Google Summer of code 2016 - WebSocket for syslog ng

It’s my honor to get the chance to take part in GSoC 2016. Almost everything is ready now. Here is my proposal. You can view my pull request

Deliverables

• A new WebSocket destination
  • It is stable and can run steadily. All kinds of exception, such as disconnection , can be handled properly.
  • It supports secure connection, server mode, client mode.
  • It is configurable and can meet most of the requirements of users to send log messages to a WebSocket Server.
• A sample WebSocket server to communicate with the WebSocket destination to prove that it is working properly.
• A sample web browser WebSocket client to show how to subscribe log message from the WebSocket destination.
• A new WebSocket source.
  • It supports secure connection
  • It is stable and can run steadily. All kinds of exception, such as disconnection , can be handled properly.
  • It is configurable.
• The code style should be good. Python code will follow most of the conventions defined in PEP8. C code will follow the GNU Coding Standards
• README files that can be easily understood by normal users.

Websocket source and destination

Introduction

The Websocket destination can send log messages to an WebSocket Server directly. In addition, this destination can also act as a WebSocket server, so the WebSocket client (such as a javascript client in a browser) could subscribe directly to it to get log messages. These will make sending log message privately or publicly much easier. A WebSocket source is also included. It can receive log messages directly from WebSocket clients.

Installation

If you want to compile syslog-ng-incubator with the websocket source and destination, you must have libwebsockets installed in your system.

Please go to libwebsockets official website to download v2.0-stable and install it.

Test helper scripts

There is some scripts which can help you test the module easier. Please refer to README

Configuration

Here is an example of an destination example which act as a client

@version: 3.7
@include "scl.conf"

source      s_system { system(); internal();};

destination ws_client_des {
    websocket(
        mode("client")
        protocol("example-protocol")
        address("127.0.0.1")
        path("/")
        port(8000)
        template("$HOST $ISODATE $MSG")
        ssl(
            allow_self_signed
            cert("/root/tmp/keys/server.crt")
            key("/root/tmp/keys/server.key")
        )
    );
};

log { source(s_system); destination(ws_client_des); };

Options explanation

This section will explain the options

mode: The mode of the destination. Only server mode and client mode are supported

protocol: websocket protocol

address: websocket server listening address

port: websocket server listening port

path: the path of the websocket server service

ssl: If this config appears, ssl will be used.

allow_self_signed: If you want to allow self-signed certificate when ssl is enabled, plese use this configue.

cert: When it act as an websocket client it is optional. If the server wants us to present a valid SSL client, certificate, you can the filepath of it

key: the private key for the cert

cacert (optional) When it act as an client, it is a CA cert and CRL can be used to validate the cert send by the server.

The websocket apis and examples

I write a api wrapper for libwebsockets, so using libwebsockets will be much easier.

More detailed description can be found in the README.