304 lines
11 KiB
C
304 lines
11 KiB
C
/*
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* util/data/msgparse.h - parse wireformat DNS messages.
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*
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* Copyright (c) 2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \file
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* Contains message parsing data structures.
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* These point back into the packet buffer.
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*
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* During parsing RRSIGS are put together with the rrsets they (claim to) sign.
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* This process works as follows:
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* o if RRSIG follows the data rrset, it is added to the rrset rrsig list.
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* o if no matching data rrset is found, the RRSIG becomes a new rrset.
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* o If the data rrset later follows the RRSIG
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* o See if the RRSIG rrset contains multiple types, and needs to
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* have the rrsig(s) for that data type split off.
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* o Put the data rr as data type in the rrset and rrsig in list.
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* o RRSIGs are allowed to move to a different section. The section of
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* the data item is used for the final rrset.
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* o multiple signatures over an RRset are possible.
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*
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* For queries of qtype=RRSIG, some special handling is needed, to avoid
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* splitting the RRSIG in the answer section.
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* o duplicate, not split, RRSIGs from the answer section, if qtype=RRSIG.
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* o check for doubles in the rrsig list when adding an RRSIG to data,
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* so that a data rrset is signed by RRSIGs with different rdata.
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* when qtype=RRSIG.
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* This will move the RRSIG from the answer section to sign the data further
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* in the packet (if possible). If then after that, more RRSIGs are found
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* that sign the data as well, doubles are removed.
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*/
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#ifndef UTIL_DATA_MSGPARSE_H
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#define UTIL_DATA_MSGPARSE_H
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#include "util/storage/lruhash.h"
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#include "sldns/pkthdr.h"
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#include "sldns/rrdef.h"
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struct sldns_buffer;
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struct rrset_parse;
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struct rr_parse;
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struct regional;
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/** number of buckets in parse rrset hash table. Must be power of 2. */
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#define PARSE_TABLE_SIZE 32
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/** Maximum TTL that is allowed. */
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extern time_t MAX_TTL;
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/** Minimum TTL that is allowed. */
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extern time_t MIN_TTL;
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/** Maximum Negative TTL that is allowed */
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extern time_t MAX_NEG_TTL;
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/** Negative cache time (for entries without any RRs.) */
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#define NORR_TTL 5 /* seconds */
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/**
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* Data stored in scratch pad memory during parsing.
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* Stores the data that will enter into the msgreply and packet result.
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*/
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struct msg_parse {
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/** id from message, network format. */
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uint16_t id;
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/** flags from message, host format. */
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uint16_t flags;
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/** count of RRs, host format */
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uint16_t qdcount;
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/** count of RRs, host format */
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uint16_t ancount;
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/** count of RRs, host format */
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uint16_t nscount;
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/** count of RRs, host format */
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uint16_t arcount;
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/** count of RRsets per section. */
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size_t an_rrsets;
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/** count of RRsets per section. */
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size_t ns_rrsets;
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/** count of RRsets per section. */
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size_t ar_rrsets;
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/** total number of rrsets found. */
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size_t rrset_count;
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/** query dname (pointer to start location in packet, NULL if none */
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uint8_t* qname;
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/** length of query dname in octets, 0 if none */
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size_t qname_len;
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/** query type, host order. 0 if qdcount=0 */
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uint16_t qtype;
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/** query class, host order. 0 if qdcount=0 */
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uint16_t qclass;
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/**
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* Hash table array used during parsing to lookup rrset types.
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* Based on name, type, class. Same hash value as in rrset cache.
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*/
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struct rrset_parse* hashtable[PARSE_TABLE_SIZE];
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/** linked list of rrsets that have been found (in order). */
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struct rrset_parse* rrset_first;
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/** last element of rrset list. */
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struct rrset_parse* rrset_last;
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};
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/**
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* Data stored for an rrset during parsing.
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*/
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struct rrset_parse {
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/** next in hash bucket */
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struct rrset_parse* rrset_bucket_next;
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/** next in list of all rrsets */
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struct rrset_parse* rrset_all_next;
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/** hash value of rrset */
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hashvalue_t hash;
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/** which section was it found in: one of
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* LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL
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*/
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sldns_pkt_section section;
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/** start of (possibly compressed) dname in packet */
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uint8_t* dname;
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/** length of the dname uncompressed wireformat */
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size_t dname_len;
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/** type, host order. */
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uint16_t type;
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/** class, network order. var name so that it is not a c++ keyword. */
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uint16_t rrset_class;
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/** the flags for the rrset, like for packedrrset */
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uint32_t flags;
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/** number of RRs in the rr list */
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size_t rr_count;
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/** sum of RR rdata sizes */
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size_t size;
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/** linked list of RRs in this rrset. */
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struct rr_parse* rr_first;
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/** last in list of RRs in this rrset. */
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struct rr_parse* rr_last;
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/** number of RRSIGs over this rrset. */
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size_t rrsig_count;
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/** linked list of RRsig RRs over this rrset. */
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struct rr_parse* rrsig_first;
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/** last in list of RRSIG RRs over this rrset. */
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struct rr_parse* rrsig_last;
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};
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/**
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* Data stored for an RR during parsing.
