package holepunch

import (
	
	
	
	
	

	logging 
	
	
	
	
	
	
	

	ma 
)

const defaultDirectDialTimeout = 10 * time.Second

// Protocol is the libp2p protocol for Hole Punching.
const Protocol protocol.ID = "/libp2p/dcutr"

var log = logging.Logger("p2p-holepunch")

// StreamTimeout is the timeout for the hole punch protocol stream.
var StreamTimeout = 1 * time.Minute

const (
	ServiceName = "libp2p.holepunch"

	maxMsgSize = 4 * 1024 // 4K
)

// ErrClosed is returned when the hole punching is closed
var ErrClosed = errors.New("hole punching service closing")

type Option func(*Service) error

func ( time.Duration) Option {
	return func( *Service) error {
		.directDialTimeout = 
		return nil
	}
}

// The Service runs on every node that supports the DCUtR protocol.
type Service struct {
	ctx       context.Context
	ctxCancel context.CancelFunc

	host host.Host
	// ids helps with connection reversal. We wait for identify to complete and attempt
	// a direct connection to the peer if it's publicly reachable.
	ids identify.IDService
	// listenAddrs provides the addresses for the host to be used for hole punching. We use this
	// and not host.Addrs because host.Addrs might remove public unreachable address and only advertise
	// publicly reachable relay addresses.
	listenAddrs func() []ma.Multiaddr

	directDialTimeout time.Duration
	holePuncherMx     sync.Mutex
	holePuncher       *holePuncher

	hasPublicAddrsChan chan struct{}

	tracer *tracer
	filter AddrFilter

	refCount sync.WaitGroup

	// Prior to https://github.com/libp2p/go-libp2p/pull/3044, go-libp2p would
	// pick the opposite roles for client/server a hole punch. Setting this to
	// true preserves that behavior
	legacyBehavior bool
}

// SetLegacyBehavior is only exposed for testing purposes.
// Do not set this unless you know what you are doing.
func ( *Service) ( bool) {
	.legacyBehavior = 
}

// NewService creates a new service that can be used for hole punching
// The Service runs on all hosts that support the DCUtR protocol,
// no matter if they are behind a NAT / firewall or not.
// The Service handles DCUtR streams (which are initiated from the node behind
// a NAT / Firewall once we establish a connection to them through a relay.
//
// listenAddrs MUST only return public addresses.
func ( host.Host,  identify.IDService,  func() []ma.Multiaddr,  ...Option) (*Service, error) {
	if  == nil {
		return nil, errors.New("identify service can't be nil")
	}

	,  := context.WithCancel(context.Background())
	 := &Service{
		ctx:                ,
		ctxCancel:          ,
		host:               ,
		ids:                ,
		listenAddrs:        ,
		hasPublicAddrsChan: make(chan struct{}),
		directDialTimeout:  defaultDirectDialTimeout,
		legacyBehavior:     true,
	}

	for ,  := range  {
		if  := ();  != nil {
			()
			return nil, 
		}
	}
	.tracer.Start()

	.refCount.Add(1)
	go .waitForPublicAddr()

	return , nil
}

func ( *Service) () {
	defer .refCount.Done()

	log.Debugw("waiting until we have at least one public address", "peer", .host.ID())

	// TODO: We should have an event here that fires when identify discovers a new
	// address.
	// As we currently don't have an event like this, just check our observed addresses
	// regularly (exponential backoff starting at 250 ms, capped at 5s).
	 := 250 * time.Millisecond
	const  = 5 * time.Second
	 := time.NewTimer()
	defer .Stop()
	for {
		if len(.listenAddrs()) > 0 {
			log.Debugf("Host %s now has a public address (%s). Starting holepunch protocol.", .host.ID(), .host.Addrs())
			.host.SetStreamHandler(Protocol, .handleNewStream)
			break
		}

		select {
		case <-.ctx.Done():
			return
		case <-.C:
			 *= 2
			if  >  {
				 = 
			}
			.Reset()
		}
	}

	.holePuncherMx.Lock()
	if .ctx.Err() != nil {
		// service is closed
		return
	}
	.holePuncher = newHolePuncher(.host, .ids, .listenAddrs, .tracer, .filter)
	.holePuncher.directDialTimeout = .directDialTimeout
	.holePuncher.legacyBehavior = .legacyBehavior
	.holePuncherMx.Unlock()
	close(.hasPublicAddrsChan)
}

