/*
     This file is part of GNUnet.
     (C) 2009 Christian Grothoff (and other contributing authors)

     GNUnet 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.

     GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file util/service.c
 * @brief functions related to starting services
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_common.h"
#include "gnunet_configuration_lib.h"
#include "gnunet_crypto_lib.h"
#include "gnunet_directories.h"
#include "gnunet_disk_lib.h"
#include "gnunet_getopt_lib.h"
#include "gnunet_os_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_resolver_service.h"
#include "gnunet_server_lib.h"
#include "gnunet_service_lib.h"

#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)

#define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util", syscall)

#define LOG_STRERROR_FILE(kind,syscall,filename) GNUNET_log_from_strerror_file (kind, "util", syscall, filename)

#define DEBUG_SERVICE GNUNET_EXTRA_LOGGING

/* ******************* access control ******************** */

/**
 * @brief IPV4 network in CIDR notation.
 */
struct IPv4NetworkSet
{
  struct in_addr network;
  struct in_addr netmask;
};

/**
 * @brief network in CIDR notation for IPV6.
 */
struct IPv6NetworkSet
{
  struct in6_addr network;
  struct in6_addr netmask;
};


/**
 * Parse a network specification. The argument specifies
 * a list of networks. The format is
 * <tt>[network/netmask;]*</tt> (no whitespace, must be terminated
 * with a semicolon). The network must be given in dotted-decimal
 * notation. The netmask can be given in CIDR notation (/16) or
 * in dotted-decimal (/255.255.0.0).
 * <p>
 * @param routeList a string specifying the forbidden networks
 * @return the converted list, NULL if the synatx is flawed
 */
static struct IPv4NetworkSet *
parse_ipv4_specification (const char *routeList)
{
  unsigned int count;
  unsigned int i;
  unsigned int j;
  unsigned int len;
  int cnt;
  unsigned int pos;
  unsigned int temps[8];
  int slash;
  struct IPv4NetworkSet *result;

  if (routeList == NULL)
    return NULL;
  len = strlen (routeList);
  if (len == 0)
    return NULL;
  count = 0;
  for (i = 0; i < len; i++)
    if (routeList[i] == ';')
      count++;
  result = GNUNET_malloc (sizeof (struct IPv4NetworkSet) * (count + 1));
  /* add termination */
  memset (result, 0, sizeof (struct IPv4NetworkSet) * (count + 1));
  i = 0;
  pos = 0;
  while (i < count)
  {
    cnt =
        sscanf (&routeList[pos], "%u.%u.%u.%u/%u.%u.%u.%u;", &temps[0],
                &temps[1], &temps[2], &temps[3], &temps[4], &temps[5],
                &temps[6], &temps[7]);
    if (cnt == 8)
    {
      for (j = 0; j < 8; j++)
        if (temps[j] > 0xFF)
        {
          LOG (GNUNET_ERROR_TYPE_ERROR, _("Invalid format for IP: `%s'\n"),
               &routeList[pos]);
          GNUNET_free (result);
          return NULL;
        }
      result[i].network.s_addr =
          htonl ((temps[0] << 24) + (temps[1] << 16) + (temps[2] << 8) +
                 temps[3]);
      result[i].netmask.s_addr =
          htonl ((temps[4] << 24) + (temps[5] << 16) + (temps[6] << 8) +
                 temps[7]);
      while (routeList[pos] != ';')
        pos++;
      pos++;
      i++;
      continue;
    }
    /* try second notation */
    cnt =
        sscanf (&routeList[pos], "%u.%u.%u.%u/%u;", &temps[0], &temps[1],
                &temps[2], &temps[3], &slash);
    if (cnt == 5)
    {
      for (j = 0; j < 4; j++)
        if (temps[j] > 0xFF)
        {
          LOG (GNUNET_ERROR_TYPE_ERROR, _("Invalid format for IP: `%s'\n"),
               &routeList[pos]);
          GNUNET_free (result);
          return NULL;
        }
      result[i].network.s_addr =
          htonl ((temps[0] << 24) + (temps[1] << 16) + (temps[2] << 8) +
                 temps[3]);
      if ((slash <= 32) && (slash >= 0))
      {
        result[i].netmask.s_addr = 0;
        while (slash > 0)
        {
          result[i].netmask.s_addr =
              (result[i].netmask.s_addr >> 1) + 0x80000000;
          slash--;
        }
        result[i].netmask.s_addr = htonl (result[i].netmask.s_addr);
        while (routeList[pos] != ';')
          pos++;
        pos++;
        i++;
        continue;
      }
      else
      {
        LOG (GNUNET_ERROR_TYPE_ERROR,
             _("Invalid network notation ('/%d' is not legal in IPv4 CIDR)."),
             slash);
        GNUNET_free (result);
        return NULL;            /* error */
      }
    }
    /* try third notation */
    slash = 32;
    cnt =
        sscanf (&routeList[pos], "%u.%u.%u.%u;", &temps[0], &temps[1],
                &temps[2], &temps[3]);
    if (cnt == 4)
    {
      for (j = 0; j < 4; j++)
        if (temps[j] > 0xFF)
        {
          LOG (GNUNET_ERROR_TYPE_ERROR, _("Invalid format for IP: `%s'\n"),
               &routeList[pos]);
          GNUNET_free (result);
          return NULL;
        }
      result[i].network.s_addr =
          htonl ((temps[0] << 24) + (temps[1] << 16) + (temps[2] << 8) +
                 temps[3]);
      result[i].netmask.s_addr = 0;
      while (slash > 0)
      {
        result[i].netmask.s_addr = (result[i].netmask.s_addr >> 1) + 0x80000000;
        slash--;
      }
      result[i].netmask.s_addr = htonl (result[i].netmask.s_addr);
      while (routeList[pos] != ';')
        pos++;
      pos++;
      i++;
      continue;
    }
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Invalid format for IP: `%s'\n"),
         &routeList[pos]);
    GNUNET_free (result);
    return NULL;                /* error */
  }
  if (pos < strlen (routeList))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Invalid format for IP: `%s'\n"),
         &routeList[pos]);
    GNUNET_free (result);
    return NULL;                /* oops */
  }
  return result;                /* ok */
}


