multiplayer.cpp

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/*
   Copyright (C) 2007 - 2018 by David White <dave@whitevine.net>
   Part of the Battle for Wesnoth Project https://www.wesnoth.org

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details.
*/

#include "game_initialization/multiplayer.hpp"

#include "addon/manager.hpp" // for installed_addons
#include "events.hpp"
#include "formula/string_utils.hpp"
#include "game_config_manager.hpp"
#include "game_initialization/mp_game_utils.hpp"
#include "game_initialization/playcampaign.hpp"
#include "preferences/credentials.hpp"
#include "preferences/game.hpp"
#include "gettext.hpp"
#include "gui/dialogs/loading_screen.hpp"
#include "gui/dialogs/message.hpp"
#include "gui/dialogs/multiplayer/lobby.hpp"
#include "gui/dialogs/multiplayer/mp_create_game.hpp"
#include "gui/dialogs/multiplayer/mp_join_game.hpp"
#include "gui/dialogs/multiplayer/mp_login.hpp"
#include "gui/dialogs/multiplayer/mp_staging.hpp"
#include "gui/widgets/settings.hpp"
#include "hash.hpp"
#include "log.hpp"
#include "multiplayer_error_codes.hpp"
#include "map_settings.hpp"
#include "sound.hpp"
#include "statistics.hpp"
#include "utils/parse_network_address.hpp"
#include "wesnothd_connection.hpp"
#include "resources.hpp"
#include "replay.hpp"

#include "utils/functional.hpp"

#include <fstream>

static lg::log_domain log_mp("mp/main");
#define DBG_MP LOG_STREAM(debug, log_mp)
#define ERR_MP LOG_STREAM(err, log_mp)

namespace
{
/** Opens a new server connection and prompts the client for login credentials, if necessary. */
std::pair<wesnothd_connection_ptr, config> open_connection(std::string host)
{
    DBG_MP << "opening connection" << std::endl;

    wesnothd_connection_ptr sock(nullptr);
    if(host.empty()) {
        return std::make_pair(nullptr, config());
    }

    // shown_hosts is used to prevent the client being locked in a redirect loop.
    using hostpair = std::pair<std::string, std::string>;

    std::set<hostpair> shown_hosts;
    hostpair addr;
    try {
        addr = parse_network_address(host, "15000");
    } catch(const std::runtime_error&) {
        throw wesnothd_error(_("Invalid address specified for multiplayer server"));
    }
    shown_hosts.insert(addr);

    // Initializes the connection to the server.
    sock = std::make_unique<wesnothd_connection>(addr.first, addr.second);
    if(!sock) {
        return std::make_pair(nullptr, config());
    }

    // Start stage
    gui2::dialogs::loading_screen::progress(loading_stage::connect_to_server);

    // First, spin until we get a handshake from the server.
    sock->wait_for_handshake();

    gui2::dialogs::loading_screen::progress(loading_stage::waiting);

    config data;
    config initial_lobby_config;

    bool received_join_lobby = false;
    bool received_gamelist = false;

    // Then, log in and wait for the lobby/game join prompt.
    do {
        if(!sock) {
            return std::make_pair(nullptr, config());
        }

        data.clear();
        sock->wait_and_receive_data(data);

        if(data.has_child("reject") || data.has_attribute("version")) {
            std::string version;

            if(const config& reject = data.child("reject")) {
                version = reject["accepted_versions"].str();
            } else {
                // Backwards-compatibility "version" attribute
                version = data["version"].str();
            }

            utils::string_map i18n_symbols;
            i18n_symbols["required_version"] = version;
            i18n_symbols["your_version"] = game_config::wesnoth_version.str();

            const std::string errorstring = VGETTEXT("The server accepts versions '$required_version', but you are using version '$your_version'", i18n_symbols);
            throw wesnothd_error(errorstring);
        }

        // Check for "redirect" messages
        if(const config& redirect = data.child("redirect")) {
            auto redirect_host = redirect["host"].str();
            auto redirect_port = redirect["port"].str("15000");

            if(shown_hosts.find(hostpair(redirect_host, redirect_port)) != shown_hosts.end()) {
                throw wesnothd_error(_("Server-side redirect loop"));
            }

            shown_hosts.emplace(redirect_host, redirect_port);

            gui2::dialogs::loading_screen::progress(loading_stage::redirect);

