fix(core,node,fetch,aws-lambda): identify request bodies from one shared header resolution

package.json

@@ -9,7 +9,7 @@
     "prepare": "simple-git-hooks",
     "type:check": "pnpm -r run type:check && tsc",
     "test": "pnpm run -r test && vitest run",
-    "test:coverage": "vitest run --coverage",
+    "test:coverage": "pnpm run -r test && vitest run --coverage",
     "bench": "vitest bench --run",
     "lint": "eslint --max-warnings=0 .",
     "lint:fix": "eslint --max-warnings=0 --fix .",

packages/core/src/utils.test.ts

@@ -1,4 +1,4 @@
-import { flattenStandardHeader, generateContentDisposition, getFilenameFromContentDisposition, mergeStandardHeaders, parseStandardUrl } from './utils'
+import { flattenStandardHeader, generateContentDisposition, getFilenameFromContentDisposition, mergeStandardHeaders, parseStandardUrl, resolveStandardBodyHint } from './utils'
 
 beforeEach(() => {
   vi.clearAllMocks()
@@ -75,6 +75,67 @@ it('getFilenameFromContentDisposition', () => {
   expect(getFilenameFromContentDisposition('attachment; filename*=iso-8859-1\'\'%E9.txt')).toEqual(undefined)
 })
 
+describe('resolveStandardBodyHint', () => {
+  it('standard-server header wins over content headers', () => {
+    expect(resolveStandardBodyHint({ 'standard-server': 'none', 'content-length': '3', 'content-type': 'application/pdf' })).toBe('none')
+    expect(resolveStandardBodyHint({ 'standard-server': 'json', 'content-length': '3', 'content-type': 'application/pdf' })).toBe('json')
+    expect(resolveStandardBodyHint({ 'standard-server': ['file'], 'content-type': 'application/json' })).toBe('file')
+    expect(resolveStandardBodyHint({ 'standard-server': 'octet-stream', 'content-length': '3' })).toBe('octet-stream')
+    expect(resolveStandardBodyHint({ 'standard-server': 'event-stream', 'content-length': '3', 'content-type': 'application/json' })).toBe('event-stream')
+    expect(resolveStandardBodyHint({ 'standard-server': 'form-data', 'content-length': '3', 'content-type': 'application/json' })).toBe('form-data')
+    expect(resolveStandardBodyHint({ 'standard-server': 'url-search-params', 'content-length': '3', 'content-type': 'application/json' })).toBe('url-search-params')
+  })
+
+  it('ignores an unrecognized standard-server header', () => {
+    expect(resolveStandardBodyHint({ 'standard-server': 'invalid', 'content-type': 'application/json' })).toBe('json')
+    expect(resolveStandardBodyHint({ 'standard-server': '', 'content-length': '3' })).toBe('file')
+    // a repeated header flattens to a comma-joined value, which is not a hint
+    expect(resolveStandardBodyHint({ 'standard-server': ['file', 'json'] })).toBe('none')
+  })
+
+  it('falls back to content headers when the standard-server header is unset', () => {
+    expect(resolveStandardBodyHint({ 'standard-server': undefined, 'content-length': '3' })).toBe('file')
+    // an empty array is the unset-header convention
+    expect(resolveStandardBodyHint({ 'standard-server': [], 'content-length': '3' })).toBe('file')
+  })
+
+  it('none when no content-type and no meaningful content-length', () => {
+    expect(resolveStandardBodyHint({})).toBe('none')
+    expect(resolveStandardBodyHint({ 'content-length': '0' })).toBe('none')
+    expect(resolveStandardBodyHint({ 'content-type': [], 'content-length': [] })).toBe('none')
+  })
+
+  it('by content-type', () => {
+    expect(resolveStandardBodyHint({ 'content-type': 'application/json' })).toBe('json')
+    expect(resolveStandardBodyHint({ 'content-type': 'application/json; charset=utf-8' })).toBe('json')
+    expect(resolveStandardBodyHint({ 'content-type': ' application/json ' })).toBe('json')
+    expect(resolveStandardBodyHint({ 'content-type': 'multipart/form-data; boundary=x' })).toBe('form-data')
+    expect(resolveStandardBodyHint({ 'content-type': 'application/x-www-form-urlencoded' })).toBe('url-search-params')
+    expect(resolveStandardBodyHint({ 'content-type': 'text/event-stream' })).toBe('event-stream')
+
+    // content-type wins over content-length
+    expect(resolveStandardBodyHint({ 'content-type': 'application/json', 'content-length': '3' })).toBe('json')
+  })
+
+  it('file when content-length is present', () => {
+    expect(resolveStandardBodyHint({ 'content-length': '3' })).toBe('file')
+    expect(resolveStandardBodyHint({ 'content-length': ['3'] })).toBe('file')
+    expect(resolveStandardBodyHint({ 'content-length': '3', 'content-type': 'application/pdf' })).toBe('file')
+    // an empty file is still a file when a content-type is present
+    expect(resolveStandardBodyHint({ 'content-length': '0', 'content-type': 'application/pdf' })).toBe('file')
+    // an empty content-type is a valid content-type, not an absent one
+    expect(resolveStandardBodyHint({ 'content-length': '0', 'content-type': '' })).toBe('file')
+    expect(resolveStandardBodyHint({ 'content-length': '0', 'content-type': ' ; charset=utf-8' })).toBe('file')
+  })
+
+  it('octet-stream when content-length is absent', () => {
+    expect(resolveStandardBodyHint({ 'content-type': 'application/octet-stream' })).toBe('octet-stream')
+    expect(resolveStandardBodyHint({ 'content-type': 'application/pdf' })).toBe('octet-stream')
+    expect(resolveStandardBodyHint({ 'content-type': 'text/plain', 'content-length': [] })).toBe('octet-stream')
+    expect(resolveStandardBodyHint({ 'content-type': '' })).toBe('octet-stream')
+  })
+})
+
 describe('mergeStandardHeaders', () => {
   afterEach(() => {
     expect(({} as any).polluted).toEqual(undefined)

