Fixed failing test and discrepancy between documentation and implemented functionality:
[oweals/gnunet.git] / src / peerinfo / peerinfo_api.c
index 0f95a421a2e50986bcc9322a126048204d6bc4d0..a0cb5c5c4a94323aba029ffcdb1d79393d0e6006 100644 (file)
@@ -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 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
  */
 #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)
-
-
-struct CAFContext
-{
-  struct GNUNET_CLIENT_Connection *client;
-  struct GNUNET_MessageHeader *msg;
-};
+/**
+ * Function to call after transmission has succeeded.
+ * 
+ * @param cls closure
+ * @param success GNUNET_OK if transmission worked, GNUNET_SYSERR on error
+ */
+typedef void (*TransmissionContinuation)(void *cls,
+                                        int success);
 
 
-static size_t
-copy_and_free (void *cls, size_t size, void *buf)
+/**
+ * Entry in the transmission queue to PEERINFO service.
+ */
+struct TransmissionQueueEntry
 {
-  struct CAFContext *cc = cls;
-  struct GNUNET_MessageHeader *msg = cc->msg;
-  uint16_t msize;
-
-  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;
-}
+  /**
+   * This is a linked list.
+   */
+  struct TransmissionQueueEntry *next;
+  
+  /**
+   * This is a linked list.
+   */
+  struct TransmissionQueueEntry *prev;
 
+  /**
+   * Function to call after request has been transmitted, or NULL (in which
+   * case we must consider sending the next entry immediately).
+   */
+  TransmissionContinuation cont;
+  
+  /**
+   * Closure for 'cont'.
+   */
+  void *cont_cls;
 
+  /**
+   * Timeout for the operation.
+   */
+  struct GNUNET_TIME_Absolute timeout;
 
-/**
- * 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;
+  /**
+   * Number of bytes of the request message (follows after this struct).
+   */
+  size_t size;
 
-#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.
+ * Handle to the peerinfo service.
  */
-struct GNUNET_PEERINFO_IteratorContext
+struct GNUNET_PEERINFO_Handle
 {
+  /**
+   * Our configuration.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
 
   /**
-   * Our connection to the PEERINFO service.
+   * Connection to the service.
    */
   struct GNUNET_CLIENT_Connection *client;
 
   /**
-   * Function to call with information.
+   * Head of transmission queue.
    */
-  GNUNET_PEERINFO_Processor callback;
+  struct TransmissionQueueEntry *tq_head;
 
   /**
-   * Closure for callback.
+   * Tail of transmission queue.
    */
-  void *callback_cls;
+  struct TransmissionQueueEntry *tq_tail;
 
   /**
-   * When should we time out?
+   * Handle for the current transmission request, or NULL if none is pending.
    */
-  struct GNUNET_TIME_Absolute timeout;
+  struct GNUNET_CLIENT_TransmitHandle *th;
+
+  /**
+   * Set to GNUNET_YES if we are currently receiving replies from the
+   * service.
+   */
+  int in_receive;
 
 };
 
 
 /**
- * Type of a function to call when we receive a message
- * from the service.
+ * Connect to the peerinfo service.
  *
- * @param cls closure
- * @param msg message received, NULL on timeout or fatal error
+ * @param cfg configuration to use
+ * @return NULL on error (configuration related, actual connection
+ *         establishment may happen asynchronously).
  */
-static void
-info_handler (void *cls, const struct GNUNET_MessageHeader *msg)
+struct GNUNET_PEERINFO_Handle *
+GNUNET_PEERINFO_connect (const struct GNUNET_CONFIGURATION_Handle *cfg)
 {
-  struct GNUNET_PEERINFO_IteratorContext *ic = cls;
-  const struct InfoMessage *im;
-  const struct GNUNET_HELLO_Message *hello;
-  uint16_t ms;
+  struct GNUNET_CLIENT_Connection *client;
+  struct GNUNET_PEERINFO_Handle *ret;
 
