sernet.c

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/***********************************************************************
 Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   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, or (at your option)
   any later version.
 
   This program 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.
***********************************************************************/
 
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
#include "fc_prehdrs.h"
 
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
 
#ifdef FREECIV_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#ifdef FREECIV_HAVE_LIBREADLINE
#include <readline/history.h>
#include <readline/readline.h>
#endif
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
 
/* utility */
#include "capability.h"
#include "fciconv.h"
#include "fcintl.h"
#include "log.h"
#include "mem.h"
#include "netintf.h"
#include "shared.h"
#include "support.h"
#include "timing.h"
 
/* common */
#include "dataio.h"
#include "events.h"
#include "game.h"
#include "packets.h"
 
/* server/scripting */
#include "script_server.h"
 
/* server */
#include "aiiface.h"
#include "auth.h"
#include "connecthand.h"
#include "console.h"
#include "meta.h"
#include "plrhand.h"
#include "srv_main.h"
#include "stdinhand.h"
#include "voting.h"
 
#include "sernet.h"
 
static struct connection connections[MAX_NUM_CONNECTIONS];
 
#ifdef GENERATING_MAC      /* mac network globals */
TEndpointInfo serv_info;
EndpointRef serv_ep;
#else
static int *listen_socks;
static int listen_count;
static int socklan;
#endif
 
#if defined(__VMS)
#  if defined(_VAX_)
#    define lib$stop LIB$STOP
#    define sys$qiow SYS$QIOW
#    define sys$assign SYS$ASSIGN
#  endif
#  include <descrip.h>
#  include <iodef.h>
#  include <stsdef.h>
#  include <starlet.h>
#  include <lib$routines.h>
#  include <efndef.h>
   static unsigned long int tt_chan;
   static char input_char = 0;
   static char got_input = 0;
   void user_interrupt_callback();
#endif
 
#define PROCESSING_TIME_STATISTICS 0
 
static int server_accept_connection(int sockfd);
static void start_processing_request(struct connection *pconn,
                                     int request_id);
static void finish_processing_request(struct connection *pconn);
static void connection_ping(struct connection *pconn);
static void send_ping_times_to_all(void);
 
static void get_lanserver_announcement(void);
static void send_lanserver_response(void);
 
static bool no_input = FALSE;
 
/* Avoid compiler warning about defined, but unused function
 * by defining it only when needed */
#if defined(FREECIV_HAVE_LIBREADLINE) || \
    (!defined(FREECIV_SOCKET_ZERO_NOT_STDIN) && !defined(FREECIV_HAVE_LIBREADLINE))
/*************************************************************************/
static void handle_stdin_close(void)
{
  /* Note this function may be called even if FREECIV_SOCKET_ZERO_NOT_STDIN, so
   * the preprocessor check has to come inside the function body.  But
   * perhaps we want to do this even when FREECIV_SOCKET_ZERO_NOT_STDIN? */
#ifndef FREECIV_SOCKET_ZERO_NOT_STDIN
  log_normal(_("Server cannot read standard input. Ignoring input."));
  no_input = TRUE;
#endif /* FREECIV_SOCKET_ZERO_NOT_STDIN */
}
 
#endif /* FREECIV_HAVE_LIBREADLINE || (!FREECIV_SOCKET_ZERO_NOT_STDIN && !FREECIV_HAVE_LIBREADLINE) */
 
static char *current_internal = NULL;
 
#ifdef FREECIV_HAVE_LIBREADLINE
/****************************************************************************/
 
#define HISTORY_FILENAME  "freeciv-server_history"
#define HISTORY_LENGTH    100
 
static char *history_file = NULL;
static bool readline_handled_input = FALSE;
static bool readline_initialized = FALSE;
 
/*************************************************************************/
static void handle_readline_input_callback(char *line)
{
  if (no_input) {
    return;
  }
 
  if (line == NULL) {
    handle_stdin_close();       /* maybe print an 'are you sure?' message? */
    return;
  }
 
  if (line[0] != '\0') {
    add_history(line);
  }
 
  con_prompt_enter();           /* just got an 'Enter' hit */
  current_internal = local_to_internal_string_malloc(line);
  free(line); /* This is already freed if we exit() with /quit command */
  handle_stdin_input_free(NULL, current_internal);
  current_internal = NULL;
 
  readline_handled_input = TRUE;
}
#endif /* FREECIV_HAVE_LIBREADLINE */
 
/*************************************************************************/
void readline_atexit(void)
{
#ifdef FREECIV_HAVE_LIBREADLINE
  if (readline_initialized) {
    rl_callback_handler_remove();
    readline_initialized = FALSE;
  }
#endif /* FREECIV_HAVE_LIBREADLINE */
 
  if (current_internal != NULL) {
    free(current_internal);
    current_internal = NULL;
  }
}
 
/*************************************************************************/
static void close_connection(struct connection *pconn)
{
  if (!pconn) {
    return;
  }
 
  if (pconn->server.ping_timers != NULL) {
    timer_list_destroy(pconn->server.ping_timers);
    pconn->server.ping_timers = NULL;
  }
 
  conn_pattern_list_destroy(pconn->server.ignore_list);
  pconn->server.ignore_list = NULL;
 
  /* safe to do these even if not in lists: */
  conn_list_remove(game.glob_observers, pconn);
  conn_list_remove(game.all_connections, pconn);
  conn_list_remove(game.est_connections, pconn);
 
  pconn->playing = NULL;
  pconn->client_gui = GUI_STUB;
  pconn->access_level = ALLOW_NONE;
  connection_common_close(pconn);
 
  send_updated_vote_totals(NULL);
}
 
/*************************************************************************/
void close_connections_and_socket(void)
{
  int i;
 
  lsend_packet_server_shutdown(game.all_connections);
 
  for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
    if (connections[i].used) {
      close_connection(&connections[i]);
    }
    conn_list_destroy(connections[i].self);
  }
 
