From 54ea665b52b6425280cbaf9c2b62903ff72f7c03 Mon Sep 17 00:00:00 2001
From: K <kay-is@users.noreply.github.com>
Date: Tue, 26 Sep 2023 08:35:38 +0000
Subject: [PATCH] refactor(sandbox, arns): switch params to config

As both middlewares need the root host's subdomain count,
moving it to the config eliminates duplicates.

This also allows to remove the rootHost constructor param and take it
directly from the config.
---
 src/app.ts                |  2 --
 src/config.ts             |  2 ++
 src/middleware/arns.ts    |  8 +++-----
 src/middleware/sandbox.ts | 14 ++++++--------
 4 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/app.ts b/src/app.ts
index 32589ac7..6df5b94a 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -83,14 +83,12 @@ if (config.ARNS_ROOT_HOST !== undefined) {
   app.use(
     createArnsMiddleware({
       dataHandler,
-      rootHost: config.ARNS_ROOT_HOST,
       nameResolver: system.nameResolver,
     }),
   );
 
   app.use(
     createSandboxMiddleware({
-      rootHost: config.ARNS_ROOT_HOST,
       sandboxProtocol: config.SANDBOX_PROTOCOL,
     }),
   );
diff --git a/src/config.ts b/src/config.ts
index 6c3fed52..bf27aab2 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -70,6 +70,8 @@ export const ANS104_INDEX_FILTER = createFilter(
   JSON.parse(ANS104_INDEX_FILTER_STRING),
 );
 export const ARNS_ROOT_HOST = env.varOrUndefined('ARNS_ROOT_HOST');
+export const ROOT_HOST_SUBDOMAIN_LENGTH =
+  ARNS_ROOT_HOST !== undefined ? ARNS_ROOT_HOST.split('.').length - 2 : 0;
 export const SANDBOX_PROTOCOL = env.varOrUndefined('SANDBOX_PROTOCOL');
 export const START_WRITERS =
   env.varOrDefault('START_WRITERS', 'true') === 'true';
diff --git a/src/middleware/arns.ts b/src/middleware/arns.ts
index 2483f61b..d537bba9 100644
--- a/src/middleware/arns.ts
+++ b/src/middleware/arns.ts
@@ -18,6 +18,7 @@
 import { Handler } from 'express';
 import { asyncMiddleware } from 'middleware-async';
 
+import * as config from '../config.js';
 import { sendNotFound } from '../routes/data.js';
 import { NameResolver } from '../types.js';
 
@@ -25,24 +26,21 @@ const EXCLUDED_SUBDOMAINS = new Set('www');
 
 export const createArnsMiddleware = ({
   dataHandler,
-  rootHost,
   nameResolver,
 }: {
   dataHandler: Handler;
-  rootHost: string;
   nameResolver: NameResolver;
 }): Handler =>
   asyncMiddleware(async (req, res, next) => {
-    const rootHostSubdomainLength = rootHost.split('.').length - 2;
     if (
       // Ignore subdomains that are part of the ArNS root hostname.
       !Array.isArray(req.subdomains) ||
-      req.subdomains.length === rootHostSubdomainLength
+      req.subdomains.length === config.ROOT_HOST_SUBDOMAIN_LENGTH
     ) {
       next();
       return;
     }
-    const arnsSubdomain = req.subdomains[req.subdomains.length - 1];
+    const arnsSubdomain = req.subdomains[config.ROOT_HOST_SUBDOMAIN_LENGTH - 1];
     if (
       EXCLUDED_SUBDOMAINS.has(arnsSubdomain) ||
       // Avoid collisions with sandbox URLs by ensuring the subdomain length
diff --git a/src/middleware/sandbox.ts b/src/middleware/sandbox.ts
index ab6604e9..41f0cc53 100644
--- a/src/middleware/sandbox.ts
+++ b/src/middleware/sandbox.ts
@@ -19,11 +19,11 @@ import { Handler, Request } from 'express';
 import url from 'node:url';
 import { base32 } from 'rfc4648';
 
+import * as config from '../config.js';
 import { fromB64Url } from '../lib/encoding.js';
 
-function getRequestSandbox(req: Request, rootHost: string): string | undefined {
-  const rootHostSubdomainLength = rootHost.split('.').length - 2;
-  if (req.subdomains.length > rootHostSubdomainLength) {
+function getRequestSandbox(req: Request): string | undefined {
+  if (req.subdomains.length > config.ROOT_HOST_SUBDOMAIN_LENGTH) {
     return req.subdomains[req.subdomains.length - 1];
   }
   return undefined;
@@ -38,14 +38,12 @@ function sandboxFromId(id: string): string {
 }
 
 export function createSandboxMiddleware({
-  rootHost,
   sandboxProtocol,
 }: {
-  rootHost?: string;
   sandboxProtocol?: string;
 }): Handler {
   return (req, res, next) => {
-    if (rootHost === undefined) {
+    if (config.ARNS_ROOT_HOST === undefined) {
       next();
       return;
     }
@@ -56,7 +54,7 @@ export function createSandboxMiddleware({
       return;
     }
 
-    const reqSandbox = getRequestSandbox(req, rootHost);
+    const reqSandbox = getRequestSandbox(req);
     const idSandbox = sandboxFromId(id);
     if (reqSandbox !== idSandbox) {
       const queryString = url.parse(req.originalUrl).query ?? '';
@@ -64,7 +62,7 @@ export function createSandboxMiddleware({
       const protocol = sandboxProtocol ?? (req.secure ? 'https' : 'http');
       return res.redirect(
         302,
-        `${protocol}://${idSandbox}.${rootHost}${path}?${queryString}`,
+        `${protocol}://${idSandbox}.${config.ARNS_ROOT_HOST}${path}?${queryString}`,
       );
     }