// Close closes the Hole Punch Service.
func ( *Service) () error {
	var  error
	.ctxCancel()
	.holePuncherMx.Lock()
	if .holePuncher != nil {
		 = .holePuncher.Close()
	}
	.holePuncherMx.Unlock()
	.tracer.Close()
	.host.RemoveStreamHandler(Protocol)
	.refCount.Wait()
	return 
}

func ( *Service) ( network.Stream) ( time.Duration,  []ma.Multiaddr,  []ma.Multiaddr,  error) {
	// sanity check: a hole punch request should only come from peers behind a relay
	if !isRelayAddress(.Conn().RemoteMultiaddr()) {
		return 0, nil, nil, fmt.Errorf("received hole punch stream: %s", .Conn().RemoteMultiaddr())
	}
	 = .listenAddrs()
	if .filter != nil {
		 = .filter.FilterLocal(.Conn().RemotePeer(), )
	}

	// If we can't tell the peer where to dial us, there's no point in starting the hole punching.
	if len() == 0 {
		return 0, nil, nil, errors.New("rejecting hole punch request, as we don't have any public addresses")
	}

	if  := .Scope().ReserveMemory(maxMsgSize, network.ReservationPriorityAlways);  != nil {
		log.Debugf("error reserving memory for stream: %s", )
		return 0, nil, nil, 
	}
	defer .Scope().ReleaseMemory(maxMsgSize)

	 := pbio.NewDelimitedWriter()
	 := pbio.NewDelimitedReader(, maxMsgSize)

	// Read Connect message
	 := new(pb.HolePunch)

	.SetDeadline(time.Now().Add(StreamTimeout))

	if  := .ReadMsg();  != nil {
		return 0, nil, nil, fmt.Errorf("failed to read message from initiator: %w", )
	}
	if  := .GetType();  != pb.HolePunch_CONNECT {
		return 0, nil, nil, fmt.Errorf("expected CONNECT message from initiator but got %d", )
	}

	 := removeRelayAddrs(addrsFromBytes(.ObsAddrs))
	if .filter != nil {
		 = .filter.FilterRemote(.Conn().RemotePeer(), )
	}

	log.Debugw("received hole punch request", "peer", .Conn().RemotePeer(), "addrs", )
	if len() == 0 {
		return 0, nil, nil, errors.New("expected CONNECT message to contain at least one address")
	}

	// Write CONNECT message
	.Reset()
	.Type = pb.HolePunch_CONNECT.Enum()
	.ObsAddrs = addrsToBytes()
	 := time.Now()
	if  := .WriteMsg();  != nil {
		return 0, nil, nil, fmt.Errorf("failed to write CONNECT message to initiator: %w", )
	}

	// Read SYNC message
	.Reset()
	if  := .ReadMsg();  != nil {
		return 0, nil, nil, fmt.Errorf("failed to read message from initiator: %w", )
	}
	if  := .GetType();  != pb.HolePunch_SYNC {
		return 0, nil, nil, fmt.Errorf("expected SYNC message from initiator but got %d", )
	}
	return time.Since(), , , nil
}

func ( *Service) ( network.Stream) {
	// Check directionality of the underlying connection.
	// Peer A receives an inbound connection from peer B.
	// Peer A opens a new hole punch stream to peer B.
	// Peer B receives this stream, calling this function.
	// Peer B sees the underlying connection as an outbound connection.
	if .Conn().Stat().Direction == network.DirInbound {
		.Reset()
		return
	}

	if  := .Scope().SetService(ServiceName);  != nil {
		log.Debugf("error attaching stream to holepunch service: %s", )
		.Reset()
		return
	}

	 := .Conn().RemotePeer()
	, , ,  := .incomingHolePunch()
	if  != nil {
		.tracer.ProtocolError(, )
		log.Debugw("error handling holepunching stream from", "peer", , "error", )
		.Reset()
		return
	}
	.Close()

	// Hole punch now by forcing a connect
	 := peer.AddrInfo{
		ID:    ,
		Addrs: ,
	}
	.tracer.StartHolePunch(, , )
	log.Debugw("starting hole punch", "peer", )
	 := time.Now()
	.tracer.HolePunchAttempt(.ID)
	,  := context.WithTimeout(.ctx, .directDialTimeout)
	 := false
	if .legacyBehavior {
		 = true
	}
	 = holePunchConnect(, .host, , )
	()
	 := time.Since()
	.tracer.EndHolePunch(, , )
	.tracer.HolePunchFinished("receiver", 1, , , getDirectConnection(.host, ))
}

// DirectConnect is only exposed for testing purposes.
// TODO: find a solution for this.
func ( *Service) ( peer.ID) error {
	<-.hasPublicAddrsChan
	.holePuncherMx.Lock()
	 := .holePuncher
	.holePuncherMx.Unlock()
	return .DirectConnect()
}