ce7cb702218693d08ea6d83464d2457c9250027c

packages/grafana-rcon/backend/rcon.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"strings"
+	"time"
+
+	"github.com/gorcon/rcon"
+)
+
+const (
+	authID = 0
+	cmdID  = 1
+	endID  = 2
+)
+
+func authenticate(conn net.Conn, password string) error {
+	if _, err := rcon.NewPacket(rcon.SERVERDATA_AUTH, authID, password).WriteTo(conn); err != nil {
+		return err
+	}
+	var packet rcon.Packet
+	if _, err := packet.ReadFrom(conn); err != nil {
+		return err
+	}
+	if packet.Type != rcon.SERVERDATA_AUTH_RESPONSE {
+		return rcon.ErrInvalidAuthResponse
+	}
+	if packet.ID == -1 {
+		return rcon.ErrAuthFailed
+	}
+	if packet.ID != authID {
+		return rcon.ErrInvalidPacketID
+	}
+	return nil
+}
+
+func withRcon(ctx context.Context, address, password string, action func(net.Conn) (string, error)) (string, error) {
+	dialer := net.Dialer{Timeout: rcon.DefaultDialTimeout}
+	conn, err := dialer.DialContext(ctx, "tcp", address)
+	if err != nil {
+		return "", err
+	}
+	defer conn.Close()
+	cancel := context.AfterFunc(ctx, func() { _ = conn.Close() })
+	defer cancel()
+	if err := conn.SetDeadline(time.Now().Add(rcon.DefaultDeadline)); err != nil {
+		return "", err
+	}
+	if err := authenticate(conn, password); err != nil {
+		return "", err
+	}
+	if err := conn.SetDeadline(time.Now().Add(rcon.DefaultDeadline)); err != nil {
+		return "", err
+	}
+	return action(conn)
+}
+
+func checkRcon(ctx context.Context, address, password string) error {
+	_, err := withRcon(ctx, address, password, func(net.Conn) (string, error) { return "", nil })
+	return err
+}
+
+func execute(ctx context.Context, address, password, command string) (string, error) {
+	return withRcon(ctx, address, password, func(conn net.Conn) (string, error) {
+		if _, err := rcon.NewPacket(rcon.SERVERDATA_EXECCOMMAND, cmdID, command).WriteTo(conn); err != nil {
+			return "", err
+		}
+		var first rcon.Packet
+		if _, err := first.ReadFrom(conn); err != nil {
+			return "", err
+		}
+		if first.ID != cmdID || first.Type != rcon.SERVERDATA_RESPONSE_VALUE {
+			return "", fmt.Errorf("unexpected RCON response")
+		}
+		// Wait for the command response before sending the delimiter; Minecraft drops pipelined requests.
+		if _, err := rcon.NewPacket(rcon.SERVERDATA_RESPONSE_VALUE, endID, "").WriteTo(conn); err != nil {
+			return "", err
+		}
+		var output strings.Builder
+		output.WriteString(first.Body())
+		for {
+			var packet rcon.Packet
+			if _, err := packet.ReadFrom(conn); err != nil {
+				return "", err
+			}
+			if packet.ID == endID {
+				return output.String(), nil
+			}
+			if packet.ID != cmdID || packet.Type != rcon.SERVERDATA_RESPONSE_VALUE {
+				return "", fmt.Errorf("unexpected RCON response")
+			}
+			output.WriteString(packet.Body())
+		}
+	})
+}