From 79eae6faf5d78bf6d26a66c2c2e9caa6fe08e863 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Fri, 17 Dec 2021 10:21:58 +0100
Subject: [PATCH 1/2] perf: use a random pool

---
 lib/random-util.js | 39 +++++++++++++++++++++++++++++++++++++++
 lib/sender.js      |  4 ++--
 2 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 lib/random-util.js

diff --git a/lib/random-util.js b/lib/random-util.js
new file mode 100644
index 000000000..1039217b2
--- /dev/null
+++ b/lib/random-util.js
@@ -0,0 +1,39 @@
+'use strict';
+
+const RANDOM_POOL_SIZE = 8192;
+const RANDOM_POOL_REFRESH = 1024;
+
+let randomPool = Buffer.alloc(RANDOM_POOL_SIZE);
+let randomPoolIdx = RANDOM_POOL_SIZE;
+
+function onRandomBytes (err, buf) {
+  randomPending = false;
+  if (!err) {
+    randomPool = buf;
+    randomPoolIdx = 0;
+  }
+}
+
+let randomPending = true;
+crypto.randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
+
+function randomFillMask (buffer) {
+  if (RANDOM_POOL_SIZE - randomPoolIdx < 4) {
+    // assert(randomPending)
+    return crypto.randomFillSync(buffer, offset, size);
+  }
+
+  buffer[0] = randomPool[randomPoolIdx++];
+  buffer[1] = randomPool[randomPoolIdx++];
+  buffer[2] = randomPool[randomPoolIdx++];
+  buffer[3] = randomPool[randomPoolIdx++];
+
+  if (RANDOM_POOL_SIZE - randomPoolIdx < RANDOM_POOL_REFRESH && !randomPending) {
+    randomPending = true;
+    crypto.randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
+  }
+
+  return buffer;
+}
+
+module.exports = { randomFillMask };
diff --git a/lib/sender.js b/lib/sender.js
index 4490a623b..082237b91 100644
--- a/lib/sender.js
+++ b/lib/sender.js
@@ -4,7 +4,7 @@
 
 const net = require('net');
 const tls = require('tls');
-const { randomFillSync } = require('crypto');
+const { randomFillMask } = require('./random-util');
 
 const PerMessageDeflate = require('./permessage-deflate');
 const { EMPTY_BUFFER } = require('./constants');
@@ -81,7 +81,7 @@ class Sender {
 
     if (!options.mask) return [target, data];
 
-    randomFillSync(mask, 0, 4);
+    randomFillMask(mask);
 
     target[1] |= 0x80;
     target[offset - 4] = mask[0];

From 238a7230e89662e269409c5feb7d1c2f644b6640 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Fri, 17 Dec 2021 11:25:21 +0100
Subject: [PATCH 2/2] fixup

---
 lib/random-util.js | 39 ---------------------------------------
 lib/sender.js      | 39 +++++++++++++++++++++++++++++++++------
 2 files changed, 33 insertions(+), 45 deletions(-)
 delete mode 100644 lib/random-util.js

diff --git a/lib/random-util.js b/lib/random-util.js
deleted file mode 100644
index 1039217b2..000000000
--- a/lib/random-util.js
+++ /dev/null
@@ -1,39 +0,0 @@
-'use strict';
-
-const RANDOM_POOL_SIZE = 8192;
-const RANDOM_POOL_REFRESH = 1024;
-
-let randomPool = Buffer.alloc(RANDOM_POOL_SIZE);
-let randomPoolIdx = RANDOM_POOL_SIZE;
-
-function onRandomBytes (err, buf) {
-  randomPending = false;
-  if (!err) {
-    randomPool = buf;
-    randomPoolIdx = 0;
-  }
-}
-
-let randomPending = true;
-crypto.randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
-
-function randomFillMask (buffer) {
-  if (RANDOM_POOL_SIZE - randomPoolIdx < 4) {
-    // assert(randomPending)
-    return crypto.randomFillSync(buffer, offset, size);
-  }
-
-  buffer[0] = randomPool[randomPoolIdx++];
-  buffer[1] = randomPool[randomPoolIdx++];
-  buffer[2] = randomPool[randomPoolIdx++];
-  buffer[3] = randomPool[randomPoolIdx++];
-
-  if (RANDOM_POOL_SIZE - randomPoolIdx < RANDOM_POOL_REFRESH && !randomPending) {
-    randomPending = true;
-    crypto.randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
-  }
-
-  return buffer;
-}
-
-module.exports = { randomFillMask };
diff --git a/lib/sender.js b/lib/sender.js
index 082237b91..25df14cde 100644
--- a/lib/sender.js
+++ b/lib/sender.js
@@ -4,7 +4,7 @@
 
 const net = require('net');
 const tls = require('tls');
-const { randomFillMask } = require('./random-util');
+const { randomBytes } = require('crypto');
 
 const PerMessageDeflate = require('./permessage-deflate');
 const { EMPTY_BUFFER } = require('./constants');
@@ -13,6 +13,22 @@ const { mask: applyMask, toBuffer } = require('./buffer-util');
 
 const mask = Buffer.alloc(4);
 
+const RANDOM_POOL_SIZE = 8192;
+const RANDOM_POOL_REFRESH = 1024;
+
+let randomPool = Buffer.alloc(0);
+let randomPoolIdx = 0;
+let randomPending = true;
+
+function onRandomBytes(err, buf) {
+  randomPending = false;
+  if (!err) {
+    randomPool = buf;
+    randomPoolIdx = 0;
+  }
+}
+randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
+
 /**
  * HyBi Sender implementation.
  */
@@ -81,13 +97,24 @@ class Sender {
 
     if (!options.mask) return [target, data];
 
-    randomFillMask(mask);
+    if (randomPool.length - randomPoolIdx < 4) {
+      randomPool = randomBytes(32);
+      randomPoolIdx = 0;
+    }
 
     target[1] |= 0x80;
-    target[offset - 4] = mask[0];
-    target[offset - 3] = mask[1];
-    target[offset - 2] = mask[2];
-    target[offset - 1] = mask[3];
+    target[offset - 4] = mask[0] = randomPool[randomPoolIdx++];
+    target[offset - 3] = mask[1] = randomPool[randomPoolIdx++];
+    target[offset - 2] = mask[2] = randomPool[randomPoolIdx++];
+    target[offset - 1] = mask[3] = randomPool[randomPoolIdx++];
+
+    if (
+      !randomPending &&
+      randomPool.length - randomPoolIdx < RANDOM_POOL_REFRESH
+    ) {
+      randomPending = true;
+      randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
+    }
 
     if (merge) {
       applyMask(data, mask, target, offset, data.length);