Codechange: Update minimum CMake version to 3.16 for all parts. (#13141)

[openttd-github.git] / src / network / core / tcp_connect.cpp

/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * @file tcp_connect.cpp Basic functions to create connections without blocking.
 */

#include "../../stdafx.h"
#include "../../thread.h"

#include "tcp.h"
#include "../network_coordinator.h"
#include "../network_internal.h"

#include "../../safeguards.h"

/* static */ std::vector<std::shared_ptr<TCPConnecter>> TCPConnecter::connecters;

/**
 * Create a new connecter for the given address.
 * @param connection_string The address to connect to.
 * @param default_port If not indicated in connection_string, what port to use.
 * @param bind_address The local bind address to use. Defaults to letting the OS find one.
 */
TCPConnecter::TCPConnecter(const std::string &connection_string, uint16_t default_port, const NetworkAddress &bind_address, int family) :
        bind_address(bind_address),
        family(family)
{
        this->connection_string = NormalizeConnectionString(connection_string, default_port);
}

/**
 * Create a new connecter for the server.
 * @param connection_string The address to connect to.
 * @param default_port If not indicated in connection_string, what port to use.
 */
TCPServerConnecter::TCPServerConnecter(const std::string &connection_string, uint16_t default_port) :
        server_address(ServerAddress::Parse(connection_string, default_port))
{
        switch (this->server_address.type) {
                case SERVER_ADDRESS_DIRECT:
                        this->connection_string = this->server_address.connection_string;
                        break;

                case SERVER_ADDRESS_INVITE_CODE:
                        this->status = Status::Connecting;
                        _network_coordinator_client.ConnectToServer(this->server_address.connection_string, this);
                        break;

                default:
                        NOT_REACHED();
        }
}

TCPConnecter::~TCPConnecter()
{
        if (this->resolve_thread.joinable()) {
                this->resolve_thread.join();
        }

        for (const auto &socket : this->sockets) {
                closesocket(socket);
        }
        this->sockets.clear();
        this->sock_to_address.clear();

        if (this->ai != nullptr) freeaddrinfo(this->ai);
}

/**
 * Kill this connecter.
 * It will abort as soon as it can and not call any of the callbacks.
 */
void TCPConnecter::Kill()
{
        /* Delay the removing of the socket till the next CheckActivity(). */
        this->killed = true;
}

/**
 * Start a connection to the indicated address.
 * @param address The address to connection to.
 */
void TCPConnecter::Connect(addrinfo *address)
{
        SOCKET sock = socket(address->ai_family, address->ai_socktype, address->ai_protocol);
        if (sock == INVALID_SOCKET) {
                Debug(net, 0, "Could not create {} {} socket: {}", NetworkAddress::SocketTypeAsString(address->ai_socktype), NetworkAddress::AddressFamilyAsString(address->ai_family), NetworkError::GetLast().AsString());
                return;
        }

        if (!SetReusePort(sock)) {
                Debug(net, 0, "Setting reuse-port mode failed: {}", NetworkError::GetLast().AsString());
        }

        if (this->bind_address.GetPort() > 0) {
                if (bind(sock, (const sockaddr *)this->bind_address.GetAddress(), this->bind_address.GetAddressLength()) != 0) {
                        Debug(net, 1, "Could not bind socket on {}: {}", this->bind_address.GetAddressAsString(), NetworkError::GetLast().AsString());
                        closesocket(sock);
                        return;
                }
        }

        if (!SetNoDelay(sock)) {
                Debug(net, 1, "Setting TCP_NODELAY failed: {}", NetworkError::GetLast().AsString());
        }
        if (!SetNonBlocking(sock)) {
                Debug(net, 0, "Setting non-blocking mode failed: {}", NetworkError::GetLast().AsString());
        }

        NetworkAddress network_address = NetworkAddress(address->ai_addr, (int)address->ai_addrlen);
        Debug(net, 5, "Attempting to connect to {}", network_address.GetAddressAsString());

        int err = connect(sock, address->ai_addr, (int)address->ai_addrlen);
        if (err != 0 && !NetworkError::GetLast().IsConnectInProgress()) {
                closesocket(sock);

                Debug(net, 1, "Could not connect to {}: {}", network_address.GetAddressAsString(), NetworkError::GetLast().AsString());
                return;
        }

        this->sock_to_address[sock] = network_address;
        this->sockets.push_back(sock);
}

/**
 * Start the connect() for the next address in the list.
 * @return True iff a new connect() is attempted.
 */
bool TCPConnecter::TryNextAddress()
{
        if (this->current_address >= this->addresses.size()) return false;

        this->last_attempt = std::chrono::steady_clock::now();
        this->Connect(this->addresses[this->current_address++]);

        return true;
}

/**
 * Callback when resolving is done.
 * @param ai A linked-list of address information.
 */
void TCPConnecter::OnResolved(addrinfo *ai)
{
        std::deque<addrinfo *> addresses_ipv4, addresses_ipv6;

