[GNUnet-SVN] r8558 - gnunet/src/hostlist

[gnunet]

Author: grothoff
Date: 2009-06-12 23:44:21 -0600 (Fri, 12 Jun 2009)
New Revision: 8558

Added:
   gnunet/src/hostlist/hostlist-client.c
   gnunet/src/hostlist/hostlist-client.h
Modified:
   gnunet/src/hostlist/Makefile.am
   gnunet/src/hostlist/gnunet-daemon-hostlist.c
Log:
client part

Modified: gnunet/src/hostlist/Makefile.am
===================================================================
--- gnunet/src/hostlist/Makefile.am     2009-06-12 19:45:06 UTC (rev 8557)
+++ gnunet/src/hostlist/Makefile.am     2009-06-13 05:44:21 UTC (rev 8558)
@@ -9,14 +9,15 @@
  gnunet-daemon-hostlist
 
 gnunet_daemon_hostlist_SOURCES = \
- gnunet-daemon-hostlist.c
-#
+ gnunet-daemon-hostlist.c \
+ hostlist-client.c hostlist-client.h
 # hostlist-server.c hostlist-server.h 
-# hostlist-client.c hostlist-client.h
+
 gnunet_daemon_hostlist_LDADD = \
   $(top_builddir)/src/core/libgnunetcore.la \
   $(top_builddir)/src/hello/libgnunethello.la \
   $(top_builddir)/src/peerinfo/libgnunetpeerinfo.la \
+  $(top_builddir)/src/statistics/libgnunetstatistics.la \
   $(top_builddir)/src/transport/libgnunettransport.la \
   $(top_builddir)/src/util/libgnunetutil.la \
   -lmicrohttpd \

Modified: gnunet/src/hostlist/gnunet-daemon-hostlist.c
===================================================================
--- gnunet/src/hostlist/gnunet-daemon-hostlist.c        2009-06-12 19:45:06 UTC 
(rev 8557)
+++ gnunet/src/hostlist/gnunet-daemon-hostlist.c        2009-06-13 05:44:21 UTC 
(rev 8558)
@@ -26,12 +26,15 @@
 
 #include <stdlib.h>
 #include "platform.h"
+#include "hostlist-client.h"
+#include "gnunet_core_service.h"
 #include "gnunet_getopt_lib.h"
 #include "gnunet_protocols.h"
 #include "gnunet_program_lib.h"
 #include "gnunet_statistics_service.h"
 #include "gnunet_strings_lib.h"
 #include "gnunet_time_lib.h"
+#include "gnunet_util_lib.h"
 
 
 /**
@@ -51,6 +54,10 @@
  */
 static int provide_hostlist;
 
+/**
+ * Statistics handle.
+ */
+static struct GNUNET_STATISTICS_Handle *stats;
 
 /**
  * gnunet-daemon-hostlist command line options.
@@ -66,8 +73,35 @@
 };
 
 
+static void
+core_init (void *cls,
+          struct GNUNET_CORE_Handle * server,
+          const struct GNUNET_PeerIdentity *
+          my_identity,
+          const struct
+          GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded *
+          publicKey)
+{
+  /* TODO: provide "server" to 'hostlist' module (if applicable) */
+}
 
