first commit

java/query.go

@@ -0,0 +1,192 @@
+package java
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/VexoraDevelopment/mcstatus/info"
+)
+
+func (c *Client) QueryFull(address string, port int) (*info.ServerInfo, error) {
+	if port == 0 {
+		port = 25565
+	}
+
+	host := address
+	p := port
+	if c.opt.EnableSRV && net.ParseIP(host) == nil {
+		if rh, rp, err := c.resolveSRV(host); err == nil && rh != "" {
+			host = rh
+			if rp != 0 {
+				p = rp
+			}
+		}
+	}
+
+	conn, _, err := c.dialUDP(host, p)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	start := time.Now()
+
+	chalPayload, err := c.writeQueryPacket(conn, 0x09, nil)
+	if err != nil {
+		return nil, err
+	}
+	chalStr := strings.TrimRight(string(chalPayload), "\x00\r\n\t ")
+	chalInt, err := strconv.Atoi(chalStr)
+	if err != nil {
+		return nil, fmt.Errorf("java query challenge parse failed: %w (payload=%q)", err, chalStr)
+	}
+
+	chal := make([]byte, 4)
+	binary.BigEndian.PutUint32(chal, uint32(chalInt))
+
+	appendData := make([]byte, 0, 8)
+	appendData = append(appendData, chal...)
+	appendData = append(appendData, 0x00, 0x00, 0x00, 0x00)
+
+	data, err := c.writeQueryPacket(conn, 0x00, appendData)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(data) < 11 {
+		return nil, errors.New("java query full stat response too short")
+	}
+	payload := data[11:]
+
+	marker := []byte{0x00, 0x00, 0x01, 'p', 'l', 'a', 'y', 'e', 'r', '_', 0x00, 0x00}
+	parts := bytes.SplitN(payload, marker, 2)
+	if len(parts) != 2 {
+		return nil, errors.New("java query parse failed: marker not found")
+	}
+	kvPart := parts[0]
+	playersPart := parts[1]
+	if len(playersPart) >= 2 {
+		playersPart = playersPart[:len(playersPart)-2]
+	}
+
+	raw := map[string]string{}
+	kvs := bytes.Split(kvPart, []byte{0x00})
+	for i := 0; i+1 < len(kvs); i += 2 {
+		k := string(kvs[i])
+		v := string(kvs[i+1])
+		if k == "" {
+			continue
+		}
+		raw[k] = v
+	}
+
+	var players []string
+	if len(playersPart) > 0 {
+		pp := bytes.Split(playersPart, []byte{0x00})
+		for _, b := range pp {
+			s := string(b)
+			if s != "" {
+				players = append(players, s)
+			}
+		}
+	}
+
+	srvInfo := &info.ServerInfo{
+		Edition:  info.EditionJava,
+		Address:  address,
+		IP:       resolveIP(address),
+		Port:     intFromMap(raw, "hostport", port),
+		MOTD:     raw["hostname"],
+		Version:  raw["version"],
+		GameMode: raw["gametype"],
+		Map:      raw["map"],
+		Game:     raw["game_id"],
+		Online:   intFromMap(raw, "numplayers", 0),
+		Slots:    intFromMap(raw, "maxplayers", 0),
+		Players:  players,
+		Query:    true,
+		RawQuery: raw,
+		Latency:  time.Since(start),
+	}
+
+	if pl := raw["plugins"]; pl != "" {
+		split := strings.SplitN(pl, ": ", 2)
+		srvInfo.Software = split[0]
+		if len(split) == 2 {
+			p2 := strings.Split(split[1], "; ")
+			clean := make([]string, 0, len(p2))
+			for _, x := range p2 {
+				x = strings.TrimSpace(x)
+				if x != "" {
+					clean = append(clean, x)
+				}
+			}
+			if len(clean) > 0 {
+				srvInfo.Plugins = clean
+			}
+		}
+	} else if eng := raw["server_engine"]; eng != "" {
+		srvInfo.Software = eng
+	}
+
+	return srvInfo, nil
+}
+
+func (c *Client) dialUDP(host string, port int) (*net.UDPConn, *net.UDPAddr, error) {
+	raddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", host, port))
+	if err != nil {
+		return nil, nil, err
+	}
+	conn, err := net.DialUDP("udp", nil, raddr)
+	if err != nil {
+		return nil, nil, err
+	}
+	if err := conn.SetDeadline(time.Now().Add(c.opt.Timeout)); err != nil {
+		_ = conn.Close()
+		return nil, nil, err
+	}
+	return conn, raddr, nil
+}
+
+func (c *Client) writeQueryPacket(conn *net.UDPConn, typ byte, appendData []byte) ([]byte, error) {
+	header := []byte{0xFE, 0xFD, typ, 0x01, 0x02, 0x03, 0x04}
+	packet := make([]byte, 0, len(header)+len(appendData))
+	packet = append(packet, header...)
+	packet = append(packet, appendData...)
+
+	if err := conn.SetDeadline(time.Now().Add(c.opt.Timeout)); err != nil {
+		return nil, err
+	}
+	if _, err := conn.Write(packet); err != nil {
+		return nil, err
+	}
+
+	buf := make([]byte, 4096)
+	n, err := conn.Read(buf)
+	if err != nil {
+		return nil, err
+	}
+	resp := buf[:n]
+	if len(resp) < 5 || resp[0] != typ {
+		return nil, errors.New("java query response validation failed")
+	}
+	return resp[5:], nil
+}
+
+func intFromMap(m map[string]string, key string, def int) int {
+	v := strings.TrimSpace(m[key])
+	if v == "" {
+		return def
+	}
+	n, err := strconv.Atoi(v)
+	if err != nil {
+		return def
+	}
+	return n
+}