From 0880e3446152ea259650f76a303020ff8080448b Mon Sep 17 00:00:00 2001
From: tt-a1i <53142663+tt-a1i@users.noreply.github.com>
Date: Sun, 21 Jun 2026 13:05:52 +0800
Subject: [PATCH] fix(desktop): reject fractional transfer sizes (#5527)

---
 .../src/handlers/rpc/transfer.test.ts         | 28 +++++++++++++++++++
 .../server-core/src/handlers/rpc/transfer.ts  |  4 +--
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/packages/desktop/packages/server-core/src/handlers/rpc/transfer.test.ts b/packages/desktop/packages/server-core/src/handlers/rpc/transfer.test.ts
index c350f8db0e..29a4d86c34 100644
--- a/packages/desktop/packages/server-core/src/handlers/rpc/transfer.test.ts
+++ b/packages/desktop/packages/server-core/src/handlers/rpc/transfer.test.ts
@@ -65,6 +65,34 @@ afterEach(() => {
 })
 
 describe('chunked transfer handlers', () => {
+  it('rejects fractional chunk counts', async () => {
+    const { start } = createHarness()
+
+    setTransferableHandler('test:echo', async (_ctx, _placeholder, body) => body)
+
+    await expect(start(ctx('client-1'), {
+      totalBytes: 10,
+      chunkCount: 1.5,
+      channel: 'test:echo',
+      args: [null, null],
+      largeArgIndex: 1,
+    })).rejects.toThrow('Invalid chunkCount')
+  })
+
+  it('rejects fractional total byte counts', async () => {
+    const { start } = createHarness()
+
+    setTransferableHandler('test:echo', async (_ctx, _placeholder, body) => body)
+
+    await expect(start(ctx('client-1'), {
+      totalBytes: 10.5,
+      chunkCount: 1,
+      channel: 'test:echo',
+      args: [null, null],
+      largeArgIndex: 1,
+    })).rejects.toThrow('Invalid totalBytes')
+  })
+
   it('rejects chunk uploads from a different client', async () => {
     const { start, chunk } = createHarness()
     const payload = encodeParts({ hello: 'world' })
diff --git a/packages/desktop/packages/server-core/src/handlers/rpc/transfer.ts b/packages/desktop/packages/server-core/src/handlers/rpc/transfer.ts
index e0cd960fa9..a8006a3562 100644
--- a/packages/desktop/packages/server-core/src/handlers/rpc/transfer.ts
+++ b/packages/desktop/packages/server-core/src/handlers/rpc/transfer.ts
@@ -98,10 +98,10 @@ export function registerTransferHandlers(server: RpcServer): void {
     largeArgIndex: number
     checksum?: string
   }) => {
-    if (!opts || typeof opts.chunkCount !== 'number' || opts.chunkCount < 1) {
+    if (!opts || !Number.isInteger(opts.chunkCount) || opts.chunkCount < 1) {
       throw new Error('Invalid chunkCount')
     }
-    if (typeof opts.totalBytes !== 'number' || opts.totalBytes < 0) {
+    if (!Number.isInteger(opts.totalBytes) || opts.totalBytes < 0) {
       throw new Error('Invalid totalBytes')
     }
     if (!opts.channel || typeof opts.channel !== 'string') {