From 2c47959600fd3df21f122023c7757e3048af8999 Mon Sep 17 00:00:00 2001
From: Roman Isaev <mdnight@riseup.net>
Date: Sun, 22 Dec 2024 00:23:25 +0000
Subject: [PATCH] mas: added username_available endpoint

---
 clientapi/routing/admin.go   | 21 +++++++++++++++++++++
 clientapi/routing/routing.go |  7 ++++++-
 internal/httputil/httpapi.go | 32 ++++++++++++++++++++++++++++++++
 setup/mscs/mscs.go           |  2 +-
 4 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/clientapi/routing/admin.go b/clientapi/routing/admin.go
index 48e58209..40881166 100644
--- a/clientapi/routing/admin.go
+++ b/clientapi/routing/admin.go
@@ -496,6 +496,27 @@ func AdminDownloadState(req *http.Request, device *api.Device, rsAPI roomserverA
 	}
 }
 
+func AdminCheckUsernameAvailable(
+	req *http.Request,
+	userAPI userapi.ClientUserAPI,
+	cfg *config.ClientAPI,
+) util.JSONResponse {
+	username := req.URL.Query().Get("username")
+	if username == "" {
+		return util.MessageResponse(http.StatusBadRequest, "Query parameter 'username' is missing or empty")
+	}
+	rq := userapi.QueryAccountAvailabilityRequest{Localpart: username, ServerName: cfg.Matrix.ServerName}
+	rs := userapi.QueryAccountAvailabilityResponse{}
+	if err := userAPI.QueryAccountAvailability(req.Context(), &rq, &rs); err != nil {
+		return util.ErrorResponse(err)
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: map[string]bool{"available": rs.Available},
+	}
+}
+
 // GetEventReports returns reported events for a given user/room.
 func GetEventReports(
 	req *http.Request,
diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index 373fa03f..0544c3c2 100644
--- a/clientapi/routing/routing.go
+++ b/clientapi/routing/routing.go
@@ -334,7 +334,12 @@ func Setup(
 				return util.JSONResponse{Code: http.StatusOK, JSON: map[string]string{
 					"issuer": m.Issuer,
 				}}
-			}))
+			})).Methods(http.MethodGet)
+
+		synapseAdminRouter.Handle("/admin/v1/username_available",
+			httputil.MakeServiceAdminAPI("admin_username_available", m.AdminToken, func(r *http.Request) util.JSONResponse {
+				return AdminCheckUsernameAvailable(r, userAPI, cfg)
+			})).Methods(http.MethodGet)
 	}
 
 	if mscCfg.Enabled("msc2753") {
diff --git a/internal/httputil/httpapi.go b/internal/httputil/httpapi.go
index d3255767..5a332d6f 100644
--- a/internal/httputil/httpapi.go
+++ b/internal/httputil/httpapi.go
@@ -136,6 +136,38 @@ func MakeAdminAPI(
 	})
 }
 
+// MakeServiceAdminAPI is a wrapper around MakeAuthAPI which enforces that the request can only be
+// completed by a trusted service e.g. Matrix Auth Service.
+func MakeServiceAdminAPI(
+	metricsName, serviceToken string,
+	f func(*http.Request) util.JSONResponse,
+) http.Handler {
+	h := func(req *http.Request) util.JSONResponse {
+		logger := util.GetLogger(req.Context())
+		token, err := auth.ExtractAccessToken(req)
+
+		if err != nil {
+			logger.Debugf("ExtractAccessToken %s -> HTTP %d", req.RemoteAddr, http.StatusUnauthorized)
+			return util.JSONResponse{
+				Code: http.StatusUnauthorized,
+				JSON: spec.MissingToken(err.Error()),
+			}
+		}
+		if token != serviceToken {
+			logger.Debugf("Invalid service token '%s'", token)
+			return util.JSONResponse{
+				Code: http.StatusForbidden,
+				JSON: spec.UnknownToken(token),
+			}
+		}
+		// add the service addr to the logger
+		logger = logger.WithField("service_useragent", req.UserAgent())
+		req = req.WithContext(util.ContextWithLogger(req.Context(), logger))
+		return f(req)
+	}
+	return MakeExternalAPI(metricsName, h)
+}
+
 // MakeExternalAPI turns a util.JSONRequestHandler function into an http.Handler.
 // This is used for APIs that are called from the internet.
 func MakeExternalAPI(metricsName string, f func(*http.Request) util.JSONResponse) http.Handler {
diff --git a/setup/mscs/mscs.go b/setup/mscs/mscs.go
index 91bc1a82..6a220e62 100644
--- a/setup/mscs/mscs.go
+++ b/setup/mscs/mscs.go
@@ -37,7 +37,7 @@ func EnableMSC(cfg *config.Dendrite, cm *sqlutil.Connections, routers httputil.R
 		return msc2836.Enable(cfg, cm, routers, monolith.RoomserverAPI, monolith.FederationAPI, monolith.UserAPI, monolith.KeyRing)
 	case "msc2444": // enabled inside federationapi
 	case "msc2753": // enabled inside clientapi
-	case "msc2965":	// enabled inside clientapi
+	case "msc2965": // enabled inside clientapi
 	default:
 		logrus.Warnf("EnableMSC: unknown MSC '%s', this MSC is either not supported or is natively supported by Dendrite", msc)
 	}