whiteboard-body.ts

whiteboard-body.tsapps/api/src/common/whiteboard-body.tsraw ← common2,733 B← Back to the app
1import type { NextFunction, Request, Response } from "express";
2import { v4 as uuid } from "uuid";
3import { API_PREFIX, MAX_WHITEBOARD_BODY_BYTES } from "../constants.js";
4 
5/**
6 * T-167 — route-scoped body parser for `PUT /pages/:id/whiteboard`.
7 *
8 * A canvas save is a single JSON document (the whole canvas), and a large
9 * board (the 2,000-object render/perf gate) can exceed the global 256 KB JSON
10 * ceiling. This mirrors `csv-import-body.ts`: it buffers ONLY the canvas-save
11 * route (everything else falls through to the 256 KB parser), 413s past
12 * `MAX_WHITEBOARD_BODY_BYTES`, and sets `req.body` + `req._body = true` so the
13 * downstream global parser skips. It must be registered BEFORE the
14 * `app.useBodyParser("json", …)` calls (main.ts + integration helper).
15 */
16 
17const CANVAS_SAVE_PATH = new RegExp(
18  `^/${API_PREFIX.replace(/\//g, "\\/")}/pages/[^/]+/whiteboard$`,
19);
20 
21function envelope(req: Request, res: Response, code: string, status: number, message: string): void {
22  const requestId = (req.headers["x-request-id"] as string | undefined) ?? uuid();
23  req.id = requestId;
24  res.setHeader("x-request-id", requestId);
25  res.status(status).json({ error: { code, message, requestId } });
26}
27 
28export function whiteboardBodyParser(req: Request, res: Response, next: NextFunction): void {
29  if (req.method !== "PUT" || !CANVAS_SAVE_PATH.test(req.path)) {
30    next();
31    return;
32  }
33  // Fast path: a declared Content-Length over the cap 413s without buffering.
34  const declared = Number(req.headers["content-length"] ?? 0);
35  if (declared > MAX_WHITEBOARD_BODY_BYTES) {
36    req.resume();
37    envelope(req, res, "PAYLOAD_TOO_LARGE", 413, `Whiteboard canvas exceeds the ${MAX_WHITEBOARD_BODY_BYTES} byte limit.`);
38    return;
39  }
40  const chunks: Buffer[] = [];
41  let size = 0;
42  let done = false;
43  const finish = (err?: unknown): void => {
44    if (done) return;
45    done = true;
46    if (err) {
47      next(err);
48      return;
49    }
50    const raw = Buffer.concat(chunks);
51    req.rawBody = raw;
52    try {
53      req.body = raw.length > 0 ? JSON.parse(raw.toString("utf8")) : null;
54    } catch {
55      envelope(req, res, "VALIDATION_ERROR", 400, "Request body must be valid JSON.");
56      return;
57    }
58    (req as unknown as Record<string, unknown>)._body = true; // stop the downstream 256 KB parser
59    next();
60  };
61  req.on("data", (chunk: Buffer) => {
62    size += chunk.length;
63    if (size > MAX_WHITEBOARD_BODY_BYTES) {
64      done = true;
65      req.resume();
66      envelope(req, res, "PAYLOAD_TOO_LARGE", 413, `Whiteboard canvas exceeds the ${MAX_WHITEBOARD_BODY_BYTES} byte limit.`);
67      return;
68    }
69    chunks.push(chunk);
70  });
71  req.on("end", () => finish());
72  req.on("error", (err) => finish(err));
73}
74