fix: harden Web image admission

packages/attachment/attachment-local/tests/image.spec.ts

@@ -1,93 +1,42 @@
+import sharp from 'sharp'
 import { describe, expect, it } from 'vitest'
 import { detectImage } from '../src/image.ts'
 
-function bytes(text: string): number[] {
-  return [...Buffer.from(text, 'ascii')]
+async function raster(format: 'png' | 'jpeg' | 'webp' | 'gif'): Promise<Uint8Array> {
+  const image = sharp({
+    create: { width: 3, height: 2, channels: 4, background: { r: 1, g: 2, b: 3, alpha: 1 } },
+  })
+  return new Uint8Array(await image.toFormat(format).toBuffer())
 }
 
-function webp(chunk: string, mutate: (data: Uint8Array) => void): Uint8Array {
-  const data = new Uint8Array(30)
-  data.set(bytes('RIFF'), 0)
-  data.set([22, 0, 0, 0], 4)
-  data.set(bytes('WEBP'), 8)
-  data.set(bytes(chunk), 12)
-  mutate(data)
-  return data
-}
-
-describe('raster header detection', () => {
-  it('detects PNG dimensions', () => {
-    const data = Uint8Array.from(Buffer.from(
-      'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNk+A8AAQUBAScY42YAAAAASUVORK5CYII=',
-      'base64',
-    ))
-    expect(detectImage(data)).toEqual({ mediaType: 'image/png', width: 1, height: 1 })
+describe('raster decoding', () => {
+  it('decodes every supported format and its intrinsic dimensions', async () => {
+    for (const [format, mediaType] of [
+      ['png', 'image/png'],
+      ['jpeg', 'image/jpeg'],
+      ['webp', 'image/webp'],
+      ['gif', 'image/gif'],
+    ] as const) {
+      await expect(detectImage(await raster(format)))
+        .resolves.toEqual({ mediaType, width: 3, height: 2 })
+    }
   })
 
-  it('detects both GIF revisions and rejects zero dimensions', () => {
-    expect(detectImage(Uint8Array.from([...bytes('GIF87a'), 3, 0, 2, 0])))
-      .toEqual({ mediaType: 'image/gif', width: 3, height: 2 })
-    expect(detectImage(Uint8Array.from([...bytes('GIF89a'), 4, 0, 5, 0])))
-      .toEqual({ mediaType: 'image/gif', width: 4, height: 5 })
-    expect(() => detectImage(Uint8Array.from([...bytes('GIF89a'), 0, 0, 1, 0])))
-      .toThrow(/positive/)
-    expect(() => detectImage(Uint8Array.from([...bytes('GIF89a'), 1, 0, 0, 0])))
-      .toThrow(/positive/)
+  it('rejects excess decoded pixels before decoding', async () => {
+    await expect(detectImage(await raster('png'), 5))
+      .rejects.toMatchObject({ code: 'IMAGE_TOO_MANY_PIXELS' })
   })
 
-  it('walks JPEG marker forms and reports malformed dimensions', () => {
-    const sof = [0xff, 0xc0, 0, 7, 8, 0, 2, 0, 3]
-    expect(detectImage(Uint8Array.from([0xff, 0xd8, ...sof])))
-      .toEqual({ mediaType: 'image/jpeg', width: 3, height: 2 })
-    expect(detectImage(Uint8Array.from([
-      0xff, 0xd8,
-      0xe0, 0, 2,
-      0x01,
-      0xff, ...sof,
-    ]))).toEqual({ mediaType: 'image/jpeg', width: 3, height: 2 })
-
-    expect(() => detectImage(Uint8Array.from([0xff, 0xd8, 0xd9, 0, 0, 0])))
-      .toThrow(/missing/)
-    expect(() => detectImage(Uint8Array.from([0xff, 0xd8, 0xff, 0xff, 0xff, 0xff])))
-      .toThrow(/missing/)
-    expect(() => detectImage(Uint8Array.from([0xff, 0xd8, 0xe0, 0, 1, 0])))
-      .toThrow(/truncated/)
-    expect(() => detectImage(Uint8Array.from([0xff, 0xd8, 0xe0, 0, 9, 0])))
-      .toThrow(/truncated/)
-    expect(() => detectImage(Uint8Array.from([0xff, 0xd8, 0xc0, 0, 6, 0, 0, 0, 0])))
-      .toThrow(/dimensions are truncated/)
-  })
-
-  it('detects each WebP header and rejects truncated or unknown chunks', () => {
-    expect(detectImage(webp('VP8X', (data) => {
-      data.set([2, 0, 0], 24)
-      data.set([3, 0, 0], 27)
-    }))).toEqual({ mediaType: 'image/webp', width: 3, height: 4 })
-
-    expect(detectImage(webp('VP8L', (data) => {
-      data[20] = 0x2f
-      data.set([2, 0, 1, 0], 21)
-    }))).toEqual({ mediaType: 'image/webp', width: 3, height: 5 })
-
-    expect(detectImage(webp('VP8 ', (data) => {
-      data.set([0x9d, 0x01, 0x2a], 23)
-      data.set([6, 0, 7, 0], 26)
-    }))).toEqual({ mediaType: 'image/webp', width: 6, height: 7 })
-
-    const truncated = webp('VP8X', () => {})
-    truncated[4] = 23
-    expect(() => detectImage(truncated)).toThrow(/truncated/)
-    expect(() => detectImage(webp('NOPE', () => {}))).toThrow(/dimensions are missing/)
-    expect(() => detectImage(webp('VP8L', () => {}))).toThrow(/dimensions are missing/)
-    expect(() => detectImage(webp('VP8 ', () => {}))).toThrow(/dimensions are missing/)
-  })
-
-  it('rejects unrecognized bytes and near-miss signatures', () => {
-    expect(() => detectImage(new Uint8Array(0))).toThrow(/Unsupported/)
-    expect(() => detectImage(Uint8Array.from([...bytes('GIFxxa'), 1, 0, 1, 0])))
-      .toThrow(/Unsupported/)
-    const nearWebp = webp('VP8X', () => {})
-    nearWebp[8] = 0
-    expect(() => detectImage(nearWebp)).toThrow(/Unsupported/)
+  it('rejects malformed bytes and truncated payloads with readable headers', async () => {
+    await expect(detectImage(Uint8Array.of(1, 2, 3)))
+      .rejects.toMatchObject({ code: 'INVALID_IMAGE' })
+    const unsupported = await sharp({
+      create: { width: 1, height: 1, channels: 4, background: { r: 0, g: 0, b: 0, alpha: 1 } },
+    }).tiff().toBuffer()
+    await expect(detectImage(unsupported)).rejects.toMatchObject({ code: 'INVALID_IMAGE' })
+    const complete = await raster('png')
+    const truncated = complete.subarray(0, 62)
+    await expect(sharp(truncated).metadata()).resolves.toMatchObject({ width: 3, height: 2 })
+    await expect(detectImage(truncated)).rejects.toMatchObject({ code: 'INVALID_IMAGE' })
   })
 })