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 74 /** number of buckets in parse rrset hash table. Must be power of 2. */ 75 #define PARSE_TABLE_SIZE 32 76 /** Maximum TTL that is allowed. */ 77 extern time_t MAX_TTL; 78 /** Minimum TTL that is allowed. */ 79 extern time_t MIN_TTL; 80 /** Maximum Negative TTL that is allowed */ 81 extern time_t MAX_NEG_TTL; 82 /** If we serve expired entries and prefetch them */ 83 extern int SERVE_EXPIRED; 84 /** Time to serve records after expiration */ 85 extern time_t SERVE_EXPIRED_TTL; 86 /** TTL to use for expired records */ 87 extern time_t SERVE_EXPIRED_REPLY_TTL; 88 /** Negative cache time (for entries without any RRs.) */ 89 #define NORR_TTL 5 /* seconds */ 90 /** If we serve the original TTL or decrementing TTLs */ 91 extern int SERVE_ORIGINAL_TTL; 92 93 /** 94 * Data stored in scratch pad memory during parsing. 95 * Stores the data that will enter into the msgreply and packet result. 96 */ 97 struct msg_parse { 98 /** id from message, network format. */ 99 uint16_t id; 100 /** flags from message, host format. */ 101 uint16_t flags; 102 /** count of RRs, host format */ 103 uint16_t qdcount; 104 /** count of RRs, host format */ 105 uint16_t ancount; 106 /** count of RRs, host format */ 107 uint16_t nscount; 108 /** count of RRs, host format */ 109 uint16_t arcount; 110 /** count of RRsets per section. */ 111 size_t an_rrsets; 112 /** count of RRsets per section. */ 113 size_t ns_rrsets; 114 /** count of RRsets per section. */ 115 size_t ar_rrsets; 116 /** total number of rrsets found. */ 117 size_t rrset_count; 118 119 /** query dname (pointer to start location in packet, NULL if none */ 120 uint8_t* qname; 121 /** length of query dname in octets, 0 if none */ 122 size_t qname_len; 123 /** query type, host order. 0 if qdcount=0 */ 124 uint16_t qtype; 125 /** query class, host order. 0 if qdcount=0 */ 126 uint16_t qclass; 127 128 /** 129 * Hash table array used during parsing to lookup rrset types. 130 * Based on name, type, class. Same hash value as in rrset cache. 131 */ 132 struct rrset_parse* hashtable[PARSE_TABLE_SIZE]; 133 134 /** linked list of rrsets that have been found (in order). */ 135 struct rrset_parse* rrset_first; 136 /** last element of rrset list. */ 137 struct rrset_parse* rrset_last; 138 }; 139 140 /** 141 * Data stored for an rrset during parsing. 142 */ 143 struct rrset_parse { 144 /** next in hash bucket */ 145 struct rrset_parse* rrset_bucket_next; 146 /** next in list of all rrsets */ 147 struct rrset_parse* rrset_all_next; 148 /** hash value of rrset */ 149 hashvalue_type hash; 150 /** which section was it found in: one of 151 * LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL 152 */ 153 sldns_pkt_section section; 154 /** start of (possibly compressed) dname in packet */ 155 uint8_t* dname; 156 /** length of the dname uncompressed wireformat */ 157 size_t dname_len; 158 /** type, host order. */ 159 uint16_t type; 160 /** class, network order. var name so that it is not a c++ keyword. */ 161 uint16_t rrset_class; 162 /** the flags for the rrset, like for packedrrset */ 163 uint32_t flags; 164 /** number of RRs in the rr list */ 165 size_t rr_count; 166 /** sum of RR rdata sizes */ 167 size_t size; 168 /** linked list of RRs in this rrset. */ 169 struct rr_parse* rr_first; 170 /** last in list of RRs in this rrset. */ 171 struct rr_parse* rr_last; 172 /** number of RRSIGs over this rrset. */ 173 size_t rrsig_count; 174 /** linked list of RRsig RRs over this rrset. */ 175 struct rr_parse* rrsig_first; 176 /** last in list of RRSIG RRs over this rrset. */ 177 struct rr_parse* rrsig_last; 178 }; 179 180 /** 181 * Data stored for an RR during parsing. 182 */ 183 struct rr_parse { 184 /** 185 * Pointer to the RR. Points to start of TTL value in the packet. 186 * Rdata length and rdata follow it. 187 * its dname, type and class are the same and stored for the rrset. 188 */ 189 uint8_t* ttl_data; 190 /** true if ttl_data is not part of the packet, but elsewhere in mem. 191 * Set for generated CNAMEs for DNAMEs. */ 192 int outside_packet; 193 /** the length of the rdata if allocated (with no dname compression)*/ 194 size_t size; 195 /** next in list of RRs. */ 196 struct rr_parse* next; 197 }; 198 199 /** Check if label length is first octet of a compression pointer, pass u8. */ 200 #define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 ) 201 /** Calculate destination offset of a compression pointer. pass first and 202 * second octets of the compression pointer. */ 203 #define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) ) 204 /** create a compression pointer to the given offset. */ 205 #define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset))) 206 207 /** error codes, extended with EDNS, so > 15. */ 208 #define EDNS_RCODE_BADVERS 16 /** bad EDNS version */ 209 /** largest valid compression offset */ 210 #define PTR_MAX_OFFSET 0x3fff 211 212 /** 213 * EDNS data storage 214 * rdata is parsed in a list (has accessor functions). allocated in a 215 * region. 