feat: use internal body if available for returning the response in its original form as much as possible

src/listener.ts

@@ -1,7 +1,7 @@
 import type { IncomingMessage, ServerResponse, OutgoingHttpHeaders } from 'node:http'
 import type { Http2ServerRequest, Http2ServerResponse } from 'node:http2'
 import { getAbortController, newRequest } from './request'
-import { cacheKey } from './response'
+import { cacheKey, getInternalBody } from './response'
 import type { CustomErrorHandler, FetchCallback, HttpBindings } from './types'
 import { writeFromReadableStream, buildOutgoingHttpHeaders } from './utils'
 import './globals'
@@ -72,56 +72,61 @@ const responseViaResponseObject = async (
     }
   }
 
-  try {
-    const isCached = cacheKey in res
-    if (isCached) {
-      return responseViaCache(res as Response, outgoing)
-    }
-  } catch (e: unknown) {
-    return handleResponseError(e, outgoing)
+  if (cacheKey in res) {
+    return responseViaCache(res as Response, outgoing)
   }
 
   const resHeaderRecord: OutgoingHttpHeaders = buildOutgoingHttpHeaders(res.headers)
 
-  if (res.body) {
-    try {
-      /**
-       * If content-encoding is set, we assume that the response should be not decoded.
-       * Else if transfer-encoding is set, we assume that the response should be streamed.
-       * Else if content-length is set, we assume that the response content has been taken care of.
-       * Else if x-accel-buffering is set to no, we assume that the response should be streamed.
-       * Else if content-type is not application/json nor text/* but can be text/event-stream,
-       * we assume that the response should be streamed.
-       */
-
-      const {
-        'transfer-encoding': transferEncoding,
-        'content-encoding': contentEncoding,
-        'content-length': contentLength,
-        'x-accel-buffering': accelBuffering,
-        'content-type': contentType,
-      } = resHeaderRecord
-
-      if (
-        transferEncoding ||
-        contentEncoding ||
-        contentLength ||
-        // nginx buffering variant
-        (accelBuffering && regBuffer.test(accelBuffering as string)) ||
-        !regContentType.test(contentType as string)
-      ) {
-        outgoing.writeHead(res.status, resHeaderRecord)
-
-        await writeFromReadableStream(res.body, outgoing)
-      } else {
-        const buffer = await res.arrayBuffer()
-        resHeaderRecord['content-length'] = buffer.byteLength
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const internalBody = getInternalBody(res as any)
+  if (internalBody) {
+    if (internalBody.length) {
+      resHeaderRecord['content-length'] = internalBody.length
+    }
+    outgoing.writeHead(res.status, resHeaderRecord)
+    if (typeof internalBody.source === 'string' || internalBody.source instanceof Uint8Array) {
+      outgoing.end(internalBody.source)
+    } else if (internalBody.source instanceof Blob) {
+      outgoing.end(new Uint8Array(await internalBody.source.arrayBuffer()))
+    } else {
+      await writeFromReadableStream(internalBody.stream, outgoing)
+    }
+  } else if (res.body) {
+    /**
+     * If content-encoding is set, we assume that the response should be not decoded.
+     * Else if transfer-encoding is set, we assume that the response should be streamed.
+     * Else if content-length is set, we assume that the response content has been taken care of.
+     * Else if x-accel-buffering is set to no, we assume that the response should be streamed.
+     * Else if content-type is not application/json nor text/* but can be text/event-stream,
+     * we assume that the response should be streamed.
+     */
+
+    const {
+      'transfer-encoding': transferEncoding,
+      'content-encoding': contentEncoding,
+      'content-length': contentLength,
+      'x-accel-buffering': accelBuffering,
+      'content-type': contentType,
+    } = resHeaderRecord
+
+    if (
+      transferEncoding ||
+      contentEncoding ||
+      contentLength ||
+      // nginx buffering variant
+      (accelBuffering && regBuffer.test(accelBuffering as string)) ||
+      !regContentType.test(contentType as string)
+    ) {
+      outgoing.writeHead(res.status, resHeaderRecord)
+
+      await writeFromReadableStream(res.body, outgoing)
+    } else {
+      const buffer = await res.arrayBuffer()
+      resHeaderRecord['content-length'] = buffer.byteLength
 
-        outgoing.writeHead(res.status, resHeaderRecord)
-        outgoing.end(new Uint8Array(buffer))
-      }
-    } catch (e: unknown) {
-      handleResponseError(e, outgoing)
+      outgoing.writeHead(res.status, resHeaderRecord)
+      outgoing.end(new Uint8Array(buffer))
     }
   } else {
     outgoing.writeHead(res.status, resHeaderRecord)
@@ -173,6 +178,10 @@ export const getRequestListener = (
       }
     }
 
-    return responseViaResponseObject(res, outgoing, options)
+    try {
+      return responseViaResponseObject(res, outgoing, options)
+    } catch (e) {
+      return handleResponseError(e, outgoing)
+    }
   }
 }

src/response.ts

@@ -4,15 +4,22 @@
 import type { OutgoingHttpHeaders } from 'node:http'
 import { buildOutgoingHttpHeaders } from './utils'
 