/**
 * Parse a network specification. The argument specifies
 * a list of networks. The format is
 * <tt>[network/netmask;]*</tt> (no whitespace, must be terminated
 * with a semicolon). The network must be given in colon-hex
 * notation.  The netmask must be given in CIDR notation (/16) or
 * can be omitted to specify a single host.
 * <p>
 * @param routeListX a string specifying the forbidden networks
 * @return the converted list, NULL if the synatx is flawed
 */
static struct IPv6NetworkSet *
parse_ipv6_specification (const char *routeListX)
{
  unsigned int count;
  unsigned int i;
  unsigned int len;
  unsigned int pos;
  int start;
  int slash;
  int ret;
  char *routeList;
  struct IPv6NetworkSet *result;
  unsigned int bits;
  unsigned int off;
  int save;

  if (routeListX == NULL)
    return NULL;
  len = strlen (routeListX);
  if (len == 0)
    return NULL;
  routeList = GNUNET_strdup (routeListX);
  count = 0;
  for (i = 0; i < len; i++)
    if (routeList[i] == ';')
      count++;
  if (routeList[len - 1] != ';')
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _("Invalid network notation (does not end with ';': `%s')\n"),
         routeList);
    GNUNET_free (routeList);
    return NULL;
  }

  result = GNUNET_malloc (sizeof (struct IPv6NetworkSet) * (count + 1));
  memset (result, 0, sizeof (struct IPv6NetworkSet) * (count + 1));
  i = 0;
  pos = 0;
  while (i < count)
  {
    start = pos;
    while (routeList[pos] != ';')
      pos++;
    slash = pos;
    while ((slash >= start) && (routeList[slash] != '/'))
      slash--;
    if (slash < start)
    {
      memset (&result[i].netmask, 0xFF, sizeof (struct in6_addr));
      slash = pos;
    }
    else
    {
      routeList[pos] = '\0';
      ret = inet_pton (AF_INET6, &routeList[slash + 1], &result[i].netmask);
      if (ret <= 0)
      {
        save = errno;
        if ((1 != SSCANF (&routeList[slash + 1], "%u", &bits)) || (bits >= 128))
        {
          if (ret == 0)
            LOG (GNUNET_ERROR_TYPE_ERROR, _("Wrong format `%s' for netmask\n"),
                 &routeList[slash + 1]);
          else
          {
            errno = save;
            LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "inet_pton");
          }
          GNUNET_free (result);
          GNUNET_free (routeList);
          return NULL;
        }
        off = 0;
        while (bits > 8)
        {
          result[i].netmask.s6_addr[off++] = 0xFF;
          bits -= 8;
        }
        while (bits > 0)
        {
          result[i].netmask.s6_addr[off] =
              (result[i].netmask.s6_addr[off] >> 1) + 0x80;
          bits--;
        }
      }
    }
    routeList[slash] = '\0';
    ret = inet_pton (AF_INET6, &routeList[start], &result[i].network);
    if (ret <= 0)
    {
      if (ret == 0)
        LOG (GNUNET_ERROR_TYPE_ERROR, _("Wrong format `%s' for network\n"),
             &routeList[slash + 1]);
      else
        LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "inet_pton");
      GNUNET_free (result);
      GNUNET_free (routeList);
      return NULL;
    }
    pos++;
    i++;
  }
  GNUNET_free (routeList);
  return result;
}


/**
 * Check if the given IP address is in the list of IP addresses.
 *
 * @param list a list of networks
 * @param add the IP to check (in network byte order)
 * @return GNUNET_NO if the IP is not in the list, GNUNET_YES if it it is
 */
static int
check_ipv4_listed (const struct IPv4NetworkSet *list, const struct in_addr *add)
{
  int i;

  i = 0;
  if (list == NULL)
    return GNUNET_NO;

  while ((list[i].network.s_addr != 0) || (list[i].netmask.s_addr != 0))
  {
    if ((add->s_addr & list[i].netmask.s_addr) ==
        (list[i].network.s_addr & list[i].netmask.s_addr))
      return GNUNET_YES;
    i++;
  }
  return GNUNET_NO;
}

/**
 * Check if the given IP address is in the list of IP addresses.
 *
 * @param list a list of networks
 * @param ip the IP to check (in network byte order)
 * @return GNUNET_NO if the IP is not in the list, GNUNET_YES if it it is
 */
static int
check_ipv6_listed (const struct IPv6NetworkSet *list, const struct in6_addr *ip)
{
  unsigned int i;
  unsigned int j;
  struct in6_addr zero;

  if (list == NULL)
    return GNUNET_NO;

  memset (&zero, 0, sizeof (struct in6_addr));
  i = 0;
NEXT:
  while (memcmp (&zero, &list[i].network, sizeof (struct in6_addr)) != 0)
  {
    for (j = 0; j < sizeof (struct in6_addr) / sizeof (int); j++)
      if (((((int *) ip)[j] & ((int *) &list[i].netmask)[j])) !=
          (((int *) &list[i].network)[j] & ((int *) &list[i].netmask)[j]))
      {
        i++;
        goto NEXT;
      }
    return GNUNET_YES;
  }
  return GNUNET_NO;
}


/* ****************** service struct ****************** */


/**
 * Context for "service_task".
 */
struct GNUNET_SERVICE_Context
{
  /**
   * Our configuration.
   */
  const struct GNUNET_CONFIGURATION_Handle *cfg;

  /**
   * Handle for the server.
   */
  struct GNUNET_SERVER_Handle *server;

  /**
   * NULL-terminated array of addresses to bind to, NULL if we got pre-bound
   * listen sockets.
   */
  struct sockaddr **addrs;

  /**
   * Name of our service.
   */
  const char *serviceName;

  /**
   * Main service-specific task to run.
   */
  GNUNET_SERVICE_Main task;

  /**
   * Closure for task.
   */
  void *task_cls;

  /**
   * IPv4 addresses that are not allowed to connect.
   */
  struct IPv4NetworkSet *v4_denied;

  /**
   * IPv6 addresses that are not allowed to connect.
   */
  struct IPv6NetworkSet *v6_denied;

  /**
   * IPv4 addresses that are allowed to connect (if not
   * set, all are allowed).
   */
  struct IPv4NetworkSet *v4_allowed;

  /**
   * IPv6 addresses that are allowed to connect (if not
   * set, all are allowed).
   */
  struct IPv6NetworkSet *v6_allowed;

  /**
   * My (default) message handlers.  Adjusted copy
   * of "defhandlers".
   */
  struct GNUNET_SERVER_MessageHandler *my_handlers;

  /**
   * Array of the lengths of the entries in addrs.
   */
  socklen_t *addrlens;

  /**
   * NULL-terminated array of listen sockets we should take over.
   */
  struct GNUNET_NETWORK_Handle **lsocks;

  /**
   * Idle timeout for server.
   */
  struct GNUNET_TIME_Relative timeout;

  /**
   * Overall success/failure of the service start.
   */
  int ret;

  /**
   * If we are daemonizing, this FD is set to the
   * pipe to the parent.  Send '.' if we started
   * ok, '!' if not.  -1 if we are not daemonizing.
   */
  int ready_confirm_fd;

  /**
   * Do we close connections if we receive messages
   * for which we have no handler?
   */
  int require_found;

  /**
   * Do we require a matching UID for UNIX domain socket
   * connections?
   */
  int match_uid;

  /**
   * Do we require a matching GID for UNIX domain socket
   * connections?
   */
  int match_gid;

  /**
   * Our options.
   */
  enum GNUNET_SERVICE_Options options;

};


