Add Votifier 2 support

config.example.yml

@@ -77,4 +77,9 @@ bedrock_edition:
         random: false
         min: 0
         max: 0
-    gamemode: survival
+    gamemode: survival
+votifier:
+  enable: true
+  host: 0.0.0.0
+  port: 8192
+  token: abc123

src/config/config.go

@@ -94,6 +94,12 @@ type Config struct {
 			Gamemode string `yaml:"gamemode"`
 		} `yaml:"options"`
 	} `yaml:"bedrock_edition"`
+	Votifier struct {
+		Enable bool   `yaml:"enable"`
+		Host   string `yaml:"host"`
+		Port   uint16 `yaml:"port"`
+		Token  string `yaml:"token"`
+	} `yaml:"votifier"`
 }
 
 // ReadFile reads the YAML file from the path.

src/main.go

@@ -10,6 +10,7 @@ import (
 	"main/src/java"
 	"main/src/query"
 	"main/src/util"
+	"main/src/vote"
 )
 
 var (
@@ -47,6 +48,14 @@ func init() {
 		log.Printf("Listening for query connections on %s:%d\n", conf.JavaEdition.Query.Host, conf.JavaEdition.Query.Port)
 	}
 
+	if conf.Votifier.Enable {
+		if err = vote.Listen(conf); err != nil {
+			log.Fatal(err)
+		}
+
+		log.Printf("Listening for Votifier on %s:%d\n", conf.Votifier.Host, conf.Votifier.Port)
+	}
+
 	util.SetSamplePlayers(conf.JavaEdition.Options.Players.Sample)
 }
 
@@ -69,6 +78,12 @@ func main() {
 		go query.AcceptConnections()
 	}
 
+	if conf.Votifier.Enable {
+		defer vote.Close()
+
+		go vote.AcceptConnections()
+	}
+
 	s := make(chan os.Signal, 1)
 	signal.Notify(s, os.Interrupt)
 	<-s

src/vote/protocol.go

@@ -0,0 +1,114 @@
+package vote
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+type voteMessage struct {
+	Payload   string `json:"payload"`
+	Signature string `json:"signature"`
+}
+
+type votePayload struct {
+	ServiceName string `json:"serviceName"`
+	Username    string `json:"username"`
+	Timestamp   int64  `json:"timestamp"`
+	Challenge   string `json:"challenge"`
+	UUID        string `json:"uuid"`
+}
+
+type voteResponse struct {
+	Status string `json:"status"`
+	Error  string `json:"error"`
+}
+
+func sendHandshake(w io.Writer, challenge string) error {
+	_, err := w.Write([]byte(fmt.Sprintf("VOTIFIER 2 %s\n", challenge)))
+
+	return err
+}
+
+func readPayload(r io.Reader, challenge string) error {
+	var (
+		identifier    int16
+		messageLength int16
+	)
+
+	if err := binary.Read(r, binary.BigEndian, &identifier); err != nil {
+		return err
+	}
+
+	if identifier != 0x733A {
+		return fmt.Errorf("invalid identifier: %X", identifier)
+	}
+
+	if err := binary.Read(r, binary.BigEndian, &messageLength); err != nil {
+		return err
+	}
+
+	data := make([]byte, messageLength)
+
+	if _, err := r.Read(data); err != nil {
+		return err
+	}
+
+	var message voteMessage
+
+	if err := json.Unmarshal(data, &message); err != nil {
+		return err
+	}
+
+	var payload votePayload
+
+	if err := json.Unmarshal([]byte(message.Payload), &payload); err != nil {
+		return err
+	}
+
+	if payload.Challenge != challenge {
+		return fmt.Errorf("unexpected challenge: %s", payload.Challenge)
+	}
+
+	hash := hmac.New(sha256.New, []byte(conf.Votifier.Token))
+	hash.Write([]byte(message.Payload))
+
+	if base64.StdEncoding.EncodeToString(hash.Sum(nil)) != message.Signature {
+		return fmt.Errorf("invalid message signature (is the token wrong?): %s", message.Signature)
+	}
+
+	return nil
+}
+
+func writeResponse(w io.Writer) error {
+	data, err := json.Marshal(voteResponse{
+		Status: "ok",
+	})
+
+	if err != nil {
+		return err
+	}
+
+	_, err = w.Write(append(data, '\n'))
+
+	return err
+}
+
+func writeError(w io.Writer, message string) error {
+	data, err := json.Marshal(voteResponse{
+		Status: "error",
+		Error:  message,
+	})
+
+	if err != nil {
+		return err
+	}
+
+	_, err = w.Write(append(data, '\n'))
+
+	return err
+}

src/vote/socket.go

@@ -0,0 +1,64 @@
+package vote
+
+import (
+	"fmt"
+	"net"
+
+	"main/src/config"
+)
+
+var (
+	socket net.Listener   = nil
+	conf   *config.Config = nil
+)
+
+// Listen creates a new TCP socket server using the address specified in the configuration file.
+func Listen(c *config.Config) (err error) {
+	conf = c
+
+	socket, err = net.Listen("tcp", fmt.Sprintf("%s:%d", c.Votifier.Host, c.Votifier.Port))
+
+	return
+}
+
+// Close closes the socket server.
+func Close() error {
+	return socket.Close()
+}
+
+// AcceptConnections should be started in a Goroutine and accepts new connections from the socket server.
+func AcceptConnections() {
+	for {
+		conn, err := socket.Accept()
+
+		if err != nil {
+			continue
+		}
+
+		go handleConnection(conn)
+	}
+}
+
+func handleConnection(conn net.Conn) {
+	defer conn.Close()
+
+	challenge := generateChallenge()
+
+	if err := sendHandshake(conn, challenge); err != nil {
+		writeError(conn, err.Error())
+
+		return
+	}
+
+	if err := readPayload(conn, challenge); err != nil {
+		writeError(conn, err.Error())
+
+		return
+	}
+
+	if err := writeResponse(conn); err != nil {
+		writeError(conn, err.Error())
+
+		return
+	}
+}

src/vote/util.go

@@ -0,0 +1,16 @@
+package vote
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+)
+
+func generateChallenge() string {
+	data := make([]byte, 8)
+
+	if _, err := rand.Read(data); err != nil {
+		panic(err)
+	}
+
+	return hex.EncodeToString(data)
+}