Add support for receiving room events over federation. (#130)

* Add API for querying events by ID.

* Fix tense

* Start implementing federation ingress

* More stuff

* Hook up federation event receiving

* Handle the case where we are missing state

* Fix docstring and comments

* Fix infinite loop when printing unknownRoomError

src/github.com/matrix-org/dendrite/cmd/dendrite-federation-api-server/main.go

@@ -18,11 +18,14 @@ import (
 	"encoding/base64"
 	"net/http"
 	"os"
+	"strings"
 	"time"
 
+	"github.com/matrix-org/dendrite/clientapi/producers"
 	"github.com/matrix-org/dendrite/common"
 	"github.com/matrix-org/dendrite/federationapi/config"
 	"github.com/matrix-org/dendrite/federationapi/routing"
+	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
 
 	log "github.com/Sirupsen/logrus"
@@ -41,6 +44,9 @@ var (
 	//     python -c 'print raw_input()[19:].replace(":","").decode("hex").encode("base64").rstrip("=\n")'
 	//
 	tlsFingerprint       = os.Getenv("TLS_FINGERPRINT")
+	kafkaURIs            = strings.Split(os.Getenv("KAFKA_URIS"), ",")
+	roomserverURL        = os.Getenv("ROOMSERVER_URL")
+	roomserverInputTopic = os.Getenv("TOPIC_INPUT_ROOM_EVENT")
 )
 
 func main() {
@@ -57,6 +63,18 @@ func main() {
 		log.Panic("No TLS_FINGERPRINT environment variable found.")
 	}
 
+	if len(kafkaURIs) == 0 {
+		// the kafka default is :9092
+		kafkaURIs = []string{"localhost:9092"}
+	}
+
+	if roomserverURL == "" {
+		log.Panic("No ROOMSERVER_URL environment variable found.")
+	}
+
+	if roomserverInputTopic == "" {
+		log.Panic("No TOPIC_INPUT_ROOM_EVENT environment variable found. This should match the roomserver input topic.")
+	}
 	cfg := config.FederationAPI{
 		ServerName: serverName,
 		// TODO: make the validity period configurable.
@@ -75,6 +93,37 @@ func main() {
 	}
 	cfg.TLSFingerPrints = []gomatrixserverlib.TLSFingerprint{{fingerprintSHA256}}
 
-	routing.Setup(http.DefaultServeMux, cfg)
+	federation := gomatrixserverlib.NewFederationClient(cfg.ServerName, cfg.KeyID, cfg.PrivateKey)
+
+	keyRing := gomatrixserverlib.KeyRing{
+		KeyFetchers: []gomatrixserverlib.KeyFetcher{
+			// TODO: Use perspective key fetchers for production.
+			&gomatrixserverlib.DirectKeyFetcher{federation.Client},
+		},
+		KeyDatabase: &dummyKeyDatabase{},
+	}
+	queryAPI := api.NewRoomserverQueryAPIHTTP(roomserverURL, nil)
+
+	roomserverProducer, err := producers.NewRoomserverProducer(kafkaURIs, roomserverInputTopic)
+	if err != nil {
+		log.Panicf("Failed to setup kafka producers(%s): %s", kafkaURIs, err)
+	}
+
+	routing.Setup(http.DefaultServeMux, cfg, queryAPI, roomserverProducer, keyRing, federation)
 	log.Fatal(http.ListenAndServe(bindAddr, nil))
 }
+
+// TODO: Implement a proper key database.
+type dummyKeyDatabase struct{}
+
+func (d *dummyKeyDatabase) FetchKeys(
+	requests map[gomatrixserverlib.PublicKeyRequest]gomatrixserverlib.Timestamp,
+) (map[gomatrixserverlib.PublicKeyRequest]gomatrixserverlib.ServerKeys, error) {
+	return nil, nil
+}
+
+func (d *dummyKeyDatabase) StoreKeys(
+	map[gomatrixserverlib.PublicKeyRequest]gomatrixserverlib.ServerKeys,
+) error {
+	return nil
+}

