unbound/util/data/msgparse.h

   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 */