New server framework, an example, and compressed packet fixed.

examples/frameworkServer/Dimension.snbt

@@ -0,0 +1,17 @@
+{
+	piglin_safe: 0b,
+	natural: 1b,
+	ambient_light: 0.0f,
+	infiniburn: "minecraft:infiniburn_overworld",
+	respawn_anchor_works: 0b,
+	has_skylight: 1b,
+	bed_works: 1b,
+	effects: "minecraft:overworld",
+	has_raids: 1b,
+	min_y: 0,
+	height: 256,
+	logical_height: 256,
+	coordinate_scale: 1.0d,
+	ultrawarm: 0b,
+	has_ceiling: 0b
+}

examples/frameworkServer/main.go

@@ -0,0 +1,159 @@
+package main
+
+import (
+	"container/list"
+	_ "embed"
+	"log"
+	"sync"
+
+	"github.com/Tnze/go-mc/chat"
+	"github.com/Tnze/go-mc/data/packetid"
+	"github.com/Tnze/go-mc/nbt"
+	"github.com/Tnze/go-mc/net"
+	pk "github.com/Tnze/go-mc/net/packet"
+	"github.com/Tnze/go-mc/server"
+	"github.com/google/uuid"
+)
+
+type MyServer struct {
+	PlayerList     *list.List
+	PlayerListLock sync.Mutex
+	server.MojangLoginHandler
+	Settings struct {
+		Name      string
+		MaxPlayer int
+		MOTD      chat.Message
+	}
+}
+
+func main() {
+	var ms MyServer
+	ms.PlayerList = list.New()
+	ms.MojangLoginHandler.OnlineMode = true
+	ms.MojangLoginHandler.Threshold = 256
+
+	ms.Settings.Name = "MyServer"
+	ms.Settings.MaxPlayer = 20
+	ms.Settings.MOTD = chat.Message{Text: "A Minecraft Server ", Extra: []chat.Message{{Text: "Powered by go-mc", Color: "yellow"}}}
+
+	s := server.Server{
+		ListPingHandler: &ms,
+		LoginHandler:    &ms,
+		GamePlay:        &ms,
+	}
+	if err := s.Listen(":25565"); err != nil {
+		log.Fatalf("Listen error: %v", err)
+	}
+}
+
+func (m *MyServer) Name() string {
+	return m.Settings.Name
+}
+
+func (m *MyServer) Protocol() int {
+	return server.ProtocolVersion
+}
+
+func (m *MyServer) MaxPlayer() int {
+	return m.Settings.MaxPlayer
+}
+
+func (m *MyServer) OnlinePlayer() int {
+	m.PlayerListLock.Lock()
+	defer m.PlayerListLock.Unlock()
+	return m.PlayerList.Len()
+}
+
+func (m *MyServer) PlayerSamples() (sample []server.PlayerSample) {
+	m.PlayerListLock.Lock()
+	defer m.PlayerListLock.Unlock()
+	// get first 10 players
+	sample = make([]server.PlayerSample, 0, 10)
+	v := m.PlayerList.Front()
+	for i := 0; i < 10; i++ {
+		if v == nil {
+			break
+		}
+		sample = append(sample, v.Value.(server.PlayerSample))
+		v = v.Next()
+	}
+	return
+}
+
+func (m *MyServer) Description() chat.Message {
+	return m.Settings.MOTD
+}
+
+func (m *MyServer) AcceptPlayer(name string, id uuid.UUID, protocol int32, conn *net.Conn) {
+	// Add player into PlayerList
+	m.PlayerListLock.Lock()
+	elem := m.PlayerList.PushBack(server.PlayerSample{
+		Name: name,
+		ID:   id,
+	})
+	m.PlayerListLock.Unlock()
+	defer func() {
+		m.PlayerListLock.Lock()
+		defer m.PlayerListLock.Unlock()
+		// remove player in PlayerList
+		m.PlayerList.Remove(elem)
+	}()
+
+	if err := m.joinGame(conn); err != nil {
+		log.Printf("Write packet fail: %v", err)
+		return
+	}
+	if err := m.playerPositionAndLook(conn); err != nil {
+		log.Printf("Write packet fail: %v", err)
+		return
+	}
+
+	var p pk.Packet
+	for {
+		err := conn.ReadPacket(&p)
+		if err != nil {
+			log.Printf("Read packet fail: %v", err)
+			break
+		}
+
+		log.Printf("Read packet: %#X", p.ID)
+	}
+}
+
+//go:embed DimensionCodec.snbt
+var dimensionCodecSNBT string
+
+//go:embed Dimension.snbt
+var dimensionSNBT string
+
+func (m *MyServer) joinGame(conn *net.Conn) error {
+	return conn.WritePacket(pk.Marshal(packetid.Login,
+		pk.Int(0),          // EntityID
+		pk.Boolean(false),  // Is hardcore
+		pk.UnsignedByte(1), // Gamemode
+		pk.Byte(1),         // Previous Gamemode
+		pk.VarInt(1),       // World Count
+		pk.Ary{Len: 1, Ary: []pk.Identifier{"world"}},      // World Names
+		pk.NBT(nbt.StringifiedMessage(dimensionCodecSNBT)), // Dimension codec
+		pk.NBT(nbt.StringifiedMessage(dimensionSNBT)),      // Dimension
+		pk.Identifier("world"),                             // World Name
+		pk.Long(0),                                         // Hashed Seed
+		pk.VarInt(m.Settings.MaxPlayer),                    // Max Players
+		pk.VarInt(15),                                      // View Distance
+		pk.Boolean(false),                                  // Reduced Debug Info
+		pk.Boolean(true),                                   // Enable respawn screen
+		pk.Boolean(false),                                  // Is Debug
+		pk.Boolean(true),                                   // Is Flat
+	))
+}
+
+func (m *MyServer) playerPositionAndLook(conn *net.Conn) error {
+	return conn.WritePacket(pk.Marshal(packetid.PositionClientbound,
+		// https://wiki.vg/index.php?title=Protocol&oldid=16067#Player_Position_And_Look_.28clientbound.29
+		pk.Double(0), pk.Double(0), pk.Double(0), // XYZ
+		pk.Float(0), pk.Float(0), // Yaw Pitch
+		pk.Byte(0),        // flag
+		pk.VarInt(0),      // TP ID
+		pk.Boolean(false), // Dismount vehicle
+	))
+}

