netstack: add CreateNetTUNWithStack

Allow the caller to specify the stack to make it possible for
more complex scenarios with multiple network interfaces.

Signed-off-by: Mikael Magnusson <mikma@users.sourceforge.net>

1 files changed, 52 insertions, 16 deletions

diff --git a/tun/netstack/tun.go b/tun/netstack/tun.go
index f61cc2a..8e3ce4b 100644
--- a/tun/netstack/tun.go
+++ b/tun/netstack/tun.go
@@ -38,13 +38,22 @@ type netTun struct {
 	events         chan tun.Event
 	incomingPacket chan buffer.VectorisedView
 	mtu            int
+}
+type endpoint netTun
+type Net struct {
+	stack          *stack.Stack
+	nicID          tcpip.NICID
 	dnsServers     []net.IP
 	hasV4, hasV6   bool
 }
-type endpoint netTun
-type Net netTun
 
 func (e *endpoint) Attach(dispatcher stack.NetworkDispatcher) {
+	if dispatcher == nil {
+		(*netTun)(e).events <- tun.EventUp
+	} else {
+		(*netTun)(e).events <- tun.EventDown
+	}
+
 	e.dispatcher = dispatcher
 }
 
@@ -100,10 +109,10 @@ func (net *Net) addAddress(ip net.IP) tcpip.Error {
 			Protocol:          ipv4.ProtocolNumber,
 			AddressWithPrefix: tcpip.Address(ip4).WithPrefix(),
 		}
-		tcpipErr := net.stack.AddProtocolAddress(1, protoAddr, stack.AddressProperties{})
+		tcpipErr := net.stack.AddProtocolAddress(net.nicID, protoAddr, stack.AddressProperties{})
 		if tcpipErr == nil && !net.hasV4 {
 			net.hasV4 = true
-			net.stack.AddRoute(tcpip.Route{Destination: header.IPv4EmptySubnet, NIC: 1})
+			net.stack.AddRoute(tcpip.Route{Destination: header.IPv4EmptySubnet, NIC: net.nicID})
 		}
 		return tcpipErr
 	} else {
@@ -111,10 +120,10 @@ func (net *Net) addAddress(ip net.IP) tcpip.Error {
 			Protocol:          ipv6.ProtocolNumber,
 			AddressWithPrefix: tcpip.Address(ip).WithPrefix(),
 		}
-		tcpipErr := net.stack.AddProtocolAddress(1, protoAddr, stack.AddressProperties{})
+		tcpipErr := net.stack.AddProtocolAddress(net.nicID, protoAddr, stack.AddressProperties{})
 		if tcpipErr == nil && !net.hasV6{
 			net.hasV6 = true
-			net.stack.AddRoute(tcpip.Route{Destination: header.IPv6EmptySubnet, NIC: 1})
+			net.stack.AddRoute(tcpip.Route{Destination: header.IPv6EmptySubnet, NIC: net.nicID})
 		}
 		return tcpipErr
 	}
@@ -126,26 +135,52 @@ func CreateNetTUN(localAddresses, dnsServers []net.IP, mtu int) (tun.Device, *Ne
 		TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol, udp.NewProtocol},
 		HandleLocal:        true,
 	}
-	dev := &netTun{
-		stack:          stack.New(opts),
-		events:         make(chan tun.Event, 10),
-		incomingPacket: make(chan buffer.VectorisedView),
-		dnsServers:     dnsServers,
-		mtu:            mtu,
+	return CreateNetTUNWithStack(stack.New(opts), 1, localAddresses, dnsServers, mtu)
+}
+
+func CreateNetTUNWithStack(stack *stack.Stack, nicID tcpip.NICID, localAddresses []net.IP, dnsServers []net.IP, mtu int) (tun.Device, *Net, error) {
+	dev, ep, err := NewNetTUN(stack, mtu)
+	if err != nil {
+		return nil, nil, err
 	}
-	tcpipErr := dev.stack.CreateNIC(1, (*endpoint)(dev))
+
+	tcpipErr := stack.CreateNIC(nicID, ep)
 	if tcpipErr != nil {
 		return nil, nil, fmt.Errorf("CreateNIC: %v", tcpipErr)
 	}
+
+	tnet, err := NewNetAdapter(stack, nicID, localAddresses, dnsServers)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return dev, tnet, nil
+}
+
+func NewNetAdapter(stack *stack.Stack, nicID tcpip.NICID, localAddresses []net.IP, dnsServers []net.IP,) (*Net, error) {
+	tnet := &Net{
+		stack:		stack,
+		nicID:		nicID,
+		dnsServers:     dnsServers,
+	}
 	for _, ip := range localAddresses {
 		tcpipErr := tnet.addAddress(ip)
 		if tcpipErr != nil {
 			return nil, fmt.Errorf("addAddress(%v): %w", ip, tcpipErr)
 		}
 	}
+	return tnet, nil
+}
+
+func NewNetTUN(stack *stack.Stack, mtu int) (*netTun, *endpoint, error) {
+	dev := &netTun{
+		stack:		stack,
+		events:         make(chan tun.Event, 10),
+		incomingPacket: make(chan buffer.VectorisedView),
+		mtu:            mtu,
+	}
 
-	dev.events <- tun.EventUp
-	return dev, (*Net)(dev), nil
+	return dev, (*endpoint)(dev), nil
 }
 
 func (tun *netTun) Name() (string, error) {
@@ -190,7 +225,8 @@ func (tun *netTun) Flush() error {
 }
 
 func (tun *netTun) Close() error {
-	tun.stack.RemoveNIC(1)
+// FIXME move somewhere else
+//	tun.stack.RemoveNIC(tun.nicID)
 
 	if tun.events != nil {
 		close(tun.events)