Added recaptcha check for POST requests

clientapi/routing/auth_fallback.go

@@ -131,18 +131,8 @@ func AuthFallback(
 	if req.Method == http.MethodGet {
 		// Handle Recaptcha
 		if authType == authtypes.LoginTypeRecaptcha {
-			if cfg.Matrix.RecaptchaEnabled {
-				if cfg.Matrix.RecaptchaPublicKey == "" {
-					return writeErrorMessage(w, req,
-						"This Homeserver doesn't have a recaptcha public key",
-						http.StatusInternalServerError,
-					)
-				}
-			} else {
-				return writeErrorMessage(w, req,
-					"Recaptcha login is disabled on this Homeserver",
-					http.StatusBadRequest,
-				)
+			if err := checkRecaptchaEnabled(&cfg, w, req); err != nil {
+				return err
 			}
 
 			serveRecaptcha()
@@ -153,6 +143,12 @@ func AuthFallback(
 			JSON: jsonerror.NotFound("Unknown auth stage type"),
 		}
 	} else if req.Method == http.MethodPost {
+		// Handle Recaptcha
+		if authType == authtypes.LoginTypeRecaptcha {
+			if err := checkRecaptchaEnabled(&cfg, w, req); err != nil {
+				return err
+			}
+
 			clientIP := req.RemoteAddr
 			err := req.ParseForm()
 			if err != nil {
@@ -172,13 +168,41 @@ func AuthFallback(
 			serveSuccess()
 			return nil
 		}
+
+		return &util.JSONResponse{
+			Code: http.StatusNotFound,
+			JSON: jsonerror.NotFound("Unknown auth stage type"),
+		}
+	}
 	return &util.JSONResponse{
 		Code: http.StatusMethodNotAllowed,
 		JSON: jsonerror.NotFound("Bad method"),
 	}
 }
 
-// WriteErrorMessage writes an error response with the given header and message
+// checkRecaptchaEnabled creates an error response if recaptcha is not usable on homeserver.
+func checkRecaptchaEnabled(
+	cfg *config.Dendrite,
+	w http.ResponseWriter,
+	req *http.Request,
+) *util.JSONResponse {
+	if cfg.Matrix.RecaptchaEnabled {
+		if cfg.Matrix.RecaptchaPublicKey == "" {
+			return writeErrorMessage(w, req,
+				"This Homeserver doesn't have a recaptcha public key",
+				http.StatusInternalServerError,
+			)
+		}
+	} else {
+		return writeErrorMessage(w, req,
+			"Recaptcha login is disabled on this Homeserver",
+			http.StatusBadRequest,
+		)
+	}
+	return nil
+}
+
+// writeErrorMessage writes an error response with the given header and message
 func writeErrorMessage(
 	w http.ResponseWriter, req *http.Request,
 	message string, header int,