ldns(3)

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🎀 ldns(3) 🎀

okay so bestie, welcome to ldns(3), the Library Functions Manual, and today we're doing the resource-record corner of ldns 🦋 — the actual DNS types, the classes, the type codes, all of it. buckle up, it's giving ✨library lore✨.

💖 NAME 💖

these are the types that represent dns resource records, periodt:

  • ldns_rr
  • ldns_rr_class
  • ldns_rr_type
  • ldns_rr_compress
  • ldns_rr_list

🌸 SYNOPSIS 🌸

like, include these first, obviously:

#include <stdint.h>
#include <stdbool.h>

#include <ldns/ldns.h>

✨ DESCRIPTION ✨

ldns_rr

so Resource Record — this is the basic DNS element that contains actual data 👑 no cap, everything else is kind of built on top of this one.

From RFC1035:

3.2.1. Format

All RRs have the same top level format shown below:

                                    1  1  1  1  1  1
      0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                                               |
    /                                               /
    /                      NAME                     /
    |                                               |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                      TYPE                     |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                     CLASS                     |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                      TTL                      |
    |                                               |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                   RDLENGTH                    |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
    /                     RDATA                     /
    /                                               /
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

where:

NAME            an owner name, i.e., the name of the node to which this
                resource record pertains.

TYPE            two octets containing one of the RR TYPE codes.

CLASS           two octets containing one of the RR CLASS codes.

TTL             a 32 bit signed integer that specifies the time interval
                that the resource record may be cached before the source
                of the information should again be consulted. Zero
                values are interpreted to mean that the RR can only be
                used for the transaction in progress, and should not be
                cached.  For example, SOA records are always distributed
                with a zero TTL to prohibit caching.  Zero values can
                also be used for extremely volatile data.

RDLENGTH        an unsigned 16 bit integer that specifies the length in
                octets of the RDATA field.

RDATA           a variable length string of octets that describes the
                resource.  The format of this information varies
                according to the TYPE and CLASS of the resource record.

the actual amount and type of rdata fields depend on the RR type of the RR, and you can go find them with the \ref ldns_rr_descriptor functions 💅

struct ldns_struct_rr
{
     Owner name, uncompressed:
     ldns_rdf  *_owner;
     Time to live:
     uint32_t  _ttl;
     Number of data fields:
     size_t            _rd_count;
     the type of the RR. A, MX etc.:
     ldns_rr_type   _rr_type;
     Class of the resource record.:
     ldns_rr_class  _rr_class;
     /* everything in the rdata is in network order */
     The array of rdata's:
     ldns_rdf   **_rdata_fields;
     /**  question rr [it would be nicer if thous is after _rd_count]
           ABI change: Fix this in next major release
      */
     bool      _rr_question;
};
typedef struct ldns_struct_rr ldns_rr;

ldns_rr_class

the different RR classes 🫶

enum ldns_enum_rr_class
{
     the Internet:
     LDNS_RR_CLASS_IN    = 1,
     Chaos class:
     LDNS_RR_CLASS_CH    = 3,
     Hesiod (Dyer 87):
     LDNS_RR_CLASS_HS    = 4,
    None class, dynamic update:
    LDNS_RR_CLASS_NONE      = 254,
     Any class:
     LDNS_RR_CLASS_ANY   = 255,

     LDNS_RR_CLASS_FIRST     = 0,
     LDNS_RR_CLASS_LAST      = 65535,
     LDNS_RR_CLASS_COUNT     = LDNS_RR_CLASS_LAST - LDNS_RR_CLASS_FIRST + 1
};
typedef enum ldns_enum_rr_class ldns_rr_class;

ldns_rr_type

the different RR types 🌈 and yes it is long, we're not skimming, every single one of these gets its moment:

enum ldns_enum_rr_type
{
     a host address:
     LDNS_RR_TYPE_A = 1,
     an authoritative name server:
     LDNS_RR_TYPE_NS = 2,
     a mail destination (Obsolete - use MX):
     LDNS_RR_TYPE_MD = 3,
     a mail forwarder (Obsolete - use MX):
     LDNS_RR_TYPE_MF = 4,
     the canonical name for an alias:
     LDNS_RR_TYPE_CNAME = 5,
     marks the start of a zone of authority:
     LDNS_RR_TYPE_SOA = 6,
     a mailbox domain name (EXPERIMENTAL):
     LDNS_RR_TYPE_MB = 7,
     a mail group member (EXPERIMENTAL):
     LDNS_RR_TYPE_MG = 8,
     a mail rename domain name (EXPERIMENTAL):
     LDNS_RR_TYPE_MR = 9,
     a null RR (EXPERIMENTAL):
     LDNS_RR_TYPE_NULL = 10,
     a well known service description:
     LDNS_RR_TYPE_WKS = 11,
     a domain name pointer:
     LDNS_RR_TYPE_PTR = 12,
     host information:
     LDNS_RR_TYPE_HINFO = 13,
     mailbox or mail list information:
     LDNS_RR_TYPE_MINFO = 14,
     mail exchange:
     LDNS_RR_TYPE_MX = 15,
     text strings:
     LDNS_RR_TYPE_TXT = 16,
     RFC1183:
     LDNS_RR_TYPE_RP = 17,
     RFC1183:
     LDNS_RR_TYPE_AFSDB = 18,
     RFC1183:
     LDNS_RR_TYPE_X25 = 19,
     RFC1183:
     LDNS_RR_TYPE_ISDN = 20,
     RFC1183:
     LDNS_RR_TYPE_RT = 21,
     RFC1706:
     LDNS_RR_TYPE_NSAP = 22,
     RFC1348:
     LDNS_RR_TYPE_NSAP_PTR = 23,
     2535typecode:
     LDNS_RR_TYPE_SIG = 24,
     2535typecode:
     LDNS_RR_TYPE_KEY = 25,
     RFC2163:
     LDNS_RR_TYPE_PX = 26,
     RFC1712:
     LDNS_RR_TYPE_GPOS = 27,
     ipv6 address:
     LDNS_RR_TYPE_AAAA = 28,
     LOC record  RFC1876:
     LDNS_RR_TYPE_LOC = 29,
     2535typecode:
     LDNS_RR_TYPE_NXT = 30,
     draft-ietf-nimrod-dns-01.txt:
     LDNS_RR_TYPE_EID = 31,
     draft-ietf-nimrod-dns-01.txt:
     LDNS_RR_TYPE_NIMLOC = 32,
     SRV record RFC2782:
     LDNS_RR_TYPE_SRV = 33,
     http://www.jhsoft.com/rfc/af-saa-0069.000.rtf:
     LDNS_RR_TYPE_ATMA = 34,
     RFC2915:
     LDNS_RR_TYPE_NAPTR = 35,
     RFC2230:
     LDNS_RR_TYPE_KX = 36,
     RFC2538:
     LDNS_RR_TYPE_CERT = 37,
     RFC2874:
     LDNS_RR_TYPE_A6 = 38,
     RFC2672:
     LDNS_RR_TYPE_DNAME = 39,
     dnsind-kitchen-sink-02.txt:
     LDNS_RR_TYPE_SINK = 40,
     OPT record RFC 6891:
     LDNS_RR_TYPE_OPT = 41,
     RFC3123:
     LDNS_RR_TYPE_APL = 42,
     RFC4034, RFC3658:
     LDNS_RR_TYPE_DS = 43,
     SSH Key Fingerprint:
     LDNS_RR_TYPE_SSHFP = 44, /* RFC 4255 */
     IPsec Key:
     LDNS_RR_TYPE_IPSECKEY = 45, /* RFC 4025 */
     DNSSEC:
     LDNS_RR_TYPE_RRSIG = 46, /* RFC 4034 */
     LDNS_RR_TYPE_NSEC = 47, /* RFC 4034 */
     LDNS_RR_TYPE_DNSKEY = 48, /* RFC 4034 */

     LDNS_RR_TYPE_DHCID = 49, /* RFC 4701 */
     /* NSEC3 */
     LDNS_RR_TYPE_NSEC3 = 50, /* RFC 5155 */
     LDNS_RR_TYPE_NSEC3PARAM = 51, /* RFC 5155 */
     LDNS_RR_TYPE_NSEC3PARAMS = 51,
     LDNS_RR_TYPE_TLSA = 52, /* RFC 6698 */
     LDNS_RR_TYPE_SMIMEA = 53, /* RFC 8162 */