+
 /**
+ * Last task run during shutdown.  Disconnects us from
+ * the other services.
+ */
+static void
+cleaning_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  if (stats != NULL)
+    {
+      GNUNET_STATISTICS_destroy (stats);
+      stats = NULL;
+    }
+}
+
+
+/**
  * Main function that will be run.
  *
  * @param cls closure
@@ -83,6 +117,13 @@
      const char *cfgfile,
      struct GNUNET_CONFIGURATION_Handle * cfg)
 {
+  GNUNET_CORE_ClientEventHandler ch = NULL;
+  GNUNET_CORE_ClientEventHandler dh = NULL;
+  struct GNUNET_CORE_MessageHandler handlers[] = 
+    {
+      { NULL, 0, 0 }
+    };
+
   if ( (! bootstrapping) &&
        (! learning) &&
        (! provide_hostlist) )
@@ -91,6 +132,7 @@
                  _("None of the functions for the hostlist daemon were 
enabled.  I have no reason to run!\n"));
       return;
     }
+  stats = GNUNET_STATISTICS_create (sched, "hostlist", cfg);
   if (learning)
     {
       // FIXME!
@@ -98,10 +140,8 @@
     }
   if (bootstrapping)
     {
-      // FIXME!
-      // (register handler with core to monitor number of active
-      //  connections; trigger hostlist download via CURL if
-      //  number is low)
+      GNUNET_HOSTLIST_client_start (cfg, sched, stats,
+                                   &ch, &dh);
     }
   if (provide_hostlist)
     {      
@@ -109,6 +149,21 @@
       // (initialize MHD server and run using scheduler;
       //  use peerinfo to gather HELLOs)
     }
+  GNUNET_CORE_connect (sched, cfg,
+                      GNUNET_TIME_UNIT_FOREVER_REL,
+                      NULL,
+                      &core_init,
+                      ch, dh,
+                      NULL,
+                      NULL, GNUNET_NO,
+                      NULL, GNUNET_NO,
+                      handlers);
+  GNUNET_SCHEDULER_add_delayed (sched,
+                                GNUNET_YES,
+                                GNUNET_SCHEDULER_PRIORITY_IDLE,
+                                GNUNET_SCHEDULER_NO_PREREQUISITE_TASK,
+                                GNUNET_TIME_UNIT_FOREVER_REL,
+                                &cleaning_task, NULL);
 }
 
 

