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 "ldns/pkthdr.h" 67 #include "ldns/rrdef.h" 68 struct sldns_buffer; 69 struct rrset_parse; 70 struct rr_parse; 71 struct regional; 72 73 /** number of buckets in parse rrset hash table. Must be power of 2. */ 74 #define PARSE_TABLE_SIZE 32 75 /** Maximum TTL that is allowed. */ 76 extern time_t MAX_TTL; 77 /** Minimum TTL that is allowed. */ 78 extern time_t MIN_TTL; 79 /** Negative cache time (for entries without any RRs.) */ 80 #define NORR_TTL 5 /* seconds */ 81 82 /** 83 * Data stored in scratch pad memory during parsing. 84 * Stores the data that will enter into the msgreply and packet result. 85 */ 86 struct msg_parse { 87 /** id from message, network format. */ 88 uint16_t id; 89 /** flags from message, host format. */ 90 uint16_t flags; 91 /** count of RRs, host format */ 92 uint16_t qdcount; 93 /** count of RRs, host format */ 94 uint16_t ancount; 95 /** count of RRs, host format */ 96 uint16_t nscount; 97 /** count of RRs, host format */ 98 uint16_t arcount; 99 /** count of RRsets per section. */ 100 size_t an_rrsets; 101 /** count of RRsets per section. */ 102 size_t ns_rrsets; 103 /** count of RRsets per section. */ 104 size_t ar_rrsets; 105 /** total number of rrsets found. */ 106 size_t rrset_count; 107 108 /** query dname (pointer to start location in packet, NULL if none */ 109 uint8_t* qname; 110 /** length of query dname in octets, 0 if none */ 111 size_t qname_len; 112 /** query type, host order. 0 if qdcount=0 */ 113 uint16_t qtype; 114 /** query class, host order. 0 if qdcount=0 */ 115 uint16_t qclass; 116 117 /** 118 * Hash table array used during parsing to lookup rrset types. 119 * Based on name, type, class. Same hash value as in rrset cache. 120 */ 121 struct rrset_parse* hashtable[PARSE_TABLE_SIZE]; 122 123 /** linked list of rrsets that have been found (in order). */ 124 struct rrset_parse* rrset_first; 125 /** last element of rrset list. */ 126 struct rrset_parse* rrset_last; 127 }; 128 129 /** 130 * Data stored for an rrset during parsing. 131 */ 132 struct rrset_parse { 133 /** next in hash bucket */ 134 struct rrset_parse* rrset_bucket_next; 135 /** next in list of all rrsets */ 136 struct rrset_parse* rrset_all_next; 137 /** hash value of rrset */ 138 hashvalue_t hash; 139 /** which section was it found in: one of 140 * LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL 141 */ 142 sldns_pkt_section section; 143 /** start of (possibly compressed) dname in packet */ 144 uint8_t* dname; 145 /** length of the dname uncompressed wireformat */ 146 size_t dname_len; 147 /** type, host order. */ 148 uint16_t type; 149 /** class, network order. var name so that it is not a c++ keyword. */ 150 uint16_t rrset_class; 151 /** the flags for the rrset, like for packedrrset */ 152 uint32_t flags; 153 /** number of RRs in the rr list */ 154 size_t rr_count; 155 /** sum of RR rdata sizes */ 156 size_t size; 157 /** linked list of RRs in this rrset. */ 158 struct rr_parse* rr_first; 159 /** last in list of RRs in this rrset. */ 160 struct rr_parse* rr_last; 161 /** number of RRSIGs over this rrset. */ 162 size_t rrsig_count; 163 /** linked list of RRsig RRs over this rrset. */ 164 struct rr_parse* rrsig_first; 165 /** last in list of RRSIG RRs over this rrset. */ 166 struct rr_parse* rrsig_last; 167 }; 168 169 /** 170 * Data stored for an RR during parsing. 171 */ 172 struct rr_parse { 173 /** 174 * Pointer to the RR. Points to start of TTL value in the packet. 175 * Rdata length and rdata follow it. 176 * its dname, type and class are the same and stored for the rrset. 177 */ 178 uint8_t* ttl_data; 179 /** true if ttl_data is not part of the packet, but elsewhere in mem. 180 * Set for generated CNAMEs for DNAMEs. */ 181 int outside_packet; 182 /** the length of the rdata if allocated (with no dname compression)*/ 183 size_t size; 184 /** next in list of RRs. */ 185 struct rr_parse* next; 186 }; 187 188 /** Check if label length is first octet of a compression pointer, pass u8. */ 189 #define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 ) 190 /** Calculate destination offset of a compression pointer. pass first and 191 * second octets of the compression pointer. */ 192 #define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) ) 193 /** create a compression pointer to the given offset. */ 194 #define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset))) 195 196 /** error codes, extended with EDNS, so > 15. */ 197 #define EDNS_RCODE_BADVERS 16 /** bad EDNS version */ 198 /** largest valid compression offset */ 199 #define PTR_MAX_OFFSET 0x3fff 200 201 /** 202 * EDNS data storage 203 * EDNS rdata is ignored. 