examples/simpleServer1.17.1/main.go

@@ -148,7 +148,7 @@ func handshake(conn net.Conn) (protocol, intention int32, err error) {
 // loginSuccess send LoginSuccess packet to client
 func loginSuccess(conn net.Conn, name string, uuid uuid.UUID) error {
 	return conn.WritePacket(pk.Marshal(0x02,
-		pk.UUID(uuid), //uuid as string with hyphens
+		pk.UUID(uuid),
 		pk.String(name),
 	))
 }

net/conn.go

@@ -2,7 +2,6 @@
 package net
 
 import (
-	"bufio"
 	"crypto/cipher"
 	"io"
 	"net"
@@ -27,9 +26,10 @@ func ListenMC(addr string) (*Listener, error) {
 func (l Listener) Accept() (Conn, error) {
 	conn, err := l.Listener.Accept()
 	return Conn{
-		Socket: conn,
-		Reader: bufio.NewReader(conn),
-		Writer: conn,
+		Socket:    conn,
+		Reader:    conn,
+		Writer:    conn,
+		threshold: -1,
 	}, err
 }
 
@@ -46,9 +46,10 @@ type Conn struct {
 func DialMC(addr string) (*Conn, error) {
 	conn, err := net.Dial("tcp", addr)
 	return &Conn{
-		Socket: conn,
-		Reader: conn,
-		Writer: conn,
+		Socket:    conn,
+		Reader:    conn,
+		Writer:    conn,
+		threshold: -1,
 	}, err
 }
 
@@ -56,9 +57,10 @@ func DialMC(addr string) (*Conn, error) {
 func DialMCTimeout(addr string, timeout time.Duration) (*Conn, error) {
 	conn, err := net.DialTimeout("tcp", addr, timeout)
 	return &Conn{
-		Socket: conn,
-		Reader: conn,
-		Writer: conn,
+		Socket:    conn,
+		Reader:    conn,
+		Writer:    conn,
+		threshold: -1,
 	}, err
 }
 
@@ -66,13 +68,14 @@ func DialMCTimeout(addr string, timeout time.Duration) (*Conn, error) {
 // Helps you modify the connection process (eg. using DialContext).
 func WrapConn(conn net.Conn) *Conn {
 	return &Conn{
-		Socket: conn,
-		Reader: conn,
-		Writer: conn,
+		Socket:    conn,
+		Reader:    conn,
+		Writer:    conn,
+		threshold: -1,
 	}
 }
 
