[client] Fix Rosenpass permissive mode handling (#3689)

fixes the Rosenpass preshared key handling to enable successful WireGuard handshakes when one side is in permissive mode. Key changes include:

Updating field accesses from RosenpassPubKey/RosenpassAddr to RosenpassConfig.PubKey/RosenpassConfig.Addr.
Modifying the preshared key computation logic to account for permissive mode.
Revising peer configuration in the Engine to use the new RosenpassConfig struct.

client/internal/engine.go

@@ -1231,36 +1231,19 @@ func (e *Engine) createPeerConn(pubKey string, allowedIPs []netip.Prefix) (*peer
 		PreSharedKey: e.config.PreSharedKey,
 	}
 
-	if e.config.RosenpassEnabled && !e.config.RosenpassPermissive {
-		lk := []byte(e.config.WgPrivateKey.PublicKey().String())
-		rk := []byte(wgConfig.RemoteKey)
-		var keyInput []byte
-		if string(lk) > string(rk) {
-			//nolint:gocritic
-			keyInput = append(lk[:16], rk[:16]...)
-		} else {
-			//nolint:gocritic
-			keyInput = append(rk[:16], lk[:16]...)
-		}
-
-		key, err := wgtypes.NewKey(keyInput)
-		if err != nil {
-			return nil, err
-		}
-
-		wgConfig.PreSharedKey = &key
-	}
-
 	// randomize connection timeout
 	timeout := time.Duration(rand.Intn(PeerConnectionTimeoutMax-PeerConnectionTimeoutMin)+PeerConnectionTimeoutMin) * time.Millisecond
 	config := peer.ConnConfig{
-		Key:             pubKey,
+		Key:         pubKey,
-		LocalKey:        e.config.WgPrivateKey.PublicKey().String(),
+		LocalKey:    e.config.WgPrivateKey.PublicKey().String(),
-		Timeout:         timeout,
+		Timeout:     timeout,
-		WgConfig:        wgConfig,
+		WgConfig:    wgConfig,
-		LocalWgPort:     e.config.WgPort,
+		LocalWgPort: e.config.WgPort,
-		RosenpassPubKey: e.getRosenpassPubKey(),
+		RosenpassConfig: peer.RosenpassConfig{
-		RosenpassAddr:   e.getRosenpassAddr(),
+			PubKey:         e.getRosenpassPubKey(),
+			Addr:           e.getRosenpassAddr(),
+			PermissiveMode: e.config.RosenpassPermissive,
+		},
 		ICEConfig: icemaker.Config{
 			StunTurn:             &e.stunTurn,
 			InterfaceBlackList:   e.config.IFaceBlackList,

client/internal/peer/conn.go

@@ -60,6 +60,15 @@ type WgConfig struct {
 	PreSharedKey *wgtypes.Key
 }
 
+type RosenpassConfig struct {
+	// RosenpassPubKey is this peer's Rosenpass public key
+	PubKey []byte
+	// RosenpassPubKey is this peer's RosenpassAddr server address (IP:port)
+	Addr string
+
+	PermissiveMode bool
+}
+
 // ConnConfig is a peer Connection configuration
 type ConnConfig struct {
 	// Key is a public key of a remote peer
@@ -73,10 +82,7 @@ type ConnConfig struct {
 
 	LocalWgPort int
 
-	// RosenpassPubKey is this peer's Rosenpass public key
+	RosenpassConfig RosenpassConfig
-	RosenpassPubKey []byte
-	// RosenpassPubKey is this peer's RosenpassAddr server address (IP:port)
-	RosenpassAddr string
 