/* ****************** message handlers ****************** */

static size_t
write_test (void *cls, size_t size, void *buf)
{
  struct GNUNET_SERVER_Client *client = cls;
  struct GNUNET_MessageHeader *msg;

  if (size < sizeof (struct GNUNET_MessageHeader))
  {
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return 0;                   /* client disconnected */
  }
  msg = (struct GNUNET_MessageHeader *) buf;
  msg->type = htons (GNUNET_MESSAGE_TYPE_TEST);
  msg->size = htons (sizeof (struct GNUNET_MessageHeader));
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
  return sizeof (struct GNUNET_MessageHeader);
}

/**
 * Handler for TEST message.
 *
 * @param cls closure (refers to service)
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_test (void *cls, struct GNUNET_SERVER_Client *client,
             const struct GNUNET_MessageHeader *message)
{
  /* simply bounce message back to acknowledge */
  if (NULL ==
      GNUNET_SERVER_notify_transmit_ready (client,
                                           sizeof (struct GNUNET_MessageHeader),
                                           GNUNET_TIME_UNIT_FOREVER_REL,
                                           &write_test, client))
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
}


/**
 * Default handlers for all services.  Will be copied and the
 * "callback_cls" fields will be replaced with the specific service
 * struct.
 */
static const struct GNUNET_SERVER_MessageHandler defhandlers[] = {
  {&handle_test, NULL, GNUNET_MESSAGE_TYPE_TEST,
   sizeof (struct GNUNET_MessageHeader)},
  {NULL, NULL, 0, 0}
};



/* ****************** service core routines ************** */


/**
 * Check if access to the service is allowed from the given address.
 *
 * @param cls closure
 * @param uc credentials, if available, otherwise NULL
 * @param addr address
 * @param addrlen length of address
 * @return GNUNET_YES to allow, GNUNET_NO to deny, GNUNET_SYSERR
 *   for unknown address family (will be denied).
 */
static int
check_access (void *cls, const struct GNUNET_CONNECTION_Credentials *uc,
              const struct sockaddr *addr, socklen_t addrlen)
{
  struct GNUNET_SERVICE_Context *sctx = cls;
  const struct sockaddr_in *i4;
  const struct sockaddr_in6 *i6;
  int ret;

  switch (addr->sa_family)
  {
  case AF_INET:
    GNUNET_assert (addrlen == sizeof (struct sockaddr_in));
    i4 = (const struct sockaddr_in *) addr;
    ret = ((sctx->v4_allowed == NULL) ||
           (check_ipv4_listed (sctx->v4_allowed, &i4->sin_addr))) &&
        ((sctx->v4_denied == NULL) ||
         (!check_ipv4_listed (sctx->v4_denied, &i4->sin_addr)));
    break;
  case AF_INET6:
    GNUNET_assert (addrlen == sizeof (struct sockaddr_in6));
    i6 = (const struct sockaddr_in6 *) addr;
    ret = ((sctx->v6_allowed == NULL) ||
           (check_ipv6_listed (sctx->v6_allowed, &i6->sin6_addr))) &&
        ((sctx->v6_denied == NULL) ||
         (!check_ipv6_listed (sctx->v6_denied, &i6->sin6_addr)));
    break;
#ifndef WINDOWS
  case AF_UNIX:
    ret = GNUNET_OK;            /* always OK for now */
    if ((sctx->match_uid == GNUNET_YES) || (sctx->match_gid == GNUNET_YES))
      ret = GNUNET_NO;
    if ((uc != NULL) &&
        ((sctx->match_uid != GNUNET_YES) || (uc->uid == geteuid ()) ||
         (uc->uid == getuid ())) && ((sctx->match_gid != GNUNET_YES) ||
                                     (uc->gid == getegid ()) ||
                                     (uc->gid == getgid ())))
      ret = GNUNET_YES;
    else
      LOG (GNUNET_ERROR_TYPE_WARNING, _("Access denied to UID %d / GID %d\n"),
           (uc == NULL) ? -1 : uc->uid, (uc == NULL) ? -1 : uc->gid);
    break;
#endif
  default:
    LOG (GNUNET_ERROR_TYPE_WARNING, _("Unknown address family %d\n"),
         addr->sa_family);
    return GNUNET_SYSERR;
  }
  if (ret != GNUNET_OK)
  {
    LOG (GNUNET_ERROR_TYPE_WARNING,
         _("Access from `%s' denied to service `%s'\n"), GNUNET_a2s (addr,
                                                                     addrlen),
         sctx->serviceName);
  }
  return ret;
}


/**
 * Get the name of the file where we will
 * write the PID of the service.
 */
static char *
get_pid_file_name (struct GNUNET_SERVICE_Context *sctx)
{

  char *pif;

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (sctx->cfg, sctx->serviceName,
                                               "PIDFILE", &pif))
    return NULL;
  return pif;
}


/**
 * Parse an IPv4 access control list.
 */
static int
process_acl4 (struct IPv4NetworkSet **ret, struct GNUNET_SERVICE_Context *sctx,
              const char *option)
{
  char *opt;

  if (!GNUNET_CONFIGURATION_have_value (sctx->cfg, sctx->serviceName, option))
    return GNUNET_OK;
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONFIGURATION_get_value_string (sctx->cfg,
                                                       sctx->serviceName,
                                                       option, &opt));
  if (NULL == (*ret = parse_ipv4_specification (opt)))
  {
    LOG (GNUNET_ERROR_TYPE_WARNING,
         _("Could not parse IPv4 network specification `%s' for `%s:%s'\n"),
         opt, sctx->serviceName, option);
    GNUNET_free (opt);
    return GNUNET_SYSERR;
  }
  GNUNET_free (opt);
  return GNUNET_OK;
}


/**
 * Parse an IPv4 access control list.
 */
static int
process_acl6 (struct IPv6NetworkSet **ret, struct GNUNET_SERVICE_Context *sctx,
              const char *option)
{
  char *opt;

  if (!GNUNET_CONFIGURATION_have_value (sctx->cfg, sctx->serviceName, option))
    return GNUNET_OK;
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONFIGURATION_get_value_string (sctx->cfg,
                                                       sctx->serviceName,
                                                       option, &opt));
  if (NULL == (*ret = parse_ipv6_specification (opt)))
  {
    LOG (GNUNET_ERROR_TYPE_WARNING,
         _("Could not parse IPv6 network specification `%s' for `%s:%s'\n"),
         opt, sctx->serviceName, option);
    GNUNET_free (opt);
    return GNUNET_SYSERR;
  }
  GNUNET_free (opt);
  return GNUNET_OK;
}

