fix challengeCallbacks

src/certnode/lib/client.js

@@ -40,7 +40,7 @@ class Client {
     /** @type {import('crypto').KeyObject} */
     this.accountPublicKey = null
     this.directoryUrl = directoryUrl
-    this.challengeCallbacks = {}
+    this.challengeCallbacks = null
     this.hasDirectory = false
     this.myAccountUrl = ''
     this.newAccountUrl = ''
@@ -438,13 +438,14 @@ class Client {
         reject(new Error('Timed out waiting for server request'))
       }, 10e3);
       let hasResolved = false;
-      this.challengeCallbacks[domain] = function () {
+      this.challengeCallbacks = () => {
         if (!hasResolved)
           setTimeout(resolve, 100);
         else
           return challenge.token + '.' + this.thumbprint;
         hasResolved = true;
         clearTimeout(time);
+        this.challengeCallbacks = null;
         return challenge.token + '.' + this.thumbprint;
       }
     });

src/client.js

@@ -35,12 +35,12 @@ const acme_prefix = '/.well-known/acme-challenge/';
 const listener = async function (/** @type {import('http').IncomingMessage} */ req, /** @type {import('http').ServerResponse} */ res) {
     try {
         if (req.url.startsWith(acme_prefix)) {
-            if (client.challengeCallbacks[req.headers.host]) {
+            if (client.challengeCallbacks) {
                 res.writeHead(200, {
                     // This is important :)
                     'content-type': 'application/octet-stream'
                 });
-                res.write(client.challengeCallbacks[req.headers.host]());
+                res.write(client.challengeCallbacks());
             } else {
                 res.writeHead(404)
             }