 	// ICEConfig ICE protocol configuration
 	ICEConfig icemaker.Config
@@ -109,6 +115,8 @@ type Conn struct {
 	connIDICE            nbnet.ConnectionID
 	beforeAddPeerHooks   []nbnet.AddHookFunc
 	afterRemovePeerHooks []nbnet.RemoveHookFunc
+	// used to store the remote Rosenpass key for Relayed connection in case of connection update from ice
+	rosenpassRemoteKey []byte
 
 	wgProxyICE   wgproxy.Proxy
 	wgProxyRelay wgproxy.Proxy
@@ -375,7 +383,7 @@ func (conn *Conn) onICEConnectionIsReady(priority ConnPriority, iceConnInfo ICEC
 		wgProxy.Work()
 	}
 
-	if err = conn.configureWGEndpoint(ep); err != nil {
+	if err = conn.configureWGEndpoint(ep, iceConnInfo.RosenpassPubKey); err != nil {
 		conn.handleConfigurationFailure(err, wgProxy)
 		return
 	}
@@ -408,7 +416,7 @@ func (conn *Conn) onICEStateDisconnected() {
 		conn.dumpState.SwitchToRelay()
 		conn.wgProxyRelay.Work()
 
-		if err := conn.configureWGEndpoint(conn.wgProxyRelay.EndpointAddr()); err != nil {
+		if err := conn.configureWGEndpoint(conn.wgProxyRelay.EndpointAddr(), conn.rosenpassRemoteKey); err != nil {
 			conn.log.Errorf("failed to switch to relay conn: %v", err)
 		}
 
@@ -478,7 +486,7 @@ func (conn *Conn) onRelayConnectionIsReady(rci RelayConnInfo) {
 	}
 
 	wgProxy.Work()
-	if err := conn.configureWGEndpoint(wgProxy.EndpointAddr()); err != nil {
+	if err := conn.configureWGEndpoint(wgProxy.EndpointAddr(), rci.rosenpassPubKey); err != nil {
 		if err := wgProxy.CloseConn(); err != nil {
 			conn.log.Warnf("Failed to close relay connection: %v", err)
 		}
@@ -493,6 +501,7 @@ func (conn *Conn) onRelayConnectionIsReady(rci RelayConnInfo) {
 	}()
 
 	wgConfigWorkaround()
+	conn.rosenpassRemoteKey = rci.rosenpassPubKey
 	conn.currentConnPriority = connPriorityRelay
 	conn.statusRelay.Set(StatusConnected)
 	conn.setRelayedProxy(wgProxy)
@@ -556,13 +565,14 @@ func (conn *Conn) listenGuardEvent(ctx context.Context) {
 	}
 }
 
-func (conn *Conn) configureWGEndpoint(addr *net.UDPAddr) error {
+func (conn *Conn) configureWGEndpoint(addr *net.UDPAddr, remoteRPKey []byte) error {
+	presharedKey := conn.presharedKey(remoteRPKey)
 	return conn.config.WgConfig.WgInterface.UpdatePeer(
 		conn.config.WgConfig.RemoteKey,
 		conn.config.WgConfig.AllowedIps,
 		defaultWgKeepAlive,
 		addr,
-		conn.config.WgConfig.PreSharedKey,
+		presharedKey,
 	)
 }
 
@@ -783,6 +793,44 @@ func (conn *Conn) AllowedIP() netip.Addr {
 	return conn.config.WgConfig.AllowedIps[0].Addr()
 }
 
+func (conn *Conn) presharedKey(remoteRosenpassKey []byte) *wgtypes.Key {
+	if conn.config.RosenpassConfig.PubKey == nil {
+		return conn.config.WgConfig.PreSharedKey
+	}
+
+	if remoteRosenpassKey == nil && conn.config.RosenpassConfig.PermissiveMode {
+		return conn.config.WgConfig.PreSharedKey
+	}
+
+	determKey, err := conn.rosenpassDetermKey()
+	if err != nil {
+		conn.log.Errorf("failed to generate Rosenpass initial key: %v", err)
+		return conn.config.WgConfig.PreSharedKey
+	}
+
+	return determKey
+}
+
+// todo: move this logic into Rosenpass package
+func (conn *Conn) rosenpassDetermKey() (*wgtypes.Key, error) {
+	lk := []byte(conn.config.LocalKey)
+	rk := []byte(conn.config.Key) // remote key
+	var keyInput []byte
+	if string(lk) > string(rk) {
+		//nolint:gocritic
+		keyInput = append(lk[:16], rk[:16]...)
+	} else {
+		//nolint:gocritic
+		keyInput = append(rk[:16], lk[:16]...)
+	}
+
+	key, err := wgtypes.NewKey(keyInput)
+	if err != nil {
+		return nil, err
+	}
+	return &key, nil
+}
+
 func isController(config ConnConfig) bool {
 	return config.LocalKey > config.Key
 }

