Warp/server/internal/keyserver/keyserver_test.go

package keyserver_test

import (
	"context"
	"encoding/json"
	"errors"
	"path/filepath"
	"slices"
	"sync"
	"testing"

	"github.com/dariuszjaniak/warp/server/internal/federation"
	"github.com/dariuszjaniak/warp/server/internal/keyserver"
	"github.com/dariuszjaniak/warp/server/internal/matrix/signing"
	"github.com/dariuszjaniak/warp/server/internal/storage"
	_ "github.com/dariuszjaniak/warp/server/internal/storage/drivers"
)

const (
	alice = "@alice:warp.example"
	bob   = "@bob:warp.example"
	carol = "@carol:remote.example"
)

// --- fakes --------------------------------------------------------------------

type fakeRooms struct {
	mu      sync.Mutex
	sharing map[string][]string
}

func (f *fakeRooms) UsersSharingRooms(_ context.Context, userID string) ([]string, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	return slices.Clone(f.sharing[userID]), nil
}

// set replaces who shares a room with userID.
func (f *fakeRooms) set(userID string, users ...string) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.sharing[userID] = users
}

type fakeNotifier struct {
	mu    sync.Mutex
	woken []string
}

func (n *fakeNotifier) NotifyUsers(userIDs []string) {
	n.mu.Lock()
	defer n.mu.Unlock()
	n.woken = append(n.woken, userIDs...)
}

func (n *fakeNotifier) wasWoken(userID string) bool {
	n.mu.Lock()
	defer n.mu.Unlock()
	return slices.Contains(n.woken, userID)
}

type fakeDevices struct{ byLocalpart map[string][]storage.Device }

func (f fakeDevices) Devices(_ context.Context, localpart string) ([]storage.Device, error) {
	return f.byLocalpart[localpart], nil
}

type sentEDU struct {
	destinations []string
	edu          federation.EDU
}

type fakeOutbound struct {
	mu   sync.Mutex
	sent []sentEDU
}

func (o *fakeOutbound) Running() bool { return true }

func (o *fakeOutbound) QueueEDU(_ context.Context, destinations []string, edu federation.EDU) {
	o.mu.Lock()
	defer o.mu.Unlock()
	o.sent = append(o.sent, sentEDU{destinations: destinations, edu: edu})
}

func (o *fakeOutbound) ofType(t string) []sentEDU {
	o.mu.Lock()
	defer o.mu.Unlock()
	var out []sentEDU
	for _, s := range o.sent {
		if s.edu.Type == t {
			out = append(out, s)
		}
	}
	return out
}

type harness struct {
	keys     *keyserver.API
	store    storage.KeyStore
	rooms    *fakeRooms
	notifier *fakeNotifier
	outbound *fakeOutbound
}

func newHarness(t *testing.T, remote keyserver.Remote) harness {
	t.Helper()
	path := filepath.ToSlash(filepath.Join(t.TempDir(), "warp.db"))
	db, err := storage.Open(t.Context(), storage.Config{
		Driver:           storage.DriverSQLite,
		ConnectionString: "file:" + path + "?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)",
	}, nil)
	if err != nil {
		t.Fatalf("storage.Open: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })
	if err := db.Migrate(t.Context()); err != nil {
		t.Fatalf("Migrate: %v", err)
	}

	h := harness{store: db.Keys(), notifier: &fakeNotifier{}, outbound: &fakeOutbound{}}
	h.rooms = &fakeRooms{sharing: map[string][]string{
		alice: {alice, bob, carol},
		bob:   {alice, bob},
		carol: {alice, carol},
	}}
	h.keys, err = keyserver.New(keyserver.Options{
		ServerName: "warp.example",
		Store:      db.Keys(),
		Rooms:      h.rooms,
		Notifier:   h.notifier,
		Devices: fakeDevices{byLocalpart: map[string][]storage.Device{
			"alice": {{Localpart: "alice", ID: "D1", DisplayName: "Alice's phone"}, {Localpart: "alice", ID: "D2"}},
			"bob":   {{Localpart: "bob", ID: "B1"}},
		}},
		Remote:   remote,
		Outbound: h.outbound,
	})
	if err != nil {
		t.Fatalf("keyserver.New: %v", err)
	}
	t.Cleanup(h.keys.Close)
	return h
}

