From e64da0f32c9619ca6d995577e31db16dc7cee6ef Mon Sep 17 00:00:00 2001
From: Alex Kern <alex@kern.io>
Date: Sun, 30 Mar 2025 21:14:45 -0700
Subject: [PATCH] Improves random generation (#251)

---
 src/channel.ts |  2 +-
 src/slugs.ts   | 32 +++++++++++++++++---------------
 2 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/src/channel.ts b/src/channel.ts
index c22c352..d2fc79d 100644
--- a/src/channel.ts
+++ b/src/channel.ts
@@ -38,7 +38,7 @@ async function generateShortSlugUntilUnique(
   checkExists: (key: string) => Promise<boolean>,
 ): Promise<string> {
   for (let i = 0; i < config.shortSlug.maxAttempts; i++) {
-    const slug = generateShortSlug()
+    const slug = await generateShortSlug()
     const exists = await checkExists(getShortSlugKey(slug))
     if (!exists) {
       return slug
diff --git a/src/slugs.ts b/src/slugs.ts
index 5e4aa00..1ce6e35 100644
--- a/src/slugs.ts
+++ b/src/slugs.ts
@@ -25,12 +25,17 @@ function generateRandomWords(
     }
 
     const getRandomInt = (max: number): number => {
-      const buffer = new Uint32Array(1)
-      if (typeof window !== 'undefined' && window.crypto) {
-        window.crypto.getRandomValues(buffer)
-      } else {
-        crypto.randomFillSync(buffer)
-      }
+      const limit = 4294967295 - (4294967295 % max) // uint32 max
+
+      let buffer = new Uint32Array(1)
+      do {
+        if (typeof window !== 'undefined' && window.crypto) {
+          window.crypto.getRandomValues(buffer)
+        } else {
+          crypto.randomFillSync(buffer)
+        }
+      } while (buffer[0] >= limit)
+
       return buffer[0] % max
     }
 
@@ -44,15 +49,12 @@ function generateRandomWords(
   })
 }
 
-export const generateShortSlug = (): string => {
-  let result = ''
-  for (let i = 0; i < config.shortSlug.numChars; i++) {
-    result +=
-      config.shortSlug.chars[
-        Math.floor(Math.random() * config.shortSlug.chars.length)
-      ]
-  }
-  return result
+export const generateShortSlug = async (): Promise<string> => {
+  const parts = await generateRandomWords(
+    config.shortSlug.chars.split(''),
+    config.shortSlug.numChars,
+  )
+  return parts.join('')
 }
 
 export const generateLongSlug = async (): Promise<string> => {