dendrite/roomserver/internal/helpers/helpers.go
Kegsay a846dad0e1
Return what we have when we encounter missing events when servicing backfill/gme (#1499)
We expect to have missing events as we walk back in the DAG over federation
as we didn't always create the room. When checking if the server is allowed
to see those events, just give up and stop rather than fail the request.
2020-10-08 12:22:00 +01:00

387 lines
12 KiB
Go

package helpers
import (
"context"
"database/sql"
"errors"
"fmt"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/dendrite/roomserver/auth"
"github.com/matrix-org/dendrite/roomserver/state"
"github.com/matrix-org/dendrite/roomserver/storage"
"github.com/matrix-org/dendrite/roomserver/storage/shared"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
)
// TODO: temporary package which has helper functions used by both internal/perform packages.
// Move these to a more sensible place.
func UpdateToInviteMembership(
mu *shared.MembershipUpdater, add *gomatrixserverlib.Event, updates []api.OutputEvent,
roomVersion gomatrixserverlib.RoomVersion,
) ([]api.OutputEvent, error) {
// We may have already sent the invite to the user, either because we are
// reprocessing this event, or because the we received this invite from a
// remote server via the federation invite API. In those cases we don't need
// to send the event.
needsSending, err := mu.SetToInvite(*add)
if err != nil {
return nil, err
}
if needsSending {
// We notify the consumers using a special event even though we will
// notify them about the change in current state as part of the normal
// room event stream. This ensures that the consumers only have to
// consider a single stream of events when determining whether a user
// is invited, rather than having to combine multiple streams themselves.
onie := api.OutputNewInviteEvent{
Event: add.Headered(roomVersion),
RoomVersion: roomVersion,
}
updates = append(updates, api.OutputEvent{
Type: api.OutputTypeNewInviteEvent,
NewInviteEvent: &onie,
})
}
return updates, nil
}
func IsServerCurrentlyInRoom(ctx context.Context, db storage.Database, serverName gomatrixserverlib.ServerName, roomID string) (bool, error) {
info, err := db.RoomInfo(ctx, roomID)
if err != nil {
return false, err
}
if info == nil {
return false, fmt.Errorf("unknown room %s", roomID)
}
eventNIDs, err := db.GetMembershipEventNIDsForRoom(ctx, info.RoomNID, true, false)
if err != nil {
return false, err
}
events, err := db.Events(ctx, eventNIDs)
if err != nil {
return false, err
}
gmslEvents := make([]gomatrixserverlib.Event, len(events))
for i := range events {
gmslEvents[i] = events[i].Event
}
return auth.IsAnyUserOnServerWithMembership(serverName, gmslEvents, gomatrixserverlib.Join), nil
}
func IsInvitePending(
ctx context.Context, db storage.Database,
roomID, userID string,
) (bool, string, string, error) {
// Look up the room NID for the supplied room ID.
info, err := db.RoomInfo(ctx, roomID)
if err != nil {
return false, "", "", fmt.Errorf("r.DB.RoomInfo: %w", err)
}
if info == nil {
return false, "", "", fmt.Errorf("cannot get RoomInfo: unknown room ID %s", roomID)
}
// Look up the state key NID for the supplied user ID.
targetUserNIDs, err := db.EventStateKeyNIDs(ctx, []string{userID})
if err != nil {
return false, "", "", fmt.Errorf("r.DB.EventStateKeyNIDs: %w", err)
}
targetUserNID, targetUserFound := targetUserNIDs[userID]
if !targetUserFound {
return false, "", "", fmt.Errorf("missing NID for user %q (%+v)", userID, targetUserNIDs)
}
// Let's see if we have an event active for the user in the room. If
// we do then it will contain a server name that we can direct the
// send_leave to.
senderUserNIDs, eventIDs, err := db.GetInvitesForUser(ctx, info.RoomNID, targetUserNID)
if err != nil {
return false, "", "", fmt.Errorf("r.DB.GetInvitesForUser: %w", err)
}
if len(senderUserNIDs) == 0 {
return false, "", "", nil
}
userNIDToEventID := make(map[types.EventStateKeyNID]string)
for i, nid := range senderUserNIDs {
userNIDToEventID[nid] = eventIDs[i]
}
// Look up the user ID from the NID.
