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