net.Listener.ApprovePlayer

main.go

@@ -28,7 +28,11 @@ func main() {
 
 	cfg := loadConfig()
 
-	w := world.NewWorld(cfg.LevelName)
+	w, err := world.NewWorld(cfg.LevelName)
+	if err != nil {
+		log.Errorlnf("Error preparing level: %v", w)
+		return
+	}
 
 	log.Infof("Binding server to %s:%d\n", cfg.ServerIp, cfg.ServerPort)
 

net/config.go

@@ -6,6 +6,7 @@ import (
 	"net"
 
 	"github.com/zeppelinmc/zeppelin/net/packet/status"
+	"github.com/zeppelinmc/zeppelin/text"
 )
 
 type Config struct {
@@ -34,6 +35,9 @@ func (c Config) New() (*Listener, error) {
 
 		newConns: make(chan *Conn),
 		err:      make(chan error),
+		ApprovePlayer: func(c *Conn) (ok bool, disconnectionReason *text.TextComponent) {
+			return true, nil
+		},
 	}
 	lis.privKey, err = rsa.GenerateKey(rand.Reader, 1024)
 

net/conn.go

@@ -86,9 +86,9 @@ var pkpool = sync.Pool{
 }
 
 func (conn *Conn) WritePacket(pk packet.Packet) error {
-	var packetBuf = pkbufpool.Get().(*bytes.Buffer)
+	var packetBuf = pkpool.Get().(*bytes.Buffer)
 	packetBuf.Reset()
-	defer pkbufpool.Put(packetBuf)
+	defer pkpool.Put(packetBuf)
 
 	w := io.NewWriter(packetBuf)
 
@@ -402,6 +402,15 @@ func (conn *Conn) handleHandshake() bool {
 		if !ok {
 			return false
 		}
+		if ok, r := conn.listener.ApprovePlayer(conn); !ok {
+			var reason = text.Sprint("Disconnected")
+			if r != nil {
+				reason = *r
+			}
+			conn.WritePacket(&login.Disconnect{Reason: reason})
+			conn.Close()
+			return false
+		}
 		conn.username = loginStart.Name
 		conn.uuid = loginStart.PlayerUUID
 

net/listener.go

@@ -4,6 +4,8 @@ import (
 	"crypto/rsa"
 	"fmt"
 	"net"
+
+	"github.com/zeppelinmc/zeppelin/text"
 )
 
 const (
@@ -22,6 +24,8 @@ type Listener struct {
 	net.Listener
 	cfg Config
 
+	ApprovePlayer func(*Conn) (ok bool, disconnectionReason *text.TextComponent)
+
 	newConns chan *Conn
 	err      chan error
 

server/player/list/playerlist.go

@@ -0,0 +1,15 @@
+// Package list provides parsing of playerlist files (whitelist.json, ops.json etc)
+
+package list
+
+type WhitelistPlayer struct {
+	UUID string `json:"uuid"`
+	Name string `json:"name"`
+}
+
+type OperatorPlayer struct {
+	UUID                string `json:"uuid"`
+	Name                string `json:"name"`
+	Level               int32  `json:"level"`
+	BypassesPlayerLimit bool   `json:"bypassesPlayerLimit"`
+}

server/world/level/level.go

@@ -16,6 +16,8 @@ import (
 	"github.com/zeppelinmc/zeppelin/server/world/level/seed"
 )
 
+var SessionLock = []byte{0xE2, 0x98, 0x83}
+
 // A game rule is a string containing an integer or a boolean
 type GameRule string
 

server/world/world.go

@@ -1,6 +1,7 @@
 package world
 
 import (
+	"fmt"
 	"os"
 	"strings"
 
@@ -19,11 +20,13 @@ type World struct {
 
 	levelPrepared bool
 
+	lock *os.File
+
 	path              string
 	worldAge, dayTime atomic.AtomicValue[int64]
 }
 
-func NewWorld(path string) *World {
+func NewWorld(path string) (*World, error) {
 	var err error
 	w := &World{
 		path:      path,
@@ -33,6 +36,11 @@ func NewWorld(path string) *World {
 	if err != nil {
 		w.prepareLevel()
 	}
+
+	if w.obtainLock() != nil {
+		return nil, fmt.Errorf("failed to obtain session.lock")
+	}
+
 	w.worldAge = atomic.Value(w.Level.Data.Time)
 	w.dayTime = atomic.Value(w.Level.Data.DayTime)
 	w.dimensions = map[string]*dimension.Dimension{
@@ -46,7 +54,7 @@ func NewWorld(path string) *World {
 		),
 	}
 
-	return w
+	return w, nil
 }
 
 func (w *World) prepareLevel() {
@@ -60,6 +68,16 @@ func (w *World) prepareLevel() {
 	os.MkdirAll(w.path+"/DIM1/region", 0755)
 }
 
+func (w *World) obtainLock() error {
+	f, err := os.OpenFile(w.path+"/session.lock", os.O_RDWR|os.O_CREATE, 0755)
+	if err != nil {
+		return err
+	}
+	f.Write(level.SessionLock)
+	w.lock = f
+	return nil
+}
+
 // returns the dimension struct for the dimension name
 func (w *World) Dimension(name string) *dimension.Dimension {
 	if !strings.Contains(name, ":") {
@@ -74,6 +92,7 @@ func (w *World) Save() {
 		dim.Save()
 		log.Infoln("Saved dimension", dim.Name())
 	}
+	w.lock.Close()
 }
 
 func (w *World) RegisterDimension(name string, dim *dimension.Dimension) {