servers.c

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/***********************************************************************
 Freeciv - Copyright (C) 1996-2005 - Freeciv Development Team
   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 <stdlib.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 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
 
/* dependencies */
#include "cvercmp.h"
 
/* utility */
#include "fcintl.h"
#include "fcthread.h"
#include "log.h"
#include "mem.h"
#include "netfile.h"
#include "netintf.h"
#include "rand.h" /* fc_rand() */
#include "registry.h"
#include "support.h"
 
/* common */
#include "capstr.h"
#include "dataio.h"
#include "game.h"
#include "packets.h"
#include "version.h"
 
/* client */
#include "chatline_common.h"
#include "chatline_g.h"
#include "client_main.h"
#include "options.h"
#include "servers.h"
 
#include "gui_main_g.h"
 
struct server_scan {
  enum server_scan_type type;
  ServerScanErrorFunc error_func;
 
  struct srv_list srvrs;
  int sock;
 
#ifdef FREECIV_META_ENABLED
  /* Only used for metaserver */
  struct {
    enum server_scan_status status;
 
    fc_thread thr;
    fc_mutex mutex;
 
    const char *urlpath;
    struct netfile_write_cb_data mem;
  } meta;
#endif /* FREECIV_META_ENABLED */
};
 
extern enum announce_type announce;
 
static void delete_server_list(struct server_list *server_list);
 
#ifdef FREECIV_META_ENABLED
static bool begin_metaserver_scan(struct server_scan *scan);
 
/**********************************************************************/
static struct server_list *parse_metaserver_data(fz_FILE *f)
{
  struct server_list *server_list;
  struct section_file *file;
  int nservers, i, j;
  const char *latest_ver;
  const char *comment;
  char *followtag;
  char *q_followtag;
 
  /* Have the string outside Q_() so it won't get collected for translation here.
   * Actual collected string lives in translations/Strings.txt */
#define QUALIFIED_FOLLOWTAG "?vertag:" FOLLOWTAG
 
  /* This call closes f. */
  if (!(file = secfile_from_stream(f, TRUE))) {
    return NULL;
  }
 
  if (fc_strcasecmp(DEFAULT_FOLLOWTAG_OPTION, gui_options.followtag_override)) {
    followtag = gui_options.followtag_override;
    q_followtag = gui_options.followtag_override;
  } else {
    followtag = FOLLOWTAG;
    q_followtag = QUALIFIED_FOLLOWTAG;
  }
 
  latest_ver = secfile_lookup_str_default(file, NULL, "versions.%s", followtag);
  comment = secfile_lookup_str_default(file, NULL, "version_comments.%s", followtag);
 
  if (latest_ver == NULL && comment == NULL) {
    char vertext[2048];
 
    fc_snprintf(vertext, sizeof(vertext),
                /* TRANS: Type is version tag name like "stable", "S3_2",
                 * "windows" (which can also be localised -- msgids start
                 * '?vertag:') */
                _("There's no %s release yet."), Q_(q_followtag));
    log_verbose("%s", vertext);
    version_message(vertext);
  } else {
    if (latest_ver != NULL) {
      const char *my_comparable = fc_comparable_version();
      char vertext[2048];
 
      log_verbose("Metaserver says latest '%s' version is '%s'; we have '%s'",
                  followtag, latest_ver, my_comparable);
      if (cvercmp_greater(latest_ver, my_comparable)) {
 
        fc_snprintf(vertext, sizeof(vertext),
                    /* TRANS: Type is version tag name like "stable", "S3_2",
                     * "windows" (which can also be localised -- msgids start
                     * '?vertag:') */
                    _("Latest %s release of Freeciv is %s, this is %s."),
                    Q_(q_followtag), latest_ver, my_comparable);
 
        version_message(vertext);
      } else if (comment == NULL) {
        fc_snprintf(vertext, sizeof(vertext),
                    _("There is no newer %s release of Freeciv available."),
                    followtag);
 
        version_message(vertext);
      }
    }
 
    if (comment != NULL) {
      log_verbose("Mesaserver comment about '%s': %s", followtag, comment);
      version_message(comment);
    }
  }
 
  server_list = server_list_new();
  nservers = secfile_lookup_int_default(file, 0, "main.nservers");
 
