1 files changed, 192 insertions, 0 deletions
diff --git a/tunnel/tools/libwg-go/dhcp.go b/tunnel/tools/libwg-go/dhcp.go
new file mode 100644
index 00000000..b7919151
--- /dev/null
+++ b/tunnel/tools/libwg-go/dhcp.go
@@ -0,0 +1,192 @@
+package main
+
+import (
+        "context"
+        "net"
+        "net/netip"
+        "time"
+
+        "github.com/insomniacslk/dhcp/dhcpv4"
+        "github.com/insomniacslk/dhcp/dhcpv6"
+        "github.com/insomniacslk/dhcp/dhcpv6/nclient6"
+        "github.com/insomniacslk/dhcp/iana"
+
+	gen "golang.zx2c4.com/wireguard/android/gen"
+)
+
+const (
+        ENABLE_PD = true
+)
+
+type dhcp struct {
+        fqdn string
+        hwAddr net.HardwareAddr
+        conn *net.UDPConn
+        serverAddr net.UDPAddr
+        client *nclient6.Client
+        linkAddr net.IP
+        peerAddr net.IP
+}
+
+func newClientIDOpt(duid dhcpv6.DUID) dhcpv4.Option {
+	iaid := []byte{0, 0, 0, 3}
+	ident := []byte{255}                     // Type IAID+DUID
+	ident = append(ident, iaid...)           // IAID
+	ident = append(ident, duid.ToBytes()...) // DUID
+	return dhcpv4.OptClientIdentifier(ident)
+}
+
+func getDuid(hwAddr net.HardwareAddr) dhcpv6.DUID {
+	duid := &dhcpv6.DUIDLLT{
+		HWType:        iana.HWTypeEthernet,
+		Time:          uint32(time.Now().Unix()),
+		LinkLayerAddr: hwAddr,
+	}
+
+        return duid
+}
+
+func (d *dhcp) encapSendAndRead(ctx context.Context, msg *dhcpv6.Message, match nclient6.Matcher) (*dhcpv6.Message, error) {
+	packet, err := dhcpv6.EncapsulateRelay(msg, dhcpv6.MessageTypeRelayForward, d.linkAddr, d.peerAddr)
+	if err != nil {
+		return nil, err
+	}
+
+        relay, err := d.client.SendAndReadRelay(ctx, &d.serverAddr, packet, match)
+	if err != nil {
+		return nil, err
+	}
+
+        inner, err := relay.GetInnerMessage()
+        if err != nil {
+                return nil, err
+        }
+
+        return inner, nil
+}
+
+// isRelayMessageType returns a matcher that checks for the message type.
+func isRelayMessageType(t dhcpv6.MessageType, tt ...dhcpv6.MessageType) nclient6.Matcher {
+	return func(p dhcpv6.DHCPv6) bool {
+                inner, err := p.GetInnerMessage()
+                if err != nil {
+                        return false
+                }
+		if inner.Type() == t {
+			return true
+		}
+		for _, mt := range tt {
+			if inner.Type() == mt {
+				return true
+			}
+		}
+		return false
+	}
+}
+
+// func New() *dhcp {
+// }
+
+func RunDhcp(ctx context.Context, laddr, raddr netip.Addr) ([]*gen.Lease, error) {
+        d := &dhcp{}
+        
+        d.linkAddr = net.ParseIP("fe80::101")
+	d.peerAddr = net.ParseIP("::1")
+
+        // TODO generate hostname and hwAddr from public key
+	hostName := "foobar"
+	d.fqdn = hostName + ".m7n.se"
+        d.hwAddr = []byte{41, 42, 43, 44, 45, 46}
+
+
+        src := net.UDPAddr{IP: laddr.AsSlice(),
+                Port: 0,        // Use non-restrict UDP source port
+        }
+
+
+        d.serverAddr = net.UDPAddr{IP: raddr.AsSlice(),
+                Port: 547,
+        }
+
+        err := d.Start(&src)
+        if err != nil {
+                return nil, err
+        }
+
+        defer d.Close()
+
+        reply, err := d.ObtainLease(ctx) // Use reply
+        if err != nil {
+                return nil, err
+        }
+
+        return getAddressesFromReply(reply), nil
+}
+
+func getAddressesFromReply(reply *dhcpv6.Message) []*gen.Lease{
+        var leases []*gen.Lease = make([]*gen.Lease, 0, 4)
+
+        if opt := reply.GetOneOption(dhcpv6.OptionIANA); opt != nil {
+                iana := opt.(*dhcpv6.OptIANA)
+                ianaOpts := iana.Options.Get(dhcpv6.OptionIAAddr)
+
+                for _, opt := range ianaOpts {
+                        addr :=opt.(*dhcpv6.OptIAAddress).IPv6Addr
+                        lease := &gen.Lease{
+                                Address: &gen.InetAddress{
+                                        Address: addr,
+                                },
+                                // PreferredLifetime: ,
+                                // ValidLifetime: ,
+                        }
+                        leases = append(leases, lease)
+                }
+        }
+
+        return leases
+}
+
+func (d *dhcp) Start(localAddr *net.UDPAddr) error {
+        conn, err := net.ListenUDP("udp6", localAddr)
+	if err != nil {
+                return err
+        }
+        
+	d.client, err = nclient6.NewWithConn(conn, d.hwAddr, nclient6.WithDebugLogger())
+	return err
+}
+
+func (d *dhcp) Close() error {
+        err := d.client.Close()
+
+        d.client = nil
+        return err
+}
+
+func (d *dhcp) ObtainLease(ctx context.Context) (*dhcpv6.Message, error){
+        duidOpt := dhcpv6.WithClientID(getDuid(d.hwAddr))
+	fqdnOpt := dhcpv6.WithFQDN(0x1, d.fqdn)
+
+        solicit, err := dhcpv6.NewSolicit(d.hwAddr, duidOpt, fqdnOpt, dhcpv6.WithRapidCommit)
+        if err != nil {
+                return nil, err
+        }
+
+        msg, err := d.encapSendAndRead(ctx, solicit, isRelayMessageType(dhcpv6.MessageTypeReply, dhcpv6.MessageTypeAdvertise))
+        if err != nil {
+                return nil, err
+        }
+
+        if msg.Type() == dhcpv6.MessageTypeReply {
+		// We got RapidCommitted.
+		return msg, nil
+        }
+
+        // We didn't get RapidCommitted. Request regular lease.
+        req, err := dhcpv6.NewRequestFromAdvertise(msg, fqdnOpt)
+        if err != nil {
+                return nil, err
+        }
+
+        return d.encapSendAndRead(ctx, req, nil)
+}