From a5c1faa917645a4e892ae28c2529f918a13078b6 Mon Sep 17 00:00:00 2001
From: "Kamat, Trivikram" <16024985+trivikr@users.noreply.github.com>
Date: Sat, 25 Apr 2026 07:32:04 -0700
Subject: [PATCH 1/2] client: cache llhttp wasm buffer view

Assisted-by: openai:gpt-5.5
Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
---
 lib/dispatcher/client-h1.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/dispatcher/client-h1.js b/lib/dispatcher/client-h1.js
index ea2ec316574..cf8f75a60f4 100644
--- a/lib/dispatcher/client-h1.js
+++ b/lib/dispatcher/client-h1.js
@@ -188,6 +188,7 @@ let currentBufferRef = null
  */
 let currentBufferSize = 0
 let currentBufferPtr = null
+let currentBuffer = null
 
 const USE_NATIVE_TIMER = 0
 const USE_FAST_TIMER = 1
@@ -322,7 +323,11 @@ class Parser {
       currentBufferPtr = llhttp.malloc(currentBufferSize)
     }
 
-    new Uint8Array(llhttp.memory.buffer, currentBufferPtr, currentBufferSize).set(chunk)
+    if (currentBuffer === null || currentBuffer.buffer !== llhttp.memory.buffer) {
+      currentBuffer = new Uint8Array(llhttp.memory.buffer, currentBufferPtr, currentBufferSize)
+    }
+
+    currentBuffer.set(chunk)
 
     // Call `execute` on the wasm parser.
     // We pass the `llhttp_parser` pointer address, the pointer address of buffer view data,

From 27e470c7d643dfbd1f9c0b3ed41f259366b33c9a Mon Sep 17 00:00:00 2001
From: "Kamat, Trivikram" <16024985+trivikr@users.noreply.github.com>
Date: Sat, 25 Apr 2026 07:46:11 -0700
Subject: [PATCH 2/2] fix: refresh wasm parser input view after realloc

---
 lib/dispatcher/client-h1.js |  7 +++-
 test/parser-issues.js       | 66 +++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/lib/dispatcher/client-h1.js b/lib/dispatcher/client-h1.js
index cf8f75a60f4..a0c19abc403 100644
--- a/lib/dispatcher/client-h1.js
+++ b/lib/dispatcher/client-h1.js
@@ -323,7 +323,12 @@ class Parser {
       currentBufferPtr = llhttp.malloc(currentBufferSize)
     }
 
-    if (currentBuffer === null || currentBuffer.buffer !== llhttp.memory.buffer) {
+    if (
+      currentBuffer === null ||
+      currentBuffer.buffer !== llhttp.memory.buffer ||
+      currentBuffer.byteOffset !== currentBufferPtr ||
+      currentBuffer.byteLength !== currentBufferSize
+    ) {
       currentBuffer = new Uint8Array(llhttp.memory.buffer, currentBufferPtr, currentBufferSize)
     }
 
diff --git a/test/parser-issues.js b/test/parser-issues.js
index 859a5f096cb..5c71c5d4167 100644
--- a/test/parser-issues.js
+++ b/test/parser-issues.js
@@ -129,3 +129,69 @@ test('split header value', async (t) => {
 
   await t.completed
 })
+
+test('refreshes wasm input view after reallocating parser buffer', async (t) => {
+  t = tspl(t, { plan: 4 })
+
+  const smallBody = Buffer.from('ok')
+  const largeBody = Buffer.alloc(8192, 'a')
+  const responses = [
+    Buffer.concat([
+      Buffer.from(`HTTP/1.1 200 OK\r\nContent-Length: ${smallBody.length}\r\n\r\n`),
+      smallBody
+    ]),
+    Buffer.concat([
+      Buffer.from(`HTTP/1.1 200 OK\r\nContent-Length: ${largeBody.length}\r\n\r\n`),
+      largeBody
+    ])
+  ]
+
+  const server = net.createServer(socket => {
+    let responsesSent = 0
+
+    socket.on('data', () => {
+      socket.write(responses[responsesSent++])
+    })
+  })
+  after(() => server.close())
+
+  await new Promise(resolve => server.listen(0, resolve))
+
+  const client = new Client(`http://localhost:${server.address().port}`)
+  after(() => client.destroy())
+
+  function request () {
+    return new Promise((resolve, reject) => {
+      client.request({
+        method: 'GET',
+        path: '/'
+      }, (err, { statusCode, body } = {}) => {
+        if (err) {
+          reject(err)
+          return
+        }
+
+        const bufs = []
+
+        body.on('data', buf => {
+          bufs.push(buf)
+        })
+        body.on('end', () => {
+          resolve({
+            statusCode,
+            body: Buffer.concat(bufs)
+          })
+        })
+        body.on('error', reject)
+      })
+    })
+  }
+
+  const smallResponse = await request()
+  t.strictEqual(smallResponse.statusCode, 200)
+  t.strictEqual(smallResponse.body.toString(), smallBody.toString())
+
+  const largeResponse = await request()
+  t.strictEqual(largeResponse.statusCode, 200)
+  t.strictEqual(largeResponse.body.toString(), largeBody.toString())
+})