  for (i = 0; i < nservers; i++) {
    const char *host, *port, *version, *state, *message, *nplayers, *nhumans;
    int n;
    struct server *pserver = (struct server*)fc_malloc(sizeof(struct server));
 
    host = secfile_lookup_str_default(file, "", "server%d.host", i);
    pserver->host = fc_strdup(host);
 
    port = secfile_lookup_str_default(file, "", "server%d.port", i);
    pserver->port = atoi(port);
 
    version = secfile_lookup_str_default(file, "", "server%d.version", i);
    pserver->version = fc_strdup(version);
 
    state = secfile_lookup_str_default(file, "", "server%d.state", i);
    pserver->state = fc_strdup(state);
 
    message = secfile_lookup_str_default(file, "", "server%d.message", i);
    pserver->message = fc_strdup(message);
 
    nplayers = secfile_lookup_str_default(file, "0", "server%d.nplayers", i);
    n = atoi(nplayers);
    pserver->nplayers = n;
 
    nhumans = secfile_lookup_str_default(file, "-1", "server%d.humans", i);
    n = atoi(nhumans);
    pserver->humans = n;
 
    if (pserver->nplayers > 0) {
      pserver->players = fc_malloc(pserver->nplayers * sizeof(*pserver->players));
    } else {
      pserver->players = NULL;
    }
 
    for (j = 0; j < pserver->nplayers ; j++) {
      const char *name, *nation, *type, *plrhost;
 
      name = secfile_lookup_str_default(file, "", 
                                        "server%d.player%d.name", i, j);
      pserver->players[j].name = fc_strdup(name);
 
      type = secfile_lookup_str_default(file, "",
                                        "server%d.player%d.type", i, j);
      pserver->players[j].type = fc_strdup(type);
 
      plrhost = secfile_lookup_str_default(file, "", 
                                           "server%d.player%d.host", i, j);
      pserver->players[j].host = fc_strdup(plrhost);
 
      nation = secfile_lookup_str_default(file, "",
                                          "server%d.player%d.nation", i, j);
      pserver->players[j].nation = fc_strdup(nation);
    }
 
    server_list_append(server_list, pserver);
  }
 
  secfile_destroy(file);
 
  return server_list;
}
 
/**********************************************************************/
static bool meta_read_response(struct server_scan *scan)
{
  fz_FILE *f;
  char str[4096];
  struct server_list *srvrs;
 
  f = fz_from_memory(scan->meta.mem.mem, scan->meta.mem.size, TRUE);
  if (NULL == f) {
    fc_snprintf(str, sizeof(str),
                _("Failed to read the metaserver data from %s."),
                metaserver);
    scan->error_func(scan, str);
 
    return FALSE;
  }
 
  /* Parse message body */
  fc_mutex_allocate(&scan->srvrs.mutex);
  srvrs = parse_metaserver_data(f);
  scan->srvrs.servers = srvrs;
  fc_mutex_release(&scan->srvrs.mutex);
 
  /* 'f' (hence 'meta.mem.mem') was closed in parse_metaserver_data(). */
  scan->meta.mem.mem = NULL;
 
  if (NULL == srvrs) {
    fc_snprintf(str, sizeof(str),
                _("Failed to parse the metaserver data from %s:\n"
                  "%s."),
                metaserver, secfile_error());
    scan->error_func(scan, str);
 
    return FALSE;
  }
 
  return TRUE;
}
 
/**********************************************************************/
static void metaserver_scan(void *arg)
{
  struct server_scan *scan = arg;
 
  if (!begin_metaserver_scan(scan)) {
    fc_mutex_allocate(&scan->meta.mutex);
    scan->meta.status = SCAN_STATUS_ERROR;
  } else {
    if (!meta_read_response(scan)) {
      fc_mutex_allocate(&scan->meta.mutex);
      scan->meta.status = SCAN_STATUS_ERROR;
    } else {
      fc_mutex_allocate(&scan->meta.mutex);
      if (scan->meta.status == SCAN_STATUS_WAITING) {
        scan->meta.status = SCAN_STATUS_DONE;
      }
    }
  }
 
  fc_mutex_release(&scan->meta.mutex);
}
 
/**********************************************************************/
static bool begin_metaserver_scan(struct server_scan *scan)
{
  struct netfile_post *post;
  bool retval = TRUE;
 
  post = netfile_start_post();
  netfile_add_form_str(post, "client_cap", our_capability);
 