src/github.com/matrix-org/dendrite/cmd/federation-api-proxy/main.go

@@ -0,0 +1,124 @@
+// Copyright 2017 Vector Creations 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 main
+
+import (
+	"flag"
+	"fmt"
+	log "github.com/Sirupsen/logrus"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+	"strings"
+	"time"
+)
+
+const usage = `Usage: %s
+
+Create a single endpoint URL which remote matrix servers can be pointed at.
+
+The server-server API in Dendrite is split across multiple processes
+which listen on multiple ports. You cannot point a Matrix server at
+any of those ports, as there will be unimplemented functionality.
+In addition, all server-server API processes start with the additional
+path prefix '/api', which Matrix servers will be unaware of.
+
+This tool will proxy requests for all server-server URLs and forward
+them to their respective process. It will also add the '/api' path
+prefix to incoming requests.
+
+THIS TOOL IS FOR TESTING AND NOT INTENDED FOR PRODUCTION USE.
+
+Arguments:
+
+`
+
+var (
+	federationAPIURL = flag.String("federation-api-url", "", "The base URL of the listening 'dendrite-federation-api-server' process. E.g. 'http://localhost:4200'")
+	bindAddress      = flag.String("bind-address", ":8448", "The listening port for the proxy.")
+	certFile         = flag.String("tls-cert", "server.crt", "The PEM formatted X509 certificate to use for TLS")
+	keyFile          = flag.String("tls-key", "server.key", "The PEM private key to use for TLS")
+)
+
+func makeProxy(targetURL string) (*httputil.ReverseProxy, error) {
+	if !strings.HasSuffix(targetURL, "/") {
+		targetURL += "/"
+	}
+	// Check that we can parse the URL.
+	_, err := url.Parse(targetURL)
+	if err != nil {
+		return nil, err
+	}
+	return &httputil.ReverseProxy{
+		Director: func(req *http.Request) {
+			// URL.Path() removes the % escaping from the path.
+			// The % encoding will be added back when the url is encoded
+			// when the request is forwarded.
+			// This means that we will lose any unessecary escaping from the URL.
+			// Pratically this means that any distinction between '%2F' and '/'
+			// in the URL will be lost by the time it reaches the target.
+			path := req.URL.Path
+			path = "api" + path
+			log.WithFields(log.Fields{
+				"path":   path,
+				"url":    targetURL,
+				"method": req.Method,
+			}).Print("proxying request")
+			newURL, err := url.Parse(targetURL + path)
+			if err != nil {
+				// We already checked that we can parse the URL
+				// So this shouldn't ever get hit.
+				panic(err)
+			}
+			// Copy the query parameters from the request.
+			newURL.RawQuery = req.URL.RawQuery
+			req.URL = newURL
+		},
+	}, nil
+}
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, usage, os.Args[0])
+		flag.PrintDefaults()
+	}
+
+	flag.Parse()
+
+	if *federationAPIURL == "" {
+		flag.Usage()
+		fmt.Fprintln(os.Stderr, "no --federation-api-url specified.")
+		os.Exit(1)
+	}
+
+	federationProxy, err := makeProxy(*federationAPIURL)
+	if err != nil {
+		panic(err)
+	}
+
+	http.Handle("/", federationProxy)
+
+	srv := &http.Server{
+		Addr:         *bindAddress,
+		ReadTimeout:  1 * time.Minute, // how long we wait for the client to send the entire request (after connection accept)
+		WriteTimeout: 5 * time.Minute, // how long the proxy has to write the full response
+	}
+
+	fmt.Println("Proxying requests to:")
+	fmt.Println("  /*                       => ", *federationAPIURL+"/api/*")
+	fmt.Println("Listening on ", *bindAddress)
+	panic(srv.ListenAndServeTLS(*certFile, *keyFile))
+}

src/github.com/matrix-org/dendrite/federationapi/routing/routing.go

@@ -16,21 +16,35 @@ package routing
 
 import (
 	"github.com/gorilla/mux"
+	"github.com/matrix-org/dendrite/clientapi/producers"
 	"github.com/matrix-org/dendrite/federationapi/config"
 	"github.com/matrix-org/dendrite/federationapi/readers"
+	"github.com/matrix-org/dendrite/federationapi/writers"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
 	"github.com/prometheus/client_golang/prometheus"
 	"net/http"
+	"time"
 )
 
 const (
 	pathPrefixV2Keys       = "/_matrix/key/v2"
+	pathPrefixV1Federation = "/_matrix/federation/v1"
 )
 
 // Setup registers HTTP handlers with the given ServeMux.
-func Setup(servMux *http.ServeMux, cfg config.FederationAPI) {
+func Setup(
+	servMux *http.ServeMux,
+	cfg config.FederationAPI,
+	query api.RoomserverQueryAPI,
+	producer *producers.RoomserverProducer,
+	keys gomatrixserverlib.KeyRing,
+	federation *gomatrixserverlib.FederationClient,
+) {
 	apiMux := mux.NewRouter()
 	v2keysmux := apiMux.PathPrefix(pathPrefixV2Keys).Subrouter()
+	v1fedmux := apiMux.PathPrefix(pathPrefixV1Federation).Subrouter()
 
 	localKeys := makeAPI("localkeys", func(req *http.Request) util.JSONResponse {
 		return readers.LocalKeys(req, cfg)
@@ -43,6 +57,17 @@ func Setup(servMux *http.ServeMux, cfg config.FederationAPI) {
 	v2keysmux.Handle("/server/{keyID}", localKeys)
 	v2keysmux.Handle("/server/", localKeys)
 
