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

ipv4/sockopt_linux.go

Index: ipv4/sockopt_linux.go
===================================================================
new file mode 100644
--- /dev/null
+++ b/ipv4/sockopt_linux.go
@@ -0,0 +1,122 @@
+// 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.
+
+package ipv4
+
+import (
+	"net"
+	"os"
+	"syscall"
+)
+
+func ipv4ReceiveTOS(fd int) (bool, error) {
+	v, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_RECVTOS)
+	if err != nil {
+		return false, os.NewSyscallError("getsockopt", err)
+	}
+	return v == 1, nil
+}
+
+func setIPv4ReceiveTOS(fd int, v bool) error {
+	err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_RECVTOS, boolint(v))
+	if err != nil {
+		return os.NewSyscallError("setsockopt", err)
+	}
+	return nil
+}
+
+func ipv4MulticastTTL(fd int) (int, error) {
+	v, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL)
+	if err != nil {
+		return 0, os.NewSyscallError("getsockopt", err)
+	}
+	return v, nil
+}
+
+func setIPv4MulticastTTL(fd int, v int) error {
+	err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_TTL, v)
+	if err != nil {
+		return os.NewSyscallError("setsockopt", err)
+	}
+	return nil
+}
+
+func ipv4PacketInfo(fd int) (bool, error) {
+	v, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_PKTINFO)
+	if err != nil {
+		return false, os.NewSyscallError("getsockopt", err)
+	}
+	return v == 1, nil
+}
+
+func setIPv4PacketInfo(fd int, v bool) error {
+	err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_PKTINFO, boolint(v))
+	if err != nil {
+		return os.NewSyscallError("setsockopt", err)
+	}
+	return nil
+}
+
+func ipv4MulticastInterface(fd int) (*net.Interface, error) {
+	mreqn, err := syscall.GetsockoptIPMreqn(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF)
+	if err != nil {
+		return nil, os.NewSyscallError("getsockopt", err)
+	}
+	if int(mreqn.Ifindex) == 0 {
+		return nil, nil
+	}
+	return net.InterfaceByIndex(int(mreqn.Ifindex))
+}
+
+func setIPv4MulticastInterface(fd int, ifi *net.Interface) error {
+	mreqn := &syscall.IPMreqn{}
+	if ifi != nil {
+		mreqn.Ifindex = int32(ifi.Index)
+	}
+	err := syscall.SetsockoptIPMreqn(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, mreqn)
+	if err != nil {
+		return os.NewSyscallError("setsockopt", err)
+	}
+	return nil
+}
+
+func ipv4MulticastLoopback(fd int) (bool, error) {
+	v, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP)
+	if err != nil {
+		return false, os.NewSyscallError("getsockopt", err)
+	}
+	return v == 1, nil
+}
+
+func setIPv4MulticastLoopback(fd int, v bool) error {
+	err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP, boolint(v))
+	if err != nil {
+		return os.NewSyscallError("setsockopt", err)
+	}
+	return nil
+}
+
+func joinIPv4Group(fd int, ifi *net.Interface, grp net.IP) error {
+	mreqn := &syscall.IPMreqn{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
+	if ifi != nil {
+		mreqn.Ifindex = int32(ifi.Index)
+	}
+	err := syscall.SetsockoptIPMreqn(fd, syscall.IPPROTO_IP, syscall.IP_ADD_MEMBERSHIP, mreqn)
+	if err != nil {
+		return os.NewSyscallError("setsockopt", err)
+	}
+	return nil
+}
+
+func leaveIPv4Group(fd int, ifi *net.Interface, grp net.IP) error {
+	mreqn := &syscall.IPMreqn{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
+	if ifi != nil {
+		mreqn.Ifindex = int32(ifi.Index)
+	}
+	err := syscall.SetsockoptIPMreqn(fd, syscall.IPPROTO_IP, syscall.IP_DROP_MEMBERSHIP, mreqn)
+	if err != nil {
+		return os.NewSyscallError("setsockopt", err)
+	}
+	return nil
+}