/*
* util/data/msgparse.h - parse wireformat DNS messages.
*
* Copyright (c) 2007, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \file
* Contains message parsing data structures.
* These point back into the packet buffer.
*
* During parsing RRSIGS are put together with the rrsets they (claim to) sign.
* This process works as follows:
* o if RRSIG follows the data rrset, it is added to the rrset rrsig list.
* o if no matching data rrset is found, the RRSIG becomes a new rrset.
* o If the data rrset later follows the RRSIG
* o See if the RRSIG rrset contains multiple types, and needs to
* have the rrsig(s) for that data type split off.
* o Put the data rr as data type in the rrset and rrsig in list.
* o RRSIGs are allowed to move to a different section. The section of
* the data item is used for the final rrset.
* o multiple signatures over an RRset are possible.
*
* For queries of qtype=RRSIG, some special handling is needed, to avoid
* splitting the RRSIG in the answer section.
* o duplicate, not split, RRSIGs from the answer section, if qtype=RRSIG.
* o check for doubles in the rrsig list when adding an RRSIG to data,
* so that a data rrset is signed by RRSIGs with different rdata.
* when qtype=RRSIG.
* This will move the RRSIG from the answer section to sign the data further
* in the packet (if possible). If then after that, more RRSIGs are found
* that sign the data as well, doubles are removed.
*/
#ifndef UTIL_DATA_MSGPARSE_H
#define UTIL_DATA_MSGPARSE_H
#include "util/storage/lruhash.h"
#include "sldns/pkthdr.h"
#include "sldns/rrdef.h"
struct sldns_buffer;
struct rrset_parse;
struct rr_parse;
struct regional;
struct edns_option;
/** number of buckets in parse rrset hash table. Must be power of 2. */
#define PARSE_TABLE_SIZE 32
/** Maximum TTL that is allowed. */
extern time_t MAX_TTL;
/** Minimum TTL that is allowed. */
extern time_t MIN_TTL;
/** Maximum Negative TTL that is allowed */
extern time_t MAX_NEG_TTL;
/** Negative cache time (for entries without any RRs.) */
#define NORR_TTL 5 /* seconds */
/**
* Data stored in scratch pad memory during parsing.
* Stores the data that will enter into the msgreply and packet result.
*/
struct msg_parse {
/** id from message, network format. */
uint16_t id;
/** flags from message, host format. */
uint16_t flags;
/** count of RRs, host format */
uint16_t qdcount;
/** count of RRs, host format */
uint16_t ancount;
/** count of RRs, host format */
uint16_t nscount;
/** count of RRs, host format */
uint16_t arcount;
/** count of RRsets per section. */
size_t an_rrsets;
/** count of RRsets per section. */
size_t ns_rrsets;
/** count of RRsets per section. */
size_t ar_rrsets;
/** total number of rrsets found. */
size_t rrset_count;
/** query dname (pointer to start location in packet, NULL if none */
uint8_t* qname;
/** length of query dname in octets, 0 if none */
size_t qname_len;
/** query type, host order. 0 if qdcount=0 */
uint16_t qtype;
/** query class, host order. 0 if qdcount=0 */
uint16_t qclass;
/**
* Hash table array used during parsing to lookup rrset types.
* Based on name, type, class. Same hash value as in rrset cache.
*/
struct rrset_parse* hashtable[PARSE_TABLE_SIZE];
/** linked list of rrsets that have been found (in order). */
struct rrset_parse* rrset_first;
/** last element of rrset list. */
struct rrset_parse* rrset_last;
};
/**
* Data stored for an rrset during parsing.
*/
struct rrset_parse {
/** next in hash bucket */
struct rrset_parse* rrset_bucket_next;
/** next in list of all rrsets */
struct rrset_parse* rrset_all_next;
/** hash value of rrset */
hashvalue_type hash;
/** which section was it found in: one of
* LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL
*/
sldns_pkt_section section;
/** start of (possibly compressed) dname in packet */
uint8_t* dname;
/** length of the dname uncompressed wireformat */
size_t dname_len;
/** type, host order. */
uint16_t type;
/** class, network order. var name so that it is not a c++ keyword. */
uint16_t rrset_class;
/** the flags for the rrset, like for packedrrset */
uint32_t flags;
/** number of RRs in the rr list */
size_t rr_count;
/** sum of RR rdata sizes */
size_t size;
/** linked list of RRs in this rrset. */
struct rr_parse* rr_first;
/** last in list of RRs in this rrset. */
struct rr_parse* rr_last;
/** number of RRSIGs over this rrset. */
size_t rrsig_count;
/** linked list of RRsig RRs over this rrset. */
struct rr_parse* rrsig_first;
/** last in list of RRSIG RRs over this rrset. */
struct rr_parse* rrsig_last;
};
/**
* Data stored for an RR during parsing.
*/
struct rr_parse {
/**
* Pointer to the RR. Points to start of TTL value in the packet.
* Rdata length and rdata follow it.
* its dname, type and class are the same and stored for the rrset.