            // Open a new connection with the new host and port.
            sock.reset();
            sock = std::make_unique<wesnothd_connection>(redirect_host, redirect_port);

            // Wait for new handshake.
            sock->wait_for_handshake();

            gui2::dialogs::loading_screen::progress(loading_stage::waiting);
            continue;
        }

        if(data.has_child("version")) {
            config cfg;
            config res;
            cfg["version"] = game_config::wesnoth_version.str();

            std::string info;
            std::ifstream infofile("./data/dist");
            if(infofile.is_open()){
                infofile >> info;
                infofile.close();

                if(info == "Default" || info == "Steam" || info == "SourceForge" || info == "Flatpak"
                 || info == "macOS App Store" || info == "Linux repository" || info == "iOS" || info == "Android"
                 || info == "BSD repository") {
                     cfg["client_source"] = info;
                } else {
                    cfg["client_source"] = "Default";
                }
            } else {
                cfg["client_source"] = "Default";
            }
            res.add_child("version", std::move(cfg));
            sock->send_data(res);
        }

        // Check for gamelist. This *must* be done before the mustlogin check
        // or else this loop will run ad-infinitum.
        if(data.has_child("gamelist")) {
            received_gamelist = true;

            // data should only contain the game and user lists at this point, so just swap it.
            std::swap(initial_lobby_config, data);
        }

        if(data.has_child("error")) {
            std::string error_message;
            config* error = &data.child("error");
            error_message = (*error)["message"].str();
            throw wesnothd_rejected_client_error(error_message);
        }

        // The only message we should get here is the admin authentication message.
        // It's sent after [join_lobby] and before the initial gamelist.
        if(const config& message = data.child("message")) {
            preferences::parse_admin_authentication(message["sender"], message["message"]);
        }

        // Continue if we did not get a direction to login
        if(!data.has_child("mustlogin")) {
            continue;
        }

        // Enter login loop
        for(;;) {
            std::string login = preferences::login();

            config response ;
            config& sp = response.add_child("login") ;
            sp["username"] = login ;

            sock->send_data(response);
            sock->wait_and_receive_data(data);

            gui2::dialogs::loading_screen::progress(loading_stage::login_response);

            config* warning = &data.child("warning");

            if(*warning) {
                std::string warning_msg;

                if((*warning)["warning_code"] == MP_NAME_INACTIVE_WARNING) {
                    warning_msg = VGETTEXT("The nickname ‘$nick’ is inactive. "
                        "You cannot claim ownership of this nickname until you "
                        "activate your account via email or ask an "
                        "administrator to do it for you.", {{"nick", login}});
                } else {
                    warning_msg = (*warning)["message"].str();
                }

                warning_msg += "\n\n";
                warning_msg += _("Do you want to continue?");

                if(gui2::show_message(_("Warning"), warning_msg, gui2::dialogs::message::yes_no_buttons) != gui2::retval::OK) {
                    return std::make_pair(wesnothd_connection_ptr(), config());
                } else {
                    continue;
                }
            }

            config* error = &data.child("error");

            // ... and get us out of here if the server did not complain
            if(!*error) break;

            do {
                std::string password = preferences::password(host, login);

                bool fall_through = (*error)["force_confirmation"].to_bool() ?
                    (gui2::show_message(_("Confirm"), (*error)["message"], gui2::dialogs::message::ok_cancel_buttons) == gui2::retval::CANCEL) :
                    false;

                const bool is_pw_request = !((*error)["password_request"].empty()) && !(password.empty());

                // If the server asks for a password, provide one if we can
                // or request a password reminder.
                // Otherwise or if the user pressed 'cancel' in the confirmation dialog
                // above go directly to the username/password dialog
                if(is_pw_request && !fall_through) {
                    if((*error)["phpbb_encryption"].to_bool()) {
                        // Apparently HTML key-characters are passed to the hashing functions of phpbb in this escaped form.
                        // I will do closer investigations on this, for now let's just hope these are all of them.

