X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Fpeerinfo%2Fpeerinfo_api.c;h=faa56e908b54e43b03acde434c13bbb6522210e5;hb=bcb48ad6fa905f02703fcbd53d74326c51730afc;hp=5531ede977d8425fa3e8f000ef7b10c8d8ee0d7e;hpb=98ea57dd2236542414e52792672d8563c8ca4294;p=oweals%2Fgnunet.git

diff --git a/src/peerinfo/peerinfo_api.c b/src/peerinfo/peerinfo_api.c
index 5531ede97..faa56e908 100644
--- a/src/peerinfo/peerinfo_api.c
+++ b/src/peerinfo/peerinfo_api.c
@@ -1,10 +1,10 @@
 /*
      This file is part of GNUnet.
-     (C) 2001, 2002, 2004, 2005, 2007, 2009 Christian Grothoff (and other contributing authors)
+     (C) 2001, 2002, 2004, 2005, 2007, 2009, 2010, 2012 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
+     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
@@ -25,547 +25,769 @@
  */
 #include "platform.h"
 #include "gnunet_client_lib.h"
+#include "gnunet_container_lib.h"
 #include "gnunet_peerinfo_service.h"
 #include "gnunet_protocols.h"
 #include "gnunet_time_lib.h"
 #include "peerinfo.h"
 
-#define ADD_PEER_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 30)
+#define LOG(kind,...) GNUNET_log_from (kind, "peerinfo-api",__VA_ARGS__)
 
 
-struct CAFContext
+/**
+ * Entry in the transmission queue to PEERINFO service.  We use
+ * the same structure for queueing 'iteration' requests and
+ * actual 'add' messages.
+ */
+struct GNUNET_PEERINFO_AddContext
 {
-  struct GNUNET_CLIENT_Connection *client;
-  struct GNUNET_MessageHeader *msg;
-};
+  /**
+   * This is a linked list.
+   */
+  struct GNUNET_PEERINFO_AddContext *next;
 
+  /**
+   * This is a linked list.
+   */
+  struct GNUNET_PEERINFO_AddContext *prev;
 
-static size_t
-copy_and_free (void *cls, size_t size, void *buf)
-{
-  struct CAFContext *cc = cls;
-  struct GNUNET_MessageHeader *msg = cc->msg;
-  uint16_t msize;
+  /**
+   * Handle to the PEERINFO service.
+   */
+  struct GNUNET_PEERINFO_Handle *h;
 
-  if (buf == NULL)
-    {
-#if DEBUG_PEERINFO
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _
-                  ("Failed to transmit message of type %u to `%s' service.\n"),
-                  ntohs (msg->type), "peerinfo");
-#endif
-      GNUNET_free (msg);
-      GNUNET_CLIENT_disconnect (cc->client);
-      GNUNET_free (cc);
-      return 0;
-    }
-  msize = ntohs (msg->size);
-  GNUNET_assert (size >= msize);
-  memcpy (buf, msg, msize);
-  GNUNET_free (msg);
-  GNUNET_CLIENT_disconnect (cc->client);
-  GNUNET_free (cc);
-  return msize;
-}
+  /**
+   * Function to call after request has been transmitted, or NULL.
+   */
+  GNUNET_PEERINFO_Continuation cont;
 
+  /**
+   * Closure for 'cont'.
+   */
+  void *cont_cls;
 
+  /**
+   * Number of bytes of the request message (follows after this struct).
+   */
+  size_t size;
 
-/**
- * Add a host to the persistent list.
- *
- * @param cfg configuration to use
- * @param sched scheduler to use
- * @param peer identity of the peer
- * @param hello the verified (!) HELLO message
- */
-void
-GNUNET_PEERINFO_add_peer (const struct GNUNET_CONFIGURATION_Handle *cfg,
-                          struct GNUNET_SCHEDULER_Handle *sched,
-                          const struct GNUNET_PeerIdentity *peer,
-                          const struct GNUNET_HELLO_Message *hello)
-{
-  struct GNUNET_CLIENT_Connection *client;
-  struct PeerAddMessage *pam;
-  uint16_t hs;
-  struct CAFContext *cc;
-
-#if DEBUG_PEERINFO
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-	      "Adding peer `%s' to peerinfo database\n",
-	      GNUNET_i2s(peer));
-#endif
-  client = GNUNET_CLIENT_connect (sched, "peerinfo", cfg);
-  if (client == NULL)
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("Could not connect to `%s' service.\n"), "peerinfo");
-      return;
-    }
-  hs = GNUNET_HELLO_size (hello);
-#if DEBUG_PEERINFO
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-	      "Size of `%s' is %u bytes\n",
-	      "HELLO",
-	      (unsigned int) GNUNET_HELLO_size (hello));
-#endif  
-  pam = GNUNET_malloc (sizeof (struct PeerAddMessage) + hs);
-  pam->header.size = htons (hs + sizeof (struct PeerAddMessage));
-  pam->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_ADD);
-  memcpy (&pam->peer, peer, sizeof (struct GNUNET_PeerIdentity));
-  memcpy (&pam[1], hello, hs);
-  cc = GNUNET_malloc (sizeof (struct CAFContext));
-  cc->client = client;
-  cc->msg = &pam->header;
-  GNUNET_CLIENT_notify_transmit_ready (client,
-                                       ntohs (pam->header.size),
-                                       ADD_PEER_TIMEOUT, 
-				       GNUNET_NO,
-				       &copy_and_free, cc);
-}
+};
 
