Added support for changing the nickname at the "preLogin" stage

pkg/edition/java/proxy/events.go

@@ -1,8 +1,7 @@
 package proxy
 
 import (
-	"net"
-
+	"errors"
 	"go.minekube.com/brigodier"
 	"go.minekube.com/common/minecraft/component"
 	"go.minekube.com/gate/pkg/command"
@@ -14,6 +13,7 @@ import (
 	"go.minekube.com/gate/pkg/edition/java/proxy/message"
 	"go.minekube.com/gate/pkg/edition/java/proxy/player"
 	"go.minekube.com/gate/pkg/util/permission"
+	"net"
 )
 
 // PingEvent is fired when a request for server information is sent by a remote client,
@@ -115,11 +115,13 @@ func NewGameProfileRequestEvent(
 	inbound Inbound,
 	original profile.GameProfile,
 	onlineMode bool,
+	use profile.GameProfile,
 ) *GameProfileRequestEvent {
 	return &GameProfileRequestEvent{
 		inbound:    inbound,
 		original:   original,
 		onlineMode: onlineMode,
+		use:        use,
 	}
 }
 
@@ -138,20 +140,17 @@ func (e *GameProfileRequestEvent) OnlineMode() bool {
 	return e.onlineMode
 }
 
+// GameProfile returns the game originalProfile that will be used to initialize the connection with.
+// Should no originalProfile be set, the original originalProfile (given by the proxy) will be used.
+func (e *GameProfileRequestEvent) GameProfile() profile.GameProfile {
+	return e.use
+}
+
 // SetGameProfile sets the profile to use for this connection.
 func (e *GameProfileRequestEvent) SetGameProfile(p profile.GameProfile) {
 	e.use = p
 }
 
-// GameProfile returns the game profile that will be used to initialize the connection with.
-// Should no profile be set, the original profile (given by the proxy) will be used.
-func (e *GameProfileRequestEvent) GameProfile() profile.GameProfile {
-	if len(e.use.Name) == 0 {
-		return e.original
-	}
-	return e.use
-}
-
 //
 //
 //
@@ -228,18 +227,20 @@ func (p *PermissionsSetupEvent) SetFunc(fn permission.Func) {
 // but before the proxy authenticates the player with Mojang or before the player's proxy connection
 // is fully established (for offline mode).
 type PreLoginEvent struct {
-	connection Inbound
-	username   string
+	connection       Inbound
+	originalUsername string
 
-	result PreLoginResult
-	reason component.Component
+	result      PreLoginResult
+	useUsername string
+	reason      component.Component
 }
 
-func newPreLoginEvent(conn Inbound, username string) *PreLoginEvent {
+func newPreLoginEvent(conn Inbound, originalUsername string) *PreLoginEvent {
 	return &PreLoginEvent{
-		connection: conn,
-		username:   username,
-		result:     AllowedPreLogin,
+		connection:       conn,
+		originalUsername: originalUsername,
+		useUsername:      originalUsername,
+		result:           AllowedPreLogin,
 	}
 }
 
@@ -254,9 +255,23 @@ const (
 	ForceOfflineModePreLogin
 )
 
+// OriginalUsername returns the original username of the player.
+func (e *PreLoginEvent) OriginalUsername() string {
+	return e.originalUsername
+}
+
 // Username returns the username of the player.
 func (e *PreLoginEvent) Username() string {
-	return e.username
+	return e.useUsername
+}
+
+// SetUsername sets server username for the player.
+func (e *PreLoginEvent) SetUsername(username string) error {
+	if !playerNameRegex.MatchString(username) {
+		return errors.New("username must matches ^[A-Za-z0-9_]{2,16}$")
+	}
+	e.useUsername = username
+	return nil
 }
 
 // Conn returns the inbound connection that is connecting to the proxy.

pkg/edition/java/proxy/session_auth.go

@@ -18,10 +18,11 @@ import (
 type authSessionHandler struct {
 	*sessionHandlerDeps
 
