fix(runtime/js/http): Correctly parse user response headers (denoland…

…#10076)

cli/tests/unit/http_test.ts

@@ -13,7 +13,7 @@ unitTest({ perms: { net: true } }, async function httpServerBasic() {
  const httpConn = Deno.serveHttp(conn);
  for await (const { request, respondWith } of httpConn) {
  assertEquals(await request.text(), "");
- respondWith(new Response("Hello World"));
+ respondWith(new Response("Hello World", { headers: { "foo": "bar" } }));
  }
  break;
  }
@@ -24,6 +24,7 @@ unitTest({ perms: { net: true } }, async function httpServerBasic() {
  });
  const text = await resp.text();
  assertEquals(text, "Hello World");
+ assertEquals(resp.headers.get("foo"), "bar");
  await promise;
 });
 

runtime/js/40_http.js

@@ -9,15 +9,6 @@
  const core = window.Deno.core;
  const { ReadableStream } = window.__bootstrap.streams;
 
- function flatEntries(obj) {
- const entries = [];
- for (const key in obj) {
- entries.push(key);
- entries.push(obj[key]);
- }
- return entries;
- }
-
  function serveHttp(conn) {
  const rid = Deno.core.jsonOpSync("op_http_start", conn.rid);
  return new HttpConn(rid);
@@ -104,12 +95,14 @@
  );
  }
 
- function respond(responseSenderRid, resp, zeroCopyBuf) {
- return Deno.core.jsonOpSync("op_http_response", [
- responseSenderRid,
- resp.status ?? 200,
- flatEntries(resp.headers ?? {}),
- ], zeroCopyBuf);
+ /** IMPORTANT: Equivalent to `Array.from(headers).flat()` but more performant.
+ * Please preserve. */
+ function flattenHeaders(headers) {
+ const array = [];
+ for (const pair of headers) {
+ array.push(pair[0], pair[1]);
+ }
+ return array;
  }
 
  function createRespondWith(responseSenderRid, connRid) {
@@ -136,11 +129,11 @@
  zeroCopyBuf = null;
  }
 
- const responseBodyRid = respond(
+ const responseBodyRid = Deno.core.jsonOpSync("op_http_response", [
  responseSenderRid,
- resp,
- zeroCopyBuf,
- );
+ resp.status ?? 200,
+ flattenHeaders(resp.headers),
+ ], zeroCopyBuf);
 
  // If `respond` returns a responseBodyRid, we should stream the body
  // to that resource.