packages/core/src/utils.ts

@@ -1,4 +1,4 @@
-import type { StandardHeaders, StandardUrl } from './types'
+import type { StandardBodyHint, StandardHeaders, StandardUrl } from './types'
 import { toArray, tryDecodeURIComponent } from '@standardserver/shared'
 
 export function generateContentDisposition(filename: string, type: 'inline' | 'attachment' = 'inline'): string {
@@ -52,6 +52,57 @@ export function flattenStandardHeader(header: string | readonly string[] | undef
   return header.join(', ')
 }
 
+const STANDARD_BODY_HINT_SET: ReadonlySet<string> = new Set<StandardBodyHint>([
+  'json',
+  'form-data',
+  'url-search-params',
+  'event-stream',
+  'octet-stream',
+  'file',
+  'none',
+])
+
+/**
+ * Resolves how a receiver parses a body from the standard headers alone,
+ * mirroring what the body parsers do.
+ */
+export function resolveStandardBodyHint(headers: StandardHeaders): StandardBodyHint {
+  const hint = flattenStandardHeader(headers['standard-server'])
+
+  if (hint !== undefined && STANDARD_BODY_HINT_SET.has(hint)) {
+    return hint as StandardBodyHint
+  }
+
+  const mimeType = flattenStandardHeader(headers['content-type'])?.split(';')[0]?.trim()
+  const contentLength = flattenStandardHeader(headers['content-length'])
+
+  if (mimeType === undefined && (contentLength === undefined || contentLength === '0')) {
+    return 'none'
+  }
+
+  if (mimeType === 'application/json') {
+    return 'json'
+  }
+
+  if (mimeType === 'multipart/form-data') {
+    return 'form-data'
+  }
+
+  if (mimeType === 'application/x-www-form-urlencoded') {
+    return 'url-search-params'
+  }
+
+  if (mimeType === 'text/event-stream') {
+    return 'event-stream'
+  }
+
+  if (contentLength !== undefined) {
+    return 'file'
+  }
+
+  return 'octet-stream'
+}
+
 export function mergeStandardHeaders(a: StandardHeaders, b: StandardHeaders): StandardHeaders {
   const merged = { ...a, ...b }
 

packages/fastify/src/response.test.ts

@@ -150,7 +150,6 @@ describe('sendStandardResponse', () => {
       'content-disposition': 'inline; filename="blob"; filename*=utf-8\'\'blob',
       'content-length': '3',
       'content-type': 'text/plain',
-      'standard-server': 'file',
       'x-custom-header': 'custom-value',
     })
 

packages/fetch/src/body.test.ts

@@ -486,13 +486,46 @@ describe('toFetchBody', () => {
       'content-length': '3',
       'content-type': 'application/pdf',
       'x-custom-header': 'custom-value',
-      'standard-server': 'file',
     })
 
     expect(generateContentDispositionSpy).toHaveBeenCalledTimes(1)
     expect(generateContentDispositionSpy).toHaveBeenCalledWith('blob')
   })
 
