ORIGINAL_TTL; 100 101 /** 102 * Data stored in scratch pad memory during parsing. 103 * Stores the data that will enter into the msgreply and packet result. 104 */ 105 struct msg_parse { 106 /** id from message, network format. */ 107 uint16_t id; 108 /** flags from message, host format. */ 109 uint16_t flags; 110 /** count of RRs, host format */ 111 uint16_t qdcount; 112 /** count of RRs, host format */ 113 uint16_t ancount; 114 /** count of RRs, host format */ 115 uint16_t nscount; 116 /** count of RRs, host format */ 117 uint16_t arcount; 118 /** count of RRsets per section. */ 119 size_t an_rrsets; 120 /** count of RRsets per section. */ 121 size_t ns_rrsets; 122 /** count of RRsets per section. */ 123 size_t ar_rrsets; 124 /** total number of rrsets found. */ 125 size_t rrset_count; 126 127 /** query dname (pointer to start location in packet, NULL if none */ 128 uint8_t* qname; 129 /** length of query dname in octets, 0 if none */ 130 size_t qname_len; 131 /** query type, host order. 0 if qdcount=0 */ 132 uint16_t qtype; 133 /** query class, host order. 0 if qdcount=0 */ 134 uint16_t qclass; 135 136 /** 137 * Hash table array used during parsing to lookup rrset types. 138 * Based on name, type, class. Same hash value as in rrset cache. 139 */ 140 struct rrset_parse* hashtable[PARSE_TABLE_SIZE]; 141 142 /** linked list of rrsets that have been found (in order). */ 143 struct rrset_parse* rrset_first; 144 /** last element of rrset list. */ 145 struct rrset_parse* rrset_last; 146 }; 147 148 /** 149 * Data stored for an rrset during parsing. 150 */ 151 struct rrset_parse { 152 /** next in hash bucket */ 153 struct rrset_parse* rrset_bucket_next; 154 /** next in list of all rrsets */ 155 struct rrset_parse* rrset_all_next; 156 /** hash value of rrset */ 157 hashvalue_type hash; 158 /** which section was it found in: one of 159 * LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL 160 */ 161 sldns_pkt_section section; 162 /** start of (possibly compressed) dname in packet */ 163 uint8_t* dname; 164 /** length of the dname uncompressed wireformat */ 165 size_t dname_len; 166 /** type, host order. */ 167 uint16_t type; 168 /** class, network order. var name so that it is not a c++ keyword. */ 169 uint16_t rrset_class; 170 /** the flags for the rrset, like for packedrrset */ 171 uint32_t flags; 172 /** number of RRs in the rr list */ 173 size_t rr_count; 174 /** sum of RR rdata sizes */ 175 size_t size; 176 /** linked list of RRs in this rrset. */ 177 struct rr_parse* rr_first; 178 /** last in list of RRs in this rrset. */ 179 struct rr_parse* rr_last; 180 /** number of RRSIGs over this rrset. */ 181 size_t rrsig_count; 182 /** linked list of RRsig RRs over this rrset. */ 183 struct rr_parse* rrsig_first; 184 /** last in list of RRSIG RRs over this rrset. */ 185 struct rr_parse* rrsig_last; 186 }; 187 188 /** 189 * Data stored for an RR during parsing. 190 */ 191 struct rr_parse { 192 /** 193 * Pointer to the RR. Points to start of TTL value in the packet. 194 * Rdata length and rdata follow it. 195 * its dname, type and class are the same and stored for the rrset. 196 */ 197 uint8_t* ttl_data; 198 /** true if ttl_data is not part of the packet, but elsewhere in mem. 199 * Set for generated CNAMEs for DNAMEs. */ 200 int outside_packet; 201 /** the length of the rdata if allocated (with no dname compression)*/ 202 size_t size; 203 /** next in list of RRs. */ 204 struct rr_parse* next; 205 }; 206 207 /** Check if label length is first octet of a compression pointer, pass u8. */ 208 #define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 ) 209 /** Calculate destination offset of a compression pointer. pass first and 210 * second octets of the compression pointer. */ 211 #define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) ) 212 /** create a compression pointer to the given offset. */ 213 #define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset))) 214 215 /** error codes, extended with EDNS, so > 15. */ 216 #define EDNS_RCODE_BADVERS 16 /** bad EDNS version */ 217 /** largest valid compression offset */ 218 #define PTR_MAX_OFFSET 0x3fff 219 220 /** 221 * EDNS data storage 222 * rdata is parsed in a list (has accessor functions). allocated in a 223 * region. 