Implement server notices (#2180)

* Add server_notices config

* Disallow rejecting "server notice" invites

* Update config

* Slightly refactor sendEvent and CreateRoom so it can be reused

* Implement unspecced server notices

* Validate the request

* Set the user api when starting

* Rename function/variables

* Update comments

* Update config

* Set the avatar on account creation

* Update test

* Only create the account when starting
Only add routes if sever notices are enabled

* Use reserver username
Check that we actually got roomData

* Add check for admin account
Enable server notices for CI
Return same values as Synapse

* Add custom error for rejecting server notice invite

* Move building an invite to it's own function, for reusability

* Don't create new rooms, use the existing one (follow Synapse behavior)

Co-authored-by: kegsay <kegan@matrix.org>

6 files changed, 61 insertions, 10 deletions

diff --git a/roomserver/api/api.go b/roomserver/api/api.go
index e6d37e8f..bcbf0e4f 100644
--- a/roomserver/api/api.go
+++ b/roomserver/api/api.go
@@ -3,9 +3,11 @@ package api
 import (
 	"context"
 
+	"github.com/matrix-org/gomatrixserverlib"
+
 	asAPI "github.com/matrix-org/dendrite/appservice/api"
 	fsAPI "github.com/matrix-org/dendrite/federationapi/api"
-	"github.com/matrix-org/gomatrixserverlib"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
 )
 
 // RoomserverInputAPI is used to write events to the room server.
@@ -14,6 +16,7 @@ type RoomserverInternalAPI interface {
 	// interdependencies between the roomserver and other input APIs
 	SetFederationAPI(fsAPI fsAPI.FederationInternalAPI, keyRing *gomatrixserverlib.KeyRing)
 	SetAppserviceAPI(asAPI asAPI.AppServiceQueryAPI)
+	SetUserAPI(userAPI userapi.UserInternalAPI)
 
 	InputRoomEvents(
 		ctx context.Context,
diff --git a/roomserver/api/api_trace.go b/roomserver/api/api_trace.go
index 16f52abb..88b37215 100644
--- a/roomserver/api/api_trace.go
+++ b/roomserver/api/api_trace.go
@@ -5,10 +5,12 @@ import (
 	"encoding/json"
 	"fmt"
 
-	asAPI "github.com/matrix-org/dendrite/appservice/api"
-	fsAPI "github.com/matrix-org/dendrite/federationapi/api"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
+
+	asAPI "github.com/matrix-org/dendrite/appservice/api"
+	fsAPI "github.com/matrix-org/dendrite/federationapi/api"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
 )
 
 // RoomserverInternalAPITrace wraps a RoomserverInternalAPI and logs the
@@ -25,6 +27,10 @@ func (t *RoomserverInternalAPITrace) SetAppserviceAPI(asAPI asAPI.AppServiceQuer
 	t.Impl.SetAppserviceAPI(asAPI)
 }
 
+func (t *RoomserverInternalAPITrace) SetUserAPI(userAPI userapi.UserInternalAPI) {
+	t.Impl.SetUserAPI(userAPI)
+}
+
 func (t *RoomserverInternalAPITrace) InputRoomEvents(
 	ctx context.Context,
 	req *InputRoomEventsRequest,
diff --git a/roomserver/api/perform.go b/roomserver/api/perform.go
index 51cbcb1a..d640858a 100644
--- a/roomserver/api/perform.go
+++ b/roomserver/api/perform.go
@@ -95,6 +95,8 @@ type PerformLeaveRequest struct {
 }
 
 type PerformLeaveResponse struct {
+	Code    int         `json:"code,omitempty"`
+	Message interface{} `json:"message,omitempty"`
 }
 
 type PerformInviteRequest struct {
diff --git a/roomserver/internal/api.go b/roomserver/internal/api.go
index e58f11c1..10c8c844 100644
--- a/roomserver/internal/api.go
+++ b/roomserver/internal/api.go
@@ -15,6 +15,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/storage"
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/setup/process"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/nats-io/nats.go"
 	"github.com/sirupsen/logrus"
@@ -159,6 +160,10 @@ func (r *RoomserverInternalAPI) SetFederationAPI(fsAPI fsAPI.FederationInternalA
 	}
 }
 