/**
 * Add the given UNIX domain path as an address to the
 * list (as the first entry).
 *
 * @param saddrs array to update
 * @param saddrlens where to store the address length
 * @param unixpath path to add
 */
static void
add_unixpath (struct sockaddr **saddrs, socklen_t * saddrlens,
              const char *unixpath)
{
#ifdef AF_UNIX
  struct sockaddr_un *un;
  size_t slen;

  un = GNUNET_malloc (sizeof (struct sockaddr_un));
  un->sun_family = AF_UNIX;
  slen = strlen (unixpath) + 1;
  if (slen >= sizeof (un->sun_path))
    slen = sizeof (un->sun_path) - 1;
  memcpy (un->sun_path, unixpath, slen);
  un->sun_path[slen] = '\0';
  slen = sizeof (struct sockaddr_un);
#if LINUX
  un->sun_path[0] = '\0';
#endif
#if HAVE_SOCKADDR_IN_SIN_LEN
  un->sun_len = (u_char) slen;
#endif
  *saddrs = (struct sockaddr *) un;
  *saddrlens = slen;
#else
  /* this function should never be called
   * unless AF_UNIX is defined! */
  GNUNET_assert (0);
#endif
}


/**
 * Get the list of addresses that a server for the given service
 * should bind to.
 *
 * @param serviceName name of the service
 * @param cfg configuration (which specifies the addresses)
 * @param addrs set (call by reference) to an array of pointers to the
 *              addresses the server should bind to and listen on; the
 *              array will be NULL-terminated (on success)
 * @param addr_lens set (call by reference) to an array of the lengths
 *              of the respective 'struct sockaddr' struct in the 'addrs'
 *              array (on success)
 * @return number of addresses found on success,
 *              GNUNET_SYSERR if the configuration
 *              did not specify reasonable finding information or
 *              if it specified a hostname that could not be resolved;
 *              GNUNET_NO if the number of addresses configured is
 *              zero (in this case, '*addrs' and '*addr_lens' will be
 *              set to NULL).
 */
int
GNUNET_SERVICE_get_server_addresses (const char *serviceName,
                                     const struct GNUNET_CONFIGURATION_Handle
                                     *cfg, struct sockaddr ***addrs,
                                     socklen_t ** addr_lens)
{
  int disablev6;
  struct GNUNET_NETWORK_Handle *desc;
  unsigned long long port;
  char *unixpath;
  struct addrinfo hints;
  struct addrinfo *res;
  struct addrinfo *pos;
  struct addrinfo *next;
  unsigned int i;
  int resi;
  int ret;
  struct sockaddr **saddrs;
  socklen_t *saddrlens;
  char *hostname;

  *addrs = NULL;
  *addr_lens = NULL;
  desc = NULL;
  if (GNUNET_CONFIGURATION_have_value (cfg, serviceName, "DISABLEV6"))
  {
    if (GNUNET_SYSERR ==
        (disablev6 =
         GNUNET_CONFIGURATION_get_value_yesno (cfg, serviceName, "DISABLEV6")))
      return GNUNET_SYSERR;
  }
  else
    disablev6 = GNUNET_NO;

  if (!disablev6)
  {
    /* probe IPv6 support */
    desc = GNUNET_NETWORK_socket_create (PF_INET6, SOCK_STREAM, 0);
    if (NULL == desc)
    {
      if ((errno == ENOBUFS) || (errno == ENOMEM) || (errno == ENFILE) ||
          (errno == EACCES))
      {
        LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "socket");
        return GNUNET_SYSERR;
      }
      LOG (GNUNET_ERROR_TYPE_INFO,
           _
           ("Disabling IPv6 support for service `%s', failed to create IPv6 socket: %s\n"),
           serviceName, STRERROR (errno));
      disablev6 = GNUNET_YES;
    }
    else
    {
      GNUNET_break (GNUNET_OK == GNUNET_NETWORK_socket_close (desc));
      desc = NULL;
    }
  }

  port = 0;
  if (GNUNET_CONFIGURATION_have_value (cfg, serviceName, "PORT"))
  {
    GNUNET_break (GNUNET_OK ==
                  GNUNET_CONFIGURATION_get_value_number (cfg, serviceName,
                                                         "PORT", &port));
    if (port > 65535)
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _("Require valid port number for service `%s' in configuration!\n"),
           serviceName);
      return GNUNET_SYSERR;
    }
  }

  if (GNUNET_CONFIGURATION_have_value (cfg, serviceName, "BINDTO"))
  {
    GNUNET_break (GNUNET_OK ==
                  GNUNET_CONFIGURATION_get_value_string (cfg, serviceName,
                                                         "BINDTO", &hostname));
  }
  else
    hostname = NULL;

  unixpath = NULL;
#ifdef AF_UNIX
  if ((GNUNET_YES ==
       GNUNET_CONFIGURATION_have_value (cfg, serviceName, "UNIXPATH")) &&
      (GNUNET_OK ==
       GNUNET_CONFIGURATION_get_value_string (cfg, serviceName, "UNIXPATH",
                                              &unixpath)) &&
      (0 < strlen (unixpath)))
  {
    /* probe UNIX support */
    struct sockaddr_un s_un;

    if (strlen (unixpath) >= sizeof (s_un.sun_path))
    {
      LOG (GNUNET_ERROR_TYPE_WARNING,
           _("UNIXPATH `%s' too long, maximum length is %llu\n"), unixpath,
           sizeof (s_un.sun_path));
      GNUNET_free_non_null (hostname);
      GNUNET_free (unixpath);
      return GNUNET_SYSERR;
    }

    desc = GNUNET_NETWORK_socket_create (AF_UNIX, SOCK_STREAM, 0);
    if (NULL == desc)
    {
      if ((errno == ENOBUFS) || (errno == ENOMEM) || (errno == ENFILE) ||
          (errno == EACCES))
      {
        LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "socket");
        GNUNET_free_non_null (hostname);
        GNUNET_free (unixpath);
        return GNUNET_SYSERR;
      }
      LOG (GNUNET_ERROR_TYPE_INFO,
           _
           ("Disabling UNIX domain socket support for service `%s', failed to create UNIX domain socket: %s\n"),
           serviceName, STRERROR (errno));
      GNUNET_free (unixpath);
      unixpath = NULL;
    }
    else
    {
      GNUNET_break (GNUNET_OK == GNUNET_NETWORK_socket_close (desc));
      desc = NULL;
    }
  }
#endif

  if ((port == 0) && (unixpath == NULL))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _
         ("Have neither PORT nor UNIXPATH for service `%s', but one is required\n"),
         serviceName);
    GNUNET_free_non_null (hostname);
    return GNUNET_SYSERR;
  }
  if (port == 0)
  {
    saddrs = GNUNET_malloc (2 * sizeof (struct sockaddr *));
    saddrlens = GNUNET_malloc (2 * sizeof (socklen_t));
    add_unixpath (saddrs, saddrlens, unixpath);
    GNUNET_free_non_null (unixpath);
    GNUNET_free_non_null (hostname);
    *addrs = saddrs;
    *addr_lens = saddrlens;
    return 1;
  }