  /* Remove the game connection lists and make sure they are empty. */
  conn_list_destroy(game.glob_observers);
  conn_list_destroy(game.all_connections);
  conn_list_destroy(game.est_connections);
 
  for (i = 0; i < listen_count; i++) {
    fc_closesocket(listen_socks[i]);
  }
  FC_FREE(listen_socks);
 
  if (srvarg.announce != ANNOUNCE_NONE) {
    fc_closesocket(socklan);
  }
 
#ifdef FREECIV_HAVE_LIBREADLINE
  if (history_file) {
    write_history(history_file);
    history_truncate_file(history_file, HISTORY_LENGTH);
    free(history_file);
    history_file = NULL;
    clear_history();
  }
#endif /* FREECIV_HAVE_LIBREADLINE */
 
  send_server_info_to_metaserver(META_GOODBYE);
  server_close_meta();
 
  packets_deinit();
  fc_shutdown_network();
}
 
/*************************************************************************/
static void really_close_connections(void)
{
  struct connection *closing[MAX_NUM_CONNECTIONS];
  struct connection *pconn;
  int i, num;
 
  do {
    num = 0;
 
    for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
      pconn = connections + i;
      if (pconn->used && pconn->server.is_closing) {
        closing[num++] = pconn;
        /* Remove closing connections from the lists (hard detach)
         * to avoid sending to closing connections. */
        conn_list_remove(game.glob_observers, pconn);
        conn_list_remove(game.est_connections, pconn);
        conn_list_remove(game.all_connections, pconn);
        if (NULL != conn_get_player(pconn)) {
          conn_list_remove(conn_get_player(pconn)->connections, pconn);
        }
      }
    }
 
    for (i = 0; i < num; i++) {
      /* Now really close them. */
      pconn = closing[i];
      lost_connection_to_client(pconn);
      close_connection(pconn);
    }
  } while (0 < num); /* May some errors occurred, let's check. */
}
 
/*************************************************************************/
static void server_conn_close_callback(struct connection *pconn)
{
  /* Do as little as possible here to avoid recursive evil. */
  pconn->server.is_closing = TRUE;
}
 
/*************************************************************************/
static void cut_lagging_connection(struct connection *pconn)
{
  if (!pconn->server.is_closing
      && game.server.tcptimeout != 0
      && pconn->last_write
      && conn_list_size(game.all_connections) > 1
      && pconn->access_level != ALLOW_HACK
      && timer_read_seconds(pconn->last_write) > game.server.tcptimeout) {
    /* Cut the connections to players who lag too much.  This
     * usually happens because client animation slows the client
     * too much and it can't keep up with the server.  We don't
     * cut HACK connections, or cut in single-player games, since
     * it wouldn't help the game progress.  For other connections
     * the best thing to do when they lag too much is to be
     * disconnected and reconnect. */
    log_verbose("connection (%s) cut due to lagging player",
                conn_description(pconn));
    connection_close_server(pconn, _("lagging connection"));
  }
}
 
/*************************************************************************/
void flush_packets(void)
{
  int i;
  int max_desc;
  fd_set writefs, exceptfs;
  fc_timeval tv;
  time_t start;
 
  (void) time(&start);
 
  for (;;) {
    /* Can't assign to tv.tv_sec directly on systems where it's unsigned */
    signed signsecs = (game.server.netwait - (time(NULL) - start));
 
    if (signsecs < 0) {
      return;
    }
 
    tv.tv_usec = 0;
    tv.tv_sec = signsecs;
 
    FC_FD_ZERO(&writefs);
    FC_FD_ZERO(&exceptfs);
    max_desc = -1;
 
    for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
      struct connection *pconn = &connections[i];
 
      if (pconn->used
          && !pconn->server.is_closing
          && 0 < pconn->send_buffer->ndata) {
        FD_SET(pconn->sock, &writefs);
        FD_SET(pconn->sock, &exceptfs);
        max_desc = MAX(pconn->sock, max_desc);
      }
    }
 
    if (max_desc == -1) {
      return;
    }
 
    if (fc_select(max_desc + 1, NULL, &writefs, &exceptfs, &tv) <= 0) {
      return;
    }
 
    for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {   /* check for freaky players */
      struct connection *pconn = &connections[i];
 
      if (pconn->used && !pconn->server.is_closing) {
        if (FD_ISSET(pconn->sock, &exceptfs)) {
          log_verbose("connection (%s) cut due to exception data",
                      conn_description(pconn));
          connection_close_server(pconn, _("network exception"));
        } else {
          if (pconn->send_buffer && pconn->send_buffer->ndata > 0) {
            if (FD_ISSET(pconn->sock, &writefs)) {
              flush_connection_send_buffer_all(pconn);
            } else {
              cut_lagging_connection(pconn);
            }
          }
        }
      }
    }
  }
}
 
struct packet_to_handle {
  void *data;
  enum packet_type type;
};
 
/*************************************************************************/
static bool get_packet(struct connection *pconn, 
                       struct packet_to_handle *ppacket)
{
  ppacket->data = get_packet_from_connection(pconn, &ppacket->type);
 
  return NULL != ppacket->data;
}
 
/*************************************************************************/
static void incoming_client_packets(struct connection *pconn) 
{
  struct packet_to_handle packet;
#if PROCESSING_TIME_STATISTICS
  struct timer *request_time = NULL;
#endif
 
  while (get_packet(pconn, &packet)) {
    bool command_ok;
 
#if PROCESSING_TIME_STATISTICS
    int request_id;
 
    request_time = timer_renew(request_time, TIMER_USER, TIMER_ACTIVE);
    timer_start(request_time);
#endif /* PROCESSING_TIME_STATISTICS */
 
    pconn->server.last_request_id_seen
      = get_next_request_id(pconn->server.last_request_id_seen);
 
#if PROCESSING_TIME_STATISTICS
    request_id = pconn->server.last_request_id_seen;
#endif /* PROCESSING_TIME_STATISTICS */
 
    connection_do_buffer(pconn);
    start_processing_request(pconn, pconn->server.last_request_id_seen);
 
    command_ok = server_packet_input(pconn, packet.data, packet.type);
    free(packet.data);
 
    finish_processing_request(pconn);
    connection_do_unbuffer(pconn);
 
#if PROCESSING_TIME_STATISTICS
    log_verbose("processed request %d in %gms", request_id, 
                timer_read_seconds(request_time) * 1000.0);
#endif /* PROCESSING_TIME_STATISTICS */
 
    if (!command_ok) {
      connection_close_server(pconn, _("rejected"));
    }
  }
 
#if PROCESSING_TIME_STATISTICS
  timer_destroy(request_time);
#endif /* PROCESSING_TIME_STATISTICS */
}
 
