//
// client.cpp
// ~~~~~~~~~~
//
// Copyright (c) 2003-2025 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;
}