Peeking over federation via MSC2444 (#1391)

* a very very WIP first cut of peeking via MSC2753.

doesn't yet compile or work.
needs to actually add the peeking block into the sync response.
checking in now before it gets any bigger, and to gather any initial feedback on the vague shape of it.

* make PeekingDeviceSet private

* add server_name param

* blind stab at adding a `peek` section to /sync

* make it build

* make it launch

* add peeking to getResponseWithPDUsForCompleteSync

* cancel any peeks when we join a room

* spell out how to runoutside of docker if you want speed

* fix SQL

* remove unnecessary txn for SelectPeeks

* fix s/join/peek/ cargocult fail

* HACK: Track goroutine IDs to determine when we write by the wrong thread

To use: set `DENDRITE_TRACE_SQL=1` then grep for `unsafe`

* Track partition offsets and only log unsafe for non-selects

* Put redactions in the writer goroutine

* Update filters on writer goroutine

* wrap peek storage in goid hack

* use exclusive writer, and MarkPeeksAsOld more efficiently

* don't log ascii in binary at sql trace...

* strip out empty roomd deltas

* re-add txn to SelectPeeks

* re-add accidentally deleted field

* reject peeks for non-worldreadable rooms

* move perform_peek

* fix package

* correctly refactor perform_peek

* WIP of implementing MSC2444

* typo

* Revert "Merge branch 'kegan/HACK-goid-sqlite-db-is-locked' into matthew/peeking"

This reverts commit 3cebd8dbfbccdf82b7930b7b6eda92095ca6ef41, reversing
changes made to ed4b3a58a7855acc43530693cc855b439edf9c7c.

* (almost) make it build

* clean up bad merge

* support SendEventWithState with optional event

* fix build & lint

* fix build & lint

* reinstate federated peeks in the roomserver (doh)

* fix sql thinko

* todo for authenticating state returned by /peek

* support returning current state from QueryStateAndAuthChain

* handle SS /peek

* reimplement SS /peek to prod the RS to tell the FS about the peek

* rename RemotePeeks as OutboundPeeks

* rename remote_peeks_table as outbound_peeks_table

* add perform_handle_remote_peek.go

* flesh out federation doc

* add inbound peeks table and hook it up

* rename ambiguous RemotePeek as InboundPeek

* rename FSAPI's PerformPeek as PerformOutboundPeek

* setup inbound peeks db correctly

* fix api.SendEventWithState with no event

* track latestevent on /peek

* go fmt

* document the peek send stream race better

* fix SendEventWithRewrite not to bail if handed a non-state event

* add fixme

* switch SS /peek to use SendEventWithRewrite

* fix comment

* use reverse topo ordering to find latest extrem

* support postgres for federated peeking

* go fmt

* back out bogus go.mod change

* Fix performOutboundPeekUsingServer

* Fix getAuthChain -> GetAuthChain

* Fix build issues

* Fix build again

* Fix getAuthChain -> GetAuthChain

* Don't repeat outbound peeks for the same room ID to the same servers

* Fix lint

* Don't omitempty to appease sytest

Co-authored-by: Kegan Dougal <kegan@matrix.org>
Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

