msgparse.h revision 249140
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 LIMITED 25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE 27 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33 * 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/packet.h> 67struct rrset_parse; 68struct rr_parse; 69struct regional; 70 71/** number of buckets in parse rrset hash table. Must be power of 2. */ 72#define PARSE_TABLE_SIZE 32 73/** Maximum TTL that is allowed. */ 74extern uint32_t MAX_TTL; 75/** Minimum TTL that is allowed. */ 76extern uint32_t MIN_TTL; 77/** Negative cache time (for entries without any RRs.) */ 78#define NORR_TTL 5 /* seconds */ 79 80/** 81 * Data stored in scratch pad memory during parsing. 82 * Stores the data that will enter into the msgreply and packet result. 83 */ 84struct msg_parse { 85 /** id from message, network format. */ 86 uint16_t id; 87 /** flags from message, host format. */ 88 uint16_t flags; 89 /** count of RRs, host format */ 90 uint16_t qdcount; 91 /** count of RRs, host format */ 92 uint16_t ancount; 93 /** count of RRs, host format */ 94 uint16_t nscount; 95 /** count of RRs, host format */ 96 uint16_t arcount; 97 /** count of RRsets per section. */ 98 size_t an_rrsets; 99 /** count of RRsets per section. */ 100 size_t ns_rrsets; 101 /** count of RRsets per section. */ 102 size_t ar_rrsets; 103 /** total number of rrsets found. */ 104 size_t rrset_count; 105 106 /** query dname (pointer to start location in packet, NULL if none */ 107 uint8_t* qname; 108 /** length of query dname in octets, 0 if none */ 109 size_t qname_len; 110 /** query type, host order. 0 if qdcount=0 */ 111 uint16_t qtype; 112 /** query class, host order. 0 if qdcount=0 */ 113 uint16_t qclass; 114 115 /** 116 * Hash table array used during parsing to lookup rrset types. 117 * Based on name, type, class. Same hash value as in rrset cache. 118 */ 119 struct rrset_parse* hashtable[PARSE_TABLE_SIZE]; 120 121 /** linked list of rrsets that have been found (in order). */ 122 struct rrset_parse* rrset_first; 123 /** last element of rrset list. */ 124 struct rrset_parse* rrset_last; 125}; 126 127/** 128 * Data stored for an rrset during parsing. 129 */ 130struct rrset_parse { 131 /** next in hash bucket */ 132 struct rrset_parse* rrset_bucket_next; 133 /** next in list of all rrsets */ 134 struct rrset_parse* rrset_all_next; 135 /** hash value of rrset */ 136 hashvalue_t hash; 137 /** which section was it found in: one of 138 * LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL 139 */ 140 ldns_pkt_section section; 141 /** start of (possibly compressed) dname in packet */ 142 uint8_t* dname; 143 /** length of the dname uncompressed wireformat */ 144 size_t dname_len; 145 /** type, host order. */ 146 uint16_t type; 147 /** class, network order. var name so that it is not a c++ keyword. */ 148 uint16_t rrset_class; 149 /** the flags for the rrset, like for packedrrset */ 150 uint32_t flags; 151 /** number of RRs in the rr list */ 152 size_t rr_count; 153 /** sum of RR rdata sizes */ 154 size_t size; 155 /** linked list of RRs in this rrset. */ 156 struct rr_parse* rr_first; 157 /** last in list of RRs in this rrset. */ 158 struct rr_parse* rr_last; 159 /** number of RRSIGs over this rrset. */ 160 size_t rrsig_count; 161 /** linked list of RRsig RRs over this rrset. */ 162 struct rr_parse* rrsig_first; 163 /** last in list of RRSIG RRs over this rrset. */ 164 struct rr_parse* rrsig_last; 165}; 166 167/** 168 * Data stored for an RR during parsing. 169 */ 170struct rr_parse { 171 /** 172 * Pointer to the RR. Points to start of TTL value in the packet. 173 * Rdata length and rdata follow it. 174 * its dname, type and class are the same and stored for the rrset. 