-//Close close the connection
+//Close the connection
 func (c *Conn) Close() error { return c.Socket.Close() }
 
 // ReadPacket read a Packet from Conn.
@@ -80,7 +83,7 @@ func (c *Conn) ReadPacket(p *pk.Packet) error {
 	return p.UnPack(c.Reader, c.threshold)
 }
 
-//WritePacket write a Packet to Conn.
+// WritePacket write a Packet to Conn.
 func (c *Conn) WritePacket(p pk.Packet) error {
 	return p.Pack(c.Writer, c.threshold)
 }
@@ -99,8 +102,8 @@ func (c *Conn) SetCipher(ecoStream, decoStream cipher.Stream) {
 }
 
 // SetThreshold set threshold to Conn.
-// The data packet with length longer then threshold
-// will be compress when sending.
+// The data packet with length equal or longer then threshold
+// will be compressed when sending.
 func (c *Conn) SetThreshold(t int) {
 	c.threshold = t
 }

net/packet/packet.go

@@ -36,42 +36,75 @@ func (p Packet) Scan(fields ...FieldDecoder) error {
 
 // Pack 打包一个数据包
 func (p *Packet) Pack(w io.Writer, threshold int) error {
-	var content bytes.Buffer
-	if _, err := VarInt(p.ID).WriteTo(&content); err != nil {
-		panic(err)
-	}
-	if _, err := content.Write(p.Data); err != nil {
-		panic(err)
-	}
-	if threshold > 0 { //是否启用了压缩
-		rawLen := content.Len()
-		uncompressedLen := VarInt(rawLen)
-		if rawLen > threshold { //是否需要压缩
-			compress(&content)
-		} else {
-			uncompressedLen = 0
-		}
-
-		uncompressedLenLen, _ := uncompressedLen.WriteTo(io.Discard)
-		if _, err := VarInt(uncompressedLenLen + int64(rawLen)).WriteTo(w); err != nil {
-			return err
-		}
-
-		if _, err := uncompressedLen.WriteTo(w); err != nil {
-			return err
-		}
-		if _, err := content.WriteTo(w); err != nil {
-			return err
-		}
+	if threshold >= 0 {
+		return p.withCompression(w)
 	} else {
-		if _, err := VarInt(content.Len()).WriteTo(w); err != nil {
-			return err
-		}
-		if _, err := content.WriteTo(w); err != nil {
-			return err
-		}
+		return p.withoutCompression(w)
+	}
+}
+
+func (p *Packet) withoutCompression(w io.Writer) error {
+	var buf [5]byte
+	buffer := bytes.NewBuffer(buf[:0])
+	n, err := VarInt(p.ID).WriteTo(buffer)
+	if err != nil {
+		panic(err)
+	}
+	// Length
+	_, err = VarInt(int(n) + len(p.Data)).WriteTo(w)
+	if err != nil {
+		return err
+	}
+	// Packet ID
+	_, err = buffer.WriteTo(w)
+	if err != nil {
+		return err
+	}
+	// Data
+	_, err = w.Write(p.Data)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (p *Packet) withCompression(w io.Writer) error {
+	var buff bytes.Buffer
+	zw := zlib.NewWriter(&buff)
+	n1, err := VarInt(p.ID).WriteTo(zw)
+	if err != nil {
+		return err
+	}
+	n2, err := zw.Write(p.Data)
+	if err != nil {
+		return err
+	}
+	err = zw.Close()
+	if err != nil {
+		return err
 	}
 
+	var dataLength bytes.Buffer
+	n3, err := VarInt(int(n1) + n2).WriteTo(&dataLength)
+	if err != nil {
+		return err
+	}
+
+	// Packet Length
+	_, err = VarInt(int(n3) + buff.Len()).WriteTo(w)
+	if err != nil {
+		return err
+	}
+	// Data Length
+	_, err = dataLength.WriteTo(w)
+	if err != nil {
+		return err
+	}
+	// PacketID + Data
+	_, err = buff.WriteTo(w)
+	if err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -91,7 +124,7 @@ func (p *Packet) UnPack(r io.Reader, threshold int) error {
 	buffer := bytes.NewBuffer(buf)
 