senderUsers, err := db.EventStateKeys(ctx, senderUserNIDs)
if err != nil {
return false, "", "", fmt.Errorf("r.DB.EventStateKeys: %w", err)
}
if len(senderUsers) == 0 {
return false, "", "", fmt.Errorf("no senderUsers")
}
senderUser, senderUserFound := senderUsers[senderUserNIDs[0]]
if !senderUserFound {
return false, "", "", fmt.Errorf("missing user for NID %d (%+v)", senderUserNIDs[0], senderUsers)
}
return true, senderUser, userNIDToEventID[senderUserNIDs[0]], nil
}
// GetMembershipsAtState filters the state events to
// only keep the "m.room.member" events with a "join" membership. These events are returned.
// Returns an error if there was an issue fetching the events.
func GetMembershipsAtState(
ctx context.Context, db storage.Database, stateEntries []types.StateEntry, joinedOnly bool,
) ([]types.Event, error) {
var eventNIDs []types.EventNID
for _, entry := range stateEntries {
// Filter the events to retrieve to only keep the membership events
if entry.EventTypeNID == types.MRoomMemberNID {
eventNIDs = append(eventNIDs, entry.EventNID)
}
}
// Get all of the events in this state
stateEvents, err := db.Events(ctx, eventNIDs)
if err != nil {
return nil, err
}
if !joinedOnly {
return stateEvents, nil
}
// Filter the events to only keep the "join" membership events
var events []types.Event
for _, event := range stateEvents {
membership, err := event.Membership()
if err != nil {
return nil, err
}
if membership == gomatrixserverlib.Join {
events = append(events, event)
}
}
return events, nil
}
func StateBeforeEvent(ctx context.Context, db storage.Database, info types.RoomInfo, eventNID types.EventNID) ([]types.StateEntry, error) {
roomState := state.NewStateResolution(db, info)
// Lookup the event NID
eIDs, err := db.EventIDs(ctx, []types.EventNID{eventNID})
if err != nil {
return nil, err
}
eventIDs := []string{eIDs[eventNID]}
prevState, err := db.StateAtEventIDs(ctx, eventIDs)
if err != nil {
return nil, err
}
// Fetch the state as it was when this event was fired
return roomState.LoadCombinedStateAfterEvents(ctx, prevState)
}
func LoadEvents(
ctx context.Context, db storage.Database, eventNIDs []types.EventNID,
) ([]gomatrixserverlib.Event, error) {
stateEvents, err := db.Events(ctx, eventNIDs)
if err != nil {
return nil, err
}
result := make([]gomatrixserverlib.Event, len(stateEvents))
for i := range stateEvents {
result[i] = stateEvents[i].Event
}
return result, nil
}
func LoadStateEvents(
ctx context.Context, db storage.Database, stateEntries []types.StateEntry,
) ([]gomatrixserverlib.Event, error) {
eventNIDs := make([]types.EventNID, len(stateEntries))
for i := range stateEntries {
eventNIDs[i] = stateEntries[i].EventNID
}
return LoadEvents(ctx, db, eventNIDs)
}
func CheckServerAllowedToSeeEvent(
ctx context.Context, db storage.Database, info types.RoomInfo, eventID string, serverName gomatrixserverlib.ServerName, isServerInRoom bool,
) (bool, error) {
roomState := state.NewStateResolution(db, info)
stateEntries, err := roomState.LoadStateAtEvent(ctx, eventID)
if err != nil {
if errors.Is(err, sql.ErrNoRows) {
return false, nil
}
return false, err
}
// TODO: We probably want to make it so that we don't have to pull
// out all the state if possible.
stateAtEvent, err := LoadStateEvents(ctx, db, stateEntries)
if err != nil {
return false, err
}
return auth.IsServerAllowed(serverName, isServerInRoom, stateAtEvent), nil
}
// TODO: Remove this when we have tests to assert correctness of this function
// nolint:gocyclo
func ScanEventTree(
ctx context.Context, db storage.Database, info types.RoomInfo, front []string, visited map[string]bool, limit int,
serverName gomatrixserverlib.ServerName,
) ([]types.EventNID, error) {
var resultNIDs []types.EventNID
var err error
var allowed bool
var events []types.Event
var next []string
var pre string
// TODO: add tests for this function to ensure it meets the contract that callers expect (and doc what that is supposed to be)
// Currently, callers like PerformBackfill will call scanEventTree with a pre-populated `visited` map, assuming that by doing
// so means that the events in that map will NOT be returned from this function. That is not currently true, resulting in
// duplicate events being sent in response to /backfill requests.
