fix serverListPing while server offline

cmds/liter-server/main.go

@@ -132,6 +132,7 @@ func main(){
 	manager.SetLogger(loger)
 
 RESTART:
+	loger.Debug("Debug log enabled")
 	if _, err := os.Stat(scriptpath); errors.Is(err, os.ErrNotExist) {
 		os.MkdirAll(scriptpath, 0755)
 	}
@@ -158,7 +159,7 @@ RESTART:
 		defer func(){
 			exitch <- struct{}{}
 		}()
-		if err := server.Serve(); err != nil {
+		if err := server.Serve(); err != nil && !errors.Is(err, net.ErrClosed) {
 			loger.Errorf("Error on serve: %v", err)
 		}
 	}()
@@ -169,7 +170,7 @@ RESTART:
 WAIT:
 	select {
 	case s := <-sigs:
-		loger.Infof("Got signal %s", s.String())
+		loger.Warnf("Got signal %s", s.String())
 		if s == syscall.SIGHUP {
 			reloadConfigs()
 			ncfg := getConfig()
@@ -200,7 +201,17 @@ WAIT:
 		}
 		timeoutCtx, _ := context.WithTimeout(context.Background(), 16 * time.Second)
 		loger.Warn("Closing server...")
-		server.Shutdown(timeoutCtx)
+		done := make(chan struct{}, 0)
+		go func(){
+			defer close(done)
+			server.Shutdown(timeoutCtx)
+		}()
+		select {
+		case <-done:
+		case <-sigs:
+			loger.Errorf("Got second close signal %s", s.String())
+			os.Exit(1)
+		}
 	case <-exitch:
 		os.Exit(1)
 	}
@@ -321,12 +332,34 @@ func handler(c *liter.Conn){
 		ploger.Errorf("New connection handshake error: %v", err)
 		return
 	}
-	rc := c.RawConn()
-	go io.Copy(rc, conn.RawConn())
-	io.Copy(conn.RawConn(), rc)
+	ploger.Tracef("Handshake sent successed")
+
+	rc, cr := c.RawConn(), conn.RawConn()
+	buf := make([]byte, 32 * 1024)
+	// try read to ensure the connection is ok
+	if n, err := cr.Read(buf); err != nil {
+		ploger.Errorf("First read failed for %q: %v", svr.Target, err)
+		ploger.Debugf("Handle ping connection for server %q", svr.Id)
+		handleServerStatus(ploger, c, "Closed", svr.MotdFailed)
+		return
+	}else if _, err = rc.Write(buf[:n]); err != nil {
+		ploger.Errorf("First write failed: %v", err)
+		return
+	}
+	go func(){
+		defer c.Close()
+		defer conn.Close()
+		io.Copy(rc, cr)
+	}()
+	io.CopyBuffer(cr, rc, buf)
+}
+
+type playerInfo struct {
+	Name string `json:"name"`
+	Id   liter.UUID `json:"id"`
 }
 
-func handleServerStatus(loger logger.Logger, c *liter.Conn, name string, motd string){
+func handleServerStatus(loger logger.Logger, c *liter.Conn, status string, motd string){
 	var srp liter.StatusRequestPkt
 	var err error
 	if err = c.RecvPkt(0x00, &srp); err != nil {
@@ -336,12 +369,15 @@ func handleServerStatus(loger logger.Logger, c *liter.Conn, name string, motd st
 	if err = c.SendPkt(0x00, liter.StatusResponsePkt{
 		Payload: liter.Object{
 			"version": liter.Object{
-				"name": name,
+				"name": status,
 				"protocol": c.Protocol(),
 			},
 			"players": liter.Object{
-				"max": 1,
-				"online": 0,
+				"max": 2,
+				"online": 1,
+				"sample": []playerInfo{
+					{ Name: status }, // to allow hover for the status
+				},
 			},
 			"description": liter.Object{
 				"text": motd,

conn.go

@@ -7,12 +7,14 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"strconv"
 	"strings"
 )
 
 const DefaultPort = 25565
 
 var (
+	ErrNoRecordFound = errors.New("No DNS record was found")
 	ErrOldHandshake = errors.New("Old client(<=1.6) handshake received") // The handshake packet <= 1.6 which first byte is 0xFE
 )
 
@@ -44,24 +46,34 @@ func ResloveAddrWithContext(ctx context.Context, target string)(addr *net.TCPAdd
 	addr = &net.TCPAddr{
 		Port: DefaultPort,
 	}
-	if strings.IndexByte(target, ':') == -1 {
+	host, port, err := net.SplitHostPort(target)
+	if err != nil {
+		if strings.Contains(err.Error(), "missing port in address") {
+			host = target
+			port = ""
+			err = nil
+		}else{
+			return
+		}
+	}
+	if len(port) == 0 {
+		// if target is host only, then we lookup srv
 		var srvs []*net.SRV
-		if _, srvs, err = net.DefaultResolver.LookupSRV(ctx, "minecraft", "tcp", target); err == nil && len(srvs) > 0 {
+		if _, srvs, err = net.DefaultResolver.LookupSRV(ctx, "minecraft", "tcp", host); err == nil && len(srvs) > 0 {
 			srv := srvs[0]
-			target, addr.Port = srv.Target, (int)(srv.Port)
-		}
-		var ips []net.IP
-		if ips, err = net.LookupIP(target); err != nil {
-			return nil, err
-		}
-		addr.IP = ips[0]
-	}else{
-		if addr.IP = net.ParseIP(target); addr.IP == nil {
-			if addr, err = net.ResolveTCPAddr("tcp", target); err != nil {
-				return nil, err
-			}
+			host, addr.Port = srv.Target, (int)(srv.Port)
 		}
+	}else if addr.Port, err = strconv.Atoi(port); err != nil {
+		return
+	}
+	var ips []net.IP
+	if ips, err = net.DefaultResolver.LookupIP(ctx, "ip", host); err != nil {
+		return nil, err
+	}
+	if len(ips) == 0 {
+		return nil, ErrNoRecordFound
 	}
+	addr.IP = ips[0]
 	return
 }