+	v1fedmux.Handle("/send/{txnID}/", makeAPI("send",
+		func(req *http.Request) util.JSONResponse {
+			vars := mux.Vars(req)
+			return writers.Send(
+				req, gomatrixserverlib.TransactionID(vars["txnID"]),
+				time.Now(),
+				cfg, query, producer, keys, federation,
+			)
+		},
+	))
+
 	servMux.Handle("/metrics", prometheus.Handler())
 	servMux.Handle("/api/", http.StripPrefix("/api", apiMux))
 }

src/github.com/matrix-org/dendrite/federationapi/writers/send.go

@@ -0,0 +1,211 @@
+package writers
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/matrix-org/dendrite/clientapi/httputil"
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/clientapi/producers"
+	"github.com/matrix-org/dendrite/federationapi/config"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+	"net/http"
+	"time"
+)
+
+// Send implements /_matrix/federation/v1/send/{txnID}
+func Send(
+	req *http.Request,
+	txnID gomatrixserverlib.TransactionID,
+	now time.Time,
+	cfg config.FederationAPI,
+	query api.RoomserverQueryAPI,
+	producer *producers.RoomserverProducer,
+	keys gomatrixserverlib.KeyRing,
+	federation *gomatrixserverlib.FederationClient,
+) util.JSONResponse {
+	request, errResp := gomatrixserverlib.VerifyHTTPRequest(req, now, cfg.ServerName, keys)
+	if request == nil {
+		return errResp
+	}
+
+	t := txnReq{
+		query:      query,
+		producer:   producer,
+		keys:       keys,
+		federation: federation,
+	}
+	if err := json.Unmarshal(request.Content(), &t); err != nil {
+		return util.JSONResponse{
+			Code: 400,
+			JSON: jsonerror.BadJSON("The request body could not be decoded into valid JSON. " + err.Error()),
+		}
+	}
+
+	t.Origin = request.Origin()
+	t.TransactionID = txnID
+	t.Destination = cfg.ServerName
+
+	resp, err := t.processTransaction()
+	if err != nil {
+		return httputil.LogThenError(req, err)
+	}
+
+	return util.JSONResponse{
+		Code: 200,
+		JSON: resp,
+	}
+}
+
+type txnReq struct {
+	gomatrixserverlib.Transaction
+	query      api.RoomserverQueryAPI
+	producer   *producers.RoomserverProducer
+	keys       gomatrixserverlib.KeyRing
+	federation *gomatrixserverlib.FederationClient
+}
+
+func (t *txnReq) processTransaction() (*gomatrixserverlib.RespSend, error) {
+	// Check the event signatures
+	if err := gomatrixserverlib.VerifyEventSignatures(t.PDUs, t.keys); err != nil {
+		return nil, err
+	}
+
+	// Process the events.
+	results := map[string]gomatrixserverlib.PDUResult{}
+	for _, e := range t.PDUs {
+		err := t.processEvent(e)
+		if err != nil {
+			// If the error is due to the event itself being bad then we skip
+			// it and move onto the next event. We report an error so that the
+			// sender knows that we have skipped processing it.
+			//
+			// However if the event is due to a temporary failure in our server
+			// such as a database being unavailable then we should bail, and
+			// hope that the sender will retry when we are feeling better.
+			//
+			// It is uncertain what we should do if an event fails because
+			// we failed to fetch more information from the sending server.
+			// For example if a request to /state fails.
+			// If we skip the event then we risk missing the event until we
+			// receive another event referencing it.
+			// If we bail and stop processing then we risk wedging incoming
+			// transactions from that server forever.
+			switch err.(type) {
+			case unknownRoomError:
+			case *gomatrixserverlib.NotAllowed:
+			default:
+				// Any other error should be the result of a temporary error in
+				// our server so we should bail processing the transaction entirely.
+				return nil, err
+			}
+			results[e.EventID()] = gomatrixserverlib.PDUResult{err.Error()}
+		} else {
+			results[e.EventID()] = gomatrixserverlib.PDUResult{}
+		}
+	}
+
+	// TODO: Process the EDUs.
+
+	return &gomatrixserverlib.RespSend{PDUs: results}, nil
+}
+
+type unknownRoomError struct {
+	roomID string
+}
+
+func (e unknownRoomError) Error() string { return fmt.Sprintf("unknown room %q", e.roomID) }
+
+func (t *txnReq) processEvent(e gomatrixserverlib.Event) error {
+	refs := e.PrevEvents()
+	prevEventIDs := make([]string, len(refs))
+	for i := range refs {
+		prevEventIDs[i] = refs[i].EventID
+	}
+
+	// Fetch the state needed to authenticate the event.
+	needed := gomatrixserverlib.StateNeededForAuth([]gomatrixserverlib.Event{e})