/*************************************************************************/
enum server_events server_sniff_all_input(void)
{
  int i, s;
  int max_desc;
  bool excepting;
  fd_set readfs, writefs, exceptfs;
  fc_timeval tv;
#ifdef FREECIV_SOCKET_ZERO_NOT_STDIN
  char *bufptr;
#endif
 
  con_prompt_init();
 
#ifdef FREECIV_HAVE_LIBREADLINE
  {
    if (!no_input && !readline_initialized) {
      char *storage_dir = freeciv_storage_dir();
 
      if (storage_dir != NULL) {
        int fcdl = strlen(storage_dir) + 1;
        char *fc_dir = fc_malloc(fcdl);
 
        if (fc_dir != NULL) {
          fc_snprintf(fc_dir, fcdl, "%s", storage_dir);
 
          if (make_dir(fc_dir)) {
            history_file
              = fc_malloc(strlen(fc_dir) + 1 + strlen(HISTORY_FILENAME) + 1);
            if (history_file) {
              strcpy(history_file, fc_dir);
              strcat(history_file, "/");
              strcat(history_file, HISTORY_FILENAME);
              using_history();
              read_history(history_file);
            }
          }
          FC_FREE(fc_dir);
        }
      }
 
      rl_initialize();
      rl_callback_handler_install((char *) "> ",
                                  handle_readline_input_callback);
      rl_attempted_completion_function = freeciv_completion;
 
      readline_initialized = TRUE;
      atexit(readline_atexit);
    }
  }
#endif /* FREECIV_HAVE_LIBREADLINE */
 
  while (TRUE) {
    int selret;
 
    con_prompt_on();   /* accepting new input */
 
    if (force_end_of_sniff) {
      force_end_of_sniff = FALSE;
      con_prompt_off();
      return S_E_FORCE_END_OF_SNIFF;
    }
 
    get_lanserver_announcement();
 
    /* end server if no players for 'srvarg.quitidle' seconds,
     * but only if at least one player has previously connected. */
    if (srvarg.quitidle != 0) {
      static time_t last_noplayers;
      static bool conns;
 
      if (conn_list_size(game.est_connections) > 0) {
        conns = TRUE;
      }
      if (conns && conn_list_size(game.est_connections) == 0) {
        if (last_noplayers != 0) {
          if (time(NULL) > last_noplayers + srvarg.quitidle) {
            save_game_auto("Lost all connections", AS_QUITIDLE);
 
            if (srvarg.exit_on_end) {
              log_normal(_("Shutting down for lack of players."));
              set_meta_message_string("shutting down for lack of players");
            } else {
              log_normal(_("Restarting for lack of players."));
              set_meta_message_string("restarting for lack of players");
            }
            (void) send_server_info_to_metaserver(META_INFO);
 
            set_server_state(S_S_OVER);
            force_end_of_sniff = TRUE;
 
            if (srvarg.exit_on_end) {
              /* No need for anything more; just quit. */
              server_quit();
            }
 
            /* Do not restart before someone has connected and left again */
            conns = FALSE;
          }
        } else {
          last_noplayers = time(NULL);
 
          if (srvarg.exit_on_end) {
            log_normal(_("Shutting down in %d seconds for lack of players."),
                       srvarg.quitidle);
 
            set_meta_message_string(N_("shutting down soon for lack of players"));
          } else {
            log_normal(_("Restarting in %d seconds for lack of players."),
                       srvarg.quitidle);
 
            set_meta_message_string(N_("restarting soon for lack of players"));
          }
          (void) send_server_info_to_metaserver(META_INFO);
        }
      } else {
        last_noplayers = 0;
      }
    }
 
    /* Pinging around for statistics */
    if (time(NULL) > (game.server.last_ping + game.server.pingtime)) {
      /* send data about the previous run */
      send_ping_times_to_all();
 
      conn_list_iterate(game.all_connections, pconn) {
        if ((!pconn->server.is_closing
             && 0 < timer_list_size(pconn->server.ping_timers)
             && timer_read_seconds(timer_list_front
                                   (pconn->server.ping_timers))
                > game.server.pingtimeout) 
            || pconn->ping_time > game.server.pingtimeout) {
          /* cut mute players, except for hack-level ones */
          if (pconn->access_level == ALLOW_HACK) {
            log_verbose("connection (%s) [hack-level] ping timeout ignored",
                        conn_description(pconn));
          } else {
            log_verbose("connection (%s) cut due to ping timeout",
                        conn_description(pconn));
            connection_close_server(pconn, _("ping timeout"));
          }
        } else if (pconn->established) {
          /* We don't send ping to connection not established, because
           * we wouldn't be able to handle asynchronous ping/pong with
           * different packet header size. */
          connection_ping(pconn);
        }
      } conn_list_iterate_end;
      game.server.last_ping = time(NULL);
    }
 
    /* if we've waited long enough after a failure, respond to the client */
    conn_list_iterate(game.all_connections, pconn) {
      if (srvarg.auth_enabled
          && !pconn->server.is_closing
          && pconn->server.status != AS_ESTABLISHED) {
        auth_process_status(pconn);
      }
    } conn_list_iterate_end
 
    /* Don't wait if timeout == -1 (i.e. on auto games) */
    if (S_S_RUNNING == server_state() && game.info.timeout == -1) {
      call_ai_refresh();
      script_server_signal_emit("pulse");
      (void) send_server_info_to_metaserver(META_REFRESH);
      return S_E_END_OF_TURN_TIMEOUT;
    }
 
    tv.tv_sec = 1;
    tv.tv_usec = 0;
 
    FC_FD_ZERO(&readfs);
    FC_FD_ZERO(&writefs);
    FC_FD_ZERO(&exceptfs);
 
    if (!no_input) {
#ifdef FREECIV_SOCKET_ZERO_NOT_STDIN
      fc_init_console();
#else /* FREECIV_SOCKET_ZERO_NOT_STDIN */
#   if !defined(__VMS)
      FD_SET(0, &readfs);
#   endif /* VMS */
#endif /* FREECIV_SOCKET_ZERO_NOT_STDIN */
    }
 
    max_desc = 0;
    for (i = 0; i < listen_count; i++) {
      FD_SET(listen_socks[i], &readfs);
      FD_SET(listen_socks[i], &exceptfs);
      max_desc = MAX(max_desc, listen_socks[i]);
    }
 
    for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
      struct connection *pconn = connections + i;
 
