Peeking via MSC2753

README.md

@@ -81,6 +81,18 @@ matrixdotorg/sytest-dendrite:latest tests/50federation/40devicelists.pl
 ```
 See [sytest.md](docs/sytest.md) for the full description of these flags.
 
+You can try running sytest outside of docker for faster runs, but the dependencies can be temperamental
+and we recommend using docker where possible.
+```
+cd sytest
+export PERL5LIB=$HOME/lib/perl5
+export PERL_MB_OPT=--install_base=$HOME
+export PERL_MM_OPT=INSTALL_BASE=$HOME
+./install-deps.pl
+
+./run-tests.pl -I Dendrite::Monolith -d $PATH_TO_DENDRITE_BINARIES
+```
+
 Sometimes Sytest is testing the wrong thing or is flakey, so it will need to be patched.
 Ask on `#dendrite-dev:matrix.org` if you think this is the case for you and we'll be happy to help.
 

clientapi/routing/joinroom.go

@@ -52,7 +52,7 @@ func JoinRoomByIDOrAlias(
 		}
 	}
 
-	// If content was provided in the request then incude that
+	// If content was provided in the request then include that
 	// in the request. It'll get used as a part of the membership
 	// event content.
 	_ = httputil.UnmarshalJSONRequest(req, &joinReq.Content)

clientapi/routing/peekroom.go

@@ -0,0 +1,80 @@
+// Copyright 2020 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package routing
+
+import (
+	"net/http"
+
+	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/dendrite/userapi/storage/accounts"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+func PeekRoomByIDOrAlias(
+	req *http.Request,
+	device *api.Device,
+	rsAPI roomserverAPI.RoomserverInternalAPI,
+	accountDB accounts.Database,
+	roomIDOrAlias string,
+) util.JSONResponse {
+	// if this is a remote roomIDOrAlias, we have to ask the roomserver (or federation sender?) to
+	// to call /peek and /state on the remote server.
+	// TODO: in future we could skip this if we know we're already participating in the room,
+	// but this is fiddly in case we stop participating in the room.
+
+	// then we create a local peek.
+	peekReq := roomserverAPI.PerformPeekRequest{
+		RoomIDOrAlias: roomIDOrAlias,
+		UserID:        device.UserID,
+		DeviceID:	   device.ID,
+	}
+	peekRes := roomserverAPI.PerformPeekResponse{}
+
+	// Check to see if any ?server_name= query parameters were
+	// given in the request.
+	if serverNames, ok := req.URL.Query()["server_name"]; ok {
+		for _, serverName := range serverNames {
+			peekReq.ServerNames = append(
+				peekReq.ServerNames,
+				gomatrixserverlib.ServerName(serverName),
+			)
+		}
+	}
+
+	// Ask the roomserver to perform the peek.
+	rsAPI.PerformPeek(req.Context(), &peekReq, &peekRes)
+	if peekRes.Error != nil {
+		return peekRes.Error.JSONResponse()
+	}
+
+	// if this user is already joined to the room, we let them peek anyway
+	// (given they might be about to part the room, and it makes things less fiddly)
+
+
+	// Peeking stops if none of the devices who started peeking have been
+	// /syncing for a while, or if everyone who was peeking calls /leave
+	// (or /unpeek with a server_name param? or DELETE /peek?)
+	// on the peeked room.
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		// TODO: Put the response struct somewhere internal.
+		JSON: struct {
+			RoomID string `json:"room_id"`
+		}{peekRes.RoomID},
+	}
+}

clientapi/routing/routing.go

@@ -101,6 +101,17 @@ func Setup(
 			)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
+	r0mux.Handle("/peek/{roomIDOrAlias}",
+		httputil.MakeAuthAPI(gomatrixserverlib.Join, userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
+			return PeekRoomByIDOrAlias(
+				req, device, rsAPI, accountDB, vars["roomIDOrAlias"],
+			)
+		}),
+	).Methods(http.MethodPost, http.MethodOptions)
 	r0mux.Handle("/joined_rooms",
 		httputil.MakeAuthAPI("joined_rooms", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return GetJoinedRooms(req, device, stateAPI)

docs/peeking.md

@@ -0,0 +1,19 @@
+## Peeking
+
+Peeking is implemented as per [MSC2753](https://github.com/matrix-org/matrix-doc/pull/2753).
+
+Implementationwise, this means:
+ * Users call `/peek` and `/unpeek` on the clientapi from a given device.
+ * The clientapi delegates these via HTTP to the roomserver, which coordinates peeking in general for a given room
+ * The roomserver writes an NewPeek event into the kafka log headed to the syncserver
+ * The syncserver tracks the existence of the local peek in its DB, and then starts waking up the peeking devices for the room in question, putting it in the `peek` section of the /sync response.