  if (!netfile_send_post(metaserver, post, NULL, &scan->meta.mem, NULL)) {
    scan->error_func(scan, _("Error connecting to metaserver"));
    retval = FALSE;
  }
 
  netfile_close_post(post);
 
  return retval;
}
#endif /* FREECIV_META_ENABLED */
 
/**********************************************************************/
static void delete_server_list(struct server_list *server_list)
{
  if (!server_list) {
    return;
  }
 
  server_list_iterate(server_list, ptmp) {
    int i;
    int n = ptmp->nplayers;
 
    free(ptmp->host);
    free(ptmp->version);
    free(ptmp->state);
    free(ptmp->message);
 
    if (ptmp->players) {
      for (i = 0; i < n; i++) {
        free(ptmp->players[i].name);
        free(ptmp->players[i].type);
        free(ptmp->players[i].host);
        free(ptmp->players[i].nation);
      }
      free(ptmp->players);
    }
 
    free(ptmp);
  } server_list_iterate_end;
 
  server_list_destroy(server_list);
}
 
/**********************************************************************/
static bool begin_lanserver_scan(struct server_scan *scan)
{
  union fc_sockaddr addr;
  struct raw_data_out dout;
  int send_sock, opt = 1;
#ifndef FREECIV_HAVE_WINSOCK
  unsigned char buffer[MAX_LEN_PACKET];
#else  /* FREECIV_HAVE_WINSOCK */
  char buffer[MAX_LEN_PACKET];
#endif /* FREECIV_HAVE_WINSOCK */
#ifdef HAVE_IP_MREQN
  struct ip_mreqn mreq4;
#else
  struct ip_mreq mreq4;
#endif
  const char *group;
  size_t size;
  int family;
 
#ifdef FREECIV_IPV6_SUPPORT
  struct ipv6_mreq mreq6;
#endif
 
#ifndef FREECIV_HAVE_WINSOCK
  unsigned char ttl;
#endif
 
  if (announce == ANNOUNCE_NONE) {
    /* Succeeded in doing nothing */
    return TRUE;
  }
 
#ifdef FREECIV_IPV6_SUPPORT
  if (announce == ANNOUNCE_IPV6) {
    family = AF_INET6;
  } else
#endif /* IPv6 support */
  {
    family = AF_INET;
  }
 
  /* Set the UDP Multicast group IP address. */
  group = get_multicast_group(announce == ANNOUNCE_IPV6);
 
  /* Create a socket for listening for server packets. */
  if ((scan->sock = socket(family, SOCK_DGRAM, 0)) < 0) {
    char errstr[2048];
 
    fc_snprintf(errstr, sizeof(errstr),
                _("Opening socket to listen LAN announcements failed:\n%s"),
                fc_strerror(fc_get_errno()));
    scan->error_func(scan, errstr);
 
    return FALSE;
  }
 
  fc_nonblock(scan->sock);
 
  if (setsockopt(scan->sock, SOL_SOCKET, SO_REUSEADDR,
                 (char *)&opt, sizeof(opt)) == -1) {
    log_error("SO_REUSEADDR failed: %s", fc_strerror(fc_get_errno()));
  }
 
  memset(&addr, 0, sizeof(addr));
 
#ifdef FREECIV_IPV6_SUPPORT
  if (family == AF_INET6) {
    addr.saddr.sa_family = AF_INET6;
    addr.saddr_in6.sin6_port = htons(SERVER_LAN_PORT + 1);
    addr.saddr_in6.sin6_addr = in6addr_any;
  } else
#endif /* IPv6 support */
  if (family == AF_INET) {
    addr.saddr.sa_family = AF_INET;
    addr.saddr_in4.sin_port = htons(SERVER_LAN_PORT + 1);
    addr.saddr_in4.sin_addr.s_addr = htonl(INADDR_ANY);
  } else {
    /* This is not only error situation worth assert() This
     * is error situation that has check (with assert) against
     * earlier already. */
    fc_assert(FALSE);
 
    return FALSE;
  }
 
  if (bind(scan->sock, &addr.saddr, sockaddr_size(&addr)) < 0) {
    char errstr[2048];
 
    fc_snprintf(errstr, sizeof(errstr),
                _("Binding socket to listen LAN announcements failed:\n%s"),
                fc_strerror(fc_get_errno()));
    scan->error_func(scan, errstr);
 