      if (pconn->used && !pconn->server.is_closing) {
        FD_SET(pconn->sock, &readfs);
        if (0 < pconn->send_buffer->ndata) {
          FD_SET(pconn->sock, &writefs);
        }
        FD_SET(pconn->sock, &exceptfs);
        max_desc = MAX(pconn->sock, max_desc);
      }
    }
    con_prompt_off();           /* output doesn't generate a new prompt */
 
    selret = fc_select(max_desc + 1, &readfs, &writefs, &exceptfs, &tv);
    if (selret == 0) {
      /* timeout */
      call_ai_refresh();
      script_server_signal_emit("pulse");
      (void) send_server_info_to_metaserver(META_REFRESH);
      if (current_turn_timeout() > 0
          && S_S_RUNNING == server_state()
          && game.server.phase_timer
          && (timer_read_seconds(game.server.phase_timer)
              + game.server.additional_phase_seconds
              > game.tinfo.seconds_to_phasedone)) {
        con_prompt_off();
        return S_E_END_OF_TURN_TIMEOUT;
      }
      if ((game.server.autosaves & (1 << AS_TIMER))
          && S_S_RUNNING == server_state()
          && (timer_read_seconds(game.server.save_timer)
              >= game.server.save_frequency * 60)) {
        save_game_auto("Timer", AS_TIMER);
        game.server.save_timer = timer_renew(game.server.save_timer,
                                             TIMER_USER, TIMER_ACTIVE);
        timer_start(game.server.save_timer);
      }
 
      if (!no_input) {
#if defined(__VMS)
        {
          struct {
            short numchars;
            char firstchar;
            char reserved;
            int reserved2;
          } ttchar;
          unsigned long status;
 
          status = sys$qiow(EFN$C_ENF, tt_chan,
                            IO$_SENSEMODE | IO$M_TYPEAHDCNT, 0, 0, 0,
                            &ttchar, sizeof(ttchar), 0, 0, 0, 0);
          if (!$VMS_STATUS_SUCCESS(status)) {
            lib$stop(status);
          }
          if (ttchar.numchars) {
            FD_SET(0, &readfs);
          } else {
            continue;
          }
        }
#else  /* !__VMS */
#ifndef FREECIV_SOCKET_ZERO_NOT_STDIN
        really_close_connections();
        continue;
#endif /* FREECIV_SOCKET_ZERO_NOT_STDIN */
#endif /* !__VMS */
      }
    } else if (selret < 0) {
      log_error("fc_select() failed: %s", fc_strerror(fc_get_errno()));
    }
 
    excepting = FALSE;
    for (i = 0; i < listen_count; i++) {
      if (FD_ISSET(listen_socks[i], &exceptfs)) {
        excepting = TRUE;
        break;
      }
    }
    if (excepting) {                  /* handle Ctrl-Z suspend/resume */
      continue;
    }
    for (i = 0; i < listen_count; i++) {
      s = listen_socks[i];
      if (FD_ISSET(s, &readfs)) {     /* new players connects */
        log_verbose("got new connection");
        if (-1 == server_accept_connection(s)) {
          /* There will be a log_error() message from
           * server_accept_connection() if something
           * goes wrong, so no need to make another
           * error-level message here. */
          log_verbose("failed accepting connection");
        }
      }
    }
    for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
      /* check for freaky players */
      struct connection *pconn = &connections[i];
 
      if (pconn->used
          && !pconn->server.is_closing
          && FD_ISSET(pconn->sock, &exceptfs)) {
        log_verbose("connection (%s) cut due to exception data",
                    conn_description(pconn));
        connection_close_server(pconn, _("network exception"));
      }
    }
#ifdef FREECIV_SOCKET_ZERO_NOT_STDIN
    if (!no_input && (bufptr = fc_read_console())) {
      current_internal = local_to_internal_string_malloc(bufptr);
 
      con_prompt_enter();      /* Will need a new prompt, regardless */
      handle_stdin_input_free(NULL, current_internal);
      current_internal = NULL;
    }
#else  /* !FREECIV_SOCKET_ZERO_NOT_STDIN */
    if (!no_input && FD_ISSET(0, &readfs)) {    /* input from server operator */
#ifdef FREECIV_HAVE_LIBREADLINE
      rl_callback_read_char();
      if (readline_handled_input) {
        readline_handled_input = FALSE;
        con_prompt_enter_clear();
      }
      continue;
#else  /* !FREECIV_HAVE_LIBREADLINE */
      ssize_t didget;
      char *buffer;
 
#ifdef HAVE_GETLINE
      size_t len = 0;
 
      buffer = NULL; /* Must be NULL when calling getline() */
      didget = getline(&buffer, &len, stdin);
      if (didget >= 1) {
        buffer[--didget] = '\0'; /* Overwrite newline character */
        log_debug("Got line: \"%s\" (" SIZE_T_PRINTF ", " SIZE_T_PRINTF ")", buffer,
                  didget, len);
      }
#else  /* HAVE_GETLINE */
      buffer = malloc(BUF_SIZE + 1);
 
      didget = read(0, buffer, BUF_SIZE);
      if (didget > 0) {
        buffer[didget] = '\0';
      } else {
        didget = -1; /* Error or end-of-file: closing stdin... */
      }
#endif /* HAVE_GETLINE */
      if (didget < 0) {
        handle_stdin_close();
      }
 
      con_prompt_enter();       /* Will need a new prompt, regardless */
 
      if (didget >= 0) {
        current_internal = local_to_internal_string_malloc(buffer);
        handle_stdin_input_free(NULL, current_internal);
        current_internal = NULL;
      }
      free(buffer);
#endif /* !FREECIV_HAVE_LIBREADLINE */
    } else
#endif /* !FREECIV_SOCKET_ZERO_NOT_STDIN */
 
