.. _examples_accept:

examples/accept.cpp
#####################

Accept connections from Bitcoin nodes on port 8333.

::

    #include <bitcoin/bitcoin.hpp>
    using namespace bc;
    
    using std::placeholders::_1;
    using std::placeholders::_2;
    
    // Listening has started.
    // Wait to accept a connection.
    void listening_started(const std::error_code& ec, acceptor_ptr accept);
    // Connection to another Bitcoin node has been established.
    // Wait for version message.
    void accepted_connection(const std::error_code& ec, channel_ptr node,
        acceptor_ptr accept);
    // Version message received.
    // Display the user agent.
    void version_received(const std::error_code& ec, const version_type& version,
        channel_ptr node);
    void node_stopped(const std::error_code& ec);
    
    void listening_started(const std::error_code& ec, acceptor_ptr accept)
    {
        if (ec)
        {
            log_error() << "Listen: " << ec.message();
            return;
        }
        // Accept first connection.
        accept->accept(
            std::bind(accepted_connection, _1, _2, accept));
    }
    
    void accepted_connection(const std::error_code& ec, channel_ptr node,
        acceptor_ptr accept)
    {
        if (ec)
        {
            log_error() << "Accept: " << ec.message();
            return;
        }
        log_info() << "Accepted connection!";
        node->subscribe_stop(node_stopped);
        // Now we need to keep it alive otherwise the connection is closed.
        node->subscribe_version(
            std::bind(version_received, _1, _2, node));
        // Keep accepting more connections.
        accept->accept(
            std::bind(accepted_connection, _1, _2, accept));
    }
    
    void version_received(const std::error_code& ec, const version_type& version,
        channel_ptr node)
    {
        // error::service_stopped means the connection was closed.
        if (ec == error::service_stopped)
            return;
        else if (ec)
        {
            log_error() << "Version message: " << ec.message();
            return;
        }
        log_info() << "User agent: " << version.user_agent;
    }
    
    void node_stopped(const std::error_code& ec)
    {
        if (ec == error::service_stopped)
            log_info() << "Connection closed.";
        else if (ec)
            log_error() << "Connection closed: " << ec.message();
    }
    
    int main()
    {
        threadpool pool(4);
        network net(pool);
        net.listen(8333, listening_started);
        std::cin.get();
        pool.stop();
        pool.join();
        return 0;
    }