224 */ 225 struct edns_data { 226 /** Extended RCODE */ 227 uint8_t ext_rcode; 228 /** The EDNS version number */ 229 uint8_t edns_version; 230 /** the EDNS bits field from ttl (host order): Z */ 231 uint16_t bits; 232 /** UDP reassembly size. */ 233 uint16_t udp_size; 234 /** rdata element list of options of an incoming packet created at 235 * parse time, or NULL if none */ 236 struct edns_option* opt_list_in; 237 /** rdata element list of options to encode for outgoing packets, 238 * or NULL if none */ 239 struct edns_option* opt_list_out; 240 /** rdata element list of outgoing edns options from modules 241 * or NULL if none */ 242 struct edns_option* opt_list_inplace_cb_out; 243 /** block size to pad */ 244 uint16_t padding_block_size; 245 /** if EDNS OPT record was present */ 246 unsigned int edns_present : 1; 247 /** if a cookie was present */ 248 unsigned int cookie_present : 1; 249 /** if the cookie validated */ 250 unsigned int cookie_valid : 1; 251 /** if the cookie holds only the client part */ 252 unsigned int cookie_client : 1; 253 }; 254 255 /** 256 * EDNS option 257 */ 258 struct edns_option { 259 /** next item in list */ 260 struct edns_option* next; 261 /** type of this edns option */ 262 uint16_t opt_code; 263 /** length of this edns option (cannot exceed uint16 in encoding) */ 264 size_t opt_len; 265 /** data of this edns option; allocated in region, or NULL if len=0 */ 266 uint8_t* opt_data; 267 }; 268 269 /** 270 * Obtain size in the packet of an rr type, that is before dname type. 271 * Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types. 272 * @param rdf: the rdf type from the descriptor. 273 * @return: size in octets. 0 on failure. 274 */ 275 size_t get_rdf_size(sldns_rdf_type rdf); 276 277 /** 278 * Parse the packet. 279 * @param pkt: packet, position at call must be at start of packet. 280 * at end position is after packet. 281 * @param msg: where to store results. 282 * @param region: how to alloc results. 283 * @return: 0 if OK, or rcode on error. 284 */ 285 int parse_packet(struct sldns_buffer* pkt, struct msg_parse* msg, 286 struct regional* region); 287 288 /** 289 * After parsing the packet, extract EDNS data from packet. 290 * If not present this is noted in the data structure. 291 * If a parse error happens, an error code is returned. 292 * 293 * Quirks: 294 * o ignores OPT rdata. 295 * o ignores OPT owner name. 296 * o ignores extra OPT records, except the last one in the packet. 297 * 298 * @param msg: parsed message structure. Modified on exit, if EDNS was present 299 * it is removed from the additional section. 300 * @param edns: the edns data is stored here. Does not have to be initialised. 301 * @param region: region to alloc results in (edns option contents) 302 * @return: 0 on success. or an RCODE on an error. 303 * RCODE formerr if OPT in wrong section, and so on. 304 */ 305 int parse_extract_edns_from_response_msg(struct msg_parse* msg, 306 struct edns_data* edns, struct regional* region); 307 308 /** 309 * Skip RRs from packet 310 * @param pkt: the packet. position at start must be right after the query 311 * section. At end, right after EDNS data or no movement if failed. 312 * @param num: Limit of the number of records we want to parse. 