    {                             /* Input from a player */
      for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
        struct connection *pconn = connections + i;
        int nb;
 
        if (!pconn->used
            || pconn->server.is_closing
            || !FD_ISSET(pconn->sock, &readfs)) {
          continue;
        }
 
        nb = read_socket_data(pconn->sock, pconn->buffer);
        if (0 <= nb) {
          /* We read packets; now handle them. */
          incoming_client_packets(pconn);
        } else if (-2 == nb) {
          connection_close_server(pconn, _("client disconnected"));
        } else {
          /* Read failure; the connection is closed. */
          connection_close_server(pconn, _("read error"));
        }
      }
 
      for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
        struct connection *pconn = &connections[i];
 
        if (pconn->used
            && !pconn->server.is_closing
            && pconn->send_buffer
            && pconn->send_buffer->ndata > 0) {
          if (FD_ISSET(pconn->sock, &writefs)) {
            flush_connection_send_buffer_all(pconn);
          } else {
            cut_lagging_connection(pconn);
          }
        }
      }
      really_close_connections();
      break;
    }
  }
  con_prompt_off();
 
  call_ai_refresh();
  script_server_signal_emit("pulse");
 
  if (current_turn_timeout() > 0
      && S_S_RUNNING == server_state()
      && game.server.phase_timer
      && (timer_read_seconds(game.server.phase_timer)
          + game.server.additional_phase_seconds
          > game.tinfo.seconds_to_phasedone)) {
    return S_E_END_OF_TURN_TIMEOUT;
  }
  if ((game.server.autosaves & (1 << AS_TIMER))
      && S_S_RUNNING == server_state()
      && (timer_read_seconds(game.server.save_timer)
          >= game.server.save_frequency * 60)) {
    save_game_auto("Timer", AS_TIMER);
    game.server.save_timer = timer_renew(game.server.save_timer,
                                         TIMER_USER, TIMER_ACTIVE);
    timer_start(game.server.save_timer);
  }
 
  return S_E_OTHERWISE;
}
 
/*************************************************************************/
static const char *makeup_connection_name(int *id)
{
  static unsigned short i = 0;
  static char name[MAX_LEN_NAME];
 
  for (;;) {
    if (i == (unsigned short) - 1) {
      /* don't use 0 */
      i++;
    }
    fc_snprintf(name, sizeof(name), "c%u", (unsigned int)++i);
    if (NULL == player_by_name(name)
        && NULL == player_by_user(name)
        && NULL == conn_by_number(i)
        && NULL == conn_by_user(name)) {
      *id = i;
      return name;
    }
  }
}
 
/*************************************************************************/
static int server_accept_connection(int sockfd)
{
  /* This used to have size_t for some platforms.  If this is necessary
   * it should be done with a configure check not a platform check. */
  socklen_t fromlen;
 
  int new_sock;
  union fc_sockaddr fromend;
  bool nameinfo = FALSE;
#ifdef FREECIV_IPV6_SUPPORT
  char host[NI_MAXHOST], service[NI_MAXSERV];
  char dst[INET6_ADDRSTRLEN];
#else  /* IPv6 support */
  struct hostent *from;
  const char *host = NULL;
  const char *dst;
#endif /* IPv6 support */
 
  fromlen = sizeof(fromend);
 
  if ((new_sock = accept(sockfd, &fromend.saddr, &fromlen)) == -1) {
    log_error("accept failed: %s", fc_strerror(fc_get_errno()));
    return -1;
  }
 
#ifdef FREECIV_IPV6_SUPPORT
  if (fromend.saddr.sa_family == AF_INET6) {
    inet_ntop(AF_INET6, &fromend.saddr_in6.sin6_addr,
              dst, sizeof(dst));
  } else if (fromend.saddr.sa_family == AF_INET) {
    inet_ntop(AF_INET, &fromend.saddr_in4.sin_addr, dst, sizeof(dst));
  } else {
    fc_assert(FALSE);
 
    log_error("Unsupported address family in server_accept_connection()");
 
    return -1;
  }
#else  /* IPv6 support */
  dst = inet_ntoa(fromend.saddr_in4.sin_addr);
#endif /* IPv6 support */
 
  if (0 != game.server.maxconnectionsperhost) {
    int count = 0;
 
    conn_list_iterate(game.all_connections, pconn) {
      if (0 != strcmp(dst, pconn->server.ipaddr)) {
        continue;
      }
      if (++count >= game.server.maxconnectionsperhost) {
        log_verbose("Rejecting new connection from %s: maximum number of "
                    "connections for this address exceeded (%d).",
                    dst, game.server.maxconnectionsperhost);
 
        /* Disconnect the accepted socket. */
        fc_closesocket(new_sock);
 
        return -1;
      }
    } conn_list_iterate_end;
  }
 
#ifdef FREECIV_IPV6_SUPPORT
  nameinfo = (0 == getnameinfo(&fromend.saddr, fromlen, host, NI_MAXHOST,
                               service, NI_MAXSERV, NI_NUMERICSERV)
              && '\0' != host[0]);
#else  /* IPv6 support */
  from = gethostbyaddr((char *) &fromend.saddr_in4.sin_addr,
                       sizeof(fromend.saddr_in4.sin_addr), AF_INET);
  if (NULL != from && '\0' != from->h_name[0]) {
    host = from->h_name;
    nameinfo = TRUE;
  }
#endif /* IPv6 support */
 
  return server_make_connection(new_sock,
                                (nameinfo ? host : dst), dst);
}
 
/*************************************************************************/
int server_make_connection(int new_sock, const char *client_addr,
                           const char *client_ip)
{
  struct timer *timer;
  int i;
 
  fc_nonblock(new_sock);
 
  for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
    struct connection *pconn = &connections[i];
 
    if (!pconn->used) {
      connection_common_init(pconn);
      pconn->sock = new_sock;
      pconn->observer = FALSE;
      pconn->playing = NULL;
      pconn->capability[0] = '\0';
      pconn->access_level = access_level_for_next_connection();
      pconn->notify_of_writable_data = NULL;
      pconn->server.currently_processed_request_id = 0;
      pconn->server.last_request_id_seen = 0;
      pconn->server.auth_tries = 0;
      pconn->server.auth_settime = 0;
      pconn->server.status = AS_NOT_ESTABLISHED;
      pconn->server.ping_timers = timer_list_new_full(timer_destroy);
      pconn->server.granted_access_level = pconn->access_level;
      pconn->server.ignore_list =
          conn_pattern_list_new_full(conn_pattern_destroy);
      pconn->server.is_closing = FALSE;
      pconn->ping_time = -1.0;
      pconn->incoming_packet_notify = NULL;
      pconn->outgoing_packet_notify = NULL;
 
      sz_strlcpy(pconn->username, makeup_connection_name(&pconn->id));
      sz_strlcpy(pconn->addr, client_addr);
      sz_strlcpy(pconn->server.ipaddr, client_ip);
 
      conn_list_append(game.all_connections, pconn);
 
      log_verbose("connection (%s) from %s (%s)", 
                  pconn->username, pconn->addr, pconn->server.ipaddr);
      /* Give a ping timeout to send the PACKET_SERVER_JOIN_REQ, or close
       * the mute connection. This timer will be canceled into
       * connecthand.c:handle_login_request(). */
      timer = timer_new(TIMER_USER, TIMER_ACTIVE);
      timer_start(timer);
      timer_list_append(pconn->server.ping_timers, timer);
      return 0;
    }
  }
 
  log_error("maximum number of connections reached");
  fc_closesocket(new_sock);
  return -1;
}
 
