# http2-wrapper
> HTTP/2 client, just with the familiar `https` API
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This package was created to support HTTP/2 without the need to rewrite your code.
I recommend adapting to the [`http2`](https://nodejs.org/api/http2.html) module if possible - it's much simpler to use and has many cool features!
**Tip**: `http2-wrapper` is very useful when you rely on other modules that use the HTTP/1 API and you want to support HTTP/2.
**Pro Tip**: While the native `http2` doesn't have agents yet, you can use `http2-wrapper` Agents and still operate on the native HTTP/2 streams.
## Installation
> `$ npm install http2-wrapper`
> `$ yarn add http2-wrapper`
## Usage
```js
const http2 = require('http2-wrapper');
const options = {
hostname: 'nghttp2.org',
protocol: 'https:',
path: '/httpbin/post',
method: 'POST',
headers: {
'content-length': 6
}
};
const request = http2.request(options, response => {
console.log('statusCode:', response.statusCode);
console.log('headers:', response.headers);
const body = [];
response.on('data', chunk => {
body.push(chunk);
});
response.on('end', () => {
console.log('body:', Buffer.concat(body).toString());
});
});
request.on('error', console.error);
request.write('123');
request.end('456');
// statusCode: 200
// headers: [Object: null prototype] {
// ':status': 200,
// date: 'Fri, 27 Sep 2019 19:45:46 GMT',
// 'content-type': 'application/json',
// 'access-control-allow-origin': '*',
// 'access-control-allow-credentials': 'true',
// 'content-length': '239',
// 'x-backend-header-rtt': '0.002516',
// 'strict-transport-security': 'max-age=31536000',
// server: 'nghttpx',
// via: '1.1 nghttpx',
// 'alt-svc': 'h3-23=":4433"; ma=3600',
// 'x-frame-options': 'SAMEORIGIN',
// 'x-xss-protection': '1; mode=block',
// 'x-content-type-options': 'nosniff'
// }
// body: {
// "args": {},
// "data": "123456",
// "files": {},
// "form": {},
// "headers": {
// "Content-Length": "6",
// "Host": "nghttp2.org"
// },
// "json": 123456,
// "origin": "xxx.xxx.xxx.xxx",
// "url": "https://nghttp2.org/httpbin/post"
// }
```
## API
**Note:** The `session` option was renamed to `tlsSession` for better readability.
**Note:** The `timeout` option applies to HTTP/2 streams only. In order to set session timeout, pass an Agent with custom `timeout` option set.
### http2.auto(url, options, callback)
Performs [ALPN](https://nodejs.org/api/tls.html#tls_alpn_and_sni) negotiation.
Returns a Promise giving proper `ClientRequest` instance (depending on the ALPN).
**Note**: The `agent` option represents an object with `http`, `https` and `http2` properties.
```js
const http2 = require('http2-wrapper');
const options = {
hostname: 'httpbin.org',
protocol: 'http:', // Try changing this to https:
path: '/post',
method: 'POST',
headers: {
'content-length': 6
}
};
(async () => {
try {
const request = await http2.auto(options, response => {
console.log('statusCode:', response.statusCode);
console.log('headers:', response.headers);
const body = [];
response.on('data', chunk => body.push(chunk));
response.on('end', () => {
console.log('body:', Buffer.concat(body).toString());
});
});
request.on('error', console.error);
request.write('123');
request.end('456');
} catch (error) {
console.error(error);
}
})();
// statusCode: 200
// headers: { connection: 'close',
// server: 'gunicorn/19.9.0',
// date: 'Sat, 15 Dec 2018 18:19:32 GMT',
// 'content-type': 'application/json',
// 'content-length': '259',
// 'access-control-allow-origin': '*',
// 'access-control-allow-credentials': 'true',
// via: '1.1 vegur' }
// body: {
// "args": {},
// "data": "123456",
// "files": {},
// "form": {},
// "headers": {
// "Connection": "close",
// "Content-Length": "6",
// "Host": "httpbin.org"
// },
// "json": 123456,
// "origin": "xxx.xxx.xxx.xxx",
// "url": "http://httpbin.org/post"
// }
```
### http2.auto.protocolCache
An instance of [`quick-lru`](https://github.com/sindresorhus/quick-lru) used for ALPN cache.
There is a maximum of 100 entries. You can modify the limit through `protocolCache.maxSize` - note that the change will be visible globally.
### http2.auto.createResolveProtocol(cache, queue, connect)
#### cache
Type: `Map`
This is the store where cached ALPN protocols are put into.
#### queue
Type: `Map`
This is the store that contains pending ALPN negotiation promises.
#### connect
Type: `(options, callback) => TLSSocket | Promise`
See https://github.com/szmarczak/resolve-alpn#connect
### http2.auto.resolveProtocol(options)
Returns a `Promise<{alpnProtocol: string}>`.
### http2.request(url, options, callback)
Same as [`https.request`](https://nodejs.org/api/https.html#https_https_request_options_callback).
##### options.h2session
Type: `Http2Session`
The session used to make the actual request. If none provided, it will use `options.agent` to get one.
### http2.get(url, options, callback)
Same as [`https.get`](https://nodejs.org/api/https.html#https_https_get_options_callback).
### new http2.ClientRequest(url, options, callback)
Same as [`https.ClientRequest`](https://nodejs.org/api/https.html#https_class_https_clientrequest).
### new http2.IncomingMessage(socket)
Same as [`https.IncomingMessage`](https://nodejs.org/api/https.html#https_class_https_incomingmessage).
