Websocket non-blocking server library

http://akinaru.github.io/websocket-non-blocking/

C++ websocket non-blocking server library for Qt4/Qt5

Usage

Start websocket server :

WebsocketServer server;

bool success = server.listen(QHostAddress("127.0.0.1"), 8443);

Stop websocket server :

server.close();

Integrate in your project

• from git submodule

git submodule add git://github.com/akinaru/websocket-non-blocking.git

and in your project.pro :

TEMPLATE = subdirs
SUBDIRS = websocket-non-blocking your-app
your-app.depends = websocket-non-blocking

with in your-app.pro :

TARGET = your-app
SOURCES = main.cpp
INCLUDEPATH += $$PWD/../websocket-non-blocking/libwebsocket/release
LIBS += -L$$PWD/../websocket-non-blocking/libwebsocket/release -lwebsocket
DEPENDPATH += $$PWD/../websocket-non-blocking/libwebsocket/release

Monitor clients

Build your own client monitoring class that inherits IClientEventListener :

class ClientSocketHandler :  public IClientEventListener
{
public:

    ClientSocketHandler();

    ~ClientSocketHandler();

    void onClientClose(IWebsocketClient &client);

    void onClientConnection(IWebsocketClient &client);

    void onMessageReceivedFromClient(IWebsocketClient &client, std::string message);
};

Add listener to server instance :

#include "ClientSockethandler.h"

....

ClientSocketHandler *clientHandler = new ClientSocketHandler();

server.addClientEventListener(clientHandler);

In this ClientSocketHandler you have 3 callbacks that will notify you on client connection change and arrival of client messages :

• void onClientClose(IWebsocketClient &client); notify when client socket close
• void onClientConnection(IWebsocketClient &client); notify when client socket connect to server
• void onMessageReceivedFromClient(IWebsocketClient &client,std::string message); notify when a socket client send a message to you

You can send a message back with IWebsocketClient sent from the same callback with sendMessage(std::string textToSend) method :

void ClientSocketHandler::onMessageReceivedFromClient(IWebsocketClient &client,string message)
{
    cout << "Client socket message received : " << message.data() << endl;

    client.sendMessage("OK I received your message !");
}

Check the client monitoring example here

SSL secured websocket server

WebsocketServer server;

server.setSSL(true); // set SSL to true (default is false)

Then you set your public/private/ca certificates separately with respective methods :

server.setPublicCert(SslHandler::retrieveCertFromFile(PUBLIC_CERT));
server.setPrivateCert(SslHandler::retrieveKeyCertFile(PRIVATE_CERT,PRIVATE_CERT_PASS));
server.setCaCert(SslHandler::retrieveveCaCertListFromFile(CA_CERTS));

You can use static method from SslHandler :

• public cert must be a QSslCertificate : SslHandler::retrieveCertFromFile(char * filepath)
• private cert must be a QSslKey : SslHandler::retrieveKeyCertFile(char * filepath,char * passKey)
• CA cert must be a QList of QSslCertificate : SslHandler::retrieveveCaCertListFromFile(char * filepath)

Eventually add event listener as described above and start websocket server :

server.addClientEventListener(clientHandler);

bool success = server.listen(QHostAddress("127.0.0.1"), 8443);

Troubleshooting SSL errors with local browser JS client

Bad certificate | Unknown CA errors

This could mean you didn't import your not-trusted-CA certificate into your browser.

The remote host closed the connection

Just load your URL with "https" : https://127.0.0.1:8443 . Browser will prompt you to accept the certificates and it will probably solve your connection error.

Debugging SSL connection error

use openssl command line tool to debug ssl connection :

openssl s_client -connect 127.0.0.1:8443

Server-Client key/cert generation

Sample certs are in libwesocket-test/certs folder, you will find server,client and ca cert build with easy-rsa :

https://github.com/OpenVPN/easy-rsa

With last release of easy-rsa, you can build your own key with the following :

• ./build-ca : generate a new CA for you
• ./build-server-full myServer : will build for you public cert and private cert signed with CA for server
• ./build-client-full myClient : will build for you public cert and private cert signed with CA for client

Build library & examples

qmake
make

Run examples

Open a websocket on port 8443 :

./libwebsocket-test/release/libwebsocket-test 127.0.0.1 8443

Open Javascript clients located in client-test/js :

---

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Valgrind checking

cd libwebsocket-test/release

valgrind --tool=memcheck --leak-check=full --suppressions=../../memcheck.suppress ./libwebsocket-test <ip> <port>

Compatibility

• Qt4
• Qt5

Specification

• https://tools.ietf.org/html/rfc6455