                        // Note: we must obviously replace '&' first, I wasted some time before I figured that out... :)
                        for(std::string::size_type pos = 0; (pos = password.find('&', pos)) != std::string::npos; ++pos)
                            password.replace(pos, 1, "&amp;");
                        for(std::string::size_type pos = 0; (pos = password.find('\"', pos)) != std::string::npos; ++pos)
                            password.replace(pos, 1, "&quot;");
                        for(std::string::size_type pos = 0; (pos = password.find('<', pos)) != std::string::npos; ++pos)
                            password.replace(pos, 1, "&lt;");
                        for(std::string::size_type pos = 0; (pos = password.find('>', pos)) != std::string::npos; ++pos)
                            password.replace(pos, 1, "&gt;");

                        const std::string salt = (*error)["salt"];

                        if(salt.length() < 12) {
                            throw wesnothd_error(_("Bad data received from server"));
                        }

                        if(utils::md5::is_valid_prefix(salt)) {
                            sp["password"] = utils::md5(utils::md5(password, utils::md5::get_salt(salt),
                                utils::md5::get_iteration_count(salt)).base64_digest(), salt.substr(12, 8)).base64_digest();
                        } else if(utils::bcrypt::is_valid_prefix(salt)) {
                            try {
                                auto bcrypt_salt = utils::bcrypt::from_salted_salt(salt);
                                auto hash = utils::bcrypt::hash_pw(password, bcrypt_salt);
                                std::string outer_salt = salt.substr(bcrypt_salt.iteration_count_delim_pos + 23);
                                if(outer_salt.size() != 32)
                                    throw utils::hash_error("salt wrong size");
                                sp["password"] = utils::md5(hash.base64_digest(), outer_salt).base64_digest();
                            } catch(const utils::hash_error& err) {
                                ERR_MP << "bcrypt hash failed: " << err.what() << std::endl;
                                throw wesnothd_error(_("Bad data received from server"));
                            }
                        } else {
                            throw wesnothd_error(_("Bad data received from server"));
                        }
                    } else {
                        sp["password"] = password;
                    }

                    // Once again send our request...
                    sock->send_data(response);
                    sock->wait_and_receive_data(data);

                    gui2::dialogs::loading_screen::progress(loading_stage::login_response);

                    error = &data.child("error");

                    // ... and get us out of here if the server is happy now
                    if(!*error) break;
                }

                // Providing a password either was not attempted because we did not
                // have any or failed:
                // Now show a dialog that displays the error and allows to
                // enter a new user name and/or password

                std::string error_message;
                utils::string_map i18n_symbols;
                i18n_symbols["nick"] = login;

                const bool has_extra_data = error->has_child("data");
                if(has_extra_data) {
                    i18n_symbols["duration"] = utils::format_timespan((*error).child("data")["duration"]);
                }

