fix(ext/http): reading headers with ongoing body reader (#15161)

cli/tests/unit/http_test.ts

@@ -73,6 +73,68 @@ Deno.test({ permissions: { net: true } }, async function httpServerBasic() {
   await promise;
 });
 
+// https://github.com/denoland/deno/issues/15107
+Deno.test(
+  { permissions: { net: true } },
+  async function httpLazyHeadersIssue15107() {
+    let headers: Headers;
+    const promise = (async () => {
+      const listener = Deno.listen({ port: 2333 });
+      const conn = await listener.accept();
+      listener.close();
+      const httpConn = Deno.serveHttp(conn);
+      const e = await httpConn.nextRequest();
+      assert(e);
+      const { request } = e;
+      request.text();
+      headers = request.headers;
+      httpConn.close();
+    })();
+
+    const conn = await Deno.connect({ port: 2333 });
+    // Send GET request with a body + content-length.
+    const encoder = new TextEncoder();
+    const body =
+      `GET / HTTP/1.1\r\nHost: 127.0.0.1:2333\r\nContent-Length: 5\r\n\r\n12345`;
+    const writeResult = await conn.write(encoder.encode(body));
+    assertEquals(body.length, writeResult);
+    await promise;
+    conn.close();
+    assertEquals(headers!.get("content-length"), "5");
+  },
+);
+
+Deno.test(
+  { permissions: { net: true } },
+  async function httpReadHeadersAfterClose() {
+    const promise = (async () => {
+      const listener = Deno.listen({ port: 2334 });
+      const conn = await listener.accept();
+      listener.close();
+      const httpConn = Deno.serveHttp(conn);
+      const e = await httpConn.nextRequest();
+      assert(e);
+      const { request, respondWith } = e;
+
+      await request.text(); // Read body
+      await respondWith(new Response("Hello World")); // Closes request
+
+      assertThrows(() => request.headers, TypeError, "request closed");
+      httpConn.close();
+    })();
+
+    const conn = await Deno.connect({ port: 2334 });
+    // Send GET request with a body + content-length.
+    const encoder = new TextEncoder();
+    const body =
+      `GET / HTTP/1.1\r\nHost: 127.0.0.1:2333\r\nContent-Length: 5\r\n\r\n12345`;
+    const writeResult = await conn.write(encoder.encode(body));
+    assertEquals(body.length, writeResult);
+    await promise;
+    conn.close();
+  },
+);
+
 Deno.test(
   { permissions: { net: true } },
   async function httpServerGetRequestBody() {