+interface InternalBody {
+  source: string | Uint8Array | FormData | Blob | null
+  stream: ReadableStream
+  length: number | null
+}
+
 const responseCache = Symbol('responseCache')
+const getResponseCache = Symbol('getResponseCache')
 export const cacheKey = Symbol('cache')
 
 export const GlobalResponse = global.Response
 export class Response {
   #body?: BodyInit | null
-  #init?: ResponseInit
+  #init?: ResponseInit;
 
-  private get cache(): typeof GlobalResponse {
+  [getResponseCache](): typeof GlobalResponse {
     delete (this as any)[cacheKey]
     return ((this as any)[responseCache] ||= new GlobalResponse(this.#body, this.#init))
   }
@@ -24,7 +31,7 @@ export class Response {
       if (cachedGlobalResponse) {
         this.#init = cachedGlobalResponse
         // instantiate GlobalResponse cache and this object always returns value from global.Response
-        this.cache
+        this[getResponseCache]()
         return
       } else {
         this.#init = init.#init
@@ -60,14 +67,14 @@ export class Response {
 ].forEach((k) => {
   Object.defineProperty(Response.prototype, k, {
     get() {
-      return this.cache[k]
+      return this[getResponseCache]()[k]
     },
   })
 })
 ;['arrayBuffer', 'blob', 'clone', 'formData', 'json', 'text'].forEach((k) => {
   Object.defineProperty(Response.prototype, k, {
     value: function () {
-      return this.cache[k]()
+      return this[getResponseCache]()[k]()
     },
   })
 })
@@ -76,3 +83,27 @@ Object.setPrototypeOf(Response.prototype, GlobalResponse.prototype)
 Object.defineProperty(global, 'Response', {
   value: Response,
 })
+
+const stateKey = Reflect.ownKeys(new GlobalResponse()).find(
+  (k) => typeof k === 'symbol' && k.toString() === 'Symbol(state)'
+) as symbol | undefined
+if (!stateKey) {
+  console.warn('Failed to find Response internal state key')
+}
+
+export function getInternalBody(
+  response: Response | typeof GlobalResponse
+): InternalBody | undefined {
+  if (!stateKey) {
+    return
+  }
+
+  if (response instanceof Response) {
+    response = (response as any)[getResponseCache]()
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const state = (response as any)[stateKey] as { body?: InternalBody } | undefined
+
+  return (state && state.body) || undefined
+}

test/server.test.ts

@@ -83,6 +83,88 @@ describe('Basic', () => {
   })
 })
 
+describe('via internal body', () => {
+  const app = new Hono()
+  app.use('*', async (c, next) => {
+    await next()
+
+    // generate internal response object
+    const status = c.res.status
+    if (status > 999) {
+      c.res = new Response('Internal Server Error', { status: 500 })
+    }
+  })
+  app.get('/', () => {
+    const response = new Response('Hello! Node!')
+    return response
+  })
+  app.get('/uint8array', () => {
+    const response = new Response(new Uint8Array([1, 2, 3]), {
+      headers: { 'content-type': 'application/octet-stream' },
+    })
+    return response
+  })
+  app.get('/blob', () => {
+    const response = new Response(new Blob([new Uint8Array([1, 2, 3])]), {
+      headers: { 'content-type': 'application/octet-stream' },
+    })
+    return response
+  })
+  app.get('/readable-stream', () => {
+    const stream = new ReadableStream({
+      async start(controller) {
+        controller.enqueue('Hello!')
+        controller.enqueue(' Node!')
+        controller.close()
+      },
+    })
+    return new Response(stream)
+  })
+
+  const server = createAdaptorServer(app)
+
+  it('Should return 200 response - GET /', async () => {
+    const res = await request(server).get('/')
+    expect(res.status).toBe(200)
+    expect(res.headers['content-type']).toMatch('text/plain')
+    expect(res.headers['content-length']).toMatch('12')
+    expect(res.text).toBe('Hello! Node!')
+  })
+
+  it('Should return 200 response - GET /uint8array', async () => {
+    const res = await request(server).get('/uint8array')
+    expect(res.status).toBe(200)
+    expect(res.headers['content-type']).toMatch('application/octet-stream')
+    expect(res.headers['content-length']).toMatch('3')
+    expect(res.body).toEqual(Buffer.from([1, 2, 3]))
+  })
+
+  it('Should return 200 response - GET /blob', async () => {
+    const res = await request(server).get('/blob')
+    expect(res.status).toBe(200)
+    expect(res.headers['content-type']).toMatch('application/octet-stream')
+    expect(res.headers['content-length']).toMatch('3')
+    expect(res.body).toEqual(Buffer.from([1, 2, 3]))
+  })
+
+  it('Should return 200 response - GET /readable-stream', async () => {
+    const expectedChunks = ['Hello!', ' Node!']
+    const res = await request(server)
+      .get('/readable-stream')
+      .parse((res, fn) => {
+        res.on('data', (chunk) => {
+          const str = chunk.toString()
+          expect(str).toBe(expectedChunks.shift())
+        })
+        res.on('end', () => fn(null, ''))
+      })
+    expect(res.status).toBe(200)
+    expect(res.headers['content-type']).toMatch('text/plain; charset=UTF-8')
+    expect(res.headers['content-length']).toBeUndefined()
+    expect(expectedChunks.length).toBe(0) // all chunks are received
+  })
+})
+
 describe('Routing', () => {
   describe('Nested Route', () => {
     const book = new Hono()