        /* Apply "Happy Eyeballs" if it is likely IPv6 is functional. */

        /* Detect if IPv6 is likely to succeed or not. */
        bool seen_ipv6 = false;
        bool resort = true;
        for (addrinfo *runp = ai; runp != nullptr; runp = runp->ai_next) {
                if (runp->ai_family == AF_INET6) {
                        seen_ipv6 = true;
                } else if (!seen_ipv6) {
                        /* We see an IPv4 before an IPv6; this most likely means there is
                         * no IPv6 available on the system, so keep the order of this
                         * list. */
                        resort = false;
                        break;
                }
        }

        /* Convert the addrinfo into NetworkAddresses. */
        for (addrinfo *runp = ai; runp != nullptr; runp = runp->ai_next) {
                /* Skip entries if the family is set and it is not matching. */
                if (this->family != AF_UNSPEC && this->family != runp->ai_family) continue;

                if (resort) {
                        if (runp->ai_family == AF_INET6) {
                                addresses_ipv6.emplace_back(runp);
                        } else {
                                addresses_ipv4.emplace_back(runp);
                        }
                } else {
                        this->addresses.emplace_back(runp);
                }
        }

        /* If we want to resort, make the list like IPv6 / IPv4 / IPv6 / IPv4 / ..
         * for how ever many (round-robin) DNS entries we have. */
        if (resort) {
                while (!addresses_ipv4.empty() || !addresses_ipv6.empty()) {
                        if (!addresses_ipv6.empty()) {
                                this->addresses.push_back(addresses_ipv6.front());
                                addresses_ipv6.pop_front();
                        }
                        if (!addresses_ipv4.empty()) {
                                this->addresses.push_back(addresses_ipv4.front());
                                addresses_ipv4.pop_front();
                        }
                }
        }

        if (_debug_net_level >= 6) {
                if (this->addresses.empty()) {
                        Debug(net, 6, "{} did not resolve", this->connection_string);
                } else {
                        Debug(net, 6, "{} resolved in:", this->connection_string);
                        for (const auto &address : this->addresses) {
                                Debug(net, 6, "- {}", NetworkAddress(address->ai_addr, (int)address->ai_addrlen).GetAddressAsString());
                        }
                }
        }

        this->current_address = 0;
}

/**
 * Start resolving the hostname.
 *
 * This function must change "status" to either Status::FAILURE
 * or Status::CONNECTING before returning.
 */
void TCPConnecter::Resolve()
{
        /* Port is already guaranteed part of the connection_string. */
        NetworkAddress address = ParseConnectionString(this->connection_string, 0);

        addrinfo hints;
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = AF_UNSPEC;
        hints.ai_flags = AI_ADDRCONFIG;
        hints.ai_socktype = SOCK_STREAM;

        std::string port_name = std::to_string(address.GetPort());

        static bool getaddrinfo_timeout_error_shown = false;
        auto start = std::chrono::steady_clock::now();

        addrinfo *ai;
        int error = getaddrinfo(address.GetHostname().c_str(), port_name.c_str(), &hints, &ai);

        auto end = std::chrono::steady_clock::now();
        auto duration = std::chrono::duration_cast<std::chrono::seconds>(end - start);
        if (!getaddrinfo_timeout_error_shown && duration >= std::chrono::seconds(5)) {
                Debug(net, 0, "getaddrinfo() for address \"{}\" took {} seconds", this->connection_string, duration.count());
                Debug(net, 0, "  This is likely an issue in the DNS name resolver's configuration causing it to time out");
                getaddrinfo_timeout_error_shown = true;
        }

        if (error != 0) {
                Debug(net, 0, "Failed to resolve DNS for {}", this->connection_string);
                this->status = Status::Failure;
                return;
        }

        this->ai = ai;
        this->OnResolved(ai);

        this->status = Status::Connecting;
}

/**
 * Thunk to start Resolve() on the right instance.
 */
/* static */ void TCPConnecter::ResolveThunk(TCPConnecter *connecter)
{
        connecter->Resolve();
}

/**
 * Check if there was activity for this connecter.
 * @return True iff the TCPConnecter is done and can be cleaned up.
 */
bool TCPConnecter::CheckActivity()
{
        if (this->killed) return true;

        switch (this->status) {
                case Status::Init:
                        /* Start the thread delayed, so the vtable is loaded. This allows classes
                         * to overload functions used by Resolve() (in case threading is disabled). */
                        if (StartNewThread(&this->resolve_thread, "ottd:resolve", &TCPConnecter::ResolveThunk, this)) {
                                this->status = Status::Resolving;
                                return false;
                        }

                        /* No threads, do a blocking resolve. */
                        this->Resolve();

                        /* Continue as we are either failed or can start the first
                         * connection. The rest of this function handles exactly that. */
                        break;

                case Status::Resolving:
                        /* Wait till Resolve() comes back with an answer (in case it runs threaded). */
                        return false;

                case Status::Failure:
                        /* Ensure the OnFailure() is called from the game-thread instead of the
                         * resolve-thread, as otherwise we can get into some threading issues. */
                        this->OnFailure();
                        return true;

                case Status::Connecting:
                case Status::Connected:
                        break;
        }

