net: support JoinSourceSpecificGroup and LeaveSourceSpecificGroup for…

ipv4/sockopt.go

@@ -33,6 +33,7 @@ const (
 const (
 	ssoTypeIPMreq = iota + 1
 	ssoTypeIPMreqn
+	ssoTypeIPMreqSource
 	ssoTypeGroupReq
 	ssoTypeGroupSourceReq
 )

ipv4/sockopt_posix.go

@@ -63,7 +63,12 @@ func (so *sockOpt) setGroup(c *socket.Conn, ifi *net.Interface, grp net.IP) erro
 }
 
 func (so *sockOpt) setSourceGroup(c *socket.Conn, ifi *net.Interface, grp, src net.IP) error {
-	return so.setGroupSourceReq(c, ifi, grp, src)
+	switch so.typ {
+	case ssoTypeIPMreqSource:
+		return so.setIPMreqSource(c, ifi, grp, src)
+	default:
+		return so.setGroupSourceReq(c, ifi, grp, src)
+	}
 }
 
 func (so *sockOpt) setBPF(c *socket.Conn, f []bpf.RawInstruction) error {

ipv4/sys_asmreq.go

@@ -25,6 +25,18 @@ func (so *sockOpt) setIPMreq(c *socket.Conn, ifi *net.Interface, grp net.IP) err
 	return so.Set(c, b)
 }
 
+func (so *sockOpt) setIPMreqSource(c *socket.Conn, ifi *net.Interface, grp, src net.IP) error {
+	mreqSource := ipMreqSource{
+		Multiaddr:  [4]byte{grp[0], grp[1], grp[2], grp[3]},
+		Sourceaddr: [4]byte{src[0], src[1], src[2], src[3]},
+	}
+	if err := setIPMreqSourceInterface(&mreqSource, ifi); err != nil {
+		return err
+	}
+	b := (*[sizeofIPMreqSource]byte)(unsafe.Pointer(&mreqSource))[:sizeofIPMreqSource]
+	return so.Set(c, b)
+}
+
 func (so *sockOpt) getMulticastIf(c *socket.Conn) (*net.Interface, error) {
 	var b [4]byte
 	if _, err := so.Get(c, b[:]); err != nil {
@@ -72,6 +84,31 @@ func setIPMreqInterface(mreq *ipMreq, ifi *net.Interface) error {
 	return errNoSuchInterface
 }
 
+func setIPMreqSourceInterface(mreqSource *ipMreqSource, ifi *net.Interface) error {
+	if ifi == nil {
+		return nil
+	}
+	ifat, err := ifi.Addrs()
+	if err != nil {
+		return err
+	}
+	for _, ifa := range ifat {
+		switch ifa := ifa.(type) {
+		case *net.IPAddr:
+			if ip := ifa.IP.To4(); ip != nil {
+				copy(mreqSource.Interface[:], ip)
+				return nil
+			}
+		case *net.IPNet:
+			if ip := ifa.IP.To4(); ip != nil {
+				copy(mreqSource.Interface[:], ip)
+				return nil
+			}
+		}
+	}
+	return errNoSuchInterface
+}
+
 func netIP4ToInterface(ip net.IP) (*net.Interface, error) {
 	ift, err := net.Interfaces()
 	if err != nil {

ipv4/sys_windows.go

@@ -59,6 +59,8 @@ var (
 		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_HDRINCL, Len: 4}},
 		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_ADD_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
 		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_DROP_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
+		ssoJoinSourceGroup:    {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_ADD_SOURCE_MEMBERSHIP, Len: sizeofIPMreqSource}, typ: ssoTypeIPMreqSource},
+		ssoLeaveSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_DROP_SOURCE_MEMBERSHIP, Len: sizeofIPMreqSource}, typ: ssoTypeIPMreqSource},
 	}
 )