net, syscall: make ECONNRESET/ECONNABORTED only temporary for Accept

Updates #6163
Fixes #24808

Change-Id: I4f5c686ebf60f72f71f566199ee3e946076202bb
Reviewed-on: https://go-review.googlesource.com/110439
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/error_nacl.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+func isConnError(err error) bool {
+	return false
+}

src/net/error_plan9.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+func isConnError(err error) bool {
+	return false
+}

src/net/error_unix.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package net
+
+import "syscall"
+
+func isConnError(err error) bool {
+	if se, ok := err.(syscall.Errno); ok {
+		return se == syscall.ECONNRESET || se == syscall.ECONNABORTED
+	}
+	return false
+}

src/net/error_windows.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+import "syscall"
+
+func isConnError(err error) bool {
+	if se, ok := err.(syscall.Errno); ok {
+		return se == syscall.WSAECONNRESET || se == syscall.WSAECONNABORTED
+	}
+	return false
+}

src/net/net.go

@@ -490,6 +490,12 @@ type temporary interface {
 }
 
 func (e *OpError) Temporary() bool {
+	// Treat ECONNRESET and ECONNABORTED as temporary errors when
+	// they come from calling accept. See issue 6163.
+	if e.Op == "accept" && isConnError(e.Err) {
+		return true
+	}
+
 	if ne, ok := e.Err.(*os.SyscallError); ok {
 		t, ok := ne.Err.(temporary)
 		return ok && t.Temporary()

src/net/net_test.go

@@ -516,3 +516,30 @@ func TestCloseUnblocksRead(t *testing.T) {
 	}
 	withTCPConnPair(t, client, server)
 }
+
+// Issue 24808: verify that ECONNRESET is not temporary for read.
+func TestNotTemporaryRead(t *testing.T) {
+	t.Parallel()
+	server := func(cs *TCPConn) error {
+		cs.SetLinger(0)
+		// Give the client time to get stuck in a Read.
+		time.Sleep(20 * time.Millisecond)
+		cs.Close()
+		return nil
+	}
+	client := func(ss *TCPConn) error {
+		_, err := ss.Read([]byte{0})
+		if err == nil {
+			return errors.New("Read succeeded unexpectedly")
+		} else if err == io.EOF {
+			// This happens on NaCl and Plan 9.
+			return nil
+		} else if ne, ok := err.(Error); !ok {
+			return fmt.Errorf("unexpected error %v", err)
+		} else if ne.Temporary() {
+			return fmt.Errorf("unexpected temporary error %v", err)
+		}
+		return nil
+	}
+	withTCPConnPair(t, client, server)
+}

src/syscall/syscall_unix.go

@@ -121,7 +121,7 @@ func (e Errno) Error() string {
 }
 
 func (e Errno) Temporary() bool {
-	return e == EINTR || e == EMFILE || e == ECONNRESET || e == ECONNABORTED || e.Timeout()
+	return e == EINTR || e == EMFILE || e.Timeout()
 }
 
 func (e Errno) Timeout() bool {

src/syscall/syscall_windows.go

@@ -110,7 +110,7 @@ func (e Errno) Error() string {
 }
 
 func (e Errno) Temporary() bool {
-	return e == EINTR || e == EMFILE || e == WSAECONNABORTED || e == WSAECONNRESET || e.Timeout()
+	return e == EINTR || e == EMFILE || e.Timeout()
 }
 
 func (e Errno) Timeout() bool {