313 * @return: 0 on success, 1 on failure. 314 */ 315 int skip_pkt_rrs(struct sldns_buffer* pkt, int num); 316 317 /** 318 * If EDNS data follows a query section, extract it and initialize edns struct. 319 * @param pkt: the packet. position at start must be right after the query 320 * section. At end, right after EDNS data or no movement if failed. 321 * @param edns: the edns data allocated by the caller. Does not have to be 322 * initialised. 323 * @param cfg: the configuration (with nsid value etc.) 324 * @param c: commpoint to determine transport (if needed) 325 * @param repinfo: commreply to determine the client address 326 * @param now: current time 327 * @param region: region to alloc results in (edns option contents) 328 * @param cookie_secrets: the cookie secrets for EDNS COOKIE validation. 329 * @return: 0 on success, or an RCODE on error. 330 * RCODE formerr if OPT is badly formatted and so on. 331 */ 332 int parse_edns_from_query_pkt(struct sldns_buffer* pkt, struct edns_data* edns, 333 struct config_file* cfg, struct comm_point* c, 334 struct comm_reply* repinfo, time_t now, struct regional* region, 335 struct cookie_secrets* cookie_secrets); 336 337 /** 338 * Calculate hash value for rrset in packet. 339 * @param pkt: the packet. 340 * @param dname: pointer to uncompressed dname, or compressed dname in packet. 341 * @param type: rrset type in host order. 342 * @param dclass: rrset class in network order. 343 * @param rrset_flags: rrset flags (same as packed_rrset flags). 344 * @return hash value 345 */ 346 hashvalue_type pkt_hash_rrset(struct sldns_buffer* pkt, uint8_t* dname, 347 uint16_t type, uint16_t dclass, uint32_t rrset_flags); 348 349 /** 350 * Lookup in msg hashtable to find a rrset. 351 * @param msg: with the hashtable. 352 * @param pkt: packet for compressed names. 353 * @param h: hash value 354 * @param rrset_flags: flags of rrset sought for. 355 * @param dname: name of rrset sought for. 356 * @param dnamelen: len of dname. 357 * @param type: rrset type, host order. 358 * @param dclass: rrset class, network order. 359 * @return NULL or the rrset_parse if found. 360 */ 361 struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg, 362 struct sldns_buffer* pkt, hashvalue_type h, uint32_t rrset_flags, 363 uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass); 364 365 /** 366 * Remove rrset from hash table. 367 * @param msg: with hashtable. 368 * @param rrset: with hash value and id info. 369 */ 370 void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset); 371 372 /** 373 * Log the edns options in the edns option list. 374 * @param level: the verbosity level. 375 * @param info_str: the informational string to be printed before the options. 376 * @param list: the edns option list. 377 */ 378 void log_edns_opt_list(enum verbosity_value level, const char* info_str, 379 struct edns_option* list); 380 381 /** 382 * Remove RR from msgparse RRset. 383 * @param str: this string is used for logging if verbose. If NULL, there is 384 * no logging of the remove. 385 * @param pkt: packet in buffer that is removed from. Used to log the name 386 * of the item removed. 387 * @param rrset: RRset that the RR is removed from. 388 * @param prev: previous RR in list, or NULL. 389 * @param rr: RR that is removed. 390 * @param addr: address used for logging, if verbose, or NULL then it is not 391 * used. 392 * @param addrlen: length of addr, if that is not NULL. 393 * @return true if rrset is entirely bad, it would then need to be removed. 394 */ 395 int msgparse_rrset_remove_rr(const char* str, struct sldns_buffer* pkt, 396 struct rrset_parse* rrset, struct rr_parse* prev, struct rr_parse* rr, 397 struct sockaddr_storage* addr, socklen_t addrlen); 398 399 #endif /* UTIL_DATA_MSGPARSE_H */ 400