WIP: use first ULA address as DHCPv6 source address

1 files changed, 47 insertions, 1 deletions

diff --git a/tunnel/tools/libwg-go/service.go b/tunnel/tools/libwg-go/service.go
index 2c688e26..38601f14 100644
--- a/tunnel/tools/libwg-go/service.go
+++ b/tunnel/tools/libwg-go/service.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"net/netip"
 //	"net/url"
 	"os"
 
@@ -256,7 +257,52 @@ func (e *LibwgServiceImpl) IpcSet(ctx context.Context, req *gen.IpcSetRequest) (
 }
 
 func (e *LibwgServiceImpl) Dhcp(ctx context.Context, req *gen.DhcpRequest) (*gen.DhcpResponse, error) {
-	leases, err := RunDhcp(ctx)
+	var relayAddr netip.Addr
+	var sourceAddr netip.Addr
+
+	source := req.GetSource()
+	if source != nil {
+		sourceAddr, _ = netip.AddrFromSlice(source.GetAddress())
+	}
+
+	if !sourceAddr.IsValid() || !sourceAddr.Is6() {
+		r := &gen.DhcpResponse{
+			Error: &gen.Error{
+				Message: fmt.Sprintf("DHCPv6 source address missing"),
+			},
+		}
+		return r, nil
+	}
+
+	relay := req.GetRelay()
+	if relay != nil {
+		relayAddr, _ = netip.AddrFromSlice(relay.GetAddress())
+	} else {
+		// Construct relay address from source prefix
+		relayRaw := source.GetAddress()[:8]
+		relayRaw = append(relayRaw, 0)
+		relayRaw = append(relayRaw, 0)
+		relayRaw = append(relayRaw, 0)
+		relayRaw = append(relayRaw, 0)
+		relayRaw = append(relayRaw, 0)
+		relayRaw = append(relayRaw, 0)
+		relayRaw = append(relayRaw, 0)
+		relayRaw = append(relayRaw, 1)
+		relayAddr, _ = netip.AddrFromSlice(relayRaw)
+	}
+
+	if !relayAddr.IsValid() || !relayAddr.Is6() {
+		r := &gen.DhcpResponse{
+			Error: &gen.Error{
+				Message: fmt.Sprintf("DHCPv6 relay address calculation failed"),
+			},
+		}
+		return r, nil
+	}
+
+	e.logger.Verbosef("RunDhcp %v %v", sourceAddr, relayAddr)
+
+	leases, err := RunDhcp(ctx, sourceAddr, relayAddr)
 	if err != nil {
 		r := &gen.DhcpResponse{
 			Error: &gen.Error{