changing time measurement from milliseconds to microseconds
[oweals/gnunet.git] / src / util / client.c
index 8349a14f4ca4b7e6f39560fbe676ebcb9015cffd..6c5e93ce4444acc9388322a6d147b9ddda01fb1f 100644 (file)
@@ -1,10 +1,10 @@
 /*
      This file is part of GNUnet.
-     (C) 2001, 2002, 2006, 2008, 2009 Christian Grothoff (and other contributing authors)
+     (C) 2001-2013 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
  * Generic TCP code for reliable, record-oriented TCP
  * connections between clients and service providers.
  */
-
 #include "platform.h"
-#include "gnunet_common.h"
-#include "gnunet_client_lib.h"
 #include "gnunet_protocols.h"
-#include "gnunet_server_lib.h"
-#include "gnunet_scheduler_lib.h"
-
-#define DEBUG_CLIENT GNUNET_NO
+#include "gnunet_util_lib.h"
 
 
 /**
@@ -42,8 +36,9 @@
  * Note that if we succeeded transmitting a request but failed to read
  * a response, we do NOT re-try.
  */
-#define MAX_ATTEMPTS 10
+#define MAX_ATTEMPTS 50
 
+#define LOG(kind,...) GNUNET_log_from (kind, "util",__VA_ARGS__)
 
 /**
  * Handle for a transmission request.
@@ -53,7 +48,7 @@ struct GNUNET_CLIENT_TransmitHandle
   /**
    * Connection state.
    */
-  struct GNUNET_CLIENT_Connection *sock;
+  struct GNUNET_CLIENT_Connection *client;
 
   /**
    * Function to call to get the data for transmission.
@@ -78,7 +73,7 @@ struct GNUNET_CLIENT_TransmitHandle
   GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
 
   /**
-   * Timeout.
+   * Timeout for the operation overall.
    */
   struct GNUNET_TIME_Absolute timeout;
 
@@ -105,7 +100,7 @@ struct GNUNET_CLIENT_TransmitHandle
 
 
 /**
- * Context for processing 
+ * Context for processing
  * "GNUNET_CLIENT_transmit_and_get_response" requests.
  */
 struct TransmitGetResponseContext
@@ -113,7 +108,7 @@ struct TransmitGetResponseContext
   /**
    * Client handle.
    */
-  struct GNUNET_CLIENT_Connection *sock;
+  struct GNUNET_CLIENT_Connection *client;
 
   /**
    * Message to transmit; do not free, allocated
@@ -137,7 +132,6 @@ struct TransmitGetResponseContext
   void *rn_cls;
 };
 
-
 /**
  * Struct to refer to a GNUnet TCP connection.
  * This is more than just a socket because if the server
@@ -148,19 +142,14 @@ struct GNUNET_CLIENT_Connection
 {
 
   /**
-   * the socket handle, NULL if not live
+   * The connection handle, NULL if not live
    */
-  struct GNUNET_CONNECTION_Handle *sock;
-
-  /**
-   * Our scheduler.
-   */
-  struct GNUNET_SCHEDULER_Handle *sched;
+  struct GNUNET_CONNECTION_Handle *connection;
 
   /**
    * Our configuration.
    */
-  struct GNUNET_CONFIGURATION_Handle *cfg;
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
 
   /**
    * Name of the service we interact with.
@@ -189,22 +178,12 @@ struct GNUNET_CLIENT_Connection
    */
   struct GNUNET_CLIENT_TransmitHandle *th;
 
-  /**
-   * Handler for service test completion (NULL unless in service_test)
-   */
-  GNUNET_SCHEDULER_Task test_cb;
-
   /**
    * If we are re-trying and are delaying to do so,
    * handle to the scheduled task managing the delay.
    */
   GNUNET_SCHEDULER_TaskIdentifier receive_task;
 
-  /**
-   * Closure for test_cb (NULL unless in service_test)
-   */
-  void *test_cb_cls;
-
   /**
    * Buffer for received message.
    */
@@ -215,6 +194,12 @@ struct GNUNET_CLIENT_Connection
    */
   struct GNUNET_TIME_Absolute receive_timeout;
 
+  /**
+   * Current value for our incremental back-off (for
+   * connect re-tries).
+   */
+  struct GNUNET_TIME_Relative back_off;
+
   /**
    * Number of bytes in received_buf that are valid.
    */
@@ -236,78 +221,202 @@ struct GNUNET_CLIENT_Connection
    */
   int in_receive;
 
