Encode URLs properly (#728)

We were escaping the URL before performing any pattern matching on it.
This meant that if you sent data that URLdecoded to a "/", it would count as
a "/" in the URL, potentially causing a 404. This was causing some flaky tests
with some randomly-generated query parameters.

Now, we keep URLs encoded while doing the pattern matching, and only afterwards
do we URL decode each query parameter individually before passing them to their
respective handler functions.

github.com/gorilla/mux was also updated to v1.7.3 to fix a bug with URL encoding and subrouters.

1 files changed, 56 insertions, 13 deletions

diff --git a/federationapi/routing/routing.go b/federationapi/routing/routing.go
index 035d54aa..16704e0b 100644
--- a/federationapi/routing/routing.go
+++ b/federationapi/routing/routing.go
@@ -35,6 +35,10 @@ const (
 )
 
 // Setup registers HTTP handlers with the given ServeMux.
+//
+// Due to Setup being used to call many other functions, a gocyclo nolint is
+// applied:
+// nolint: gocyclo
 func Setup(
 	apiMux *mux.Router,
 	cfg config.Dendrite,
@@ -64,7 +68,10 @@ func Setup(
 	v1fedmux.Handle("/send/{txnID}/", common.MakeFedAPI(
 		"federation_send", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return Send(
 				httpReq, request, gomatrixserverlib.TransactionID(vars["txnID"]),
 				cfg, query, producer, keys, federation,
@@ -75,7 +82,10 @@ func Setup(
 	v1fedmux.Handle("/invite/{roomID}/{eventID}", common.MakeFedAPI(
 		"federation_invite", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return Invite(
 				httpReq, request, vars["roomID"], vars["eventID"],
 				cfg, producer, keys,
@@ -92,7 +102,10 @@ func Setup(
 	v1fedmux.Handle("/exchange_third_party_invite/{roomID}", common.MakeFedAPI(
 		"exchange_third_party_invite", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return ExchangeThirdPartyInvite(
 				httpReq, request, vars["roomID"], query, cfg, federation, producer,
 			)
@@ -102,7 +115,10 @@ func Setup(
 	v1fedmux.Handle("/event/{eventID}", common.MakeFedAPI(
 		"federation_get_event", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return GetEvent(
 				httpReq.Context(), request, query, vars["eventID"],
 			)
@@ -112,7 +128,10 @@ func Setup(
 	v1fedmux.Handle("/state/{roomID}", common.MakeFedAPI(
 		"federation_get_event_auth", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return GetState(
 				httpReq.Context(), request, query, vars["roomID"],
 			)
@@ -122,7 +141,10 @@ func Setup(
 	v1fedmux.Handle("/state_ids/{roomID}", common.MakeFedAPI(
 		"federation_get_event_auth", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return GetStateIDs(
 				httpReq.Context(), request, query, vars["roomID"],
 			)
@@ -150,7 +172,10 @@ func Setup(
 	v1fedmux.Handle("/user/devices/{userID}", common.MakeFedAPI(
 		"federation_user_devices", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return GetUserDevices(
 				httpReq, deviceDB, vars["userID"],
 			)
@@ -160,7 +185,10 @@ func Setup(
 	v1fedmux.Handle("/make_join/{roomID}/{userID}", common.MakeFedAPI(
 		"federation_make_join", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			roomID := vars["roomID"]
 			userID := vars["userID"]
 			return MakeJoin(
@@ -172,7 +200,10 @@ func Setup(
 	v1fedmux.Handle("/send_join/{roomID}/{userID}", common.MakeFedAPI(
 		"federation_send_join", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			roomID := vars["roomID"]
 			userID := vars["userID"]
 			return SendJoin(
@@ -184,7 +215,10 @@ func Setup(
 	v1fedmux.Handle("/make_leave/{roomID}/{userID}", common.MakeFedAPI(
 		"federation_make_leave", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			roomID := vars["roomID"]
 			userID := vars["userID"]
 			return MakeLeave(
@@ -196,7 +230,10 @@ func Setup(
 	v1fedmux.Handle("/send_leave/{roomID}/{userID}", common.MakeFedAPI(
 		"federation_send_leave", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			roomID := vars["roomID"]
 			userID := vars["userID"]
 			return SendLeave(
@@ -215,7 +252,10 @@ func Setup(
 	v1fedmux.Handle("/get_missing_events/{roomID}", common.MakeFedAPI(
 		"federation_get_missing_events", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return GetMissingEvents(httpReq, request, query, vars["roomID"])
 		},
 	)).Methods(http.MethodPost)
@@ -223,7 +263,10 @@ func Setup(
 	v1fedmux.Handle("/backfill/{roomID}/", common.MakeFedAPI(
 		"federation_backfill", cfg.Matrix.ServerName, keys,
 		func(httpReq *http.Request, request *gomatrixserverlib.FederationRequest) util.JSONResponse {
-			vars := mux.Vars(httpReq)
+			vars, err := common.URLDecodeMapValues(mux.Vars(httpReq))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
 			return Backfill(httpReq, request, query, vars["roomID"], cfg)
 		},
 	)).Methods(http.MethodGet)