 	//解压数据
-	if threshold > 0 {
+	if threshold >= 0 {
 		if err := unCompress(buffer); err != nil {
 			return err
 		}
@@ -116,7 +149,9 @@ func unCompress(data *bytes.Buffer) error {
 	}
 
 	var uncompressedData []byte
-	if sizeUncompressed != 0 { // != 0 means compressed, let's decompress
+	if sizeUncompressed == 0 {
+		uncompressedData = data.Bytes()[1:]
+	} else { // != 0 means compressed, let's decompress
 		uncompressedData = make([]byte, sizeUncompressed)
 		r, err := zlib.NewReader(reader)
 		if err != nil {
@@ -127,23 +162,7 @@ func unCompress(data *bytes.Buffer) error {
 		if err != nil {
 			return fmt.Errorf("decompress fail: %v", err)
 		}
-	} else {
-		uncompressedData = data.Bytes()[1:]
 	}
 	*data = *bytes.NewBuffer(uncompressedData)
 	return nil
 }
-
-// compress 压缩数据
-func compress(data *bytes.Buffer) {
-	var b bytes.Buffer
-	w := zlib.NewWriter(&b)
-	if _, err := data.WriteTo(w); err != nil {
-		panic(err)
-	}
-	if err := w.Close(); err != nil {
-		panic(err)
-	}
-	*data = b
-	return
-}