 
 /**
- * Context for the info handler.
+ * Context for an iteration request.
  */
 struct GNUNET_PEERINFO_IteratorContext
 {
 
   /**
-   * Our connection to the PEERINFO service.
+   * Kept in a DLL.
    */
-  struct GNUNET_CLIENT_Connection *client;
+  struct GNUNET_PEERINFO_IteratorContext *next;
+
+  /**
+   * Kept in a DLL.
+   */
+  struct GNUNET_PEERINFO_IteratorContext *prev;
+
+  /**
+   * Handle to the PEERINFO service.
+   */
+  struct GNUNET_PEERINFO_Handle *h;
 
   /**
-   * Function to call with information.
+   * Function to call with the results.
    */
   GNUNET_PEERINFO_Processor callback;
 
   /**
-   * Closure for callback.
+   * Closure for 'callback'.
    */
   void *callback_cls;
 
   /**
-   * When should we time out?
+   * Our entry in the transmission queue.
+   */
+  struct GNUNET_PEERINFO_AddContext *ac;
+
+  /**
+   * Task responsible for timeout.
+   */
+  GNUNET_SCHEDULER_TaskIdentifier timeout_task;
+
+  /**
+   * Timeout for the operation.
    */
   struct GNUNET_TIME_Absolute timeout;
 
+  /**
+   * Peer we are interested in (only valid if iteration was restricted to one peer).
+   */
+  struct GNUNET_PeerIdentity peer;
+
+  /**
+   * Is 'peer' set?
+   */
+  int have_peer;
+
+  /**
+   * Set to GNUNET_YES if we are currently receiving replies from the
+   * service.
+   */
+  int request_transmitted;
+
 };
 
 
 /**
- * Type of a function to call when we receive a message
- * from the service.
- *
- * @param cls closure
- * @param msg message received, NULL on timeout or fatal error
+ * Handle to the peerinfo service.
  */
-static void
-info_handler (void *cls, const struct GNUNET_MessageHeader *msg)
+struct GNUNET_PEERINFO_Handle
 {
-  struct GNUNET_PEERINFO_IteratorContext *ic = cls;
-  const struct InfoMessage *im;
-  const struct GNUNET_HELLO_Message *hello;
-  uint16_t ms;
+  /**
+   * Our configuration.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
 
-  if (msg == NULL)
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("Failed to receive response from `%s' service.\n"),
-                  "peerinfo");
-      ic->callback (ic->callback_cls, NULL, NULL, 1);
-      GNUNET_CLIENT_disconnect (ic->client);
-      GNUNET_free (ic);
-      return;
-    }
-  if (ntohs (msg->type) == GNUNET_MESSAGE_TYPE_PEERINFO_INFO_END)
-    {
-#if DEBUG_PEERINFO
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-		  "Received end of list of peers from peerinfo database\n");
-#endif
-      ic->callback (ic->callback_cls, NULL, NULL, 0);
-      GNUNET_CLIENT_disconnect (ic->client);
-      GNUNET_free (ic);
-      return;
-    }
-  ms = ntohs (msg->size);
-  if ((ms < sizeof (struct InfoMessage)) ||
-      (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_PEERINFO_INFO))
-    {
-      GNUNET_break (0);
-      ic->callback (ic->callback_cls, NULL, NULL, 2);
-      GNUNET_CLIENT_disconnect (ic->client);
-      GNUNET_free (ic);
-      return;
-    }
-  im = (const struct InfoMessage *) msg;
-  hello = NULL;
-  if (ms > sizeof (struct InfoMessage) + sizeof (struct GNUNET_MessageHeader))
-    {
-      hello = (const struct GNUNET_HELLO_Message *) &im[1];
-      if (ms != sizeof (struct InfoMessage) + GNUNET_HELLO_size (hello))
-        {
-          GNUNET_break (0);
-          ic->callback (ic->callback_cls, NULL, NULL, 2);
-          GNUNET_CLIENT_disconnect (ic->client);
-          GNUNET_free (ic);
-          return;
-        }
-    }
-#if DEBUG_PEERINFO
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-	      "Received information about peer `%s' from peerinfo database\n",
-	      GNUNET_i2s (&im->peer));
-#endif
-#if DEBUG_PEERINFO
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-	      "Size of `%s' is %u bytes\n",
-	      "HELLO",
-	      (hello == NULL) ? 0 : (unsigned int) GNUNET_HELLO_size (hello));
-#endif  
-  ic->callback (ic->callback_cls, &im->peer, hello, ntohl (im->trust));
-  GNUNET_CLIENT_receive (ic->client,
-                         &info_handler,
-                         ic,
-                         GNUNET_TIME_absolute_get_remaining (ic->timeout));
-}
+  /**
+   * Connection to the service.
+   */
+  struct GNUNET_CLIENT_Connection *client;
+
+  /**
+   * Head of transmission queue.
+   */
+  struct GNUNET_PEERINFO_AddContext *ac_head;
+
+  /**
+   * Tail of transmission queue.
+   */
+  struct GNUNET_PEERINFO_AddContext *ac_tail;
+
+  /**
+   * Handle for the current transmission request, or NULL if none is pending.
+   */
+  struct GNUNET_CLIENT_TransmitHandle *th;
+
+  /**
+   * Head of iterator DLL.
+   */
+  struct GNUNET_PEERINFO_IteratorContext *ic_head;
+
+  /**
+   * Tail of iterator DLL.
+   */
+  struct GNUNET_PEERINFO_IteratorContext *ic_tail;
+
+  /**
+   * ID for a reconnect task.
+   */
+  GNUNET_SCHEDULER_TaskIdentifier r_task;
+
+  /**
+   * Are we now receiving?
+   */
+  int in_receive;
+
+};
 