-  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;
+  client = GNUNET_CLIENT_connect ("peerinfo", cfg);
+  if (client == NULL)
+    return NULL;
+  ret = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_Handle));
+  ret->client = client;
+  ret->cfg = cfg;
+  return ret;
+}
+
+
+/**
+ * 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 h handle to disconnect
+ */
+void
+GNUNET_PEERINFO_disconnect (struct GNUNET_PEERINFO_Handle *h)
+{
+  struct TransmissionQueueEntry *tqe;
+
+  while (NULL != (tqe = h->tq_head))
+    {     
+      GNUNET_CONTAINER_DLL_remove (h->tq_head,
+                                  h->tq_tail,
+                                  tqe);
+      if (tqe->cont != NULL)
+       tqe->cont (tqe->cont_cls, GNUNET_SYSERR);
+      GNUNET_free (tqe);
     }
-  im = (const struct InfoMessage *) msg;
-  hello = NULL;
-  if (ms > sizeof (struct InfoMessage) + sizeof (struct GNUNET_MessageHeader))
+  if (h->th != NULL)
     {
-      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;
-        }
+      GNUNET_CLIENT_notify_transmit_ready_cancel (h->th);
+      h->th = NULL;
     }
-#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",
-             (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));
+  GNUNET_CLIENT_disconnect (h->client, GNUNET_NO);
+  GNUNET_free (h);
 }
 
 
 /**
- * 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.
+ * Check if we have a request pending in the transmission queue and are
+ * able to transmit it right now.  If so, schedule transmission.
  *
- * @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
+ * @param h handle to the service
  */
-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)
+static void
+trigger_transmit (struct GNUNET_PEERINFO_Handle *h);
+
+
+/**
+ * Close the existing connection to PEERINFO and reconnect.
+ *
+ * @param h handle to the service
+ */
+static void
+reconnect (struct GNUNET_PEERINFO_Handle *h)
 {
-  struct GNUNET_CLIENT_Connection *client;
-  struct ListAllPeersMessage *lapm;
-  struct ListPeerMessage *lpm;
-  struct GNUNET_PEERINFO_IteratorContext *ihc;
+  GNUNET_CLIENT_disconnect (h->client, GNUNET_SYSERR);
+  h->th = NULL;
+  h->client = GNUNET_CLIENT_connect ("peerinfo", h->cfg);
+  GNUNET_assert (h->client != NULL);
+}
 
-  client = GNUNET_CLIENT_connect (sched, "peerinfo", cfg);
-  if (client == NULL)
+
+/**
+ * Transmit the request at the head of the transmission queue
+ * and trigger continuation (if any).
+ *
+ * @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 TransmissionQueueEntry *tqe = h->tq_head;
+  size_t ret;
+
+  h->th = NULL;
+  if (buf == NULL)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("Could not connect to `%s' service.\n"), "peerinfo");
-      return NULL;
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING | GNUNET_ERROR_TYPE_BULK,
+                  _("Failed to transmit message to `%s' service.\n"),
+                 "PEERINFO");
+      if (tqe != NULL)
+       GNUNET_CONTAINER_DLL_remove (h->tq_head,
+                                    h->tq_tail,
+                                    tqe);
+      reconnect (h);
+      trigger_transmit (h);
+      if (tqe != NULL)
+       {
+         if (tqe->cont != NULL)
+           tqe->cont (tqe->cont_cls, GNUNET_SYSERR);
+         GNUNET_free (tqe);
+       }
+      return 0;
     }
+  /* If it can be NULL above, it can be NULL here to... */
+  if (tqe == NULL)
+    return 0;
+
+  ret = tqe->size;
+  GNUNET_assert (size >= ret);
+  memcpy (buf, &tqe[1], ret);
 #if DEBUG_PEERINFO
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Requesting list of peers from peerinfo database\n");
+             "Transmitting request of size %u to `%s' service.\n",
+             ret, 
+             "PEERINFO");
 #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);
-    }
+   GNUNET_CONTAINER_DLL_remove (h->tq_head,
+                              h->tq_tail,
+                              tqe);
+  if (tqe->cont != NULL)
+    tqe->cont (tqe->cont_cls, GNUNET_OK);
   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,
+    trigger_transmit (h);
+  GNUNET_free (tqe);
+  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
+trigger_transmit (struct GNUNET_PEERINFO_Handle *h)
+{
+  struct TransmissionQueueEntry *tqe;
+
+  if (NULL == (tqe = h->tq_head))
+    return NULL;
+  if (h->th != NULL)
+    return NULL;
+  if (h->in_receive == GNUNET_YES)
+    return NULL;
+  h->th = GNUNET_CLIENT_notify_transmit_ready (h->client,
+                                              tqe->size,
+                                              GNUNET_TIME_absolute_get_remaining (tqe->timeout),
                                               GNUNET_YES,
-                                              &info_handler,
-                                              ihc))
-    {
-      GNUNET_break (0);
-      GNUNET_CLIENT_disconnect (ihc->client);
-      GNUNET_free (ihc);
-      return NULL;
-    }
-  return ihc;
+                                              &do_transmit, h);  
 }
 