server/auth/auth.go

@@ -0,0 +1,208 @@
+package auth
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha1"
+	"crypto/x509"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"github.com/Tnze/go-mc/data/packetid"
+	"io/ioutil"
+	"net/http"
+	"strings"
+
+	"github.com/Tnze/go-mc/net"
+	"github.com/Tnze/go-mc/net/CFB8"
+	pk "github.com/Tnze/go-mc/net/packet"
+	"github.com/google/uuid"
+)
+
+const verifyTokenLen = 16
+
+//Encrypt a connection, with authentication
+func Encrypt(conn *net.Conn, name string) (*Resp, error) {
+	//generate keys
+	key, err := rsa.GenerateKey(rand.Reader, 1024)
+	if err != nil {
+		return nil, err
+	}
+
+	publicKey, err := x509.MarshalPKIXPublicKey(&key.PublicKey)
+	if err != nil {
+		return nil, err
+	}
+
+	//encryption request
+	VT1, err := encryptionRequest(conn, publicKey)
+	if err != nil {
+		return nil, err
+	}
+
+	//encryption response
+	ESharedSecret, EVerifyToken, err := encryptionResponse(conn)
+	if err != nil {
+		return nil, err
+	}
+
+	//encryption the connection
+	SharedSecret, err := rsa.DecryptPKCS1v15(rand.Reader, key, ESharedSecret)
+	if err != nil {
+		return nil, err
+	}
+	VT2, err := rsa.DecryptPKCS1v15(rand.Reader, key, EVerifyToken)
+	if err != nil {
+		return nil, err
+	}
+
+	//confirm the verify token
+	if !bytes.Equal(VT1, VT2) {
+		return nil, errors.New("verify token not match")
+	}
+
+	block, err := aes.NewCipher(SharedSecret)
+	if err != nil {
+		return nil, errors.New("load aes encryption key fail")
+	}
+
+	conn.SetCipher( //启用加密
+		CFB8.NewCFB8Encrypt(block, SharedSecret),
+		CFB8.NewCFB8Decrypt(block, SharedSecret))
+
+	hash := authDigest("", SharedSecret, publicKey)
+	resp, err := authentication(name, hash) //auth
+	if err != nil {
+		return nil, errors.New("auth servers down")
+	}
+
+	return resp, nil
+}
+
+func encryptionRequest(conn *net.Conn, publicKey []byte) ([]byte, error) {
+	var verifyToken [verifyTokenLen]byte
+	_, err := rand.Read(verifyToken[:])
+	if err != nil {
+		return nil, err
+	}
+	err = conn.WritePacket(pk.Marshal(
+		packetid.EncryptionBeginClientbound,
+		pk.String(""),
+		pk.ByteArray(publicKey),
+		pk.ByteArray(verifyToken[:]),
+	))
+	return verifyToken[:], err
+}
+
+func encryptionResponse(conn *net.Conn) ([]byte, []byte, error) {
+	var p pk.Packet
+	err := conn.ReadPacket(&p)
+	if err != nil {
+		return nil, nil, err
+	}
+	if p.ID != packetid.EncryptionBeginServerbound {
+		return nil, nil, fmt.Errorf("0x%02X is not Encryption Response", p.ID)
+	}
+
+	var SharedSecret, VerifyToken pk.ByteArray
+	if err = p.Scan(&SharedSecret, &VerifyToken); err != nil {
+		return nil, nil, err
+	}
+
+	return SharedSecret, VerifyToken, nil
+}
+
+func authentication(name, hash string) (*Resp, error) {
+	resp, err := http.Get("https://sessionserver.mojang.com/session/minecraft/hasJoined?username=" + name + "&serverId=" + hash)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var Resp Resp
+	err = json.Unmarshal(body, &Resp)
+
+	return &Resp, err
+}
+
+// authDigest computes a special SHA-1 digest required for Minecraft web
+// authentication on Premium servers (online-mode=true).
+// Source: http://wiki.vg/Protocol_Encryption#Server
+//
+// Also many, many thanks to SirCmpwn and his wonderful gist (C#):
+// https://gist.github.com/SirCmpwn/404223052379e82f91e6
+func authDigest(serverID string, sharedSecret, publicKey []byte) string {
+	h := sha1.New()
+	h.Write([]byte(serverID))
+	h.Write(sharedSecret)
+	h.Write(publicKey)
+	hash := h.Sum(nil)
+
+	// Check for negative hashes
+	negative := (hash[0] & 0x80) == 0x80
+	if negative {
+		hash = twosComplement(hash)
+	}
+
+	// Trim away zeroes
+	res := strings.TrimLeft(fmt.Sprintf("%x", hash), "0")
+	if negative {
+		res = "-" + res
+	}
+
+	return res
+}
+
+// little endian
+func twosComplement(p []byte) []byte {
+	carry := true
+	for i := len(p) - 1; i >= 0; i-- {
+		p[i] = byte(^p[i])
+		if carry {
+			carry = p[i] == 0xff
+			p[i]++
+		}
+	}
+	return p
+}
+
+//Resp is the response of authentication
+type Resp struct {
+	Name       string
+	ID         uuid.UUID
+	Properties [1]struct {
+		Name, Value, Signature string
+	}
+}
+
+//Texture includes player's skin and cape
+type Texture struct {
+	TimeStamp int64     `json:"timestamp"`
+	ID        uuid.UUID `json:"profileId"`
+	Name      string    `json:"profileName"`
+	Textures  struct {
+		SKIN, CAPE struct {
+			URL string `json:"url"`
+		}
+	} `json:"textures"`
+}
+
+//Texture unmarshal the base64 encoded texture of Resp
+func (r *Resp) Texture() (t Texture, err error) {
+	var texture []byte
+	texture, err = base64.StdEncoding.DecodeString(r.Properties[0].Value)
+	if err != nil {
+		return
+	}
+
+	err = json.Unmarshal(texture, &t)
+	return
+}

