tailcfg, controlclient: add DisplayName field to tailcfg.Node and populate it from controlclient (#1191)

Signed-off-by: Sonia Appasamy <sonia@tailscale.com>

cmd/tailscaled/depaware.txt

@@ -113,7 +113,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/strbuilder                               from tailscale.com/net/packet
         tailscale.com/types/structs                                  from tailscale.com/control/controlclient+
         tailscale.com/types/wgkey                                    from tailscale.com/control/controlclient+
-        tailscale.com/util/dnsname                                   from tailscale.com/wgengine/tsdns
+        tailscale.com/util/dnsname                                   from tailscale.com/wgengine/tsdns+
   LW    tailscale.com/util/endian                                    from tailscale.com/net/netns+
         tailscale.com/util/lineread                                  from tailscale.com/control/controlclient+
         tailscale.com/util/pidowner                                  from tailscale.com/ipn/ipnserver

control/controlclient/direct.go

@@ -775,6 +775,7 @@ func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, cb func(*Netw
 			MachineKey:      machinePubKey,
 			Expiry:          resp.Node.KeyExpiry,
 			Name:            resp.Node.Name,
+			DisplayName:     resp.Node.DisplayName,
 			Addresses:       resp.Node.Addresses,
 			Peers:           resp.Peers,
 			LocalPort:       localPort,
@@ -799,6 +800,9 @@ func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, cb func(*Netw
 		}
 		addUserProfile(nm.User)
 		for _, peer := range resp.Peers {
+			if peer.DisplayName == "" {
+				peer.DisplayName = peer.DefaultDisplayName()
+			}
 			if !peer.Sharer.IsZero() {
 				if c.keepSharerAndUserSplit {
 					addUserProfile(peer.Sharer)
@@ -808,6 +812,9 @@ func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, cb func(*Netw
 			}
 			addUserProfile(peer.User)
 		}
+		if resp.Node.DisplayName == "" {
+			nm.DisplayName = resp.Node.DefaultDisplayName()
+		}
 		if resp.Node.MachineAuthorized {
 			nm.MachineStatus = tailcfg.MachineAuthorized
 		} else {

control/controlclient/netmap.go

@@ -29,6 +29,8 @@ type NetworkMap struct {
 	Expiry     time.Time
 	// Name is the DNS name assigned to this node.
 	Name string
+	// DisplayName is the title to show for the node in client UIs.
+	DisplayName   string
 	Addresses     []netaddr.IPPrefix
 	LocalPort     uint16 // used for debugging
 	MachineStatus tailcfg.MachineStatus

tailcfg/tailcfg.go

@@ -20,6 +20,7 @@ import (
 	"tailscale.com/types/key"
 	"tailscale.com/types/opt"
 	"tailscale.com/types/structs"
+	"tailscale.com/util/dnsname"
 )
 
 // CurrentMapRequestVersion is the current MapRequest.Version value.
@@ -160,6 +161,12 @@ type Node struct {
 	StableID StableNodeID
 	Name     string // DNS
 
+	// DisplayName is the title to show for the node in client
+	// UIs. This field is assigned by default in controlclient,
+	// but can be overriden by providing this field non-empty
+	// in a MapResponse.
+	DisplayName string `json:",omitempty"`
+
 	// User is the user who created the node. If ACL tags are in
 	// use for the node then it doesn't reflect the ACL identity
 	// that the node is running as.
@@ -185,6 +192,21 @@ type Node struct {
 	MachineAuthorized bool `json:",omitempty"` // TODO(crawshaw): replace with MachineStatus
 }
 
+// DefaultDisplayName returns a value suitable
+// for using as the default value for n.DisplayName.
+func (n *Node) DefaultDisplayName() string {
+	if n.Name != "" {
+		// Use the Magic DNS prefix as the default display name.
+		return dnsname.ToBaseName(n.Name)
+	}
+	if n.Hostinfo.Hostname != "" {
+		// When no Magic DNS name is present, use the hostname.
+		return n.Hostinfo.Hostname
+	}
+	// When we've exhausted all other name options, use the node's ID.
+	return n.ID.String()
+}
+
 type MachineStatus int
 
 const (
@@ -796,6 +818,7 @@ func (n *Node) Equal(n2 *Node) bool {
 		n.ID == n2.ID &&
 		n.StableID == n2.StableID &&
 		n.Name == n2.Name &&
+		n.DisplayName == n2.DisplayName &&
 		n.User == n2.User &&
 		n.Sharer == n2.Sharer &&
 		n.Key == n2.Key &&

tailcfg/tailcfg_clone.go

@@ -64,6 +64,7 @@ var _NodeNeedsRegeneration = Node(struct {
 	ID                NodeID
 	StableID          StableNodeID
 	Name              string
+	DisplayName       string
 	User              UserID
 	Sharer            UserID
 	Key               NodeKey

tailcfg/tailcfg_test.go

@@ -189,7 +189,7 @@ func TestHostinfoEqual(t *testing.T) {
 
 func TestNodeEqual(t *testing.T) {
 	nodeHandles := []string{
-		"ID", "StableID", "Name", "User", "Sharer",
+		"ID", "StableID", "Name", "DisplayName", "User", "Sharer",
 		"Key", "KeyExpiry", "Machine", "DiscoKey",
 		"Addresses", "AllowedIPs", "Endpoints", "DERP", "Hostinfo",
 		"Created", "LastSeen", "KeepAlive", "MachineAuthorized",

util/dnsname/dnsname.go

@@ -17,3 +17,11 @@ func HasSuffix(name, suffix string) bool {
 	nameBase := strings.TrimSuffix(name, suffix)
 	return len(nameBase) < len(name) && strings.HasSuffix(nameBase, ".")
 }
+
+// ToBaseName removes the domain ending from a DNS name of a node.
+func ToBaseName(name string) string {
+	if i := strings.Index(name, "."); i != -1 {
+		return name[:i]
+	}
+	return name
+}

util/dnsname/dnsname_test.go

@@ -26,3 +26,21 @@ func TestHasSuffix(t *testing.T) {
 		}
 	}
 }
+
+func TestToBaseName(t *testing.T) {
+	tests := []struct {
+		name string
+		want string
+	}{
+		{"foo", "foo"},
+		{"foo.com", "foo"},
+		{"foo.example.com.beta.tailscale.net", "foo"},
+		{"computer-a.test.gmail.com.beta.tailscale.net", "computer-a"},
+	}
+	for _, tt := range tests {
+		got := ToBaseName(tt.name)
+		if got != tt.want {
+			t.Errorf("ToBaseName(%q) = %q; want %q", tt.name, got, tt.want)
+		}
+	}
+}