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