dns

type Answer struct {
	// ReceivedAt contains time when message is received.  If answer is
	// from local cache (host or zone file), its value is 0.
	ReceivedAt int64

	// AccessedAt contains time when message last accessed.  This field
	// is used to prune old answer from caches.
	AccessedAt int64

	// QName contains DNS question name, a copy of msg.Question.Name.
	QName string
	// qtype contains DNS question type, a copy of msg.Question.Type.
	QType uint16
	// qclass contains DNS question class, a copy of msg.Question.Class.
	QClass uint16
	// contains filtered or unexported fields
}

type Client interface {
	Close() error
	Lookup(allowRecursion bool, qtype, qclass uint16, qname string) (*Message, error)
	Query(req *Message) (*Message, error)
	RemoteAddr() string
	SetRemoteAddr(addr string) error
	SetTimeout(t time.Duration)
}

type DoHClient struct {
	// contains filtered or unexported fields
}

type DoTClient struct {
	// contains filtered or unexported fields
}

type HostsFile struct {
	Path    string `json:"-"`
	Name    string
	Records []*ResourceRecord `json:"-"`
	// contains filtered or unexported fields
}

type Message struct {
	Header     SectionHeader
	Question   SectionQuestion
	Answer     []ResourceRecord
	Authority  []ResourceRecord
	Additional []ResourceRecord
	// contains filtered or unexported fields
}

type OpCode byte

type RDataHINFO struct {
	CPU []byte
	OS  []byte
}

type RDataMINFO struct {
	// A <domain-name> which specifies a mailbox which is responsible for
	// the mailing list or mailbox.  If this domain name names the root,
	// the owner of the MINFO RR is responsible for itself.  Note that
	// many existing mailing lists use a mailbox X-request for the RMAILBX
	// field of mailing list X, e.g., Msgroup-request for Msgroup.  This
	// field provides a more general mechanism.
	RMailBox string

	// A <domain-name> which specifies a mailbox which is to receive error
	// messages related to the mailing list or mailbox specified by the
	// owner of the MINFO RR (similar to the ERRORS-TO: field which has
	// been proposed).  If this domain name names the root, errors should
	// be returned to the sender of the message.
	EmailBox string
}

type RDataMX struct {
	// A 16 bit integer which specifies the preference given to this RR
	// among others at the same owner.  Lower values are preferred.
	Preference int16

	// A <domain-name> which specifies a host willing to act as a mail
	// exchange for the owner name.
	Exchange string
}

type RDataOPT struct {
	// Forms the upper 8 bits of extended 12-bit RCODE (together with the
	// 4 bits defined in [RFC1035].  Note that EXTENDED-RCODE value 0
	// indicates that an unextended RCODE is in use (values 0 through 15).
	ExtRCode byte

	// Indicates the implementation level of the setter.  Full conformance
	// with this specification is indicated by version '0'.  Requestors
	// are encouraged to set this to the lowest implemented level capable
	// of expressing a transaction, to minimise the responder and network
	// load of discovering the greatest common implementation level
	// between requestor and responder.  A requestor's version numbering
	// strategy MAY ideally be a run-time configuration option.
	Version byte

	// DNSSEC OK bit as defined by [RFC3225].
	DO bool

	// Assigned by the Expert Review process as defined by the DNSEXT
	// working group and the IESG.
	Code uint16

	// Size (in octets) of OPTION-DATA.
	Length uint16

	// Varies per OPTION-CODE.  MUST be treated as a bit field.
	Data []byte
}

type RDataSOA struct {
	// The <domain-name> of the name server that was the original or
	// primary source of data for this zone.
	MName string

	// A <domain-name> which specifies the mailbox of the person
	// responsible for this zone.
	RName string

	// The unsigned 32 bit version number of the original copy of the
	// zone.  Zone transfers preserve this value.  This value wraps and
	// should be compared using sequence space arithmetic.
	Serial uint32

	// A 32 bit time interval before the zone should be refreshed.
	Refresh int32

	// A 32 bit time interval that should elapse before a failed refresh
	// should be retried.
	Retry int32

	// A 32 bit time value that specifies the upper limit on the time
	// interval that can elapse before the zone is no longer
	// authoritative.
	Expire int32

	// The unsigned 32 bit minimum TTL field that should be exported with
	// any RR from this zone.
	Minimum uint32
}

type RDataSRV struct {
	// The symbolic name of the desired service, as defined in Assigned
	// Numbers [STD 2] or locally.  An underscore (_) is prepended to
	// the service identifier to avoid collisions with DNS labels that
	// occur in nature.
	//
	// Some widely used services, notably POP, don't have a single
	// universal name.  If Assigned Numbers names the service
	// indicated, that name is the only name which is legal for SRV
	// lookups.  The Service is case insensitive.
	Service string

	// The symbolic name of the desired protocol, with an underscore
	// (_) prepended to prevent collisions with DNS labels that occur
	// in nature.  _TCP and _UDP are at present the most useful values
	// for this field, though any name defined by Assigned Numbers or
	// locally may be used (as for Service).  The Proto is case
	// insensitive.
	Proto string