+	stateReq := api.QueryStateAfterEventsRequest{
+		RoomID:       e.RoomID(),
+		PrevEventIDs: prevEventIDs,
+		StateToFetch: needed.Tuples(),
+	}
+	var stateResp api.QueryStateAfterEventsResponse
+	if err := t.query.QueryStateAfterEvents(&stateReq, &stateResp); err != nil {
+		return err
+	}
+
+	if !stateResp.RoomExists {
+		// TODO: When synapse receives a message for a room it is not in it
+		// asks the remote server for the state of the room so that it can
+		// check if the remote server knows of a join "m.room.member" event
+		// that this server is unaware of.
+		// However generally speaking we should reject events for rooms we
+		// aren't a member of.
+		return unknownRoomError{e.RoomID()}
+	}
+
+	if !stateResp.PrevEventsExist {
+		return t.processEventWithMissingState(e)
+	}
+
+	// Check that the event is allowed by the state at the event.
+	if err := checkAllowedByState(e, stateResp.StateEvents); err != nil {
+		return err
+	}
+
+	// TODO: Check that the roomserver has a copy of all of the auth_events.
+	// TODO: Check that the event is allowed by its auth_events.
+
+	// pass the event to the roomserver
+	if err := t.producer.SendEvents([]gomatrixserverlib.Event{e}); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func checkAllowedByState(e gomatrixserverlib.Event, stateEvents []gomatrixserverlib.Event) error {
+	authUsingState := gomatrixserverlib.NewAuthEvents(nil)
+	for i := range stateEvents {
+		authUsingState.AddEvent(&stateEvents[i])
+	}
+	return gomatrixserverlib.Allowed(e, &authUsingState)
+}
+
+func (t *txnReq) processEventWithMissingState(e gomatrixserverlib.Event) error {
+	// We are missing the previous events for this events.
+	// This means that there is a gap in our view of the history of the
+	// room. There two ways that we can handle such a gap:
+	//   1) We can fill in the gap using /get_missing_events
+	//   2) We can leave the gap and request the state of the room at
+	//      this event from the remote server using either /state_ids
+	//      or /state.
+	// Synapse will attempt to do 1 and if that fails or if the gap is
+	// too large then it will attempt 2.
+	// Synapse will use /state_ids if possible since ususally the state
+	// is largely unchanged and it is more efficient to fetch a list of
+	// event ids and then use /event to fetch the individual events.
+	// However not all version of synapse support /state_ids so you may
+	// need to fallback to /state.
+	// TODO: Attempt to fill in the gap using /get_missing_events
+	// TODO: Attempt to fetch the state using /state_ids and /events
+	state, err := t.federation.LookupState(t.Origin, e.RoomID(), e.EventID())
+	if err != nil {
+		return err
+	}
+	// Check that the returned state is valid.
+	if err := state.Check(t.keys); err != nil {
+		return err
+	}
+	// Check that the event is allowed by the state.
+	if err := checkAllowedByState(e, state.StateEvents); err != nil {
+		return err
+	}
+	// pass the event along with the state to the roomserver
+	if err := t.producer.SendEventWithState(state, e); err != nil {
+		return err
+	}
+	return nil
+}

src/github.com/matrix-org/dendrite/roomserver/input/events.go

@@ -28,7 +28,7 @@ type RoomEventDatabase interface {
 	StoreEvent(event gomatrixserverlib.Event, authEventNIDs []types.EventNID) (types.RoomNID, types.StateAtEvent, error)
 	// Lookup the state entries for a list of string event IDs
 	// Returns an error if the there is an error talking to the database
-	// or if the event IDs aren't in the database.
+	// Returns a types.MissingEventError if the event IDs aren't in the database.
 	StateEntriesForEventIDs(eventIDs []string) ([]types.StateEntry, error)
 	// Set the state at an event.
 	SetState(eventNID types.EventNID, stateNID types.StateSnapshotNID) error

src/github.com/matrix-org/dendrite/roomserver/query/query.go

@@ -97,10 +97,13 @@ func (r *RoomserverQueryAPI) QueryStateAfterEvents(
 
 	prevStates, err := r.DB.StateAtEventIDs(request.PrevEventIDs)
 	if err != nil {
-		// TODO: Check if the error was because we are missing events from the
-		// database or are missing state at events from the database.
+		switch err.(type) {
+		case types.MissingEventError:
+			return nil
+		default:
 			return err
 		}
+	}
 	response.PrevEventsExist = true
 