 
 /**
- * Call a method for each known matching host and change
- * its trust value.  The method will be invoked once for
- * each host and then finally once with a NULL pointer.
- * Note that the last call can be triggered by timeout or
- * by simply being done; however, the trust argument will
- * be set to zero if we are done and to 1 if we timed out.
+ * Connect to the peerinfo service.
  *
  * @param cfg configuration to use
- * @param sched scheduler to use
- * @param peer restrict iteration to this peer only (can be NULL)
- * @param trust_delta how much to change the trust in all matching peers
- * @param timeout how long to wait until timing out
- * @param callback the method to call for each peer
- * @param callback_cls closure for callback
- * @return NULL on error, otherwise an iterator context
+ * @return NULL on error (configuration related, actual connection
+ *         establishment may happen asynchronously).
  */
-struct GNUNET_PEERINFO_IteratorContext *
-GNUNET_PEERINFO_iterate (const struct GNUNET_CONFIGURATION_Handle *cfg,
-                         struct GNUNET_SCHEDULER_Handle *sched,
-                         const struct GNUNET_PeerIdentity *peer,
-                         int trust_delta,
-                         struct GNUNET_TIME_Relative timeout,
-                         GNUNET_PEERINFO_Processor callback,
-                         void *callback_cls)
+struct GNUNET_PEERINFO_Handle *
+GNUNET_PEERINFO_connect (const struct GNUNET_CONFIGURATION_Handle *cfg)
 {
-  struct GNUNET_CLIENT_Connection *client;
-  struct ListAllPeersMessage *lapm;
-  struct ListPeerMessage *lpm;
-  struct GNUNET_PEERINFO_IteratorContext *ihc;
+  struct GNUNET_PEERINFO_Handle *h;
 
-  client = GNUNET_CLIENT_connect (sched, "peerinfo", cfg);
-  if (client == NULL)
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("Could not connect to `%s' service.\n"), "peerinfo");
-      return NULL;
-    }
-#if DEBUG_PEERINFO
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-	      "Requesting list of peers from peerinfo database\n");
-#endif
-  if (peer == NULL)
-    {
-      ihc = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_IteratorContext) +
-			   sizeof (struct ListAllPeersMessage));
-      lapm = (struct ListAllPeersMessage *) &ihc[1];
-      lapm->header.size = htons (sizeof (struct ListAllPeersMessage));
-      lapm->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_GET_ALL);
-      lapm->trust_change = htonl (trust_delta);
-    }
-  else
-    {
-      ihc = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_IteratorContext) +
-			   sizeof (struct ListPeerMessage));
-      lpm = (struct ListPeerMessage *) &ihc[1];
-      lpm->header.size = htons (sizeof (struct ListPeerMessage));
-      lpm->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_GET);
-      lpm->trust_change = htonl (trust_delta);
-      memcpy (&lpm->peer, peer, sizeof (struct GNUNET_PeerIdentity));
-    }
-  ihc->client = client;
-  ihc->callback = callback;
-  ihc->callback_cls = callback_cls;
-  ihc->timeout = GNUNET_TIME_relative_to_absolute (timeout);
-  if (GNUNET_OK != 
-      GNUNET_CLIENT_transmit_and_get_response (client,
-					       (const struct GNUNET_MessageHeader*) &ihc[1],
-					       timeout,
-					       GNUNET_YES,
-					       &info_handler,
-					       ihc))
-    {
-      GNUNET_break (0);
-      GNUNET_CLIENT_disconnect (ihc->client);
-      GNUNET_free (ihc);
-      return NULL;
-    }
-  return ihc;
+  h = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_Handle));
+  h->client = GNUNET_CLIENT_connect ("peerinfo", cfg);
+  h->cfg = cfg;
+  return h;
 }
 
 
 /**
- * Cancel an iteration over peer information.
+ * Disconnect from the peerinfo service.  Note that all iterators must
+ * have completed or have been cancelled by the time this function is
+ * called (otherwise, calling this function is a serious error).
+ * Furthermore, if 'GNUNET_PEERINFO_add_peer' operations are still
+ * pending, they will be cancelled silently on disconnect.
  *
- * @param ic context of the iterator to cancel
+ * @param h handle to disconnect
  */
 void
-GNUNET_PEERINFO_iterate_cancel (struct GNUNET_PEERINFO_IteratorContext *ic)
+GNUNET_PEERINFO_disconnect (struct GNUNET_PEERINFO_Handle *h)
 {
-  GNUNET_CLIENT_disconnect (ic->client);
-  GNUNET_free (ic);
+  struct GNUNET_PEERINFO_AddContext *ac;
+  struct GNUNET_PEERINFO_IteratorContext *ic;
+
+  while (NULL != (ic = h->ic_head))
+  {
+    GNUNET_break (GNUNET_YES == ic->request_transmitted);
+    ic->request_transmitted = GNUNET_NO;
+    GNUNET_PEERINFO_iterate_cancel (ic);
+  }
+  while (NULL != (ac = h->ac_head))
+  {
+    GNUNET_CONTAINER_DLL_remove (h->ac_head, h->ac_tail, ac);
+    if (NULL != ac->cont)
+      ac->cont (ac->cont_cls, _("aborted due to explicit disconnect request"));
+    GNUNET_free (ac);
+  }
+  if (NULL != h->th)
+  {
+    GNUNET_CLIENT_notify_transmit_ready_cancel (h->th);
+    h->th = NULL;
+  }
+  if (NULL != h->client)
+  {
+    GNUNET_CLIENT_disconnect (h->client);
+    h->client = NULL;
+  }
+  if (GNUNET_SCHEDULER_NO_TASK != h->r_task)
+  {
+    GNUNET_SCHEDULER_cancel (h->r_task);
+    h->r_task = GNUNET_SCHEDULER_NO_TASK;
+  }
+  GNUNET_free (h);
 }
 