                if((*error)["error_code"] == MP_MUST_LOGIN) {
                    error_message = _("You must login first.");
                } else if((*error)["error_code"] == MP_NAME_TAKEN_ERROR) {
                    error_message = VGETTEXT("The nickname ‘$nick’ is already taken.", i18n_symbols);
                } else if((*error)["error_code"] == MP_INVALID_CHARS_IN_NAME_ERROR) {
                    error_message = VGETTEXT("The nickname ‘$nick’ contains invalid "
                            "characters. Only alpha-numeric characters (one at minimum), underscores and "
                            "hyphens are allowed.", i18n_symbols);
                } else if((*error)["error_code"] == MP_NAME_TOO_LONG_ERROR) {
                    error_message = VGETTEXT("The nickname ‘$nick’ is too long. Nicks must "
                            "be 20 characters or less.", i18n_symbols);
                } else if((*error)["error_code"] == MP_NAME_RESERVED_ERROR) {
                    error_message = VGETTEXT("The nickname ‘$nick’ is reserved and cannot be used by players.", i18n_symbols);
                } else if((*error)["error_code"] == MP_NAME_UNREGISTERED_ERROR) {
                    error_message = VGETTEXT("The nickname ‘$nick’ is not registered on this server.", i18n_symbols)
                            + _(" This server disallows unregistered nicknames.");
                } else if((*error)["error_code"] == MP_NAME_AUTH_BAN_USER_ERROR) {
                    if(has_extra_data) {
                        error_message = VGETTEXT("The nickname ‘$nick’ is banned on this server’s forums for $duration|.", i18n_symbols);
                    } else {
                        error_message = VGETTEXT("The nickname ‘$nick’ is banned on this server’s forums.", i18n_symbols);
                    }
                } else if((*error)["error_code"] == MP_NAME_AUTH_BAN_IP_ERROR) {
                    if(has_extra_data) {
                        error_message = VGETTEXT("Your IP address is banned on this server’s forums for $duration|.", i18n_symbols);
                    } else {
                        error_message = _("Your IP address is banned on this server’s forums.");
                    }
                } else if((*error)["error_code"] == MP_NAME_AUTH_BAN_EMAIL_ERROR) {
                    if(has_extra_data) {
                        error_message = VGETTEXT("The email address for the nickname ‘$nick’ is banned on this server’s forums for $duration|.", i18n_symbols);
                    } else {
                        error_message = VGETTEXT("The email address for the nickname ‘$nick’ is banned on this server’s forums.", i18n_symbols);
                    }
                } else if((*error)["error_code"] == MP_PASSWORD_REQUEST) {
                    error_message = VGETTEXT("The nickname ‘$nick’ is registered on this server.", i18n_symbols);
                } else if((*error)["error_code"] == MP_PASSWORD_REQUEST_FOR_LOGGED_IN_NAME) {
                    error_message = VGETTEXT("The nickname ‘$nick’ is registered on this server.", i18n_symbols)
                            + "\n\n" + _("WARNING: There is already a client using this nickname, "
                            "logging in will cause that client to be kicked!");
                } else if((*error)["error_code"] == MP_NO_SEED_ERROR) {
                    error_message = _("Error in the login procedure (the server had no "
                            "seed for your connection).");
                } else if((*error)["error_code"] == MP_INCORRECT_PASSWORD_ERROR) {
                    error_message = _("The password you provided was incorrect.");
                } else if((*error)["error_code"] == MP_TOO_MANY_ATTEMPTS_ERROR) {
                    error_message = _("You have made too many login attempts.");
                } else {
                    error_message = (*error)["message"].str();
                }

                gui2::dialogs::mp_login dlg(host, error_message, !((*error)["password_request"].empty()));

                // Need to show the dialog from the main thread or it won't appear.
                events::call_in_main_thread([&dlg]() { dlg.show(); });

                switch(dlg.get_retval()) {
                    //Log in with password
                    case gui2::retval::OK:
                        break;
                    // Cancel
                    default:
                        return std::make_pair(wesnothd_connection_ptr(), config());
                }

            // If we have got a new username we have to start all over again
            } while(login == preferences::login());

            // Somewhat hacky...
            // If we broke out of the do-while loop above error
            // is still going to be nullptr
            if(!*error) break;
        } // end login loop

        if(data.has_child("join_lobby")) {
            received_join_lobby = true;

            gui2::dialogs::loading_screen::progress(loading_stage::download_lobby_data);
        }
    } while(!received_join_lobby || !received_gamelist);

    return std::make_pair(std::move(sock), std::move(initial_lobby_config));
}

/** Helper struct to manage the MP workflow arguments. */
struct mp_workflow_helper
{
    mp_workflow_helper(const config& gc, saved_game& state, wesnothd_connection* connection, mp::lobby_info* li)
        : game_config(gc)
        , state(state)
        , connection(connection)
        , lobby_info(li)
    {}

    const config& game_config;

    saved_game& state;

    wesnothd_connection* connection;

    mp::lobby_info* lobby_info;
};

using mp_workflow_helper_ptr = std::shared_ptr<mp_workflow_helper>;