// --- keys ---------------------------------------------------------------------

// newKey makes an ed25519 key named by its own public key, which is how a
// cross-signing key is named; a device key is renamed to its device ID.
func newKey(t *testing.T) *signing.KeyPair {
	t.Helper()
	kp, err := signing.Generate("")
	if err != nil {
		t.Fatal(err)
	}
	kp.ID = kp.PublicBase64()
	return kp
}

func signed(t *testing.T, userID string, kp *signing.KeyPair, v any) json.RawMessage {
	t.Helper()
	raw, err := json.Marshal(v)
	if err != nil {
		t.Fatal(err)
	}
	out, err := signing.SignJSON(userID, kp, raw)
	if err != nil {
		t.Fatal(err)
	}
	return out
}

// device is a device's identity key pair and its signed device_keys.
func device(t *testing.T, userID, deviceID string) (*signing.KeyPair, json.RawMessage) {
	t.Helper()
	kp := newKey(t)
	pub := kp.PublicBase64()
	kp.ID = deviceID
	return kp, signed(t, userID, kp, map[string]any{
		"user_id":    userID,
		"device_id":  deviceID,
		"algorithms": []string{"m.olm.v1.curve25519-aes-sha2", "m.megolm.v1.aes-sha2"},
		"keys": map[string]string{
			"ed25519:" + deviceID:    pub,
			"curve25519:" + deviceID: "curve-" + deviceID,
		},
	})
}

func crossSigningKey(userID, usage string, kp *signing.KeyPair) map[string]any {
	return map[string]any{
		"user_id": userID,
		"usage":   []string{usage},
		"keys":    map[string]string{"ed25519:" + kp.PublicBase64(): kp.PublicBase64()},
	}
}

// crossSigning is a user's three cross-signing keys, uploaded.
type crossSigning struct {
	master, selfSigning, userSigning *signing.KeyPair
	req                              keyserver.CrossSigningRequest
}

func newCrossSigning(t *testing.T, userID string) crossSigning {
	t.Helper()
	cs := crossSigning{master: newKey(t), selfSigning: newKey(t), userSigning: newKey(t)}
	cs.req = keyserver.CrossSigningRequest{
		MasterKey:      signed(t, userID, newKey(t), crossSigningKey(userID, "master", cs.master)),
		SelfSigningKey: signed(t, userID, cs.master, crossSigningKey(userID, "self_signing", cs.selfSigning)),
		UserSigningKey: signed(t, userID, cs.master, crossSigningKey(userID, "user_signing", cs.userSigning)),
	}
	// The master key's own signature above is by a throwaway key, which
	// the server does not check; what it checks is that the master key
	// signed the other two.
	raw, _ := json.Marshal(crossSigningKey(userID, "master", cs.master))
	cs.req.MasterKey = raw
	return cs
}

func decodeObject(t *testing.T, raw json.RawMessage) map[string]any {
	t.Helper()
	var out map[string]any
	if err := json.Unmarshal(raw, &out); err != nil {
		t.Fatalf("decode %s: %v", raw, err)
	}
	return out
}

func signaturesBy(t *testing.T, raw json.RawMessage, userID string) map[string]any {
	t.Helper()
	sigs, _ := decodeObject(t, raw)["signatures"].(map[string]any)
	out, _ := sigs[userID].(map[string]any)
	return out
}

// --- tests --------------------------------------------------------------------

func TestUploadAndQueryDeviceKeys(t *testing.T) {
	ctx := t.Context()
	h := newHarness(t, nil)
	_, d1 := device(t, alice, "D1")

	counts, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{
		DeviceKeys: d1,
		OneTimeKeys: map[string]json.RawMessage{
			"signed_curve25519:AAA": json.RawMessage(`{"key":"a"}`),
			"signed_curve25519:BBB": json.RawMessage(`{"key":"b"}`),
		},
		FallbackKeys: map[string]json.RawMessage{
			"signed_curve25519:FFF": json.RawMessage(`{"key":"f","fallback":true}`),
		},
	})
	if err != nil {
		t.Fatalf("UploadKeys: %v", err)
	}
	if counts["signed_curve25519"] != 2 {
		t.Errorf("one_time_key_counts = %v, want 2 signed_curve25519", counts)
	}