+
+Questions (given this is [my](https://github.com/ara4n) first time hacking on Dendrite):
+ * The whole clientapi -> roomserver -> syncapi flow to initiate a peek seems very indirect.  Is there a reason not to just let syncapi itself host the implementation of `/peek`?
+
+In future, peeking over federation will be added as per [MSC2444](https://github.com/matrix-org/matrix-doc/pull/2444).
+ * The `roomserver` will kick the `federationsender` much as it does for a federated `/join` in order to trigger a federated `/peek`
+ * The `federationsender` tracks the existence of the remote peek in question
+ * The `federationsender` regularly renews the remote peek as long as there are still peeking devices syncing for it.
+  * TBD: how do we tell if there are no devices currently syncing for a given peeked room?  The syncserver needs to tell the roomserver
+    somehow who then needs to warn the federationsender.

roomserver/api/api.go

@@ -36,6 +36,12 @@ type RoomserverInternalAPI interface {
 		res *PerformLeaveResponse,
 	) error
 
+	PerformPeek(
+		ctx context.Context,
+		req *PerformPeekRequest,
+		res *PerformPeekResponse,
+	)
+
 	PerformPublish(
 		ctx context.Context,
 		req *PerformPublishRequest,

roomserver/api/api_trace.go

@@ -38,6 +38,15 @@ func (t *RoomserverInternalAPITrace) PerformInvite(
 	return t.Impl.PerformInvite(ctx, req, res)
 }
 
+func (t *RoomserverInternalAPITrace) PerformPeek(
+	ctx context.Context,
+	req *PerformPeekRequest,
+	res *PerformPeekResponse,
+) {
+	t.Impl.PerformPeek(ctx, req, res)
+	util.GetLogger(ctx).Infof("PerformPeek req=%+v res=%+v", js(req), js(res))
+}
+
 func (t *RoomserverInternalAPITrace) PerformJoin(
 	ctx context.Context,
 	req *PerformJoinRequest,

roomserver/api/output.go

@@ -46,6 +46,9 @@ const (
 	// - Redact the event and set the corresponding `unsigned` fields to indicate it as redacted.
 	// - Replace the event in the database.
 	OutputTypeRedactedEvent OutputType = "redacted_event"
+
+	// OutputTypeNewPeek indicates that the kafka event is an OutputNewPeek
+	OutputTypeNewPeek OutputType = "new_peek"
 )
 
 // An OutputEvent is an entry in the roomserver output kafka log.
@@ -59,8 +62,10 @@ type OutputEvent struct {
 	NewInviteEvent *OutputNewInviteEvent `json:"new_invite_event,omitempty"`
 	// The content of event with type OutputTypeRetireInviteEvent
 	RetireInviteEvent *OutputRetireInviteEvent `json:"retire_invite_event,omitempty"`
-	// The content of event with type  OutputTypeRedactedEvent
+	// The content of event with type OutputTypeRedactedEvent
 	RedactedEvent *OutputRedactedEvent `json:"redacted_event,omitempty"`
+	// The content of event with type OutputTypeNewPeek
+	NewPeek *OutputNewPeek `json:"new_peek,omitempty"`
 }
 
 // An OutputNewRoomEvent is written when the roomserver receives a new event.
@@ -195,3 +200,11 @@ type OutputRedactedEvent struct {
 	// The value of `unsigned.redacted_because` - the redaction event itself
 	RedactedBecause gomatrixserverlib.HeaderedEvent
 }
+
+// An OutputNewPeek is written whenever a user starts peeking into a room
+// using a given device.
+type OutputNewPeek struct {
+	RoomID string
+	UserID string
+	DeviceID string
+}

roomserver/api/perform.go

@@ -108,6 +108,20 @@ type PerformInviteResponse struct {
 	Error *PerformError
 }
 
+type PerformPeekRequest struct {
+	RoomIDOrAlias string                         `json:"room_id_or_alias"`
+	UserID        string                         `json:"user_id"`
+	DeviceID      string                         `json:"device_id"`
+	ServerNames   []gomatrixserverlib.ServerName `json:"server_names"`
+}
+
+type PerformPeekResponse struct {
+	// The room ID, populated on success.
+	RoomID string `json:"room_id"`
+	// If non-nil, the join request failed. Contains more information why it failed.
+	Error *PerformError
+}
+
 // PerformBackfillRequest is a request to PerformBackfill.
 type PerformBackfillRequest struct {
 	// The room to backfill