Added: gnunet/src/hostlist/hostlist-client.c
===================================================================
--- gnunet/src/hostlist/hostlist-client.c                               (rev 0)
+++ gnunet/src/hostlist/hostlist-client.c       2009-06-13 05:44:21 UTC (rev 
8558)
@@ -0,0 +1,662 @@
+/*
+     This file is part of GNUnet.
+     (C) 2001, 2002, 2003, 2004, 2005, 2006, 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 hostlist/hostlist-client.c
+ * @brief hostlist support.  Downloads HELLOs via HTTP.
+ * @author Christian Grothoff
+ */
+
+#include "platform.h"
+#include "hostlist-client.h"
+#include "gnunet_core_service.h"
+#include "gnunet_hello_lib.h"
+#include "gnunet_transport_service.h"
+#include <curl/curl.h>
+
+/**
+ * Number of connections that we must have to NOT download
+ * hostlists anymore.
+ */
+#define MIN_CONNECTIONS 4
+
+/**
+ * Our configuration.
+ */
+static struct GNUNET_CONFIGURATION_Handle *cfg;
+
+/**
+ * Our scheduler.
+ */
+static struct GNUNET_SCHEDULER_Handle *sched;
+
+/**
+ * Statistics handle.
+ */
+struct GNUNET_STATISTICS_Handle *stats; 
+
+/**
+ * Transport handle.
+ */
+struct GNUNET_TRANSPORT_Handle *transport;
+                       
+/**
+ * Proxy that we are using (can be NULL).
+ */
+static char *proxy;
+
+/**
+ * Buffer for data downloaded via HTTP.
+ */
+static char download_buffer[GNUNET_SERVER_MAX_MESSAGE_SIZE];
+
+/**
+ * Number of bytes valid in 'download_buffer'.
+ */
+static size_t download_pos;
+
+/**
+ * Current URL that we are using.
+ */
+static char *current_url;
+
+/**
+ * Current CURL handle.
+ */
+static CURL *curl;
+
+/**
+ * Current multi-CURL handle.
+ */
+static CURLM *multi;
+
+/**
+ * ID of the current task scheduled.
+ */
+static GNUNET_SCHEDULER_TaskIdentifier current_task;
+
+/**
+ * Amount of time we wait between hostlist downloads.
+ */
+static struct GNUNET_TIME_Relative hostlist_delay;
+
+/**
+ * Set to GNUNET_YES if the current URL had some problems.
+ */ 
+static int bogus_url;
+
+/**
+ * Number of active connections (according to core service).
+ */
+static unsigned int connection_count;
+
+
+/**
+ * Process downloaded bits by calling callback on each HELLO.
+ *
+ * @param ptr buffer with downloaded data
+ * @param size size of a record
+ * @param nmemb number of records downloaded
+ * @param ctx unused
+ * @return number of bytes that were processed (always size*nmemb)
+ */
+static size_t
+download_hostlist_processor (void *ptr, 
+                            size_t size, 
+                            size_t nmemb, 
+                            void *ctx)
+{
+  const char * cbuf = ptr;
+  const struct GNUNET_MessageHeader *msg;
+  size_t total;
+  size_t cpy;
+  size_t left;
+  uint16_t msize;
+
+  total = size * nmemb;
+  if ( (total == 0) || (bogus_url) )
+    return total;  /* ok, no data or bogus data */
+  left = total;
+  while (left > 0)
+    {
+      cpy = GNUNET_MIN (total, GNUNET_SERVER_MAX_MESSAGE_SIZE - download_pos);
+      GNUNET_assert (cpy > 0);
+      memcpy (&download_buffer[download_pos],
+             cbuf,
+             cpy);
+      cbuf += cpy;
+      download_pos += cpy;
+      left -= cpy;
+      if (download_pos < sizeof(struct GNUNET_MessageHeader))
+       break;
+      msg = (const struct GNUNET_MessageHeader *) download_buffer;
+      msize = ntohs(msg->size);
+      if (msize < sizeof(struct GNUNET_MessageHeader))
+       {        
+         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                     _("Invalid `%s' message received from hostlist at 
`%s'\n"),
+                     "HELLO",
+                     current_url); 
+         bogus_url = 1;
+         return total;
+       }
+      if (download_pos < msize)
+       break;
+      if (GNUNET_HELLO_size ((const struct GNUNET_HELLO_Message*)msg) == msize)
+       {
+         GNUNET_TRANSPORT_offer_hello (transport, msg);
+       }
+      else
+       {
+         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                     _("Invalid `%s' message received from hostlist at 
`%s'\n"),
+                     "HELLO",
+                     current_url);
+         bogus_url = 1;
+         return total;
+       }
+      memmove (download_buffer,
+              &download_buffer[msize],
+              download_pos - msize);
+      download_pos -= msize;
+    }
+  return total;
+}
+
+
+/**
+ * Obtain a hostlist URL that we should use.
+ *
+ * @return NULL if there is no URL available
+ */
+static char *
+get_url ()
+{
+  char *servers;
+  char *ret;
+  size_t urls;
+  size_t pos;
+
+  if (GNUNET_OK != 
+      GNUNET_CONFIGURATION_get_value_string (cfg,
+                                            "HOSTLIST",
+                                            "SERVERS",
+                                            &servers))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("No `%s' specified in `%s' configuration, will not 
bootstrap.\n"),
+                 "SERVERS", "HOSTLIST");
+      return NULL;
+    }
+
+  urls = 0;
+  if (strlen (servers) > 0)
+    {
+      urls++;
+      pos = strlen (servers) - 1;
+      while (pos > 0)
+        {
+          if (servers[pos] == ' ')
+            urls++;
+          pos--;
+        }
+    }
+  if (urls == 0)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("No `%s' specified in `%s' configuration, will not 
bootstrap.\n"),
+                 "SERVERS", "HOSTLIST");
+      GNUNET_free (servers);
+      return NULL;
+    }
+
+  urls = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, urls) + 1;
+  pos = strlen (servers) - 1;
+  while (pos > 0)
+    {
+      if (servers[pos] == ' ')
+        {
+          urls--;
+          servers[pos] = '\0';
+        }
+      if (urls == 0)
+        {
+          pos++;
+          break;
+        }
+      pos--;    
