Add canonical alias support (#2236)

* Add canonical support

* Add test

* Check that the send event is actually an m.room.canonical_alias
Check that we got an event from the database

* Update to get correct required events

* Add flakey test to blacklist

clientapi/jsonerror/jsonerror.go

@@ -58,6 +58,11 @@ func BadJSON(msg string) *MatrixError {
 	return &MatrixError{"M_BAD_JSON", msg}
 }
 
+// BadAlias is an error when the client supplies a bad alias.
+func BadAlias(msg string) *MatrixError {
+	return &MatrixError{"M_BAD_ALIAS", msg}
+}
+
 // NotJSON is an error when the client supplies something that is not JSON
 // to a JSON endpoint.
 func NotJSON(msg string) *MatrixError {

clientapi/routing/sendevent.go

@@ -16,6 +16,8 @@ package routing
 
 import (
 	"context"
+	"encoding/json"
+	"fmt"
 	"net/http"
 	"sync"
 	"time"
@@ -120,6 +122,40 @@ func SendEvent(
 	}
 	timeToGenerateEvent := time.Since(startedGeneratingEvent)
 
+	// validate that the aliases exists
+	if eventType == gomatrixserverlib.MRoomCanonicalAlias && stateKey != nil && *stateKey == "" {
+		aliasReq := api.AliasEvent{}
+		if err = json.Unmarshal(e.Content(), &aliasReq); err != nil {
+			return util.ErrorResponse(fmt.Errorf("unable to parse alias event: %w", err))
+		}
+		if !aliasReq.Valid() {
+			return util.JSONResponse{
+				Code: http.StatusBadRequest,
+				JSON: jsonerror.InvalidParam("Request contains invalid aliases."),
+			}
+		}
+		aliasRes := &api.GetAliasesForRoomIDResponse{}
+		if err = rsAPI.GetAliasesForRoomID(req.Context(), &api.GetAliasesForRoomIDRequest{RoomID: roomID}, aliasRes); err != nil {
+			return jsonerror.InternalServerError()
+		}
+		var found int
+		requestAliases := append(aliasReq.AltAliases, aliasReq.Alias)
+		for _, alias := range aliasRes.Aliases {
+			for _, altAlias := range requestAliases {
+				if altAlias == alias {
+					found++
+				}
+			}
+		}
+		// check that we found at least the same amount of existing aliases as are in the request
+		if aliasReq.Alias != "" && found < len(requestAliases) {
+			return util.JSONResponse{
+				Code: http.StatusBadRequest,
+				JSON: jsonerror.BadAlias("No matching alias found."),
+			}
+		}
+	}
+
 	var txnAndSessionID *api.TransactionID
 	if txnID != nil {
 		txnAndSessionID = &api.TransactionID{

roomserver/api/alias.go

@@ -14,6 +14,8 @@
 
 package api
 
+import "regexp"
+
 // SetRoomAliasRequest is a request to SetRoomAlias
 type SetRoomAliasRequest struct {
 	// ID of the user setting the alias
@@ -84,3 +86,20 @@ type RemoveRoomAliasResponse struct {
 	// Did we remove it?
 	Removed bool `json:"removed"`
 }
+
+type AliasEvent struct {
+	Alias      string   `json:"alias"`
+	AltAliases []string `json:"alt_aliases"`
+}
+
+var validateAliasRegex = regexp.MustCompile("^#.*:.+$")
+
+func (a AliasEvent) Valid() bool {
+	for _, alias := range a.AltAliases {
+		if !validateAliasRegex.MatchString(alias) {
+			return false
+		}
+	}
+	return a.Alias == "" || validateAliasRegex.MatchString(a.Alias)
+}
+

roomserver/api/alias_test.go

@@ -0,0 +1,62 @@
+package api
+
+import "testing"
+
+func TestAliasEvent_Valid(t *testing.T) {
+	type fields struct {
+		Alias      string
+		AltAliases []string
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		want   bool
+	}{
+		{
+			name: "empty alias",
+			fields: fields{
+				Alias: "",
+			},
+			want: true,
+		},
+		{
+			name: "empty alias, invalid alt aliases",
+			fields: fields{
+				Alias: "",
+				AltAliases: []string{ "%not:valid.local"},
+			},
+		},
+		{
+			name: "valid alias, invalid alt aliases",
+			fields: fields{
+				Alias: "#valid:test.local",
+				AltAliases: []string{ "%not:valid.local"},
+			},
+		},
+		{
+			name: "empty alias, invalid alt aliases",
+			fields: fields{
+				Alias: "",
+				AltAliases: []string{ "%not:valid.local"},
+			},
+		},
+		{
+			name: "invalid alias",
+			fields: fields{
+				Alias: "%not:valid.local",
+				AltAliases: []string{ },
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			a := AliasEvent{
+				Alias:      tt.fields.Alias,
+				AltAliases: tt.fields.AltAliases,
+			}
+			if got := a.Valid(); got != tt.want {
+				t.Errorf("Valid() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

