Add SSL Renegotiate handshake support to boost::asio::ssl

[georgid@…]

Currently the boost::asio::ssl::stream handshake can call either SSL_accept or SSL_connect for initial connection handshaking. To be able to do a SSL renegotiation handshake SSL_do_hanshake needs() to be called.

I have attached a patch that adds a new boost::asio::ssl::hanshake_type called "renegotiate" and the needed support in the ssl::engine to do a proper renegotiation handshake.

Doing a server side renegotiate to request the client certificate can be done in the following way:

#include <boost/asio.hpp>
#include <boost/asio/ssl.hpp>

typedef boost::asio::ssl::stream<boost::asio::ip::tcp::socket> ssl_socket;


int main(int argc, char* argv[])
{
   using namespace std; // For atoi.
   using namespace boost::asio;

   unsigned short port =  atoi(argv[1]);
   io_service io_service;

   ip::tcp::acceptor acceptor(io_service,
                              ip::tcp::endpoint(ip::tcp::v4(), port));

   ssl::context ctx(ssl::context::sslv23);
   ssl_socket sock(io_service, ctx);

   acceptor.accept(sock.lowest_layer());

   sock.handshake(ssl_socket::server);
   // read some data

   sock.set_verify_mode(ssl::verify_peer);
   sock.handshake(ssl_socket::renegotiate);
   
   // continue using the connection
}

[georgid@…]

Patch that adds support for SSL renegotiate handshake

[diptiburli21@…]

Hi Currently am using boost 1.58 , and want to be able to call SSL_renegotiate on native_handle(), In which case I need to call SSL_renegotiate and SSL_Handshake() explictly . Will that work if and boost async apis to read/write and initial handshake?