/*************************************************************************/
int server_open_socket(void)
{
  /* setup socket address */
  union fc_sockaddr addr;
#ifdef HAVE_IP_MREQN
  struct ip_mreqn mreq4;
#else
  struct ip_mreq mreq4;
#endif
  const char *cause, *group;
  int j, on, s;
  int lan_family;
  struct fc_sockaddr_list *list;
  int name_count;
  fc_errno eno = 0;
  union fc_sockaddr *problematic = NULL;
 
#ifdef FREECIV_IPV6_SUPPORT
  struct ipv6_mreq mreq6;
#endif
 
  log_verbose("Server attempting to listen on %s:%d",
              srvarg.bind_addr ? srvarg.bind_addr : "(any)",
              srvarg.port);
 
  /* Any supported family will do */
  list = net_lookup_service(srvarg.bind_addr, srvarg.port, FC_ADDR_ANY);
 
  name_count = fc_sockaddr_list_size(list);
 
  /* Lookup addresses to bind. */
  if (name_count <= 0) {
    log_fatal(_("Server: bad address: <%s:%d>."),
              srvarg.bind_addr ? srvarg.bind_addr : "(none)", srvarg.port);
    exit(EXIT_FAILURE);
  }
 
  cause = "internal"; /* If cause is not overwritten but gets printed... */
  on = 1;
 
  /* Loop to create sockets, bind, listen. */
  listen_socks = fc_calloc(name_count, sizeof(listen_socks[0]));
  listen_count = 0;
 
  fc_sockaddr_list_iterate(list, paddr) {
    /* Create socket for client connections. */
    s = socket(paddr->saddr.sa_family, SOCK_STREAM, 0);
    if (s == -1) {
      /* Probably EAFNOSUPPORT or EPROTONOSUPPORT.
       * Kernel might have disabled AF_INET6. */
      eno = fc_get_errno();
      cause = "socket";
      problematic = paddr;
      continue;
    }
 
#ifndef FREECIV_HAVE_WINSOCK
    /* SO_REUSEADDR considered harmful on Win, necessary otherwise */
    if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, 
                   (char *)&on, sizeof(on)) == -1) {
      log_error("setsockopt SO_REUSEADDR failed: %s",
                fc_strerror(fc_get_errno()));
      sockaddr_debug(paddr, LOG_NORMAL);
    }
#endif /* FREECIV_HAVE_WINSOCK */
 
    /* AF_INET6 sockets should use IPv6 only,
     * without stealing IPv4 from AF_INET sockets. */
#ifdef FREECIV_IPV6_SUPPORT
    if (paddr->saddr.sa_family == AF_INET6) {
#ifdef IPV6_V6ONLY
      if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
                     (char *)&on, sizeof(on)) == -1) {
        log_error("setsockopt IPV6_V6ONLY failed: %s",
                  fc_strerror(fc_get_errno()));
        sockaddr_debug(paddr, LOG_DEBUG);
      }
#endif /* IPV6_V6ONLY */
    }
#endif /* IPv6 support */
 
    if (bind(s, &paddr->saddr, sockaddr_size(paddr)) == -1) {
      eno = fc_get_errno();
      cause = "bind";
      problematic = paddr;
 
      if (eno == EADDRNOTAVAIL) {
        /* Close only this socket. This address is not available.
         * This can happen with the IPv6 wildcard address if this
         * machine has no IPv6 interfaces. */
        /* If you change this logic, be sure to make clientside checking
         * of acceptable port to match. */
        fc_closesocket(s);
        continue;
      } else {
        /* Close all sockets. Another program might have bound to
         * one of our addresses, and might hijack some of our
         * connections. */
        fc_closesocket(s);
        for (j = 0; j < listen_count; j++) {
          fc_closesocket(listen_socks[j]);
        }
        listen_count = 0;
        break;
      }
    }
 
    if (listen(s, MAX_NUM_CONNECTIONS) == -1) {
      eno = fc_get_errno();
      cause = "listen";
      problematic = paddr;
      fc_closesocket(s);
      continue;
    }
 
    listen_socks[listen_count++] = s;
  } fc_sockaddr_list_iterate_end;
 
  if (listen_count == 0) {
    log_fatal("%s failure: %s (%d failed)", cause, fc_strerror(eno), name_count);
    if (problematic != NULL) {
      sockaddr_debug(problematic, LOG_NORMAL);
    }
    fc_sockaddr_list_iterate(list, paddr) {
      /* Do not list already logged 'problematic' again */
      if (paddr != problematic) {
        sockaddr_debug(paddr, LOG_DEBUG);
      }
    } fc_sockaddr_list_iterate_end;
    exit(EXIT_FAILURE);
  }
 
  fc_sockaddr_list_destroy(list);
 
  connections_set_close_callback(server_conn_close_callback);
 
  if (srvarg.announce == ANNOUNCE_NONE) {
    return 0;
  }
 
#ifdef FREECIV_IPV6_SUPPORT
  if (srvarg.announce == ANNOUNCE_IPV6) {
    lan_family = AF_INET6;
  } else
#endif /* IPV6 support */
  {
    lan_family = AF_INET;
  }
 
  /* Create socket for server LAN announcements */
  if ((socklan = socket(lan_family, SOCK_DGRAM, 0)) < 0) {
    log_error("Announcement socket failed: %s", fc_strerror(fc_get_errno()));
    return 0; /* FIXME: Should this cause hard error as exit(EXIT_FAILURE).
               *        It's failure to do as commandline parameters requested after all */
  }
 
  if (setsockopt(socklan, SOL_SOCKET, SO_REUSEADDR,
                 (char *)&on, sizeof(on)) == -1) {
    log_error("SO_REUSEADDR failed: %s", fc_strerror(fc_get_errno()));
  }
 
  fc_nonblock(socklan);
 
  group = get_multicast_group(srvarg.announce == ANNOUNCE_IPV6);
 
  memset(&addr, 0, sizeof(addr));
 
  addr.saddr.sa_family = lan_family;
 
