msgparse.h revision 302408
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" 68struct sldns_buffer; 69struct rrset_parse; 70struct rr_parse; 71struct 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. */ 76extern time_t MAX_TTL; 77/** Minimum TTL that is allowed. */ 78extern time_t MIN_TTL; 79/** Maximum Negative TTL that is allowed */ 80extern time_t MAX_NEG_TTL; 81/** Negative cache time (for entries without any RRs.) */ 82#define NORR_TTL 5 /* seconds */ 83 84/** 85 * Data stored in scratch pad memory during parsing. 86 * Stores the data that will enter into the msgreply and packet result. 87 */ 88struct msg_parse { 89 /** id from message, network format. */ 90 uint16_t id; 91 /** flags from message, host format. */ 92 uint16_t flags; 93 /** count of RRs, host format */ 94 uint16_t qdcount; 95 /** count of RRs, host format */ 96 uint16_t ancount; 97 /** count of RRs, host format */ 98 uint16_t nscount; 99 /** count of RRs, host format */ 100 uint16_t arcount; 101 /** count of RRsets per section. */ 102 size_t an_rrsets; 103 /** count of RRsets per section. */ 104 size_t ns_rrsets; 105 /** count of RRsets per section. */ 106 size_t ar_rrsets; 107 /** total number of rrsets found. */ 108 size_t rrset_count; 109 110 /** query dname (pointer to start location in packet, NULL if none */ 111 uint8_t* qname; 112 /** length of query dname in octets, 0 if none */ 113 size_t qname_len; 114 /** query type, host order. 0 if qdcount=0 */ 115 uint16_t qtype; 116 /** query class, host order. 0 if qdcount=0 */ 117 uint16_t qclass; 118 119 /** 120 * Hash table array used during parsing to lookup rrset types. 121 * Based on name, type, class. Same hash value as in rrset cache. 122 */ 123 struct rrset_parse* hashtable[PARSE_TABLE_SIZE]; 124 125 /** linked list of rrsets that have been found (in order). */ 126 struct rrset_parse* rrset_first; 127 /** last element of rrset list. */ 128 struct rrset_parse* rrset_last; 129}; 130 131/** 132 * Data stored for an rrset during parsing. 133 */ 134struct rrset_parse { 135 /** next in hash bucket */ 136 struct rrset_parse* rrset_bucket_next; 137 /** next in list of all rrsets */ 138 struct rrset_parse* rrset_all_next; 139 /** hash value of rrset */ 140 hashvalue_t hash; 141 /** which section was it found in: one of 142 * LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL 143 */ 144 sldns_pkt_section section; 145 /** start of (possibly compressed) dname in packet */ 146 uint8_t* dname; 147 /** length of the dname uncompressed wireformat */ 148 size_t dname_len; 149 /** type, host order. */ 150 uint16_t type; 151 /** class, network order. var name so that it is not a c++ keyword. */ 152 uint16_t rrset_class; 153 /** the flags for the rrset, like for packedrrset */ 154 uint32_t flags; 155 /** number of RRs in the rr list */ 156 size_t rr_count; 157 /** sum of RR rdata sizes */ 158 size_t size; 159 /** linked list of RRs in this rrset. */ 160 struct rr_parse* rr_first; 161 /** last in list of RRs in this rrset. */ 162 struct rr_parse* rr_last; 163 /** number of RRSIGs over this rrset. */ 164 size_t rrsig_count; 165 /** linked list of RRsig RRs over this rrset. */ 166 struct rr_parse* rrsig_first; 167 /** last in list of RRSIG RRs over this rrset. */ 168 struct rr_parse* rrsig_last; 169}; 170 171/** 172 * Data stored for an RR during parsing. 173 */ 174struct rr_parse { 175 /** 176 * Pointer to the RR. Points to start of TTL value in the packet. 177 * Rdata length and rdata follow it. 178 * its dname, type and class are the same and stored for the rrset. 179 */ 180 uint8_t* ttl_data; 181 /** true if ttl_data is not part of the packet, but elsewhere in mem. 182 * Set for generated CNAMEs for DNAMEs. */ 183 int outside_packet; 184 /** the length of the rdata if allocated (with no dname compression)*/ 185 size_t size; 186 /** next in list of RRs. */ 187 struct rr_parse* next; 188}; 189 190/** Check if label length is first octet of a compression pointer, pass u8. */ 191#define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 ) 192/** Calculate destination offset of a compression pointer. pass first and 193 * second octets of the compression pointer. */ 194#define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) ) 195/** create a compression pointer to the given offset. */ 196#define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset))) 197 198/** error codes, extended with EDNS, so > 15. */ 199#define EDNS_RCODE_BADVERS 16 /** bad EDNS version */ 200/** largest valid compression offset */ 201#define PTR_MAX_OFFSET 0x3fff 202 203/** 204 * EDNS data storage 205 * EDNS rdata is ignored. 