+func (r *RoomserverInternalAPI) SetUserAPI(userAPI userapi.UserInternalAPI) {
+	r.Leaver.UserAPI = userAPI
+}
+
 func (r *RoomserverInternalAPI) SetAppserviceAPI(asAPI asAPI.AppServiceQueryAPI) {
 	r.asAPI = asAPI
 }
diff --git a/roomserver/internal/perform/perform_leave.go b/roomserver/internal/perform/perform_leave.go
index 12784e5f..49ddd481 100644
--- a/roomserver/internal/perform/perform_leave.go
+++ b/roomserver/internal/perform/perform_leave.go
@@ -16,25 +16,29 @@ package perform
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"strings"
 
+	"github.com/matrix-org/gomatrix"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+	"github.com/sirupsen/logrus"
+
 	fsAPI "github.com/matrix-org/dendrite/federationapi/api"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/internal/helpers"
 	"github.com/matrix-org/dendrite/roomserver/internal/input"
 	"github.com/matrix-org/dendrite/roomserver/storage"
 	"github.com/matrix-org/dendrite/setup/config"
-	"github.com/matrix-org/gomatrixserverlib"
-	"github.com/matrix-org/util"
-	"github.com/sirupsen/logrus"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
 )
 
 type Leaver struct {
-	Cfg   *config.RoomServer
-	DB    storage.Database
-	FSAPI fsAPI.FederationInternalAPI
-
+	Cfg     *config.RoomServer
+	DB      storage.Database
+	FSAPI   fsAPI.FederationInternalAPI
+	UserAPI userapi.UserInternalAPI
 	Inputer *input.Inputer
 }
 
@@ -85,6 +89,31 @@ func (r *Leaver) performLeaveRoomByID(
 		if host != r.Cfg.Matrix.ServerName {
 			return r.performFederatedRejectInvite(ctx, req, res, senderUser, eventID)
 		}
+		// check that this is not a "server notice room"
+		accData := &userapi.QueryAccountDataResponse{}
+		if err := r.UserAPI.QueryAccountData(ctx, &userapi.QueryAccountDataRequest{
+			UserID:   req.UserID,
+			RoomID:   req.RoomID,
+			DataType: "m.tag",
+		}, accData); err != nil {
+			return nil, fmt.Errorf("unable to query account data")
+		}
+
+		if roomData, ok := accData.RoomAccountData[req.RoomID]; ok {
+			tagData, ok := roomData["m.tag"]
+			if ok {
+				tags := gomatrix.TagContent{}
+				if err = json.Unmarshal(tagData, &tags); err != nil {
+					return nil, fmt.Errorf("unable to unmarshal tag content")
+				}
+				if _, ok = tags.Tags["m.server_notice"]; ok {
+					// mimic the returned values from Synapse
+					res.Message = "You cannot reject this invite"
+					res.Code = 403
+					return nil, fmt.Errorf("You cannot reject this invite")
+				}
+			}
+		}
 	}
 
 	// There's no invite pending, so first of all we want to find out
diff --git a/roomserver/inthttp/client.go b/roomserver/inthttp/client.go
index a61404ef..99c59660 100644
--- a/roomserver/inthttp/client.go
+++ b/roomserver/inthttp/client.go
@@ -11,6 +11,8 @@ import (
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/httputil"
 	"github.com/matrix-org/dendrite/roomserver/api"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
+
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/opentracing/opentracing-go"
 )
@@ -90,6 +92,10 @@ func (h *httpRoomserverInternalAPI) SetFederationAPI(fsAPI fsInputAPI.Federation
 func (h *httpRoomserverInternalAPI) SetAppserviceAPI(asAPI asAPI.AppServiceQueryAPI) {
 }
 
+// SetUserAPI no-ops in HTTP client mode as there is no chicken/egg scenario
+func (h *httpRoomserverInternalAPI) SetUserAPI(userAPI userapi.UserInternalAPI) {
+}
+
 // SetRoomAlias implements RoomserverAliasAPI
 func (h *httpRoomserverInternalAPI) SetRoomAlias(
 	ctx context.Context,