+  /**
+   * Is this the first message we are sending to the service?
+   */
+  int first_message;
+
+  /**
+   * How often have we tried to connect?
+   */
+  unsigned int attempts;
+
 };
 
 
+/**
+ * Try connecting to the server using UNIX domain sockets.
+ *
+ * @param service_name name of service to connect to
+ * @param cfg configuration to use
+ * @return NULL on error, connection to UNIX otherwise
+ */
+static struct GNUNET_CONNECTION_Handle *
+try_unixpath (const char *service_name,
+             const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+#if AF_UNIX
+  struct GNUNET_CONNECTION_Handle *connection;
+  char *unixpath;
+  struct sockaddr_un s_un;
+
+  unixpath = NULL;
+  if ((GNUNET_OK == GNUNET_CONFIGURATION_get_value_string (cfg, service_name, "UNIXPATH", &unixpath)) && 
+      (0 < strlen (unixpath)))     
+  {
+    /* We have a non-NULL unixpath, need to validate it */
+    if (strlen (unixpath) >= sizeof (s_un.sun_path))
+    {
+      LOG (GNUNET_ERROR_TYPE_WARNING,
+          _("UNIXPATH `%s' too long, maximum length is %llu\n"), unixpath,
+          (unsigned long long) sizeof (s_un.sun_path));
+      unixpath = GNUNET_NETWORK_shorten_unixpath (unixpath);
+      LOG (GNUNET_ERROR_TYPE_INFO,
+          _("Using `%s' instead\n"), unixpath);
+    }
+    connection = GNUNET_CONNECTION_create_from_connect_to_unixpath (cfg, unixpath);
+    if (NULL != connection)
+    {
+      LOG (GNUNET_ERROR_TYPE_DEBUG, "Connected to unixpath `%s'!\n",
+          unixpath);
+      GNUNET_free (unixpath);
+      return connection;
+    }
+  }
+  GNUNET_free_non_null (unixpath);
+#endif
+  return NULL;
+}
+
+
+/**
+ * Test whether the configuration has proper values for connection
+ * (UNIXPATH || (PORT && HOSTNAME)).
+ *
+ * @param service_name name of service to connect to
+ * @param cfg configuration to use
+ * @return GNUNET_OK if the configuration is valid, GNUNET_SYSERR if not
+ */
+static int
+test_service_configuration (const char *service_name,
+                           const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  int ret = GNUNET_SYSERR;
+  char *hostname = NULL;
+  unsigned long long port;
+#if AF_UNIX
+  char *unixpath = NULL;
+
+  if ((GNUNET_OK == GNUNET_CONFIGURATION_get_value_string (cfg, service_name, "UNIXPATH", &unixpath)) && 
+      (0 < strlen (unixpath)))     
+    ret = GNUNET_OK;
+  GNUNET_free_non_null (unixpath);
+#endif
+
+  if ( (GNUNET_YES ==
+       GNUNET_CONFIGURATION_have_value (cfg, service_name, "PORT")) &&
+       (GNUNET_OK ==
+       GNUNET_CONFIGURATION_get_value_number (cfg, service_name, "PORT", &port)) && 
+       (port <= 65535) && (0 != port) &&
+       (GNUNET_OK ==
+       GNUNET_CONFIGURATION_get_value_string (cfg, service_name, "HOSTNAME",
+                                              &hostname)) &&
+       (0 != strlen (hostname)) )
+    ret = GNUNET_OK;
+  GNUNET_free_non_null (hostname);
+  return ret;
+}
+
+
+/**
+ * Try to connect to the service.
+ *
+ * @param service_name name of service to connect to
+ * @param cfg configuration to use
+ * @param attempt counter used to alternate between IP and UNIX domain sockets
+ * @return NULL on error
+ */
 static struct GNUNET_CONNECTION_Handle *
-do_connect (struct GNUNET_SCHEDULER_Handle *sched,
-            const char *service_name,
-            const struct GNUNET_CONFIGURATION_Handle *cfg)
+do_connect (const char *service_name,
+            const struct GNUNET_CONFIGURATION_Handle *cfg, unsigned int attempt)
 {
-  struct GNUNET_CONNECTION_Handle *sock;
+  struct GNUNET_CONNECTION_Handle *connection;
   char *hostname;
   unsigned long long port;
 
