MSC2444 /peek support in the federation client

federationclient.go

@@ -109,7 +109,7 @@ func (ac *FederationClient) MakeJoin(
 	if len(roomVersions) > 0 {
 		var vqs []string
 		for _, v := range roomVersions {
-			vqs = append(vqs, fmt.Sprintf("ver=%s", v))
+			vqs = append(vqs, fmt.Sprintf("ver=%s", url.QueryEscape(string(v))))
 		}
 		versionQueryString = "?" + strings.Join(vqs, "&")
 	}
@@ -323,6 +323,31 @@ func (ac *FederationClient) LookupMissingEvents(
 	return
 }
 
+// Peek starts a peek on a remote server
+func (ac *FederationClient) Peek(
+	ctx context.Context, s ServerName, roomID, peekID string,
+	roomVersions []RoomVersion,
+) (res RespPeek, err error) {
+	versionQueryString := ""
+	if len(roomVersions) > 0 {
+		var vqs []string
+		for _, v := range roomVersions {
+			vqs = append(vqs, fmt.Sprintf("ver=%s", url.QueryEscape(string(v))))
+		}
+		versionQueryString = "?" + strings.Join(vqs, "&")
+	}
+	path := federationPathPrefixV1 + "/peek/" +
+		url.PathEscape(roomID) + "/" +
+		url.PathEscape(peekID) + versionQueryString
+	req := NewFederationRequest("PUT", s, path)
+	var empty struct{}
+	if err = req.SetContent(empty); err != nil {
+		return
+	}
+	err = ac.doRequest(ctx, req, &res)
+	return
+}
+
 // LookupRoomAlias looks up a room alias hosted on the remote server.
 // The domain part of the roomAlias must match the name of the server it is
 // being looked up on.

federationtypes.go

@@ -137,6 +137,21 @@ type RespState struct {
 	AuthEvents []Event `json:"auth_chain"`
 }
 
+// A RespPeek is the content of a response to GET /_matrix/federation/v1/peek/{roomID}/{peekID}
+type RespPeek struct {
+	// How often should we renew the peek?
+	RenewalInterval int64 `json:"renewal_interval"`
+	// A list of events giving the state of the room at the point of the request
+	StateEvents []Event `json:"state"`
+	// A list of events needed to authenticate the state events.
+	AuthEvents []Event `json:"auth_chain"`
+	// The room version that we're trying to peek.
+	RoomVersion RoomVersion `json:"room_version"`
+	// The ID of the event whose state snapshot this is - i.e. the
+	// most recent forward extremity in the room.
+	LatestEvent Event `json:"latest_event"`
+}
+
 // MissingEvents represents a request for missing events.
 // https://matrix.org/docs/spec/server_server/r0.1.3#post-matrix-federation-v1-get-missing-events-roomid
 type MissingEvents struct {
@@ -256,6 +271,58 @@ func (r *RespMissingEvents) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// MarshalJSON implements json.Marshaller
+func (r RespPeek) MarshalJSON() ([]byte, error) {
+	if len(r.StateEvents) == 0 {
+		r.StateEvents = []Event{}
+	}
+	if len(r.AuthEvents) == 0 {
+		r.AuthEvents = []Event{}
+	}
+	return json.Marshal(r)
+}
+
+// UnmarshalJSON implements json.Unmarshaller
+func (r *RespPeek) UnmarshalJSON(data []byte) error {
+	r.AuthEvents = []Event{}
+	r.StateEvents = []Event{}
+	var intermediate struct {
+		RoomVersion     RoomVersion       `json:"room_version"`
+		StateEvents     []json.RawMessage `json:"state"`
+		AuthEvents      []json.RawMessage `json:"auth_chain"`
+		RenewalInterval int64             `json:"renewal_interval"`
+		LatestEvent     json.RawMessage   `json:"latest_event"`
+	}
+	if err := json.Unmarshal(data, &intermediate); err != nil {
+		return fmt.Errorf("RespPeek UnmarshalJSON(intermediate): %w", err)
+	}
+	r.RoomVersion = intermediate.RoomVersion
+	r.RenewalInterval = intermediate.RenewalInterval
+	if _, err := r.RoomVersion.EventFormat(); err != nil {
+		return fmt.Errorf("RespPeek UnmarshalJSON(roomversion): %w", err)
+	}
+	for _, raw := range intermediate.AuthEvents {
+		event, err := NewEventFromUntrustedJSON([]byte(raw), r.RoomVersion)
+		if err != nil {
+			return fmt.Errorf("RespPeek UnmarshalJSON(AuthEvent): %w", err)
+		}
+		r.AuthEvents = append(r.AuthEvents, event)
+	}
+	for _, raw := range intermediate.StateEvents {
+		event, err := NewEventFromUntrustedJSON([]byte(raw), r.RoomVersion)
+		if err != nil {
+			return fmt.Errorf("RespPeek UnmarshalJSON(StateEvent): %w", err)
+		}
+		r.StateEvents = append(r.StateEvents, event)
+	}
+	latestEvent, err := NewEventFromUntrustedJSON([]byte(intermediate.LatestEvent), r.RoomVersion)
+	if err != nil {
+		return fmt.Errorf("RespPeek UnmarshalJSON(StateEvent): %w", err)
+	}
+	r.LatestEvent = latestEvent
+	return nil
+}
+
 // MarshalJSON implements json.Marshaller
 func (r RespState) MarshalJSON() ([]byte, error) {
 	if len(r.StateEvents) == 0 {
@@ -533,6 +600,21 @@ func (r *RespSendJoin) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// ToRespState returns a new RespState with the same data from the given RespPeek
+func (r RespPeek) ToRespState() RespState {
+	if len(r.StateEvents) == 0 {
+		r.StateEvents = []Event{}
+	}
+	if len(r.AuthEvents) == 0 {
+		r.AuthEvents = []Event{}
+	}
+	return RespState{
+		roomVersion: r.RoomVersion,
+		StateEvents: r.StateEvents,
+		AuthEvents:  r.AuthEvents,
+	}
+}
+
 type respSendJoinFields struct {
 	StateEvents []Event    `json:"state"`
 	AuthEvents  []Event    `json:"auth_chain"`