#ifdef FREECIV_IPV6_SUPPORT
  if (addr.saddr.sa_family == AF_INET6) {
    addr.saddr_in6.sin6_family = AF_INET6;
    addr.saddr_in6.sin6_port = htons(SERVER_LAN_PORT);
    addr.saddr_in6.sin6_addr = in6addr_any;
  } else
#endif /* IPv6 support */
  if (addr.saddr.sa_family == AF_INET) {
    addr.saddr_in4.sin_family = AF_INET;
    addr.saddr_in4.sin_port = htons(SERVER_LAN_PORT);
    addr.saddr_in4.sin_addr.s_addr = htonl(INADDR_ANY);
  } else {
    fc_assert(FALSE);
 
    log_error("Unsupported address family in server_open_socket()");
  }
 
  if (bind(socklan, &addr.saddr, sockaddr_size(&addr)) < 0) {
    log_error("Announcement socket binding failed: %s", fc_strerror(fc_get_errno()));
  }
 
#ifdef FREECIV_IPV6_SUPPORT
  if (addr.saddr.sa_family == AF_INET6) {
    inet_pton(AF_INET6, group, &mreq6.ipv6mr_multiaddr.s6_addr);
    mreq6.ipv6mr_interface = 0; /* TODO: Interface selection */
    if (setsockopt(socklan, IPPROTO_IPV6, FC_IPV6_ADD_MEMBERSHIP,
                   (const char*)&mreq6, sizeof(mreq6)) < 0) {
      log_error("FC_IPV6_ADD_MEMBERSHIP (%s) failed: %s",
                group, fc_strerror(fc_get_errno()));
    }
  } else
#endif /* IPV6 Support */
  if (addr.saddr.sa_family == AF_INET) {
    fc_inet_aton(group, &mreq4.imr_multiaddr, FALSE);
#ifdef HAVE_IP_MREQN
    mreq4.imr_address.s_addr = htonl(INADDR_ANY);
    mreq4.imr_ifindex = 0;
#else
     mreq4.imr_interface.s_addr = htonl(INADDR_ANY);
#endif
 
    if (setsockopt(socklan, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                   (const char*)&mreq4, sizeof(mreq4)) < 0) {
      log_error("IP_ADD_MEMBERSHIP (%s) failed: %s",
                group, fc_strerror(fc_get_errno()));
    }
  } else {
    fc_assert(FALSE);
 
    log_error("Unsupported address family for broadcasting.");
  }
 
  return 0;
}
 
/*************************************************************************/
void init_connections(void)
{
  int i;
 
  game.all_connections = conn_list_new();
  game.est_connections = conn_list_new();
  game.glob_observers = conn_list_new();
 
  for (i = 0; i < MAX_NUM_CONNECTIONS; i++) {
    struct connection *pconn = &connections[i];
 
    pconn->used = FALSE;
    pconn->self = conn_list_new();
    conn_list_prepend(pconn->self, pconn);
  }
#if defined(__VMS)
  {
    unsigned long status;
 
    $DESCRIPTOR (tt_desc, "SYS$INPUT");
    status = sys$assign(&tt_desc, &tt_chan, 0, 0);
    if (!$VMS_STATUS_SUCCESS(status)) {
      lib$stop(status);
    }
  }
#endif /* VMS */
}
 
/*************************************************************************/
static void start_processing_request(struct connection *pconn,
                                     int request_id)
{
  fc_assert_ret(request_id);
  fc_assert_ret(pconn->server.currently_processed_request_id == 0);
  log_debug("start processing packet %d from connection %d",
            request_id, pconn->id);
  conn_compression_freeze(pconn);
  send_packet_processing_started(pconn);
  pconn->server.currently_processed_request_id = request_id;
}
 
/*************************************************************************/
static void finish_processing_request(struct connection *pconn)
{
  if (!pconn || !pconn->used) {
    return;
  }
  fc_assert_ret(pconn->server.currently_processed_request_id);
  log_debug("finish processing packet %d from connection %d",
            pconn->server.currently_processed_request_id, pconn->id);
  send_packet_processing_finished(pconn);
  pconn->server.currently_processed_request_id = 0;
  conn_compression_thaw(pconn);
}
 
/*************************************************************************/
static void connection_ping(struct connection *pconn)
{
  struct timer *timer = timer_new(TIMER_USER, TIMER_ACTIVE);
 
  log_debug("sending ping to %s (open=%d)", conn_description(pconn),
            timer_list_size(pconn->server.ping_timers));
  timer_start(timer);
  timer_list_append(pconn->server.ping_timers, timer);
  send_packet_conn_ping(pconn);
}
 
/*************************************************************************/
void handle_conn_pong(struct connection *pconn)
{
  struct timer *timer;
 
  if (timer_list_size(pconn->server.ping_timers) == 0) {
    log_error("got unexpected pong from %s", conn_description(pconn));
    return;
  }
 
  timer = timer_list_front(pconn->server.ping_timers);
  pconn->ping_time = timer_read_seconds(timer);
  timer_list_pop_front(pconn->server.ping_timers);
  log_debug("got pong from %s (open=%d); ping time = %fs",
            conn_description(pconn),
            timer_list_size(pconn->server.ping_timers), pconn->ping_time);
}
 
/*************************************************************************/
void handle_client_heartbeat(struct connection *pconn)
{
  log_debug("Received heartbeat");
}
 
/*************************************************************************/
static void send_ping_times_to_all(void)
{
  struct packet_conn_ping_info packet;
  int i;
 
  i = 0;
  conn_list_iterate(game.est_connections, pconn) {
    if (!pconn->used) {
      continue;
    }
    fc_assert(i < ARRAY_SIZE(packet.conn_id));
    packet.conn_id[i] = pconn->id;
    packet.ping_time[i] = pconn->ping_time;
    i++;
  } conn_list_iterate_end;
  packet.connections = i;
 
  lsend_packet_conn_ping_info(game.est_connections, &packet);
}
 
/*************************************************************************/
static void get_lanserver_announcement(void)
{
  fd_set readfs, exceptfs;
  fc_timeval tv;
  char msgbuf[128];
  struct data_in din;
  int type;
 
  if (srvarg.announce == ANNOUNCE_NONE) {
    return;
  }
 
  FD_ZERO(&readfs);
  FD_ZERO(&exceptfs);
  FD_SET(socklan, &exceptfs);
  FD_SET(socklan, &readfs);
 
  tv.tv_sec = 0;
  tv.tv_usec = 0;
 
  while (fc_select(socklan + 1, &readfs, NULL, &exceptfs, &tv) == -1) {
    if (errno != EINTR) {
      log_error("select failed: %s", fc_strerror(fc_get_errno()));
      return;
    }
    /* EINTR can happen sometimes, especially when compiling with -pg.
     * Generally we just want to run select again. */
  }
 
