tls.hpp

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/*
 * Copyright (c) 2015, Peter Thorson. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the WebSocket++ Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL PETER THORSON BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef WEBSOCKETPP_TRANSPORT_SECURITY_TLS_HPP
#define WEBSOCKETPP_TRANSPORT_SECURITY_TLS_HPP

#include <websocketpp/transport/asio/security/base.hpp>

#include <websocketpp/uri.hpp>

#include <websocketpp/common/asio_ssl.hpp>
#include <websocketpp/common/asio.hpp>
#include <websocketpp/common/connection_hdl.hpp>
#include <websocketpp/common/functional.hpp>
#include <websocketpp/common/memory.hpp>

#include <sstream>
#include <string>

namespace websocketpp {
namespace transport {
namespace asio {
namespace tls_socket {

typedef lib::function<void(connection_hdl,lib::asio::ssl::stream<
    lib::asio::ip::tcp::socket>&)> socket_init_handler;
typedef lib::function<lib::shared_ptr<lib::asio::ssl::context>(connection_hdl)>
    tls_init_handler;


class connection : public lib::enable_shared_from_this<connection> {
public:
    typedef connection type;
    typedef lib::shared_ptr<type> ptr;

    typedef lib::asio::ssl::stream<lib::asio::ip::tcp::socket> socket_type;
    typedef lib::shared_ptr<socket_type> socket_ptr;
    typedef lib::asio::io_service * io_service_ptr;
    typedef lib::shared_ptr<lib::asio::io_service::strand> strand_ptr;
    typedef lib::shared_ptr<lib::asio::ssl::context> context_ptr;

    explicit connection() {
        //std::cout << "transport::asio::tls_socket::connection constructor"
        //          << std::endl;
    }

    ptr get_shared() {
        return shared_from_this();
    }


    bool is_secure() const {
        return true;
    }


    socket_type::lowest_layer_type & get_raw_socket() {
        return m_socket->lowest_layer();
    }


    socket_type::next_layer_type & get_next_layer() {
        return m_socket->next_layer();
    }


    socket_type & get_socket() {
        return *m_socket;
    }


    void set_socket_init_handler(socket_init_handler h) {
        m_socket_init_handler = h;
    }


    void set_tls_init_handler(tls_init_handler h) {
        m_tls_init_handler = h;
    }


    std::string get_remote_endpoint(lib::error_code & ec) const {
        std::stringstream s;

        lib::asio::error_code aec;
        lib::asio::ip::tcp::endpoint ep = m_socket->lowest_layer().remote_endpoint(aec);

        if (aec) {
            ec = error::make_error_code(error::pass_through);
            s << "Error getting remote endpoint: " << aec
               << " (" << aec.message() << ")";
            return s.str();
        } else {
            ec = lib::error_code();
            s << ep;
            return s.str();
        }
    }
protected:

    lib::error_code init_asio (io_service_ptr service, strand_ptr strand,
        bool is_server)
    {
        if (!m_tls_init_handler) {
            return socket::make_error_code(socket::error::missing_tls_init_handler);
        }
        m_context = m_tls_init_handler(m_hdl);

        if (!m_context) {
            return socket::make_error_code(socket::error::invalid_tls_context);
        }
        m_socket = lib::make_shared<socket_type>(
            _WEBSOCKETPP_REF(*service),lib::ref(*m_context));

        m_io_service = service;
        m_strand = strand;
        m_is_server = is_server;

        return lib::error_code();
    }


    void set_uri(uri_ptr u) {
        m_uri = u;
    }


    void pre_init(init_handler callback) {
        // TODO: is this the best way to check whether this function is 
        //       available in the version of OpenSSL being used?
        // TODO: consider case where host is an IP address
#if OPENSSL_VERSION_NUMBER >= 0x90812f
        if (!m_is_server) {
            // For clients on systems with a suitable OpenSSL version, set the
            // TLS SNI hostname header so connecting to TLS servers using SNI
            // will work.
            long res = SSL_set_tlsext_host_name(
                get_socket().native_handle(), m_uri->get_host().c_str());
            if (!(1 == res)) {
                callback(socket::make_error_code(socket::error::tls_failed_sni_hostname));
            }
        }
#endif

        if (m_socket_init_handler) {
            m_socket_init_handler(m_hdl,get_socket());
        }

        callback(lib::error_code());
    }


    void post_init(init_handler callback) {
        m_ec = socket::make_error_code(socket::error::tls_handshake_timeout);