+    }
+  ret = GNUNET_strdup (&servers[pos]);
+  GNUNET_free (servers);
+  return ret;
+}
+
+
+#define CURL_EASY_SETOPT(c, a, b) do { ret = curl_easy_setopt(c, a, b); if 
(ret != CURLE_OK) GNUNET_log(GNUNET_ERROR_TYPE_WARNING, _("%s failed at %s:%d: 
`%s'\n"), "curl_easy_setopt", __FILE__, __LINE__, curl_easy_strerror(ret)); } 
while (0);
+
+
+/**
+ * Schedule the background task that will (possibly)
+ * download a hostlist.
+ */
+static void
+schedule_hostlist_task (void);
+
+
+/**
+ * Clean up the state from the task that downloaded the
+ * hostlist and schedule the next task.
+ */
+static void 
+clean_up ()
+{
+  CURLMcode mret;
+
+  if (multi != NULL)
+    {
+      mret = curl_multi_remove_handle (multi, curl);
+      if (mret != CURLM_OK)
+       {
+         GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                     _("%s failed at %s:%d: `%s'\n"),
+                     "curl_multi_remove_handle", __FILE__, __LINE__,
+                     curl_multi_strerror (mret));
+       }
+      mret = curl_multi_cleanup (multi);
+      if (mret != CURLM_OK)
+       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                   _("%s failed at %s:%d: `%s'\n"),
+                   "curl_multi_cleanup", __FILE__, __LINE__,
+                   curl_multi_strerror (mret));
+      multi = NULL;
+    }
+  if (curl != NULL)
+    {
+      curl_easy_cleanup (curl);
+      curl = NULL;
+    }  
+  if (transport != NULL)
+    {
+      GNUNET_TRANSPORT_disconnect (transport);
+      transport = NULL;
+    }
+  GNUNET_free_non_null (current_url);
+  current_url = NULL;
+  schedule_hostlist_task ();
+}
+
+
+/**
+ * Task that is run when we are ready to receive more data from the hostlist
+ * server. 
+ *
+ * @param tc
+ */
+static void
+multi_ready (void *cls,
+            const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  int running;
+  struct CURLMsg *msg;
+  CURLMcode mret;
+
+  if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_TIMEOUT))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("Timeout trying to download hostlist from `%s'\n"),
+                 current_url);
+      clean_up ();
+      return;
+    }
+  do 
+    {
+      running = 0;
+      mret = curl_multi_perform (multi, &running);
+      if (running == 0)
+       {
+         do
+           {
+             msg = curl_multi_info_read (multi, &running);
+             GNUNET_break (msg != NULL);
+             if (msg == NULL)
+               break;
+             switch (msg->msg)
+               {
+               case CURLMSG_DONE:
+                 if (msg->data.result != CURLE_OK)
+                   GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
+                              _("%s failed at %s:%d: `%s'\n"),
+                              "curl_multi_perform", __FILE__,
+                              __LINE__,
+                              curl_easy_strerror (msg->data.result));
+                 break;
+               default:
+                 break;
+               }
+           }
+         while (running > 0);
+       }
+    }
+  while (mret == CURLM_CALL_MULTI_PERFORM);
+  if (mret != CURLM_OK)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                 _("%s failed at %s:%d: `%s'\n"),
+                 "curl_multi_perform", __FILE__, __LINE__,
+                 curl_multi_strerror (mret));
+      clean_up ();
+      return;
+    }
+  clean_up ();
+}
+
+
+/**
+ * Ask CURL for the select set and then schedule the
+ * receiving task with the scheduler.
+ */
+static void
+run_multi () 
+{
+  CURLMcode mret;
+  fd_set rs;
+  fd_set ws;
+  fd_set es;
+  int max;
+  
+  max = 0;
+  FD_ZERO (&rs);
+  FD_ZERO (&ws);
+  FD_ZERO (&es);
+  mret = curl_multi_fdset (multi, &rs, &ws, &es, &max);
+  if (mret != CURLM_OK)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                 _("%s failed at %s:%d: `%s'\n"),
+                 "curl_multi_fdset", __FILE__, __LINE__,
+                 curl_multi_strerror (mret));
+      clean_up ();
+      return;
+    }
+  current_task 
+    = GNUNET_SCHEDULER_add_select (sched,
+                                  GNUNET_NO,
+                                  GNUNET_SCHEDULER_PRIORITY_DEFAULT,
+                                  GNUNET_SCHEDULER_NO_PREREQUISITE_TASK,
+                                  GNUNET_TIME_UNIT_MINUTES,
+                                  max,
+                                  &rs,
+                                  &ws,
+                                  &multi_ready,
+                                  multi);
+}
+
+
+/**
+ * Main function that will download a hostlist and process its
+ * data.
+ */
+static void
+download_hostlist () 
+{
+  CURLcode ret;
+  CURLMcode mret;
+
+  curl = curl_easy_init ();
+  multi = NULL;
+  if (curl == NULL)
+    {
+      GNUNET_break (0);
+      clean_up ();
+      return;
+    }
+  transport = GNUNET_TRANSPORT_connect (sched, cfg, NULL, NULL, NULL, NULL);
+  current_url = get_url ();
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO | GNUNET_ERROR_TYPE_BULK,
+             _("Bootstrapping using hostlist at `%s'.\n"), 
+             current_url);
+
+  if (proxy != NULL)
+    CURL_EASY_SETOPT (curl, CURLOPT_PROXY, proxy);    
+  download_pos = 0;
+  bogus_url = 0;
+  CURL_EASY_SETOPT (curl,
+                   CURLOPT_WRITEFUNCTION, 
+                   &download_hostlist_processor);
+  if (ret != CURLE_OK)
+    {
+      clean_up ();
+      return;
+    }
+  CURL_EASY_SETOPT (curl,
+                   CURLOPT_WRITEDATA, 
+                   NULL);
+  if (ret != CURLE_OK)
+    {
+      clean_up ();
+      return;
+    }
+  CURL_EASY_SETOPT (curl, 
+                   CURLOPT_URL, 
+                   current_url);
+  if (ret != CURLE_OK)
+    {
+      clean_up ();
+      return;