 
 /**
- * Cancel an iteration over peer information.
+ * 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 ic context of the iterator to cancel
+ * @param h handle to the peerinfo service
+ * @param hello the verified (!) HELLO message
  */
 void
-GNUNET_PEERINFO_iterate_cancel (struct GNUNET_PEERINFO_IteratorContext *ic)
+GNUNET_PEERINFO_add_peer (struct GNUNET_PEERINFO_Handle *h,
+                         const struct GNUNET_HELLO_Message *hello)
 {
-  GNUNET_CLIENT_disconnect (ic->client);
-  GNUNET_free (ic);
+  uint16_t hs = GNUNET_HELLO_size (hello);
+  struct TransmissionQueueEntry *tqe;
+  
+#if DEBUG_PEERINFO
+  struct GNUNET_PeerIdentity peer;
+  GNUNET_assert (GNUNET_OK == GNUNET_HELLO_get_id (hello, &peer));
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Adding peer `%s' to PEERINFO database (%u bytes of `%s')\n",
+             GNUNET_i2s(&peer),
+             hs,
+             "HELLO");
+#endif
+  tqe = GNUNET_malloc (sizeof (struct TransmissionQueueEntry) + hs);
+  tqe->size = hs;
+  tqe->timeout = GNUNET_TIME_UNIT_FOREVER_ABS;
+  memcpy (&tqe[1], hello, hs);
+  GNUNET_CONTAINER_DLL_insert_after (h->tq_head,
+                                    h->tq_tail,
+                                    h->tq_tail,
+                                    tqe);
+  trigger_transmit (h);
 }
 
 
 /**
- * Context for the info handler.
+ * Context for an iteration request.
  */
-struct GNUNET_PEERINFO_NotifyContext
+struct GNUNET_PEERINFO_IteratorContext
 {
-
   /**
-   * Our connection to the PEERINFO service.
+   * Handle to the PEERINFO service.
    */
-  struct GNUNET_CLIENT_Connection *client;
+  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;
 
   /**
-   * Handle to our initial request for message transmission to
-   * the peerinfo service.
+   * Our entry in the transmission queue.
    */
-  struct GNUNET_CLIENT_TransmitHandle *init;
+  struct TransmissionQueueEntry *tqe;
 
   /**
-   * Configuration.
+   * Task responsible for timeout.
    */
-  const struct GNUNET_CONFIGURATION_Handle *cfg;
+  GNUNET_SCHEDULER_TaskIdentifier timeout_task;
 
   /**
-   * Scheduler.
+   * Timeout for the operation.
    */
-  struct GNUNET_SCHEDULER_Handle *sched;
-};
-
-
-/**
- * Send a request to the peerinfo service to start being
- * notified about all changes to peer information.
- *
- * @param nc our context
- */
-static void
-request_notifications (struct GNUNET_PEERINFO_NotifyContext *nc);
-
+  struct GNUNET_TIME_Absolute timeout;
 
-/**
- * Read notifications from the client handle and pass them
- * to the callback.
- *
- * @param nc our context
- */
-static void
-receive_notifications (struct GNUNET_PEERINFO_NotifyContext *nc);
+  /**
+   * Are we now receiving?
+   */
+  int in_receive;
+};
 
 
 /**
- * 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.
  *
  * @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_IteratorContext *ic = cls;
   const struct InfoMessage *im;
   const struct GNUNET_HELLO_Message *hello;
   uint16_t ms;
 
