ipn/localapi: make whois take IP or IP:port as documented, fix capmap netstack lookup

The whois handler was documented as taking IP (e.g. 100.101.102.103)
or IP:port (e.g. usermode 127.0.0.1:1234) but that got broken at some point
and we started requiring a port always. Fix that.

Also, found in the process of adding tests: fix the CapMap lookup in
userspace mode (it was always returning the caps of 127.0.0.1 in
userspace mode). Fix and test that too.

Updates #9714

Change-Id: Ie9a59744286522fa91c4b70ebe89a1e94dbded26
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/localapi/localapi_test.go

@@ -9,11 +9,15 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"net/netip"
+	"net/url"
+	"strings"
 	"testing"
 
 	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/hostinfo"
 	"tailscale.com/ipn/ipnlocal"
+	"tailscale.com/tailcfg"
 	"tailscale.com/tstest"
 )
 
@@ -77,3 +81,68 @@ func TestSetPushDeviceToken(t *testing.T) {
 		t.Errorf("hostinfo.PushDeviceToken=%q, want %q", got, want)
 	}
 }
+
+type whoIsBackend struct {
+	whoIs    func(ipp netip.AddrPort) (n tailcfg.NodeView, u tailcfg.UserProfile, ok bool)
+	peerCaps map[netip.Addr]tailcfg.PeerCapMap
+}
+
+func (b whoIsBackend) WhoIs(ipp netip.AddrPort) (n tailcfg.NodeView, u tailcfg.UserProfile, ok bool) {
+	return b.whoIs(ipp)
+}
+
+func (b whoIsBackend) PeerCaps(ip netip.Addr) tailcfg.PeerCapMap {
+	return b.peerCaps[ip]
+}
+
+// Tests that the WhoIs handler accepts either IPs or IP:ports.
+//
+// From https://github.com/tailscale/tailscale/pull/9714 (a PR that is effectively a bug report)
+func TestWhoIsJustIP(t *testing.T) {
+	h := &Handler{
+		PermitRead: true,
+	}
+	for _, input := range []string{"100.101.102.103", "127.0.0.1:123"} {
+		rec := httptest.NewRecorder()
+		t.Run(input, func(t *testing.T) {
+			b := whoIsBackend{
+				whoIs: func(ipp netip.AddrPort) (n tailcfg.NodeView, u tailcfg.UserProfile, ok bool) {
+					if !strings.Contains(input, ":") {
+						want := netip.MustParseAddrPort("100.101.102.103:0")
+						if ipp != want {
+							t.Fatalf("backend called with %v; want %v", ipp, want)
+						}
+					}
+					return (&tailcfg.Node{
+							ID: 123,
+							Addresses: []netip.Prefix{
+								netip.MustParsePrefix("100.101.102.103/32"),
+							},
+						}).View(),
+						tailcfg.UserProfile{ID: 456, DisplayName: "foo"},
+						true
+				},
+				peerCaps: map[netip.Addr]tailcfg.PeerCapMap{
+					netip.MustParseAddr("100.101.102.103"): map[tailcfg.PeerCapability][]tailcfg.RawMessage{
+						"foo": {`"bar"`},
+					},
+				},
+			}
+			h.serveWhoIsWithBackend(rec, httptest.NewRequest("GET", "/v0/whois?addr="+url.QueryEscape(input), nil), b)
+
+			var res apitype.WhoIsResponse
+			if err := json.Unmarshal(rec.Body.Bytes(), &res); err != nil {
+				t.Fatal(err)
+			}
+			if got, want := res.Node.ID, tailcfg.NodeID(123); got != want {
+				t.Errorf("res.Node.ID=%v, want %v", got, want)
+			}
+			if got, want := res.UserProfile.DisplayName, "foo"; got != want {
+				t.Errorf("res.UserProfile.DisplayName=%q, want %q", got, want)
+			}
+			if got, want := len(res.CapMap), 1; got != want {
+				t.Errorf("capmap size=%v, want %v", got, want)
+			}
+		})
+	}
+}