@bun-win32/rasapi32

Zero-dependency, zero-overhead Win32 Rasapi32 bindings for Bun on Windows.

Overview

@bun-win32/rasapi32 exposes the rasapi32.dll exports using Bun's FFI. It provides a single class, Rasapi32, which lazily binds native symbols on first use. You can optionally preload a subset or all symbols up-front via Preload().

The bindings are strongly typed for a smooth DX in TypeScript.

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to rasapi32.dll (RAS dial-up, VPN, phonebook entries, connection management, projection info, and statistics).
• In-source docs in structs/Rasapi32.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Rasapi32.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Rasapi32.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/rasapi32

Quick Start

import Rasapi32 from '@bun-win32/rasapi32';

// Optionally bind a subset up-front
Rasapi32.Preload(['RasEnumConnectionsW', 'RasGetErrorStringW']);

// How many RAS (dial-up/VPN) connections are active right now?
const cb = Buffer.alloc(4);
const count = Buffer.alloc(4);
// First call with a NULL buffer: a return of 0 with count 0 means none active.
Rasapi32.RasEnumConnectionsW(null, cb.ptr, count.ptr);
console.log('Active RAS connections: %d', count.readUInt32LE(0));

// Translate a RAS error code (691 = bad username/password) to a message.
const msg = Buffer.alloc(512);
Rasapi32.RasGetErrorStringW(691, msg.ptr, 256);
console.log(new TextDecoder('utf-16le').decode(msg).replace(/\0.*$/, ''));

[!NOTE] AI agents: see AI.md for the package binding contract and source-navigation guidance. It explains how to use the package without scanning the entire implementation.

Examples

Run the included examples:

bun run example:dialup-screech    # Animated retro dial-up handshake visualizer
bun run example:ras-diagnostic    # Full RAS subsystem diagnostic report

Notes

• Either rely on lazy binding or call Rasapi32.Preload().
• Windows only. Bun runtime required.
• SAL types & naming: nullability is in the type — Optional<T> (formally optional, SAL _*opt_) and Nullable<T> (plain [in]/[out] the docs say can be NULL), the null sentinel derived from T (null for pointers LP*/P*, 0n for handles/by-value addresses); direction is in the parameter name — _out (_Out_), _in_out (_Inout_), _In_ bare. See AI.md and the repo AGENTS.md.