/**
 * The main components of the MP workflow. It consists of four screens:
 *
 * Host POV:   LOBBY <---> CREATE GAME ---> STAGING ------------------> GAME BEGINS
 * Player POV: LOBBY <---------------------------------> JOIN GAME ---> GAME BEGINS
 *
 * NOTE: since these functions are static, they appear here in the opposite order they'd be accessed.
 */
void enter_wait_mode(mp_workflow_helper_ptr helper, int game_id, bool observe)
{
    DBG_MP << "entering wait mode" << std::endl;

    // The connection should never be null here, since one should never reach this screen in local game mode.
    assert(helper->connection);

    statistics::fresh_stats();

    auto campaign_info = std::make_unique<mp_campaign_info>(*helper->connection);
    campaign_info->is_host = false;

    if(helper->lobby_info->get_game_by_id(game_id)) {
        campaign_info->current_turn = helper->lobby_info->get_game_by_id(game_id)->current_turn;
    }

    if(preferences::skip_mp_replay() || preferences::blindfold_replay()) {
        campaign_info->skip_replay = true;
        campaign_info->skip_replay_blindfolded = preferences::blindfold_replay();
    }

    bool dlg_ok = false;
    {
        gui2::dialogs::mp_join_game dlg(helper->state, *helper->lobby_info, *helper->connection, true, observe);

        if(!dlg.fetch_game_config()) {
            helper->connection->send_data(config("leave_game"));
            return;
        }

        dlg.show();
        dlg_ok = dlg.get_retval() == gui2::retval::OK;
    }

    if(dlg_ok) {
        campaign_controller controller(helper->state, game_config_manager::get()->terrain_types());
        controller.set_mp_info(campaign_info.get());
        controller.play_game();
    }

    helper->connection->send_data(config("leave_game"));
}

void enter_staging_mode(mp_workflow_helper_ptr helper)
{
    DBG_MP << "entering connect mode" << std::endl;

    std::unique_ptr<mp_campaign_info> campaign_info;

    // If we have a connection, set the appropriate info. No connection means we're in local game mode.
    if(helper->connection) {
        campaign_info.reset(new mp_campaign_info(*helper->connection));
        campaign_info->connected_players.insert(preferences::login());
        campaign_info->is_host = true;
    }

    bool dlg_ok = false;
    {
        ng::connect_engine_ptr connect_engine(new ng::connect_engine(helper->state, true, campaign_info.get()));

        gui2::dialogs::mp_staging dlg(*connect_engine, *helper->lobby_info, helper->connection);
        dlg.show();
        dlg_ok = dlg.get_retval() == gui2::retval::OK;
    } // end connect_engine_ptr, dlg scope

    if(dlg_ok) {
        campaign_controller controller(helper->state, game_config_manager::get()->terrain_types());
        controller.set_mp_info(campaign_info.get());
        controller.play_game();
    }

    if(helper->connection) {
        helper->connection->send_data(config("leave_game"));
    }
}

void enter_create_mode(mp_workflow_helper_ptr helper)
{
    DBG_MP << "entering create mode" << std::endl;

    bool dlg_ok = false;
    {
        bool local_mode = helper->connection == nullptr;
        mp::user_info* host_info = helper->lobby_info->get_user(preferences::login());

        gui2::dialogs::mp_create_game dlg(helper->game_config, helper->state, local_mode, host_info);
        dlg.show();

        // The Create Game dialog also has a LOAD_GAME retval besides OK.
        // Do a did-not-cancel check here to catch that
        dlg_ok = dlg.get_retval() != gui2::retval::CANCEL;
    }

    if(dlg_ok) {
        enter_staging_mode(helper);
    } else if(helper->connection) {
        helper->connection->send_data(config("refresh_lobby"));
    }
}

bool enter_lobby_mode(mp_workflow_helper_ptr helper, const std::vector<std::string>& installed_addons, const config& initial_lobby_config)
{
    DBG_MP << "entering lobby mode" << std::endl;

    // Connection should never be null in the lobby.
    assert(helper->connection);