 
 /**
- * Context for the info handler.
+ * Check if we have a request pending in the transmission queue and are
+ * able to transmit it right now.  If so, schedule transmission.
+ *
+ * @param h handle to the service
  */
-struct GNUNET_PEERINFO_NotifyContext
-{
+static void
+trigger_transmit (struct GNUNET_PEERINFO_Handle *h);
 
-  /**
-   * Our connection to the PEERINFO service.
-   */
-  struct GNUNET_CLIENT_Connection *client;
 
-  /**
-   * Function to call with information.
-   */
-  GNUNET_PEERINFO_Processor callback;
+/**
+ * Close the existing connection to PEERINFO and reconnect.
+ *
+ * @param h handle to the service
+ */
+static void
+reconnect (struct GNUNET_PEERINFO_Handle *h);
 
-  /**
-   * Closure for callback.
-   */
-  void *callback_cls;
 
-  /**
-   * Handle to our initial request for message transmission to
-   * the peerinfo service.
-   */
-  struct GNUNET_CLIENT_TransmitHandle *init;
-
-  /**
-   * Configuration.
-   */
-  const struct GNUNET_CONFIGURATION_Handle *cfg;
+/**
+ * Task scheduled to re-try connecting to the peerinfo service.
+ *
+ * @param cls the 'struct GNUNET_PEERINFO_Handle'
+ * @param tc scheduler context
+ */
+static void
+reconnect_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct GNUNET_PEERINFO_Handle *h = cls;
 
-  /**
-   * Scheduler.
-   */
-  struct GNUNET_SCHEDULER_Handle *sched;
-};
+  h->r_task = GNUNET_SCHEDULER_NO_TASK;
+  reconnect (h);
+}
 
 
 /**
- * Send a request to the peerinfo service to start being
- * notified about all changes to peer information.
+ * Close the existing connection to PEERINFO and reconnect.
  *
- * @param nc our context
+ * @param h handle to the service
  */
 static void
-request_notifications (struct GNUNET_PEERINFO_NotifyContext *nc);
+reconnect (struct GNUNET_PEERINFO_Handle *h)
+{
+  if (GNUNET_SCHEDULER_NO_TASK != h->r_task)
+  {
+    GNUNET_SCHEDULER_cancel (h->r_task);
+    h->r_task = GNUNET_SCHEDULER_NO_TASK;
+  }
+  if (NULL != h->th)
+  {
+    GNUNET_CLIENT_notify_transmit_ready_cancel (h->th);
+    h->th = NULL;
+  }
+  if (NULL != h->client)
+  {
+    GNUNET_CLIENT_disconnect (h->client);
+    h->client = NULL;
+  }
+  h->in_receive = GNUNET_NO;
+  h->client = GNUNET_CLIENT_connect ("peerinfo", h->cfg);
+  if (NULL == h->client)
+  {
+    h->r_task =
+        GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS, &reconnect_task,
+                                      h);
+    return;
+  }
+  trigger_transmit (h);
+}
 
