npm package: @inveniem/sftp-ws
Description: SFTP over WebSockets - client and server library
Author: Lukas Pokorny
Latest version: 0.8.1

@inveniem/sftp-ws
=================

SFTP over WebSockets - client and server library for Node.js.

## Overview
SFTP is a simple remote filesystem protocol misnamed as *SSH File Transfer 
Protocol*. This package provides SFTP v3, but layers it on top of WebSockets 
instead of SSH. This makes it possible to run an SFTP client in any modern web
browser.

Check out [Lukas's blogpost](https://lukas.pokorny.eu/sftp-over-websockets/) for
more information.

## Installing

To install from [npm](https://www.npmjs.com/package/@inveniem/sftp-ws):
```sh
npm install --save @inveniem/sftp-ws
```

Or use Yarn:
```shell
yarn add @inveniem/sftp-ws
```

## Using with Webpack in a Browser-based/SPA App
You will need to use the `@inveniem/sftp-ws-web` package instead of
`@inveniem/sftp-ws` package. In addition, this package is not yet 
RequireJS-compliant so you will need to use the WebPack exports loader to
provide a shim.

First, install `exports-loader` into your project with:

```sh
npm install --save --dev exports-loader
```

Or with Yarn:
```sh
yarn add --dev exports-loader
```

Then add this to your Webpack config (this is for Webpack v3):
```javascript
// ... lines omitted ...
module.exports = {
  // ... lines omitted ...
  module: {
    // ... lines omitted ...
    rules: [
      {
        test:     /\\\/sftp\\\.js$/,
        loader:   'exports-loader',
        options: {
          exports: {
            syntax: 'default',
            name:   'SFTP',
          },
        }
      },
      // ... lines omitted ...
    ]
  },
  // ... lines omitted ...
};
```

You can then `import` `SFTP` modules like you would any other dependency. For
example:
```jsx
import SFTP from '@inveniem/sftp-ws-web';

async function init() {
  const client = new SFTP.Client();
  let url = (window.location.protocol == "https") ? "wss" : "ws";
  url += "://" + window.location.hostname + ":" + window.location.port + "/sftp";

  try {
    await client.connect(url);
  }
  catch (err) {
    console.error("SFTP.WS error: " + err.message + " (" + err.type + ")");
  }
}
```

## Changes
### Version 0.8.1
This was a hotfix release to make the server package buildable on NodeJS v12 and
to make the web-only package suitable for use with a Webpack project that uses
RequireJS.

### Version 0.7
The API has been changed slightly in v0.7:
- SFTP client now features a dual Node.js-style and Promise-based API.
- IFilesystem API has been slightly modified. Arguments in `read` callback have
  been reversed, and `rename` method has been extended.

## API

The SFTP client provides a high-level API for multi-file operations, but it also 
aims to be compatible with SFTP client in
[ssh2 module](https://github.com/mscdex/ssh2) by Brian White.

Einaros [ws module](https://github.com/einaros/ws) is used to provide WebSockets
connectivity when used with NodeJS (not used in the web-browser-only package).

### Examples

Sample code is available in 
[this project's GitHub repository](https://github.com/inveniem/sftp-ws/tree/master/examples).

A stand-alone Browser-based SFTP/WS client is available as well. Check out the
[web client sample](https://github.com/inveniem/sftp-ws/tree/master/examples/web-client)
to see it in action.

### SFTP client - example (Node.js-style API):
```javascript
var SFTP = require('@inveniem/sftp-ws');

// url, credentials and options
var url = "ws://nuane.com/sftp";
var options = { username: "guest", password: "none" };

// connect to the server
var client = new SFTP.Client();
client.connect(url, options, function (err) {
    if (err) {
        // handle error
        console.log("Error: %s", err.message);
        return;
    }
    
    // display a message
    console.log("Connected to the server.");
    
    // retrieve directory listing
    client.list(".", function (err, list) {
        if (err) {
            // handle error
            console.log("Error: %s", err.message);
            return;
        }
        
        // display the listing
        list.forEach(function (item) {
            console.log(item.longname);
        });
        
        // disconnect
        client.end();
    });
});
```