    // We use a loop here to allow returning to the lobby if you, say, cancel game creation.
    while(true) {
        if(const config& cfg = helper->game_config.child("lobby_music")) {
            for(const config& i : cfg.child_range("music")) {
                sound::play_music_config(i);
            }

            sound::commit_music_changes();
        } else {
            sound::empty_playlist();
            sound::stop_music();
        }

        mp::lobby_info li(installed_addons);
        helper->lobby_info = &li;

        if(!initial_lobby_config.empty()) {
            li.process_gamelist(initial_lobby_config);
        }

        int dlg_retval = 0;
        int dlg_joined_game_id = 0;
        {

            gui2::dialogs::mp_lobby dlg(helper->game_config, li, *helper->connection);
            dlg.show();
            dlg_retval = dlg.get_retval();
            dlg_joined_game_id = dlg.get_joined_game_id();
        }

        switch(dlg_retval) {
            case gui2::dialogs::mp_lobby::CREATE:
                try {
                    enter_create_mode(helper);
                } catch(const config::error& error) {
                    if(!error.message.empty()) {
                        gui2::show_error_message(error.message);
                    }

                    // Update lobby content
                    helper->connection->send_data(config("refresh_lobby"));
                }

                break;
            case gui2::dialogs::mp_lobby::JOIN:
            case gui2::dialogs::mp_lobby::OBSERVE:
                try {
                    enter_wait_mode(helper,
                        dlg_joined_game_id,
                        dlg_retval == gui2::dialogs::mp_lobby::OBSERVE
                    );
                } catch(const config::error& error) {
                    if(!error.message.empty()) {
                        gui2::show_error_message(error.message);
                    }

                    // Update lobby content
                    helper->connection->send_data(config("refresh_lobby"));
                }

                break;
            case gui2::dialogs::mp_lobby::RELOAD_CONFIG:
                // Let this function's caller reload the config and re-call.
                return false;
            default:
                // Needed to handle the Quit signal and exit the loop
                return true;
        }
    }

    return true;
}

} // end anon namespace

/** Pubic entry points for the MP workflow */
namespace mp
{
void start_client(const config& game_config,    saved_game& state, const std::string& host)
{
    const config* game_config_ptr = &game_config;

    // This function does not refer to an addon database, it calls filesystem functions.
    // For the sanity of the mp lobby, this list should be fixed for the entire lobby session,
    // even if the user changes the contents of the addon directory in the meantime.
    std::vector<std::string> installed_addons = ::installed_addons();

    DBG_MP << "starting client" << std::endl;

    preferences::admin_authentication_reset r;

    wesnothd_connection_ptr connection;
    config lobby_config;

    gui2::dialogs::loading_screen::display([&]() {
        std::tie(connection, lobby_config) = open_connection(host);
    });

    if(!connection) {
        return;
    }

    mp_workflow_helper_ptr workflow_helper;
    bool re_enter = false;

    do {
        workflow_helper.reset(new mp_workflow_helper(*game_config_ptr, state, connection.get(), nullptr));

        // A return of false means a config reload was requested, so do that and then loop.
        re_enter = !enter_lobby_mode(workflow_helper, installed_addons, lobby_config);

        if(re_enter) {
            game_config_manager* gcm = game_config_manager::get();
            gcm->reload_changed_game_config();
            gcm->load_game_config_for_game(state.classification()); // NOTE: Using reload_changed_game_config only doesn't seem to work here

            game_config_ptr = &gcm->game_config();

            installed_addons = ::installed_addons(); // Refresh the installed add-on list for this session.

            connection->send_data(config("refresh_lobby"));
        }
    } while(re_enter);
}

bool goto_mp_connect(ng::connect_engine& engine, wesnothd_connection* connection)
{
    lobby_info li({});

    return gui2::dialogs::mp_staging::execute(engine, li, connection);
}

bool goto_mp_wait(saved_game& state, wesnothd_connection* connection, bool observe)
{
    lobby_info li({});

    gui2::dialogs::mp_join_game dlg(state, li, *connection, false, observe);

    if(!dlg.fetch_game_config()) {
        connection->send_data(config("leave_game"));
        return false;
    }

    if(dlg.started()) {
        return true;
    }

    return dlg.show();
}

void start_local_game(const config& game_config, saved_game& state)
{
    DBG_MP << "starting local game" << std::endl;

    preferences::set_message_private(false);