    return FALSE;
  }
 
#ifdef FREECIV_IPV6_SUPPORT
  if (family == AF_INET6) {
    inet_pton(AF_INET6, group, &mreq6.ipv6mr_multiaddr.s6_addr);
    mreq6.ipv6mr_interface = 0; /* TODO: Interface selection */
 
    if (setsockopt(scan->sock, IPPROTO_IPV6, FC_IPV6_ADD_MEMBERSHIP,
                   (const char*)&mreq6, sizeof(mreq6)) < 0) {
      char errstr[2048];
 
      fc_snprintf(errstr, sizeof(errstr),
                  _("Adding membership for IPv6 LAN announcement group failed:\n%s"),
                fc_strerror(fc_get_errno()));
      scan->error_func(scan, errstr);
    }
  } else
#endif /* IPv6 support */
  {
    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(scan->sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                   (const char*)&mreq4, sizeof(mreq4)) < 0) {
      char errstr[2048];
 
      fc_snprintf(errstr, sizeof(errstr),
                  _("Adding membership for IPv4 LAN announcement group failed:\n%s"),
                  fc_strerror(fc_get_errno()));
      scan->error_func(scan, errstr);
 
      return FALSE;
    }
  }
 
  /* Create a socket for broadcasting to servers. */
  if ((send_sock = socket(family, SOCK_DGRAM, 0)) < 0) {
    char errstr[2048];
 
    fc_snprintf(errstr, sizeof(errstr),
                _("Opening socket for sending LAN announcement request failed:\n%s"),
                fc_strerror(fc_get_errno()));
    scan->error_func(scan, errstr);
 
    return FALSE;
  }
 
  memset(&addr, 0, sizeof(addr));
 
#ifdef FREECIV_IPV6_SUPPORT
  if (family == AF_INET6) {
    addr.saddr.sa_family = AF_INET6;
    inet_pton(AF_INET6, group, &addr.saddr_in6.sin6_addr);
    addr.saddr_in6.sin6_port = htons(SERVER_LAN_PORT);
  } else
#endif /* IPv6 Support */
  if (family == AF_INET) {
    fc_inet_aton(group, &addr.saddr_in4.sin_addr, FALSE);
    addr.saddr.sa_family = AF_INET;
    addr.saddr_in4.sin_port = htons(SERVER_LAN_PORT);
  } else {
    fc_assert(FALSE);
 
    log_error("Unsupported address family in begin_lanserver_scan()");
 
    return FALSE;
  }
 
/* 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
  /* Set the Time-to-Live field for the packet  */
  ttl = SERVER_LAN_TTL;
  if (setsockopt(send_sock, IPPROTO_IP, IP_MULTICAST_TTL, (const char*)&ttl, 
                 sizeof(ttl))) {
    char errstr[2048];
 
    fc_snprintf(errstr, sizeof(errstr),
                _("Setting Time-to-Live failed:\n%s"),
                fc_strerror(fc_get_errno()));
    scan->error_func(scan, errstr);
 
    /* FIXME: Is this really supposed to be an hard error, or should we
     *        just continue? After all, Windows builds do not even attempt this. */
    return FALSE;
  }
#endif /* FREECIV_HAVE_WINSOCK */
 
  if (setsockopt(send_sock, SOL_SOCKET, SO_BROADCAST, (const char*)&opt, 
                 sizeof(opt))) {
    char errstr[2048];
 
    fc_snprintf(errstr, sizeof(errstr),
                _("Setting Broadcast option failed:\n%s"),
                fc_strerror(fc_get_errno()));
    scan->error_func(scan, errstr);
 
    return FALSE;
  }
 
  dio_output_init(&dout, buffer, sizeof(buffer));
  dio_put_uint8_raw(&dout, SERVER_LAN_VERSION);
  size = dio_output_used(&dout);
 
 
  if (sendto(send_sock, buffer, size, 0, &addr.saddr,
             sockaddr_size(&addr)) < 0) {
    /* This can happen when there's no network connection */
    char errstr[2048];
 
    fc_snprintf(errstr, sizeof(errstr),
                _("Sending LAN announcement request failed:\n%s"),
                fc_strerror(fc_get_errno()));
    scan->error_func(scan, errstr);
 
    return FALSE;
  } else {
    log_debug("Sending request for server announcement on LAN.");
  }
 
