net: fix inconsistent behavior across platforms in SetKeepAlivePeriod

The previous implementation used per-socket TCP keepalive options
wrong. For example, it used another level socket option to control
TCP and it didn't use TCP_KEEPINTVL option when possible.

Fixes #8683.
Fixes #8701.
Update #8679

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/136480043

src/net/tcpsockopt_darwin.go

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// TCP socket options for darwin
-
 package net
 
 import (
@@ -12,16 +10,20 @@ import (
 	"time"
 )
 
-// Set keep alive period.
+const sysTCP_KEEPINTVL = 0x101
+
 func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
 	if err := fd.incref(); err != nil {
 		return err
 	}
 	defer fd.decref()
-
 	// The kernel expects seconds so round to next highest second.
 	d += (time.Second - time.Nanosecond)
 	secs := int(d.Seconds())
-
+	switch err := syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, sysTCP_KEEPINTVL, secs); err {
+	case nil, syscall.ENOPROTOOPT: // OS X 10.7 and earlier don't support this option
+	default:
+		return os.NewSyscallError("setsockopt", err)
+	}
 	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPALIVE, secs))
 }

src/net/tcpsockopt_dragonfly.go

@@ -10,20 +10,17 @@ import (
 	"time"
 )
 
-// Set keep alive period.
 func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
 	if err := fd.incref(); err != nil {
 		return err
 	}
 	defer fd.decref()
-
-	// The kernel expects milliseconds so round to next highest millisecond.
+	// The kernel expects milliseconds so round to next highest
+	// millisecond.
 	d += (time.Millisecond - time.Nanosecond)
-	msecs := int(time.Duration(d.Nanoseconds()) / time.Millisecond)
-
-	err := os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, msecs))
-	if err != nil {
-		return err
+	msecs := int(d / time.Millisecond)
+	if err := syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, msecs); err != nil {
+		return os.NewSyscallError("setsockopt", err)
 	}
 	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, msecs))
 }

src/net/tcpsockopt_solaris.go

-// Copyright 2013 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.
-
-// TCP socket options for solaris
-
-package net
-
-import (
-	"os"
-	"syscall"
-	"time"
-)
-
-// Set keep alive period.
-func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
-	if err := fd.incref(); err != nil {
-		return err
-	}
-	defer fd.decref()
-
-	// The kernel expects seconds so round to next highest second.
-	d += (time.Second - time.Nanosecond)
-	secs := int(d.Seconds())
-
-	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.SO_KEEPALIVE, secs))
-}

src/net/tcpsockopt_openbsd.go → src/net/tcpsockopt_stub.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build nacl openbsd
+
 package net
 
 import (
@@ -10,7 +12,7 @@ import (
 )
 
 func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
-	// OpenBSD has no user-settable per-socket TCP keepalive
-	// options.
-	return syscall.EPROTONOSUPPORT
+	// NaCl and OpenBSD have no user-settable per-socket TCP
+	// keepalive options.
+	return syscall.ENOPROTOOPT
 }

src/net/tcpsockopt_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build freebsd linux nacl netbsd
+// +build freebsd linux netbsd solaris
 
 package net
 
@@ -12,20 +12,16 @@ import (
 	"time"
 )
 
-// Set keep alive period.
 func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
 	if err := fd.incref(); err != nil {
 		return err
 	}
 	defer fd.decref()
-
 	// The kernel expects seconds so round to next highest second.
 	d += (time.Second - time.Nanosecond)
 	secs := int(d.Seconds())
-
-	err := os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, secs))
-	if err != nil {
-		return err
+	if err := syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, secs); err != nil {
+		return os.NewSyscallError("setsockopt", err)
 	}
 	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, secs))
 }

src/net/tcpsockopt_windows.go

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// TCP socket options for windows
-
 package net
 
 import (
@@ -18,14 +16,14 @@ func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
 		return err
 	}
 	defer fd.decref()
-
-	// Windows expects milliseconds so round to next highest millisecond.
+	// The kernel expects milliseconds so round to next highest
+	// millisecond.
 	d += (time.Millisecond - time.Nanosecond)
-	millis := uint32(d / time.Millisecond)
+	msecs := uint32(d / time.Millisecond)
 	ka := syscall.TCPKeepalive{
 		OnOff:    1,
-		Time:     millis,
-		Interval: millis,
+		Time:     msecs,
+		Interval: msecs,
 	}
 	ret := uint32(0)
 	size := uint32(unsafe.Sizeof(ka))