Add trailing slash redirection middleware.

src/index.js

@@ -185,7 +185,8 @@ let middleware = [
   require("./middleware/rewriteURL.js"),
   require("./middleware/responseHeaders.js"),
   require("./middleware/checkForbiddenPaths.js"),
-  require("./middleware/nonStandardCodesAndHttpAuthentication.js")
+  require("./middleware/nonStandardCodesAndHttpAuthentication.js"),
+  require("./middleware/redirectTrailingSlashes.js")
 ];
 
 function addMiddleware(mw) {

src/middleware/redirectTrailingSlashes.js

@@ -0,0 +1,42 @@
+const fs = require("fs");
+const url = require("url");
+
+module.exports = (req, res, logFacilities, config, next) => {
+  // Trailing slash redirection
+    if (
+      !req.isProxy &&
+      !config.disableTrailingSlashRedirects &&
+      req.parsedURL.pathname[req.parsedURL.pathname.length - 1] != "/" &&
+      req.originalParsedURL.pathname[
+        req.originalParsedURL.pathname.length - 1
+      ] != "/"
+    ) {
+      fs.stat(
+        "." + decodeURIComponent(req.parsedURL.pathname),
+        function (err, stats) {
+          if (err || !stats.isDirectory()) {
+            try {
+              next();
+            } catch (err) {
+              res.error(500, err);
+            }
+          } else {
+            var destinationURL = new url.Url();
+            destinationURL.path = null;
+            destinationURL.href = null;
+            destinationURL.pathname = req.originalParsedURL.pathname + "/";
+            destinationURL.hostname = null;
+            destinationURL.host = null;
+            destinationURL.port = null;
+            destinationURL.protocol = null;
+            destinationURL.slashes = null;
+            destinationURL = url.format(destinationURL);
+            res.redirect(destinationURL);
+          }
+        },
+      );
+    } else {
+      next();
+    }
+
+};

src/middleware/rewriteURL.js

@@ -12,6 +12,8 @@ module.exports = (req, res, logFacilities, config, next) => {
     res.error(400);
   }
 
+  req.originalParsedURL = req.parsedURL;
+
   // Handle URL rewriting
   const rewriteURL = (address, map, callback, _fileState, _mapBegIndex) => {
     let rewrittenURL = address;