gnunet/src/hostlist/hostlist-server.c

/*
     This file is part of GNUnet.
     (C) 2008, 2009, 2010 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 3, 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 hostlist/hostlist-server.c
 * @author Christian Grothoff, Matthias Wachs
 * @brief application to provide an integrated hostlist HTTP server
 */

#include "platform.h"
#include <microhttpd.h>
#include "hostlist-server.h"
#include "gnunet_hello_lib.h"
#include "gnunet_peerinfo_service.h"
#include "gnunet-daemon-hostlist.h"
#include "gnunet_resolver_service.h"

#define DEBUG_HOSTLIST_SERVER GNUNET_NO

/**
 * Handle to the HTTP server as provided by libmicrohttpd for IPv6.
 */
static struct MHD_Daemon *daemon_handle_v6;

/**
 * Handle to the HTTP server as provided by libmicrohttpd for IPv4.
 */
static struct MHD_Daemon *daemon_handle_v4;

/**
 * Our configuration.
 */
static const struct GNUNET_CONFIGURATION_Handle *cfg;

/**
 * For keeping statistics.
 */
static struct GNUNET_STATISTICS_Handle *stats;

/**
 * Handle to the core service (NULL until we've connected to it).
 */
static struct GNUNET_CORE_Handle *core;

/**
 * Handle to the peerinfo notify service (NULL until we've connected to it).
 */
static struct GNUNET_PEERINFO_NotifyContext *notify;

/**
 * Our primary task for IPv4.
 */
static GNUNET_SCHEDULER_TaskIdentifier hostlist_task_v4;

/**
 * Our primary task for IPv6.
 */
static GNUNET_SCHEDULER_TaskIdentifier hostlist_task_v6;

/**
 * Our canonical response.
 */
static struct MHD_Response *response;

/**
 * NULL if we are not currenlty iterating over peer information.
 */
static struct GNUNET_PEERINFO_IteratorContext *pitr;

/**
 * Handle for accessing peerinfo service.
 */
static struct GNUNET_PEERINFO_Handle *peerinfo;

/**
 * Context for host processor.
 */
struct HostSet
{
  unsigned int size;

  char *data;
};

/**
 * Set if we are allowed to advertise our hostlist to others.
 */
static int advertising;

/**
 * Buffer for the hostlist address
 */
static char *hostlist_uri;


/**
 * Function that assembles our response.
 */
static void
finish_response (struct HostSet *results)
{
  if (response != NULL)
    MHD_destroy_response (response);
#if DEBUG_HOSTLIST_SERVER
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Creating hostlist response with %u bytes\n",
              (unsigned int) results->size);
#endif
  response =
      MHD_create_response_from_data (results->size, results->data, MHD_YES,
                                     MHD_NO);
  if ((daemon_handle_v4 == NULL) && (daemon_handle_v6 == NULL))
  {
    MHD_destroy_response (response);
    response = NULL;
  }
  GNUNET_STATISTICS_set (stats, gettext_noop ("bytes in hostlist"),
                         results->size, GNUNET_YES);
  GNUNET_free (results);
}


/**
 * Set 'cls' to GNUNET_YES (we have an address!).
 *
 * @param cls closure, an 'int*'
 * @param tname name of the transport (ignored)
 * @param expiration expiration time (call is ignored if this is in the past)
 * @param addr the address (ignored)
 * @param addrlen length of the address (ignored)
 * @return  GNUNET_SYSERR to stop iterating (unless expiration has occured)
 */
static int
check_has_addr (void *cls, const char *tname,
                struct GNUNET_TIME_Absolute expiration, const void *addr,
                uint16_t addrlen)
{
  int *arg = cls;

  if (GNUNET_TIME_absolute_get_remaining (expiration).rel_value == 0)
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("expired addresses encountered"), 1,
                              GNUNET_YES);
    return GNUNET_YES;          /* ignore this address */
  }
  *arg = GNUNET_YES;
  return GNUNET_SYSERR;
}