	// The domain this RR refers to.  The SRV RR is unique in that the
	// name one searches for is not this name; the example near the end
	// shows this clearly.
	Name string

	// The priority of this target host.  A client MUST attempt to
	// contact the target host with the lowest-numbered priority it can
	// reach; target hosts with the same priority SHOULD be tried in an
	// order defined by the weight field.  The range is 0-65535.  This
	// is a 16 bit unsigned integer in network byte order.
	Priority uint16

	// A server selection mechanism.  The weight field specifies a
	// relative weight for entries with the same priority. Larger
	// weights SHOULD be given a proportionately higher probability of
	// being selected. The range of this number is 0-65535.  This is a
	// 16 bit unsigned integer in network byte order.  Domain
	// administrators SHOULD use Weight 0 when there isn't any server
	// selection to do, to make the RR easier to read for humans (less
	// noisy).  In the presence of records containing weights greater
	// than 0, records with weight 0 should have a very small chance of
	// being selected.
	//
	// In the absence of a protocol whose specification calls for the
	// use of other weighting information, a client arranges the SRV
	// RRs of the same Priority in the order in which target hosts,
	// specified by the SRV RRs, will be contacted. The following
	// algorithm SHOULD be used to order the SRV RRs of the same
	// priority:
	//
	// To select a target to be contacted next, arrange all SRV RRs
	// (that have not been ordered yet) in any order, except that all
	// those with weight 0 are placed at the beginning of the list.
	//
	// Compute the sum of the weights of those RRs, and with each RR
	// associate the running sum in the selected order. Then choose a
	// uniform random number between 0 and the sum computed
	// (inclusive), and select the RR whose running sum value is the
	// first in the selected order which is greater than or equal to
	// the random number selected. The target host specified in the
	// selected SRV RR is the next one to be contacted by the client.
	// Remove this SRV RR from the set of the unordered SRV RRs and
	// apply the described algorithm to the unordered SRV RRs to select
	// the next target host.  Continue the ordering process until there
	// are no unordered SRV RRs.  This process is repeated for each
	// Priority.
	Weight uint16

	// The port on this target host of this service.  The range is 0-
	// 65535.  This is a 16 bit unsigned integer in network byte order.
	// This is often as specified in Assigned Numbers but need not be.
	Port uint16

	// The domain name of the target host.  There MUST be one or more
	// address records for this name, the name MUST NOT be an alias (in
	// the sense of RFC 1034 or RFC 2181).  Implementors are urged, but
	// not required, to return the address record(s) in the Additional
	// Data section.  Unless and until permitted by future standards
	// action, name compression is not to be used for this field.
	//
	// A Target of "." means that the service is decidedly not
	// available at this domain.
	Target string
}

type RDataWKS struct {
	Address  []byte
	Protocol byte
	BitMap   []byte
}

type ResourceRecord struct {
	// A domain name to which this resource record pertains.
	Name string

	// Two octets containing one of the RR type codes.  This field
	// specifies the meaning of the data in the RDATA field.
	Type uint16

	// Two octets which specify the class of the data in the RDATA field.
	Class uint16

	// A 32 bit unsigned integer that specifies the time interval (in
	// seconds) that the resource record may be cached before it should be
	// discarded.  Zero values are interpreted to mean that the RR can
	// only be used for the transaction in progress, and should not be
	// cached.
	TTL uint32

	// Value hold the generic value for all record types.
	Value interface{}
	// contains filtered or unexported fields
}

type ResponseCode byte

type SectionHeader struct {
	//
	// A 16 bit identifier assigned by the program that generates
	// any kind of query.  This identifier is copied the corresponding
	// reply and can be used by the requester to match up replies to
	// outstanding queries.
	//
	ID uint16

	//
	// A one bit field that specifies whether this message is a query (0),
	// or a response (1).
	//
	IsQuery bool

	//
	// A four bit field that specifies kind of query in this message.
	// This value is set by the originator of a query and copied into the
	// response.
	//
	Op OpCode

	//
	// Authoritative Answer - this bit is valid in responses, and
	// specifies that the responding name server is an authority for the
	// domain name in question section.  Note that the contents of the
	// answer section may have multiple owner names because of aliases.
	// The AA bit corresponds to the name which matches the query name, or
	// the first owner name in the answer section.
	//
	IsAA bool

	//
	// TrunCation - specifies that this message was truncated due to
	// length greater than that permitted on the transmission channel.
	//
	IsTC bool

	//
	// Recursion Desired - this bit may be set in a query and is copied
	// into the response.  If RD is set, it directs the name server to
	// pursue the query recursively.  Recursive query support is optional.
	//
	IsRD bool

	//
	// Recursion Available - this bit is set or cleared in a response, and
	// denotes whether recursive query support is available in the name
	// server.
	//
	IsRA bool

	//
	// Response code - this 4 bit field is set as part of responses.
	//
	RCode ResponseCode

	// An unsigned 16 bit integer specifying the number of entries in the
	// question section.
	QDCount uint16