  if (hostname != NULL)
  {
#if DEBUG_SERVICE
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Resolving `%s' since that is where `%s' will bind to.\n", hostname,
         serviceName);
#endif
    memset (&hints, 0, sizeof (struct addrinfo));
    if (disablev6)
      hints.ai_family = AF_INET;
    if ((0 != (ret = getaddrinfo (hostname, NULL, &hints, &res))) ||
        (res == NULL))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR, _("Failed to resolve `%s': %s\n"), hostname,
           gai_strerror (ret));
      GNUNET_free (hostname);
      GNUNET_free_non_null (unixpath);
      return GNUNET_SYSERR;
    }
    next = res;
    i = 0;
    while (NULL != (pos = next))
    {
      next = pos->ai_next;
      if ((disablev6) && (pos->ai_family == AF_INET6))
        continue;
      i++;
    }
    if (0 == i)
    {
      LOG (GNUNET_ERROR_TYPE_ERROR, _("Failed to find %saddress for `%s'.\n"),
           disablev6 ? "IPv4 " : "", hostname);
      freeaddrinfo (res);
      GNUNET_free (hostname);
      GNUNET_free_non_null (unixpath);
      return GNUNET_SYSERR;
    }
    resi = i;
    if (NULL != unixpath)
      resi++;
    saddrs = GNUNET_malloc ((resi + 1) * sizeof (struct sockaddr *));
    saddrlens = GNUNET_malloc ((resi + 1) * sizeof (socklen_t));
    i = 0;
    if (NULL != unixpath)
    {
      add_unixpath (saddrs, saddrlens, unixpath);
      i++;
    }
    next = res;
    while (NULL != (pos = next))
    {
      next = pos->ai_next;
      if ((disablev6) && (pos->ai_family == AF_INET6))
        continue;
      if ((pos->ai_protocol != IPPROTO_TCP) && (pos->ai_protocol != 0))
        continue;               /* not TCP */
      if ((pos->ai_socktype != SOCK_STREAM) && (pos->ai_socktype != 0))
        continue;               /* huh? */
#if DEBUG_SERVICE
      LOG (GNUNET_ERROR_TYPE_DEBUG, "Service `%s' will bind to `%s'\n",
           serviceName, GNUNET_a2s (pos->ai_addr, pos->ai_addrlen));
#endif
      if (pos->ai_family == AF_INET)
      {
        GNUNET_assert (pos->ai_addrlen == sizeof (struct sockaddr_in));
        saddrlens[i] = pos->ai_addrlen;
        saddrs[i] = GNUNET_malloc (saddrlens[i]);
        memcpy (saddrs[i], pos->ai_addr, saddrlens[i]);
        ((struct sockaddr_in *) saddrs[i])->sin_port = htons (port);
      }
      else
      {
        GNUNET_assert (pos->ai_family == AF_INET6);
        GNUNET_assert (pos->ai_addrlen == sizeof (struct sockaddr_in6));
        saddrlens[i] = pos->ai_addrlen;
        saddrs[i] = GNUNET_malloc (saddrlens[i]);
        memcpy (saddrs[i], pos->ai_addr, saddrlens[i]);
        ((struct sockaddr_in6 *) saddrs[i])->sin6_port = htons (port);
      }
      i++;
    }
    GNUNET_free (hostname);
    freeaddrinfo (res);
    resi = i;
  }
  else
  {
    /* will bind against everything, just set port */
    if (disablev6)
    {
      /* V4-only */
      resi = 1;
      if (NULL != unixpath)
        resi++;
      i = 0;
      saddrs = GNUNET_malloc ((resi + 1) * sizeof (struct sockaddr *));
      saddrlens = GNUNET_malloc ((resi + 1) * sizeof (socklen_t));
      if (NULL != unixpath)
      {
        add_unixpath (saddrs, saddrlens, unixpath);
        i++;
      }
      saddrlens[i] = sizeof (struct sockaddr_in);
      saddrs[i] = GNUNET_malloc (saddrlens[i]);
#if HAVE_SOCKADDR_IN_SIN_LEN
      ((struct sockaddr_in *) saddrs[i])->sin_len = saddrlens[i];
#endif
      ((struct sockaddr_in *) saddrs[i])->sin_family = AF_INET;
      ((struct sockaddr_in *) saddrs[i])->sin_port = htons (port);
    }
    else
    {
      /* dual stack */
      resi = 2;
      if (NULL != unixpath)
        resi++;
      saddrs = GNUNET_malloc ((resi + 1) * sizeof (struct sockaddr *));
      saddrlens = GNUNET_malloc ((resi + 1) * sizeof (socklen_t));
      i = 0;
      if (NULL != unixpath)
      {
        add_unixpath (saddrs, saddrlens, unixpath);
        i++;
      }
      saddrlens[i] = sizeof (struct sockaddr_in6);
      saddrs[i] = GNUNET_malloc (saddrlens[i]);
#if HAVE_SOCKADDR_IN_SIN_LEN
      ((struct sockaddr_in6 *) saddrs[i])->sin6_len = saddrlens[0];
#endif
      ((struct sockaddr_in6 *) saddrs[i])->sin6_family = AF_INET6;
      ((struct sockaddr_in6 *) saddrs[i])->sin6_port = htons (port);
      i++;
      saddrlens[i] = sizeof (struct sockaddr_in);
      saddrs[i] = GNUNET_malloc (saddrlens[i]);
#if HAVE_SOCKADDR_IN_SIN_LEN
      ((struct sockaddr_in *) saddrs[i])->sin_len = saddrlens[1];
#endif
      ((struct sockaddr_in *) saddrs[i])->sin_family = AF_INET;
      ((struct sockaddr_in *) saddrs[i])->sin_port = htons (port);
    }
  }
  GNUNET_free_non_null (unixpath);
  *addrs = saddrs;
  *addr_lens = saddrlens;
  return resi;
}


/**
 * Setup addr, addrlen, idle_timeout
 * based on configuration!
 *
 * Configuration may specify:
 * - PORT (where to bind to for TCP)
 * - UNIXPATH (where to bind to for UNIX domain sockets)
 * - TIMEOUT (after how many ms does an inactive service timeout);
 * - DISABLEV6 (disable support for IPv6, otherwise we use dual-stack)
 * - BINDTO (hostname or IP address to bind to, otherwise we take everything)
 * - ACCEPT_FROM  (only allow connections from specified IPv4 subnets)
 * - ACCEPT_FROM6 (only allow connections from specified IPv6 subnets)
 * - REJECT_FROM  (disallow allow connections from specified IPv4 subnets)
 * - REJECT_FROM6 (disallow allow connections from specified IPv6 subnets)
 *
 * @return GNUNET_OK if configuration succeeded
 */
static int
setup_service (struct GNUNET_SERVICE_Context *sctx)
{
  struct GNUNET_TIME_Relative idleout;
  int tolerant;