2 files changed, 136 insertions, 4 deletions

diff --git a/federationapi/routing/peek.go b/federationapi/routing/peek.go
new file mode 100644
index 00000000..8f83cb15
--- /dev/null
+++ b/federationapi/routing/peek.go
@@ -0,0 +1,102 @@
+// 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"
+
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// Peek implements the SS /peek API, handling inbound peeks
+func Peek(
+	httpReq *http.Request,
+	request *gomatrixserverlib.FederationRequest,
+	cfg *config.FederationAPI,
+	rsAPI api.RoomserverInternalAPI,
+	roomID, peekID string,
+	remoteVersions []gomatrixserverlib.RoomVersion,
+) util.JSONResponse {
+	// TODO: check if we're just refreshing an existing peek by querying the federationsender
+
+	verReq := api.QueryRoomVersionForRoomRequest{RoomID: roomID}
+	verRes := api.QueryRoomVersionForRoomResponse{}
+	if err := rsAPI.QueryRoomVersionForRoom(httpReq.Context(), &verReq, &verRes); err != nil {
+		return util.JSONResponse{
+			Code: http.StatusInternalServerError,
+			JSON: jsonerror.InternalServerError(),
+		}
+	}
+
+	// Check that the room that the peeking server is trying to peek is actually
+	// one of the room versions that they listed in their supported ?ver= in
+	// the peek URL.
+	remoteSupportsVersion := false
+	for _, v := range remoteVersions {
+		if v == verRes.RoomVersion {
+			remoteSupportsVersion = true
+			break
+		}
+	}
+	// If it isn't, stop trying to peek the room.
+	if !remoteSupportsVersion {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.IncompatibleRoomVersion(verRes.RoomVersion),
+		}
+	}
+
+	// TODO: Check history visibility
+
+	// tell the peeking server to renew every hour
+	renewalInterval := int64(60 * 60 * 1000 * 1000)
+
+	var response api.PerformInboundPeekResponse
+	err := rsAPI.PerformInboundPeek(
+		httpReq.Context(),
+		&api.PerformInboundPeekRequest{
+			RoomID:          roomID,
+			PeekID:          peekID,
+			ServerName:      request.Origin(),
+			RenewalInterval: renewalInterval,
+		},
+		&response,
+	)
+	if err != nil {
+		resErr := util.ErrorResponse(err)
+		return resErr
+	}
+
+	if !response.RoomExists {
+		return util.JSONResponse{Code: http.StatusNotFound, JSON: nil}
+	}
+
+	respPeek := gomatrixserverlib.RespPeek{
+		StateEvents:     gomatrixserverlib.UnwrapEventHeaders(response.StateEvents),
+		AuthEvents:      gomatrixserverlib.UnwrapEventHeaders(response.AuthChainEvents),
+		RoomVersion:     response.RoomVersion,
+		LatestEvent:     response.LatestEvent.Unwrap(),
+		RenewalInterval: renewalInterval,
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: respPeek,
+	}
+}
diff --git a/federationapi/routing/routing.go b/federationapi/routing/routing.go
index c957e26d..7e76a143 100644
--- a/federationapi/routing/routing.go
+++ b/federationapi/routing/routing.go
@@ -229,7 +229,37 @@ func Setup(
 		},
 	)).Methods(http.MethodGet)
 
-	v1fedmux.Handle("/make_join/{roomID}/{eventID}", httputil.MakeFedAPI(
+	v1fedmux.Handle("/peek/{roomID}/{peekID}", httputil.MakeFedAPI(
+		"federation_peek", cfg.Matrix.ServerName, keys, wakeup,
+		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest, vars map[string]string) util.JSONResponse {
+			if roomserverAPI.IsServerBannedFromRoom(httpReq.Context(), rsAPI, vars["roomID"], request.Origin()) {
+				return util.JSONResponse{
+					Code: http.StatusForbidden,
+					JSON: jsonerror.Forbidden("Forbidden by server ACLs"),
+				}
+			}
+			roomID := vars["roomID"]
+			peekID := vars["peekID"]
+			queryVars := httpReq.URL.Query()
+			remoteVersions := []gomatrixserverlib.RoomVersion{}
+			if vers, ok := queryVars["ver"]; ok {
+				// The remote side supplied a ?ver= so use that to build up the list
+				// of supported room versions
+				for _, v := range vers {
+					remoteVersions = append(remoteVersions, gomatrixserverlib.RoomVersion(v))
+				}
+			} else {
+				// The remote side didn't supply a ?ver= so just assume that they only
+				// support room version 1
+				remoteVersions = append(remoteVersions, gomatrixserverlib.RoomVersionV1)
+			}
+			return Peek(
+				httpReq, request, cfg, rsAPI, roomID, peekID, remoteVersions,
+			)
+		},
+	)).Methods(http.MethodPut, http.MethodDelete)
+
+	v1fedmux.Handle("/make_join/{roomID}/{userID}", httputil.MakeFedAPI(
 		"federation_make_join", cfg.Matrix.ServerName, keys, wakeup,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest, vars map[string]string) util.JSONResponse {
 			if roomserverAPI.IsServerBannedFromRoom(httpReq.Context(), rsAPI, vars["roomID"], request.Origin()) {
@@ -239,11 +269,11 @@ func Setup(
 				}
 			}
 			roomID := vars["roomID"]
-			eventID := vars["eventID"]
+			userID := vars["userID"]
 			queryVars := httpReq.URL.Query()
 			remoteVersions := []gomatrixserverlib.RoomVersion{}
 			if vers, ok := queryVars["ver"]; ok {
-				// The remote side supplied a ?=ver so use that to build up the list
+				// The remote side supplied a ?ver= so use that to build up the list
 				// of supported room versions
 				for _, v := range vers {
 					remoteVersions = append(remoteVersions, gomatrixserverlib.RoomVersion(v))
@@ -255,7 +285,7 @@ func Setup(
 				remoteVersions = append(remoteVersions, gomatrixserverlib.RoomVersionV1)
 			}
 			return MakeJoin(
-				httpReq, request, cfg, rsAPI, roomID, eventID, remoteVersions,
+				httpReq, request, cfg, rsAPI, roomID, userID, remoteVersions,
 			)
 		},
 	)).Methods(http.MethodGet)