+    }
+  CURL_EASY_SETOPT (curl, 
+                   CURLOPT_FAILONERROR, 
+                   1);
+  CURL_EASY_SETOPT (curl, 
+                   CURLOPT_BUFFERSIZE, 
+                   GNUNET_SERVER_MAX_MESSAGE_SIZE);
+  if (0 == strncmp (current_url, "http", 4))
+    CURL_EASY_SETOPT (curl, CURLOPT_USERAGENT, "GNUnet");
+  CURL_EASY_SETOPT (curl, 
+                   CURLOPT_CONNECTTIMEOUT, 
+                   150L);
+  CURL_EASY_SETOPT (curl,
+                   CURLOPT_NOSIGNAL, 
+                   1);
+  multi = curl_multi_init ();
+  if (multi == NULL)
+    {
+      GNUNET_break (0);
+      clean_up ();
+      return;
+    }
+  mret = curl_multi_add_handle (multi, curl);
+  if (mret != CURLM_OK)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                 _("%s failed at %s:%d: `%s'\n"),
+                 "curl_multi_add_handle", __FILE__, __LINE__,
+                 curl_multi_strerror (mret));
+      mret = curl_multi_cleanup (multi);
+      if (mret != CURLM_OK)
+       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                   _("%s failed at %s:%d: `%s'\n"),
+                   "curl_multi_cleanup", __FILE__, __LINE__,
+                   curl_multi_strerror (mret));
+      multi = NULL;
+      clean_up ();
+      return;
+    }
+  run_multi (multi);
+}  
+
+
+/**
+ * Task that checks if we should try to download a hostlist.
+ * If so, we initiate the download, otherwise we schedule
+ * this task again for a later time.
+ */
+static void
+check_task (void *cls,
+           const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  if (connection_count < MIN_CONNECTIONS)
+    download_hostlist ();
+  else
+    schedule_hostlist_task ();
+}
+
+
+/**
+ * Compute when we should check the next time about downloading
+ * a hostlist; then schedule the task accordingly.
+ */
+static void
+schedule_hostlist_task ()
+{
+  struct GNUNET_TIME_Relative delay;
+
+  delay = hostlist_delay;
+  if (hostlist_delay.value == 0)
+    hostlist_delay = GNUNET_TIME_UNIT_SECONDS;
+  else
+    hostlist_delay = GNUNET_TIME_relative_multiply (hostlist_delay, 2);
+  if (hostlist_delay.value > GNUNET_TIME_UNIT_HOURS.value * connection_count)
+    hostlist_delay = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_DAYS,
+                                                   connection_count);
+  GNUNET_STATISTICS_set (stats,
+                        gettext_noop("Minimum time between hostlist 
downloads"),
+                        hostlist_delay.value,
+                        GNUNET_YES);
+  current_task = GNUNET_SCHEDULER_add_delayed (sched,
+                                              GNUNET_NO,
+                                              GNUNET_SCHEDULER_PRIORITY_IDLE,
+                                              
GNUNET_SCHEDULER_NO_PREREQUISITE_TASK,
+                                              delay,
+                                              &check_task,
+                                              NULL);
+}
+
+
+/**
+ * Method called whenever a given peer connects.
+ *
+ * @param cls closure
+ * @param peer peer identity this notification is about
+ */
+static void
+connect_handler (void *cls,
+                const struct
+                GNUNET_PeerIdentity * peer)
+{
+  connection_count++;
+}
+
+
+/**
+ * Method called whenever a given peer connects.
+ *
+ * @param cls closure
+ * @param peer peer identity this notification is about
+ */
+static void
+disconnect_handler (void *cls,
+                   const struct
+                   GNUNET_PeerIdentity * peer)
+{
+  connection_count--;
+}
+
+
+/**
+ * Continuation called by the statistics code once 
+ * we go the stat.  Initiates hostlist download scheduling.
+ *
+ * @param cls closure
+ * @param success GNUNET_OK if statistics were
+ *        successfully obtained, GNUNET_SYSERR if not.
+ */
+static void
+primary_task (void *cls, int success)
+{
+  schedule_hostlist_task ();
+}
+
+
+static int
+process_stat (void *cls,
+             const char *subsystem,
+             const char *name,
+             unsigned long long value,
+             int is_persistent)
+{
+  hostlist_delay.value = (uint64_t) value;
+  return GNUNET_OK;
+}
+
+
+/**
+ * Start downloading hostlists from hostlist servers as necessary.
+ */
+int
+GNUNET_HOSTLIST_client_start (struct GNUNET_CONFIGURATION_Handle *c,
+                             struct GNUNET_SCHEDULER_Handle *s,
+                             struct GNUNET_STATISTICS_Handle *st,
+                             GNUNET_CORE_ClientEventHandler *ch,
+                             GNUNET_CORE_ClientEventHandler *dh)
+{
+  if (0 != curl_global_init (CURL_GLOBAL_WIN32))
+    {
+      GNUNET_break (0);
+      return GNUNET_SYSERR;
+    }
+  cfg = c;
+  sched = s;
+  stats = st;
+  proxy = NULL;
+  GNUNET_CONFIGURATION_get_value_string (cfg,
+                                        "HOSTLIST",
+                                        "HTTP-PROXY", 
+                                        &proxy);
+  *ch = &connect_handler;
+  *dh = &disconnect_handler;
+  GNUNET_STATISTICS_get (stats,
+                        "hostlist",
+                        gettext_noop("Minimum time between hostlist 
downloads"),
+                        GNUNET_TIME_UNIT_MINUTES,
+                        &primary_task,
+                        &process_stat,
+                        NULL);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Stop downloading hostlists from hostlist servers as necessary.
+ */
+void
+GNUNET_HOSTLIST_client_stop ()
+{
+  GNUNET_SCHEDULER_cancel (sched,
+                          current_task);
+  GNUNET_free_non_null (proxy);
+  proxy = NULL;
+  if (sched != NULL)
+    curl_global_cleanup ();
+  cfg = NULL;
+  sched = NULL;
+}
+
+/* end of hostlist-client.c */

