fix: file streaming for multipart bodies (#7998)

packages/bruno-tests/src/file-binary/index.js

@@ -0,0 +1,70 @@
+const express = require('express');
+const crypto = require('crypto');
+const router = express.Router();
+
+// Capture raw bytes regardless of content-type so we can verify the upload byte-exact.
+// Mounted with its own raw parser (not the global JSON/text parsers) so a
+// JSON content-type with a file body still arrives as a Buffer instead of being
+// pre-parsed and silently size-truncated.
+router.use(express.raw({ type: '*/*', limit: '200mb' }));
+
+// The bug we're guarding against produces a tiny JSON envelope describing a
+// Node fs.ReadStream (fields like fd, flags, _readableState). Detect that
+// shape so any regression flips this flag to true.
+const detectSerializedNodeStream = (firstBytesUtf8) => {
+  try {
+    const trimmed = firstBytesUtf8.trim();
+    if (!trimmed.startsWith('{')) return false;
+    const parsed = JSON.parse(trimmed);
+    return Boolean(
+      parsed && typeof parsed === 'object' && '_readableState' in parsed && 'flags' in parsed
+    );
+  } catch (e) {
+    return false;
+  }
+};
+
+const buildResponse = (req) => {
+  const buf = Buffer.isBuffer(req.body) ? req.body : Buffer.alloc(0);
+  const firstBytesUtf8 = buf.slice(0, 256).toString('utf8');
+  return {
+    method: req.method,
+    contentType: req.headers['content-type'] || null,
+    contentLengthHeader: req.headers['content-length'] || null,
+    transferEncoding: req.headers['transfer-encoding'] || null,
+    bytesReceived: buf.length,
+    sha256: crypto.createHash('sha256').update(buf).digest('hex'),
+    firstBytesUtf8,
+    firstBytesHex: buf.slice(0, 128).toString('hex'),
+    looksLikeSerializedNodeStream: detectSerializedNodeStream(firstBytesUtf8)
+  };
+};
+
+// JSON content-type endpoint — this is the original bug repro path.
+// Pre-fix, large files sent here arrived as a ~342-byte serialization of the
+// Node fs.ReadStream object instead of the file bytes.
+router.post('/binary-upload-json', (req, res) => {
+  const contentType = req.headers['content-type'] || '';
+  if (!contentType.toLowerCase().includes('json')) {
+    return res.status(415).json({
+      error: 'Expected a content-type containing "json"',
+      contentType
+    });
+  }
+  return res.json(buildResponse(req));
+});
+
+// Octet-stream content-type endpoint — the non-JSON branch of the
+// interpolation guard. Should always have worked, kept as a control test.
+router.post('/binary-upload-octet-stream', (req, res) => {
+  const contentType = (req.headers['content-type'] || '').toLowerCase();
+  if (contentType !== 'application/octet-stream') {
+    return res.status(415).json({
+      error: 'Expected content-type: application/octet-stream',
+      contentType
+    });
+  }
+  return res.json(buildResponse(req));
+});
+
+module.exports = router;