code review 6497044: net: delete unused IP-level socket option helpers

src/pkg/net/sockoptip_bsd.go

 // Copyright 2011 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
 
 // IP-level socket options for BSD variants
 
 package net
 
 import (
         "os"
         "syscall"
 )
 
-func ipv4MulticastTTL(fd *netFD) (int, error) {
-        if err := fd.incref(false); err != nil {
-                return 0, err
+func setIPv4MulticastInterface(fd *netFD, ifi *Interface) error {
+        ip, err := interfaceToIPv4Addr(ifi)
+        if err != nil {
+                return os.NewSyscallError("setsockopt", err)
         }
-        defer fd.decref()
-        v, err := syscall.GetsockoptByte(fd.sysfd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL)
-        if err != nil {
-                return 0, os.NewSyscallError("getsockopt", err)
-        }
-        return int(v), nil
-}
-
-func setIPv4MulticastTTL(fd *netFD, v int) error {
+        var x [4]byte
+        copy(x[:], ip.To4())
         if err := fd.incref(false); err != nil {
                 return err
         }
         defer fd.decref()
-        err := syscall.SetsockoptByte(fd.sysfd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL, byte(v))
+        err = syscall.SetsockoptInet4Addr(fd.sysfd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, x)
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }
 
-func ipv6TrafficClass(fd *netFD) (int, error) {
-        if err := fd.incref(false); err != nil {
-                return 0, err
-        }
-        defer fd.decref()
-        v, err := syscall.GetsockoptInt(fd.sysfd, syscall.IPPROTO_IPV6, syscall.IPV6_TCLASS)
-        if err != nil {
-                return 0, os.NewSyscallError("getsockopt", err)
-        }
-        return v, nil
-}
-
-func setIPv6TrafficClass(fd *netFD, v int) error {
+func setIPv4MulticastLoopback(fd *netFD, v bool) error {
         if err := fd.incref(false); err != nil {
                 return err
         }
         defer fd.decref()
-        err := syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_IPV6, syscall.IPV6_TCLASS, v)
+        err := syscall.SetsockoptByte(fd.sysfd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP, byte(boolint(v)))
         if err != nil {
                 return os.NewSyscallError("setsockopt", err)
         }
         return nil
 }