fix(ext/http): skip auto-compression if content-encoding present (den…

…oland#14641)

Regression from denoland#14552

cli/tests/unit/http_test.ts

@@ -1978,6 +1978,64 @@ Deno.test({
  },
 });
 
+Deno.test({
+ name: "http server custom content-encoding is left untouched",
+ permissions: { net: true, run: true },
+ async fn() {
+ const hostname = "localhost";
+ const port = 4501;
+ let contentLength: string;
+
+ async function server() {
+ const listener = Deno.listen({ hostname, port });
+ const tcpConn = await listener.accept();
+ const httpConn = Deno.serveHttp(tcpConn);
+ const e = await httpConn.nextRequest();
+ assert(e);
+ const { request, respondWith } = e;
+ assertEquals(request.headers.get("Accept-Encoding"), "deflate, gzip");
+ const body = new Uint8Array([3, 1, 4, 1]);
+ contentLength = String(body.length);
+ const response = new Response(
+ body,
+ {
+ headers: {
+ "content-length": contentLength,
+ "content-encoding": "arbitrary",
+ },
+ },
+ );
+ await respondWith(response);
+ httpConn.close();
+ listener.close();
+ }
+
+ async function client() {
+ const url = `https://${hostname}:${port}/`;
+ const cmd = [
+ "curl",
+ "-i",
+ "--request",
+ "GET",
+ "--url",
+ url,
+ // "--compressed", // Windows curl does not support --compressed
+ "--header",
+ "Accept-Encoding: deflate, gzip",
+ ];
+ const proc = Deno.run({ cmd, stdout: "piped", stderr: "null" });
+ const status = await proc.status();
+ assert(status.success);
+ const output = decoder.decode(await proc.output());
+ assert(output.includes("vary: Accept-Encoding\r\n"));
+ assert(output.includes("content-encoding: arbitrary\r\n"));
+ proc.close();
+ }
+
+ await Promise.all([server(), client()]);
+ },
+});
+
 Deno.test("upgradeHttp tcp", async () => {
  async function client() {
  const tcpConn = await Deno.connect({ port: 4501 });

ext/http/lib.rs

@@ -680,8 +680,11 @@ fn should_compress(headers: &hyper::HeaderMap) -> bool {
  // indicates the contents of the body were negotiated based directly
  // with the user code and we can't compress the response
  let content_range = headers.contains_key(hyper::header::CONTENT_RANGE);
+ // assume body is already compressed if Content-Encoding header present, thus avoid recompressing
+ let is_precompressed = headers.contains_key(hyper::header::CONTENT_ENCODING);
 
  !content_range
+ && !is_precompressed
  && !cache_control_no_transform(headers).unwrap_or_default()
  && headers
  .get(hyper::header::CONTENT_TYPE)