add simple admin service

local-admin/src/shared/static/serveFile.mjs

@@ -0,0 +1,44 @@
+import { createReadStream } from 'node:fs';
+import { stat } from 'node:fs/promises';
+import { extname } from 'node:path';
+import { httpError } from '../http/httpError.mjs';
+import { mimeTypes } from './mimeTypes.mjs';
+import { resolveInside } from './resolveInside.mjs';
+
+export async function serveFile(response, root, pathname, method) {
+  const filePath = resolveInside(root, pathname);
+
+  if (!filePath) {
+    throw httpError(403, 'Forbidden');
+  }
+
+  const fileStat = await getFileStat(filePath);
+
+  response.writeHead(200, {
+    'Content-Length': fileStat.size,
+    'Content-Type': mimeTypes[extname(filePath).toLowerCase()] || 'application/octet-stream',
+    'X-Content-Type-Options': 'nosniff',
+  });
+
+  if (method === 'HEAD') {
+    response.end();
+    return;
+  }
+
+  createReadStream(filePath).pipe(response);
+}
+
+async function getFileStat(filePath) {
+  let fileStat;
+  try {
+    fileStat = await stat(filePath);
+  } catch {
+    throw httpError(404, 'Not found');
+  }
+
+  if (!fileStat.isFile()) {
+    throw httpError(404, 'Not found');
+  }
+
+  return fileStat;
+}