client/internal/peer/conn_test.go

@@ -2,6 +2,7 @@ package peer
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"sync"
 	"testing"
@@ -161,3 +162,145 @@ func TestConn_Status(t *testing.T) {
 		})
 	}
 }
+
+func TestConn_presharedKey(t *testing.T) {
+	conn1 := Conn{
+		config: ConnConfig{
+			Key:             "LLHf3Ma6z6mdLbriAJbqhX7+nM/B71lgw2+91q3LfhU=",
+			LocalKey:        "RRHf3Ma6z6mdLbriAJbqhX7+nM/B71lgw2+91q3LfhU=",
+			RosenpassConfig: RosenpassConfig{},
+		},
+	}
+	conn2 := Conn{
+		config: ConnConfig{
+			Key:             "RRHf3Ma6z6mdLbriAJbqhX7+nM/B71lgw2+91q3LfhU=",
+			LocalKey:        "LLHf3Ma6z6mdLbriAJbqhX7+nM/B71lgw2+91q3LfhU=",
+			RosenpassConfig: RosenpassConfig{},
+		},
+	}
+
+	tests := []struct {
+		conn1Permissive         bool
+		conn1RosenpassEnabled   bool
+		conn2Permissive         bool
+		conn2RosenpassEnabled   bool
+		conn1ExpectedInitialKey bool
+		conn2ExpectedInitialKey bool
+	}{
+		{
+			conn1Permissive:         false,
+			conn1RosenpassEnabled:   false,
+			conn2Permissive:         false,
+			conn2RosenpassEnabled:   false,
+			conn1ExpectedInitialKey: false,
+			conn2ExpectedInitialKey: false,
+		},
+		{
+			conn1Permissive:         false,
+			conn1RosenpassEnabled:   true,
+			conn2Permissive:         false,
+			conn2RosenpassEnabled:   true,
+			conn1ExpectedInitialKey: true,
+			conn2ExpectedInitialKey: true,
+		},
+		{
+			conn1Permissive:         false,
+			conn1RosenpassEnabled:   true,
+			conn2Permissive:         false,
+			conn2RosenpassEnabled:   false,
+			conn1ExpectedInitialKey: true,
+			conn2ExpectedInitialKey: false,
+		},
+		{
+			conn1Permissive:         false,
+			conn1RosenpassEnabled:   false,
+			conn2Permissive:         false,
+			conn2RosenpassEnabled:   true,
+			conn1ExpectedInitialKey: false,
+			conn2ExpectedInitialKey: true,
+		},
+		{
+			conn1Permissive:         true,
+			conn1RosenpassEnabled:   true,
+			conn2Permissive:         false,
+			conn2RosenpassEnabled:   false,
+			conn1ExpectedInitialKey: false,
+			conn2ExpectedInitialKey: false,
+		},
+		{
+			conn1Permissive:         false,
+			conn1RosenpassEnabled:   false,
+			conn2Permissive:         true,
+			conn2RosenpassEnabled:   true,
+			conn1ExpectedInitialKey: false,
+			conn2ExpectedInitialKey: false,
+		},
+		{
+			conn1Permissive:         true,
+			conn1RosenpassEnabled:   true,
+			conn2Permissive:         true,
+			conn2RosenpassEnabled:   true,
+			conn1ExpectedInitialKey: true,
+			conn2ExpectedInitialKey: true,
+		},
+		{
+			conn1Permissive:         false,
+			conn1RosenpassEnabled:   false,
+			conn2Permissive:         false,
+			conn2RosenpassEnabled:   true,
+			conn1ExpectedInitialKey: false,
+			conn2ExpectedInitialKey: true,
+		},
+		{
+			conn1Permissive:         false,
+			conn1RosenpassEnabled:   true,
+			conn2Permissive:         true,
+			conn2RosenpassEnabled:   true,
+			conn1ExpectedInitialKey: true,
+			conn2ExpectedInitialKey: true,
+		},
+	}
+
+	conn1.config.RosenpassConfig.PermissiveMode = true
+	for i, test := range tests {
+		tcase := i + 1
+		t.Run(fmt.Sprintf("Rosenpass test case %d", tcase), func(t *testing.T) {
+			conn1.config.RosenpassConfig = RosenpassConfig{}
+			conn2.config.RosenpassConfig = RosenpassConfig{}
+
+			if test.conn1RosenpassEnabled {
+				conn1.config.RosenpassConfig.PubKey = []byte("dummykey")
+			}
+			conn1.config.RosenpassConfig.PermissiveMode = test.conn1Permissive
+
+			if test.conn2RosenpassEnabled {
+				conn2.config.RosenpassConfig.PubKey = []byte("dummykey")
+			}
+			conn2.config.RosenpassConfig.PermissiveMode = test.conn2Permissive
+
+			conn1PresharedKey := conn1.presharedKey(conn2.config.RosenpassConfig.PubKey)
+			conn2PresharedKey := conn2.presharedKey(conn1.config.RosenpassConfig.PubKey)
+
+			if test.conn1ExpectedInitialKey {
+				if conn1PresharedKey == nil {
+					t.Errorf("Case %d: Expected conn1 to have a non-nil key, but got nil", tcase)
+				}
+			} else {
+				if conn1PresharedKey != nil {
+					t.Errorf("Case %d: Expected conn1 to have a nil key, but got %v", tcase, conn1PresharedKey)
+				}
+			}
+
+			// Assert conn2's key expectation
+			if test.conn2ExpectedInitialKey {
+				if conn2PresharedKey == nil {
+					t.Errorf("Case %d: Expected conn2 to have a non-nil key, but got nil", tcase)
+				}
+			} else {
+				if conn2PresharedKey != nil {
+					t.Errorf("Case %d: Expected conn2 to have a nil key, but got %v", tcase, conn2PresharedKey)
+				}
+			}
+		})
+	}
+}

