fix(proxy): skip empty passthrough body streams (#854)

Author: harlan-zw

packages/script/src/runtime/server/proxy-handler.ts

@@ -520,7 +520,7 @@ export default defineEventHandler(async (event) => {
 
 // Resolve the fetch body: passthrough streams the raw request, otherwise serialize
 letfetchBody: BodyInit|undefined
-if(passthroughBody){
+if(passthroughBody&&originalHeaders['content-length']!=='0'){
 fetchBody=getRequestWebStream(event)asBodyInit|undefined
 }
 elseif(body!==undefined){
@@ -538,7 +538,7 @@ export default defineEventHandler(async (event) => {
 credentials: 'omit',// Don't send cookies to third parties
 signal: controller.signal,
 redirect: 'manual',
-duplex: passthroughBody ? 'half' : undefined,
+duplex: fetchBodyinstanceofReadableStream ? 'half' : undefined,
 }
 response=awaitnetwork.fetch(targetUrl,requestInit)
 clearTimeout(timeoutId)

test/unit/proxy-handler-body.test.ts

@@ -40,6 +40,8 @@ describe('proxy handler request bodies (#836)', () => {
 letcapturedBody=Buffer.alloc(0)
 letcapturedContentLength: string|undefined
 letcapturedContentType: string|undefined
+letcapturedFetchBody: BodyInit|null|undefined
+letcapturedFetchDuplex: 'half'|undefined
 letcapturedUrl=''
 letreleaseStream: (()=>void)|undefined
 constrealFetch=globalThis.fetch
@@ -81,6 +83,8 @@ describe('proxy handler request bodies (#836)', () => {
 constrequestUrl=inputinstanceofRequest ? input.url : String(input)
 consturl=newURL(requestUrl)
 if(url.hostname==='upstream.test'){
+capturedFetchBody=init?.body
+capturedFetchDuplex=(initasRequestInit&{duplex?: 'half'}|undefined)?.duplex
 constredirected=`http://127.0.0.1:${upstreamPort}${url.pathname}${url.search}`
 returnrealFetch(redirected,init)
 }
@@ -98,6 +102,8 @@ describe('proxy handler request bodies (#836)', () => {
 capturedBody=Buffer.alloc(0)
 capturedContentLength=undefined
 capturedContentType=undefined
+capturedFetchBody=undefined
+capturedFetchDuplex=undefined
 capturedUrl=''
 releaseStream=undefined
 })
@@ -120,10 +126,28 @@ describe('proxy handler request bodies (#836)', () => {
 })
 
 expect(response.status).toBe(200)
+expect(capturedFetchBody).toBeInstanceOf(ReadableStream)
+expect(capturedFetchDuplex).toBe('half')
 expect(capturedBody.equals(compressed)).toBe(true)
 expect(capturedContentType).toBe('text/plain')
 })
 
+it('forwards an explicitly empty opaque POST without a body stream (#853)',async()=>{
+constresponse=awaitrealFetch(`http://127.0.0.1:${proxyPort}/_scripts/p/upstream.test/measurement/conversion`,{
+method: 'POST',
+headers: {
+'content-length': '0',
+'content-type': 'text/plain;charset=UTF-8',
+},
+})
+
+expect(response.status).toBe(200)
+expect(capturedFetchBody).toBeUndefined()
+expect(capturedFetchDuplex).toBeUndefined()
+expect(capturedBody).toHaveLength(0)
+expect(capturedContentLength).toBe('0')
+})
+
 it('rejects an allowlisted local network target before the upstream fetch',async()=>{
 constresponse=awaitrealFetch(`http://127.0.0.1:${proxyPort}/_scripts/p/127.0.0.1/private`)