	// Everybody sharing a room hears of it: the local ones are woken, the
	// remote server gets an m.device_list_update with the keys in it.
	if !h.notifier.wasWoken(bob) {
		t.Error("a user sharing a room was not woken")
	}
	updates := h.outbound.ofType(federation.EDUDeviceListUp)
	if len(updates) != 1 || !slices.Equal(updates[0].destinations, []string{"remote.example"}) {
		t.Fatalf("device list EDUs = %+v, want one to remote.example", updates)
	}
	var content federation.DeviceListUpdateContent
	_ = json.Unmarshal(updates[0].edu.Content, &content)
	if content.UserID != alice || content.DeviceID != "D1" || content.Deleted || len(content.Keys) == 0 || content.StreamID == 0 {
		t.Errorf("EDU content = %+v", content)
	}

	resp, err := h.keys.QueryKeys(ctx, bob, keyserver.QueryRequest{DeviceKeys: map[string][]string{alice: nil}})
	if err != nil {
		t.Fatalf("QueryKeys: %v", err)
	}
	got, ok := resp.DeviceKeys[alice]["D1"]
	if !ok {
		t.Fatalf("query did not return D1: %+v", resp.DeviceKeys)
	}
	unsigned, _ := decodeObject(t, got)["unsigned"].(map[string]any)
	if unsigned["device_display_name"] != "Alice's phone" {
		t.Errorf("unsigned = %v, want the device's display name", unsigned)
	}
	if _, err := signing.SigningBytes(got); err != nil {
		t.Errorf("queried keys are not a signed object: %v", err)
	}

	// Somebody else's device, or keys naming another device, are refused.
	_, other := device(t, alice, "D2")
	if _, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{DeviceKeys: other}); !errors.Is(err, keyserver.ErrInvalidParam) {
		t.Errorf("keys for another device = %v, want ErrInvalidParam", err)
	}
	_, bobs := device(t, bob, "D1")
	if _, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{DeviceKeys: bobs}); !errors.Is(err, keyserver.ErrInvalidParam) {
		t.Errorf("keys for another user = %v, want ErrInvalidParam", err)
	}

	// The same one-time key again is fine, encoded differently or not; a
	// different key under its ID is not.
	if _, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{
		OneTimeKeys: map[string]json.RawMessage{"signed_curve25519:AAA": json.RawMessage(`{ "key" : "a" }`)},
	}); err != nil {
		t.Errorf("re-uploading the same key: %v", err)
	}
	if _, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{
		OneTimeKeys: map[string]json.RawMessage{"signed_curve25519:AAA": json.RawMessage(`{"key":"z"}`)},
	}); !errors.Is(err, keyserver.ErrKeyConflict) {
		t.Errorf("a conflicting key = %v, want ErrKeyConflict", err)
	}
	if _, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{
		OneTimeKeys: map[string]json.RawMessage{"no-algorithm": json.RawMessage(`"x"`)},
	}); !errors.Is(err, keyserver.ErrInvalidParam) {
		t.Errorf("a key ID with no algorithm = %v, want ErrInvalidParam", err)
	}
}

func TestClaimKeys(t *testing.T) {
	ctx := t.Context()
	h := newHarness(t, nil)
	_, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{
		OneTimeKeys:  map[string]json.RawMessage{"signed_curve25519:AAA": json.RawMessage(`{"key":"a"}`)},
		FallbackKeys: map[string]json.RawMessage{"signed_curve25519:FFF": json.RawMessage(`{"key":"f"}`)},
	})
	if err != nil {
		t.Fatal(err)
	}

	claim := func() keyserver.ClaimResponse {
		t.Helper()
		resp, err := h.keys.ClaimKeys(ctx, keyserver.ClaimRequest{OneTimeKeys: map[string]map[string]string{
			alice: {"D1": "signed_curve25519", "D2": "signed_curve25519"},
			carol: {"C1": "signed_curve25519"},
		}})
		if err != nil {
			t.Fatalf("ClaimKeys: %v", err)
		}
		return resp
	}

