From 476caaac4fe613fb0c35cb8119985c0127500ebc Mon Sep 17 00:00:00 2001
From: "yuyu.zx" <yuyu.zx@alipay.com>
Date: Wed, 6 Apr 2022 18:21:09 +0800
Subject: [PATCH] Ftr: check connection aliveness

---
 net/conncheck.go       | 72 ++++++++++++++++++++++++++++++++++++++++++
 net/conncheck_dummy.go | 36 +++++++++++++++++++++
 2 files changed, 108 insertions(+)
 create mode 100644 net/conncheck.go
 create mode 100644 net/conncheck_dummy.go

diff --git a/net/conncheck.go b/net/conncheck.go
new file mode 100644
index 0000000..46e513d
--- /dev/null
+++ b/net/conncheck.go
@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
+//
+// Copyright 2019 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// +build linux darwin dragonfly freebsd netbsd openbsd solaris illumos
+
+package gxnet
+
+import (
+	"errors"
+	"io"
+	"net"
+	"syscall"
+)
+
+var errUnexpectedRead = errors.New("unexpected read from socket")
+
+func connCheck(conn net.Conn) error {
+	var sysErr error
+
+	sysConn, ok := conn.(syscall.Conn)
+	if !ok {
+		return nil
+	}
+	rawConn, err := sysConn.SyscallConn()
+	if err != nil {
+		return err
+	}
+
+	err = rawConn.Read(func(fd uintptr) bool {
+		var buf [1]byte
+		n, err := syscall.Read(int(fd), buf[:])
+		switch {
+		case n == 0 && err == nil:
+			sysErr = io.EOF
+		case n > 0:
+			sysErr = errUnexpectedRead
+		case err == syscall.EAGAIN || err == syscall.EWOULDBLOCK:
+			sysErr = nil
+		default:
+			sysErr = err
+		}
+		return true
+	})
+	if err != nil {
+		return err
+	}
+
+	return sysErr
+}
+
diff --git a/net/conncheck_dummy.go b/net/conncheck_dummy.go
new file mode 100644
index 0000000..9395ae6
--- /dev/null
+++ b/net/conncheck_dummy.go
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
+//
+// Copyright 2019 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// +build !linux,!darwin,!dragonfly,!freebsd,!netbsd,!openbsd,!solaris,!illumos
+
+package gxnet
+
+import (
+	"net"
+)
+
+func connCheck(conn net.Conn) error {
+	return nil
+}