-	log        logr.Logger
-	inbound    *loginInboundConn
-	profile    *profile.GameProfile
-	onlineMode bool
+	log             logr.Logger
+	inbound         *loginInboundConn
+	originalProfile *profile.GameProfile
+	useProfile      *profile.GameProfile
+	onlineMode      bool
 
 	connectedPlayer *connectedPlayer
 }
@@ -34,15 +35,17 @@ type playerRegistrar interface {
 
 func newAuthSessionHandler(
 	inbound *loginInboundConn,
-	profile *profile.GameProfile,
+	originalProfile *profile.GameProfile,
+	useProfile *profile.GameProfile,
 	onlineMode bool,
 	sessionHandlerDeps *sessionHandlerDeps,
 ) netmc.SessionHandler {
 	return &authSessionHandler{
 		sessionHandlerDeps: sessionHandlerDeps,
 		log:                logr.FromContextOrDiscard(inbound.Context()).WithName("authSession"),
 		inbound:            inbound,
-		profile:            profile,
+		originalProfile:    originalProfile,
+		useProfile:         useProfile,
 		onlineMode:         onlineMode,
 	}
 }
@@ -55,22 +58,24 @@ func (a *authSessionHandler) Disconnected() {
 }
 
 func (a *authSessionHandler) Activated() {
-	// Some connection types may need to alter the game profile.
-	gameProfile := *a.inbound.delegate.Type().AddGameProfileTokensIfRequired(
-		a.profile, a.config().Forwarding.Mode)
+	// Some connection types may need to alter the game originalProfile.
+	originalGameProfile := *a.inbound.delegate.Type().AddGameProfileTokensIfRequired(
+		a.originalProfile, a.config().Forwarding.Mode)
+	useGameProfile := *a.inbound.delegate.Type().AddGameProfileTokensIfRequired(
+		a.useProfile, a.config().Forwarding.Mode)
 
-	profileRequest := NewGameProfileRequestEvent(a.inbound, gameProfile, a.onlineMode)
+	profileRequest := NewGameProfileRequestEvent(a.inbound, originalGameProfile, a.onlineMode, useGameProfile)
 	a.eventMgr.Fire(profileRequest)
 	conn := a.inbound.delegate.MinecraftConn
 	if netmc.Closed(conn) {
 		return // Player disconnected after authentication
 	}
-	gameProfile = profileRequest.GameProfile()
+	useGameProfile = profileRequest.GameProfile()
 
 	// Initiate a regular connection and move over to it.
 	player := newConnectedPlayer(
 		conn,
-		&gameProfile,
+		&useGameProfile,
 		a.inbound.VirtualHost(),
 		a.onlineMode,
 		a.inbound.IdentifiedKey(),

pkg/edition/java/proxy/session_initial_login.go

@@ -32,9 +32,10 @@ type initialLoginSessionHandler struct {
 
 	nopSessionHandler
 
-	currentState loginState
-	login        *packet.ServerLogin
-	verify       []byte
+	currentState  loginState
+	originalLogin *packet.ServerLogin
+	useLogin      *packet.ServerLogin
+	verify        []byte
 }
 
 type loginState string
@@ -136,9 +137,9 @@ func (l *initialLoginSessionHandler) handleServerLogin(login *packet.ServerLogin
 		return
 	}
 	l.inbound.playerKey = playerKey
-	l.login = login
+	l.originalLogin = login
 
-	e := newPreLoginEvent(l.inbound, l.login.Username)
+	e := newPreLoginEvent(l.inbound, l.originalLogin.Username)
 	l.eventMgr.Fire(e)
 
 	if netmc.Closed(l.conn) {
@@ -150,6 +151,12 @@ func (l *initialLoginSessionHandler) handleServerLogin(login *packet.ServerLogin
 		return
 	}
 