### new http2.Agent(options)
**Note:** this is **not** compatible with the classic `http.Agent`.
Usage example:
```js
const http2 = require('http2-wrapper');
class MyAgent extends http2.Agent {
createConnection(origin, options) {
console.log(`Connecting to ${http2.Agent.normalizeOrigin(origin)}`);
return http2.Agent.connect(origin, options);
}
}
http2.get({
hostname: 'google.com',
agent: new MyAgent()
}, response => {
response.on('data', chunk => console.log(`Received chunk of ${chunk.length} bytes`));
});
```
#### options
Each option is an `Agent` property and can be changed later.
##### timeout
Type: `number`
Default: `0`
If there's no activity after `timeout` milliseconds, the session will be closed. If `0`, no timeout is applied.
##### maxSessions
Type: `number`
Default: `Infinity`
The maximum amount of sessions in total.
##### maxEmptySessions
Type: `number`
Default: `10`
The maximum amount of empty sessions in total. An empty session is a session with no pending requests.
##### maxCachedTlsSessions
Type: `number`
Default: `100`
The maximum amount of cached TLS sessions.
#### agent.protocol
Type: `string`
Default: `https:`
#### agent.settings
Type: `object`
Default: `{enablePush: false}`
[Settings](https://nodejs.org/api/http2.html#http2_settings_object) used by the current agent instance.
#### agent.normalizeOptions([options](https://github.com/szmarczak/http2-wrapper/blob/master/source/agent.js))
Returns a string representing normalized options.
```js
Agent.normalizeOptions({servername: 'example.com'});
// => ':::::::::::::::::::::::::::::::::::::'
```
#### agent.getSession(origin, options)
##### [origin](https://nodejs.org/api/http2.html#http2_http2_connect_authority_options_listener)
Type: `string` `URL` `object`
Origin used to create new session.
##### [options](https://nodejs.org/api/http2.html#http2_http2_connect_authority_options_listener)
Type: `object`
Options used to create new session.
Returns a Promise giving free `Http2Session`. If no free sessions are found, a new one is created.
A session is considered free when pending streams count is less than max concurrent streams settings.
#### agent.getSession([origin](#origin), [options](options-1), listener)
##### listener
Type: `object`
```
{
reject: error => void,
resolve: session => void
}
```
If the `listener` argument is present, the Promise will resolve immediately. It will use the `resolve` function to pass the session.
#### agent.request([origin](#origin), [options](#options-1), [headers](https://nodejs.org/api/http2.html#http2_headers_object), [streamOptions](https://nodejs.org/api/http2.html#http2_clienthttp2session_request_headers_options))
Returns a Promise giving `Http2Stream`.
#### agent.createConnection([origin](#origin), [options](#options-1))
Returns a new `TLSSocket`. It defaults to `Agent.connect(origin, options)`.
#### agent.closeEmptySessions(count)
##### count
Type: `number`
Default: `Number.POSITIVE_INFINITY`
Makes an attempt to close empty sessions. Only sessions with 0 concurrent streams will be closed.
#### agent.destroy(reason)
Destroys **all** sessions.
#### agent.emptySessionCount
Type: `number`
A number of empty sessions.
#### agent.pendingSessionCount
Type: `number`
A number of pending sessions.
#### agent.sessionCount
Type: `number`
A number of all sessions held by the Agent.
#### Event: 'session'
```js
agent.on('session', session => {
// A new session has been created by the Agent.
});
```
## Proxy support
Currently `http2-wrapper` provides support for these proxies:
- `HttpOverHttp2`
- `HttpsOverHttp2`
- `Http2OverHttp2`
- `Http2OverHttp`
- `Http2OverHttps`
Any of the above can be accessed via `http2wrapper.proxies`. Check out the [`examples/proxies`](examples/proxies) directory to learn more.
**Note:** If you use the `http2.auto` function, the real IP address will leak. `http2wrapper` is not aware of the context. It will create a connection to the end server using your real IP address to get the ALPN protocol. Then it will create another connection using proxy. To migitate this, you need to pass a custom `resolveProtocol` function as an option:
```js
const resolveAlpnProxy = new URL('https://username:password@localhost:8000');
const connect = async (options, callback) => new Promise((resolve, reject) => {
const host = `${options.host}:${options.port}`;
(async () => {
try {
const request = await http2.auto(resolveAlpnProxy, {
method: 'CONNECT',
headers: {
host
},
path: host,
// For demo purposes only!
rejectUnauthorized: false,
});
request.end();
request.once('error', reject);
request.once('connect', (response, socket, head) => {
if (head.length > 0) {
reject(new Error(`Unexpected data before CONNECT tunnel: ${head.length} bytes`));
socket.destroy();
return;
}
const tlsSocket = tls.connect({
...options,
socket
}, callback);
resolve(tlsSocket);
});
} catch (error) {
reject(error);
}
})();
});
// This is required to prevent leaking real IP address on ALPN negotiation
const resolveProtocol = http2.auto.createResolveProtocol(new Map(), new Map(), connect);
const request = await http2.auto('https://httpbin.org/anything', {
agent: {…},
resolveProtocol
}, response => {
// Read the response here
});
request.end();
```
See [`unknown-over-unknown.js`](examples/proxies/unknown-over-unknown.js) to learn more.
## Mirroring another server
See [`examples/proxies/mirror.js`](examples/proxies/mirror.js) for an example.
## [WebSockets over HTTP/2](https://tools.ietf.org/html/rfc8441)
See [`examples/ws`](examples/ws) for an example.
## Push streams
See [`examples/push-stream`](examples/push-stream) for an example.
## Related
- [`got`](https://github.com/sindresorhus/got) - Simplified HTTP requests
- [`http2-proxy`](https://github.com/nxtedition/node-http2-proxy) - A simple http/2 & http/1.1 spec compliant proxy helper for Node.
## License
MIT