175 */ 176 uint8_t* ttl_data; 177 /** true if ttl_data is not part of the packet, but elsewhere in mem. 178 * Set for generated CNAMEs for DNAMEs. */ 179 int outside_packet; 180 /** the length of the rdata if allocated (with no dname compression)*/ 181 size_t size; 182 /** next in list of RRs. */ 183 struct rr_parse* next; 184}; 185 186/** Check if label length is first octet of a compression pointer, pass u8. */ 187#define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 ) 188/** Calculate destination offset of a compression pointer. pass first and 189 * second octets of the compression pointer. */ 190#define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) ) 191/** create a compression pointer to the given offset. */ 192#define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset))) 193 194/** error codes, extended with EDNS, so > 15. */ 195#define EDNS_RCODE_BADVERS 16 /** bad EDNS version */ 196/** largest valid compression offset */ 197#define PTR_MAX_OFFSET 0x3fff 198 199/** 200 * EDNS data storage 201 * EDNS rdata is ignored. 202 */ 203struct edns_data { 204 /** if EDNS OPT record was present */ 205 int edns_present; 206 /** Extended RCODE */ 207 uint8_t ext_rcode; 208 /** The EDNS version number */ 209 uint8_t edns_version; 210 /** the EDNS bits field from ttl (host order): Z */ 211 uint16_t bits; 212 /** UDP reassembly size. */ 213 uint16_t udp_size; 214}; 215 216/** 217 * Obtain size in the packet of an rr type, that is before dname type. 218 * Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types. 219 * @param rdf: the rdf type from the descriptor. 220 * @return: size in octets. 0 on failure. 221 */ 222size_t get_rdf_size(ldns_rdf_type rdf); 223 224/** 225 * Parse the packet. 226 * @param pkt: packet, position at call must be at start of packet. 227 * at end position is after packet. 228 * @param msg: where to store results. 229 * @param region: how to alloc results. 230 * @return: 0 if OK, or rcode on error. 231 */ 232int parse_packet(ldns_buffer* pkt, struct msg_parse* msg, 233 struct regional* region); 234 235/** 236 * After parsing the packet, extract EDNS data from packet. 237 * If not present this is noted in the data structure. 238 * If a parse error happens, an error code is returned. 239 * 240 * Quirks: 241 * o ignores OPT rdata. 242 * o ignores OPT owner name. 243 * o ignores extra OPT records, except the last one in the packet. 244 * 245 * @param msg: parsed message structure. Modified on exit, if EDNS was present 246 * it is removed from the additional section. 247 * @param edns: the edns data is stored here. Does not have to be initialised. 248 * @return: 0 on success. or an RCODE on an error. 249 * RCODE formerr if OPT in wrong section, and so on. 250 */ 251int parse_extract_edns(struct msg_parse* msg, struct edns_data* edns); 252 253/** 254 * If EDNS data follows a query section, extract it and initialize edns struct. 255 * @param pkt: the packet. position at start must be right after the query 256 * section. At end, right after EDNS data or no movement if failed. 257 * @param edns: the edns data allocated by the caller. Does not have to be 258 * initialised. 259 * @return: 0 on success, or an RCODE on error. 260 * RCODE formerr if OPT is badly formatted and so on. 261 */ 262int parse_edns_from_pkt(ldns_buffer* pkt, struct edns_data* edns); 263 264/** 265 * Calculate hash value for rrset in packet. 266 * @param pkt: the packet. 267 * @param dname: pointer to uncompressed dname, or compressed dname in packet. 268 * @param type: rrset type in host order. 269 * @param dclass: rrset class in network order. 270 * @param rrset_flags: rrset flags (same as packed_rrset flags). 271 * @return hash value 272 */ 273hashvalue_t pkt_hash_rrset(ldns_buffer* pkt, uint8_t* dname, uint16_t type, 274 uint16_t dclass, uint32_t rrset_flags); 275 276/** 277 * Lookup in msg hashtable to find a rrset. 278 * @param msg: with the hashtable. 279 * @param pkt: packet for compressed names. 280 * @param h: hash value 281 * @param rrset_flags: flags of rrset sought for. 282 * @param dname: name of rrset sought for. 283 * @param dnamelen: len of dname. 284 * @param type: rrset type, host order. 285 * @param dclass: rrset class, network order. 286 * @return NULL or the rrset_parse if found. 287 */ 288struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg, 289 ldns_buffer* pkt, hashvalue_t h, uint32_t rrset_flags, 290 uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass); 291 292/** 293 * Remove rrset from hash table. 294 * @param msg: with hashtable. 295 * @param rrset: with hash value and id info. 296 */ 297void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset); 298 299#endif /* UTIL_DATA_MSGPARSE_H */ 300