 	// Lookup the currrent state for the requested tuples.

src/github.com/matrix-org/dendrite/roomserver/state/state.go

@@ -32,7 +32,7 @@ type RoomStateDatabase interface {
 	AddState(roomNID types.RoomNID, stateBlockNIDs []types.StateBlockNID, state []types.StateEntry) (types.StateSnapshotNID, error)
 	// Lookup the state of a room at each event for a list of string event IDs.
 	// Returns an error if there is an error talking to the database
-	// or if the room state for the event IDs aren't in the database
+	// Returns a types.MissingEventError if the room state for the event IDs aren't in the database
 	StateAtEventIDs(eventIDs []string) ([]types.StateAtEvent, error)
 	// Lookup the numeric IDs for a list of string event types.
 	// Returns a map from string event type to numeric ID for the event type.

src/github.com/matrix-org/dendrite/roomserver/storage/events_table.go

@@ -166,6 +166,8 @@ func (s *eventStatements) selectEvent(eventID string) (types.EventNID, types.Sta
 	return types.EventNID(eventNID), types.StateSnapshotNID(stateNID), err
 }
 
+// bulkSelectStateEventByID lookups a list of state events by event ID.
+// If any of the requested events are missing from the database it returns a types.MissingEventError
 func (s *eventStatements) bulkSelectStateEventByID(eventIDs []string) ([]types.StateEntry, error) {
 	rows, err := s.bulkSelectStateEventByIDStmt.Query(pq.StringArray(eventIDs))
 	if err != nil {
@@ -194,11 +196,16 @@ func (s *eventStatements) bulkSelectStateEventByID(eventIDs []string) ([]types.S
 		// However it should be possible debug this by replaying queries or entries from the input kafka logs.
 		// If this turns out to be impossible and we do need the debug information here, it would be better
 		// to do it as a separate query rather than slowing down/complicating the common case.
-		return nil, fmt.Errorf("storage: state event IDs missing from the database (%d != %d)", i, len(eventIDs))
+		return nil, types.MissingEventError(
+			fmt.Sprintf("storage: state event IDs missing from the database (%d != %d)", i, len(eventIDs)),
+		)
 	}
 	return results, err
 }
 
+// bulkSelectStateAtEventByID lookups the state at a list of events by event ID.
+// If any of the requested events are missing from the database it returns a types.MissingEventError.
+// If we do not have the state for any of the requested events it returns a types.MissingEventError.
 func (s *eventStatements) bulkSelectStateAtEventByID(eventIDs []string) ([]types.StateAtEvent, error) {
 	rows, err := s.bulkSelectStateAtEventByIDStmt.Query(pq.StringArray(eventIDs))
 	if err != nil {
@@ -218,11 +225,15 @@ func (s *eventStatements) bulkSelectStateAtEventByID(eventIDs []string) ([]types
 			return nil, err
 		}
 		if result.BeforeStateSnapshotNID == 0 {
-			return nil, fmt.Errorf("storage: missing state for event NID %d", result.EventNID)
+			return nil, types.MissingEventError(
+				fmt.Sprintf("storage: missing state for event NID %d", result.EventNID),
+			)
 		}
 	}
 	if i != len(eventIDs) {
-		return nil, fmt.Errorf("storage: event IDs missing from the database (%d != %d)", i, len(eventIDs))
+		return nil, types.MissingEventError(
+			fmt.Sprintf("storage: event IDs missing from the database (%d != %d)", i, len(eventIDs)),
+		)
 	}
 	return results, err
 }

src/github.com/matrix-org/dendrite/roomserver/types/types.go

@@ -168,3 +168,9 @@ type RoomRecentEventsUpdater interface {
 	// Rollback the transaction.
 	Rollback() error
 }
+
+// A MissingEventError is an error that happened because the roomserver was
+// missing requested events from its database.
+type MissingEventError string
+
+func (e MissingEventError) Error() string { return string(e) }