/**
 * Callback that processes each of the known HELLOs for the
 * hostlist response construction.
 */
static void
host_processor (void *cls, const struct GNUNET_PeerIdentity *peer,
                const struct GNUNET_HELLO_Message *hello, const char *err_msg)
{
  struct HostSet *results = cls;
  size_t old;
  size_t s;
  int has_addr;

  if (err_msg != NULL)
  {
    GNUNET_assert (NULL == peer);
    pitr = NULL;
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _("Error in communication with PEERINFO service: %s\n"),
                err_msg);
    return;
  }
  if (peer == NULL)
  {
    pitr = NULL;
    finish_response (results);
    return;
  }
  if (hello == NULL)
    return;
  has_addr = GNUNET_NO;
  GNUNET_HELLO_iterate_addresses (hello, GNUNET_NO, &check_has_addr, &has_addr);
  if (GNUNET_NO == has_addr)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "HELLO for peer `%4s' has no address, not suitable for hostlist!\n",
                GNUNET_i2s (peer));
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("HELLOs without addresses encountered (ignored)"),
                              1, GNUNET_NO);
    return;
  }
  old = results->size;
  s = GNUNET_HELLO_size (hello);
#if DEBUG_HOSTLIST_SERVER
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received %u bytes of `%s' from peer `%s' for hostlist.\n",
              (unsigned int) s, "HELLO", GNUNET_i2s (peer));
#endif
  if ((old + s >= GNUNET_MAX_MALLOC_CHECKED) ||
      (old + s >= MAX_BYTES_PER_HOSTLISTS))
  {
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("bytes not included in hostlist (size limit)"),
                              s, GNUNET_NO);
    return;                     /* too large, skip! */
  }
#if DEBUG_HOSTLIST_SERVER
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Adding peer `%s' to hostlist (%u bytes)\n", GNUNET_i2s (peer),
              (unsigned int) s);
#endif
  GNUNET_array_grow (results->data, results->size, old + s);
  memcpy (&results->data[old], hello, s);
}



/**
 * Hostlist access policy (very permissive, allows everything).
 */
static int
accept_policy_callback (void *cls, const struct sockaddr *addr,
                        socklen_t addrlen)
{
  if (NULL == response)
  {
#if DEBUG_HOSTLIST_SERVER
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Received request for hostlist, but I am not yet ready; rejecting!\n");
#endif
    return MHD_NO;
  }
  return MHD_YES;               /* accept all */
}


/**
 * Main request handler.
 */
static int
access_handler_callback (void *cls, struct MHD_Connection *connection,
                         const char *url, const char *method,
                         const char *version, const char *upload_data,
                         size_t * upload_data_size, void **con_cls)
{
  static int dummy;

  if (0 != strcmp (method, MHD_HTTP_METHOD_GET))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _("Refusing `%s' request to hostlist server\n"), method);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("hostlist requests refused (not HTTP GET)"), 1,
                              GNUNET_YES);
    return MHD_NO;
  }
  if (NULL == *con_cls)
  {
    (*con_cls) = &dummy;
#if DEBUG_HOSTLIST_SERVER
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _("Sending 100 CONTINUE reply\n"));
#endif
    return MHD_YES;             /* send 100 continue */
  }
  if (*upload_data_size != 0)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _("Refusing `%s' request with %llu bytes of upload data\n"),
                method, (unsigned long long) *upload_data_size);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("hostlist requests refused (upload data)"), 1,
                              GNUNET_YES);
    return MHD_NO;              /* do not support upload data */
  }
  if (response == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _
                ("Could not handle hostlist request since I do not have a response yet\n"));
    GNUNET_STATISTICS_update (stats,
                              gettext_noop
                              ("hostlist requests refused (not ready)"), 1,
                              GNUNET_YES);
    return MHD_NO;              /* internal error, no response yet */
  }
  GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Received request for our hostlist\n"));
  GNUNET_STATISTICS_update (stats, gettext_noop ("hostlist requests processed"),
                            1, GNUNET_YES);
  return MHD_queue_response (connection, MHD_HTTP_OK, response);
}