#ifndef MINGW
  const char *lpid;
  unsigned int pid;
  const char *nfds;
  unsigned int cnt;
  int flags;
#endif

  if (GNUNET_CONFIGURATION_have_value (sctx->cfg, sctx->serviceName, "TIMEOUT"))
  {
    if (GNUNET_OK !=
        GNUNET_CONFIGURATION_get_value_time (sctx->cfg, sctx->serviceName,
                                             "TIMEOUT", &idleout))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _("Specified value for `%s' of service `%s' is invalid\n"),
           "TIMEOUT", sctx->serviceName);
      return GNUNET_SYSERR;
    }
    sctx->timeout = idleout;
  }
  else
    sctx->timeout = GNUNET_TIME_UNIT_FOREVER_REL;

  if (GNUNET_CONFIGURATION_have_value
      (sctx->cfg, sctx->serviceName, "TOLERANT"))
  {
    if (GNUNET_SYSERR ==
        (tolerant =
         GNUNET_CONFIGURATION_get_value_yesno (sctx->cfg, sctx->serviceName,
                                               "TOLERANT")))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _("Specified value for `%s' of service `%s' is invalid\n"),
           "TOLERANT", sctx->serviceName);
      return GNUNET_SYSERR;
    }
  }
  else
    tolerant = GNUNET_NO;

#ifndef MINGW
  errno = 0;
  if ((NULL != (lpid = getenv ("LISTEN_PID"))) &&
      (1 == sscanf (lpid, "%u", &pid)) && (getpid () == (pid_t) pid) &&
      (NULL != (nfds = getenv ("LISTEN_FDS"))) &&
      (1 == sscanf (nfds, "%u", &cnt)) && (cnt > 0) && (cnt < FD_SETSIZE) &&
      (cnt + 4 < FD_SETSIZE))
  {
    sctx->lsocks =
        GNUNET_malloc (sizeof (struct GNUNET_NETWORK_Handle *) * (cnt + 1));
    while (0 < cnt--)
    {
      flags = fcntl (3 + cnt, F_GETFD);
      if ((flags < 0) || (0 != (flags & FD_CLOEXEC)) ||
          (NULL ==
           (sctx->lsocks[cnt] = GNUNET_NETWORK_socket_box_native (3 + cnt))))
      {
        LOG (GNUNET_ERROR_TYPE_ERROR,
             _
             ("Could not access pre-bound socket %u, will try to bind myself\n"),
             (unsigned int) 3 + cnt);
        cnt++;
        while (sctx->lsocks[cnt] != NULL)
          GNUNET_break (0 == GNUNET_NETWORK_socket_close (sctx->lsocks[cnt++]));
        GNUNET_free (sctx->lsocks);
        sctx->lsocks = NULL;
        break;
      }
    }
    unsetenv ("LISTEN_PID");
    unsetenv ("LISTEN_FDS");
  }
#endif

  if ((sctx->lsocks == NULL) &&
      (GNUNET_SYSERR ==
       GNUNET_SERVICE_get_server_addresses (sctx->serviceName, sctx->cfg,
                                            &sctx->addrs, &sctx->addrlens)))
    return GNUNET_SYSERR;
  sctx->require_found = tolerant ? GNUNET_NO : GNUNET_YES;
  sctx->match_uid =
      GNUNET_CONFIGURATION_get_value_yesno (sctx->cfg, sctx->serviceName,
                                            "UNIX_MATCH_UID");
  sctx->match_gid =
      GNUNET_CONFIGURATION_get_value_yesno (sctx->cfg, sctx->serviceName,
                                            "UNIX_MATCH_GID");
  process_acl4 (&sctx->v4_denied, sctx, "REJECT_FROM");
  process_acl4 (&sctx->v4_allowed, sctx, "ACCEPT_FROM");
  process_acl6 (&sctx->v6_denied, sctx, "REJECT_FROM6");
  process_acl6 (&sctx->v6_allowed, sctx, "ACCEPT_FROM6");

  return GNUNET_OK;
}


/**
 * Get the name of the user that'll be used
 * to provide the service.
 */
static char *
get_user_name (struct GNUNET_SERVICE_Context *sctx)
{

  char *un;

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (sctx->cfg, sctx->serviceName,
                                               "USERNAME", &un))
    return NULL;
  return un;
}

/**
 * Write PID file.
 */
static int
write_pid_file (struct GNUNET_SERVICE_Context *sctx, pid_t pid)
{
  FILE *pidfd;
  char *pif;
  char *user;
  char *rdir;
  int len;

  if (NULL == (pif = get_pid_file_name (sctx)))
    return GNUNET_OK;           /* no file desired */
  user = get_user_name (sctx);
  rdir = GNUNET_strdup (pif);
  len = strlen (rdir);
  while ((len > 0) && (rdir[len] != DIR_SEPARATOR))
    len--;
  rdir[len] = '\0';
  if (0 != ACCESS (rdir, F_OK))
  {
    /* we get to create a directory -- and claim it
     * as ours! */
    GNUNET_DISK_directory_create (rdir);
    if ((user != NULL) && (0 < strlen (user)))
      GNUNET_DISK_file_change_owner (rdir, user);
  }
  if (0 != ACCESS (rdir, W_OK | X_OK))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "access", rdir);
    GNUNET_free (rdir);
    GNUNET_free_non_null (user);
    GNUNET_free (pif);
    return GNUNET_SYSERR;
  }
  GNUNET_free (rdir);
  pidfd = FOPEN (pif, "w");
  if (pidfd == NULL)
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "fopen", pif);
    GNUNET_free (pif);
    GNUNET_free_non_null (user);
    return GNUNET_SYSERR;
  }
  if (0 > FPRINTF (pidfd, "%u", pid))
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fprintf", pif);
  GNUNET_break (0 == fclose (pidfd));
  if ((user != NULL) && (0 < strlen (user)))
    GNUNET_DISK_file_change_owner (pif, user);
  GNUNET_free_non_null (user);
  GNUNET_free (pif);
  return GNUNET_OK;
}


/**
 * Task run during shutdown.
 *
 * @param cls unused
 * @param tc unused
 */
static void
shutdown_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct GNUNET_SERVER_Handle *server = cls;

  GNUNET_SERVER_destroy (server);
}


/**
 * Initial task for the service.
 */
static void
service_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct GNUNET_SERVICE_Context *sctx = cls;
  unsigned int i;