 
 /**
- * Read notifications from the client handle and pass them
- * to the callback.
+ * Transmit the request at the head of the transmission queue
+ * and trigger continuation (if any).
  *
- * @param nc our context
+ * @param cls the 'struct GNUNET_PEERINFO_Handle' (with the queue)
+ * @param size size of the buffer (0 on error)
+ * @param buf where to copy the message
+ * @return number of bytes copied to buf
+ */
+static size_t
+do_transmit (void *cls, size_t size, void *buf)
+{
+  struct GNUNET_PEERINFO_Handle *h = cls;
+  struct GNUNET_PEERINFO_AddContext *ac = h->ac_head;
+  size_t ret;
+
+  h->th = NULL;
+  if (NULL == ac)
+    return 0; /* request was cancelled in the meantime */
+  if (NULL == buf)
+  {
+    /* peerinfo service died */
+    LOG (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
+         "Failed to transmit message to `%s' service.\n", "PEERINFO");
+    GNUNET_CONTAINER_DLL_remove (h->ac_head, h->ac_tail, ac);
+    reconnect (h);
+    if (NULL != ac->cont)
+      ac->cont (ac->cont_cls, _("failed to transmit request (service down?)"));
+    GNUNET_free (ac);
+    return 0;
+  }
+  ret = ac->size;
+  if (size < ret)
+  {
+    /* change in head of queue (i.e. cancel + add), try again */
+    trigger_transmit (h);
+    return 0;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Transmitting request of size %u to `%s' service.\n", ret, "PEERINFO");
+  memcpy (buf, &ac[1], ret);
+  GNUNET_CONTAINER_DLL_remove (h->ac_head, h->ac_tail, ac);
+  trigger_transmit (h);
+  if (NULL != ac->cont)
+    ac->cont (ac->cont_cls, NULL);
+  GNUNET_free (ac);
+  return ret;
+}
+
+
+/**
+ * Check if we have a request pending in the transmission queue and are
+ * able to transmit it right now.  If so, schedule transmission.
+ *
+ * @param h handle to the service
  */
 static void
-receive_notifications (struct GNUNET_PEERINFO_NotifyContext *nc);
+trigger_transmit (struct GNUNET_PEERINFO_Handle *h)
+{
+  struct GNUNET_PEERINFO_AddContext *ac;
+
+  if (NULL == (ac = h->ac_head))
+    return; /* no requests queued */
+  if (NULL != h->th)
+    return; /* request already pending */
+  if (NULL == h->client)
+  {
+    /* disconnected, try to reconnect */
+    reconnect (h);
+    return;
+  }
+  h->th =
+    GNUNET_CLIENT_notify_transmit_ready (h->client, ac->size,
+					 GNUNET_TIME_UNIT_FOREVER_REL,
+					 GNUNET_YES,
+					 &do_transmit, h);
+}
+
+
+/**
+ * Add a host to the persistent list.  This method operates in
+ * semi-reliable mode: if the transmission is not completed by
+ * the time 'GNUNET_PEERINFO_disconnect' is called, it will be
+ * aborted.  Furthermore, if a second HELLO is added for the
+ * same peer before the first one was transmitted, PEERINFO may
+ * merge the two HELLOs prior to transmission to the service.
+ *
+ * @param h handle to the peerinfo service
+ * @param hello the verified (!) HELLO message
+ * @param cont continuation to call when done, NULL is allowed
+ * @param cont_cls closure for 'cont'
+ * @return handle to cancel add operation; all pending
+ *         'add' operations will be cancelled automatically
+ *        on disconnect, so it is not necessary to keep this
+ *        handle (unless 'cont' is NULL and at some point
+ *        calling 'cont' must be prevented)
+ */
+struct GNUNET_PEERINFO_AddContext *
+GNUNET_PEERINFO_add_peer (struct GNUNET_PEERINFO_Handle *h,
+                          const struct GNUNET_HELLO_Message *hello,
+			  GNUNET_PEERINFO_Continuation cont,
+			  void *cont_cls)
+{
+  uint16_t hs = GNUNET_HELLO_size (hello);
+  struct GNUNET_PEERINFO_AddContext *ac;
+  struct GNUNET_PeerIdentity peer;
+
+  GNUNET_assert (GNUNET_OK == GNUNET_HELLO_get_id (hello, &peer));
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Adding peer `%s' to PEERINFO database (%u bytes of `%s')\n",
+       GNUNET_i2s (&peer), hs, "HELLO");
+  ac = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_AddContext) + hs);
+  ac->h = h;
+  ac->size = hs;
+  ac->cont = cont;
+  ac->cont_cls = cont_cls;
+  memcpy (&ac[1], hello, hs);
+  GNUNET_CONTAINER_DLL_insert_tail (h->ac_head, h->ac_tail, ac);
+  trigger_transmit (h);
+  return ac;
+}
+
+
+/**
+ * Cancel pending 'add' operation.  Must only be called before
+ * either 'cont' or 'GNUNET_PEERINFO_disconnect' are invoked.
+ *
+ * @param ac handle for the add operation to cancel
+ */
+void 
+GNUNET_PEERINFO_add_peer_cancel (struct GNUNET_PEERINFO_AddContext *ac)
+{
+  struct GNUNET_PEERINFO_Handle *h = ac->h;
+
+  GNUNET_CONTAINER_DLL_remove (h->ac_head, h->ac_tail, ac);
+  GNUNET_free (ac);
+}
 
 
 /**
- * Receive a peerinfo information message, process it and
- * go for more.
+ * Type of a function to call when we receive a message from the
+ * service.  Call the iterator with the result and (if applicable)
+ * continue to receive more messages or trigger processing the next
+ * event (if applicable).
  *
  * @param cls closure
  * @param msg message received, NULL on timeout or fatal error
  */
 static void
-process_notification (void *cls,
-		      const struct
-		      GNUNET_MessageHeader * msg)
+peerinfo_handler (void *cls, const struct GNUNET_MessageHeader *msg)
 {
-  struct GNUNET_PEERINFO_NotifyContext *nc = cls;
+  struct GNUNET_PEERINFO_Handle *h = cls;
+  struct GNUNET_PEERINFO_IteratorContext *ic = h->ic_head;
   const struct InfoMessage *im;
   const struct GNUNET_HELLO_Message *hello;
+  GNUNET_PEERINFO_Processor cb;
+  struct GNUNET_PeerIdentity id;
+  void *cb_cls;
   uint16_t ms;
 
