Update water go.mod references, fix some bugs in TAP mode (which should hopefully fix Windows support too)

src/tuntap/icmpv6.go

@@ -78,8 +78,9 @@ func (i *ICMPv6) Init(t *TunAdapter) {
 // Parses an incoming ICMPv6 packet. The packet provided may be either an
 // ethernet frame containing an IP packet, or the IP packet alone. This is
 // determined by whether the TUN/TAP adapter is running in TUN (layer 3) or
-// TAP (layer 2) mode.
-func (i *ICMPv6) ParsePacket(datain []byte) {
+// TAP (layer 2) mode. Returns an error condition which is nil if the ICMPv6
+// module handled the packet or contains the error if not.
+func (i *ICMPv6) ParsePacket(datain []byte) error {
 	var response []byte
 	var err error
 
@@ -91,11 +92,12 @@ func (i *ICMPv6) ParsePacket(datain []byte) {
 	}
 
 	if err != nil {
-		return
+		return err
 	}
 
 	// Write the packet to TUN/TAP
 	i.tun.iface.Write(response)
+	return nil
 }
 
 // Unwraps the ethernet headers of an incoming ICMPv6 packet and hands off
@@ -105,7 +107,7 @@ func (i *ICMPv6) ParsePacket(datain []byte) {
 func (i *ICMPv6) UnmarshalPacketL2(datain []byte) ([]byte, error) {
 	// Ignore non-IPv6 frames
 	if binary.BigEndian.Uint16(datain[12:14]) != uint16(0x86DD) {
-		return nil, nil
+		return nil, errors.New("Ignoring non-IPv6 frame")
 	}
 
 	// Hand over to ParsePacket to interpret the IPv6 packet
@@ -141,12 +143,12 @@ func (i *ICMPv6) UnmarshalPacket(datain []byte, datamac *[]byte) ([]byte, error)
 
 	// Check if the packet is IPv6
 	if ipv6Header.Version != ipv6.Version {
-		return nil, err
+		return nil, errors.New("Ignoring non-IPv6 packet")
 	}
 
 	// Check if the packet is ICMPv6
 	if ipv6Header.NextHeader != 58 {
-		return nil, err
+		return nil, errors.New("Ignoring non-ICMPv6 packet")
 	}
 
 	// Parse the ICMPv6 message contents

src/tuntap/iface.go

@@ -111,7 +111,7 @@ func (tun *TunAdapter) writer() error {
 }
 
 func (tun *TunAdapter) reader() error {
-	recvd := make([]byte, 65535)
+	recvd := make([]byte, 65535+tun_ETHER_HEADER_LENGTH)
 	for {
 		// Wait for a packet to be delivered to us through the TUN/TAP adapter
 		n, err := tun.iface.Read(recvd)
@@ -134,17 +134,22 @@ func (tun *TunAdapter) reader() error {
 			if len(recvd) <= offset {
 				continue
 			}
-			// If we detect an ICMP packet then hand it to the ICMPv6 module
-			if recvd[offset+6] == 58 {
-				// Found an ICMPv6 packet
-				b := make([]byte, n)
-				copy(b, recvd)
-				go tun.icmpv6.ParsePacket(b)
-			}
 		}
 		// Offset the buffer from now on so that we can ignore ethernet frames if
 		// they are present
-		bs := recvd[offset:]
+		bs := recvd[offset : offset+n]
+		n -= offset
+		// If we detect an ICMP packet then hand it to the ICMPv6 module
+		if bs[6] == 58 {
+			// Found an ICMPv6 packet - we need to make sure to give ICMPv6 the full
+			// Ethernet frame rather than just the IPv6 packet as this is needed for
+			// NDP to work correctly
+			if err := tun.icmpv6.ParsePacket(recvd); err == nil {
+				// We acted on the packet in the ICMPv6 module so don't forward or do
+				// anything else with it
+				continue
+			}
+		}
 		// From the IP header, work out what our source and destination addresses
 		// and node IDs are. We will need these in order to work out where to send
 		// the packet
@@ -162,7 +167,7 @@ func (tun *TunAdapter) reader() error {
 				continue
 			}
 			// Check the packet size
-			if n != 256*int(bs[4])+int(bs[5])+offset+tun_IPv6_HEADER_LENGTH {
+			if n-tun_IPv6_HEADER_LENGTH != 256*int(bs[4])+int(bs[5]) {
 				continue
 			}
 			// IPv6 address
@@ -176,7 +181,7 @@ func (tun *TunAdapter) reader() error {
 				continue
 			}
 			// Check the packet size
-			if n != 256*int(bs[2])+int(bs[3])+offset {
+			if n != 256*int(bs[2])+int(bs[3]) {
 				continue
 			}
 			// IPv4 address
@@ -185,6 +190,7 @@ func (tun *TunAdapter) reader() error {
 			copy(dstAddr[:addrlen], bs[16:])
 		} else {
 			// Unknown address length or protocol, so drop the packet and ignore it
+			tun.log.Traceln("Unknown packet type, dropping")
 			continue
 		}
 		if tun.ckr.isEnabled() && !tun.ckr.isValidSource(srcAddr, addrlen) {

src/tuntap/tun_windows.go

@@ -71,6 +71,9 @@ func (tun *TunAdapter) setup(ifname string, iftapmode bool, addr string, mtu int
 
 // Sets the MTU of the TAP adapter.
 func (tun *TunAdapter) setupMTU(mtu int) error {
+	if tun.iface == nil || tun.iface.Name() == "" {
+		return errors.New("Can't configure MTU as TAP adapter is not present")
+	}
 	// Set MTU
 	cmd := exec.Command("netsh", "interface", "ipv6", "set", "subinterface",
 		fmt.Sprintf("interface=%s", tun.iface.Name()),
@@ -88,6 +91,9 @@ func (tun *TunAdapter) setupMTU(mtu int) error {
 
 // Sets the IPv6 address of the TAP adapter.
 func (tun *TunAdapter) setupAddress(addr string) error {
+	if tun.iface == nil || tun.iface.Name() == "" {
+		return errors.New("Can't configure IPv6 address as TAP adapter is not present")
+	}
 	// Set address
 	cmd := exec.Command("netsh", "interface", "ipv6", "add", "address",
 		fmt.Sprintf("interface=%s", tun.iface.Name()),