Generic-based internal HTTP API (#2626)

* Generic-based internal HTTP API (tested out on a few endpoints in the federation API)

* Add `PerformInvite`

* More tweaks

* Fix metric name

* Fix LookupStateIDs

* Lots of changes to clients

* Some serverside stuff

* Some error handling

* Use paths as metric names

* Revert "Use paths as metric names"

This reverts commit a9323a6a343f5ce6461a2e5bd570fe06465f1b15.

* Namespace metric names

* Remove duplicate entry

* Remove another duplicate entry

* Tweak error handling

* Some more tweaks

* Update error behaviour

* Some more error tweaking

* Fix API path for `PerformDeleteKeys`

* Fix another path

* Tweak federation client proxying

* Fix another path

* Don't return typed nils

* Some more tweaks, not that it makes any difference

* Tweak federation client proxying

* Maybe fix the key backup test

2 files changed, 11 insertions, 37 deletions

diff --git a/appservice/inthttp/client.go b/appservice/inthttp/client.go
index 0a8baea9..3ae2c927 100644
--- a/appservice/inthttp/client.go
+++ b/appservice/inthttp/client.go
@@ -7,7 +7,6 @@ import (
 
 	"github.com/matrix-org/dendrite/appservice/api"
 	"github.com/matrix-org/dendrite/internal/httputil"
-	"github.com/opentracing/opentracing-go"
 )
 
 // HTTP paths for the internal HTTP APIs
@@ -42,11 +41,10 @@ func (h *httpAppServiceQueryAPI) RoomAliasExists(
 	request *api.RoomAliasExistsRequest,
 	response *api.RoomAliasExistsResponse,
 ) error {
-	span, ctx := opentracing.StartSpanFromContext(ctx, "appserviceRoomAliasExists")
-	defer span.Finish()
-
-	apiURL := h.appserviceURL + AppServiceRoomAliasExistsPath
-	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+	return httputil.CallInternalRPCAPI(
+		"RoomAliasExists", h.appserviceURL+AppServiceRoomAliasExistsPath,
+		h.httpClient, ctx, request, response,
+	)
 }
 
 // UserIDExists implements AppServiceQueryAPI
@@ -55,9 +53,8 @@ func (h *httpAppServiceQueryAPI) UserIDExists(
 	request *api.UserIDExistsRequest,
 	response *api.UserIDExistsResponse,
 ) error {
-	span, ctx := opentracing.StartSpanFromContext(ctx, "appserviceUserIDExists")
-	defer span.Finish()
-
-	apiURL := h.appserviceURL + AppServiceUserIDExistsPath
-	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+	return httputil.CallInternalRPCAPI(
+		"UserIDExists", h.appserviceURL+AppServiceUserIDExistsPath,
+		h.httpClient, ctx, request, response,
+	)
 }
diff --git a/appservice/inthttp/server.go b/appservice/inthttp/server.go
index 645b4387..01d9f989 100644
--- a/appservice/inthttp/server.go
+++ b/appservice/inthttp/server.go
@@ -1,43 +1,20 @@
 package inthttp
 
 import (
-	"encoding/json"
-	"net/http"
-
 	"github.com/gorilla/mux"
 	"github.com/matrix-org/dendrite/appservice/api"
 	"github.com/matrix-org/dendrite/internal/httputil"
-	"github.com/matrix-org/util"
 )
 
 // AddRoutes adds the AppServiceQueryAPI handlers to the http.ServeMux.
 func AddRoutes(a api.AppServiceInternalAPI, internalAPIMux *mux.Router) {
 	internalAPIMux.Handle(
 		AppServiceRoomAliasExistsPath,
-		httputil.MakeInternalAPI("appserviceRoomAliasExists", func(req *http.Request) util.JSONResponse {
-			var request api.RoomAliasExistsRequest
-			var response api.RoomAliasExistsResponse
-			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
-				return util.ErrorResponse(err)
-			}
-			if err := a.RoomAliasExists(req.Context(), &request, &response); err != nil {
-				return util.ErrorResponse(err)
-			}
-			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
-		}),
+		httputil.MakeInternalRPCAPI("AppserviceRoomAliasExists", a.RoomAliasExists),
 	)
+
 	internalAPIMux.Handle(
 		AppServiceUserIDExistsPath,
-		httputil.MakeInternalAPI("appserviceUserIDExists", func(req *http.Request) util.JSONResponse {
-			var request api.UserIDExistsRequest
-			var response api.UserIDExistsResponse
-			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
-				return util.ErrorResponse(err)
-			}
-			if err := a.UserIDExists(req.Context(), &request, &response); err != nil {
-				return util.ErrorResponse(err)
-			}
-			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
-		}),
+		httputil.MakeInternalRPCAPI("AppserviceUserIDExists", a.UserIDExists),
 	)
 }