216 */ 217 struct edns_data { 218 /** if EDNS OPT record was present */ 219 int edns_present; 220 /** Extended RCODE */ 221 uint8_t ext_rcode; 222 /** The EDNS version number */ 223 uint8_t edns_version; 224 /** the EDNS bits field from ttl (host order): Z */ 225 uint16_t bits; 226 /** UDP reassembly size. */ 227 uint16_t udp_size; 228 /** rdata element list, or NULL if none */ 229 struct edns_option* opt_list; 230 /** block size to pad */ 231 uint16_t padding_block_size; 232 }; 233 234 /** 235 * EDNS option 236 */ 237 struct edns_option { 238 /** next item in list */ 239 struct edns_option* next; 240 /** type of this edns option */ 241 uint16_t opt_code; 242 /** length of this edns option (cannot exceed uint16 in encoding) */ 243 size_t opt_len; 244 /** data of this edns option; allocated in region, or NULL if len=0 */ 245 uint8_t* opt_data; 246 }; 247 248 /** 249 * Obtain size in the packet of an rr type, that is before dname type. 250 * Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types. 251 * @param rdf: the rdf type from the descriptor. 252 * @return: size in octets. 0 on failure. 253 */ 254 size_t get_rdf_size(sldns_rdf_type rdf); 255 256 /** 257 * Parse the packet. 258 * @param pkt: packet, position at call must be at start of packet. 259 * at end position is after packet. 260 * @param msg: where to store results. 261 * @param region: how to alloc results. 262 * @return: 0 if OK, or rcode on error. 263 */ 264 int parse_packet(struct sldns_buffer* pkt, struct msg_parse* msg, 265 struct regional* region); 266 267 /** 268 * After parsing the packet, extract EDNS data from packet. 269 * If not present this is noted in the data structure. 270 * If a parse error happens, an error code is returned. 271 * 272 * Quirks: 273 * o ignores OPT rdata. 274 * o ignores OPT owner name. 275 * o ignores extra OPT records, except the last one in the packet. 276 * 277 * @param msg: parsed message structure. Modified on exit, if EDNS was present 278 * it is removed from the additional section. 279 * @param edns: the edns data is stored here. Does not have to be initialised. 280 * @param region: region to alloc results in (edns option contents) 281 * @return: 0 on success. or an RCODE on an error. 282 * RCODE formerr if OPT in wrong section, and so on. 283 */ 284 int parse_extract_edns(struct msg_parse* msg, struct edns_data* edns, 285 struct regional* region); 286 287 /** 288 * If EDNS data follows a query section, extract it and initialize edns struct. 289 * @param pkt: the packet. position at start must be right after the query 290 * section. At end, right after EDNS data or no movement if failed. 291 * @param edns: the edns data allocated by the caller. Does not have to be 292 * initialised. 293 * @param region: region to alloc results in (edns option contents) 294 * @return: 0 on success, or an RCODE on error. 295 * RCODE formerr if OPT is badly formatted and so on. 296 */ 297 int parse_edns_from_pkt(struct sldns_buffer* pkt, struct edns_data* edns, 298 struct regional* region); 299 300 /** 301 * Calculate hash value for rrset in packet. 302 * @param pkt: the packet. 303 * @param dname: pointer to uncompressed dname, or compressed dname in packet. 304 * @param type: rrset type in host order. 305 * @param dclass: rrset class in network order. 306 * @param rrset_flags: rrset flags (same as packed_rrset flags). 307 * @return hash value 308 */ 309 hashvalue_type pkt_hash_rrset(struct sldns_buffer* pkt, uint8_t* dname, 310 uint16_t type, uint16_t dclass, uint32_t rrset_flags); 311 312 /** 313 * Lookup in msg hashtable to find a rrset. 314 * @param msg: with the hashtable. 315 * @param pkt: packet for compressed names. 316 * @param h: hash value 317 * @param rrset_flags: flags of rrset sought for. 318 * @param dname: name of rrset sought for. 319 * @param dnamelen: len of dname. 320 * @param type: rrset type, host order. 321 * @param dclass: rrset class, network order. 322 * @return NULL or the rrset_parse if found. 323 */ 324 struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg, 325 struct sldns_buffer* pkt, hashvalue_type h, uint32_t rrset_flags, 326 uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass); 327 328 /** 329 * Remove rrset from hash table. 330 * @param msg: with hashtable. 331 * @param rrset: with hash value and id info. 332 */ 333 void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset); 334 335 /** 336 * Log the edns options in the edns option list. 337 * @param level: the verbosity level. 338 * @param info_str: the informational string to be printed before the options. 339 * @param list: the edns option list. 340 */ 341 void log_edns_opt_list(enum verbosity_value level, const char* info_str, 342 struct edns_option* list); 343 344 #endif /* UTIL_DATA_MSGPARSE_H */ 345