client/internal/peer/handshaker.go

@@ -154,8 +154,8 @@ func (h *Handshaker) sendOffer() error {
 		IceCredentials:  IceCredentials{iceUFrag, icePwd},
 		WgListenPort:    h.config.LocalWgPort,
 		Version:         version.NetbirdVersion(),
-		RosenpassPubKey: h.config.RosenpassPubKey,
+		RosenpassPubKey: h.config.RosenpassConfig.PubKey,
-		RosenpassAddr:   h.config.RosenpassAddr,
+		RosenpassAddr:   h.config.RosenpassConfig.Addr,
 	}
 
 	addr, err := h.relay.RelayInstanceAddress()
@@ -174,8 +174,8 @@ func (h *Handshaker) sendAnswer() error {
 		IceCredentials:  IceCredentials{uFrag, pwd},
 		WgListenPort:    h.config.LocalWgPort,
 		Version:         version.NetbirdVersion(),
-		RosenpassPubKey: h.config.RosenpassPubKey,
+		RosenpassPubKey: h.config.RosenpassConfig.PubKey,
-		RosenpassAddr:   h.config.RosenpassAddr,
+		RosenpassAddr:   h.config.RosenpassConfig.Addr,
 	}
 	addr, err := h.relay.RelayInstanceAddress()
 	if err == nil {