Added: gnunet/src/hostlist/hostlist-client.h
===================================================================
--- gnunet/src/hostlist/hostlist-client.h                               (rev 0)
+++ gnunet/src/hostlist/hostlist-client.h       2009-06-13 05:44:21 UTC (rev 
8558)
@@ -0,0 +1,58 @@
+/*
+     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 hostlist/hostlist-client.h
+ * @brief hostlist support.  Downloads HELLOs via HTTP.
+ * @author Christian Grothoff
+ */
+
+#ifndef HOSTLIST_CLIENT_H
+#define HOSTLIST_CLIENT_H
+
+#include "gnunet_core_service.h"
+#include "gnunet_statistics_service.h"
+#include "gnunet_util_lib.h"
+
+
+/**
+ * Start downloading hostlists from hostlist servers as necessary.
+ *
+ * @param ch set to handler for connect notifications
+ * @param dh set to handler for disconnect notifications
+ * @return GNUNET_OK on success
+ */
+int
+GNUNET_HOSTLIST_client_start (struct GNUNET_CONFIGURATION_Handle *c,
+                             struct GNUNET_SCHEDULER_Handle *s,
+                             struct GNUNET_STATISTICS_Handle *st,
+                             GNUNET_CORE_ClientEventHandler *ch,
+                             GNUNET_CORE_ClientEventHandler *dh);
+
+
+/**
+ * Stop downloading hostlists from hostlist servers as necessary.
+ */
+void
+GNUNET_HOSTLIST_client_stop (void);
+
+
+#endif
+/* end of hostlist-client.h */