-  if (msg == NULL)
+  h->in_receive = GNUNET_NO;
+  if (NULL == msg)
+  {
+    /* peerinfo service died, signal error */
+    if (NULL != ic)
     {
-      GNUNET_CLIENT_disconnect (nc->client);
-      nc->client = GNUNET_CLIENT_connect (nc->sched, "peerinfo", nc->cfg);
-      request_notifications (nc);
-      return;
+      cb = ic->callback;
+      cb_cls = ic->callback_cls;
+      GNUNET_PEERINFO_iterate_cancel (ic);
+    }
+    else
+    {
+      cb = NULL;
     }
+    reconnect (h);
+    if (NULL != cb)
+      cb (cb_cls, NULL, NULL,
+	  _("Failed to receive response from `PEERINFO' service."));
+    return;
+  }
+  if (NULL == ic)
+  {
+    /* didn't expect a response, reconnect */
+    reconnect (h);
+    return;
+  }
+  ic->request_transmitted = GNUNET_NO;
+  cb = ic->callback;
+  cb_cls = ic->callback_cls;
+  if (GNUNET_MESSAGE_TYPE_PEERINFO_INFO_END == ntohs (msg->type))
+  {
+    /* normal end of list of peers, signal end, process next pending request */
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Received end of list of peers from `%s' service\n", "PEERINFO");
+    GNUNET_PEERINFO_iterate_cancel (ic);
+    trigger_transmit (h);
+    if ( (GNUNET_NO == h->in_receive) &&
+	 (NULL != h->ic_head) )
+    {
+      h->in_receive = GNUNET_YES;
+      GNUNET_CLIENT_receive (h->client, &peerinfo_handler, h,
+			     GNUNET_TIME_absolute_get_remaining (h->ic_head->timeout));
+    }    
+    if (NULL != cb)
+      cb (cb_cls, NULL, NULL, NULL);
+    return;
+  }
+
   ms = ntohs (msg->size);
   if ((ms < sizeof (struct InfoMessage)) ||
       (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_PEERINFO_INFO))
+  {
+    /* malformed message */
+    GNUNET_break (0);
+    GNUNET_PEERINFO_iterate_cancel (ic);
+    reconnect (h);
+    if (NULL != cb)
+      cb (cb_cls, NULL, NULL,
+	  _("Received invalid message from `PEERINFO' service."));
+    return;
+  }
+  im = (const struct InfoMessage *) msg;
+  GNUNET_break (0 == ntohl (im->reserved));
+  if ( (GNUNET_YES == ic->have_peer) &&
+       (0 != memcmp (&ic->peer, &im->peer, sizeof (struct GNUNET_PeerIdentity))) )
+  {
+    /* bogus message (from a different iteration call?); out of sequence! */
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+         "Received HELLO for peer `%s', expected peer `%s'\n",
+	 GNUNET_h2s (&im->peer.hashPubKey),
+	 GNUNET_i2s (&ic->peer));
+    
+    GNUNET_break (0);
+    GNUNET_PEERINFO_iterate_cancel (ic);
+    reconnect (h);
+    if (NULL != cb)      
+      cb (cb_cls, NULL, NULL,
+	  _("Received invalid message from `PEERINFO' service."));
+    return;
+  }
+  hello = NULL;
+  if (ms > sizeof (struct InfoMessage) + sizeof (struct GNUNET_MessageHeader))
+  {
+    hello = (const struct GNUNET_HELLO_Message *) &im[1];
+    if (ms != sizeof (struct InfoMessage) + GNUNET_HELLO_size (hello))
     {
+      /* malformed message */
       GNUNET_break (0);
-      GNUNET_CLIENT_disconnect (nc->client);
-      nc->client = GNUNET_CLIENT_connect (nc->sched, "peerinfo", nc->cfg);
-      request_notifications (nc);
+      GNUNET_PEERINFO_iterate_cancel (ic);
+      reconnect (h);
+      if (NULL != cb)      
+        cb (cb_cls, NULL, NULL,
+	    _("Received invalid message from `PEERINFO' service."));
       return;
     }
-  im = (const struct InfoMessage *) msg;
-  hello = NULL;
-  if (ms > sizeof (struct InfoMessage) + sizeof (struct GNUNET_MessageHeader))
+    if (GNUNET_OK != GNUNET_HELLO_get_id (hello, &id))
     {
-      hello = (const struct GNUNET_HELLO_Message *) &im[1];
-      if (ms != sizeof (struct InfoMessage) + GNUNET_HELLO_size (hello))
-        {
-          GNUNET_break (0);
-	  GNUNET_CLIENT_disconnect (nc->client);
-	  nc->client = GNUNET_CLIENT_connect (nc->sched, "peerinfo", nc->cfg);
-	  request_notifications (nc);
-          return;
-        }
+      /* malformed message */
+      GNUNET_break (0);
+      GNUNET_PEERINFO_iterate_cancel (ic);
+      reconnect (h);
+      if (NULL != cb)      
+        cb (cb_cls, NULL, NULL,
+	    _("Received invalid message from `PEERINFO' service."));
+      return;
     }
-#if DEBUG_PEERINFO
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-	      "Received information about peer `%s' from peerinfo database\n",
-	      GNUNET_i2s (&im->peer));
-#endif
-  nc->callback (nc->callback_cls, &im->peer, hello, ntohl (im->trust));
-  receive_notifications (nc);
+    if (0 != memcmp (&im->peer, &id, sizeof (struct GNUNET_PeerIdentity)))
+    {
+      /* malformed message */
+      GNUNET_break (0);
+      GNUNET_PEERINFO_iterate_cancel (ic);
+      reconnect (h);
+      if (NULL != cb)      
+        cb (cb_cls, NULL, NULL,
+	    _("Received invalid message from `PEERINFO' service."));
+      return;
+    }
+  }
+
+  /* normal data message */
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received %u bytes of `%s' information about peer `%s' from `%s' service\n",
+       (hello == NULL) ? 0 : (unsigned int) GNUNET_HELLO_size (hello), "HELLO",
+       GNUNET_i2s (&im->peer), "PEERINFO");
+  h->in_receive = GNUNET_YES;
+  GNUNET_CLIENT_receive (h->client, &peerinfo_handler, h,
+                         GNUNET_TIME_absolute_get_remaining (ic->timeout));
+  if (NULL != cb)
+    cb (cb_cls, &im->peer, hello, NULL);
 }
 
