mirror of
https://github.com/matrix-org/dendrite.git
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376 lines
12 KiB
Go
376 lines
12 KiB
Go
// Copyright 2020 The Matrix.org Foundation C.I.C.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package msc2836 'Threading' implements https://github.com/matrix-org/matrix-doc/pull/2836
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package msc2836
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import (
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"github.com/matrix-org/dendrite/clientapi/jsonerror"
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"github.com/matrix-org/dendrite/internal/hooks"
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"github.com/matrix-org/dendrite/internal/httputil"
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"github.com/matrix-org/dendrite/internal/setup"
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roomserver "github.com/matrix-org/dendrite/roomserver/api"
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userapi "github.com/matrix-org/dendrite/userapi/api"
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"github.com/matrix-org/gomatrixserverlib"
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"github.com/matrix-org/util"
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)
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const constRelType = "m.reference"
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type EventRelationshipRequest struct {
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EventID string `json:"event_id"`
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MaxDepth int `json:"max_depth"`
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MaxBreadth int `json:"max_breadth"`
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Limit int `json:"limit"`
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DepthFirst *bool `json:"depth_first"`
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RecentFirst *bool `json:"recent_first"`
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IncludeParent *bool `json:"include_parent"`
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IncludeChildren *bool `json:"include_children"`
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Direction string `json:"direction"`
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Batch string `json:"batch"`
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}
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func (r *EventRelationshipRequest) applyDefaults() {
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if r.Limit > 100 || r.Limit < 1 {
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r.Limit = 100
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}
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if r.MaxBreadth == 0 {
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r.MaxBreadth = 10
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}
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if r.MaxDepth == 0 {
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r.MaxDepth = 3
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}
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t := true
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f := false
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if r.DepthFirst == nil {
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r.DepthFirst = &f
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}
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if r.RecentFirst == nil {
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r.RecentFirst = &t
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}
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if r.IncludeParent == nil {
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r.IncludeParent = &f
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}
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if r.IncludeChildren == nil {
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r.IncludeChildren = &f
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}
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if r.Direction != "up" {
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r.Direction = "down"
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}
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}
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type EventRelationshipResponse struct {
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Events []gomatrixserverlib.ClientEvent `json:"events"`
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NextBatch string `json:"next_batch"`
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Limited bool `json:"limited"`
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}
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// Enable this MSC
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func Enable(base *setup.BaseDendrite, rsAPI roomserver.RoomserverInternalAPI, userAPI userapi.UserInternalAPI) error {
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db, err := NewDatabase(&base.Cfg.MSCs.Database)
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if err != nil {
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return fmt.Errorf("Cannot enable MSC2836: %w", err)
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}
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hooks.Enable()
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hooks.Attach(hooks.KindNewEvent, func(headeredEvent interface{}) {
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he := headeredEvent.(*gomatrixserverlib.HeaderedEvent)
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hookErr := db.StoreRelation(context.Background(), he)
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if hookErr != nil {
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util.GetLogger(context.Background()).WithError(hookErr).Error(
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"failed to StoreRelation",
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)
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}
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})
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base.PublicClientAPIMux.Handle("/unstable/event_relationships",
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httputil.MakeAuthAPI("eventRelationships", userAPI, eventRelationshipHandler(db, rsAPI)),
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).Methods(http.MethodPost, http.MethodOptions)
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return nil
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}
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func eventRelationshipHandler(db Database, rsAPI roomserver.RoomserverInternalAPI) func(*http.Request, *userapi.Device) util.JSONResponse {
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return func(req *http.Request, device *userapi.Device) util.JSONResponse {
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var relation EventRelationshipRequest
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if err := json.NewDecoder(req.Body).Decode(&relation); err != nil {
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util.GetLogger(req.Context()).WithError(err).Error("failed to decode HTTP request as JSON")
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return util.JSONResponse{
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Code: 400,
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JSON: jsonerror.BadJSON(fmt.Sprintf("invalid json: %s", err)),
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}
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}
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// Sanity check request and set defaults.
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relation.applyDefaults()
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var res EventRelationshipResponse
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var returnEvents []*gomatrixserverlib.HeaderedEvent
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// Can the user see (according to history visibility) event_id? If no, reject the request, else continue.
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event := getEventIfVisible(req.Context(), rsAPI, relation.EventID, device.UserID)
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if event == nil {
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return util.JSONResponse{
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Code: 403,
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JSON: jsonerror.Forbidden("Event does not exist or you are not authorised to see it"),
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}
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}
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// Retrieve the event. Add it to response array.