	first := claim()
	if _, ok := first.OneTimeKeys[alice]["D1"]["signed_curve25519:AAA"]; !ok {
		t.Errorf("first claim = %v, want the one-time key", first.OneTimeKeys)
	}
	if _, ok := first.OneTimeKeys[alice]["D2"]; ok {
		t.Error("a device with no keys was given one")
	}
	if _, ok := first.Failures["remote.example"]; !ok {
		t.Errorf("a server that cannot be asked is not a failure: %v", first.Failures)
	}

	second := claim()
	if _, ok := second.OneTimeKeys[alice]["D1"]["signed_curve25519:FFF"]; !ok {
		t.Errorf("second claim = %v, want the fallback key", second.OneTimeKeys)
	}
	if types, _ := h.keys.UnusedFallbackKeyTypes(ctx, alice, "D1"); len(types) != 0 {
		t.Errorf("a claimed fallback key is still unused: %v", types)
	}
}

// fakeRemote answers for remote.example.
type fakeRemote struct{}

func (fakeRemote) QueryUserKeys(_ context.Context, _ string, req federation.UserKeysQueryRequest) (federation.UserKeysQueryResponse, error) {
	return federation.UserKeysQueryResponse{
		DeviceKeys: map[string]map[string]json.RawMessage{
			dave:                  {"V1": json.RawMessage(`{"device_id":"V1"}`)},
			"@mallory:other.test": {"M1": json.RawMessage(`{}`)},
		},
	}, nil
}

func (fakeRemote) ClaimUserKeys(context.Context, string, federation.UserKeysClaimRequest) (federation.UserKeysClaimResponse, error) {
	return federation.UserKeysClaimResponse{}, errors.New("unreachable")
}

func (fakeRemote) UserDevices(context.Context, string, string) (federation.UserDevicesResponse, error) {
	return federation.UserDevicesResponse{}, errors.New("unreachable")
}

// dave is a remote user nobody here shares a room with.
const dave = "@dave:remote.example"

func TestQueryAsksOtherServers(t *testing.T) {
	h := newHarness(t, fakeRemote{})
	resp, err := h.keys.QueryKeys(t.Context(), alice, keyserver.QueryRequest{DeviceKeys: map[string][]string{dave: nil}})
	if err != nil {
		t.Fatal(err)
	}
	if _, ok := resp.DeviceKeys[dave]["V1"]; !ok {
		t.Errorf("remote keys = %v", resp.DeviceKeys)
	}
	if _, ok := resp.DeviceKeys["@mallory:other.test"]; ok {
		t.Error("a server's answer about a user it was not asked about was passed on")
	}

	claimed, _ := h.keys.ClaimKeys(t.Context(), keyserver.ClaimRequest{OneTimeKeys: map[string]map[string]string{carol: {"C1": "signed_curve25519"}}})
	if failure, ok := claimed.Failures["remote.example"].(map[string]any); !ok || failure["status"] != 503 {
		t.Errorf("failures = %v, want a 503 for remote.example", claimed.Failures)
	}
}

func TestCrossSigning(t *testing.T) {
	ctx := t.Context()
	h := newHarness(t, nil)
	cs := newCrossSigning(t, alice)

	if needs, err := h.keys.CrossSigningNeedsAuth(ctx, alice, cs.req); err != nil || needs {
		t.Fatalf("a first upload needs auth = %v, %v; want false", needs, err)
	}
	if err := h.keys.UploadCrossSigningKeys(ctx, alice, cs.req); err != nil {
		t.Fatalf("UploadCrossSigningKeys: %v", err)
	}
	if updates := h.outbound.ofType(federation.EDUSigningKeys); len(updates) != 1 {
		t.Errorf("signing key EDUs = %d, want 1", len(updates))
	}