initialIgnoreList := make(map[string]bool, len(visited))
for k, v := range visited {
initialIgnoreList[k] = v
}
resultNIDs = make([]types.EventNID, 0, limit)
var checkedServerInRoom bool
var isServerInRoom bool
// Loop through the event IDs to retrieve the requested events and go
// through the whole tree (up to the provided limit) using the events'
// "prev_event" key.
BFSLoop:
for len(front) > 0 {
// Prevent unnecessary allocations: reset the slice only when not empty.
if len(next) > 0 {
next = make([]string, 0)
}
// Retrieve the events to process from the database.
events, err = db.EventsFromIDs(ctx, front)
if err != nil {
return resultNIDs, err
}
if !checkedServerInRoom && len(events) > 0 {
// It's nasty that we have to extract the room ID from an event, but many federation requests
// only talk in event IDs, no room IDs at all (!!!)
ev := events[0]
isServerInRoom, err = IsServerCurrentlyInRoom(ctx, db, serverName, ev.RoomID())
if err != nil {
util.GetLogger(ctx).WithError(err).Error("Failed to check if server is currently in room, assuming not.")
}
checkedServerInRoom = true
}
for _, ev := range events {
// Break out of the loop if the provided limit is reached.
if len(resultNIDs) == limit {
break BFSLoop
}
if !initialIgnoreList[ev.EventID()] {
// Update the list of events to retrieve.
resultNIDs = append(resultNIDs, ev.EventNID)
}
// Loop through the event's parents.
for _, pre = range ev.PrevEventIDs() {
// Only add an event to the list of next events to process if it
// hasn't been seen before.
if !visited[pre] {
visited[pre] = true
allowed, err = CheckServerAllowedToSeeEvent(ctx, db, info, pre, serverName, isServerInRoom)
if err != nil {
util.GetLogger(ctx).WithField("server", serverName).WithField("event_id", pre).WithError(err).Error(
"Error checking if allowed to see event",
)
// drop the error, as we will often error at the DB level if we don't have the prev_event itself. Let's
// just return what we have.
return resultNIDs, nil
}
// If the event hasn't been seen before and the HS
// requesting to retrieve it is allowed to do so, add it to
// the list of events to retrieve.
if allowed {
next = append(next, pre)
} else {
util.GetLogger(ctx).WithField("server", serverName).WithField("event_id", pre).Info("Not allowed to see event")
}
}
}
}
// Repeat the same process with the parent events we just processed.
front = next
}
return resultNIDs, err
}
func QueryLatestEventsAndState(
ctx context.Context, db storage.Database,
request *api.QueryLatestEventsAndStateRequest,
response *api.QueryLatestEventsAndStateResponse,
) error {
roomInfo, err := db.RoomInfo(ctx, request.RoomID)
if err != nil {
return err
}
if roomInfo == nil || roomInfo.IsStub {
response.RoomExists = false
return nil
}
roomState := state.NewStateResolution(db, *roomInfo)
response.RoomExists = true
response.RoomVersion = roomInfo.RoomVersion
var currentStateSnapshotNID types.StateSnapshotNID
response.LatestEvents, currentStateSnapshotNID, response.Depth, err =
db.LatestEventIDs(ctx, roomInfo.RoomNID)
if err != nil {
return err
}
var stateEntries []types.StateEntry
if len(request.StateToFetch) == 0 {
// Look up all room state.
stateEntries, err = roomState.LoadStateAtSnapshot(
ctx, currentStateSnapshotNID,
)
} else {
// Look up the current state for the requested tuples.
stateEntries, err = roomState.LoadStateAtSnapshotForStringTuples(
ctx, currentStateSnapshotNID, request.StateToFetch,
)
}
if err != nil {
return err
}
stateEvents, err := LoadStateEvents(ctx, db, stateEntries)
if err != nil {
return err
}
for _, event := range stateEvents {
response.StateEvents = append(response.StateEvents, event.Headered(roomInfo.RoomVersion))
}
return nil
}