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returnEvents = append(returnEvents, event)
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if *relation.IncludeParent {
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if parentEvent := includeParent(req.Context(), rsAPI, event, device.UserID); parentEvent != nil {
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returnEvents = append(returnEvents, parentEvent)
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}
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}
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if *relation.IncludeChildren {
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remaining := relation.Limit - len(returnEvents)
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if remaining > 0 {
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children, resErr := includeChildren(req.Context(), rsAPI, db, event.EventID(), remaining, *relation.RecentFirst, device.UserID)
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if resErr != nil {
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return *resErr
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}
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returnEvents = append(returnEvents, children...)
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}
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}
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remaining := relation.Limit - len(returnEvents)
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var walkLimited bool
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if remaining > 0 {
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included := make(map[string]bool, len(returnEvents))
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for _, ev := range returnEvents {
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included[ev.EventID()] = true
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}
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var events []*gomatrixserverlib.HeaderedEvent
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events, walkLimited = walkThread(
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req.Context(), db, rsAPI, device.UserID, &relation, included, remaining,
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)
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returnEvents = append(returnEvents, events...)
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}
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res.Events = make([]gomatrixserverlib.ClientEvent, len(returnEvents))
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for i, ev := range returnEvents {
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res.Events[i] = gomatrixserverlib.HeaderedToClientEvent(*ev, gomatrixserverlib.FormatAll)
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}
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res.Limited = remaining == 0 || walkLimited
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return util.JSONResponse{
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Code: 200,
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JSON: res,
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}
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}
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}
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// If include_parent: true and there is a valid m.relationship field in the event,
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// retrieve the referenced event. Apply history visibility check to that event and if it passes, add it to the response array.
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func includeParent(ctx context.Context, rsAPI roomserver.RoomserverInternalAPI, event *gomatrixserverlib.HeaderedEvent, userID string) (parent *gomatrixserverlib.HeaderedEvent) {
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parentID, _, _ := parentChildEventIDs(event)
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if parentID == "" {
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return nil
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}
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return getEventIfVisible(ctx, rsAPI, parentID, userID)
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}
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// If include_children: true, lookup all events which have event_id as an m.relationship
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// Apply history visibility checks to all these events and add the ones which pass into the response array,
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// honouring the recent_first flag and the limit.
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func includeChildren(ctx context.Context, rsAPI roomserver.RoomserverInternalAPI, db Database, parentID string, limit int, recentFirst bool, userID string) ([]*gomatrixserverlib.HeaderedEvent, *util.JSONResponse) {
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children, err := db.ChildrenForParent(ctx, parentID, constRelType, recentFirst)
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if err != nil {
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util.GetLogger(ctx).WithError(err).Error("failed to get ChildrenForParent")
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resErr := jsonerror.InternalServerError()
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return nil, &resErr
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}
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var childEvents []*gomatrixserverlib.HeaderedEvent
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for _, child := range children {
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childEvent := getEventIfVisible(ctx, rsAPI, child.EventID, userID)
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if childEvent != nil {
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childEvents = append(childEvents, childEvent)
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}
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}
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if len(childEvents) > limit {
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return childEvents[:limit], nil
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}
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return childEvents, nil
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}
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// Begin to walk the thread DAG in the direction specified, either depth or breadth first according to the depth_first flag,
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// honouring the limit, max_depth and max_breadth values according to the following rules
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// nolint: unparam
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func walkThread(
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ctx context.Context, db Database, rsAPI roomserver.RoomserverInternalAPI, userID string, req *EventRelationshipRequest, included map[string]bool, limit int,
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) ([]*gomatrixserverlib.HeaderedEvent, bool) {
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if req.Direction != "down" {
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util.GetLogger(ctx).Error("not implemented: direction=up")
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return nil, false
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}
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var result []*gomatrixserverlib.HeaderedEvent
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eventWalker := walker{
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ctx: ctx,
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req: req,
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db: db,
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fn: func(wi *walkInfo) bool {
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// If already processed event, skip.
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if included[wi.EventID] {
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return false
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}
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// If the response array is >= limit, stop.
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if len(result) >= limit {
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return true
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}
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// Process the event.
