code review 6482044: go.net/ipv4: new package

ipv4/sockopt_bsd.go

 // Copyright 2012 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 freebsd netbsd openbsd
 
 package ipv4
 
 import (
         "net"
         "os"
         "syscall"
 )
 
-func ipv4MulticastTTL(f *os.File) (int, error) {
-        v, err := syscall.GetsockoptByte(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL)
+func ipv4MulticastTTL(fd int) (int, error) {
+        v, err := syscall.GetsockoptByte(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL)
         if err != nil {
                 return 0, os.NewSyscallError("getsockopt", err)
         }
         return int(v), nil
 }
 
-func setIPv4MulticastTTL(f *os.File, v int) error {
-        err := syscall.SetsockoptByte(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL, byte(v))
+func setIPv4MulticastTTL(fd int, v int) error {
+        err := syscall.SetsockoptByte(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL, byte(v))
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }
 
-func ipv4ReceiveDestinationAddress(f *os.File) (bool, error) {
-        v, err := syscall.GetsockoptInt(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_RECVDSTADDR)
+func ipv4ReceiveDestinationAddress(fd int) (bool, error) {
+        v, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_RECVDSTADDR)
         if err != nil {
                 return false, os.NewSyscallError("getsockopt", err)
         }
         return v == 1, nil
 }
 
-func setIPv4ReceiveDestinationAddress(f *os.File, v bool) error {
-        err := syscall.SetsockoptInt(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_RECVDSTADDR, boolint(v))
+func setIPv4ReceiveDestinationAddress(fd int, v bool) error {
+        err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_RECVDSTADDR, boolint(v))
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }
 
-func ipv4ReceiveInterface(f *os.File) (bool, error) {
-        v, err := syscall.GetsockoptInt(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_RECVIF)
+func ipv4ReceiveInterface(fd int) (bool, error) {
+        v, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_RECVIF)
         if err != nil {
                 return false, os.NewSyscallError("getsockopt", err)
         }
         return v == 1, nil
 }
 
-func setIPv4ReceiveInterface(f *os.File, v bool) error {
-        err := syscall.SetsockoptInt(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_RECVIF, boolint(v))
+func setIPv4ReceiveInterface(fd int, v bool) error {
+        err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_RECVIF, boolint(v))
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }
 
-func ipv4MulticastInterface(f *os.File) (*net.Interface, error) {
-        a, err := syscall.GetsockoptInet4Addr(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF)
+func ipv4MulticastInterface(fd int) (*net.Interface, error) {
+        a, err := syscall.GetsockoptInet4Addr(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF)
         if err != nil {
                 return nil, os.NewSyscallError("getsockopt", err)
         }
         return netIP4ToInterface(net.IPv4(a[0], a[1], a[2], a[3]))
 }
 
-func setIPv4MulticastInterface(f *os.File, ifi *net.Interface) error {
+func setIPv4MulticastInterface(fd int, ifi *net.Interface) error {
         ip, err := netInterfaceToIP4(ifi)
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
-        var x [4]byte
-        copy(x[:], ip.To4())
-        err = syscall.SetsockoptInet4Addr(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, x)
+        var a [4]byte
+        copy(a[:], ip.To4())
+        err = syscall.SetsockoptInet4Addr(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, a)
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }

[dave_cheney.net, 2012/09/03 11:04:47]

Same as below.

 
-func ipv4MulticastLoopback(f *os.File) (bool, error) {
-        v, err := syscall.GetsockoptByte(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP)
+func ipv4MulticastLoopback(fd int) (bool, error) {
+        v, err := syscall.GetsockoptByte(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP)
         if err != nil {
                 return false, os.NewSyscallError("getsockopt", err)
         }
         return v == 1, nil
 }
 
-func setIPv4MulticastLoopback(f *os.File, v bool) error {
-        err := syscall.SetsockoptByte(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP, byte(boolint(v)))
+func setIPv4MulticastLoopback(fd int, v bool) error {
+        err := syscall.SetsockoptByte(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP, byte(boolint(v)))
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil

[dave_cheney.net, 2012/09/03 11:04:47]

A version of this function exists in
http://codereview.appspot.com/6497044/diff/2002/src/pkg/net/sockoptip_bsd.go,
but this version avoids the call to fd.incref, which one is correct ?

[mikio, 2012/09/05 03:50:56]

My guess is that both fd.incref/decref are just for closing multiple socket
read/writers, network I/O goroutines, on the same socket gracefully.
So we probably might drop fd.incref/decref from socket option handlers
in net package.

 }
 
-func joinIPv4Group(f *os.File, ifi *net.Interface, grp net.IP) error {
+func joinIPv4Group(fd int, ifi *net.Interface, grp net.IP) error {
         mreq := &syscall.IPMreq{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
         if err := setSyscallIPMreq(mreq, ifi); err != nil {
                 return err
         }
-        err := syscall.SetsockoptIPMreq(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_ADD_MEMBERSHIP, mreq)
+        err := syscall.SetsockoptIPMreq(fd, syscall.IPPROTO_IP, syscall.IP_ADD_MEMBERSHIP, mreq)
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }
 
-func leaveIPv4Group(f *os.File, ifi *net.Interface, grp net.IP) error {
+func leaveIPv4Group(fd int, ifi *net.Interface, grp net.IP) error {
         mreq := &syscall.IPMreq{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
         if err := setSyscallIPMreq(mreq, ifi); err != nil {
                 return err
         }
-        err := syscall.SetsockoptIPMreq(int(f.Fd()), syscall.IPPROTO_IP, syscall.IP_DROP_MEMBERSHIP, mreq)
+        err := syscall.SetsockoptIPMreq(fd, syscall.IPPROTO_IP, syscall.IP_DROP_MEMBERSHIP, mreq)
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }