358 lines
13 KiB
Markdown
358 lines
13 KiB
Markdown
# File Drop (VYBECODED)
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A minimal, self-hosted private file hosting service built with **Bun** and
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**TypeScript**. Upload a file, get a secret, unguessable download link. Files are
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stored on the local filesystem and expire after 48 hours.
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Everything lives on disk — the filesystem is the source of truth. There is no
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database, no object storage, and no queue. Expired files are swept automatically.
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## Features
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- Drag & drop / file-picker uploads with progress, straight from the browser.
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- **Required per-file password**: every download is protected by a password.
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- Storage on the local filesystem; files survive restarts.
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- A cryptographically secure, unguessable download key for every file.
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- Streaming uploads and downloads — no full buffering in RAM, large files work.
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- Configurable maximum upload size (`413` when exceeded, default 10GB).
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- Files **auto-expire after 48 hours** and are removed automatically.
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- Authenticated deletion (possession of the file's secret key is required).
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- Rate-limited download/delete endpoints to blunt brute force.
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- Zero runtime dependencies (Bun is the only runtime).
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## Requirements
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- [Bun](https://bun.sh) >= 1.1 (developed and tested against 1.3).
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- Any platform Bun runs on (Linux, macOS, Windows).
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## Installation
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```bash
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bun install
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```
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There are no runtime dependencies; the only packages are dev-time
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(`typescript`, `@types/bun`) used for type-checking.
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## Configuration
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All configuration is via environment variables. Bun auto-loads `.env`, so you
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can copy the example and edit it:
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```bash
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cp .env.example .env
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```
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| Variable | Default | Description |
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| ---------------------- | ------------- | ----------------------------------------------------------------- |
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| `HOST` | `0.0.0.0` | Bind address. |
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| `PORT` | `3000` | Bind port. |
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| `STORAGE_DIR` | `./storage` | Directory where files + metadata are stored (relative to CWD). |
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| `MAX_FILE_SIZE` | `10GB` | Max upload size. Units: `B`, `KB`, `MB`, `GB`, `TB` (or plain int). |
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| `MAX_STORAGE_USAGE` | `0.5` | Max fraction (0.0–1.0) of the storage disk that may be used; uploads are rejected with `503 try again later` above this. |
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| `FILE_TTL_MS` | `172800000` | Milliseconds before an upload expires and is deleted (48 hours, hard maximum). |
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| `RATE_LIMIT_ENABLED` | `1` | Enable per-IP rate limiting on `/(key)` and `/api/files/`. |
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| `RATE_LIMIT_MAX` | `300` | Max requests per IP per window. |
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| `RATE_LIMIT_WINDOW_MS` | `60000` | Rate-limit window length in ms. |
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| `TRUST_PROXY` | `0` | Set `1` only behind a proxy that sets `X-Forwarded-For`. |
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## Running locally
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```bash
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bun run start # production (env-driven)
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bun run dev # watch mode, restarts on change
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```
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Then open http://localhost:3000.
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## Usage
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1. Open the site.
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2. Drop `example.zip` (or click to pick a file).
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3. The server stores it and returns a URL like
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`https://files.example.com/8fJ...random-secret...`.
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4. Copy the URL. Anyone possessing it can download the file — **after entering
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the password you set at upload**. Nobody without the secret URL and the
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password can download it.
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5. The file is removed automatically after 48 hours, or earlier by explicit
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deletion.
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## Filesystem layout
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```
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storage/
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├── .secret # server signing secret (0600), auto-generated
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├── files/
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│ ├── <file-id> # the raw uploaded bytes
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│ └── <file-id>
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└── metadata/
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├── <file-id>.json # metadata for each file
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└── <file-id>.json
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```
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Example metadata record (`storage/metadata/<file-id>.json`):
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```json
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{
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"id": "YOWJyhDXxhe3-L8MpEFBbA",
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"originalName": "example.zip",
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"size": 123456,
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"mimeType": "application/zip",
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"downloadKeyHash": "669870d2e66b57edbd5128d85d803db0bed262efde61ef1f9e6dcef5c5ffa166",
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"createdAt": "2026-08-14T22:08:36.730Z"
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}
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```
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Only a SHA-256 **hash** of the download key is stored — the plaintext key exists
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only inside the URL shown to the uploader. If a download password is set, only
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its scrypt hash is stored (see [password protection](#password-protection)).
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The server signing secret for download cookies lives in `storage/.secret`
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(`0600`), created on first start and reused across restarts.
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Uploads are first streamed to a `<file-id>.part` temp file and atomically renamed
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into place on completion. At startup the server sweeps for orphans (a file
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without metadata or metadata without a file, plus leftover `.part` files) and
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removes them. This is consistency repair, not expiration — real files are never
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touched.
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## API
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### `POST /api/upload`
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Multipart/form-data with a `file` field and a **required** `password` field
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(this is what the web UI uses). Uploads without a password are rejected with
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`400`.
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```bash
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curl -F "password=hunter2" -F "[email protected]" http://localhost:3000/api/upload
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```
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```json
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{
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"id": "xmK5lLMRErlN",
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"key": "xmK5lLMRErlN",
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"url": "/xmK5lLMRErlN",
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"originalName": "example.zip",
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"size": 123456,
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"protected": true
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}
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```
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`id` and `key` are the same 12-character base64url token (~72 bits of entropy);
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the short length keeps share URLs tidy, and the required password adds a second
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factor of protection.
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### `GET /:key` (also `HEAD`)
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The download URL is just the key at the site root (`https://host/xmK5lLMRErlN`).
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The legacy `/d/:key` form still works as an alias. Every file is
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password-protected: without a valid auth cookie the server shows a password
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prompt; a wrong or non-existent key returns a generic `404`.
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```bash
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curl -O http://localhost:3000/xmK5lLMRErlN # prompts for password first
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```
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### Password protection
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Every file requires its password:
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1. `GET /:key` returns a small HTML password form.
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2. The browser submits it to `POST /api/auth/:key` with `password=...`.
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3. On success the server sets a short-lived (30 min), HttpOnly, SameSite=Lax,
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signed cookie and redirects back to `/:key`, which then streams the file.
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```bash
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curl -c cookies.txt -X POST -d "password=hunter2" http://localhost:3000/api/auth/:key
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curl -b cookies.txt -O http://localhost:3000/:key
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```
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The cookie is signed with a server secret (`storage/.secret`) so it cannot be
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forged, and it survives server restarts. Without it, a file is never
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downloadable — not even by the uploader.
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### `DELETE /api/files/:id`
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Permanently deletes the file and its metadata. The correct download key must be
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sent in the `X-Delete-Key` header — proving you hold the secret.
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```bash
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curl -X DELETE -H "X-Delete-Key: YOWJyh...7OQ" http://localhost:3000/api/files/YOWJyhDXxhe3-L8MpEFBbA
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```
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### `GET /api/health`
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```json
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{ "status": "ok", "uptimeSeconds": 42 }
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```
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### Status codes
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`400` invalid request · `404` unknown/invalid key · `413` file too large ·
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`429` rate limited · `500` internal error. Errors are generic JSON and never leak
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paths or stack traces.
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## Security model
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- **Secrets.** Each file gets a fresh 72-bit (9 random bytes) base64url key via
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`crypto.randomBytes`, used as both the share id and the download key. Keys are
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encoded base64url; guessing one is infeasible at scale, and the required
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password is an added second factor. No timestamps, incrementing ids,
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`Math.random()`, or filenames are ever used as secrets.
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- **At-rest.** Only a SHA-256 hash of the key is persisted. Comparisons use
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constant-time `timingSafeEqual`.
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- **Passwords.** Every file has a password stored only as an **scrypt** hash
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(salted), never in plaintext. Successful entry mints a short-lived HMAC-signed
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cookie, so access is granted by the server and cannot be forged.
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- **Path safety.** Filesystem paths are built only from server-generated,
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regex-validated ids (`^[A-Za-z0-9_-]{22}$`). The original filename is metadata
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only and is sanitized (basename, control/null bytes stripped) before being
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stored or emitted in `Content-Disposition`. Path traversal, `../`, encoded
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traversal, null bytes, and symlink injection via user input are not possible.
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Downloads additionally refuse symlinks (`lstat`) as defense in depth.
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- **MIME / XSS.** Downloads are sent as `Content-Disposition: attachment` (browsers
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download rather than render) with `X-Content-Type-Options: nosniff`, so a spoofed
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`text/html` or `image/svg+xml` cannot execute scripts.
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- **Secrecy of URLs.** All responses carry `Referrer-Policy: no-referrer`, and
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downloads use `Cache-Control: private, no-store`, so the keyed URL is not leaked
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to referrers or shared caches.
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- **Isolation.** Only the frontend, health, upload, download, and delete routes
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exist; everything else is a `404`. `storage/` is never served.
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- **Brute force.** Download and delete endpoints are rate-limited per client IP.
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Set `TRUST_PROXY=1` only when a proxy sets `X-Forwarded-For`, otherwise clients
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can spoof it.