roomserver/internal/alias.go

@@ -16,12 +16,18 @@ package internal
 
 import (
 	"context"
+	"database/sql"
+	"errors"
 	"fmt"
-
-	"github.com/matrix-org/dendrite/roomserver/api"
-	"github.com/matrix-org/gomatrixserverlib"
+	"time"
 
 	asAPI "github.com/matrix-org/dendrite/appservice/api"
+	"github.com/matrix-org/dendrite/internal/eventutil"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/dendrite/roomserver/internal/helpers"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
 )
 
 // RoomserverInternalAPIDatabase has the storage APIs needed to implement the alias API.
@@ -183,6 +189,57 @@ func (r *RoomserverInternalAPI) RemoveRoomAlias(
 		}
 	}
 
+	ev, err := r.DB.GetStateEvent(ctx, roomID, gomatrixserverlib.MRoomCanonicalAlias, "")
+	if err != nil && err != sql.ErrNoRows {
+		return err
+	} else if ev != nil {
+		stateAlias := gjson.GetBytes(ev.Content(), "alias").Str
+		// the alias to remove is currently set as the canonical alias, remove it
+		if stateAlias == request.Alias {
+			res, err := sjson.DeleteBytes(ev.Content(), "alias")
+			if err != nil {
+				return err
+			}
+
+			sender := request.UserID
+			if request.UserID != ev.Sender() {
+				sender = ev.Sender()
+			}
+
+			builder := &gomatrixserverlib.EventBuilder{
+				Sender:   sender,
+				RoomID:   ev.RoomID(),
+				Type:     ev.Type(),
+				StateKey: ev.StateKey(),
+				Content:  res,
+			}
+
+			eventsNeeded, err := gomatrixserverlib.StateNeededForEventBuilder(builder)
+			if err != nil {
+				return fmt.Errorf("gomatrixserverlib.StateNeededForEventBuilder: %w", err)
+			}
+			if len(eventsNeeded.Tuples()) == 0 {
+				return errors.New("expecting state tuples for event builder, got none")
+			}
+
+			stateRes := &api.QueryLatestEventsAndStateResponse{}
+			if err := helpers.QueryLatestEventsAndState(ctx, r.DB, &api.QueryLatestEventsAndStateRequest{RoomID: roomID, StateToFetch: eventsNeeded.Tuples()}, stateRes); err != nil {
+				return err
+			}
+
+			newEvent, err := eventutil.BuildEvent(ctx, builder, r.Cfg.Matrix, time.Now(), &eventsNeeded, stateRes)
+			if err != nil {
+				return err
+			}
+
+			err = api.SendEvents(ctx, r.RSAPI, api.KindNew, []*gomatrixserverlib.HeaderedEvent{newEvent}, r.ServerName, r.ServerName, nil, false)
+			if err != nil {
+				return err
+			}
+
+		}
+	}
+
 	// Remove the alias from the database
 	if err := r.DB.RemoveRoomAlias(ctx, request.Alias); err != nil {
 		return err

sytest-blacklist

@@ -31,6 +31,7 @@ Remove group role
 
 # Flakey
 AS-ghosted users can use rooms themselves
+/context/ with lazy_load_members filter works
 
 # Flakey, need additional investigation
 Messages that notify from another user increment notification_count

sytest-whitelist

@@ -648,7 +648,7 @@ Device list doesn't change if remote server is down
 /context/ on joined room works
 /context/ on non world readable room does not work
 /context/ returns correct number of events
-/context/ with lazy_load_members filter works
+
 GET /rooms/:room_id/messages lazy loads members correctly
 Can query remote device keys using POST after notification
 Device deletion propagates over federation
@@ -659,4 +659,8 @@ registration accepts non-ascii passwords
 registration with inhibit_login inhibits login
 The operation must be consistent through an interactive authentication session
 Multiple calls to /sync should not cause 500 errors
-/context/ with lazy_load_members filter works
+
+Canonical alias can be set
+Canonical alias can include alt_aliases
+Can delete canonical alias
+Multiple calls to /sync should not cause 500 errors