+  ic->h->in_receive = GNUNET_NO;
   if (msg == NULL)
     {
-      GNUNET_CLIENT_disconnect (nc->client);
-      nc->client = GNUNET_CLIENT_connect (nc->sched, "peerinfo", nc->cfg);
-      request_notifications (nc);
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  _("Failed to receive response from `%s' service.\n"),
+                  "PEERINFO");
+      reconnect (ic->h);
+      trigger_transmit (ic->h);
+      if (ic->timeout_task != GNUNET_SCHEDULER_NO_TASK)
+       GNUNET_SCHEDULER_cancel (ic->timeout_task);
+      if (ic->callback != NULL)
+       ic->callback (ic->callback_cls, NULL, NULL);
+      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 `%s' service\n",
+                 "PEERINFO");
+#endif
+      trigger_transmit (ic->h);
+      if (ic->timeout_task != GNUNET_SCHEDULER_NO_TASK)
+       GNUNET_SCHEDULER_cancel (ic->timeout_task);
+      if (ic->callback != NULL)
+       ic->callback (ic->callback_cls, NULL, NULL);
+      GNUNET_free (ic);
       return;
     }
   ms = ntohs (msg->size);
@@ -416,156 +417,226 @@ process_notification (void *cls,
       (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_PEERINFO_INFO))
     {
       GNUNET_break (0);
-      GNUNET_CLIENT_disconnect (nc->client);
-      nc->client = GNUNET_CLIENT_connect (nc->sched, "peerinfo", nc->cfg);
-      request_notifications (nc);
+      reconnect (ic->h);
+      trigger_transmit (ic->h);
+      if (ic->timeout_task != GNUNET_SCHEDULER_NO_TASK)
+       GNUNET_SCHEDULER_cancel (ic->timeout_task);
+      if (ic->callback != NULL)
+       ic->callback (ic->callback_cls, NULL, NULL);
+      GNUNET_free (ic);
       return;
     }
   im = (const struct InfoMessage *) msg;
+  GNUNET_break (0 == ntohl (im->reserved));
   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);
-         GNUNET_CLIENT_disconnect (nc->client);
-         nc->client = GNUNET_CLIENT_connect (nc->sched, "peerinfo", nc->cfg);
-         request_notifications (nc);
+         GNUNET_break (0);
+         reconnect (ic->h);
+         trigger_transmit (ic->h);
+         if (ic->timeout_task != GNUNET_SCHEDULER_NO_TASK)
+           GNUNET_SCHEDULER_cancel (ic->timeout_task);
+         if (ic->callback != NULL)
+           ic->callback (ic->callback_cls, NULL, NULL);
+         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));
+             "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");
 #endif
-  nc->callback (nc->callback_cls, &im->peer, hello, ntohl (im->trust));
-  receive_notifications (nc);
+  ic->h->in_receive = GNUNET_YES;
+  if (ic->callback != NULL)
+    ic->callback (ic->callback_cls, &im->peer, hello);
+  GNUNET_CLIENT_receive (ic->h->client,
+                         &peerinfo_handler,
+                         ic,
+                         GNUNET_TIME_absolute_get_remaining (ic->timeout));
 }
 
 
 /**
- * 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 transmit_success GNUNET_OK if transmission worked
  */
 static void
-receive_notifications (struct GNUNET_PEERINFO_NotifyContext *nc)
+iterator_start_receive (void *cls,
+                       int transmit_success)
 {
-  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;
+  struct GNUNET_PEERINFO_IteratorContext *ic = cls;
 
