opendht/nodejs/README.md

# OpenDHT Node.js Bindings

Initial Node-API bindings using `node-addon-api` directly over the C++ library.
The package is private while its API and binary distribution are being developed.
Node.js 22.9 or later is required; the addon targets Node-API version 8.

## Build

Install the native dependencies described in [BUILD.md](../BUILD.md), plus Node.js,
a C++17 compiler, and CMake 3.21 or later. Ninja is optional.

```sh
cd nodejs
npm ci
npm run build
npm test
npm run typecheck
```

CMake.js builds OpenDHT from the parent source directory in `nodejs/build/native`.
It does not change the repository's existing build directory. Tools, Python,
peer discovery, documentation, and native tests default to disabled in this build.
Native CMake options can be passed through, for example:

```sh
npm run build -- --CDOPENDHT_PEER_DISCOVERY=ON
```

The loader checks local builds, then compatible Node-API binaries under `prebuilds/`.
Set `OPENDHT_NODE_BINDING` to an absolute addon path to select an explicit build.
Packaged binaries include OpenDHT and non-system native dependencies, so archive
installation does not require a compiler or a system OpenDHT installation.

## Example Tool

After building, start the TypeScript example from the repository root:

```sh
npm --prefix nodejs run dhtnode -- --port 4222 --bootstrap bootstrap.jami.net
```

The source is [examples/dhtnode.ts](examples/dhtnode.ts). `npm run build` compiles
it to JavaScript; run `npm run build:examples` after editing just the example.
Bootstrap is optional;
`--bootstrap-port` selects its UDP port. Use `--port 0` for a free local port.

```text
listen greeting
put greeting hello world
get greeting
sign greeting signed hello
cancel greeting
quit
```

Keys are text labels, hashed automatically; values are UTF-8 text. The tool
generates a fresh EC identity on each run and prints IPv4/IPv6 connectivity
changes. Operations run concurrently, leaving the prompt responsive; dependent
commands should be entered after their preceding operation completes. EOF waits
for pending operations, then cancels listeners and closes the runner. Ctrl-C,
SIGTERM, and `quit` close immediately, rejecting pending operations without
printing cancellation errors. `--help` lists all options. Archives include both
the TypeScript source and compiled `examples/dhtnode.js`, runnable without
TypeScript or development dependencies, including from inside `node_modules`.

## Usage

```js
import { DhtRunner, hash } from './nodejs/index.js';

async function main() {
    const writer = new DhtRunner();
    const reader = new DhtRunner();
    try {
        writer.run({ port: 0, ipv4: '127.0.0.1', ipv6: '::1' });
        reader.run({ port: 0, ipv4: '127.0.0.1', ipv6: '::1' });
        writer.bootstrap('127.0.0.1', reader.getBoundPort());
        reader.bootstrap('127.0.0.1', writer.getBoundPort());
        const key = hash('example');
        const stored = await writer.put(key, Buffer.from('hello'), { id: 42n });
        if (!stored) throw new Error('DHT put failed');
        for (const value of await reader.get(key)) {
            console.log(value.id, value.data.toString());
        }
    } finally {
        await Promise.all([writer.close(), reader.close()]);
    }
}

main().catch(console.error);
```

## API

- `hash(string | Uint8Array)` returns a SHA-1 hash as a 40-character hex string.
  All get/put/listen keys must be hex hashes, not unhashed application keys.
- `version` is the underlying OpenDHT version.
- `run({port, ipv4, ipv6, network, persistPath, identity})` starts a threaded node. Port 0
  selects a free port. The defaults bind both IP families on all interfaces.
  `persistPath` is optional; use an empty string to disable persistence.
- `getBoundPort(4 | 6)` defaults to IPv4; `getNodeId()` returns the node's hex ID.
- `getStatus()` returns the latest JS-dispatched `{ipv4, ipv6}` connectivity
  snapshot. Each family is `'disconnected'`, `'connecting'`, or `'connected'`.
  `runner.on('statusChanged', status => {})` receives changes on the JS thread.
  New and closing/closed runners report both families as disconnected. No status
  events are delivered after close begins; close does not emit a final event.
- `bootstrap(host, port)` queues bootstrap discovery. Returning does not mean the
  peer is connected; subsequent DHT operations report their own completion.
- `put(key, Uint8Array, {id, type, userType, permanent})` copies the input and
  resolves to the native success boolean. IDs are unsigned 64-bit `bigint` values.
- `get(key)` resolves to value snapshots, or rejects with `ERR_DHT_GET_FAILED`.
  Values contain `id`, `type`, `seq`, `userType`, copied `Buffer` data, `isSigned`,
  `isEncrypted`, and an `owner` long fingerprint (or null for unsigned values).
- `listen(key, (value, expired) => {})` returns a listener with idempotent
  `cancel()`. Queued deliveries are suppressed after cancellation. Callback
  return values are ignored; callbacks may cancel or close the runner.
- `close()` is idempotent and returns the same promise on repeated calls. It
  waits off the JS thread for graceful shutdown, then joins the native threads.
  After two seconds it forces the join if graceful shutdown has not completed.
  Pending operations reject with `ERR_DHT_CLOSED`. A closed runner cannot restart.
- `ref()` and `unref()` control whether the runner keeps Node's event loop alive.
  Running nodes are referenced by default. `Symbol.asyncDispose` calls `close()`.

Callbacks run only on their owning JS thread. There is no polling timer or worker
thread waiting on each get/put. Explicitly close runners; GC cleanup and Node
environment cleanup hooks are fallbacks, including forced worker termination.
Pending operations, active listeners, and registered error/status handlers keep their
runner alive until completion, cancellation, handler removal, or explicit close.
Graceful persistence cannot be guaranteed if the process is killed.