/**
 * Handler called by core when core is ready to transmit message
 * @param cls   closure
 * @param size  size of buffer to copy message to
 * @param buf   buffer to copy message to
 */
static size_t
adv_transmit_ready (void *cls, size_t size, void *buf)
{
  static uint64_t hostlist_adv_count;

  size_t transmission_size;
  size_t uri_size;              /* Including \0 termination! */
  struct GNUNET_MessageHeader header;
  char *cbuf;

  if (buf == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Transmission failed, buffer invalid!\n");
    return 0;
  }
  uri_size = strlen (hostlist_uri) + 1;
  transmission_size = sizeof (struct GNUNET_MessageHeader) + uri_size;
  header.type = htons (GNUNET_MESSAGE_TYPE_HOSTLIST_ADVERTISEMENT);
  header.size = htons (transmission_size);
  GNUNET_assert (size >= transmission_size);
  memcpy (buf, &header, sizeof (struct GNUNET_MessageHeader));
  cbuf = buf;
  memcpy (&cbuf[sizeof (struct GNUNET_MessageHeader)], hostlist_uri, uri_size);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sent advertisement message: Copied %u bytes into buffer!\n",
              (unsigned int) transmission_size);
  hostlist_adv_count++;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, " # Sent advertisement message: %u\n",
              hostlist_adv_count);
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# hostlist advertisements send"), 1,
                            GNUNET_NO);
  return transmission_size;
}


/**
 * Method called whenever a given peer connects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 * @param atsi performance data
 */
static void
connect_handler (void *cls, const struct GNUNET_PeerIdentity *peer,
                 const struct GNUNET_TRANSPORT_ATS_Information *atsi)
{
  size_t size;

  if (!advertising)
    return;
  if (hostlist_uri == NULL)
    return;
  size = strlen (hostlist_uri) + 1;
  if (size + sizeof (struct GNUNET_MessageHeader) >=
      GNUNET_SERVER_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    return;
  }
  size += sizeof (struct GNUNET_MessageHeader);
  if (NULL == core)
  {
    GNUNET_break (0);
    return;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Asked core to transmit advertisement message with a size of %u bytes to peer `%s'\n",
              size, GNUNET_i2s (peer));
  if (NULL ==
      GNUNET_CORE_notify_transmit_ready (core, GNUNET_YES, 0,
                                         GNUNET_ADV_TIMEOUT, peer, size,
                                         &adv_transmit_ready, NULL))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _("Advertisement message could not be queued by core\n"));
  }
}


/**
 * Method called whenever a given peer disconnects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 */
static void
disconnect_handler (void *cls, const struct GNUNET_PeerIdentity *peer)
{
  /* nothing to do */
}

/**
 * PEERINFO calls this function to let us know about a possible peer
 * that we might want to connect to.
 *
 * @param cls closure (not used)
 * @param peer potential peer to connect to
 * @param hello HELLO for this peer (or NULL)
 * @param err_msg NULL if successful, otherwise contains error message
 */
static void
process_notify (void *cls, const struct GNUNET_PeerIdentity *peer,
                const struct GNUNET_HELLO_Message *hello, const char *err_msg)
{
  struct HostSet *results;

#if DEBUG_HOSTLIST_SERVER
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Peerinfo is notifying us to rebuild our hostlist\n");
#endif
  if (err_msg != NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _("Error in communication with PEERINFO service\n"));
    /* return; */
  }
  results = GNUNET_malloc (sizeof (struct HostSet));
  GNUNET_assert (peerinfo != NULL);
  pitr =
      GNUNET_PEERINFO_iterate (peerinfo, NULL, GNUNET_TIME_UNIT_MINUTES,
                               &host_processor, results);
}

/**
 * Function that queries MHD's select sets and
 * starts the task waiting for them.
 */
static GNUNET_SCHEDULER_TaskIdentifier
prepare_daemon (struct MHD_Daemon *daemon_handle);


/**
 * Call MHD to process pending requests and then go back
 * and schedule the next run.
 */
static void
run_daemon (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct MHD_Daemon *daemon_handle = cls;

  if (daemon_handle == daemon_handle_v4)
    hostlist_task_v4 = GNUNET_SCHEDULER_NO_TASK;
  else
    hostlist_task_v6 = GNUNET_SCHEDULER_NO_TASK;

  if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
    return;
  GNUNET_assert (MHD_YES == MHD_run (daemon_handle));
  if (daemon_handle == daemon_handle_v4)
    hostlist_task_v4 = prepare_daemon (daemon_handle);
  else
    hostlist_task_v6 = prepare_daemon (daemon_handle);
}


