C++ Socket library tutorial

Modify the StatusSocket server to use SSL

To enable SSL in a TcpSocket derived class only one method needs to be implemented. For a client class, the method is called InitSSLClient. For the server, it's called InitSSLServer. These methods does not take any input parameters. The client method needs to call InitializeContext with the ssl method that is to be used. The default implementation use SSLv23_method(), so it that's ok no InitSSLClient method needs to be implemented on your client class. The server method also needs to call InitializeContext, but with more parameters. The class need a combined key/certificate filename as first input parameter, and the password to the key as second. The third and final input parameter is again the ssl method to use.

To make a TcpSocket derived class use SSL, one must call EnableSSL(). This can be done in the class constructor if the class always should use ssl, or in the Init() method. Init() is called after a connection has been accepted, but before OnAccept().

The StatusSocket below will use Init(), and will only enable ssl if the incoming port number is 2222.

Create the server key and server certificate using openssl

Without going into any detail whatsoever, here are the steps needed to create a self-signed server certificate using openssl.

1. Create ca key

2. Create ca cert

3. Create server key

4. Create server certificate request

5. Sign server certificate

6. Copy server key and certificate to a combined file

(in windows command prompt:)

Now there is a server.pem file that the StatusSocket class can use to establish an ssl session.

Below follows the StatusSocket, modified for use in a SSL server.

#ifndef _STATUSSOCKET_H
#define _STATUSSOCKET_H

#include <TcpSocket.h>
#include <ISocketHandler.h>


class StatusSocket : public TcpSocket
{
public:
	StatusSocket(ISocketHandler& );

	void Init();

	void OnAccept();
	void InitSSLServer();
};


#endif // _STATUSSOCKET_H

#include <Utility.h>
#include "StatusSocket.h"


StatusSocket::StatusSocket(ISocketHandler& h)
:TcpSocket(h)
{
}


void StatusSocket::OnAccept()
{
	Send("Local hostname : " + Utility::GetLocalHostname() + "\n");
	Send("Local address : " + Utility::GetLocalAddress() + "\n");
	Send("Number of sockets in list : " + Utility::l2string(Handler().GetCount()) + "\n");
	Send("\n");
}


void StatusSocket::InitSSLServer()
{
	// here's the server.pem file we just created above
	// %! remember to change the password to the one you used for your server key
	InitializeContext("server.pem", "keypwd", SSLv23_method());
}


void StatusSocket::Init()
{
	if (GetParent() -> GetPort() == 2222)
	{
		EnableSSL();
	}
}