+  it('blob with common content-type', () => {
+    const blob = new Blob(['foo'], { type: 'application/json' })
+
+    generateContentDispositionSpy.mockReturnValue('__mocked__')
+
+    const [body, headers] = toFetchBody(blob, baseHeaders, {})
+
+    expect(body).toBe(blob)
+    expect(headers).toEqual({
+      'content-disposition': '__mocked__',
+      'content-length': '3',
+      'content-type': 'application/json',
+      'x-custom-header': 'custom-value',
+      'standard-server': 'file',
+    })
+  })
+
+  it('empty blob without content-type', () => {
+    const blob = new Blob([])
+
+    generateContentDispositionSpy.mockReturnValue('__mocked__')
+
+    const [body, headers] = toFetchBody(blob, baseHeaders, {})
+
+    expect(body).toBe(blob)
+    expect(headers).toEqual({
+      'content-disposition': '__mocked__',
+      'content-length': '0',
+      'content-type': '',
+      'x-custom-header': 'custom-value',
+      'standard-server': 'file',
+    })
+  })
+
   it('file', () => {
     const blob = new File(['foo'], 'foo.pdf', { type: 'application/pdf' })
 
@@ -506,7 +539,6 @@ describe('toFetchBody', () => {
       'content-length': '3',
       'content-type': 'application/pdf',
       'x-custom-header': 'custom-value',
-      'standard-server': 'file',
     })
 
     expect(generateContentDispositionSpy).toHaveBeenCalledTimes(1)
@@ -524,7 +556,6 @@ describe('toFetchBody', () => {
       'content-length': '3',
       'content-type': 'application/pdf',
       'x-custom-header': 'custom-value',
-      'standard-server': 'file',
     })
 
     expect(generateContentDispositionSpy).toHaveBeenCalledTimes(0)

packages/fetch/src/body.ts

@@ -1,6 +1,6 @@
 import type { StandardBody, StandardBodyHint, StandardHeaders } from '@standardserver/core'
 import type { ToEventStreamOptions } from './event-stream'
-import { generateContentDisposition, getFilenameFromContentDisposition } from '@standardserver/core'
+import { generateContentDisposition, getFilenameFromContentDisposition, resolveStandardBodyHint } from '@standardserver/core'
 import { isAsyncIteratorObject, parseEmptyableJSON, stringifyJSON } from '@standardserver/shared'
 import { toAsyncIteratorObject, toEventStream } from './event-stream'
 
@@ -23,14 +23,6 @@ export async function toStandardBody(re: Request | Response, options?: ToStandar
     return undefined
   }
 
-  // request.body might be null if the method is GET, HEAD, or other methods.
-  // WARNING: response.body over fetch is almost always a stream,
-  // even if the standard-server response body is undefined.
-  // WARNING: React Native fetch body might not exist (undefined), so we need to explicitly check for null.
-  if (hint === null && re.body === null) {
-    return undefined
-  }
-
   if (re.bodyUsed) {
     // native fetch error use TypeError
     throw new TypeError('Failed to read body: body stream already read')
@@ -97,8 +89,8 @@ export function toFetchBody(
   headers = { ...headers }
 
   if (body instanceof ReadableStream) {
-    // Explicitly set the body hint to avoid misidentification
-    // when the stream is empty, the length is predictable, or the content type is common.
+    // Always set the body hint: the length of a stream is unknown here, but the transport
+    // can still send a content-length (an empty stream), which reads back as a file.
     headers['standard-server'] ??= 'octet-stream' satisfies StandardBodyHint
     // content-type should be set when body is present
     headers['content-type'] ??= 'application/octet-stream'
@@ -107,21 +99,24 @@ export function toFetchBody(
   }
 
   if (body instanceof Blob) {
-    // Explicitly set the body hint to avoid misidentification
-    // when the file size is NaN or the content type is common.
-    headers['standard-server'] ??= 'file' satisfies StandardBodyHint // A File is also a Blob
-
     headers['content-type'] = body.type
     // FIX: Bun returns `undefined` for an empty File name, despite the spec requiring a string
     headers['content-disposition'] ??= generateContentDisposition(body instanceof File ? body.name ?? '' : 'blob')
 
     // BunS3 can use NaN for the size
-    if (!Number.isFinite(body.size)) {
-      return [body.stream(), headers]
+    const hasKnownSize = Number.isFinite(body.size)
+
+    if (hasKnownSize) {
+      headers['content-length'] = body.size.toString()
     }
 
