Add PerformInvite and refactor how errors get handled (#1158)

* Add PerformInvite and refactor how errors get handled

- Rename `JoinError` to `PerformError`
- Remove `error` from the API function signature entirely. This forces
  errors to be bundled into `PerformError` which makes it easier for callers
  to detect and handle errors. On network errors, HTTP clients will make a
  `PerformError`.

* Unbreak everything; thanks Go!

* Send back JSONResponse according to the PerformError

* Update federation invite code too

3 files changed, 11 insertions, 36 deletions

diff --git a/clientapi/routing/createroom.go b/clientapi/routing/createroom.go
index be712482..8682b03a 100644
--- a/clientapi/routing/createroom.go
+++ b/clientapi/routing/createroom.go
@@ -403,15 +403,15 @@ func createRoom(
 			}
 		}
 		// Send the invite event to the roomserver.
-		if err = roomserverAPI.SendInvite(
+		if perr := roomserverAPI.SendInvite(
 			req.Context(), rsAPI,
 			inviteEvent.Headered(roomVersion),
 			strippedState,         // invite room state
 			cfg.Matrix.ServerName, // send as server
 			nil,                   // transaction ID
-		); err != nil {
-			util.GetLogger(req.Context()).WithError(err).Error("SendInvite failed")
-			return jsonerror.InternalServerError()
+		); perr != nil {
+			util.GetLogger(req.Context()).WithError(perr).Error("SendInvite failed")
+			return perr.JSONResponse()
 		}
 	}
 
diff --git a/clientapi/routing/joinroom.go b/clientapi/routing/joinroom.go
index e606e35f..cb68fe19 100644
--- a/clientapi/routing/joinroom.go
+++ b/clientapi/routing/joinroom.go
@@ -15,12 +15,10 @@
 package routing
 
 import (
-	"errors"
 	"net/http"
 
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/dendrite/clientapi/httputil"
-	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/dendrite/userapi/storage/accounts"
@@ -65,32 +63,9 @@ func JoinRoomByIDOrAlias(
 	}
 
 	// Ask the roomserver to perform the join.
-	err = rsAPI.PerformJoin(req.Context(), &joinReq, &joinRes)
-	// Handle known errors first, if this is 0 then there will be no matches (eg on success)
-	switch joinRes.Error {
-	case roomserverAPI.JoinErrorBadRequest:
-		return util.JSONResponse{
-			Code: http.StatusBadRequest,
-			JSON: jsonerror.Unknown(joinRes.ErrMsg),
-		}
-	case roomserverAPI.JoinErrorNoRoom:
-		return util.JSONResponse{
-			Code: http.StatusNotFound,
-			JSON: jsonerror.NotFound(joinRes.ErrMsg),
-		}
-	case roomserverAPI.JoinErrorNotAllowed:
-		return util.JSONResponse{
-			Code: http.StatusForbidden,
-			JSON: jsonerror.Forbidden(joinRes.ErrMsg),
-		}
-	}
-	// this is always populated on generic errors
-	if joinRes.ErrMsg != "" {
-		return util.ErrorResponse(errors.New(joinRes.ErrMsg))
-	}
-	// this is set on network errors in polylith mode
-	if err != nil {
-		return util.ErrorResponse(err)
+	rsAPI.PerformJoin(req.Context(), &joinReq, &joinRes)
+	if joinRes.Error != nil {
+		return joinRes.Error.JSONResponse()
 	}
 
 	return util.JSONResponse{
diff --git a/clientapi/routing/membership.go b/clientapi/routing/membership.go
index 0d4b0d88..aff1730c 100644
--- a/clientapi/routing/membership.go
+++ b/clientapi/routing/membership.go
@@ -111,16 +111,16 @@ func SendMembership(
 	switch membership {
 	case gomatrixserverlib.Invite:
 		// Invites need to be handled specially
-		err = roomserverAPI.SendInvite(
+		perr := roomserverAPI.SendInvite(
 			req.Context(), rsAPI,
 			event.Headered(verRes.RoomVersion),
 			nil, // ask the roomserver to draw up invite room state for us
 			cfg.Matrix.ServerName,
 			nil,
 		)
-		if err != nil {
-			util.GetLogger(req.Context()).WithError(err).Error("producer.SendInvite failed")
-			return jsonerror.InternalServerError()
+		if perr != nil {
+			util.GetLogger(req.Context()).WithError(perr).Error("producer.SendInvite failed")
+			return perr.JSONResponse()
 		}
 	case gomatrixserverlib.Join:
 		// The join membership requires the room id to be sent in the response