  GNUNET_RESOLVER_connect (sctx->cfg);
  if (sctx->lsocks != NULL)
    sctx->server =
        GNUNET_SERVER_create_with_sockets (&check_access, sctx, sctx->lsocks,
                                           sctx->timeout, sctx->require_found);
  else
    sctx->server =
        GNUNET_SERVER_create (&check_access, sctx, sctx->addrs, sctx->addrlens,
                              sctx->timeout, sctx->require_found);
  if (sctx->server == NULL)
  {
    if (sctx->addrs != NULL)
    {
      i = 0;
      while (sctx->addrs[i] != NULL)
      {
        LOG (GNUNET_ERROR_TYPE_INFO, _("Failed to start `%s' at `%s'\n"),
             sctx->serviceName, GNUNET_a2s (sctx->addrs[i], sctx->addrlens[i]));
        i++;
      }
    }
    sctx->ret = GNUNET_SYSERR;
    return;
  }
  if (0 == (sctx->options & GNUNET_SERVICE_OPTION_MANUAL_SHUTDOWN))
  {
    /* install a task that will kill the server
     * process if the scheduler ever gets a shutdown signal */
    GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL, &shutdown_task,
                                  sctx->server);
  }
  sctx->my_handlers = GNUNET_malloc (sizeof (defhandlers));
  memcpy (sctx->my_handlers, defhandlers, sizeof (defhandlers));
  i = 0;
  while ((sctx->my_handlers[i].callback != NULL))
    sctx->my_handlers[i++].callback_cls = sctx;
  GNUNET_SERVER_add_handlers (sctx->server, sctx->my_handlers);
  if (sctx->ready_confirm_fd != -1)
  {
    GNUNET_break (1 == WRITE (sctx->ready_confirm_fd, ".", 1));
    GNUNET_break (0 == CLOSE (sctx->ready_confirm_fd));
    sctx->ready_confirm_fd = -1;
    write_pid_file (sctx, getpid ());
  }
  if (sctx->addrs != NULL)
  {
    i = 0;
    while (sctx->addrs[i] != NULL)
    {
      LOG (GNUNET_ERROR_TYPE_INFO, _("Service `%s' runs at %s\n"),
           sctx->serviceName, GNUNET_a2s (sctx->addrs[i], sctx->addrlens[i]));
      i++;
    }
  }
  sctx->task (sctx->task_cls, sctx->server, sctx->cfg);
}


/**
 * Detach from terminal.
 */
static int
detach_terminal (struct GNUNET_SERVICE_Context *sctx)
{
#ifndef MINGW
  pid_t pid;
  int nullfd;
  int filedes[2];

  if (0 != PIPE (filedes))
  {
    LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "pipe");
    return GNUNET_SYSERR;
  }
  pid = fork ();
  if (pid < 0)
  {
    LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "fork");
    return GNUNET_SYSERR;
  }
  if (pid != 0)
  {
    /* Parent */
    char c;

    GNUNET_break (0 == CLOSE (filedes[1]));
    c = 'X';
    if (1 != READ (filedes[0], &c, sizeof (char)))
      LOG_STRERROR (GNUNET_ERROR_TYPE_WARNING, "read");
    fflush (stdout);
    switch (c)
    {
    case '.':
      exit (0);
    case 'I':
      LOG (GNUNET_ERROR_TYPE_INFO, _("Service process failed to initialize\n"));
      break;
    case 'S':
      LOG (GNUNET_ERROR_TYPE_INFO,
           _("Service process could not initialize server function\n"));
      break;
    case 'X':
      LOG (GNUNET_ERROR_TYPE_INFO,
           _("Service process failed to report status\n"));
      break;
    }
    exit (1);                   /* child reported error */
  }
  GNUNET_break (0 == CLOSE (0));
  GNUNET_break (0 == CLOSE (1));
  GNUNET_break (0 == CLOSE (filedes[0]));
  nullfd = OPEN ("/dev/null", O_RDWR | O_APPEND);
  if (nullfd < 0)
    return GNUNET_SYSERR;
  /* set stdin/stdout to /dev/null */
  if ((dup2 (nullfd, 0) < 0) || (dup2 (nullfd, 1) < 0))
  {
    LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "dup2");
    (void) CLOSE (nullfd);
    return GNUNET_SYSERR;
  }
  (void) CLOSE (nullfd);
  /* Detach from controlling terminal */
  pid = setsid ();
  if (pid == -1)
    LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "setsid");
  sctx->ready_confirm_fd = filedes[1];
#else
  /* FIXME: we probably need to do something else
   * elsewhere in order to fork the process itself... */
  FreeConsole ();
#endif
  return GNUNET_OK;
}


/**
 * Set user ID.
 */
static int
set_user_id (struct GNUNET_SERVICE_Context *sctx)
{
  char *user;

  if (NULL == (user = get_user_name (sctx)))
    return GNUNET_OK;           /* keep */
#ifndef MINGW
  struct passwd *pws;

  errno = 0;
  pws = getpwnam (user);
  if (pws == NULL)
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _("Cannot obtain information about user `%s': %s\n"), user,
         errno == 0 ? _("No such user") : STRERROR (errno));
    GNUNET_free (user);
    return GNUNET_SYSERR;
  }
  if ((0 != setgid (pws->pw_gid)) || (0 != setegid (pws->pw_gid)) ||
#if HAVE_INITGROUPS
      (0 != initgroups (user, pws->pw_gid)) ||
#endif
      (0 != setuid (pws->pw_uid)) || (0 != seteuid (pws->pw_uid)))
  {
    if ((0 != setregid (pws->pw_gid, pws->pw_gid)) ||
        (0 != setreuid (pws->pw_uid, pws->pw_uid)))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR, _("Cannot change user/group to `%s': %s\n"),
           user, STRERROR (errno));
      GNUNET_free (user);
      return GNUNET_SYSERR;
    }
  }
#endif
  GNUNET_free (user);
  return GNUNET_OK;
}


/**
 * Delete the PID file that was created by our parent.
 */
static void
pid_file_delete (struct GNUNET_SERVICE_Context *sctx)
{
  char *pif = get_pid_file_name (sctx);

  if (pif == NULL)
    return;                     /* no PID file */
  if (0 != UNLINK (pif))
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", pif);
  GNUNET_free (pif);
}


/**
 * Run a standard GNUnet service startup sequence (initialize loggers
 * and configuration, parse options).
 *
 * @param argc number of command line arguments
 * @param argv command line arguments
 * @param serviceName our service name
 * @param opt service options
 * @param task main task of the service
 * @param task_cls closure for task
 * @return GNUNET_SYSERR on error, GNUNET_OK
 *         if we shutdown nicely
 */
int
GNUNET_SERVICE_run (int argc, char *const *argv, const char *serviceName,
                    enum GNUNET_SERVICE_Options opt, GNUNET_SERVICE_Main task,
                    void *task_cls)
{
#define HANDLE_ERROR do { GNUNET_break (0); goto shutdown; } while (0)

  int err;
  char *cfg_fn;
  char *loglev;
  char *logfile;
  int do_daemonize;
  unsigned int i;
  unsigned long long skew_offset;
  unsigned long long skew_variance;
  long long clock_offset;
  struct GNUNET_SERVICE_Context sctx;
  struct GNUNET_CONFIGURATION_Handle *cfg;