-  nc->init = NULL;
-  if (buf == NULL)
+  if (GNUNET_OK != transmit_success)
     {
-      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);
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("Failed to transmit iteration request to `%s' service (%d).\n"),
+                 "PEERINFO",
+                 transmit_success);
+      if (ic->timeout_task != GNUNET_SCHEDULER_NO_TASK)
+       {
+         GNUNET_SCHEDULER_cancel (ic->timeout_task);
+         ic->timeout_task = GNUNET_SCHEDULER_NO_TASK;
+       }
+      reconnect (ic->h);
+      trigger_transmit (ic->h);
+      if (ic->callback != NULL)
+       ic->callback (ic->callback_cls, NULL, NULL);
+      GNUNET_free (ic);
+      return;
+    }  
+#if DEBUG_PEERINFO
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Waiting for response from `%s' service.\n",
+             "PEERINFO");
+#endif
+  ic->h->in_receive = GNUNET_YES;
+  ic->in_receive = GNUNET_YES;
+  ic->tqe = NULL;
+  GNUNET_CLIENT_receive (ic->h->client,
+                         &peerinfo_handler,
+                         ic,
+                         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_log (GNUNET_ERROR_TYPE_WARNING | GNUNET_ERROR_TYPE_BULK,
+             _("Timeout transmitting iteration request to `%s' service.\n"),
+             "PEERINFO");
+  ic->timeout_task = GNUNET_SCHEDULER_NO_TASK;
+  if (! ic->in_receive)
+    GNUNET_CONTAINER_DLL_remove (ic->h->tq_head,
+                                ic->h->tq_tail,
+                                ic->tqe);
+  reconnect (ic->h);
+  ic->callback (ic->callback_cls, NULL, NULL);
+  ic->callback = NULL;
+  GNUNET_free_non_null (ic->tqe);
+  GNUNET_free (ic);
 }
 
 
 /**
- * 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 and change its trust
+ * value.  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 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,
+                        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;
+  struct GNUNET_MessageHeader *lapm;
+  struct ListPeerMessage *lpm;
+  struct GNUNET_PEERINFO_IteratorContext *ic;
+  struct TransmissionQueueEntry *tqe;
 
-  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 (peer == NULL)
+    {
+#if DEBUG_PEERINFO
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                 "Requesting list of peers from PEERINFO service\n");
+#endif
+      tqe = GNUNET_malloc (sizeof (struct TransmissionQueueEntry) +
+                          sizeof (struct GNUNET_MessageHeader));
+      tqe->size = sizeof (struct GNUNET_MessageHeader);
+      lapm = (struct GNUNET_MessageHeader *) &tqe[1];
+      lapm->size = htons (sizeof (struct GNUNET_MessageHeader));
+      lapm->type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_GET_ALL);
+    }
+  else
+    {
+#if DEBUG_PEERINFO
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                 "Requesting information on peer `%4s' from PEERINFO service\n",
+                 GNUNET_i2s (peer));
+#endif
+      tqe = GNUNET_malloc (sizeof (struct TransmissionQueueEntry) +
+                          sizeof (struct ListPeerMessage));
+      tqe->size = sizeof (struct ListPeerMessage);
+      lpm = (struct ListPeerMessage *) &tqe[1];
+      lpm->header.size = htons (sizeof (struct ListPeerMessage));
+      lpm->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_GET);
+      memcpy (&lpm->peer, peer, sizeof (struct GNUNET_PeerIdentity));
     }
-  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;
+  ic = GNUNET_malloc (sizeof (struct GNUNET_PEERINFO_IteratorContext));
+  ic->h = h;
+  ic->tqe = tqe;
+  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);
+  tqe->timeout = ic->timeout;
+  tqe->cont = &iterator_start_receive;
+  tqe->cont_cls = ic;
+  tqe->timeout = ic->timeout;
+  GNUNET_CONTAINER_DLL_insert_after (h->tq_head,
+                                    h->tq_tail,
+                                    h->tq_tail,
+                                    tqe);
+  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)
+  if (ic->timeout_task != GNUNET_SCHEDULER_NO_TASK)
     {
-      GNUNET_CLIENT_notify_transmit_ready_cancel (nc->init);
-      nc->init = NULL;
+      GNUNET_SCHEDULER_cancel (ic->timeout_task);
+      ic->timeout_task = GNUNET_SCHEDULER_NO_TASK;
     }
-  GNUNET_CLIENT_disconnect (nc->client);
-  GNUNET_free (nc);
+  ic->callback = NULL;
+  if (ic->in_receive)
+    return; /* need to finish processing */
+  GNUNET_CONTAINER_DLL_remove (ic->h->tq_head,
+                              ic->h->tq_tail,
+                              ic->tqe);
+  GNUNET_free (ic->tqe);
+  GNUNET_free (ic);
 }