  fc_closesocket(send_sock);
 
  fc_mutex_allocate(&scan->srvrs.mutex);
  scan->srvrs.servers = server_list_new();
  fc_mutex_release(&scan->srvrs.mutex);
 
  return TRUE;
}
 
/**********************************************************************/
static enum server_scan_status
get_lan_server_list(struct server_scan *scan)
{
  socklen_t fromlen;
  union fc_sockaddr fromend;
  char msgbuf[128];
  int type;
  struct data_in din;
  char servername[512];
  char portstr[256];
  int port;
  char version[256];
  char status[256];
  char players[256];
  char humans[256];
  char message[1024];
  bool found_new = FALSE;
 
  while (TRUE) {
    struct server *pserver;
    bool duplicate = FALSE;
 
    dio_input_init(&din, msgbuf, sizeof(msgbuf));
    fromlen = sizeof(fromend);
 
    /* Try to receive a packet from a server.  No select loop is needed;
     * we just keep on reading until recvfrom returns -1. */
    if (recvfrom(scan->sock, msgbuf, sizeof(msgbuf), 0,
                 &fromend.saddr, &fromlen) < 0) {
      break;
    }
 
    dio_get_uint8_raw(&din, &type);
    if (type != SERVER_LAN_VERSION) {
      continue;
    }
    dio_get_string_raw(&din, servername, sizeof(servername));
    dio_get_string_raw(&din, portstr, sizeof(portstr));
    port = atoi(portstr);
    dio_get_string_raw(&din, version, sizeof(version));
    dio_get_string_raw(&din, status, sizeof(status));
    dio_get_string_raw(&din, players, sizeof(players));
    dio_get_string_raw(&din, humans, sizeof(humans));
    dio_get_string_raw(&din, message, sizeof(message));
 
    if (!fc_strcasecmp("none", servername)) {
      bool nameinfo = FALSE;
#ifdef FREECIV_IPV6_SUPPORT
      char dst[INET6_ADDRSTRLEN];
      char host[NI_MAXHOST], service[NI_MAXSERV];
 
      if (!getnameinfo(&fromend.saddr, fromlen, host, NI_MAXHOST,
                       service, NI_MAXSERV, NI_NUMERICSERV)) {
        nameinfo = TRUE;
      }
      if (!nameinfo) {
        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 get_lan_server_list()");
 
          fc_snprintf(dst, sizeof(dst), "Unknown");
        }
      }
#else  /* IPv6 support */
      const char *dst = NULL;
      struct hostent *from;
      const char *host = NULL;
 
      from = gethostbyaddr((char *) &fromend.saddr_in4.sin_addr,
                           sizeof(fromend.saddr_in4.sin_addr), AF_INET);
      if (from) {
        host = from->h_name;
        nameinfo = TRUE;
      }
      if (!nameinfo) {
        dst = inet_ntoa(fromend.saddr_in4.sin_addr);
      }
#endif /* IPv6 support */
 
      sz_strlcpy(servername, nameinfo ? host : dst);
    }
 
    /* UDP can send duplicate or delayed packets. */
    fc_mutex_allocate(&scan->srvrs.mutex);
    server_list_iterate(scan->srvrs.servers, aserver) {
      if (0 == fc_strcasecmp(aserver->host, servername)
          && aserver->port == port) {
        duplicate = TRUE;
        break;
      }
    } server_list_iterate_end;
 
    if (duplicate) {
      fc_mutex_release(&scan->srvrs.mutex);
      continue;
    }
 
    log_debug("Received a valid announcement from a server on the LAN.");
 
    pserver = fc_malloc(sizeof(*pserver));
    pserver->host = fc_strdup(servername);
    pserver->port = port;
    pserver->version = fc_strdup(version);
    pserver->state = fc_strdup(status);
    pserver->nplayers = atoi(players);
    pserver->humans = atoi(humans);
    pserver->message = fc_strdup(message);
    pserver->players = NULL;
    found_new = TRUE;
 
    server_list_prepend(scan->srvrs.servers, pserver);
    fc_mutex_release(&scan->srvrs.mutex);
  }
 
  if (found_new) {
    return SCAN_STATUS_PARTIAL;
  }
  return SCAN_STATUS_WAITING;
}
 
