4 files changed, 118 insertions, 0 deletions
diff --git a/tun/wintun/iphlpapi/conversion_windows.go b/tun/wintun/iphlpapi/conversion_windows.go
new file mode 100644
index 0000000..a19e961
--- /dev/null
+++ b/tun/wintun/iphlpapi/conversion_windows.go
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package iphlpapi
+
+import "golang.org/x/sys/windows"
+
+//sys	convertInterfaceLUIDToGUID(interfaceLUID *uint64, interfaceGUID *windows.GUID) (ret error) = iphlpapi.ConvertInterfaceLuidToGuid
+//sys	convertInterfaceAliasToLUID(interfaceAlias *uint16, interfaceLUID *uint64) (ret error) = iphlpapi.ConvertInterfaceAliasToLuid
+
+func InterfaceGUIDFromAlias(alias string) (*windows.GUID, error) {
+	var luid uint64
+	var guid windows.GUID
+	err := convertInterfaceAliasToLUID(windows.StringToUTF16Ptr(alias), &luid)
+	if err != nil {
+		return nil, err
+	}
+	err = convertInterfaceLUIDToGUID(&luid, &guid)
+	if err != nil {
+		return nil, err
+	}
+	return &guid, nil
+}
diff --git a/tun/wintun/iphlpapi/mksyscall.go b/tun/wintun/iphlpapi/mksyscall.go
new file mode 100644
index 0000000..f2639ea
--- /dev/null
+++ b/tun/wintun/iphlpapi/mksyscall.go
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package iphlpapi
+
+//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go conversion_windows.go
diff --git a/tun/wintun/iphlpapi/zsyscall_windows.go b/tun/wintun/iphlpapi/zsyscall_windows.go
new file mode 100644
index 0000000..dc14294
--- /dev/null
+++ b/tun/wintun/iphlpapi/zsyscall_windows.go
@@ -0,0 +1,60 @@
+// Code generated by 'go generate'; DO NOT EDIT.
+
+package iphlpapi
+
+import (
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var _ unsafe.Pointer
+
+// Do the interface allocations only once for common
+// Errno values.
+const (
+	errnoERROR_IO_PENDING = 997
+)
+
+var (
+	errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return nil
+	case errnoERROR_IO_PENDING:
+		return errERROR_IO_PENDING
+	}
+	// TODO: add more here, after collecting data on the common
+	// error values see on Windows. (perhaps when running
+	// all.bat?)
+	return e
+}
+
+var (
+	modiphlpapi = windows.NewLazySystemDLL("iphlpapi.dll")
+
+	procConvertInterfaceLuidToGuid  = modiphlpapi.NewProc("ConvertInterfaceLuidToGuid")
+	procConvertInterfaceAliasToLuid = modiphlpapi.NewProc("ConvertInterfaceAliasToLuid")
+)
+
+func convertInterfaceLUIDToGUID(interfaceLUID *uint64, interfaceGUID *windows.GUID) (ret error) {
+	r0, _, _ := syscall.Syscall(procConvertInterfaceLuidToGuid.Addr(), 2, uintptr(unsafe.Pointer(interfaceLUID)), uintptr(unsafe.Pointer(interfaceGUID)), 0)
+	if r0 != 0 {
+		ret = syscall.Errno(r0)
+	}
+	return
+}
+
+func convertInterfaceAliasToLUID(interfaceAlias *uint16, interfaceLUID *uint64) (ret error) {
+	r0, _, _ := syscall.Syscall(procConvertInterfaceAliasToLuid.Addr(), 2, uintptr(unsafe.Pointer(interfaceAlias)), uintptr(unsafe.Pointer(interfaceLUID)), 0)
+	if r0 != 0 {
+		ret = syscall.Errno(r0)
+	}
+	return
+}
diff --git a/tun/wintun/wintun_windows.go b/tun/wintun/wintun_windows.go
index 81da251..f5d42eb 100644
--- a/tun/wintun/wintun_windows.go
+++ b/tun/wintun/wintun_windows.go
@@ -15,6 +15,7 @@ import (
 	"golang.org/x/sys/windows"
 	"golang.org/x/sys/windows/registry"
 
+	"golang.zx2c4.com/wireguard/tun/wintun/iphlpapi"
 	"golang.zx2c4.com/wireguard/tun/wintun/nci"
 	registryEx "golang.zx2c4.com/wireguard/tun/wintun/registry"
 	"golang.zx2c4.com/wireguard/tun/wintun/setupapi"
@@ -528,11 +529,35 @@ func (wintun *Wintun) InterfaceName() (string, error) {
 func (wintun *Wintun) SetInterfaceName(ifname string) error {
 	const maxSuffix = 1000
 	availableIfname := ifname
+setloop:
 	for i := 0; ; i++ {
 		err := nci.SetConnectionName(&wintun.cfgInstanceID, availableIfname)
 		if err == nil {
 			break
 		}
+		if err == windows.ERROR_DUP_NAME {
+			duplicateGuid, err2 := iphlpapi.InterfaceGUIDFromAlias(availableIfname)
+			if err2 == nil {
+				for j := 0; j < 1000; j++ {
+					proposal := fmt.Sprintf("%s %d", ifname, j+1)
+					if proposal == availableIfname {
+						continue
+					}
+					err2 = nci.SetConnectionName(duplicateGuid, proposal)
+					if err2 == windows.ERROR_DUP_NAME {
+						continue
+					}
+					if err2 == nil {
+						err = nci.SetConnectionName(&wintun.cfgInstanceID, availableIfname)
+						if err == nil {
+							break setloop
+						}
+					}
+					break
+				}
+			}
+		}
+
 		if i > maxSuffix || err != windows.ERROR_DUP_NAME {
 			return fmt.Errorf("NciSetConnectionName failed: %v", err)
 		}