net: improve test coverage for syscall.RawConn

An application using syscall.RawConn in a particular way must take
account of the operating system or platform-dependent behavior.
This change consolidates duplicate code and improves the test coverage
for applications that use socket options.

Change-Id: Ie42340ac5373875cf1fd9123df0e99a1e7ac280f
Reviewed-on: https://go-review.googlesource.com/95335Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/rawconn_stub_test.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 nacl plan9
+
+package net
+
+import (
+	"errors"
+	"syscall"
+)
+
+func readRawConn(c syscall.RawConn, b []byte) (int, error) {
+	return 0, errors.New("not supported")
+}
+
+func writeRawConn(c syscall.RawConn, b []byte) error {
+	return errors.New("not supported")
+}
+
+func controlRawConn(c syscall.RawConn, addr Addr) error {
+	return errors.New("not supported")
+}

src/net/rawconn_test.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 (
+	"bytes"
+	"runtime"
+	"testing"
+)
+
+func TestRawConnReadWrite(t *testing.T) {
+	switch runtime.GOOS {
+	case "nacl", "plan9", "windows":
+		t.Skipf("not supported on %s", runtime.GOOS)
+	}
+
+	t.Run("TCP", func(t *testing.T) {
+		handler := func(ls *localServer, ln Listener) {
+			c, err := ln.Accept()
+			if err != nil {
+				t.Error(err)
+				return
+			}
+			defer c.Close()
+
+			cc, err := ln.(*TCPListener).SyscallConn()
+			if err != nil {
+				t.Fatal(err)
+			}
+			called := false
+			op := func(uintptr) bool {
+				called = true
+				return true
+			}
+			err = cc.Write(op)
+			if err == nil {
+				t.Error("Write should return an error")
+			}
+			if called {
+				t.Error("Write shouldn't call op")
+			}
+			called = false
+			err = cc.Read(op)
+			if err == nil {
+				t.Error("Read should return an error")
+			}
+			if called {
+				t.Error("Read shouldn't call op")
+			}
+
+			var b [32]byte
+			n, err := c.Read(b[:])
+			if err != nil {
+				t.Error(err)
+				return
+			}
+			if _, err := c.Write(b[:n]); err != nil {
+				t.Error(err)
+				return
+			}
+		}
+		ls, err := newLocalServer("tcp")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer ls.teardown()
+		if err := ls.buildup(handler); err != nil {
+			t.Fatal(err)
+		}
+
+		c, err := Dial(ls.Listener.Addr().Network(), ls.Listener.Addr().String())
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer c.Close()
+
+		cc, err := c.(*TCPConn).SyscallConn()
+		if err != nil {
+			t.Fatal(err)
+		}
+		data := []byte("HELLO-R-U-THERE")
+		if err := writeRawConn(cc, data); err != nil {
+			t.Fatal(err)
+		}
+		var b [32]byte
+		n, err := readRawConn(cc, b[:])
+		if err != nil {
+			t.Fatal(err)
+		}
+		if bytes.Compare(b[:n], data) != 0 {
+			t.Fatalf("got %q; want %q", b[:n], data)
+		}
+	})
+}
+
+func TestRawConnControl(t *testing.T) {
+	switch runtime.GOOS {
+	case "nacl", "plan9":
+		t.Skipf("not supported on %s", runtime.GOOS)
+	}
+
+	t.Run("TCP", func(t *testing.T) {
+		ln, err := newLocalListener("tcp")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer ln.Close()
+
+		cc1, err := ln.(*TCPListener).SyscallConn()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := controlRawConn(cc1, ln.Addr()); err != nil {
+			t.Fatal(err)
+		}
+
+		c, err := Dial(ln.Addr().Network(), ln.Addr().String())
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer c.Close()
+
+		cc2, err := c.(*TCPConn).SyscallConn()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := controlRawConn(cc2, c.LocalAddr()); err != nil {
+			t.Fatal(err)
+		}
+
+		ln.Close()
+		if err := controlRawConn(cc1, ln.Addr()); err == nil {
+			t.Fatal("Control after Close should fail")
+		}
+		c.Close()
+		if err := controlRawConn(cc2, c.LocalAddr()); err == nil {
+			t.Fatal("Control after Close should fail")
+		}
+	})
+}