-  if ((GNUNET_OK !=
-       GNUNET_CONFIGURATION_get_value_number (cfg,
-                                              service_name,
-                                              "PORT",
-                                              &port)) ||
-      (port > 65535) ||
-      (GNUNET_OK !=
-       GNUNET_CONFIGURATION_get_value_string (cfg,
-                                              service_name,
-                                              "HOSTNAME", &hostname)))
+  connection = NULL;
+  if (0 == (attempt % 2))
+  {
+    /* on even rounds, try UNIX first */
+    connection = try_unixpath (service_name, cfg);
+    if (NULL != connection)
+      return connection;
+  }
+  if (GNUNET_YES ==
+      GNUNET_CONFIGURATION_have_value (cfg, service_name, "PORT"))
+  {
+    if ((GNUNET_OK !=
+        GNUNET_CONFIGURATION_get_value_number (cfg, service_name, "PORT", &port))
+       || (port > 65535) ||
+       (GNUNET_OK !=
+        GNUNET_CONFIGURATION_get_value_string (cfg, service_name, "HOSTNAME",
+                                               &hostname)))
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _
-                  ("Could not determine valid hostname and port for service `%s' from configuration.\n"),
-                  service_name);
+      LOG (GNUNET_ERROR_TYPE_WARNING,
+          _
+          ("Could not determine valid hostname and port for service `%s' from configuration.\n"),
+          service_name);
       return NULL;
     }
-  if (0 == strlen (hostname))
+    if (0 == strlen (hostname))
     {
       GNUNET_free (hostname);
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("Need a non-empty hostname for service `%s'.\n"),
-                  service_name);
+      LOG (GNUNET_ERROR_TYPE_WARNING,
+          _("Need a non-empty hostname for service `%s'.\n"), service_name);
       return NULL;
     }
-  sock = GNUNET_CONNECTION_create_from_connect (sched,
-                                                cfg,
-                                                hostname,
-                                                port,
-                                                GNUNET_SERVER_MAX_MESSAGE_SIZE);
+  }
+  else
+  {
+    /* unspecified means 0 (disabled) */
+    port = 0;
+    hostname = NULL;
+  }
+  if (0 == port)
+  {
+    /* if port is 0, try UNIX */
+    connection = try_unixpath (service_name, cfg);
+    if (NULL != connection)
+      return connection;
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Port is 0 for service `%s', UNIXPATH did not work, returning NULL!\n",
+         service_name);
+    GNUNET_free_non_null (hostname);
+    return NULL;
+  }
+  connection = GNUNET_CONNECTION_create_from_connect (cfg, hostname, port);
   GNUNET_free (hostname);
-  return sock;
+  return connection;
 }
 
 
 /**
  * Get a connection with a service.
  *
- * @param sched scheduler to use
  * @param service_name name of the service
  * @param cfg configuration to use
  * @return NULL on error (service unknown to configuration)
  */
 struct GNUNET_CLIENT_Connection *
-GNUNET_CLIENT_connect (struct GNUNET_SCHEDULER_Handle *sched,
-                       const char *service_name,
+GNUNET_CLIENT_connect (const char *service_name,
                        const struct GNUNET_CONFIGURATION_Handle *cfg)
 {
-  struct GNUNET_CLIENT_Connection *ret;
-  struct GNUNET_CONNECTION_Handle *sock;
+  struct GNUNET_CLIENT_Connection *client;
+  struct GNUNET_CONNECTION_Handle *connection;
 
-  sock = do_connect (sched, service_name, cfg);
-  if (sock == NULL)
+  if (GNUNET_OK != 
+      test_service_configuration (service_name,
+                                 cfg))
     return NULL;
-  ret = GNUNET_malloc (sizeof (struct GNUNET_CLIENT_Connection));
-  ret->sock = sock;
-  ret->sched = sched;
-  ret->service_name = GNUNET_strdup (service_name);
-  ret->cfg = GNUNET_CONFIGURATION_dup (cfg);
-  return ret;
+  connection = do_connect (service_name, cfg, 0);
+  client = GNUNET_new (struct GNUNET_CLIENT_Connection);
+  client->first_message = GNUNET_YES;
+  client->attempts = 1;
+  client->connection = connection;
+  client->service_name = GNUNET_strdup (service_name);
+  client->cfg = cfg;
+  client->back_off = GNUNET_TIME_UNIT_MILLISECONDS;
+  return client;
 }
 
