refactor: separate Overpass and installation services

server/providers/common/request.js

@@ -0,0 +1,36 @@
+
+/** Read a request body with a hard byte cap; throws { code:'BODY_TOO_LARGE' } past the cap. */
+async function readRequestBodyCapped(req, maxBytes) {
+  const chunks = [];
+  let total = 0;
+  for await (const chunk of req) {
+    total += chunk.length;
+    if (total > maxBytes) {
+      const err = new Error('Request body too large');
+      err.code = 'BODY_TOO_LARGE';
+      throw err;
+    }
+    chunks.push(chunk);
+  }
+  return Buffer.concat(chunks);
+}
+
+function readRequestBody(req, maxBytes = 1024 * 1024) {
+  return new Promise((resolve, reject) => {
+    let total = 0;
+    const chunks = [];
+    req.on('data', (chunk) => {
+      total += chunk.length;
+      if (total > maxBytes) {
+        reject(new Error(`Request body exceeds ${maxBytes} bytes`));
+        req.destroy();
+        return;
+      }
+      chunks.push(chunk);
+    });
+    req.on('end', () => resolve(Buffer.concat(chunks).toString('utf8')));
+    req.on('error', reject);
+  });
+}
+
+export { readRequestBodyCapped, readRequestBody };