global: use netip where possible now

There are more places where we'll need to add it later, when Go 1.18
comes out with support for it in the "net" package. Also, allowedips
still uses slices internally, which might be suboptimal.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

device/device_test.go

@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"io"
 	"math/rand"
-	"net"
 	"runtime"
 	"runtime/pprof"
 	"sync"
@@ -19,6 +18,7 @@ import (
 	"testing"
 	"time"
 
+	"golang.zx2c4.com/go118/netip"
 	"golang.zx2c4.com/wireguard/conn"
 	"golang.zx2c4.com/wireguard/conn/bindtest"
 	"golang.zx2c4.com/wireguard/tun/tuntest"
@@ -96,7 +96,7 @@ type testPair [2]testPeer
 type testPeer struct {
 	tun *tuntest.ChannelTUN
 	dev *Device
-	ip  net.IP
+	ip  netip.Addr
 }
 
 type SendDirection bool
@@ -159,7 +159,7 @@ func genTestPair(tb testing.TB, realSocket bool) (pair testPair) {
 	for i := range pair {
 		p := &pair[i]
 		p.tun = tuntest.NewChannelTUN()
-		p.ip = net.IPv4(1, 0, 0, byte(i+1))
+		p.ip = netip.AddrFrom4([4]byte{1, 0, 0, byte(i + 1)})
 		level := LogLevelVerbose
 		if _, ok := tb.(*testing.B); ok && !testing.Verbose() {
 			level = LogLevelError