	// The same keys again need no password; a new master key does.
	if needs, _ := h.keys.CrossSigningNeedsAuth(ctx, alice, cs.req); needs {
		t.Error("re-uploading the same keys needs auth")
	}
	replacement := newCrossSigning(t, alice)
	if needs, _ := h.keys.CrossSigningNeedsAuth(ctx, alice, replacement.req); !needs {
		t.Error("replacing the master key needs no auth")
	}

	// The user-signing key is only shown to its owner.
	mine, _ := h.keys.QueryKeys(ctx, alice, keyserver.QueryRequest{DeviceKeys: map[string][]string{alice: nil}})
	theirs, _ := h.keys.QueryKeys(ctx, bob, keyserver.QueryRequest{DeviceKeys: map[string][]string{alice: nil}})
	if _, ok := mine.UserSigningKeys[alice]; !ok {
		t.Error("the owner does not see their user-signing key")
	}
	if _, ok := theirs.UserSigningKeys[alice]; ok {
		t.Error("another user sees the user-signing key")
	}
	if _, ok := theirs.MasterKeys[alice]; !ok {
		t.Error("another user does not see the master key")
	}
	if _, ok := theirs.SelfSigningKeys[alice]; !ok {
		t.Error("another user does not see the self-signing key")
	}

	// A self-signing key the master key did not sign is refused.
	forged := keyserver.CrossSigningRequest{
		SelfSigningKey: signed(t, alice, newKey(t), crossSigningKey(alice, "self_signing", newKey(t))),
	}
	if err := h.keys.UploadCrossSigningKeys(ctx, alice, forged); !errors.Is(err, keyserver.ErrInvalidSignature) {
		t.Errorf("a self-signing key not signed by the master = %v, want ErrInvalidSignature", err)
	}
	wrongUsage := keyserver.CrossSigningRequest{
		SelfSigningKey: signed(t, alice, cs.master, crossSigningKey(alice, "user_signing", newKey(t))),
	}
	if err := h.keys.UploadCrossSigningKeys(ctx, alice, wrongUsage); !errors.Is(err, keyserver.ErrInvalidParam) {
		t.Errorf("a key with the wrong usage = %v, want ErrInvalidParam", err)
	}

	// A new master key on its own drops the keys the old one signed.
	if err := h.keys.UploadCrossSigningKeys(ctx, alice, keyserver.CrossSigningRequest{MasterKey: replacement.req.MasterKey}); err != nil {
		t.Fatalf("replacing the master key: %v", err)
	}
	after, _ := h.keys.QueryKeys(ctx, alice, keyserver.QueryRequest{DeviceKeys: map[string][]string{alice: nil}})
	if _, ok := after.SelfSigningKeys[alice]; ok {
		t.Error("the old self-signing key survived a new master key")
	}

	// And nothing but a master key needs one first.
	if err := h.keys.UploadCrossSigningKeys(ctx, bob, keyserver.CrossSigningRequest{
		SelfSigningKey: signed(t, bob, newKey(t), crossSigningKey(bob, "self_signing", newKey(t))),
	}); !errors.Is(err, keyserver.ErrMissingParam) {
		t.Errorf("a self-signing key with no master = %v, want ErrMissingParam", err)
	}
}

func TestSignatureUploads(t *testing.T) {
	ctx := t.Context()
	h := newHarness(t, nil)

	deviceKey, d1 := device(t, alice, "D1")
	if _, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{DeviceKeys: d1}); err != nil {
		t.Fatal(err)
	}
	cs := newCrossSigning(t, alice)
	if err := h.keys.UploadCrossSigningKeys(ctx, alice, cs.req); err != nil {
		t.Fatal(err)
	}
	bobs := newCrossSigning(t, bob)
	if err := h.keys.UploadCrossSigningKeys(ctx, bob, bobs.req); err != nil {
		t.Fatal(err)
	}

	var stripped map[string]any
	_ = json.Unmarshal(d1, &stripped)
	delete(stripped, "signatures")

