[relay] Feature/relay integration (#2244)

This update adds new relay integration for NetBird clients. The new relay is based on web sockets and listens on a single port.

- Adds new relay implementation with websocket with single port relaying mechanism
- refactor peer connection logic, allowing upgrade and downgrade from/to P2P connection
- peer connections are faster since it connects first to relay and then upgrades to P2P
- maintains compatibility with old clients by not using the new relay
- updates infrastructure scripts with new relay service

client/internal/peer/handshaker.go

@@ -0,0 +1,192 @@
+package peer
+
+import (
+	"context"
+	"errors"
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/version"
+)
+
+var (
+	ErrSignalIsNotReady = errors.New("signal is not ready")
+)
+
+// IceCredentials ICE protocol credentials struct
+type IceCredentials struct {
+	UFrag string
+	Pwd   string
+}
+
+// OfferAnswer represents a session establishment offer or answer
+type OfferAnswer struct {
+	IceCredentials IceCredentials
+	// WgListenPort is a remote WireGuard listen port.
+	// This field is used when establishing a direct WireGuard connection without any proxy.
+	// We can set the remote peer's endpoint with this port.
+	WgListenPort int
+
+	// Version of NetBird Agent
+	Version string
+	// RosenpassPubKey is the Rosenpass public key of the remote peer when receiving this message
+	// This value is the local Rosenpass server public key when sending the message
+	RosenpassPubKey []byte
+	// RosenpassAddr is the Rosenpass server address (IP:port) of the remote peer when receiving this message
+	// This value is the local Rosenpass server address when sending the message
+	RosenpassAddr string
+
+	// relay server address
+	RelaySrvAddress string
+}
+
+type Handshaker struct {
+	mu                  sync.Mutex
+	ctx                 context.Context
+	log                 *log.Entry
+	config              ConnConfig
+	signaler            *Signaler
+	ice                 *WorkerICE
+	relay               *WorkerRelay
+	onNewOfferListeners []func(*OfferAnswer)
+
+	// remoteOffersCh is a channel used to wait for remote credentials to proceed with the connection
+	remoteOffersCh chan OfferAnswer
+	// remoteAnswerCh is a channel used to wait for remote credentials answer (confirmation of our offer) to proceed with the connection
+	remoteAnswerCh chan OfferAnswer
+}
+
+func NewHandshaker(ctx context.Context, log *log.Entry, config ConnConfig, signaler *Signaler, ice *WorkerICE, relay *WorkerRelay) *Handshaker {
+	return &Handshaker{
+		ctx:            ctx,
+		log:            log,
+		config:         config,
+		signaler:       signaler,
+		ice:            ice,
+		relay:          relay,
+		remoteOffersCh: make(chan OfferAnswer),
+		remoteAnswerCh: make(chan OfferAnswer),
+	}
+}
+
+func (h *Handshaker) AddOnNewOfferListener(offer func(remoteOfferAnswer *OfferAnswer)) {
+	h.onNewOfferListeners = append(h.onNewOfferListeners, offer)
+}
+
+func (h *Handshaker) Listen() {
+	for {
+		h.log.Debugf("wait for remote offer confirmation")
+		remoteOfferAnswer, err := h.waitForRemoteOfferConfirmation()
+		if err != nil {
+			var connectionClosedError *ConnectionClosedError
+			if errors.As(err, &connectionClosedError) {
+				h.log.Tracef("stop handshaker")
+				return
+			}
+			h.log.Errorf("failed to received remote offer confirmation: %s", err)
+			continue
+		}
+
+		h.log.Debugf("received connection confirmation, running version %s and with remote WireGuard listen port %d", remoteOfferAnswer.Version, remoteOfferAnswer.WgListenPort)
+		for _, listener := range h.onNewOfferListeners {
+			go listener(remoteOfferAnswer)
+		}
+	}
+}
+
+func (h *Handshaker) SendOffer() error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return h.sendOffer()
+}
+
+// OnRemoteOffer handles an offer from the remote peer and returns true if the message was accepted, false otherwise
+// doesn't block, discards the message if connection wasn't ready
+func (h *Handshaker) OnRemoteOffer(offer OfferAnswer) bool {
+	select {
+	case h.remoteOffersCh <- offer:
+		return true
+	default:
+		h.log.Debugf("OnRemoteOffer skipping message because is not ready")
+		// connection might not be ready yet to receive so we ignore the message
+		return false
+	}
+}
+
+// OnRemoteAnswer handles an offer from the remote peer and returns true if the message was accepted, false otherwise
+// doesn't block, discards the message if connection wasn't ready
+func (h *Handshaker) OnRemoteAnswer(answer OfferAnswer) bool {
+	select {
+	case h.remoteAnswerCh <- answer:
+		return true
+	default:
+		// connection might not be ready yet to receive so we ignore the message
+		h.log.Debugf("OnRemoteAnswer skipping message because is not ready")
+		return false
+	}
+}
+
+func (h *Handshaker) waitForRemoteOfferConfirmation() (*OfferAnswer, error) {
+	select {
+	case remoteOfferAnswer := <-h.remoteOffersCh:
+		// received confirmation from the remote peer -> ready to proceed
+		err := h.sendAnswer()
+		if err != nil {
+			return nil, err
+		}
+		return &remoteOfferAnswer, nil
+	case remoteOfferAnswer := <-h.remoteAnswerCh:
+		return &remoteOfferAnswer, nil
+	case <-h.ctx.Done():
+		// closed externally
+		return nil, NewConnectionClosedError(h.config.Key)
+	}
+}
+
+// sendOffer prepares local user credentials and signals them to the remote peer
+func (h *Handshaker) sendOffer() error {
+	if !h.signaler.Ready() {
+		return ErrSignalIsNotReady
+	}
+
+	iceUFrag, icePwd := h.ice.GetLocalUserCredentials()
+	offer := OfferAnswer{
+		IceCredentials:  IceCredentials{iceUFrag, icePwd},
+		WgListenPort:    h.config.LocalWgPort,
+		Version:         version.NetbirdVersion(),
+		RosenpassPubKey: h.config.RosenpassPubKey,
+		RosenpassAddr:   h.config.RosenpassAddr,
+	}
+
+	addr, err := h.relay.RelayInstanceAddress()
+	if err == nil {
+		offer.RelaySrvAddress = addr
+	}
+
+	return h.signaler.SignalOffer(offer, h.config.Key)
+}
+
+func (h *Handshaker) sendAnswer() error {
+	h.log.Debugf("sending answer")
+	uFrag, pwd := h.ice.GetLocalUserCredentials()
+
+	answer := OfferAnswer{
+		IceCredentials:  IceCredentials{uFrag, pwd},
+		WgListenPort:    h.config.LocalWgPort,
+		Version:         version.NetbirdVersion(),
+		RosenpassPubKey: h.config.RosenpassPubKey,
+		RosenpassAddr:   h.config.RosenpassAddr,
+	}
+	addr, err := h.relay.RelayInstanceAddress()
+	if err == nil {
+		answer.RelaySrvAddress = addr
+	}
+
+	err = h.signaler.SignalAnswer(answer, h.config.Key)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}