### SFTP client - example (Promise-based API):
```javascript
var SFTP = require('@inveniem/sftp-ws');

// url, credentials and options
var url = "ws://nuane.com/sftp";
var options = {
    username: "guest",
    password: "none",
    promise: null // you can supply a custom Promise implementation
};

// connect to the server
var client = new SFTP.Client();
client.connect(url, options).then(function () {
    // display a message
    console.log("Connected to %s", url);
    
    // retrieve directory listing
    return client.list(".");

}).then(function (list) {
    // display the listing
    list.forEach(function (item) {
        console.log(item.longname);
    });

}).catch(function (err) {
    // handle errors
    console.log("Error: %s", err.message);

}).then(function () {
    // disconnect
    client.end();

});
```

### SFTP client - downloading files
```javascript

// initialize an SFTP client object here

// download all files matching the pattern
// (into the current local directory)
client.download('sftp-ws-*.tgz', '.');
```

### SFTP server - listening for connections:

```javascript
var SFTP = require('@inveniem/sftp-ws');

// start SFTP over WebSockets server
var server = new SFTP.Server({
    port: 3004,
    virtualRoot: '.',
    readOnly: true
});
```

## Virtual filesystems
This SFTP package is built around the `IFilesystem` interface:

```typescript
interface IFilesystem {
    open(path: string, flags: string, attrs: IStats, callback: (err: Error, handle: any) => any): void;
    close(handle: any, callback: (err: Error) => any): void;
    read(handle: any, buffer: Buffer, offset: number, length: number, position: number, callback: (err: Error, buffer: Buffer, bytesRead: number) => any): void;
    write(handle: any, buffer: Buffer, offset: number, length: number, position: number, callback: (err: Error) => any): void;
    lstat(path: string, callback: (err: Error, attrs: IStats) => any): void;
    fstat(handle: any, callback: (err: Error, attrs: IStats) => any): void;
    setstat(path: string, attrs: IStats, callback: (err: Error) => any): void;
    fsetstat(handle: any, attrs: IStats, callback: (err: Error) => any): void;
    opendir(path: string, callback: (err: Error, handle: any) => any): void;
    readdir(handle: any, callback: (err: Error, items: IItem[]|boolean) => any): void;
    unlink(path: string, callback: (err: Error) => any): void;
    mkdir(path: string, attrs: IStats, callback: (err: Error) => any): void;
    rmdir(path: string, callback: (err: Error) => any): void;
    realpath(path: string, callback: (err: Error, resolvedPath: string) => any): void;
    stat(path: string, callback: (err: Error, attrs: IStats) => any): void;
    rename(oldPath: string, newPath: string, flags: RenameFlags, callback: (err: Error) => any): void;
    readlink(path: string, callback: (err: Error, linkString: string) => any): void;
    symlink(oldPath: string, newPath: string, callback: (err: Error) => any): void;
    link(oldPath: string, newPath: string, callback: (err: Error) => any): void;
}

interface IStats {
    mode?: number;
    uid?: number;
    gid?: number;
    size?: number;
    atime?: Date;
    mtime?: Date;

    isFile? (): boolean;
    isDirectory? (): boolean;
    isSymbolicLink? (): boolean;
}

interface IItem {
    filename: string;
    stats: IStats;

    longname?: string;
    path?: string;
}

const enum RenameFlags {
    OVERWRITE = 1,
    //ATOMIC = 2,
    //NATIVE = 4,
}
```

- The functions of `IFilesystem` interface represent SFTP protocol commands and 
  resemble the `fs` module that comes with Node.js.
- The SFTP client object implements this interface (and other useful wrapper 
  methods).
- The SFTP server object makes instances of this interface accessible by 
  clients.

This package comes with an implementation of 'virtual filesystem' that uses `fs`
to make parts of the local filesystem accessible to SFTP clients. However, you
can easily implement a custom virtual filesystem and use it instead of the
built-in one - just supply an instance of `IFilesystem` to SFTP server's
constructor as `filesystem' option.

## Future
List of things I would like to add soon:
- More powerful API
- More unit tests
- Even more unit tests
- Better documentation
- SFTP/WS to SFTP/SSH proxy

## Contributors
- Guy Elsmore-Paddock at Inveniem