204 */ 205 struct edns_data { 206 /** if EDNS OPT record was present */ 207 int edns_present; 208 /** Extended RCODE */ 209 uint8_t ext_rcode; 210 /** The EDNS version number */ 211 uint8_t edns_version; 212 /** the EDNS bits field from ttl (host order): Z */ 213 uint16_t bits; 214 /** UDP reassembly size. */ 215 uint16_t udp_size; 216 }; 217 218 /** 219 * Obtain size in the packet of an rr type, that is before dname type. 220 * Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types. 221 * @param rdf: the rdf type from the descriptor. 222 * @return: size in octets. 0 on failure. 223 */ 224 size_t get_rdf_size(sldns_rdf_type rdf); 225 226 /** 227 * Parse the packet. 228 * @param pkt: packet, position at call must be at start of packet. 229 * at end position is after packet. 230 * @param msg: where to store results. 231 * @param region: how to alloc results. 232 * @return: 0 if OK, or rcode on error. 233 */ 234 int parse_packet(struct sldns_buffer* pkt, struct msg_parse* msg, 235 struct regional* region); 236 237 /** 238 * After parsing the packet, extract EDNS data from packet. 239 * If not present this is noted in the data structure. 240 * If a parse error happens, an error code is returned. 241 * 242 * Quirks: 243 * o ignores OPT rdata. 244 * o ignores OPT owner name. 245 * o ignores extra OPT records, except the last one in the packet. 246 * 247 * @param msg: parsed message structure. Modified on exit, if EDNS was present 248 * it is removed from the additional section. 249 * @param edns: the edns data is stored here. Does not have to be initialised. 250 * @return: 0 on success. or an RCODE on an error. 251 * RCODE formerr if OPT in wrong section, and so on. 252 */ 253 int parse_extract_edns(struct msg_parse* msg, struct edns_data* edns); 254 255 /** 256 * If EDNS data follows a query section, extract it and initialize edns struct. 257 * @param pkt: the packet. position at start must be right after the query 258 * section. At end, right after EDNS data or no movement if failed. 259 * @param edns: the edns data allocated by the caller. Does not have to be 260 * initialised. 261 * @return: 0 on success, or an RCODE on error. 262 * RCODE formerr if OPT is badly formatted and so on. 263 */ 264 int parse_edns_from_pkt(struct sldns_buffer* pkt, struct edns_data* edns); 265 266 /** 267 * Calculate hash value for rrset in packet. 268 * @param pkt: the packet. 269 * @param dname: pointer to uncompressed dname, or compressed dname in packet. 270 * @param type: rrset type in host order. 271 * @param dclass: rrset class in network order. 272 * @param rrset_flags: rrset flags (same as packed_rrset flags). 273 * @return hash value 274 */ 275 hashvalue_t pkt_hash_rrset(struct sldns_buffer* pkt, uint8_t* dname, uint16_t type, 276 uint16_t dclass, uint32_t rrset_flags); 277 278 /** 279 * Lookup in msg hashtable to find a rrset. 280 * @param msg: with the hashtable. 281 * @param pkt: packet for compressed names. 282 * @param h: hash value 283 * @param rrset_flags: flags of rrset sought for. 284 * @param dname: name of rrset sought for. 285 * @param dnamelen: len of dname. 286 * @param type: rrset type, host order. 287 * @param dclass: rrset class, network order. 288 * @return NULL or the rrset_parse if found. 289 */ 290 struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg, 291 struct sldns_buffer* pkt, hashvalue_t h, uint32_t rrset_flags, 292 uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass); 293 294 /** 295 * Remove rrset from hash table. 296 * @param msg: with hashtable. 297 * @param rrset: with hash value and id info. 298 */ 299 void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset); 300 301 #endif /* UTIL_DATA_MSGPARSE_H */ 302