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