 
@@ -317,55 +426,62 @@ GNUNET_CLIENT_connect (struct GNUNET_SCHEDULER_Handle *sched,
  * *NOT* be called, not even with a NULL message).  Any pending
  * transmission request will also be cancelled UNLESS the callback for
  * the transmission request has already been called, in which case the
- * transmission is guaranteed to complete before the socket is fully
- * destroyed (unless, of course, there is an error with the server
- * in which case the message may still be lost).
+ * transmission 'finish_pending_write' argument determines whether or
+ * not the write is guaranteed to complete before the socket is fully
+ * destroyed (unless, of course, there is an error with the server in
+ * which case the message may still be lost).
  *
- * @param sock handle to the service connection
+ * @param client handle to the service connection
  */
 void
-GNUNET_CLIENT_disconnect (struct GNUNET_CLIENT_Connection *sock)
+GNUNET_CLIENT_disconnect (struct GNUNET_CLIENT_Connection *client)
 {
-  GNUNET_assert (sock->sock != NULL);
-  if (sock->in_receive == GNUNET_YES)
-    {
-      GNUNET_CONNECTION_receive_cancel (sock->sock);
-      sock->in_receive = GNUNET_NO;
-    }
-  GNUNET_CONNECTION_destroy (sock->sock);
-  sock->sock = NULL;
-  if (sock->tag != NULL)
-    {
-      GNUNET_free (sock->tag);
-      sock->tag = NULL;
-    }
-  sock->receiver_handler = NULL;
-  if (sock->th != NULL)
-    GNUNET_CLIENT_notify_transmit_ready_cancel (sock->th);
-  if (sock->receive_task != GNUNET_SCHEDULER_NO_TASK)
-    {
-      GNUNET_SCHEDULER_cancel (sock->sched,
-                              sock->receive_task);
-      sock->receive_task = GNUNET_SCHEDULER_NO_TASK;
-    }
-  GNUNET_array_grow (sock->received_buf, sock->received_size, 0);
-  GNUNET_free (sock->service_name);
-  GNUNET_CONFIGURATION_destroy (sock->cfg);
-  GNUNET_free (sock);
+  if (GNUNET_YES == client->in_receive)
+  {
+    GNUNET_CONNECTION_receive_cancel (client->connection);
+    client->in_receive = GNUNET_NO;
+  }
+  if (NULL != client->th)
+  {
+    GNUNET_CLIENT_notify_transmit_ready_cancel (client->th);
+    client->th = NULL;
+  }
+  if (NULL != client->connection)
+  {
+    GNUNET_CONNECTION_destroy (client->connection);
+    client->connection = NULL;
+  }
+  if (GNUNET_SCHEDULER_NO_TASK != client->receive_task)
+  {
+    GNUNET_SCHEDULER_cancel (client->receive_task);
+    client->receive_task = GNUNET_SCHEDULER_NO_TASK;
+  }
+  if (NULL != client->tag)
+  {
+    GNUNET_free (client->tag);
+    client->tag = NULL;
+  }
+  client->receiver_handler = NULL;
+  GNUNET_array_grow (client->received_buf, client->received_size, 0);
+  GNUNET_free (client->service_name);
+  GNUNET_free (client);
 }
 
 
 /**
- * Check if message is complete
+ * Check if message is complete.  Sets the "msg_complete" member
+ * in the client struct.
+ *
+ * @param client connection with the buffer to check
  */
 static void
-check_complete (struct GNUNET_CLIENT_Connection *conn)
+check_complete (struct GNUNET_CLIENT_Connection *client)
 {
-  if ((conn->received_pos >= sizeof (struct GNUNET_MessageHeader)) &&
-      (conn->received_pos >=
-       ntohs (((const struct GNUNET_MessageHeader *) conn->received_buf)->
+  if ((client->received_pos >= sizeof (struct GNUNET_MessageHeader)) &&
+      (client->received_pos >=
+       ntohs (((const struct GNUNET_MessageHeader *) client->received_buf)->
               size)))
-    conn->msg_complete = GNUNET_YES;
+    client->msg_complete = GNUNET_YES;
 }
 
 
@@ -382,53 +498,54 @@ check_complete (struct GNUNET_CLIENT_Connection *conn)
  * @param errCode value of errno (on errors receiving)
  */
 static void
-receive_helper (void *cls,
-                const void *buf,
-                size_t available,
+receive_helper (void *cls, const void *buf, size_t available,
                 const struct sockaddr *addr, socklen_t addrlen, int errCode)
 {
-  struct GNUNET_CLIENT_Connection *conn = cls;
+  struct GNUNET_CLIENT_Connection *client = cls;
   struct GNUNET_TIME_Relative remaining;
-  GNUNET_CLIENT_MessageHandler receiver_handler;
+  GNUNET_CLIENT_MessageHandler receive_handler;
   void *receive_handler_cls;
 
