all: migrate more code code to net/netip directly

Instead of going through the tailscale.com/net/netaddr transitional
wrappers.

Updates #5162

Change-Id: I3dafd1c2effa1a6caa9b7151ecf6edd1a3fda3dd
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

net/interfaces/interfaces.go

@@ -44,7 +44,8 @@ func Tailscale() ([]netip.Addr, *net.Interface, error) {
 		var tsIPs []netip.Addr
 		for _, a := range addrs {
 			if ipnet, ok := a.(*net.IPNet); ok {
-				nip, ok := netaddr.FromStdIP(ipnet.IP)
+				nip, ok := netip.AddrFromSlice(ipnet.IP)
+				nip = nip.Unmap()
 				if ok && tsaddr.IsTailscaleIP(nip) {
 					tsIPs = append(tsIPs, nip)
 				}
@@ -110,10 +111,11 @@ func LocalAddresses() (regular, loopback []netip.Addr, err error) {
 		for _, a := range addrs {
 			switch v := a.(type) {
 			case *net.IPNet:
-				ip, ok := netaddr.FromStdIP(v.IP)
+				ip, ok := netip.AddrFromSlice(v.IP)
 				if !ok {
 					continue
 				}
+				ip = ip.Unmap()
 				// TODO(apenwarr): don't special case cgNAT.
 				// In the general wireguard case, it might
 				// very well be something we can route to

net/interfaces/interfaces_windows.go

@@ -15,7 +15,6 @@ import (
 
 	"golang.org/x/sys/windows"
 	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
-	"tailscale.com/net/netaddr"
 	"tailscale.com/tsconst"
 )
 
@@ -65,11 +64,12 @@ func likelyHomeRouterIPWindows() (ret netip.Addr, ok bool) {
 			continue
 		}
 
-		ip, ok := netaddr.FromStdIP(r.NextHop.IP())
+		ip, ok := netip.AddrFromSlice(r.NextHop.IP())
 		if !ok {
 			// Not a valid gateway, so skip (won't happen though)
 			continue
 		}
+		ip = ip.Unmap()
 
 		if best == nil {
 			best = r