  struct GNUNET_GETOPT_CommandLineOption service_options[] = {
    GNUNET_GETOPT_OPTION_CFG_FILE (&cfg_fn),
    {'d', "daemonize", NULL,
     gettext_noop ("do daemonize (detach from terminal)"), 0,
     GNUNET_GETOPT_set_one, &do_daemonize},
    GNUNET_GETOPT_OPTION_HELP (serviceName),
    GNUNET_GETOPT_OPTION_LOGLEVEL (&loglev),
    GNUNET_GETOPT_OPTION_LOGFILE (&logfile),
    GNUNET_GETOPT_OPTION_VERSION (PACKAGE_VERSION),
    GNUNET_GETOPT_OPTION_END
  };
  err = 1;
  do_daemonize = 0;
  logfile = NULL;
  loglev = NULL;
  cfg_fn = GNUNET_strdup (GNUNET_DEFAULT_USER_CONFIG_FILE);
  memset (&sctx, 0, sizeof (sctx));
  sctx.options = opt;
  sctx.ready_confirm_fd = -1;
  sctx.ret = GNUNET_OK;
  sctx.timeout = GNUNET_TIME_UNIT_FOREVER_REL;
  sctx.task = task;
  sctx.task_cls = task_cls;
  sctx.serviceName = serviceName;
  sctx.cfg = cfg = GNUNET_CONFIGURATION_create ();
  /* setup subsystems */
  if (GNUNET_SYSERR ==
      GNUNET_GETOPT_run (serviceName, service_options, argc, argv))
    goto shutdown;
  if (GNUNET_OK != GNUNET_log_setup (serviceName, loglev, logfile))
    HANDLE_ERROR;
  if (GNUNET_OK != GNUNET_CONFIGURATION_load (cfg, cfg_fn))
    goto shutdown;
  if (GNUNET_OK != setup_service (&sctx))
    goto shutdown;
  if ((do_daemonize == 1) && (GNUNET_OK != detach_terminal (&sctx)))
    HANDLE_ERROR;
  if (GNUNET_OK != set_user_id (&sctx))
    goto shutdown;
#if DEBUG_SERVICE
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Service `%s' runs with configuration from `%s'\n", serviceName, cfg_fn);
#endif
  if ((GNUNET_OK ==
       GNUNET_CONFIGURATION_get_value_number (sctx.cfg, "TESTING",
                                              "SKEW_OFFSET", &skew_offset)) &&
      (GNUNET_OK ==
       GNUNET_CONFIGURATION_get_value_number (sctx.cfg, "TESTING",
                                              "SKEW_VARIANCE", &skew_variance)))
  {
    clock_offset = skew_offset - skew_variance;
    GNUNET_TIME_set_offset (clock_offset);
#if DEBUG_SERVICE
    LOG (GNUNET_ERROR_TYPE_DEBUG, "Skewing clock by %dll ms\n", clock_offset);
#endif
  }
  /* actually run service */
  err = 0;
  GNUNET_SCHEDULER_run (&service_task, &sctx);

  /* shutdown */
  if ((do_daemonize == 1) && (sctx.server != NULL))
    pid_file_delete (&sctx);
  GNUNET_free_non_null (sctx.my_handlers);

shutdown:
  if (sctx.ready_confirm_fd != -1)
  {
    if (1 != WRITE (sctx.ready_confirm_fd, err ? "I" : "S", 1))
      LOG_STRERROR (GNUNET_ERROR_TYPE_WARNING, "write");
    GNUNET_break (0 == CLOSE (sctx.ready_confirm_fd));
  }

  GNUNET_CONFIGURATION_destroy (cfg);
  i = 0;
  if (sctx.addrs != NULL)
    while (sctx.addrs[i] != NULL)
      GNUNET_free (sctx.addrs[i++]);
  GNUNET_free_non_null (sctx.addrs);
  GNUNET_free_non_null (sctx.addrlens);
  GNUNET_free_non_null (logfile);
  GNUNET_free_non_null (loglev);
  GNUNET_free (cfg_fn);
  GNUNET_free_non_null (sctx.v4_denied);
  GNUNET_free_non_null (sctx.v6_denied);
  GNUNET_free_non_null (sctx.v4_allowed);
  GNUNET_free_non_null (sctx.v6_allowed);

  return err ? GNUNET_SYSERR : sctx.ret;
}


/**
 * Run a service startup sequence within an existing
 * initialized system.
 *
 * @param serviceName our service name
 * @param cfg configuration to use
 * @return NULL on error, service handle
 */
struct GNUNET_SERVICE_Context *
GNUNET_SERVICE_start (const char *serviceName,
                      const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  int i;
  struct GNUNET_SERVICE_Context *sctx;

  sctx = GNUNET_malloc (sizeof (struct GNUNET_SERVICE_Context));
  sctx->ready_confirm_fd = -1;  /* no daemonizing */
  sctx->ret = GNUNET_OK;
  sctx->timeout = GNUNET_TIME_UNIT_FOREVER_REL;
  sctx->serviceName = serviceName;
  sctx->cfg = cfg;

  /* setup subsystems */
  if (GNUNET_OK != setup_service (sctx))
  {
    GNUNET_SERVICE_stop (sctx);
    return NULL;
  }
  if (sctx->lsocks != NULL)
    sctx->server =
        GNUNET_SERVER_create_with_sockets (&check_access, sctx, sctx->lsocks,
                                           sctx->timeout, sctx->require_found);
  else
    sctx->server =
        GNUNET_SERVER_create (&check_access, sctx, sctx->addrs, sctx->addrlens,
                              sctx->timeout, sctx->require_found);

  if (NULL == sctx->server)
  {
    GNUNET_SERVICE_stop (sctx);
    return NULL;
  }
  sctx->my_handlers = GNUNET_malloc (sizeof (defhandlers));
  memcpy (sctx->my_handlers, defhandlers, sizeof (defhandlers));
  i = 0;
  while ((sctx->my_handlers[i].callback != NULL))
    sctx->my_handlers[i++].callback_cls = sctx;
  GNUNET_SERVER_add_handlers (sctx->server, sctx->my_handlers);
  return sctx;
}

/**
 * Obtain the server used by a service.  Note that the server must NOT
 * be destroyed by the caller.
 *
 * @param ctx the service context returned from the start function
 * @return handle to the server for this service, NULL if there is none
 */
struct GNUNET_SERVER_Handle *
GNUNET_SERVICE_get_server (struct GNUNET_SERVICE_Context *ctx)
{
  return ctx->server;
}


/**
 * Stop a service that was started with "GNUNET_SERVICE_start".
 *
 * @param sctx the service context returned from the start function
 */
void
GNUNET_SERVICE_stop (struct GNUNET_SERVICE_Context *sctx)
{
  unsigned int i;

  if (NULL != sctx->server)
    GNUNET_SERVER_destroy (sctx->server);
  GNUNET_free_non_null (sctx->my_handlers);
  if (sctx->addrs != NULL)
  {
    i = 0;
    while (sctx->addrs[i] != NULL)
      GNUNET_free (sctx->addrs[i++]);
    GNUNET_free (sctx->addrs);
  }
  GNUNET_free_non_null (sctx->addrlens);
  GNUNET_free_non_null (sctx->v4_denied);
  GNUNET_free_non_null (sctx->v6_denied);
  GNUNET_free_non_null (sctx->v4_allowed);
  GNUNET_free_non_null (sctx->v6_allowed);
  GNUNET_free (sctx);
}


/* end of service.c */