From 9c39e6dccced35856719935743bb75c14f8ead56 Mon Sep 17 00:00:00 2001
From: Mikael Magnusson <mikma@users.sourceforge.net>
Date: Mon, 27 Feb 2023 23:29:04 +0100
Subject: WIP: use first ULA address as DHCPv6 source address

---
 tunnel/tools/libwg-go/dhcp.go    | 12 ++--------
 tunnel/tools/libwg-go/service.go | 48 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 11 deletions(-)

(limited to 'tunnel/tools')

diff --git a/tunnel/tools/libwg-go/dhcp.go b/tunnel/tools/libwg-go/dhcp.go
index 83a8c865..f6f25739 100644
--- a/tunnel/tools/libwg-go/dhcp.go
+++ b/tunnel/tools/libwg-go/dhcp.go
@@ -85,7 +85,7 @@ func isRelayMessageType(t dhcpv6.MessageType, tt ...dhcpv6.MessageType) nclient6
 // func New() *dhcp {
 // }
 
-func RunDhcp(ctx context.Context) ([]*gen.Lease, error) {
+func RunDhcp(ctx context.Context, laddr, raddr netip.Addr) ([]*gen.Lease, error) {
         d := &dhcp{}
         
         d.linkAddr = net.ParseIP("fe80::101")
@@ -95,25 +95,17 @@ func RunDhcp(ctx context.Context) ([]*gen.Lease, error) {
 	d.fqdn = hostName + ".m7n.se"
         d.hwAddr = []byte{41, 42, 43, 44, 45, 46}
 
-        laddr, err := netip.ParseAddr("fd1c:a56b:a0d7:1260::101")
-        if err != nil {
-                return nil, err
-        }
 
         src := net.UDPAddr{IP: laddr.AsSlice(),
                 Port: 0,        // Use non-restrict UDP source port
         }
 
-        raddr, err := netip.ParseAddr("fd1c:a56b:a0d7:1260::1")
-        if err != nil {
-                return nil, err
-        }
 
         d.serverAddr = net.UDPAddr{IP: raddr.AsSlice(),
                 Port: 547,
         }
 
-        err = d.Start(&src)
+        err := d.Start(&src)
         if err != nil {
                 return nil, err
         }
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{
-- 
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