From 76cb9c2a39d477a64824a985ade40507e3bbade1 Mon Sep 17 00:00:00 2001
From: Adam Mathes <adam@adammathes.com>
Date: Fri, 13 Feb 2026 21:34:48 -0800
Subject: feat(vanilla): add testing infrastructure and tests (NK-wjnczv)

---
 .../undici/lib/web/websocket/permessage-deflate.js | 70 ++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 vanilla/node_modules/undici/lib/web/websocket/permessage-deflate.js

(limited to 'vanilla/node_modules/undici/lib/web/websocket/permessage-deflate.js')

diff --git a/vanilla/node_modules/undici/lib/web/websocket/permessage-deflate.js b/vanilla/node_modules/undici/lib/web/websocket/permessage-deflate.js
new file mode 100644
index 0000000..76cb366
--- /dev/null
+++ b/vanilla/node_modules/undici/lib/web/websocket/permessage-deflate.js
@@ -0,0 +1,70 @@
+'use strict'
+
+const { createInflateRaw, Z_DEFAULT_WINDOWBITS } = require('node:zlib')
+const { isValidClientWindowBits } = require('./util')
+
+const tail = Buffer.from([0x00, 0x00, 0xff, 0xff])
+const kBuffer = Symbol('kBuffer')
+const kLength = Symbol('kLength')
+
+class PerMessageDeflate {
+  /** @type {import('node:zlib').InflateRaw} */
+  #inflate
+
+  #options = {}
+
+  constructor (extensions) {
+    this.#options.serverNoContextTakeover = extensions.has('server_no_context_takeover')
+    this.#options.serverMaxWindowBits = extensions.get('server_max_window_bits')
+  }
+
+  decompress (chunk, fin, callback) {
+    // An endpoint uses the following algorithm to decompress a message.
+    // 1.  Append 4 octets of 0x00 0x00 0xff 0xff to the tail end of the
+    //     payload of the message.
+    // 2.  Decompress the resulting data using DEFLATE.
+
+    if (!this.#inflate) {
+      let windowBits = Z_DEFAULT_WINDOWBITS
+
+      if (this.#options.serverMaxWindowBits) { // empty values default to Z_DEFAULT_WINDOWBITS
+        if (!isValidClientWindowBits(this.#options.serverMaxWindowBits)) {
+          callback(new Error('Invalid server_max_window_bits'))
+          return
+        }
+
+        windowBits = Number.parseInt(this.#options.serverMaxWindowBits)
+      }
+
+      this.#inflate = createInflateRaw({ windowBits })
+      this.#inflate[kBuffer] = []
+      this.#inflate[kLength] = 0
+
+      this.#inflate.on('data', (data) => {
+        this.#inflate[kBuffer].push(data)
+        this.#inflate[kLength] += data.length
+      })
+
+      this.#inflate.on('error', (err) => {
+        this.#inflate = null
+        callback(err)
+      })
+    }
+
+    this.#inflate.write(chunk)
+    if (fin) {
+      this.#inflate.write(tail)
+    }
+
+    this.#inflate.flush(() => {
+      const full = Buffer.concat(this.#inflate[kBuffer], this.#inflate[kLength])
+
+      this.#inflate[kBuffer].length = 0
+      this.#inflate[kLength] = 0
+
+      callback(null, full)
+    })
+  }
+}
+
+module.exports = { PerMessageDeflate }
-- 
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