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//
// client.cpp
// ~~~~~~~~~~
//
// Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <boost/asio.hpp>
#include <boost/asio/ssl.hpp>
using boost::asio::ip::tcp;
using std::placeholders::_1;
using std::placeholders::_2;
enum { max_length = 1024 };
class client
{
public:
client(boost::asio::io_context& io_context,
boost::asio::ssl::context& context,
const tcp::resolver::results_type& endpoints)
: socket_(io_context, context)
{
socket_.set_verify_mode(boost::asio::ssl::verify_peer);
socket_.set_verify_callback(
std::bind(&client::verify_certificate, this, _1, _2));
connect(endpoints);
}
private:
bool verify_certificate(bool preverified,
boost::asio::ssl::verify_context& ctx)
{
// The verify callback can be used to check whether the certificate that is
// being presented is valid for the peer. For example, RFC 2818 describes
// the steps involved in doing this for HTTPS. Consult the OpenSSL
// documentation for more details. Note that the callback is called once
// for each certificate in the certificate chain, starting from the root
// certificate authority.
// In this example we will simply print the certificate's subject name.
char subject_name[256];
X509* cert = X509_STORE_CTX_get_current_cert(ctx.native_handle());
X509_NAME_oneline(X509_get_subject_name(cert), subject_name, 256);
std::cout << "Verifying " << subject_name << "\n";
return preverified;
}
void connect(const tcp::resolver::results_type& endpoints)
{
boost::asio::async_connect(socket_.lowest_layer(), endpoints,
[this](const boost::system::error_code& error,
const tcp::endpoint& /*endpoint*/)
{
if (!error)
{
handshake();
}
else
{
std::cout << "Connect failed: " << error.message() << "\n";
}
});
}
void handshake()
{
socket_.async_handshake(boost::asio::ssl::stream_base::client,
[this](const boost::system::error_code& error)
{
if (!error)
{
send_request();
}
else
{
std::cout << "Handshake failed: " << error.message() << "\n";
}
});
}
void send_request()
{
std::cout << "Enter message: ";
std::cin.getline(request_, max_length);
size_t request_length = std::strlen(request_);
boost::asio::async_write(socket_,
boost::asio::buffer(request_, request_length),
[this](const boost::system::error_code& error, std::size_t length)
{
if (!error)
{
receive_response(length);
}
else
{
std::cout << "Write failed: " << error.message() << "\n";
}
});
}
void receive_response(std::size_t length)
{
boost::asio::async_read(socket_,
boost::asio::buffer(reply_, length),
[this](const boost::system::error_code& error, std::size_t length)
{
if (!error)
{
std::cout << "Reply: ";
std::cout.write(reply_, length);
std::cout << "\n";
}
else
{
std::cout << "Read failed: " << error.message() << "\n";
}
});
}
boost::asio::ssl::stream<tcp::socket> socket_;
char request_[max_length];
char reply_[max_length];
};
int main(int argc, char* argv[])
{
try
{
if (argc != 3)
{
std::cerr << "Usage: client <host> <port>\n";
return 1;
}
boost::asio::io_context io_context;
tcp::resolver resolver(io_context);
auto endpoints = resolver.resolve(argv[1], argv[2]);
boost::asio::ssl::context ctx(boost::asio::ssl::context::sslv23);
ctx.load_verify_file("ca.pem");
client c(io_context, ctx, endpoints);
io_context.run();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
return 0;
}
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