server/auth/auth_test.go

@@ -0,0 +1,58 @@
+package auth
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/google/uuid"
+)
+
+func TestResp(t *testing.T) {
+	var resp Resp
+	err := json.Unmarshal([]byte(`{"id":"853c80ef3c3749fdaa49938b674adae6","name":"jeb_","properties":[{"name":"textures","value":"eyJ0aW1lc3RhbXAiOjE1NTk1NDM5MzMwMjUsInByb2ZpbGVJZCI6Ijg1M2M4MGVmM2MzNzQ5ZmRhYTQ5OTM4YjY3NGFkYWU2IiwicHJvZmlsZU5hbWUiOiJqZWJfIiwidGV4dHVyZXMiOnsiU0tJTiI6eyJ1cmwiOiJodHRwOi8vdGV4dHVyZXMubWluZWNyYWZ0Lm5ldC90ZXh0dXJlLzdmZDliYTQyYTdjODFlZWVhMjJmMTUyNDI3MWFlODVhOGUwNDVjZTBhZjVhNmFlMTZjNjQwNmFlOTE3ZTY4YjUifSwiQ0FQRSI6eyJ1cmwiOiJodHRwOi8vdGV4dHVyZXMubWluZWNyYWZ0Lm5ldC90ZXh0dXJlLzU3ODZmZTk5YmUzNzdkZmI2ODU4ODU5ZjkyNmM0ZGJjOTk1NzUxZTkxY2VlMzczNDY4YzVmYmY0ODY1ZTcxNTEifX19"}]}`), &resp)
+	if err != nil {
+		panic(err)
+	}
+	wantID := uuid.Must(uuid.Parse("853c80ef3c3749fdaa49938b674adae6"))
+
+	//check UUID
+	if resp.ID != wantID {
+		t.Errorf("uuid doesn't match: %v, want %s", resp.ID, wantID)
+	}
+
+	//check name
+	if resp.Name != "jeb_" {
+		t.Errorf("name doesn't match: %s, want %s", resp.Name, "jeb_")
+	}
+
+	//check texture
+	texture, err := resp.Texture()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Log(texture.TimeStamp)
+
+	if texture.ID != wantID {
+		t.Errorf("uuid doesn't match: %v, want %s", texture.ID, wantID)
+	}
+
+	if texture.Name != "jeb_" {
+		t.Errorf("name doesn't match: %s, want %s", texture.Name, "jeb_")
+	}
+
+	const (
+		wantSKIN = "http://textures.minecraft.net/texture/7fd9ba42a7c81eeea22f1524271ae85a8e045ce0af5a6ae16c6406ae917e68b5"
+		wantCAPE = "http://textures.minecraft.net/texture/5786fe99be377dfb6858859f926c4dbc995751e91cee373468c5fbf4865e7151"
+	)
+	if texture.Textures.SKIN.URL != wantSKIN {
+		t.Errorf("skin url not match: %s, want %s",
+			texture.Textures.SKIN.URL,
+			wantSKIN)
+	}
+	if texture.Textures.CAPE.URL != wantCAPE {
+		t.Errorf("cape url not match: %s, want %s",
+			texture.Textures.CAPE.URL,
+			wantCAPE)
+	}
+}

server/gameplay.go

@@ -0,0 +1,10 @@
+package server
+
+import (
+	"github.com/Tnze/go-mc/net"
+	"github.com/google/uuid"
+)
+
+type GamePlay interface {
+	AcceptPlayer(name string, id uuid.UUID, protocol int32, conn *net.Conn)
+}

server/handshake.go

@@ -0,0 +1,22 @@
+package server
+
+import (
+	"github.com/Tnze/go-mc/net"
+	pk "github.com/Tnze/go-mc/net/packet"
+)
+
+func (s *Server) handshake(conn *net.Conn) (protocol int32, intention int32, err error) {
+	var (
+		Protocol, Intention pk.VarInt
+		ServerAddress       pk.String        // ignored
+		ServerPort          pk.UnsignedShort // ignored
+	)
+	// receive handshake packet
+	var p pk.Packet
+	err = conn.ReadPacket(&p)
+	if err != nil {
+		return 0, 0, err
+	}
+	err = p.Scan(&Protocol, &ServerAddress, &ServerPort, &Intention)
+	return int32(Protocol), int32(Intention), err
+}

server/login.go

@@ -0,0 +1,80 @@
+package server
+
+import (
+	"fmt"
+
+	"github.com/Tnze/go-mc/data/packetid"
+	"github.com/Tnze/go-mc/net"
+	pk "github.com/Tnze/go-mc/net/packet"
+	"github.com/Tnze/go-mc/offline"
+	"github.com/Tnze/go-mc/server/auth"
+	"github.com/google/uuid"
+)
+
+type LoginHandler interface {
+	AcceptLogin(conn *net.Conn, protocol int32) (name string, id uuid.UUID, err error)
+}
+
+type MojangLoginHandler struct {
+	OnlineMode bool
+	Threshold  int
+}
+
+func (d *MojangLoginHandler) AcceptLogin(conn *net.Conn, protocol int32) (name string, id uuid.UUID, err error) {
+	//login start
+	var p pk.Packet
+	err = conn.ReadPacket(&p)
+	if err != nil {
+		return
+	}
+	if p.ID != packetid.LoginStart {
+		err = wrongPacketErr{expect: packetid.LoginStart, get: p.ID}
+		return
+	}
+
+	err = p.Scan((*pk.String)(&name)) //decode username as pk.String
+	if err != nil {
+		return
+	}
+
+	//auth
+	if d.OnlineMode {
+		var resp *auth.Resp
+		//Auth, Encrypt
+		resp, err = auth.Encrypt(conn, name)
+		if err != nil {
+			return
+		}
+		name = resp.Name
+		id = resp.ID
+	} else {
+		// offline-mode UUID
+		id = offline.NameToUUID(name)
+	}
+
+	//set compression
+	if d.Threshold >= 0 {
+		err = conn.WritePacket(pk.Marshal(
+			packetid.Compress, pk.VarInt(d.Threshold),
+		))
+		if err != nil {
+			return
+		}
+		conn.SetThreshold(d.Threshold)
+	}
+
+	// send login success
+	err = conn.WritePacket(pk.Marshal(packetid.Success,
+		pk.UUID(id),
+		pk.String(name),
+	))
+	return
+}
+
+type wrongPacketErr struct {
+	expect, get int32
+}
+
+func (w wrongPacketErr) Error() string {
+	return fmt.Sprintf("wrong packet id: expect %#02X, get %#02X", w.expect, w.get)
+}

