fix(http): handle HEAD requests in serveDir (#7024)

Co-authored-by: Yoshiya Hinosawa <stibium121@gmail.com>

Author: wilkmaciej

http/file_server.ts

@@ -337,6 +337,7 @@ export async function serveFile(
 }
 
 async function serveDirIndex(
+  req: Request,
   dirPath: string,
   options: {
     showDotfiles: boolean;
@@ -406,9 +407,13 @@ async function serveDirIndex(
 
   const headers = createBaseHeaders();
   headers.set(HEADER.ContentType, "text/html; charset=UTF-8");
+  if (req.method === METHOD.Head) {
+    const pageSize = new TextEncoder().encode(page).byteLength;
+    headers.set(HEADER.ContentLength, String(pageSize));
+  }
 
   const status = STATUS_CODE.OK;
-  return new Response(page, {
+  return new Response(req.method === METHOD.Head ? null : page, {
     status,
     statusText: STATUS_TEXT[status],
     headers,
@@ -660,7 +665,7 @@ export async function serveDir(
   req: Request,
   opts: ServeDirOptions = {},
 ): Promise<Response> {
-  if (req.method !== METHOD.Get) {
+  if (req.method !== METHOD.Get && req.method !== METHOD.Head) {
     return createStandardResponse(STATUS_CODE.MethodNotAllowed);
   }
 
@@ -796,7 +801,7 @@ async function createServeDirResponse(
   }
 
   if (showDirListing) { // serve directory list
-    return serveDirIndex(fsPath, { showDotfiles, target, quiet });
+    return serveDirIndex(req, fsPath, { showDotfiles, target, quiet });
   }
 
   return createStandardResponse(STATUS_CODE.NotFound);

http/file_server_test.ts

@@ -1153,6 +1153,55 @@ Deno.test(async function serveFileHeadRequest() {
   assertEquals(res.headers.get("content-length"), "10034");
 });
 
+Deno.test("serveDir() handles HEAD request for a file", async () => {
+  const req = new Request("http://localhost/test_file.txt", {
+    method: "HEAD",
+  });
+  const res = await serveDir(req, serveDirOptions);
+
+  assert(!res.body);
+  assertEquals(res.status, 200);
+  assertEquals(res.statusText, "OK");
+  assertEquals(res.headers.get("content-type"), "text/plain; charset=UTF-8");
+  assertEquals(res.headers.get("content-length"), `${TEST_FILE_SIZE}`);
+  assertEquals(res.headers.get("etag"), TEST_FILE_ETAG);
+  assertEquals(res.headers.get("last-modified"), TEST_FILE_LAST_MODIFIED);
+  assertEquals(res.headers.get("accept-ranges"), "bytes");
+});
+
+Deno.test("serveDir() handles HEAD request for index.html", async () => {
+  const req = new Request(
+    "http://localhost/http/testdata/subdir-with-index/",
+    { method: "HEAD" },
+  );
+  const res = await serveDir(req, { showIndex: true });
+
+  assert(!res.body);
+  assertEquals(res.status, 200);
+  assertEquals(res.headers.get("content-type"), "text/html; charset=UTF-8");
+});
+
+Deno.test("serveDir() handles HEAD request for directory listing", async () => {
+  const req = new Request("http://localhost/", { method: "HEAD" });
+  const res = await serveDir(req, serveDirOptions);
+
+  assert(!res.body);
+  assertEquals(res.status, 200);
+  assertEquals(res.headers.get("content-type"), "text/html; charset=UTF-8");
+  assert(Number(res.headers.get("content-length")) > 0);
+});
+
+Deno.test("serveDir() handles HEAD request for missing file", async () => {
+  const req = new Request("http://localhost/no_such_file.txt", {
+    method: "HEAD",
+  });
+  const res = await serveDir(req, serveDirOptions);
+  await res.body?.cancel();
+
+  assertEquals(res.status, 404);
+  assertEquals(res.statusText, "Not Found");
+});
+
 Deno.test("(unstable) serveDir() serves files without the need of html extension when cleanUrls=true", async () => {
   const req = new Request("http://localhost/hello");
   const res = await unstableServeDir(req, {