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- **Log hygiene.** Logs record file ids, sizes, and sanitized names — never
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download keys or full private URLs.
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- **Overwrite.** Random ids make collisions effectively impossible; uploads write
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to a unique `.part` file and atomically rename.
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## Reverse proxy
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The app does not handle TLS; put nginx, Caddy, or Cloudflare in front. It works
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behind any proxy because it uses relative URLs and doesn't require HTTPS
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termination.
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Important: large uploads only work if your proxy does **not** buffer the request
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body.
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### nginx
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```nginx
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server {
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listen 80;
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server_name files.example.com;
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client_max_body_size 11g; # >= MAX_FILE_SIZE
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proxy_request_buffering off; # stream uploads, don't buffer
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location / {
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proxy_pass http://127.0.0.1:3000;
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proxy_set_header Host $host;
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proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
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proxy_read_timeout 300s; # slow/large downloads
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}
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}
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```
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### Caddy
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```
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files.example.com {
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reverse_proxy 127.0.0.1:3000
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request_body {
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max_size 6GB
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}
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}
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```
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> Cloudflare note: the free plan caps uploads at ~100MB (and downloads at
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> ~100MB/500MB depending on plan). For larger files, bypass the proxy for
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> `/api/upload` and `/d/` (e.g. a cache rule or origin rule) so traffic hits the
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> origin directly.
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## Production deployment
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> Follow the step-by-step **[HOSTING.md](./HOSTING.md)** guide for a complete
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> VPS setup (Bun install, systemd, nginx/Caddy + TLS, firewall, Cloudflare,
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> backups, troubleshooting). Summary below.
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```bash
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# 1. install bun and copy the project
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mkdir -p /opt/filehost && cp -r . /opt/filehost && cd /opt/filehost
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bun install
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# 2. create a dedicated user and writable storage
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useradd --system --home /opt/filehost filehost
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mkdir -p /opt/filehost/storage && chown -R filehost:filehost /opt/filehost
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# 3. configure
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cp .env.example /opt/filehost/.env
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# edit .env (PORT, STORAGE_DIR, MAX_FILE_SIZE, TRUST_PROXY, ...)
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# 4. install the systemd unit (see deploy/filehost.service)
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cp deploy/filehost.service /etc/systemd/system/filehost.service
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systemctl daemon-reload
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systemctl enable --now filehost
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systemctl status filehost
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# 5. put a reverse proxy in front (above)
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```
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## Backup
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Backup the whole `storage/` directory. Because files and metadata live in the
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filesystem, a simple `tar` gives you a consistent, restorable snapshot:
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```bash
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tar -czf filehost-backup-$(date +%F).tar.gz /opt/filehost/storage
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```
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A nightly cron job:
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```cron
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0 2 * * * tar -czf /var/backups/filehost-$(date +\%F).tar.gz -C /opt/filehost/storage .
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```
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To restore: stop the service, replace the `storage/` directory, start the
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service. Files that have their metadata survive; anything incomplete is repaired
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by the startup sweep. For crash-consistency you can stop the service during
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backup (or rely on `tar` on a quiet filesystem). Metadata writes are atomic
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(tmp + rename), so partial records are rare.
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## Running the smoke test
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```bash
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# start the server, then:
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./scripts/smoke-test.sh
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BASE_URL=http://127.0.0.1:3000 ./scripts/smoke-test.sh # explicit URL
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```
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It exercises upload, download, invalid keys, id-only denial, storage isolation,
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Unicode names, path traversal sanitization, a 16MB binary round-trip, and
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authenticated deletion. The same checks performed manually during development
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also included restart persistence, a 256MB streaming round-trip (peak RSS
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~80MB), `413` handling, rate limiting, and log-hygiene (keys never logged).
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## Project layout
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```
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src/
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├── server.ts # entry point: config, routing, static files, startup
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├── config.ts # env parsing + size parsing
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├── storage.ts # filesystem source of truth (save, metadata, delete, sweep)
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├── multipart.ts # streaming multipart parser (no full-body buffering)
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├── security.ts # key generation, hashing, timing-safe compare, sanitization
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├── ratelimit.ts # simple per-IP fixed-window limiter
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├── http.ts # response/error helpers + security headers
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├── log.ts # timestamped logging
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├── routes/
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│ ├── upload.ts # POST /api/upload
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│ ├── download.ts # GET /:key
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│ └── delete.ts # DELETE /api/files/:id
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└── public/ # plain HTML/CSS/JS frontend (no framework)
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```
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Intentionally small: no framework, no DI, no ORM, no repositories. Bun +
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TypeScript + filesystem + a simple frontend + secret URLs.
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