*/
uint8_t* ttl_data;
/** true if ttl_data is not part of the packet, but elsewhere in mem.
* Set for generated CNAMEs for DNAMEs. */
int outside_packet;
/** the length of the rdata if allocated (with no dname compression)*/
size_t size;
/** next in list of RRs. */
struct rr_parse* next;
};
/** Check if label length is first octet of a compression pointer, pass u8. */
#define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 )
/** Calculate destination offset of a compression pointer. pass first and
* second octets of the compression pointer. */
#define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) )
/** create a compression pointer to the given offset. */
#define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset)))
/** error codes, extended with EDNS, so > 15. */
#define EDNS_RCODE_BADVERS 16 /** bad EDNS version */
/** largest valid compression offset */
#define PTR_MAX_OFFSET 0x3fff
/**
* EDNS data storage
* rdata is parsed in a list (has accessor functions). allocated in a
* region.
*/
struct edns_data {
/** if EDNS OPT record was present */
int edns_present;
/** Extended RCODE */
uint8_t ext_rcode;
/** The EDNS version number */
uint8_t edns_version;
/** the EDNS bits field from ttl (host order): Z */
uint16_t bits;
/** UDP reassembly size. */
uint16_t udp_size;
/** rdata element list, or NULL if none */
struct edns_option* opt_list;
};
/**
* EDNS option
*/
struct edns_option {
/** next item in list */
struct edns_option* next;
/** type of this edns option */
uint16_t opt_code;
/** length of this edns option (cannot exceed uint16 in encoding) */
size_t opt_len;
/** data of this edns option; allocated in region, or NULL if len=0 */
uint8_t* opt_data;
};
/**
* Obtain size in the packet of an rr type, that is before dname type.
* Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types.
* @param rdf: the rdf type from the descriptor.
* @return: size in octets. 0 on failure.
*/
size_t get_rdf_size(sldns_rdf_type rdf);
/**
* Parse the packet.
* @param pkt: packet, position at call must be at start of packet.
* at end position is after packet.
* @param msg: where to store results.
* @param region: how to alloc results.
* @return: 0 if OK, or rcode on error.
*/
int parse_packet(struct sldns_buffer* pkt, struct msg_parse* msg,
struct regional* region);
/**
* After parsing the packet, extract EDNS data from packet.
* If not present this is noted in the data structure.
* If a parse error happens, an error code is returned.
*
* Quirks:
* o ignores OPT rdata.
* o ignores OPT owner name.
* o ignores extra OPT records, except the last one in the packet.
*
* @param msg: parsed message structure. Modified on exit, if EDNS was present
* it is removed from the additional section.
* @param edns: the edns data is stored here. Does not have to be initialised.
* @param region: region to alloc results in (edns option contents)
* @return: 0 on success. or an RCODE on an error.
* RCODE formerr if OPT in wrong section, and so on.
*/
int parse_extract_edns(struct msg_parse* msg, struct edns_data* edns,
struct regional* region);
/**
* If EDNS data follows a query section, extract it and initialize edns struct.
* @param pkt: the packet. position at start must be right after the query
* section. At end, right after EDNS data or no movement if failed.
* @param edns: the edns data allocated by the caller. Does not have to be
* initialised.
* @param region: region to alloc results in (edns option contents)
* @return: 0 on success, or an RCODE on error.
* RCODE formerr if OPT is badly formatted and so on.
*/
int parse_edns_from_pkt(struct sldns_buffer* pkt, struct edns_data* edns,
struct regional* region);
/**
* Calculate hash value for rrset in packet.
* @param pkt: the packet.
* @param dname: pointer to uncompressed dname, or compressed dname in packet.
* @param type: rrset type in host order.
* @param dclass: rrset class in network order.
* @param rrset_flags: rrset flags (same as packed_rrset flags).
* @return hash value
*/
hashvalue_type pkt_hash_rrset(struct sldns_buffer* pkt, uint8_t* dname,
uint16_t type, uint16_t dclass, uint32_t rrset_flags);
/**
* Lookup in msg hashtable to find a rrset.
* @param msg: with the hashtable.
* @param pkt: packet for compressed names.
* @param h: hash value
* @param rrset_flags: flags of rrset sought for.
* @param dname: name of rrset sought for.
* @param dnamelen: len of dname.
* @param type: rrset type, host order.
* @param dclass: rrset class, network order.
* @return NULL or the rrset_parse if found.
*/
struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg,
struct sldns_buffer* pkt, hashvalue_type h, uint32_t rrset_flags,
uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass);
/**
* Remove rrset from hash table.
* @param msg: with hashtable.
* @param rrset: with hash value and id info.
*/
void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset);
/**
* Log the edns options in the edns option list.
* @param level: the verbosity level.
* @param info_str: the informational string to be printed before the options.
* @param list: the edns option list.
*/
void log_edns_opt_list(enum verbosity_value level, const char* info_str,
struct edns_option* list);
#endif /* UTIL_DATA_MSGPARSE_H */