        /* If there are no attempts pending, connect to the next. */
        if (this->sockets.empty()) {
                if (!this->TryNextAddress()) {
                        /* There were no more addresses to try, so we failed. */
                        this->OnFailure();
                        return true;
                }
                return false;
        }

        fd_set write_fd;
        FD_ZERO(&write_fd);
        for (const auto &socket : this->sockets) {
                FD_SET(socket, &write_fd);
        }

        timeval tv;
        tv.tv_usec = 0;
        tv.tv_sec = 0;
        int n = select(FD_SETSIZE, nullptr, &write_fd, nullptr, &tv);
        /* select() failed; hopefully next try it doesn't. */
        if (n < 0) {
                /* select() normally never fails; so hopefully it works next try! */
                Debug(net, 1, "select() failed: {}", NetworkError::GetLast().AsString());
                return false;
        }

        /* No socket updates. */
        if (n == 0) {
                /* Wait 250ms between attempting another address. */
                if (std::chrono::steady_clock::now() < this->last_attempt + std::chrono::milliseconds(250)) return false;

                /* Try the next address in the list. */
                if (this->TryNextAddress()) return false;

                /* Wait up to 3 seconds since the last connection we started. */
                if (std::chrono::steady_clock::now() < this->last_attempt + std::chrono::milliseconds(3000)) return false;

                /* More than 3 seconds no socket reported activity, and there are no
                 * more address to try. Timeout the attempt. */
                Debug(net, 0, "Timeout while connecting to {}", this->connection_string);

                for (const auto &socket : this->sockets) {
                        closesocket(socket);
                }
                this->sockets.clear();
                this->sock_to_address.clear();

                this->OnFailure();
                return true;
        }

        /* If a socket is writeable, it is either in error-state or connected.
         * Remove all sockets that are in error-state and mark the first that is
         * not in error-state as the socket we will use for our connection. */
        SOCKET connected_socket = INVALID_SOCKET;
        for (auto it = this->sockets.begin(); it != this->sockets.end(); /* nothing */) {
                NetworkError socket_error = GetSocketError(*it);
                if (socket_error.HasError()) {
                        Debug(net, 1, "Could not connect to {}: {}", this->sock_to_address[*it].GetAddressAsString(), socket_error.AsString());
                        closesocket(*it);
                        this->sock_to_address.erase(*it);
                        it = this->sockets.erase(it);
                        continue;
                }

                /* No error but writeable means connected. */
                if (connected_socket == INVALID_SOCKET && FD_ISSET(*it, &write_fd)) {
                        connected_socket = *it;
                }

                it++;
        }

        /* All the writable sockets were in error state. So nothing is connected yet. */
        if (connected_socket == INVALID_SOCKET) return false;

        /* Close all sockets except the one we picked for our connection. */
        for (auto it = this->sockets.begin(); it != this->sockets.end(); /* nothing */) {
                if (connected_socket != *it) {
                        closesocket(*it);
                }
                this->sock_to_address.erase(*it);
                it = this->sockets.erase(it);
        }

        Debug(net, 3, "Connected to {}", this->connection_string);
        if (_debug_net_level >= 5) {
                Debug(net, 5, "- using {}", NetworkAddress::GetPeerName(connected_socket));
        }

        this->OnConnect(connected_socket);
        this->status = Status::Connected;
        return true;
}

/**
 * Check if there was activity for this connecter.
 * @return True iff the TCPConnecter is done and can be cleaned up.
 */
bool TCPServerConnecter::CheckActivity()
{
        if (this->killed) return true;

        switch (this->server_address.type) {
                case SERVER_ADDRESS_DIRECT:
                        return TCPConnecter::CheckActivity();

                case SERVER_ADDRESS_INVITE_CODE:
                        /* Check if a result has come in. */
                        switch (this->status) {
                                case Status::Failure:
                                        this->OnFailure();
                                        return true;

                                case Status::Connected:
                                        this->OnConnect(this->socket);
                                        return true;

                                default:
                                        break;
                        }

                        return false;

                default:
                        NOT_REACHED();
        }
}

/**
 * The connection was successfully established.
 * This socket is fully setup and ready to send/recv game protocol packets.
 * @param sock The socket of the established connection.
 */
void TCPServerConnecter::SetConnected(SOCKET sock)
{
        assert(sock != INVALID_SOCKET);

        this->socket = sock;
        this->status = Status::Connected;
}

/**
 * The connection couldn't be established.
 */
void TCPServerConnecter::SetFailure()
{
        this->status = Status::Failure;
}

/**
 * Check whether we need to call the callback, i.e. whether we
 * have connected or aborted and call the appropriate callback
 * for that. It's done this way to ease on the locking that
 * would otherwise be needed everywhere.
 */
/* static */ void TCPConnecter::CheckCallbacks()
{
        TCPConnecter::connecters.erase(
                std::remove_if(TCPConnecter::connecters.begin(), TCPConnecter::connecters.end(),
                                   [](auto &connecter) { return connecter->CheckActivity(); }),
                TCPConnecter::connecters.end());
}

/** Kill all connection attempts. */
/* static */ void TCPConnecter::KillAll()
{
        TCPConnecter::connecters.clear();
}