 
 /**
- * Read notifications from the client handle and pass them
- * to the callback.
+ * We've transmitted the iteration request.  Now get ready to process
+ * the results (or handle transmission error).
  *
- * @param nc our context
+ * @param cls the 'struct GNUNET_PEERINFO_IteratorContext'
+ * @param emsg error message, NULL if transmission worked
  */
 static void
-receive_notifications (struct GNUNET_PEERINFO_NotifyContext *nc)
+iterator_start_receive (void *cls, const char *emsg)
 {
-  GNUNET_CLIENT_receive (nc->client,
-			 &process_notification,
-			 nc,
-			 GNUNET_TIME_UNIT_FOREVER_REL);
-}
-
-
-/**
- * Transmit our init-notify request, start receiving.
- *
- * @param cls closure (our 'struct GNUNET_PEERINFO_NotifyContext')
- * @param size number of bytes available in buf
- * @param buf where the callee should write the message
- * @return number of bytes written to buf
- */
-static size_t 
-transmit_notify_request (void *cls,
-			 size_t size, 
-			 void *buf)
-{
-  struct GNUNET_PEERINFO_NotifyContext *nc = cls;
-  struct GNUNET_MessageHeader hdr;
-
-  nc->init = NULL;
-  if (buf == NULL)
-    {
-      GNUNET_CLIENT_disconnect (nc->client);
-      nc->client = GNUNET_CLIENT_connect (nc->sched, "peerinfo", nc->cfg);
-      request_notifications (nc);
-      return 0;
-    }
-  GNUNET_assert (size >= sizeof (struct GNUNET_MessageHeader));
-  hdr.size = htons (sizeof (struct GNUNET_MessageHeader));
-  hdr.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_NOTIFY);
-  memcpy (buf, &hdr, sizeof (struct GNUNET_MessageHeader));
-  receive_notifications (nc);
-  return sizeof (struct GNUNET_MessageHeader);
+  struct GNUNET_PEERINFO_IteratorContext *ic = cls;
+  struct GNUNET_PEERINFO_Handle *h = ic->h;
+  GNUNET_PEERINFO_Processor cb;
+  void *cb_cls;
+
+  ic->ac = NULL;
+  if (NULL != emsg)
+  {
+    cb = ic->callback;
+    cb_cls = ic->callback_cls;
+    GNUNET_PEERINFO_iterate_cancel (ic);
+    reconnect (h);
+    if (NULL != cb)
+      cb (cb_cls, NULL, NULL, emsg);
+    return;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "Waiting for response from `%s' service.\n",
+       "PEERINFO");
+  ic->request_transmitted = GNUNET_YES;
+  if (GNUNET_NO == h->in_receive)
+  {
+    h->in_receive = GNUNET_YES;
+    GNUNET_CLIENT_receive (h->client, &peerinfo_handler, h,
+			   GNUNET_TIME_absolute_get_remaining (ic->timeout));
+  }
 }
 
 
 /**
- * Send a request to the peerinfo service to start being
- * notified about all changes to peer information.
+ * Peerinfo iteration request has timed out.
  *
- * @param nc our context
+ * @param cls the 'struct GNUNET_PEERINFO_IteratorContext*'
+ * @param tc scheduler context
  */
 static void
-request_notifications (struct GNUNET_PEERINFO_NotifyContext *nc)
+signal_timeout (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
-  GNUNET_assert (NULL == nc->init);
-  nc->init =GNUNET_CLIENT_notify_transmit_ready (nc->client,
-						 sizeof (struct GNUNET_MessageHeader),
-						 GNUNET_TIME_UNIT_FOREVER_REL,
-						 GNUNET_YES,
-						 &transmit_notify_request,
-						 nc);
+  struct GNUNET_PEERINFO_IteratorContext *ic = cls;
+  GNUNET_PEERINFO_Processor cb;
+  void *cb_cls;
+
+  ic->timeout_task = GNUNET_SCHEDULER_NO_TASK;
+  cb = ic->callback;
+  cb_cls = ic->callback_cls;
+  GNUNET_PEERINFO_iterate_cancel (ic);
+  if (NULL != cb)
+    cb (cb_cls, NULL, NULL,
+	_("Timeout transmitting iteration request to `PEERINFO' service."));
 }
 