        // TLS handshake
        if (m_strand) {
            m_socket->async_handshake(
                get_handshake_type(),
                m_strand->wrap(lib::bind(
                    &type::handle_init, get_shared(),
                    callback,
                    lib::placeholders::_1
                ))
            );
        } else {
            m_socket->async_handshake(
                get_handshake_type(),
                lib::bind(
                    &type::handle_init, get_shared(),
                    callback,
                    lib::placeholders::_1
                )
            );
        }
    }


    void set_handle(connection_hdl hdl) {
        m_hdl = hdl;
    }

    void handle_init(init_handler callback,lib::asio::error_code const & ec) {
        if (ec) {
            m_ec = socket::make_error_code(socket::error::tls_handshake_failed);
        } else {
            m_ec = lib::error_code();
        }

        callback(m_ec);
    }

    lib::error_code get_ec() const {
        return m_ec;
    }


    lib::asio::error_code cancel_socket() {
        lib::asio::error_code ec;
        get_raw_socket().cancel(ec);
        return ec;
    }

    void async_shutdown(socket::shutdown_handler callback) {
        if (m_strand) {
            m_socket->async_shutdown(m_strand->wrap(callback));
        } else {
            m_socket->async_shutdown(callback);
        }
    }


    template <typename ErrorCodeType>
    lib::error_code translate_ec(ErrorCodeType ec) {
        if (ec.category() == lib::asio::error::get_ssl_category()) {
            if (ERR_GET_REASON(ec.value()) == SSL_R_SHORT_READ) {
                return make_error_code(transport::error::tls_short_read);
            } else {
                // We know it is a TLS related error, but otherwise don't know
                // more. Pass through as TLS generic.
                return make_error_code(transport::error::tls_error);
            }
        } else {
            // We don't know any more information about this error so pass
            // through
            return make_error_code(transport::error::pass_through);
        }
    }
    
    lib::error_code translate_ec(lib::error_code ec) {
        // Normalize the tls_short_read error as it is used by the library and 
        // needs a consistent value. All other errors pass through natively.
        // TODO: how to get the SSL category from std::error?
        /*if (ec.category() == lib::asio::error::get_ssl_category()) {
            if (ERR_GET_REASON(ec.value()) == SSL_R_SHORT_READ) {
                return make_error_code(transport::error::tls_short_read);
            }
        }*/
        return ec;
    }
private:
    socket_type::handshake_type get_handshake_type() {
        if (m_is_server) {
            return lib::asio::ssl::stream_base::server;
        } else {
            return lib::asio::ssl::stream_base::client;
        }
    }

    io_service_ptr      m_io_service;
    strand_ptr          m_strand;
    context_ptr         m_context;
    socket_ptr          m_socket;
    uri_ptr             m_uri;
    bool                m_is_server;

    lib::error_code     m_ec;

    connection_hdl      m_hdl;
    socket_init_handler m_socket_init_handler;
    tls_init_handler    m_tls_init_handler;
};


class endpoint {
public:
    typedef endpoint type;

    typedef connection socket_con_type;
    typedef socket_con_type::ptr socket_con_ptr;

    explicit endpoint() {}


    bool is_secure() const {
        return true;
    }


    void set_socket_init_handler(socket_init_handler h) {
        m_socket_init_handler = h;
    }


    void set_tls_init_handler(tls_init_handler h) {
        m_tls_init_handler = h;
    }
protected:

    lib::error_code init(socket_con_ptr scon) {
        scon->set_socket_init_handler(m_socket_init_handler);
        scon->set_tls_init_handler(m_tls_init_handler);
        return lib::error_code();
    }

private:
    socket_init_handler m_socket_init_handler;
    tls_init_handler m_tls_init_handler;
};

} // namespace tls_socket
} // namespace asio
} // namespace transport
} // namespace websocketpp

#endif // WEBSOCKETPP_TRANSPORT_SECURITY_TLS_HPP