    // TODO: should lobby_info take a nullptr in this case, or should we pass the installed_addons data here too?
    lobby_info li({});
    mp_workflow_helper_ptr workflow_helper = std::make_shared<mp_workflow_helper>(game_config, state, nullptr, &li);

    enter_create_mode(workflow_helper);
}

void start_local_game_commandline(const config& game_config, saved_game& state, const commandline_options& cmdline_opts)
{
    DBG_MP << "starting local MP game from commandline" << std::endl;

    // The setup is done equivalently to lobby MP games using as much of existing
    // code as possible.  This means that some things are set up that are not
    // needed in commandline mode, but they are required by the functions called.
    preferences::set_message_private(false);

    DBG_MP << "entering create mode" << std::endl;

    // Set the default parameters
    state.clear(); // This creates these parameters with default values defined in mp_game_settings.cpp
    mp_game_settings& parameters = state.mp_settings();

    // Hardcoded default values
    parameters.mp_era = "era_default";
    parameters.name = "multiplayer_The_Freelands";

    // Default values for which at getter function exists
    parameters.num_turns = settings::get_turns("");
    parameters.village_gold = settings::get_village_gold("");
    parameters.village_support = settings::get_village_support("");
    parameters.xp_modifier = settings::get_xp_modifier("");

    // Do not use map settings if --ignore-map-settings commandline option is set
    if(cmdline_opts.multiplayer_ignore_map_settings) {
        DBG_MP << "ignoring map settings" << std::endl;
        parameters.use_map_settings = false;
    } else {
        parameters.use_map_settings = true;
    }

    // None of the other parameters need to be set, as their creation values above are good enough for CL mode.
    // In particular, we do not want to use the preferences values.

    state.classification().campaign_type = game_classification::CAMPAIGN_TYPE::MULTIPLAYER;

    // [era] define.
    if(cmdline_opts.multiplayer_era) {
        parameters.mp_era = *cmdline_opts.multiplayer_era;
    }

    if(const config& cfg_era = game_config.find_child("era", "id", parameters.mp_era)) {
        state.classification().era_define = cfg_era["define"].str();
    } else {
        std::cerr << "Could not find era '" << parameters.mp_era << "'\n";
        return;
    }

    // [multiplayer] define.
    if(cmdline_opts.multiplayer_scenario) {
        parameters.name = *cmdline_opts.multiplayer_scenario;
    }

    if(const config& cfg_multiplayer = game_config.find_child("multiplayer", "id", parameters.name)) {
        state.classification().scenario_define = cfg_multiplayer["define"].str();
    } else {
        std::cerr << "Could not find [multiplayer] '" << parameters.name << "'\n";
        return;
    }

    game_config_manager::get()->load_game_config_for_game(state.classification());
    state.set_carryover_sides_start(
        config {"next_scenario", parameters.name}
    );

    state.expand_random_scenario();
    state.expand_mp_events();
    state.expand_mp_options();

    // Should number of turns be determined from scenario data?
    if(parameters.use_map_settings && state.get_starting_point()["turns"]) {
        DBG_MP << "setting turns from scenario data: " << state.get_starting_point()["turns"] << std::endl;
        parameters.num_turns = state.get_starting_point()["turns"];
    }

    DBG_MP << "entering connect mode" << std::endl;

    statistics::fresh_stats();

    {
        ng::connect_engine_ptr connect_engine(new ng::connect_engine(state, true, nullptr));

        // Update the parameters to reflect game start conditions
        connect_engine->start_game_commandline(cmdline_opts, game_config);
    }

    if(resources::recorder && cmdline_opts.multiplayer_label) {
        std::string label = *cmdline_opts.multiplayer_label;
        resources::recorder->add_log_data("ai_log","ai_label",label);
    }

    unsigned int repeat = (cmdline_opts.multiplayer_repeat) ? *cmdline_opts.multiplayer_repeat : 1;
    for(unsigned int i = 0; i < repeat; i++){
        saved_game state_copy(state);
        campaign_controller controller(state_copy, game_config_manager::get()->terrain_types());
        controller.play_game();
    }
}

} // end namespace mp