Initial Store & Forward Implementation (#2917)

This adds store & forward relays into dendrite for p2p.
A few things have changed:
- new relay api serves new http endpoints for s&f federation
- updated outbound federation queueing which will attempt to forward
using s&f if appropriate
- database entries to track s&f relays for other nodes

relayapi/routing/routing.go

@@ -0,0 +1,123 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// 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 (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/getsentry/sentry-go"
+	"github.com/gorilla/mux"
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/internal/httputil"
+	relayInternal "github.com/matrix-org/dendrite/relayapi/internal"
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// Setup registers HTTP handlers with the given ServeMux.
+// The provided publicAPIMux MUST have `UseEncodedPath()` enabled or else routes will incorrectly
+// path unescape twice (once from the router, once from MakeRelayAPI). We need to have this enabled
+// so we can decode paths like foo/bar%2Fbaz as [foo, bar/baz] - by default it will decode to [foo, bar, baz]
+//
+// Due to Setup being used to call many other functions, a gocyclo nolint is
+// applied:
+// nolint: gocyclo
+func Setup(
+	fedMux *mux.Router,
+	cfg *config.FederationAPI,
+	relayAPI *relayInternal.RelayInternalAPI,
+	keys gomatrixserverlib.JSONVerifier,
+) {
+	v1fedmux := fedMux.PathPrefix("/v1").Subrouter()
+
+	v1fedmux.Handle("/send_relay/{txnID}/{userID}", MakeRelayAPI(
+		"send_relay_transaction", "", cfg.Matrix.IsLocalServerName, keys,
+		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest, vars map[string]string) util.JSONResponse {
+			userID, err := gomatrixserverlib.NewUserID(vars["userID"], false)
+			if err != nil {
+				return util.JSONResponse{
+					Code: http.StatusBadRequest,
+					JSON: jsonerror.InvalidUsername("Username was invalid"),
+				}
+			}
+			return SendTransactionToRelay(
+				httpReq, request, relayAPI, gomatrixserverlib.TransactionID(vars["txnID"]),
+				*userID,
+			)
+		},
+	)).Methods(http.MethodPut, http.MethodOptions)
+
+	v1fedmux.Handle("/relay_txn/{userID}", MakeRelayAPI(
+		"get_relay_transaction", "", cfg.Matrix.IsLocalServerName, keys,
+		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest, vars map[string]string) util.JSONResponse {
+			userID, err := gomatrixserverlib.NewUserID(vars["userID"], false)
+			if err != nil {
+				return util.JSONResponse{
+					Code: http.StatusBadRequest,
+					JSON: jsonerror.InvalidUsername("Username was invalid"),
+				}
+			}
+			return GetTransactionFromRelay(httpReq, request, relayAPI, *userID)
+		},
+	)).Methods(http.MethodGet, http.MethodOptions)
+}
+
+// MakeRelayAPI makes an http.Handler that checks matrix relay authentication.
+func MakeRelayAPI(
+	metricsName string, serverName gomatrixserverlib.ServerName,
+	isLocalServerName func(gomatrixserverlib.ServerName) bool,
+	keyRing gomatrixserverlib.JSONVerifier,
+	f func(*http.Request, *gomatrixserverlib.FederationRequest, map[string]string) util.JSONResponse,
+) http.Handler {
+	h := func(req *http.Request) util.JSONResponse {
+		fedReq, errResp := gomatrixserverlib.VerifyHTTPRequest(
+			req, time.Now(), serverName, isLocalServerName, keyRing,
+		)
+		if fedReq == nil {
+			return errResp
+		}
+		// add the user to Sentry, if enabled
+		hub := sentry.GetHubFromContext(req.Context())
+		if hub != nil {
+			hub.Scope().SetTag("origin", string(fedReq.Origin()))
+			hub.Scope().SetTag("uri", fedReq.RequestURI())
+		}
+		defer func() {
+			if r := recover(); r != nil {
+				if hub != nil {
+					hub.CaptureException(fmt.Errorf("%s panicked", req.URL.Path))
+				}
+				// re-panic to return the 500
+				panic(r)
+			}
+		}()
+		vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+		if err != nil {
+			return util.MatrixErrorResponse(400, "M_UNRECOGNISED", "badly encoded query params")
+		}
+
+		jsonRes := f(req, fedReq, vars)
+		// do not log 4xx as errors as they are client fails, not server fails
+		if hub != nil && jsonRes.Code >= 500 {
+			hub.Scope().SetExtra("response", jsonRes)
+			hub.CaptureException(fmt.Errorf("%s returned HTTP %d", req.URL.Path, jsonRes.Code))
+		}
+		return jsonRes
+	}
+	return httputil.MakeExternalAPI(metricsName, h)
+}