/**********************************************************************/
struct server_scan *server_scan_begin(enum server_scan_type type,
                                      ServerScanErrorFunc error_func)
{
  struct server_scan *scan;
  bool ok = FALSE;
 
#ifndef FREECIV_META_ENABLED
  if (type == SERVER_SCAN_GLOBAL) {
    return NULL;
  }
#endif /* FREECIV_META_ENABLED */
 
  scan = fc_calloc(1, sizeof(*scan));
  scan->type = type;
  scan->error_func = error_func;
  scan->sock = -1;
  fc_mutex_init(&scan->srvrs.mutex);
 
  switch (type) {
  case SERVER_SCAN_GLOBAL:
    {
#ifdef FREECIV_META_ENABLED
      int thr_ret;
 
      fc_mutex_init(&scan->meta.mutex);
      scan->meta.status = SCAN_STATUS_WAITING;
      thr_ret = fc_thread_start(&scan->meta.thr, metaserver_scan, scan);
      if (thr_ret) {
        ok = FALSE;
      } else {
        ok = TRUE;
      }
#endif /* FREECIV_META_ENABLED */
    }
    break;
  case SERVER_SCAN_LOCAL:
    ok = begin_lanserver_scan(scan);
    break;
  case SERVER_SCAN_LAST:
    break;
  }
 
  if (!ok) {
    server_scan_finish(scan);
    scan = NULL;
  }
 
  return scan;
}
 
/**********************************************************************/
enum server_scan_type server_scan_get_type(const struct server_scan *scan)
{
  if (!scan) {
    return SERVER_SCAN_LAST;
  }
  return scan->type;
}
 
/**********************************************************************/
enum server_scan_status server_scan_poll(struct server_scan *scan)
{
  if (!scan) {
    return SCAN_STATUS_ERROR;
  }
 
  switch (scan->type) {
  case SERVER_SCAN_GLOBAL:
#ifdef FREECIV_META_ENABLED
    {
      enum server_scan_status status;
 
      fc_mutex_allocate(&scan->meta.mutex);
      status = scan->meta.status;
      fc_mutex_release(&scan->meta.mutex);
 
      return status;
    }
#endif /* FREECIV_META_ENABLED */
    break;
  case SERVER_SCAN_LOCAL:
    return get_lan_server_list(scan);
    break;
  case SERVER_SCAN_LAST:
    break;
  }
 
  return SCAN_STATUS_ERROR;
}
 
/**********************************************************************/
struct srv_list *
server_scan_get_list(struct server_scan *scan)
{
  if (!scan) {
    return NULL;
  }
 
  return &scan->srvrs;
}
 
/**********************************************************************/
void server_scan_finish(struct server_scan *scan)
{
  if (!scan) {
    return;
  }
 
  if (scan->type == SERVER_SCAN_GLOBAL) {
#ifdef FREECIV_META_ENABLED
    /* Signal metaserver scan thread to stop */
    fc_mutex_allocate(&scan->meta.mutex);
    scan->meta.status = SCAN_STATUS_ABORT;
    fc_mutex_release(&scan->meta.mutex);
 
    /* Wait thread to stop */
    fc_thread_wait(&scan->meta.thr);
    fc_mutex_destroy(&scan->meta.mutex);
 
    /* This mainly duplicates code from below "else" block.
     * That's intentional, since they will be completely different in future versions.
     * We are better prepared for that by having them separately already. */
    if (scan->sock >= 0) {
      fc_closesocket(scan->sock);
      scan->sock = -1;
    }
 
    if (scan->srvrs.servers) {
      fc_mutex_allocate(&scan->srvrs.mutex);
      delete_server_list(scan->srvrs.servers);
      scan->srvrs.servers = NULL;
      fc_mutex_release(&scan->srvrs.mutex);
    }
 
    if (scan->meta.mem.mem) {
      FC_FREE(scan->meta.mem.mem);
      scan->meta.mem.mem = NULL;
    }
#endif /* FREECIV_META_ENABLED */
  } else {
    if (scan->sock >= 0) {
      fc_closesocket(scan->sock);
      scan->sock = -1;
    }
 
    if (scan->srvrs.servers) {
      delete_server_list(scan->srvrs.servers);
      scan->srvrs.servers = NULL;
    }
  }
 
  fc_mutex_destroy(&scan->srvrs.mutex);
 
  free(scan);
}