Read bytes panic (#177)

* 修复 QQClint 中 netLoop c.TCP.ReadBytes 由于 conn 被设置为 nil 导致的空指针错误

Fixes: #171

.idea/.gitignore

@@ -1,8 +0,0 @@
-# Default ignored files
-/shelf/
-/workspace.xml
-# Datasource local storage ignored files
-/dataSources/
-/dataSources.local.xml
-# Editor-based HTTP Client requests
-/httpRequests/

utils/connection.go

@@ -4,12 +4,13 @@ import (
 	"encoding/binary"
 	"io"
 	"net"
-	"time"
+	"sync"
 
 	"github.com/pkg/errors"
 )
 
 type TCPListener struct {
+	lock                 sync.RWMutex
 	conn                 net.Conn
 	plannedDisconnect    func(*TCPListener)
 	unexpectedDisconnect func(*TCPListener, error)
@@ -34,42 +35,40 @@ func (t *TCPListener) Connect(addr *net.TCPAddr) error {
 	if err != nil {
 		return errors.Wrap(err, "dial tcp error")
 	}
+	t.lock.Lock()
+	defer t.lock.Unlock()
 	t.conn = conn
 	return nil
 }
 
 func (t *TCPListener) Write(buf []byte) error {
-	if t.conn == nil {
-		return ErrConnectionClosed
-	}
-	_, err := t.conn.Write(buf)
-	if err != nil {
-		if t.conn != nil {
-			t.close()
-			t.invokeUnexpectedDisconnect(err)
-		}
-		return ErrConnectionClosed
-	}
+	err := t.rLockDo(func() error {
+		_, e := t.conn.Write(buf)
+		return e
+	})
+	if err == nil {
 		return nil
 	}
 
+	t.unexpectedClose(err)
+	return ErrConnectionClosed
+}
+
 func (t *TCPListener) ReadBytes(len int) ([]byte, error) {
-	if t.conn == nil {
-		return nil, ErrConnectionClosed
-	}
 	buf := make([]byte, len)
-	_, err := io.ReadFull(t.conn, buf)
-	if err != nil {
-		time.Sleep(time.Millisecond * 100) // 服务器会发送offline包后立即断开连接, 此时还没解析, 可能还是得加锁
-		if t.conn != nil {
-			t.close()
-			t.invokeUnexpectedDisconnect(err)
-		}
-		return nil, ErrConnectionClosed
-	}
+	err := t.rLockDo(func() error {
+		_, e := io.ReadFull(t.conn, buf)
+		return e
+	})
+	if err == nil {
 		return buf, nil
 	}
 
+	//time.Sleep(time.Millisecond * 100) // 服务器会发送offline包后立即断开连接, 此时还没解析, 可能还是得加锁
+	t.unexpectedClose(err)
+	return nil, ErrConnectionClosed
+}
+
 func (t *TCPListener) ReadInt32() (int32, error) {
 	b, err := t.ReadBytes(4)
 	if err != nil {
@@ -79,20 +78,27 @@ func (t *TCPListener) ReadInt32() (int32, error) {
 }
 
 func (t *TCPListener) Close() {
-	if t.conn == nil {
-		return
-	}
+	if !t.connIsNil() {
 		t.close()
 		t.invokePlannedDisconnect()
 	}
+}
+
+func (t *TCPListener) unexpectedClose(err error) {
+	if !t.connIsNil() {
+		t.close()
+		t.invokeUnexpectedDisconnect(err)
+	}
+}
 
 func (t *TCPListener) close() {
-	if t.conn == nil {
-		return
-	}
+	t.lock.Lock()
+	defer t.lock.Unlock()
+	if t.conn != nil {
 		_ = t.conn.Close()
 		t.conn = nil
 	}
+}
 
 func (t *TCPListener) invokePlannedDisconnect() {
 	if t.plannedDisconnect != nil {
@@ -105,3 +111,18 @@ func (t *TCPListener) invokeUnexpectedDisconnect(err error) {
 		go t.unexpectedDisconnect(t, err)
 	}
 }
+
+func (t *TCPListener) rLockDo(fn func() error) error {
+	t.lock.RLock()
+	defer t.lock.RUnlock()
+	if t.conn == nil {
+		return ErrConnectionClosed
+	}
+	return fn()
+}
+
+func (t *TCPListener) connIsNil() bool {
+	t.lock.RLock()
+	defer t.lock.RUnlock()
+	return t.conn == nil
+}