You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: interfaces_windows.go
    path of file: ./repos/sliver/vendor/tailscale.com/net/interfaces
    
    the code of the file until where you have to start completion: // Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause

package interfaces

import (
	"log"
	"net/netip"
	"net/url"
	"strings"
	"syscall"
	"unsafe"

	"golang.org/x/sys/windows"
	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
	"tailscale.com/tsconst"
)

const (
	fallbackInterfaceMetric = uint32(0) // Used if we cannot get the actual interface metric
)

func init() {
	likelyHomeRouterIP = likelyHomeRouterIPWindows
	getPAC = getPACWindows
}

func likelyHomeRouterIPWindows() (ret netip.Addr, ok bool) {
	rs, err := winipcfg.GetIPForwardTable2(windows.AF_INET)
	if err != nil {
		log.Printf("routerIP/GetIPForwardTable2 error: %v", 
    
func getPACWindows() string {
	var res *uint16
	r, _, e := detectAutoProxyConfigURL.Call(
		winHTTP_AUTO_DETECT_TYPE_DHCP|winHTTP_AUTO_DETECT_TYPE_DNS_A,
		uintptr(unsafe.Pointer(&res)),
	)
	if r == 1 {
		if res == nil {
			log.Printf("getPACWindows: unexpected success with nil result")
			return ""
		}
		defer globalFree.Call(uintptr(unsafe.Pointer(res)))
		s := windows.UTF16PtrToString(res)
		s = strings.TrimSpace(s)
		if s == "" {
			return "" // Issue 2357: invalid URL "\n" from winhttp; ignoring
		}
		if _, err := url.Parse(s); err != nil {
			log.Printf("getPACWindows: invalid URL %q from winhttp; ignoring", s)
			return ""
		}
		return s
	}
	const (
		ERROR_WINHTTP_AUTODETECTION_FAILED = 12180
	)
	if e == syscall.Errno(ERROR_WINHTTP_AUTODETECTION_FAILED) {
		// Common case on networks without advertised PAC.
		return ""
	}
	log.Printf("getPACWindows: %T=%v", e, e) // syscall.Errno=0x....
	return ""
}