From 761c25788562368d25e811cba93d011393e81c99 Mon Sep 17 00:00:00 2001
From: Manuel Buil <mbuil@suse.com>
Date: Fri, 12 Jan 2024 16:06:33 +0100
Subject: [PATCH] Provide support to select the interface in Windows

Signed-off-by: Manuel Buil <mbuil@suse.com>
---
 pkg/backend/vxlan/device_windows.go | 31 +++++++++++++++++++++++++++++
 pkg/backend/vxlan/vxlan_windows.go  |  1 +
 pkg/ipmatch/match.go                |  4 ++++
 3 files changed, 36 insertions(+)

diff --git a/pkg/backend/vxlan/device_windows.go b/pkg/backend/vxlan/device_windows.go
index bb48b6f9cf..732e060817 100644
--- a/pkg/backend/vxlan/device_windows.go
+++ b/pkg/backend/vxlan/device_windows.go
@@ -18,6 +18,7 @@ package vxlan
 
 import (
 	"encoding/json"
+	"fmt"
 	"time"
 
 	"github.com/Microsoft/hcsshim/hcn"
@@ -32,6 +33,7 @@ type vxlanDeviceAttrs struct {
 	name          string
 	gbp           bool
 	addressPrefix ip.IP4Net
+	interfaceName string
 }
 
 type vxlanDevice struct {
@@ -40,6 +42,10 @@ type vxlanDevice struct {
 	directRouting bool
 }
 
+type NetAdapterNameSettings struct {
+	NetworkAdapterName string `json:"NetworkAdapterName"`
+}
+
 func newVXLANDevice(devAttrs *vxlanDeviceAttrs) (*vxlanDevice, error) {
 	subnet := createSubnet(devAttrs.addressPrefix.String(), (devAttrs.addressPrefix.IP + 1).String(), "0.0.0.0/0")
 	network := &hcn.HostComputeNetwork{
@@ -80,6 +86,10 @@ func newVXLANDevice(devAttrs *vxlanDeviceAttrs) (*vxlanDevice, error) {
 
 	network.Ipams[0].Subnets[0].Policies = append(network.Ipams[0].Subnets[0].Policies, spJson)
 
+	if devAttrs.interfaceName != "" {
+		addNetAdapterName(network, devAttrs.interfaceName)
+	}
+
 	hnsNetwork, err := ensureNetwork(network, devAttrs.addressPrefix.String())
 	if err != nil {
 		return nil, err
@@ -205,3 +215,24 @@ func createSubnet(AddressPrefix string, NextHop string, DestPrefix string) *hcn.
 		},
 	}
 }
+
+// addNetAdapterName adds a policy to the network to set the name of the network adapter
+func addNetAdapterName(network *hcn.HostComputeNetwork, netAdapterName string) error {
+	settings := NetAdapterNameSettings{
+		NetworkAdapterName: netAdapterName,
+	}
+
+	settingsJson, err := json.Marshal(settings)
+	if err != nil {
+		return fmt.Errorf("Failed to marshal settings: %w", err)
+	}
+
+	policySettings := hcn.NetworkPolicy{
+		Type:     hcn.NetAdapterName,
+		Settings: settingsJson,
+	}
+
+	network.Policies = append(network.Policies, policySettings)
+
+	return nil
+}
diff --git a/pkg/backend/vxlan/vxlan_windows.go b/pkg/backend/vxlan/vxlan_windows.go
index 321c2f9d9d..763e6d9883 100644
--- a/pkg/backend/vxlan/vxlan_windows.go
+++ b/pkg/backend/vxlan/vxlan_windows.go
@@ -148,6 +148,7 @@ func (be *VXLANBackend) RegisterNetwork(ctx context.Context, wg *sync.WaitGroup,
 		vni:           uint32(cfg.VNI),
 		name:          cfg.Name,
 		addressPrefix: lease.Subnet,
+		interfaceName: be.extIface.Iface.Name,
 	}
 
 	dev, err := newVXLANDevice(&devAttrs)
diff --git a/pkg/ipmatch/match.go b/pkg/ipmatch/match.go
index 91eca25885..a7904e56bf 100644
--- a/pkg/ipmatch/match.go
+++ b/pkg/ipmatch/match.go
@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"net"
 	"regexp"
+	"runtime"
 	"strings"
 
 	"github.com/flannel-io/flannel/pkg/backend"
@@ -198,6 +199,9 @@ func LookupExtIface(ifname string, ifregexS string, ifcanreach string, ipStack i
 			return nil, fmt.Errorf("Could not match pattern %s to any of the available network interfaces (%s)", ifregexS, strings.Join(availableFaces, ", "))
 		}
 	} else if len(ifcanreach) > 0 {
+		if runtime.GOOS == "windows" {
+			return nil, fmt.Errorf("ifcanreach is not supported on windows")
+		}
 		log.Info("Determining interface to use based on given ifcanreach: ", ifcanreach)
 		if iface, ifaceAddr, err = ip.GetInterfaceBySpecificIPRouting(net.ParseIP(ifcanreach)); err != nil {
 			return nil, fmt.Errorf("failed to get ifcanreach based interface: %s", err)