disco: use key.NodePublic instead of tailcfg.NodeKey.

Updates #3206

Signed-off-by: David Anderson <danderson@tailscale.com>

disco/disco.go

@@ -25,8 +25,9 @@ import (
 	"fmt"
 	"net"
 
+	"go4.org/mem"
 	"inet.af/netaddr"
-	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 )
 
 // Magic is the 6 byte header of all discovery messages.
@@ -115,19 +116,19 @@ type Ping struct {
 	// It shouldn't be trusted by itself, but can be combined with
 	// netmap data to reduce the discokey:nodekey relation from 1:N to
 	// 1:1.
-	NodeKey tailcfg.NodeKey
+	NodeKey key.NodePublic
 }
 
 func (m *Ping) AppendMarshal(b []byte) []byte {
 	dataLen := 12
 	hasKey := !m.NodeKey.IsZero()
 	if hasKey {
-		dataLen += len(m.NodeKey)
+		dataLen += m.NodeKey.RawLen()
 	}
 	ret, d := appendMsgHeader(b, TypePing, v0, dataLen)
 	n := copy(d, m.TxID[:])
 	if hasKey {
-		copy(d[n:], m.NodeKey[:])
+		m.NodeKey.AppendTo(d[:n])
 	}
 	return ret
 }
@@ -138,8 +139,10 @@ func parsePing(ver uint8, p []byte) (m *Ping, err error) {
 	}
 	m = new(Ping)
 	p = p[copy(m.TxID[:], p):]
-	if len(p) >= len(m.NodeKey) {
-		copy(m.NodeKey[:], p)
+	// Deliberately lax on longer-than-expected messages, for future
+	// compatibility.
+	if len(p) >= m.NodeKey.RawLen() {
+		m.NodeKey = key.NodePublicFromRaw32(mem.B(p[:m.NodeKey.RawLen()]))
 	}
 	return m, nil
 }

disco/disco_test.go

@@ -10,8 +10,9 @@ import (
 	"strings"
 	"testing"
 
+	"go4.org/mem"
 	"inet.af/netaddr"
-	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 )
 
 func TestMarshalAndParse(t *testing.T) {
@@ -30,13 +31,8 @@ func TestMarshalAndParse(t *testing.T) {
 		{
 			name: "ping_with_nodekey_src",
 			m: &Ping{
-				TxID: [12]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12},
-				NodeKey: tailcfg.NodeKey{
-					1:  1,
-					2:  2,
-					30: 30,
-					31: 31,
-				},
+				TxID:    [12]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12},
+				NodeKey: key.NodePublicFromRaw32(mem.B([]byte{1: 1, 2: 2, 30: 30, 31: 31})),
 			},
 			want: "01 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 00 01 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1e 1f",
 		},

wgengine/magicsock/magicsock.go

@@ -1936,8 +1936,8 @@ func (c *Conn) unambiguousNodeKeyOfPingLocked(dm *disco.Ping, dk key.DiscoPublic
 
 	// Pings after 1.16.0 contains its node source. See if it maps back.
 	if !dm.NodeKey.IsZero() {
-		if ep, ok := c.peerMap.endpointForNodeKey(dm.NodeKey); ok && ep.discoKey == dk {
-			return dm.NodeKey, true
+		if ep, ok := c.peerMap.endpointForNodeKey(dm.NodeKey.AsNodeKey()); ok && ep.discoKey == dk {
+			return dm.NodeKey.AsNodeKey(), true
 		}
 	}
 
@@ -3507,7 +3507,7 @@ func (de *endpoint) sendDiscoPing(ep netaddr.IPPort, txid stun.TxID, logLevel di
 	selfPubKey, _ := de.c.publicKeyAtomic.Load().(tailcfg.NodeKey)
 	sent, _ := de.sendDiscoMessage(ep, &disco.Ping{
 		TxID:    [12]byte(txid),
-		NodeKey: selfPubKey,
+		NodeKey: selfPubKey.AsNodePublic(),
 	}, logLevel)
 	if !sent {
 		de.forgetPing(txid)