The cross-thread queue is limited to 1,024 events and 16 MiB, and each accumulated
get result is limited to 16 MiB and 65,536 values. Exceeding a limit closes the
runner, emits an `error` event with code `ERR_DHT_OVERFLOW`, and rejects pending
operations and `close()`. Install an `error` handler on long-lived runners. As
with other Node EventEmitters, an unhandled `error` event is fatal. There is no
silent dropping of events while continuing an apparently healthy listener.

## Crypto

`PrivateKey.generate(options)` and `Identity.generate(name, options)` return
promises and generate keys off the JS thread. Options accept `algorithm: 'ec'`
(the default, using OpenDHT's default EC curve) or `'rsa'`. RSA `bits` must be an
integer between 2048 and 8192; the default is 2048.

- `new PrivateKey(bytes, password?)` imports PEM/DER; `serialize(password?)`
  exports PKCS#8 PEM. A nonempty password encrypts the exported key.
- `privateKey.getPublicKey()` returns an owned public key. `sign(bytes)` and
  `decrypt(bytes)` return copied Buffers.
- `new PublicKey(bytes)` imports a public key; `serialize()` exports DER.
  `checkSignature(data, signature)` returns a boolean. `encrypt(bytes)` requires
  an RSA key; EC keys support signatures, not this encryption scheme.
- `new Certificate(bytes)` imports PEM/DER or a PEM certificate chain;
  `serialize()` exports a PEM chain. Import does not establish trust or validate
  the chain against a trust store. `getPublicKey()` returns its public key.
- Public keys and certificates expose `getId()` (40 hex characters) and
  `getLongId()` (64 hex characters).
- `new Identity(privateKey, certificate)` requires matching fingerprints.
  Its read-only `privateKey` and `certificate` properties return owned wrappers.
- Pass `identity` to `run()` to enable `putSigned(key, data, options?)` and
  `putEncrypted(key, data, recipientPublicKey, options?)`. Both return the same
  success boolean as `put()`. Encrypted values are signed by the sender and
  transparently decrypted for the recipient by OpenDHT's get/listen layer.

```js
import { Identity, DhtRunner } from './nodejs/index.js';

async function createAuthenticatedNode() {
    const identity = await Identity.generate('example', { algorithm: 'rsa', bits: 2048 });
    const runner = new DhtRunner();
    runner.run({ port: 0, identity });
    return { runner, identity };
}
```

Crypto methods take Uint8Array/Buffer inputs, not implicit text encodings. Imports
must be nonempty and crypto inputs are limited to 16 MiB. Malformed handles/data,
mismatched identities, and unsupported encryption keys raise JS exceptions.
Only generation is asynchronous; import/export/sign/encrypt/decrypt are
synchronous and should be used from worker threads for large workloads.

## Packaging And CI

From a successful Release build:

```sh
npm run package
npm run test:package
```

`bundle` copies the addon into `prebuilds/<platform>-<arch>/`, gathers its runtime
dependencies, rewrites native loader paths, and copies dependency license
notices. macOS needs `dylibbundler` and Apple developer tools; Linux needs
`patchelf` and Debian/Ubuntu dependency copyright files. Windows uses the vcpkg
installed tree (`VCPKG_INSTALLED_DIR`, `VCPKG_DEFAULT_TRIPLET`) and MSVC tools.
`OPENDHT_LIBRARY_PATH` adds native library search directories when bundling.
An explicit addon path may be passed to `npm run bundle -- /absolute/addon.node`.
Bundling replaces only the current platform's generated prebuild directory.

`test:package` creates an npm archive, installs it in a temporary consumer with
install scripts disabled and no dev dependencies, forces prebuild-only loading,
and runs the full runtime suite. Pass an archive file or a directory containing
one archive to test it directly, for example `npm run test:package -- dist`.
Only runtime JS, declarations, the example's TypeScript source, documentation,
and prebuilds are included in the archive. `prepack` compiles the example, so
archive creation needs the development dependencies; archive installation does not.

The [Node.js package workflow](../.github/workflows/nodejs-package.yml) builds:

| Target | Build Baseline |
| --- | --- |
| Linux x64 | Ubuntu 24.04 / glibc 2.39 (Noble dependency image) |
| macOS ARM64 and x64 | macOS 15 |
| Windows x64 | Windows Server 2022 / MSVC |

The Linux build uses `ghcr.io/savoirfairelinux/opendht/opendht-deps-noble`,
built from [the Noble Dockerfile](../docker/DockerfileDepsNoble), restored from
the Ubuntu 24.04 recipe in git history. The release workflow publishes this
multi-architecture image alongside the other Docker images. Node builds use its
published `latest` tag. simdutf is linked statically because Ubuntu 24.04 does not
provide its development package.

CI combines platform prebuilds into one npm archive and verifies that archive on
Node 22, 24, and 26 on each platform, including Ubuntu 24.04 and 26.04. Published
GitHub releases receive the verified archive only after all install tests pass.
The package remains private;
the workflow does not publish to the npm registry or require an npm token.
musl/Alpine and other architectures are not currently built. Node-API stability
does not remove OS/libc or native dependency compatibility requirements. Review
the included dependency licenses and source-distribution obligations before
redistributing binaries beyond these development/release artifacts.

Query filters, async iterators, AbortSignal support, certificate trust-store
validation, CA issuance controls, and proxy controls remain future work.