/**
 * Function that queries MHD's select sets and
 * starts the task waiting for them.
 */
static GNUNET_SCHEDULER_TaskIdentifier
prepare_daemon (struct MHD_Daemon *daemon_handle)
{
  GNUNET_SCHEDULER_TaskIdentifier ret;
  fd_set rs;
  fd_set ws;
  fd_set es;
  struct GNUNET_NETWORK_FDSet *wrs;
  struct GNUNET_NETWORK_FDSet *wws;
  struct GNUNET_NETWORK_FDSet *wes;
  int max;
  unsigned long long timeout;
  int haveto;
  struct GNUNET_TIME_Relative tv;

  FD_ZERO (&rs);
  FD_ZERO (&ws);
  FD_ZERO (&es);
  wrs = GNUNET_NETWORK_fdset_create ();
  wes = GNUNET_NETWORK_fdset_create ();
  wws = GNUNET_NETWORK_fdset_create ();
  max = -1;
  GNUNET_assert (MHD_YES == MHD_get_fdset (daemon_handle, &rs, &ws, &es, &max));
  haveto = MHD_get_timeout (daemon_handle, &timeout);
  if (haveto == MHD_YES)
    tv.rel_value = (uint64_t) timeout;
  else
    tv = GNUNET_TIME_UNIT_FOREVER_REL;
  GNUNET_NETWORK_fdset_copy_native (wrs, &rs, max + 1);
  GNUNET_NETWORK_fdset_copy_native (wws, &ws, max + 1);
  GNUNET_NETWORK_fdset_copy_native (wes, &es, max + 1);
  ret =
      GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_HIGH,
                                   GNUNET_SCHEDULER_NO_TASK, tv, wrs, wws,
                                   &run_daemon, daemon_handle);
  GNUNET_NETWORK_fdset_destroy (wrs);
  GNUNET_NETWORK_fdset_destroy (wws);
  GNUNET_NETWORK_fdset_destroy (wes);
  return ret;
}



/**
 * Start server offering our hostlist.
 *
 * @return GNUNET_OK on success
 */
int
GNUNET_HOSTLIST_server_start (const struct GNUNET_CONFIGURATION_Handle *c,
                              struct GNUNET_STATISTICS_Handle *st,
                              struct GNUNET_CORE_Handle *co,
                              GNUNET_CORE_ConnectEventHandler *server_ch,
                              GNUNET_CORE_DisconnectEventHandler *server_dh,
                              int advertise)
{
  unsigned long long port;
  char *hostname;
  size_t size;

  advertising = advertise;
  if (!advertising)
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Advertising not enabled on this hostlist server\n");
  else
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Advertising enabled on this hostlist server\n");
  cfg = c;
  stats = st;
  peerinfo = GNUNET_PEERINFO_connect (cfg);
  if (peerinfo == NULL)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Could not access PEERINFO service.  Exiting.\n"));
    return GNUNET_SYSERR;
  }
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_number (cfg, "HOSTLIST", "HTTPPORT",
                                             &port))
    return GNUNET_SYSERR;
  if ((port == 0) || (port > UINT16_MAX))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Invalid port number %llu.  Exiting.\n"), port);
    return GNUNET_SYSERR;
  }

  if (GNUNET_SYSERR ==
      GNUNET_CONFIGURATION_get_value_string (cfg, "HOSTLIST",
                                             "EXTERNAL_DNS_NAME", &hostname))
    hostname = GNUNET_RESOLVER_local_fqdn_get ();

  GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Hostlist service starts on %s:%llu\n"),
              hostname, port);
  if (NULL != hostname)
  {
    size = strlen (hostname);
    if (size + 15 > MAX_URL_LEN)
    {
      GNUNET_break (0);
    }
    else
    {
      GNUNET_asprintf (&hostlist_uri, "http://%s:%u/", hostname,
                       (unsigned int) port);
      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  _("Address to obtain hostlist: `%s'\n"), hostlist_uri);
    }
    GNUNET_free (hostname);
  }
  daemon_handle_v6 = MHD_start_daemon (MHD_USE_IPv6
#if DEBUG_HOSTLIST_SERVER
                                       | MHD_USE_DEBUG
#endif
                                       , (unsigned short) port,
                                       &accept_policy_callback, NULL,
                                       &access_handler_callback, NULL,
                                       MHD_OPTION_CONNECTION_LIMIT,
                                       (unsigned int) 16,
                                       MHD_OPTION_PER_IP_CONNECTION_LIMIT,
                                       (unsigned int) 1,
                                       MHD_OPTION_CONNECTION_TIMEOUT,
                                       (unsigned int) 16,
                                       MHD_OPTION_CONNECTION_MEMORY_LIMIT,
                                       (size_t) (16 * 1024), MHD_OPTION_END);
  daemon_handle_v4 = MHD_start_daemon (MHD_NO_FLAG
#if DEBUG_HOSTLIST_SERVER
                                       | MHD_USE_DEBUG
#endif
                                       , (unsigned short) port,
                                       &accept_policy_callback, NULL,
                                       &access_handler_callback, NULL,
                                       MHD_OPTION_CONNECTION_LIMIT,
                                       (unsigned int) 16,
                                       MHD_OPTION_PER_IP_CONNECTION_LIMIT,
                                       (unsigned int) 1,
                                       MHD_OPTION_CONNECTION_TIMEOUT,
                                       (unsigned int) 16,
                                       MHD_OPTION_CONNECTION_MEMORY_LIMIT,
                                       (size_t) (16 * 1024), MHD_OPTION_END);

  if ((daemon_handle_v6 == NULL) && (daemon_handle_v4 == NULL))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _("Could not start hostlist HTTP server on port %u\n"),
                (unsigned short) port);
    return GNUNET_SYSERR;
  }

  core = co;

  *server_ch = &connect_handler;
  *server_dh = &disconnect_handler;

  if (daemon_handle_v4 != NULL)
    hostlist_task_v4 = prepare_daemon (daemon_handle_v4);
  if (daemon_handle_v6 != NULL)
    hostlist_task_v6 = prepare_daemon (daemon_handle_v6);

  notify = GNUNET_PEERINFO_notify (cfg, process_notify, NULL);

  return GNUNET_OK;
}

/**
 * Stop server offering our hostlist.
 */
void
GNUNET_HOSTLIST_server_stop ()
{
#if DEBUG_HOSTLIST_SERVER
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Hostlist server shutdown\n");
#endif
  if (NULL != notify)
  {
    GNUNET_PEERINFO_notify_cancel (notify);
    notify = NULL;
  }
  if (GNUNET_SCHEDULER_NO_TASK != hostlist_task_v6)
  {
    GNUNET_SCHEDULER_cancel (hostlist_task_v6);
    hostlist_task_v6 = GNUNET_SCHEDULER_NO_TASK;
  }
  if (GNUNET_SCHEDULER_NO_TASK != hostlist_task_v4)
  {
    GNUNET_SCHEDULER_cancel (hostlist_task_v4);
    hostlist_task_v4 = GNUNET_SCHEDULER_NO_TASK;
  }
  if (pitr != NULL)
  {
    GNUNET_PEERINFO_iterate_cancel (pitr);
    pitr = NULL;
  }
  if (NULL != daemon_handle_v4)
  {
    MHD_stop_daemon (daemon_handle_v4);
    daemon_handle_v4 = NULL;
  }
  if (NULL != daemon_handle_v6)
  {
    MHD_stop_daemon (daemon_handle_v6);
    daemon_handle_v6 = NULL;
  }
  if (response != NULL)
  {
    MHD_destroy_response (response);
    response = NULL;
  }
  if (peerinfo != NULL)
  {
    GNUNET_PEERINFO_disconnect (peerinfo);
    peerinfo = NULL;
  }
  cfg = NULL;
  stats = NULL;
  core = NULL;
}

/* end of hostlist-server.c */