server/ping.go

@@ -0,0 +1,74 @@
+package server
+
+import (
+	"encoding/json"
+
+	"github.com/Tnze/go-mc/chat"
+	"github.com/Tnze/go-mc/net"
+	pk "github.com/Tnze/go-mc/net/packet"
+	"github.com/google/uuid"
+)
+
+type ListPingHandler interface {
+	Name() string
+	Protocol() int
+	MaxPlayer() int
+	OnlinePlayer() int
+	PlayerSamples() []PlayerSample
+	Description() chat.Message
+}
+
+type PlayerSample struct {
+	Name string    `json:"name"`
+	ID   uuid.UUID `json:"id"`
+}
+
+func (s *Server) acceptListPing(conn *net.Conn) {
+	var p pk.Packet
+	for i := 0; i < 2; i++ { // Ping or List. Only allow check twice
+		err := conn.ReadPacket(&p)
+		if err != nil {
+			return
+		}
+
+		switch p.ID {
+		case 0x00: //List
+			var resp []byte
+			resp, err = s.listResp()
+			if err != nil {
+				break
+			}
+			err = conn.WritePacket(pk.Marshal(0x00, pk.String(resp)))
+		case 0x01: //Ping
+			err = conn.WritePacket(p)
+		}
+		if err != nil {
+			return
+		}
+	}
+}
+
+func (s *Server) listResp() ([]byte, error) {
+	var list struct {
+		Version struct {
+			Name     string `json:"name"`
+			Protocol int    `json:"protocol"`
+		} `json:"version"`
+		Players struct {
+			Max    int            `json:"max"`
+			Online int            `json:"online"`
+			Sample []PlayerSample `json:"sample"`
+		} `json:"players"`
+		Description chat.Message `json:"description"`
+		FavIcon     string       `json:"favicon,omitempty"`
+	}
+
+	list.Version.Name = s.ListPingHandler.Name()
+	list.Version.Protocol = s.ListPingHandler.Protocol()
+	list.Players.Max = s.ListPingHandler.MaxPlayer()
+	list.Players.Online = s.ListPingHandler.OnlinePlayer()
+	list.Players.Sample = s.ListPingHandler.PlayerSamples()
+	list.Description = s.ListPingHandler.Description()
+
+	return json.Marshal(list)
+}

server/server.go

@@ -0,0 +1,45 @@
+package server
+
+import "github.com/Tnze/go-mc/net"
+
+const ProtocolVersion = 756
+
+type Server struct {
+	ListPingHandler
+	LoginHandler
+	GamePlay
+}
+
+func (s *Server) Listen(addr string) error {
+	listener, err := net.ListenMC(addr)
+	if err != nil {
+		return err
+	}
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			return err
+		}
+		go s.acceptConn(&conn)
+	}
+}
+
+func (s *Server) acceptConn(conn *net.Conn) {
+	defer conn.Close()
+	protocol, intention, err := s.handshake(conn)
+	if err != nil {
+		return
+	}
+
+	switch intention {
+	case 1: // list ping
+		s.acceptListPing(conn)
+	case 2: // login
+		name, id, err := s.AcceptLogin(conn, protocol)
+		if err != nil {
+			return
+		}
+		s.AcceptPlayer(name, id, protocol, conn)
+	}
+}