controlclient, tailcfg: deliver DERP addresses in a separate field

We still include them directly in the controlclient network map
just where we have been. Client plumbing we can do later.

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>

control/controlclient/netmap.go

@@ -238,19 +238,24 @@ func (nm *NetworkMap) _WireGuardConfig(uflags int, dnsOverride []wgcfg.IP, allEn
 		}
 		fmt.Fprintf(buf, "[Peer]\n")
 		fmt.Fprintf(buf, "PublicKey = %s\n", base64.StdEncoding.EncodeToString(peer.Key[:]))
-		if len(peer.Endpoints) > 0 {
-			if len(peer.Endpoints) == 1 {
-				fmt.Fprintf(buf, "Endpoint = %s", peer.Endpoints[0])
+		var endpoints []string
+		if peer.DERP != "" {
+			endpoints = append(endpoints, peer.DERP)
+		}
+		endpoints = append(endpoints, peer.Endpoints...)
+		if len(endpoints) > 0 {
+			if len(endpoints) == 1 {
+				fmt.Fprintf(buf, "Endpoint = %s", endpoints[0])
 			} else if allEndpoints {
 				// TODO(apenwarr): This mode is incompatible.
 				// Normal wireguard clients don't know how to
 				// parse it (yet?)
 				fmt.Fprintf(buf, "Endpoint = %s",
-					strings.Join(peer.Endpoints, ","))
+					strings.Join(endpoints, ","))
 			} else {
 				fmt.Fprintf(buf, "Endpoint = %s # other endpoints: %s",
-					peer.Endpoints[0],
-					strings.Join(peer.Endpoints[1:], ", "))
+					endpoints[0],
+					strings.Join(endpoints[1:], ", "))
 			}
 			buf.WriteByte('\n')
 		}

tailcfg/tailcfg.go

@@ -129,6 +129,7 @@ type Node struct {
 	Addresses  []wgcfg.CIDR // IP addresses of this Node directly
 	AllowedIPs []wgcfg.CIDR // range of IP addresses to route to this node
 	Endpoints  []string     `json:",omitempty"` // IP+port (public via STUN, and local LANs)
+	DERP       string       `json:",omitempty"` // DERP-in-IP:port ("127.3.3.40:N") endpoint
 	Hostinfo   Hostinfo
 	Created    time.Time
 	LastSeen   *time.Time `json:",omitempty"`

tailcfg/tailcfg_test.go

@@ -160,7 +160,7 @@ func TestHostinfoEqual(t *testing.T) {
 }
 
 func TestNodeEqual(t *testing.T) {
-	nodeHandles := []string{"ID", "Name", "User", "Key", "KeyExpiry", "Machine", "Addresses", "AllowedIPs", "Endpoints", "Hostinfo", "Created", "LastSeen", "MachineAuthorized"}
+	nodeHandles := []string{"ID", "Name", "User", "Key", "KeyExpiry", "Machine", "Addresses", "AllowedIPs", "Endpoints", "DERP", "Hostinfo", "Created", "LastSeen", "MachineAuthorized"}
 	if have := fieldsOf(reflect.TypeOf(Node{})); !reflect.DeepEqual(have, nodeHandles) {
 		t.Errorf("Node.Equal check might be out of sync\nfields: %q\nhandled: %q\n",
 			have, nodeHandles)