 
 /**
- * Call a method whenever our known information about peers
- * changes.  Initially calls the given function for all known
- * peers and then only signals changes.
+ * Call a method for each known matching host.  The callback method
+ * will be invoked once for each matching host and then finally once
+ * with a NULL pointer.  After that final invocation, the iterator
+ * context must no longer be used.
  *
- * @param cfg configuration to use
- * @param sched scheduler to use
+ * Instead of calling this function with 'peer == NULL' it is often
+ * better to use 'GNUNET_PEERINFO_notify'.
+ *
+ * @param h handle to the peerinfo service
+ * @param include_friend_only include HELLO messages for friends only
+ * @param peer restrict iteration to this peer only (can be NULL)
+ * @param timeout how long to wait until timing out
  * @param callback the method to call for each peer
  * @param callback_cls closure for callback
- * @return NULL on error
+ * @return iterator context
  */
-struct GNUNET_PEERINFO_NotifyContext *
-GNUNET_PEERINFO_notify (const struct GNUNET_CONFIGURATION_Handle *cfg,
-			struct GNUNET_SCHEDULER_Handle *sched,
-			GNUNET_PEERINFO_Processor callback,
-			void *callback_cls)
+struct GNUNET_PEERINFO_IteratorContext *
+GNUNET_PEERINFO_iterate (struct GNUNET_PEERINFO_Handle *h,
+												 int include_friend_only,
+                         const struct GNUNET_PeerIdentity *peer,
+                         struct GNUNET_TIME_Relative timeout,
+                         GNUNET_PEERINFO_Processor callback, void *callback_cls)
 {
-  struct GNUNET_PEERINFO_NotifyContext *nc;
-  struct GNUNET_CLIENT_Connection *client;
-
-  client = GNUNET_CLIENT_connect (sched, "peerinfo", cfg);
-  if (client == NULL)
-    {      
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("Could not connect to `%s' service.\n"), "peerinfo");
-      return NULL;
-    }
-  nc = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_NotifyContext));
-  nc->sched = sched;
-  nc->cfg = cfg;
-  nc->client = client;
-  nc->callback = callback;
-  nc->callback_cls = callback_cls; 
-  request_notifications (nc);
-  return nc;
+  struct ListAllPeersMessage *lapm;
+  struct ListPeerMessage *lpm;
+  struct GNUNET_PEERINFO_IteratorContext *ic;
+  struct GNUNET_PEERINFO_AddContext *ac;
+
+  ic = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_IteratorContext));
+  if (NULL == peer)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Requesting list of peers from PEERINFO service\n");
+    ac =
+        GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_AddContext) +
+                       sizeof (struct ListAllPeersMessage));
+    ac->size = sizeof (struct ListAllPeersMessage);
+    lapm = (struct ListAllPeersMessage *) &ac[1];
+    lapm->header.size = htons (sizeof (struct ListAllPeersMessage));
+    lapm->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_GET_ALL);
+    lapm->include_friend_only = htonl (include_friend_only);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Requesting information on peer `%4s' from PEERINFO service\n",
+         GNUNET_i2s (peer));
+    ac =
+        GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_AddContext) +
+                       sizeof (struct ListPeerMessage));
+    ac->size = sizeof (struct ListPeerMessage);
+    lpm = (struct ListPeerMessage *) &ac[1];
+    lpm->header.size = htons (sizeof (struct ListPeerMessage));
+    lpm->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_GET);
+    lpm->include_friend_only = htonl (include_friend_only);
+    memcpy (&lpm->peer, peer, sizeof (struct GNUNET_PeerIdentity));
+    ic->have_peer = GNUNET_YES;
+    ic->peer = *peer;
+  }
+  ic->h = h;
+  ic->ac = ac;
+  ic->callback = callback;
+  ic->callback_cls = callback_cls;
+  ic->timeout = GNUNET_TIME_relative_to_absolute (timeout);
+  ic->timeout_task =
+      GNUNET_SCHEDULER_add_delayed (timeout, &signal_timeout, ic);
+  ac->cont = &iterator_start_receive;
+  ac->cont_cls = ic;
+  GNUNET_CONTAINER_DLL_insert_tail (h->ac_head, h->ac_tail, ac);
+  GNUNET_CONTAINER_DLL_insert_tail (h->ic_head,
+				    h->ic_tail,
+				    ic);
+  trigger_transmit (h);
+  return ic;
 }
 
 
 /**
- * Stop notifying about changes.
+ * Cancel an iteration over peer information.
  *
- * @param nc context to stop notifying
+ * @param ic context of the iterator to cancel
  */
 void
-GNUNET_PEERINFO_notify_cancel (struct GNUNET_PEERINFO_NotifyContext *nc)
+GNUNET_PEERINFO_iterate_cancel (struct GNUNET_PEERINFO_IteratorContext *ic)
 {
-  if (NULL != nc->init)
-    {
-      GNUNET_CLIENT_notify_transmit_ready_cancel (nc->init);
-      nc->init = NULL;
-    }
-  GNUNET_CLIENT_disconnect (nc->client);
-  GNUNET_free (nc);
+  struct GNUNET_PEERINFO_Handle *h;
+
+  h = ic->h;
+  if (GNUNET_SCHEDULER_NO_TASK != ic->timeout_task)
+  {
+    GNUNET_SCHEDULER_cancel (ic->timeout_task);
+    ic->timeout_task = GNUNET_SCHEDULER_NO_TASK;
+  }
+  ic->callback = NULL;
+  if (GNUNET_YES == ic->request_transmitted)
+    return;                     /* need to finish processing */
+  GNUNET_CONTAINER_DLL_remove (h->ic_head,
+			       h->ic_tail,
+			       ic);
+  if (NULL != ic->ac)
+  {
+    GNUNET_CONTAINER_DLL_remove (h->ac_head, h->ac_tail, ic->ac);
+    GNUNET_free (ic->ac);
+  }
+  GNUNET_free (ic);
 }