206 */ 207struct edns_data { 208 /** if EDNS OPT record was present */ 209 int edns_present; 210 /** Extended RCODE */ 211 uint8_t ext_rcode; 212 /** The EDNS version number */ 213 uint8_t edns_version; 214 /** the EDNS bits field from ttl (host order): Z */ 215 uint16_t bits; 216 /** UDP reassembly size. */ 217 uint16_t udp_size; 218}; 219 220/** 221 * Obtain size in the packet of an rr type, that is before dname type. 222 * Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types. 223 * @param rdf: the rdf type from the descriptor. 224 * @return: size in octets. 0 on failure. 225 */ 226size_t get_rdf_size(sldns_rdf_type rdf); 227 228/** 229 * Parse the packet. 230 * @param pkt: packet, position at call must be at start of packet. 231 * at end position is after packet. 232 * @param msg: where to store results. 233 * @param region: how to alloc results. 234 * @return: 0 if OK, or rcode on error. 235 */ 236int parse_packet(struct sldns_buffer* pkt, struct msg_parse* msg, 237 struct regional* region); 238 239/** 240 * After parsing the packet, extract EDNS data from packet. 241 * If not present this is noted in the data structure. 242 * If a parse error happens, an error code is returned. 243 * 244 * Quirks: 245 * o ignores OPT rdata. 246 * o ignores OPT owner name. 247 * o ignores extra OPT records, except the last one in the packet. 248 * 249 * @param msg: parsed message structure. Modified on exit, if EDNS was present 250 * it is removed from the additional section. 251 * @param edns: the edns data is stored here. Does not have to be initialised. 252 * @return: 0 on success. or an RCODE on an error. 253 * RCODE formerr if OPT in wrong section, and so on. 254 */ 255int parse_extract_edns(struct msg_parse* msg, struct edns_data* edns); 256 257/** 258 * If EDNS data follows a query section, extract it and initialize edns struct. 259 * @param pkt: the packet. position at start must be right after the query 260 * section. At end, right after EDNS data or no movement if failed. 261 * @param edns: the edns data allocated by the caller. Does not have to be 262 * initialised. 263 * @return: 0 on success, or an RCODE on error. 264 * RCODE formerr if OPT is badly formatted and so on. 265 */ 266int parse_edns_from_pkt(struct sldns_buffer* pkt, struct edns_data* edns); 267 268/** 269 * Calculate hash value for rrset in packet. 270 * @param pkt: the packet. 271 * @param dname: pointer to uncompressed dname, or compressed dname in packet. 272 * @param type: rrset type in host order. 273 * @param dclass: rrset class in network order. 274 * @param rrset_flags: rrset flags (same as packed_rrset flags). 275 * @return hash value 276 */ 277hashvalue_t pkt_hash_rrset(struct sldns_buffer* pkt, uint8_t* dname, uint16_t type, 278 uint16_t dclass, uint32_t rrset_flags); 279 280/** 281 * Lookup in msg hashtable to find a rrset. 282 * @param msg: with the hashtable. 283 * @param pkt: packet for compressed names. 284 * @param h: hash value 285 * @param rrset_flags: flags of rrset sought for. 286 * @param dname: name of rrset sought for. 287 * @param dnamelen: len of dname. 288 * @param type: rrset type, host order. 289 * @param dclass: rrset class, network order. 290 * @return NULL or the rrset_parse if found. 291 */ 292struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg, 293 struct sldns_buffer* pkt, hashvalue_t h, uint32_t rrset_flags, 294 uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass); 295 296/** 297 * Remove rrset from hash table. 298 * @param msg: with hashtable. 299 * @param rrset: with hash value and id info. 300 */ 301void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset); 302 303#endif /* UTIL_DATA_MSGPARSE_H */ 304