  /* We would need a raw network connection for broadcast messages */
  if (FD_ISSET(socklan, &readfs)) {
    if (0 < recvfrom(socklan, msgbuf, sizeof(msgbuf), 0, NULL, NULL)) {
      dio_input_init(&din, msgbuf, 1);
      dio_get_uint8_raw(&din, &type);
      if (type == SERVER_LAN_VERSION) {
        log_debug("Received request for server LAN announcement.");
        send_lanserver_response();
      } else {
        log_debug("Received invalid request for server LAN announcement.");
      }
    }
  }
}
 
/*************************************************************************/
/* We would need a raw network connection for broadcast messages */
static void send_lanserver_response(void)
{
#ifndef FREECIV_HAVE_WINSOCK
  unsigned char buffer[MAX_LEN_PACKET];
#else  /* FREECIV_HAVE_WINSOCK */
  char buffer[MAX_LEN_PACKET];
#endif /* FREECIV_HAVE_WINSOCK */
  char hostname[512];
  char port[256];
  char version[256];
  char players[256];
  int nhumans;
  char humans[256];
  char status[256];
  struct raw_data_out dout;
  union fc_sockaddr addr;
  int socksend, setting = 1;
  const char *group;
  size_t size;
#ifndef FREECIV_HAVE_WINSOCK
  unsigned char ttl;
#endif
  int addr_fam = addr_family_for_announce_type(srvarg.announce);
 
  /* Create a socket to broadcast to client. */
  if ((socksend = socket(addr_fam, SOCK_DGRAM, 0)) < 0) {
    log_error("Lan response socket failed: %s", fc_strerror(fc_get_errno()));
    return;
  }
 
  /* Set the UDP Multicast group IP address of the packet. */
  group = get_multicast_group(srvarg.announce == ANNOUNCE_IPV6);
  memset(&addr, 0, sizeof(addr));
#ifdef FREECIV_IPV6_SUPPORT
  if (addr_fam == AF_INET6) {
    addr.saddr_in6.sin6_family = AF_INET6;
    addr.saddr_in6.sin6_port = htons(SERVER_LAN_PORT + 1);
    inet_pton(addr_fam, group, &addr.saddr_in6.sin6_addr);
  } else
#endif /* FREECIV_IPV6_SUPPORT */
  {
    addr.saddr_in4.sin_family = AF_INET;
    addr.saddr_in4.sin_addr.s_addr = inet_addr(group);
    addr.saddr_in4.sin_port = htons(SERVER_LAN_PORT + 1);
  }
 
  /* This setsockopt call fails on Windows 98, so we stick with the default
   * value of 1 on Windows, which should be fine in most cases */
#ifndef FREECIV_HAVE_WINSOCK
  {
    int proto;
 
#ifdef FREECIV_IPV6_SUPPORT
    if (addr_fam == AF_INET6) {
      proto = IPPROTO_IPV6;
    } else
#endif /* FREECIV_IPV6_SUPPORT */
    {
      proto = IPPROTO_IP;
    }
 
    /* Set the Time-to-Live field for the packet.  */
    ttl = SERVER_LAN_TTL;
    if (setsockopt(socksend, proto, IP_MULTICAST_TTL,
                   (const char*)&ttl, sizeof(ttl))) {
      log_error("setsockopt failed: %s", fc_strerror(fc_get_errno()));
      return;
    }
  }
#endif /* FREECIV_HAVE_WINSOCK */
 
  if (setsockopt(socksend, SOL_SOCKET, SO_BROADCAST, 
                 (const char*)&setting, sizeof(setting))) {
    log_error("Lan response setsockopt failed: %s", fc_strerror(fc_get_errno()));
    return;
  }
 
  /* Create a description of server state to send to clients.  */
  if (srvarg.identity_name[0] != '\0') {
    sz_strlcpy(hostname, srvarg.identity_name);
  } else if (fc_gethostname(hostname, sizeof(hostname)) != 0) {
    sz_strlcpy(hostname, "none");
  }
 
  fc_snprintf(version, sizeof(version), "%d.%d.%d%s",
              MAJOR_VERSION, MINOR_VERSION, PATCH_VERSION, VERSION_LABEL);
 
  switch (server_state()) {
  case S_S_INITIAL:
    /* TRANS: Game state for local server */
    fc_snprintf(status, sizeof(status), _("Pregame"));
    break;
  case S_S_RUNNING:
    /* TRANS: Game state for local server */
    fc_snprintf(status, sizeof(status), _("Running"));
    break;
  case S_S_OVER:
    /* TRANS: Game state for local server */
    fc_snprintf(status, sizeof(status), _("Game over"));
    break;
  }
 
  fc_snprintf(players, sizeof(players), "%d",
              normal_player_count());
 
  nhumans = 0;
  players_iterate(pplayer) {
    if (pplayer->is_alive && is_human(pplayer)) {
      nhumans++;
    }
  } players_iterate_end;
  fc_snprintf(humans, sizeof(humans), "%d", nhumans);
 
  fc_snprintf(port, sizeof(port), "%d",
              srvarg.port);
 
  dio_output_init(&dout, buffer, sizeof(buffer));
  dio_put_uint8_raw(&dout, SERVER_LAN_VERSION);
  dio_put_string_raw(&dout, hostname);
  dio_put_string_raw(&dout, port);
  dio_put_string_raw(&dout, version);
  dio_put_string_raw(&dout, status);
  dio_put_string_raw(&dout, players);
  dio_put_string_raw(&dout, humans);
  dio_put_string_raw(&dout, get_meta_message_string());
  size = dio_output_used(&dout);
 
  /* Sending packet to client with the information gathered above. */
  if (sendto(socksend, buffer,  size, 0, &addr.saddr,
      sockaddr_size(&addr)) < 0) {
    log_error("landserver response sendto failed: %s",
              fc_strerror(fc_get_errno()));
    return;
  }
 
  fc_closesocket(socksend);
}