	masterPub := cs.master.PublicBase64()
	failures, err := h.keys.UploadSignatures(ctx, alice, map[string]map[string]json.RawMessage{
		alice: {
			// The device, by the self-signing key.
			"D1": signed(t, alice, cs.selfSigning, stripped),
			// The master key, by the device.
			masterPub: signed(t, alice, deviceKey, crossSigningKey(alice, "master", cs.master)),
		},
		// Bob's master key, by Alice's user-signing key.
		bob: {bobs.master.PublicBase64(): signed(t, alice, cs.userSigning, crossSigningKey(bob, "master", bobs.master))},
	})
	if err != nil || len(failures) != 0 {
		t.Fatalf("UploadSignatures = %v, %v", failures, err)
	}

	resp, _ := h.keys.QueryKeys(ctx, alice, keyserver.QueryRequest{DeviceKeys: map[string][]string{alice: nil, bob: nil}})
	if _, ok := signaturesBy(t, resp.DeviceKeys[alice]["D1"], alice)["ed25519:"+cs.selfSigning.PublicBase64()]; !ok {
		t.Error("the device is not shown signed by the self-signing key")
	}
	if _, ok := signaturesBy(t, resp.MasterKeys[alice], alice)["ed25519:D1"]; !ok {
		t.Error("the master key is not shown signed by the device")
	}
	if _, ok := signaturesBy(t, resp.MasterKeys[bob], alice)["ed25519:"+cs.userSigning.PublicBase64()]; !ok {
		t.Error("Alice does not see her signature of Bob's master key")
	}

	// Who Alice has verified is between her and her devices.
	asCarol, _ := h.keys.QueryKeys(ctx, carol, keyserver.QueryRequest{DeviceKeys: map[string][]string{bob: nil}})
	if sigs := signaturesBy(t, asCarol.MasterKeys[bob], alice); len(sigs) != 0 {
		t.Errorf("another user sees Alice's signature of Bob's key: %v", sigs)
	}

	// A signature that does not verify against the stored key is refused,
	// and so is one of a key that does not exist.
	stripped["algorithms"] = []string{"tampered"}
	failures, err = h.keys.UploadSignatures(ctx, alice, map[string]map[string]json.RawMessage{
		alice: {
			"D1":   signed(t, alice, cs.selfSigning, stripped),
			"NOPE": signed(t, alice, cs.selfSigning, stripped),
		},
	})
	if err != nil {
		t.Fatal(err)
	}
	if failures[alice]["D1"].ErrCode != "M_INVALID_SIGNATURE" {
		t.Errorf("a signature over a different object = %+v", failures[alice]["D1"])
	}
	if failures[alice]["NOPE"].ErrCode != "M_NOT_FOUND" {
		t.Errorf("a signature of an unknown device = %+v", failures[alice]["NOPE"])
	}
}

func TestDeletedDevicesLoseTheirKeys(t *testing.T) {
	ctx := t.Context()
	h := newHarness(t, nil)
	_, d1 := device(t, alice, "D1")
	if _, err := h.keys.UploadKeys(ctx, alice, "D1", keyserver.UploadRequest{
		DeviceKeys:  d1,
		OneTimeKeys: map[string]json.RawMessage{"signed_curve25519:AAA": json.RawMessage(`{}`)},
	}); err != nil {
		t.Fatal(err)
	}

	h.keys.DevicesDeleted(ctx, "alice", []string{"D1"})

	resp, _ := h.keys.QueryKeys(ctx, bob, keyserver.QueryRequest{DeviceKeys: map[string][]string{alice: nil}})
	if len(resp.DeviceKeys[alice]) != 0 {
		t.Errorf("keys of a deleted device are still served: %v", resp.DeviceKeys[alice])
	}
	if counts, _ := h.keys.OneTimeKeyCounts(ctx, alice, "D1"); counts["signed_curve25519"] != 0 {
		t.Errorf("one-time keys of a deleted device survived: %v", counts)
	}
	updates := h.outbound.ofType(federation.EDUDeviceListUp)
	var last federation.DeviceListUpdateContent
	_ = json.Unmarshal(updates[len(updates)-1].edu.Content, &last)
	if !last.Deleted || last.DeviceID != "D1" || len(last.PrevID) != 1 {
		t.Errorf("the last device list EDU = %+v, want D1 deleted after its upload", last)
	}
}

