chromium/third_party/openscreen/src/discovery/mdns/public/mdns_records.h

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef DISCOVERY_MDNS_PUBLIC_MDNS_RECORDS_H_
#define DISCOVERY_MDNS_PUBLIC_MDNS_RECORDS_H_

#include <algorithm>
#include <chrono>
#include <functional>
#include <initializer_list>
#include <ostream>
#include <string>
#include <string_view>
#include <utility>
#include <vector>

#include "absl/types/variant.h"
#include "discovery/mdns/public/mdns_constants.h"
#include "platform/base/error.h"
#include "platform/base/interface_info.h"
#include "platform/base/ip_address.h"
#include "util/osp_logging.h"
#include "util/string_util.h"

namespace openscreen::discovery {

bool IsValidDomainLabel(std::string_view label);

// Represents domain name as a collection of labels, ensures label length and
// domain name length requirements are met.
class DomainName { … };

// Parsed representation of the extra data in a record. Does not include
// standard DNS record data such as TTL, Name, Type, and Class. We use it to
// distinguish a raw record type that we do not know the identity of.
class RawRecordRdata { … };

// SRV record format (http://www.ietf.org/rfc/rfc2782.txt):
//   2 bytes network-order unsigned priority
//   2 bytes network-order unsigned weight
//   2 bytes network-order unsigned port
// target: domain name (on-the-wire representation)
class SrvRecordRdata { … };

// A Record format (http://www.ietf.org/rfc/rfc1035.txt):
// 4 bytes for IP address.
class ARecordRdata { … };

// AAAA Record format (http://www.ietf.org/rfc/rfc1035.txt):
// 16 bytes for IP address.
class AAAARecordRdata { … };

// PTR record format (http://www.ietf.org/rfc/rfc1035.txt):
// domain: On the wire representation of domain name.
class PtrRecordRdata { … };

// TXT record format (http://www.ietf.org/rfc/rfc1035.txt).
// texts: One or more <entries>.
// An <entry> is a length octet followed by as many data octets.
//
// DNS-SD interprets <entries> as a list of boolean keys and key=value
// attributes.  See https://tools.ietf.org/html/rfc6763#section-6 for details.
class TxtRecordRdata { … };

// NSEC record format (https://tools.ietf.org/html/rfc4034#section-4).
// In mDNS, this record type is used for representing negative responses to
// queries.
//
// next_domain_name: The next domain to process. In mDNS, this value is expected
// to match the record-level domain name in a negative response.
//
// An example of how the |types_| vector is serialized is as follows:
// When encoding the following DNS types:
// - A (value 1)
// - MX (value 15)
// - RRSIG (value 46)
// - NSEC (value 47)
// - TYPE1234 (value 1234)
// The result would be:
//          0x00 0x06 0x40 0x01 0x00 0x00 0x00 0x03
//          0x04 0x1b 0x00 0x00 0x00 0x00 0x00 0x00
//          0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
//          0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
//          0x00 0x00 0x00 0x00 0x20
class NsecRecordRdata { … };

// The OPT pseudo-record / meta-record as defined by RFC6891.
class OptRecordRdata { … };

Rdata;

// Resource record top level format (http://www.ietf.org/rfc/rfc1035.txt):
// name: the name of the node to which this resource record pertains.
// type: 2 bytes network-order RR TYPE code.
// class: 2 bytes network-order RR CLASS code.
// ttl: 4 bytes network-order cache time interval.
// rdata:  RDATA describing the resource.  The format of this information varies
// according to the TYPE and CLASS of the resource record.
class MdnsRecord { … };

// Creates an A or AAAA record as appropriate for the provided parameters.
MdnsRecord CreateAddressRecord(DomainName name, const IPAddress& address);

// Question top level format (http://www.ietf.org/rfc/rfc1035.txt):
// name: a domain name which identifies the target resource set.
// type: 2 bytes network-order RR TYPE code.
// class: 2 bytes network-order RR CLASS code.
class MdnsQuestion { … };

// Message top level format (http://www.ietf.org/rfc/rfc1035.txt):
// id: 2 bytes network-order identifier assigned by the program that generates
// any kind of query. This identifier is copied to the corresponding reply and
// can be used by the requester to match up replies to outstanding queries.
// flags: 2 bytes network-order flags bitfield.
// questions: questions in the message.
// answers: resource records that answer the questions.
// authority_records: resource records that point toward authoritative name.
// servers additional_records: additional resource records that relate to the
// query.
class MdnsMessage { … };

uint16_t CreateMessageId();

// Determines whether a record of the given type can be published.
bool CanBePublished(DnsType type);

// Determines whether a record of the given type can be queried for.
bool CanBeQueried(DnsType type);

// Determines whether a record of the given type received over the network
// should be processed.
bool CanBeProcessed(DnsType type);

}  // namespace openscreen::discovery

#endif  // DISCOVERY_MDNS_PUBLIC_MDNS_RECORDS_H_