+	l.useLogin = &packet.ServerLogin{
+		Username:  e.Username(),
+		PlayerKey: login.PlayerKey,
+		HolderID:  login.HolderID,
+	}
+
 	_ = l.inbound.loginEventFired(func() error {
 		if netmc.Closed(l.conn) {
 			return nil // Player was disconnected
@@ -159,7 +166,9 @@ func (l *initialLoginSessionHandler) handleServerLogin(login *packet.ServerLogin
 			(e.Result() == ForceOnlineModePreLogin || l.config().OnlineMode) {
 
 			if p, ok := netmc.Assert[GameProfileProvider](l.conn); ok {
-				sh := l.newAuthSessionHandler(l.inbound, p.GameProfile(), false)
+				useProfile := p.GameProfile()
+				useProfile.Name = l.useLogin.Username
+				sh := l.newAuthSessionHandler(l.inbound, p.GameProfile(), useProfile, false)
 				l.conn.SetSessionHandler(sh)
 				return nil
 			}
@@ -178,20 +187,26 @@ func (l *initialLoginSessionHandler) handleServerLogin(login *packet.ServerLogin
 		}
 
 		// Offline mode login
-		sh := l.newAuthSessionHandler(l.inbound, profile.NewOffline(l.login.Username), false)
+		sh := l.newAuthSessionHandler(
+			l.inbound,
+			profile.NewOffline(l.originalLogin.Username),
+			profile.NewOffline(l.useLogin.Username),
+			false)
 		l.conn.SetSessionHandler(sh)
 		return nil
 	})
 }
 
 func (l *initialLoginSessionHandler) newAuthSessionHandler(
 	inbound *loginInboundConn,
-	profile *profile.GameProfile,
+	originalProfile *profile.GameProfile,
+	useProfile *profile.GameProfile,
 	onlineMode bool,
 ) netmc.SessionHandler {
 	return newAuthSessionHandler(
 		inbound,
-		profile,
+		originalProfile,
+		useProfile,
 		onlineMode,
 		l.sessionHandlerDeps,
 	)
@@ -217,7 +232,7 @@ func (l *initialLoginSessionHandler) handleEncryptionResponse(resp *packet.Encry
 	}
 	l.currentState = encryptionResponseReceivedLoginState
 
-	if l.login == nil {
+	if l.originalLogin == nil {
 		l.log.V(1).Info("no ServerLogin packet received yet, disconnecting")
 		_ = l.conn.Close()
 		return
@@ -288,7 +303,7 @@ func (l *initialLoginSessionHandler) handleEncryptionResponse(resp *packet.Encry
 	ctx, cancel := context.WithTimeout(logr.NewContext(l.conn.Context(), log), 30*time.Second)
 	defer cancel()
 
-	authResp, err := authn.AuthenticateJoin(ctx, serverID, l.login.Username, optionalUserIP)
+	authResp, err := authn.AuthenticateJoin(ctx, serverID, l.originalLogin.Username, optionalUserIP)
 	if err != nil {
 		if errors.Is(err, context.Canceled) {
 			// The player disconnected before receiving we could authenticate.
@@ -306,16 +321,19 @@ func (l *initialLoginSessionHandler) handleEncryptionResponse(resp *packet.Encry
 	}
 
 	// Extract game profile from response.
-	gameProfile, err := authResp.GameProfile()
+	originalGameProfile, err := authResp.GameProfile()
 	if err != nil {
 		if netmc.CloseWith(l.conn, packet.DisconnectWith(unableAuthWithMojang)) == nil {
 			log.Error(err, "unable get GameProfile from Mojang authentication response")
 		}
 		return
 	}
 
+	useGameProfile := originalGameProfile
+	useGameProfile.Name = l.useLogin.Username
+
 	// All went well, initialize the session.
-	sh := l.newAuthSessionHandler(l.inbound, gameProfile, true)
+	sh := l.newAuthSessionHandler(l.inbound, originalGameProfile, useGameProfile, true)
 	l.conn.SetSessionHandler(sh)
 }