all: cleanup unused code, part 1 (#10661)

Run `staticcheck` with `U1000` to find unused code. This cleans up about
a half of it. I'll do the other half separately to keep PRs manageable.

Updates #cleanup

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>

net/packet/packet_test.go

@@ -74,18 +74,6 @@ var icmp4ReplyBuffer = []byte{
 	0x72, 0x65, 0x70, 0x6c, 0x79, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
 }
 
-var icmp4ReplyDecode = Parsed{
-	b:       icmp4ReplyBuffer,
-	subofs:  20,
-	dataofs: 24,
-	length:  len(icmp4ReplyBuffer),
-
-	IPVersion: 4,
-	IPProto:   ICMPv4,
-	Src:       mustIPPort("1.2.3.4:0"),
-	Dst:       mustIPPort("5.6.7.8:0"),
-}
-
 // ICMPv6 Router Solicitation
 var icmp6PacketBuffer = []byte{
 	0x60, 0x00, 0x00, 0x00, 0x00, 0x08, 0x3a, 0xff,
@@ -257,17 +245,6 @@ var udp4ReplyBuffer = []byte{
 	0x72, 0x65, 0x70, 0x6c, 0x79, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
 }
 
-var udp4ReplyDecode = Parsed{
-	b:       udp4ReplyBuffer,
-	subofs:  20,
-	dataofs: 28,
-	length:  len(udp4ReplyBuffer),
-
-	IPProto: UDP,
-	Src:     mustIPPort("1.2.3.4:567"),
-	Dst:     mustIPPort("5.6.7.8:123"),
-}
-
 // First TCP fragment of a packet with leading 24 bytes of 'a's
 var tcp4MediumFragmentBuffer = []byte{
 	// IP header up to checksum

net/portmapper/igd_test.go

@@ -50,9 +50,7 @@ type TestIGDOptions struct {
 type igdCounters struct {
 	numUPnPDiscoRecv     int32
 	numUPnPOtherUDPRecv  int32
-	numUPnPHTTPRecv      int32
 	numPMPRecv           int32
-	numPMPDiscoRecv      int32
 	numPCPRecv           int32
 	numPCPDiscoRecv      int32
 	numPCPMapRecv        int32

net/proxymux/mux_test.go

@@ -138,8 +138,8 @@ func mkWorld(t *testing.T) (ret *world) {
 	}
 	go httpProxy.Serve(ret.httpListener)
 
-	socksProxy := socks5.Server{}
-	go socksProxy.Serve(ret.socksListener)
+	ret.socksProxy = &socks5.Server{}
+	go ret.socksProxy.Serve(ret.socksListener)
 
 	ret.httpClient = &http.Client{
 		Transport: &http.Transport{

net/routetable/routetable.go

@@ -16,6 +16,7 @@ import (
 
 var (
 	defaultRouteIPv4 = RouteDestination{Prefix: netip.PrefixFrom(netip.IPv4Unspecified(), 0)}
+	//lint:ignore U1000 used in routetable_bsd_test.go
 	defaultRouteIPv6 = RouteDestination{Prefix: netip.PrefixFrom(netip.IPv6Unspecified(), 0)}
 )
 

net/tsaddr/tsaddr.go

@@ -37,7 +37,6 @@ func CGNATRange() netip.Prefix {
 
 var (
 	cgnatRange   oncePrefix
-	ulaRange     oncePrefix
 	tsUlaRange   oncePrefix
 	tsViaRange   oncePrefix
 	ula4To6Range oncePrefix

net/tsdial/peerapi_macios_ext.go

@@ -26,7 +26,7 @@ func peerDialControlFuncNetworkExtension(d *Dialer) func(network, address string
 	defer d.mu.Unlock()
 
 	index := -1
-	if x, ok := d.interfaceIndexLocked(d.tunName); ok {
+	if x, ok := interfaceIndexLocked(d); ok {
 		index = x
 	}
 	var lc net.ListenConfig
@@ -38,3 +38,15 @@ func peerDialControlFuncNetworkExtension(d *Dialer) func(network, address string
 		return lc.Control(network, address, c)
 	}
 }
+
+func interfaceIndexLocked(d *Dialer) (index int, ok bool) {
+	if d.netMon == nil {
+		return 0, false
+	}
+	st := d.netMon.InterfaceState()
+	iface, ok := st.Interface[d.tunName]
+	if !ok {
+		return 0, false
+	}
+	return iface.Index, true
+}

net/tsdial/tsdial.go

@@ -196,18 +196,6 @@ func (d *Dialer) closeSysConn(id int) {
 	go c.Close() // ignore the error
 }
 
-func (d *Dialer) interfaceIndexLocked(ifName string) (index int, ok bool) {
-	if d.netMon == nil {
-		return 0, false
-	}
-	st := d.netMon.InterfaceState()
-	iface, ok := st.Interface[ifName]
-	if !ok {
-		return 0, false
-	}
-	return iface.Index, true
-}
-
 // peerDialControlFunc is non-nil on platforms that require a way to
 // bind to dial out to other peers.
 var peerDialControlFunc func(*Dialer) func(network, address string, c syscall.RawConn) error

net/tstun/wrap_test.go

@@ -258,7 +258,6 @@ func TestWriteAndInject(t *testing.T) {
 	chtun, tun := newChannelTUN(t.Logf, false)
 	defer tun.Close()
 
-	const size = 2 // all payloads have this size
 	written := []string{"w0", "w1"}
 	injected := []string{"i0", "i1"}