func TestRemoteKeyChangesOnlyConcernSharedUsers(t *testing.T) {
	ctx := t.Context()
	h := newHarness(t, nil)

	stranger := federation.DeviceListUpdateContent{UserID: dave, DeviceID: "V1", StreamID: 1}
	if err := h.keys.RemoteDeviceListUpdate(ctx, stranger); err != nil {
		t.Fatal(err)
	}
	if pos, _ := h.store.DeviceListPosition(ctx, dave); pos != 0 {
		t.Error("an update about a user nobody here shares a room with was recorded")
	}
	if _, ok, _ := h.store.RemoteKeys(ctx, dave); ok {
		t.Error("an update about a stranger left something in the cache")
	}

	if err := h.keys.RemoteDeviceListUpdate(ctx, federation.DeviceListUpdateContent{UserID: carol, DeviceID: "C1", StreamID: 1}); err != nil {
		t.Fatal(err)
	}
	if pos, _ := h.store.DeviceListPosition(ctx, carol); pos == 0 {
		t.Error("an update about a user sharing a room was not recorded")
	}
	if !h.notifier.wasWoken(alice) {
		t.Error("the local user sharing a room was not woken")
	}
	if len(h.outbound.sent) != 0 {
		t.Errorf("a remote update was echoed over federation: %+v", h.outbound.sent)
	}
}

func TestKeyBackupVersions(t *testing.T) {
	ctx := t.Context()
	h := newHarness(t, nil)

	v1, err := h.keys.CreateBackup(ctx, alice, "m.megolm_backup.v1.curve25519-aes-sha2", json.RawMessage(`{"public_key":"a"}`))
	if err != nil {
		t.Fatal(err)
	}
	if _, err := h.keys.CreateBackup(ctx, alice, "", json.RawMessage(`{}`)); !errors.Is(err, keyserver.ErrMissingParam) {
		t.Errorf("a backup with no algorithm = %v", err)
	}
	if _, err := h.keys.CreateBackup(ctx, alice, "alg", json.RawMessage(`[1]`)); !errors.Is(err, keyserver.ErrInvalidParam) {
		t.Errorf("auth_data that is not an object = %v", err)
	}

	rooms := map[string]keyserver.RoomKeyBackup{"!r:x": {Sessions: map[string]keyserver.KeyBackupData{
		"s1": {FirstMessageIndex: 1, SessionData: json.RawMessage(`{"ciphertext":"c"}`)},
	}}}
	result, err := h.keys.PutBackupKeys(ctx, alice, v1, rooms)
	if err != nil || result.Count != 1 {
		t.Fatalf("PutBackupKeys = %+v, %v", result, err)
	}

	v2, _ := h.keys.CreateBackup(ctx, alice, "m.megolm_backup.v1.curve25519-aes-sha2", json.RawMessage(`{"public_key":"b"}`))
	var wrong *keyserver.WrongBackupVersionError
	if _, err := h.keys.PutBackupKeys(ctx, alice, v1, rooms); !errors.As(err, &wrong) || wrong.Current != v2 {
		t.Errorf("writing to an old version = %v, want WrongBackupVersionError{%s}", err, v2)
	}
	if _, err := h.keys.PutBackupKeys(ctx, alice, "99", rooms); !errors.Is(err, keyserver.ErrNoSuchBackup) {
		t.Errorf("writing to a version that does not exist = %v", err)
	}

	if err := h.keys.UpdateBackup(ctx, alice, v2, "another.algorithm", "", json.RawMessage(`{}`)); !errors.Is(err, keyserver.ErrInvalidParam) {
		t.Errorf("changing a version's algorithm = %v", err)
	}
	if err := h.keys.UpdateBackup(ctx, alice, v2, "m.megolm_backup.v1.curve25519-aes-sha2", v1, json.RawMessage(`{}`)); !errors.Is(err, keyserver.ErrInvalidParam) {
		t.Errorf("a body version that is not the path's = %v", err)
	}

	old, err := h.keys.BackupKeys(ctx, alice, v1, "", "")
	if err != nil || len(old["!r:x"].Sessions) != 1 {
		t.Errorf("an old version's keys = %v, %v; still readable", old, err)
	}
}