-    headers['content-length'] = body.size.toString()
-    return [body, headers]
+    // Only set the body hint when the headers don't already resolve to a file.
+    // An empty body always needs it: senders can drop the content-type or content-length if they know the body is empty (e.g. bun, deno)
+    if (headers['standard-server'] === undefined && (body.size === 0 || resolveStandardBodyHint(headers) !== 'file')) {
+      headers['standard-server'] = 'file' satisfies StandardBodyHint // A File is also a Blob
+    }
+
+    return [hasKnownSize ? body : body.stream(), headers]
   }
 
   headers['standard-server'] = undefined

packages/node/src/body.test.ts

@@ -499,7 +499,6 @@ describe('toNodeHttpBody', () => {
       'content-length': '3',
       'content-type': 'application/pdf',
       'x-custom-header': 'custom-value',
-      'standard-server': 'file',
     })
 
     expect(generateContentDispositionSpy).toHaveBeenCalledTimes(1)
@@ -527,7 +526,6 @@ describe('toNodeHttpBody', () => {
       'content-length': '3',
       'content-type': 'application/pdf',
       'x-custom-header': 'custom-value',
-      'standard-server': 'file',
     })
 
     expect(generateContentDispositionSpy).toHaveBeenCalledTimes(1)
@@ -554,7 +552,6 @@ describe('toNodeHttpBody', () => {
       'content-length': '3',
       'content-type': 'application/pdf',
       'x-custom-header': 'custom-value',
-      'standard-server': 'file',
     })
 
     expect(generateContentDispositionSpy).toHaveBeenCalledTimes(0)
@@ -568,6 +565,40 @@ describe('toNodeHttpBody', () => {
     expect(await resBlob.text()).toBe('foo')
   })
 
+  it('blob with common content-type', async () => {
+    const blob = new Blob(['foo'], { type: 'application/json' })
+
+    generateContentDispositionSpy.mockReturnValue('__mocked__')
+
+    const [body, headers] = toNodeHttpBody(blob, baseHeaders, {})
+
+    expect(body).toBeInstanceOf(Readable)
+    expect(headers).toEqual({
+      'content-disposition': '__mocked__',
+      'content-length': '3',
+      'content-type': 'application/json',
+      'x-custom-header': 'custom-value',
+      'standard-server': 'file',
+    })
+  })
+
+  it('empty blob without content-type', async () => {
+    const blob = new Blob([])
+
+    generateContentDispositionSpy.mockReturnValue('__mocked__')
+
+    const [body, headers] = toNodeHttpBody(blob, baseHeaders, {})
+
+    expect(body).toBeInstanceOf(Readable)
+    expect(headers).toEqual({
+      'content-disposition': '__mocked__',
+      'content-length': '0',
+      'content-type': '',
+      'x-custom-header': 'custom-value',
+      'standard-server': 'file',
+    })
+  })
+
   it('file with size=nan', async () => {
     const file = new File(['foo'], 'foo.pdf', { type: 'application/pdf' })
     Object.defineProperty(file, 'size', { value: Number.NaN })

packages/node/src/body.ts

@@ -4,7 +4,7 @@ import type { ToEventStreamOptions } from './event-stream'
 import type { NodeHttpRequest } from './types'
 import { Buffer } from 'node:buffer'
 import { Readable } from 'node:stream'
-import { flattenStandardHeader, generateContentDisposition, getFilenameFromContentDisposition } from '@standardserver/core'
+import { flattenStandardHeader, generateContentDisposition, getFilenameFromContentDisposition, resolveStandardBodyHint } from '@standardserver/core'
 import { isAsyncIteratorObject, parseEmptyableJSON, stringifyJSON } from '@standardserver/shared'
 import { toAsyncIteratorObject, toEventStream } from './event-stream'
 import { toStandardMethod } from './method'
@@ -105,8 +105,8 @@ export function toNodeHttpBody(
   headers = { ...headers }
 
   if (body instanceof ReadableStream) {
-    // Explicitly set the body hint to avoid misidentification
-    // when the stream is empty, the length is predictable, or the content type is common.
+    // Always set the body hint: the length of a stream is unknown here, but the transport
+    // can still send a content-length (an empty stream), which reads back as a file.
     headers['standard-server'] ??= 'octet-stream' satisfies StandardBodyHint
 
     // content-type is required when body is present
@@ -116,10 +116,6 @@ export function toNodeHttpBody(
   }
 
   if (body instanceof Blob) {
-    // Explicitly set the body hint to avoid misidentification
-    // when the file size is NaN or the content type is common.
-    headers['standard-server'] ??= 'file' satisfies StandardBodyHint // A File is also a Blob
-
     headers['content-type'] = body.type
     headers['content-disposition'] ??= generateContentDisposition(body instanceof File ? body.name : 'blob')
 
@@ -128,6 +124,12 @@ export function toNodeHttpBody(
       headers['content-length'] = body.size.toString()
     }
 
+    // Only set the body hint when the headers don't already resolve to a file.
+    // An empty body always needs it: senders can drop the content-type or content-length if they know the body is empty (e.g. bun, deno)
+    if (headers['standard-server'] === undefined && (body.size === 0 || resolveStandardBodyHint(headers) !== 'file')) {
+      headers['standard-server'] = 'file' satisfies StandardBodyHint // A File is also a Blob
+    }
+
     return [Readable.fromWeb(body.stream()), headers]
   }