src/net/rawconn_unix_test.go

@@ -6,139 +6,86 @@
 
 package net
 
-import (
-	"bytes"
-	"syscall"
-	"testing"
-)
-
-func TestRawConn(t *testing.T) {
-	handler := func(ls *localServer, ln Listener) {
-		c, err := ln.Accept()
-		if err != nil {
-			t.Error(err)
-			return
-		}
-		defer c.Close()
-		var b [32]byte
-		n, err := c.Read(b[:])
-		if err != nil {
-			t.Error(err)
-			return
-		}
-		if _, err := c.Write(b[:n]); err != nil {
-			t.Error(err)
-			return
-		}
-	}
-	ls, err := newLocalServer("tcp")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer ls.teardown()
-	if err := ls.buildup(handler); err != nil {
-		t.Fatal(err)
-	}
-
-	c, err := Dial(ls.Listener.Addr().Network(), ls.Listener.Addr().String())
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer c.Close()
-	cc, err := c.(*TCPConn).SyscallConn()
-	if err != nil {
-		t.Fatal(err)
-	}
+import "syscall"
 
+func readRawConn(c syscall.RawConn, b []byte) (int, error) {
 	var operr error
-	data := []byte("HELLO-R-U-THERE")
-	err = cc.Write(func(s uintptr) bool {
-		_, operr = syscall.Write(int(s), data)
+	var n int
+	err := c.Read(func(s uintptr) bool {
+		n, operr = syscall.Read(int(s), b)
 		if operr == syscall.EAGAIN {
 			return false
 		}
 		return true
 	})
-	if err != nil || operr != nil {
-		t.Fatal(err, operr)
+	if err != nil {
+		return n, err
 	}
+	if operr != nil {
+		return n, operr
+	}
+	return n, nil
+}
 
-	var nr int
-	var b [32]byte
-	err = cc.Read(func(s uintptr) bool {
-		nr, operr = syscall.Read(int(s), b[:])
+func writeRawConn(c syscall.RawConn, b []byte) error {
+	var operr error
+	err := c.Write(func(s uintptr) bool {
+		_, operr = syscall.Write(int(s), b)
 		if operr == syscall.EAGAIN {
 			return false
 		}
 		return true
 	})
-	if err != nil || operr != nil {
-		t.Fatal(err, operr)
-	}
-	if bytes.Compare(b[:nr], data) != 0 {
-		t.Fatalf("got %#v; want %#v", b[:nr], data)
-	}
-
-	fn := func(s uintptr) {
-		operr = syscall.SetsockoptInt(int(s), syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
-	}
-	err = cc.Control(fn)
-	if err != nil || operr != nil {
-		t.Fatal(err, operr)
-	}
-	c.Close()
-	err = cc.Control(fn)
-	if err == nil {
-		t.Fatal("should fail")
-	}
-}
-
-func TestRawConnListener(t *testing.T) {
-	ln, err := newLocalListener("tcp")
 	if err != nil {
-		t.Fatal(err)
-	}
-	defer ln.Close()
-
-	cc, err := ln.(*TCPListener).SyscallConn()
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	called := false
-	op := func(uintptr) bool {
-		called = true
-		return true
-	}
-
-	err = cc.Write(op)
-	if err == nil {
-		t.Error("Write should return an error")
-	}
-	if called {
-		t.Error("Write shouldn't call op")
+		return err
 	}
-
-	called = false
-	err = cc.Read(op)
-	if err == nil {
-		t.Error("Read should return an error")
-	}
-	if called {
-		t.Error("Read shouldn't call op")
+	if operr != nil {
+		return operr
 	}
+	return nil
+}
 
+func controlRawConn(c syscall.RawConn, addr Addr) error {
 	var operr error
 	fn := func(s uintptr) {
 		_, operr = syscall.GetsockoptInt(int(s), syscall.SOL_SOCKET, syscall.SO_REUSEADDR)
+		if operr != nil {
+			return
+		}
+		switch addr := addr.(type) {
+		case *TCPAddr:
+			// There's no guarantee that IP-level socket
+			// options work well with dual stack sockets.
+			// A simple solution would be to take a look
+			// at the bound address to the raw connection
+			// and to classify the address family of the
+			// underlying socket by the bound address:
+			//
+			// - When IP.To16() != nil and IP.To4() == nil,
+			//   we can assume that the raw connection
+			//   consists of an IPv6 socket using only
+			//   IPv6 addresses.
+			//
+			// - When IP.To16() == nil and IP.To4() != nil,
+			//   the raw connection consists of an IPv4
+			//   socket using only IPv4 addresses.
+			//
+			// - Otherwise, the raw connection is a dual
+			//   stack socket, an IPv6 socket using IPv6
+			//   addresses including IPv4-mapped or
+			//   IPv4-embedded IPv6 addresses.
+			if addr.IP.To16() != nil && addr.IP.To4() == nil {
+				operr = syscall.SetsockoptInt(int(s), syscall.IPPROTO_IPV6, syscall.IPV6_UNICAST_HOPS, 1)
+			} else if addr.IP.To16() == nil && addr.IP.To4() != nil {
+				operr = syscall.SetsockoptInt(int(s), syscall.IPPROTO_IP, syscall.IP_TTL, 1)
+			}
+		}
 	}
-	err = cc.Control(fn)
-	if err != nil || operr != nil {
-		t.Fatal(err, operr)
+	if err := c.Control(fn); err != nil {
+		return err
 	}
-	ln.Close()
-	err = cc.Control(fn)
-	if err == nil {
-		t.Fatal("Control after Close should fail")
+	if operr != nil {
+		return operr
 	}
+	return nil
 }