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*/
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struct rr_parse {
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/**
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* Pointer to the RR. Points to start of TTL value in the packet.
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* Rdata length and rdata follow it.
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* its dname, type and class are the same and stored for the rrset.
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*/
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uint8_t* ttl_data;
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/** true if ttl_data is not part of the packet, but elsewhere in mem.
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* Set for generated CNAMEs for DNAMEs. */
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int outside_packet;
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/** the length of the rdata if allocated (with no dname compression)*/
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size_t size;
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/** next in list of RRs. */
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struct rr_parse* next;
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};
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/** Check if label length is first octet of a compression pointer, pass u8. */
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#define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 )
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/** Calculate destination offset of a compression pointer. pass first and
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* second octets of the compression pointer. */
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#define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) )
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/** create a compression pointer to the given offset. */
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#define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset)))
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/** error codes, extended with EDNS, so > 15. */
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#define EDNS_RCODE_BADVERS 16 /** bad EDNS version */
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/** largest valid compression offset */
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#define PTR_MAX_OFFSET 0x3fff
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/**
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* EDNS data storage
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* EDNS rdata is ignored.
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*/
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struct edns_data {
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/** if EDNS OPT record was present */
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int edns_present;
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/** Extended RCODE */
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uint8_t ext_rcode;
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/** The EDNS version number */
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uint8_t edns_version;
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/** the EDNS bits field from ttl (host order): Z */
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uint16_t bits;
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/** UDP reassembly size. */
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uint16_t udp_size;
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};
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/**
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* Obtain size in the packet of an rr type, that is before dname type.
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* Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types.
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* @param rdf: the rdf type from the descriptor.
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* @return: size in octets. 0 on failure.
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*/
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size_t get_rdf_size(sldns_rdf_type rdf);
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/**
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* Parse the packet.
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* @param pkt: packet, position at call must be at start of packet.
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* at end position is after packet.
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* @param msg: where to store results.
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* @param region: how to alloc results.
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* @return: 0 if OK, or rcode on error.
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*/
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int parse_packet(struct sldns_buffer* pkt, struct msg_parse* msg,
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struct regional* region);
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/**
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* After parsing the packet, extract EDNS data from packet.
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* If not present this is noted in the data structure.
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* If a parse error happens, an error code is returned.
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*
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* Quirks:
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* o ignores OPT rdata.
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* o ignores OPT owner name.
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* o ignores extra OPT records, except the last one in the packet.
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*
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* @param msg: parsed message structure. Modified on exit, if EDNS was present
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* it is removed from the additional section.
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* @param edns: the edns data is stored here. Does not have to be initialised.
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* @return: 0 on success. or an RCODE on an error.
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* RCODE formerr if OPT in wrong section, and so on.
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*/
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int parse_extract_edns(struct msg_parse* msg, struct edns_data* edns);
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/**
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* If EDNS data follows a query section, extract it and initialize edns struct.
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* @param pkt: the packet. position at start must be right after the query
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* section. At end, right after EDNS data or no movement if failed.
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* @param edns: the edns data allocated by the caller. Does not have to be
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* initialised.
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* @return: 0 on success, or an RCODE on error.
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* RCODE formerr if OPT is badly formatted and so on.
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*/
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int parse_edns_from_pkt(struct sldns_buffer* pkt, struct edns_data* edns);
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/**
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* Calculate hash value for rrset in packet.
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* @param pkt: the packet.
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* @param dname: pointer to uncompressed dname, or compressed dname in packet.
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* @param type: rrset type in host order.
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* @param dclass: rrset class in network order.
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* @param rrset_flags: rrset flags (same as packed_rrset flags).
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* @return hash value
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*/
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hashvalue_t pkt_hash_rrset(struct sldns_buffer* pkt, uint8_t* dname, uint16_t type,
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uint16_t dclass, uint32_t rrset_flags);
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/**
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* Lookup in msg hashtable to find a rrset.
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* @param msg: with the hashtable.
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* @param pkt: packet for compressed names.
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* @param h: hash value
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* @param rrset_flags: flags of rrset sought for.
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* @param dname: name of rrset sought for.
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* @param dnamelen: len of dname.
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* @param type: rrset type, host order.
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* @param dclass: rrset class, network order.
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* @return NULL or the rrset_parse if found.
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*/
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struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg,
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struct sldns_buffer* pkt, hashvalue_t h, uint32_t rrset_flags,
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uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass);
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/**
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* Remove rrset from hash table.
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* @param msg: with hashtable.
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* @param rrset: with hash value and id info.
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*/
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void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset);
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#endif /* UTIL_DATA_MSGPARSE_H */
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