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event := getEventIfVisible(ctx, rsAPI, wi.EventID, userID)
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if event != nil {
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result = append(result, event)
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}
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included[wi.EventID] = true
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return false
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},
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}
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limited, err := eventWalker.WalkFrom(req.EventID)
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if err != nil {
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util.GetLogger(ctx).WithError(err).Errorf("Failed to WalkFrom %s", req.EventID)
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}
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return result, limited
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}
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func getEventIfVisible(ctx context.Context, rsAPI roomserver.RoomserverInternalAPI, eventID, userID string) *gomatrixserverlib.HeaderedEvent {
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var queryEventsRes roomserver.QueryEventsByIDResponse
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err := rsAPI.QueryEventsByID(ctx, &roomserver.QueryEventsByIDRequest{
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EventIDs: []string{eventID},
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}, &queryEventsRes)
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if err != nil {
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util.GetLogger(ctx).WithError(err).Error("getEventIfVisible: failed to QueryEventsByID")
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return nil
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}
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if len(queryEventsRes.Events) == 0 {
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util.GetLogger(ctx).Infof("event does not exist")
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return nil // event does not exist
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}
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event := queryEventsRes.Events[0]
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// Allow events if the member is in the room
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// TODO: This does not honour history_visibility
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// TODO: This does not honour m.room.create content
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var queryMembershipRes roomserver.QueryMembershipForUserResponse
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err = rsAPI.QueryMembershipForUser(ctx, &roomserver.QueryMembershipForUserRequest{
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RoomID: event.RoomID(),
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UserID: userID,
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}, &queryMembershipRes)
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if err != nil {
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util.GetLogger(ctx).WithError(err).Error("getEventIfVisible: failed to QueryMembershipForUser")
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return nil
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}
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if !queryMembershipRes.IsInRoom {
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util.GetLogger(ctx).Infof("user not in room")
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return nil
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}
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return &event
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}
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type walkInfo struct {
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eventInfo
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SiblingNumber int
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Depth int
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}
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type walker struct {
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ctx context.Context
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req *EventRelationshipRequest
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db Database
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fn func(wi *walkInfo) bool // callback invoked for each event walked, return true to terminate the walk
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}
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// WalkFrom the event ID given
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func (w *walker) WalkFrom(eventID string) (limited bool, err error) {
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children, err := w.db.ChildrenForParent(w.ctx, eventID, constRelType, *w.req.RecentFirst)
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if err != nil {
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util.GetLogger(w.ctx).WithError(err).Error("WalkFrom() ChildrenForParent failed, cannot walk")
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return false, err
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}
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var next *walkInfo
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toWalk := w.addChildren(nil, children, 1)
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next, toWalk = w.nextChild(toWalk)
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for next != nil {
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stop := w.fn(next)
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if stop {
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return true, nil
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}
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// find the children's children
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children, err = w.db.ChildrenForParent(w.ctx, next.EventID, constRelType, *w.req.RecentFirst)
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if err != nil {
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util.GetLogger(w.ctx).WithError(err).Error("WalkFrom() ChildrenForParent failed, cannot walk")
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return false, err
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}
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toWalk = w.addChildren(toWalk, children, next.Depth+1)
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next, toWalk = w.nextChild(toWalk)
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}
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return false, nil
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}
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// addChildren adds an event's children to the to walk data structure
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func (w *walker) addChildren(toWalk []walkInfo, children []eventInfo, depthOfChildren int) []walkInfo {
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// Check what number child this event is (ordered by recent_first) compared to its parent, does it exceed (greater than) max_breadth? If yes, skip.
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if len(children) > w.req.MaxBreadth {
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children = children[:w.req.MaxBreadth]
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}
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// Check how deep the event is compared to event_id, does it exceed (greater than) max_depth? If yes, skip.
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if depthOfChildren > w.req.MaxDepth {
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return toWalk
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}
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if *w.req.DepthFirst {
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// the slice is a stack so push them in reverse order so we pop them in the correct order
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// e.g [3,2,1] => [3,2] , 1 => [3] , 2 => [] , 3
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for i := len(children) - 1; i >= 0; i-- {
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toWalk = append(toWalk, walkInfo{
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eventInfo: children[i],
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SiblingNumber: i + 1, // index from 1
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Depth: depthOfChildren,
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})
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}
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} else {
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// the slice is a queue so push them in normal order to we dequeue them in the correct order
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// e.g [1,2,3] => 1, [2, 3] => 2 , [3] => 3, []
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for i := range children {
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toWalk = append(toWalk, walkInfo{
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eventInfo: children[i],
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SiblingNumber: i + 1, // index from 1
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Depth: depthOfChildren,
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})
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}
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}
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return toWalk
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}
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func (w *walker) nextChild(toWalk []walkInfo) (*walkInfo, []walkInfo) {
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if len(toWalk) == 0 {
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return nil, nil
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}
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var child walkInfo
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if *w.req.DepthFirst {
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// toWalk is a stack so pop the child off
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child, toWalk = toWalk[len(toWalk)-1], toWalk[:len(toWalk)-1]
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return &child, toWalk
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}
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// toWalk is a queue so shift the child off
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child, toWalk = toWalk[0], toWalk[1:]
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return &child, toWalk
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}
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