src/net/rawconn_windows_test.go

@@ -6,84 +6,60 @@ package net
 
 import (
 	"syscall"
-	"testing"
 	"unsafe"
 )
 
-func TestRawConn(t *testing.T) {
-	c, err := newLocalPacketListener("udp")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer c.Close()
-	cc, err := c.(*UDPConn).SyscallConn()
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	var operr error
-	fn := func(s uintptr) {
-		operr = syscall.SetsockoptInt(syscall.Handle(s), syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
-	}
-	err = cc.Control(fn)
-	if err != nil || operr != nil {
-		t.Fatal(err, operr)
-	}
-	c.Close()
-	err = cc.Control(fn)
-	if err == nil {
-		t.Fatal("should fail")
-	}
+func readRawConn(c syscall.RawConn, b []byte) (int, error) {
+	return 0, syscall.EWINDOWS
 }
 
-func TestRawConnListener(t *testing.T) {
-	ln, err := newLocalListener("tcp")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer ln.Close()
-
-	cc, err := ln.(*TCPListener).SyscallConn()
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	called := false
-	op := func(uintptr) bool {
-		called = true
-		return true
-	}
-
-	err = cc.Write(op)
-	if err == nil {
-		t.Error("Write should return an error")
-	}
-	if called {
-		t.Error("Write shouldn't call op")
-	}
-
-	called = false
-	err = cc.Read(op)
-	if err == nil {
-		t.Error("Read should return an error")
-	}
-	if called {
-		t.Error("Read shouldn't call op")
-	}
+func writeRawConn(c syscall.RawConn, b []byte) error {
+	return syscall.EWINDOWS
+}
 
+func controlRawConn(c syscall.RawConn, addr Addr) error {
 	var operr error
 	fn := func(s uintptr) {
 		var v, l int32
 		l = int32(unsafe.Sizeof(v))
 		operr = syscall.Getsockopt(syscall.Handle(s), syscall.SOL_SOCKET, syscall.SO_REUSEADDR, (*byte)(unsafe.Pointer(&v)), &l)
+		if operr != nil {
+			return
+		}
+		switch addr := addr.(type) {
+		case *TCPAddr:
+			// There's no guarantee that IP-level socket
+			// options work well with dual stack sockets.
+			// A simple solution would be to take a look
+			// at the bound address to the raw connection
+			// and to classify the address family of the
+			// underlying socket by the bound address:
+			//
+			// - When IP.To16() != nil and IP.To4() == nil,
+			//   we can assume that the raw connection
+			//   consists of an IPv6 socket using only
+			//   IPv6 addresses.
+			//
+			// - When IP.To16() == nil and IP.To4() != nil,
+			//   the raw connection consists of an IPv4
+			//   socket using only IPv4 addresses.
+			//
+			// - Otherwise, the raw connection is a dual
+			//   stack socket, an IPv6 socket using IPv6
+			//   addresses including IPv4-mapped or
+			//   IPv4-embedded IPv6 addresses.
+			if addr.IP.To16() != nil && addr.IP.To4() == nil {
+				operr = syscall.SetsockoptInt(syscall.Handle(s), syscall.IPPROTO_IPV6, syscall.IPV6_UNICAST_HOPS, 1)
+			} else if addr.IP.To16() == nil && addr.IP.To4() != nil {
+				operr = syscall.SetsockoptInt(syscall.Handle(s), syscall.IPPROTO_IP, syscall.IP_TTL, 1)
+			}
+		}
 	}
-	err = cc.Control(fn)
-	if err != nil || operr != nil {
-		t.Fatal(err, operr)
+	if err := c.Control(fn); err != nil {
+		return err
 	}
-	ln.Close()
-	err = cc.Control(fn)
-	if err == nil {
-		t.Fatal("Control after Close should fail")
+	if operr != nil {
+		return operr
 	}
+	return nil
 }