	// An unsigned 16 bit integer specifying the number of resource
	// records in the answer section.
	ANCount uint16

	// An unsigned 16 bit integer specifying the number of name server
	// resource records in the authority records section.
	NSCount uint16

	// An unsigned 16 bit integer specifying the number of resource
	// records in the additional records section.
	ARCount uint16
}

type SectionQuestion struct {
	// A domain name represented as a sequence of labels, where each label
	// consists of a length octet followed by that number of octets.  The
	// domain name terminates with the zero length octet for the null
	// label of the root.  Note that this field may be an odd number of
	// octets; no padding is used.
	Name string

	// A two octet code which specifies the type of the query.  The values
	// for this field include all codes valid for a TYPE field, together
	// with some more general codes which can match more than one type of
	// RR.
	Type uint16

	// A two octet code that specifies the class of the query.  For
	// example, the QCLASS field is IN for the Internet.
	Class uint16
}

type Server struct {
	HostsFiles map[string]*HostsFile
	// contains filtered or unexported fields
}

type ServerOptions struct {
	// ListenAddress ip address and port number to serve query.
	// This field is optional, default to "0.0.0.0:53".
	ListenAddress string `ini:"dns:server:listen"`

	// HTTPIdleTimeout number of seconds before considering the client of
	// HTTP connection to be closed.
	// This field is optional, default to 120 seconds.
	HTTPIdleTimeout time.Duration `ini:"dns:server:http.idle_timeout"`

	// HTTPPort port for listening DNS over HTTP (DoH), default to 0.
	// If its zero, the server will not serve DNS over HTTP.
	HTTPPort uint16 `ini:"dns:server:http.port"`

	// TLSPort port for listening DNS over TLS, default to 0.
	// If its zero, the server will not serve DNS over TLS.
	TLSPort uint16 `ini:"dns:server:tls.port"`

	//
	// NameServers contains list of parent name servers.
	//
	// Answer that does not exist on local will be forwarded to parent
	// name servers.  If this field is empty, any query that does not have
	// an answer in local caches, will be returned with response code
	// RCodeErrName (3).
	//
	// The name server use the URI format,
	//
	//	nameserver  = [ scheme "://" ] ( ip-address / domain-name ) [:port]
	//	scheme      = ( "udp" / "tcp" / "https" )
	//	ip-address  = ( ip4 / ip6 )
	//	domain-name = ; fully qualified domain name
	//
	// If no scheme is given, it will default to "udp".
	// The domain-name MUST only used if scheme is "https".
	//
	// Example,
	//
	//	udp://35.240.172.103
	//	tcp://35.240.172.103:5353
	//	https://35.240.172.103:853 (DNS over TLS)
	//	https://kilabit.info/dns-query (DNS over HTTPS)
	//
	NameServers []string `ini:"dns:server:parent"`

	//
	// FallbackNS contains list of parent name servers that will be
	// queried if the primary NameServers return an error.
	//
	// This field use the same format as NameServers.
	//
	FallbackNS []string

	// TLSCertFile contains path to certificate for serving DNS over TLS
	// and HTTPS.
	// This field is optional, if its empty, server will listening on
	// unsecure HTTP connection only.
	TLSCertFile string `ini:"dns:server:tls.certificate"`

	// TLSPrivateKey contains path to certificate private key file.
	TLSPrivateKey string `ini:"dns:server:tls.private_key"`

	// TLSAllowInsecure option to allow to serve DoH with self-signed
	// certificate.
	// This field is optional.
	TLSAllowInsecure bool `ini:"dns:server:tls.allow_insecure"`

	// DoHBehindProxy allow serving DNS over insecure HTTP, even if
	// certificate file is defined.
	// This option allow serving DNS request forwarded by another proxy
	// server.
	DoHBehindProxy bool `ini:"dns:server:doh.behind_proxy"`

	// PruneDelay define a delay where caches will be pruned.
	// This field is optional, minimum value is 1 minute, and default
	// value is 1 hour.
	// For example, if its set to 1 hour, every 1 hour the caches will be
	// inspected to remove answers that has not been accessed more than or
	// equal to PruneThreshold.
	PruneDelay time.Duration `ini:"dns:server:cache.prune_delay"`

	// PruneThreshold define negative duration where answers will be
	// pruned from caches.
	// This field is optional, minimum value is -1 minute, and default
	// value is -1 hour,
	// For example, if its set to -1 minute, any answers that has not been
	// accessed in the last 1 minute will be removed from cache.
	PruneThreshold time.Duration `ini:"dns:server:cache.prune_threshold"`
	// contains filtered or unexported fields
}

type TCPClient struct {
	// contains filtered or unexported fields
}

type UDPClient struct {
	sync.Mutex
	// contains filtered or unexported fields
}

type UDPClientPool struct {
	sync.Mutex
	// contains filtered or unexported fields
}

type ZoneFile struct {
	Path    string `json:"-"`
	Name    string
	SOA     ResourceRecord
	Records zoneRecords
	// contains filtered or unexported fields
}