     LDNS_RR_TYPE_HIP = 55, /* RFC 5205 */

     draft-reid-dnsext-zs:
     LDNS_RR_TYPE_NINFO = 56,
     draft-reid-dnsext-rkey:
     LDNS_RR_TYPE_RKEY = 57,
        draft-ietf-dnsop-trust-history:
        LDNS_RR_TYPE_TALINK = 58,
     LDNS_RR_TYPE_CDS = 59, /* RFC 7344 */
     LDNS_RR_TYPE_CDNSKEY = 60, /* RFC 7344 */
     LDNS_RR_TYPE_OPENPGPKEY = 61, /* RFC 7929 */
     LDNS_RR_TYPE_CSYNC = 62, /* RFC 7477 */
     LDNS_RR_TYPE_ZONEMD = 63, /* RFC 8976 */
     LDNS_RR_TYPE_SVCB = 64, /* RFC 9460 */
     LDNS_RR_TYPE_HTTPS = 65, /* RFC 9460 */
     LDNS_RR_TYPE_DSYNC = 66, /* RFC 9859 */
     LDNS_RR_TYPE_HHIT = 67, /* draft-ietf-drip-registries-28 */
     LDNS_RR_TYPE_BRID = 68, /* draft-ietf-drip-registries-28 */

     LDNS_RR_TYPE_SPF = 99, /* RFC 4408 */

     LDNS_RR_TYPE_UINFO = 100,
     LDNS_RR_TYPE_UID = 101,
     LDNS_RR_TYPE_GID = 102,
     LDNS_RR_TYPE_UNSPEC = 103,

     LDNS_RR_TYPE_NID = 104, /* RFC 6742 */
     LDNS_RR_TYPE_L32 = 105, /* RFC 6742 */
     LDNS_RR_TYPE_L64 = 106, /* RFC 6742 */
     LDNS_RR_TYPE_LP = 107, /* RFC 6742 */

     LDNS_RR_TYPE_EUI48 = 108, /* RFC 7043 */
     LDNS_RR_TYPE_EUI64 = 109, /* RFC 7043 */

     LDNS_RR_TYPE_NXNAME = 128, /* RFC 9824 */

...so yeah, the enum's still going, bestie, and honestly it's giving encyclopedia energy 💅 here's the rest of ldns_enum_rr_type, no cap, every single value:

LDNS_RR_TYPE_TKEY = 249, /* RFC 2930 */
LDNS_RR_TYPE_TSIG = 250,
LDNS_RR_TYPE_IXFR = 251,
LDNS_RR_TYPE_AXFR = 252,
/* A request for mailbox-related records (MB, MG or MR): */
LDNS_RR_TYPE_MAILB = 253,
/* A request for mail agent RRs (Obsolete - see MX): */
LDNS_RR_TYPE_MAILA = 254,
/* any type (wildcard): */
LDNS_RR_TYPE_ANY = 255,
LDNS_RR_TYPE_URI = 256, /* RFC 7553 */
LDNS_RR_TYPE_CAA = 257, /* RFC 6844 */
LDNS_RR_TYPE_AVC = 258, /* Cisco's DNS-AS RR, see www.dns-as.org */
LDNS_RR_TYPE_DOA = 259, /* draft-durand-doa-over-dns */

/* RFC 8777 */
LDNS_RR_TYPE_AMTRELAY = 260,

/* RFC 9606 */
LDNS_RR_TYPE_RESINFO = 261,

/* https://iana.org/assignments/dns-parameters/WALLET/wallet-completed-template */
LDNS_RR_TYPE_WALLET = 262,

/* https://www.iana.org/assignments/dns-parameters/CLA/cla-completed-template */
LDNS_RR_TYPE_CLA = 263,

/* https://www.iana.org/assignments/dns-parameters/IPN/ipn-completed-template */
LDNS_RR_TYPE_IPN = 264,

/* DNSSEC Trust Authorities: */
LDNS_RR_TYPE_TA = 32768,
/* RFC 4431, 5074, DNSSEC Lookaside Validation */
LDNS_RR_TYPE_DLV = 32769,

/* type codes from nsec3 experimental phase
LDNS_RR_TYPE_NSEC3 = 65324,
LDNS_RR_TYPE_NSEC3PARAMS = 65325, */
LDNS_RR_TYPE_FIRST = 0,
LDNS_RR_TYPE_LAST = 65535,
LDNS_RR_TYPE_COUNT = LDNS_RR_TYPE_LAST - LDNS_RR_TYPE_FIRST + 1
};
typedef enum ldns_enum_rr_type ldns_rr_type;

ngl a few things to clock here 🔍 LDNS_RR_TYPE_MAILB is the mailbox-records ask (MB, MG or MR), and LDNS_RR_TYPE_MAILA is the mail-agent-RR ask that's flagged Obsolete - see MX. LDNS_RR_TYPE_ANY = 255 is the wildcard "gimme everything" type. And yes the source really does hang a lone * off the RFC 8777 note, so we're keeping it, it's part of the lore 🎀

Also: the NSEC3 / NSEC3PARAMS pair (65324 and 65325) lives inside a comment — those are the type codes from the nsec3 experimental phase, so they're not actually compiled in. Periodt. LDNS_RR_TYPE_FIRST is 0, LDNS_RR_TYPE_LAST is 65535, and LDNS_RR_TYPE_COUNT is literally defined as LDNS_RR_TYPE_LAST - LDNS_RR_TYPE_FIRST + 1. Math ate. ✨

🌈 ldns_rr_compress 🌈

This lil enum is just the "are we allowed to compress this or not" switch:

enum ldns_enum_rr_compress
{
    /* compression is allowed: */
    LDNS_RR_COMPRESS,
    LDNS_RR_NO_COMPRESS
};
typedef enum ldns_enum_rr_compress ldns_rr_compress;

So LDNS_RR_COMPRESS = compression is allowed, LDNS_RR_NO_COMPRESS = it is not. Simple as. 🦋

🎀 ldns_rr_list 🎀

A List or Set of Resource Records — it contains a list of rr's. Lowkey important caveat though, straight from the source: no official RFC-like checks are made. 🙈

struct ldns_struct_rr_list
{
    size_t _rr_count;
    size_t _rr_capacity;
    ldns_rr **_rrs;
};
typedef struct ldns_struct_rr_list ldns_rr_list;

That's the whole struct, bestie — a count, a capacity, and a pointer to pointers of ldns_rr. Chef's kiss. 👑

👑 AUTHOR 👑

The ldns team at NLnet Labs.

🫶 REPORTING BUGS 🫶

Found a bug? Don't be shy, tell the girlies:

Copyright (c) 2004 - 2006 NLnet Labs.

Licensed under the BSD License. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

fr fr, no warranty. None. Not even the "it should at least work" kind. 💀

🌸 SEE ALSO 🌸

the way that this list is so long, she ate 💅: ldns_rr_new, ldns_rr_new_frm_type, ldns_rr_new_frm_str, ldns_rr_new_frm_fp, ldns_rr_free, ldns_rr_print, ldns_rr_set_owner, ldns_rr_set_ttl, ldns_rr_set_type, ldns_rr_set_rd_count, ldns_rr_set_class, ldns_rr_set_rdf, ldns_rr_push_rdf, ldns_rr_pop_rdf, ldns_rr_rdf, ldns_rr_owner, ldns_rr_rd_count, ldns_rr_ttl, ldns_rr_get_class, ldns_rr_list_rr_count, ldns_rr_list_set_rr_count, ldns_rr_list_new, ldns_rr_list_free, ldns_rr_list_cat, ldns_rr_list_push_rr, ldns_rr_list_pop_rr, ldns_is_rrset, ldns_rr_set_push_rr, ldns_rr_set_pop_rr, ldns_get_rr_class_by_name, ldns_get_rr_type_by_name, ldns_rr_list_clone, ldns_rr_list_sort, ldns_rr_compare, ldns_rr_compare_ds, ldns_rr_uncompressed_size, ldns_rr2canonical, ldns_rr_label_count, ldns_is_rrset, ldns_rr_descriptor, ldns_rr_descript.

(yeah ldns_is_rrset shows up twice, iconic of her honestly, we're not touching it 😭)

And also: perldoc Net::DNS, RFC1034, RFC1035, RFC4033, RFC4034 and RFC4035.

🧚 REMARKS 🧚

This manpage was automatically generated from the ldns source code.

okay bestie that's the whole page!! this one's ldns(3) and it's dated 30 May 2006 — old enough to be vintage but the info still slaps. go forth and build something cute with it, ily, mwah 💖🌸✨

📦 where this page comes from