-  GNUNET_assert (conn->msg_complete == GNUNET_NO);
-  conn->in_receive = GNUNET_NO;
-  if ((available == 0) || (conn->sock == NULL) || (errCode != 0))
+  GNUNET_assert (GNUNET_NO == client->msg_complete);
+  GNUNET_assert (GNUNET_YES == client->in_receive);
+  client->in_receive = GNUNET_NO;
+  if ((0 == available) || (NULL == client->connection) || (0 != errCode))
+  {
+    /* signal timeout! */
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Timeout in receive_helper, available %u, client->connection %s, errCode `%s'\n",
+         (unsigned int) available, NULL == client->connection ? "NULL" : "non-NULL",
+         STRERROR (errCode));
+    if (NULL != (receive_handler = client->receiver_handler))
     {
-      /* signal timeout! */
-      if (NULL != (receive_handler = conn->receiver_handler))
-        {
-         receive_handler_cls = conn->receiver_handler_cls;
-          conn->receiver_handler = NULL;
-          receiver_handler (receive_handler_cls, NULL);
-        }
-      return;
+      receive_handler_cls = client->receiver_handler_cls;
+      client->receiver_handler = NULL;
+      receive_handler (receive_handler_cls, NULL);
     }
-
+    return;
+  }
   /* FIXME: optimize for common fast case where buf contains the
-     entire message and we need no copying... */
-
+   * entire message and we need no copying... */
 
   /* slow path: append to array */
-  if (conn->received_size < conn->received_pos + available)
-    GNUNET_array_grow (conn->received_buf,
-                       conn->received_size, conn->received_pos + available);
-  memcpy (&conn->received_buf[conn->received_pos], buf, available);
-  conn->received_pos += available;
-  check_complete (conn);
+  if (client->received_size < client->received_pos + available)
+    GNUNET_array_grow (client->received_buf, client->received_size,
+                       client->received_pos + available);
+  memcpy (&client->received_buf[client->received_pos], buf, available);
+  client->received_pos += available;
+  check_complete (client);
   /* check for timeout */
-  remaining = GNUNET_TIME_absolute_get_remaining (conn->receive_timeout);
-  if (remaining.value == 0)
-    {
-      /* signal timeout! */
-      conn->receiver_handler (conn->receiver_handler_cls, NULL);
-      return;
-    }
+  remaining = GNUNET_TIME_absolute_get_remaining (client->receive_timeout);
+  if (0 == remaining.rel_value_us)
+  {
+    /* signal timeout! */
+    if (NULL != client->receiver_handler)
+      client->receiver_handler (client->receiver_handler_cls, NULL);
+    return;
+  }
   /* back to receive -- either for more data or to call callback! */
-  GNUNET_CLIENT_receive (conn,
-                         conn->receiver_handler,
-                         conn->receiver_handler_cls, remaining);
+  GNUNET_CLIENT_receive (client, client->receiver_handler,
+                         client->receiver_handler_cls, remaining);
 }
 
 
@@ -441,26 +558,28 @@ receive_helper (void *cls,
 static void
 receive_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
-  struct GNUNET_CLIENT_Connection *sock = cls;
-  GNUNET_CLIENT_MessageHandler handler = sock->receiver_handler;
+  struct GNUNET_CLIENT_Connection *client = cls;
+  GNUNET_CLIENT_MessageHandler handler = client->receiver_handler;
   const struct GNUNET_MessageHeader *cmsg =
-    (const struct GNUNET_MessageHeader *) sock->received_buf;
-  void *handler_cls = sock->receiver_handler_cls;
+      (const struct GNUNET_MessageHeader *) client->received_buf;
+  void *handler_cls = client->receiver_handler_cls;
   uint16_t msize = ntohs (cmsg->size);
   char mbuf[msize];
   struct GNUNET_MessageHeader *msg = (struct GNUNET_MessageHeader *) mbuf;
 
-  sock->receive_task = GNUNET_SCHEDULER_NO_TASK;
-  GNUNET_assert (GNUNET_YES == sock->msg_complete);
-  GNUNET_assert (sock->received_pos >= msize);
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "Received message of type %u and size %u\n",
+       ntohs (cmsg->type), msize);
+  client->receive_task = GNUNET_SCHEDULER_NO_TASK;
+  GNUNET_assert (GNUNET_YES == client->msg_complete);
+  GNUNET_assert (client->received_pos >= msize);
   memcpy (msg, cmsg, msize);
-  memmove (sock->received_buf,
-           &sock->received_buf[msize], sock->received_pos - msize);
-  sock->received_pos -= msize;
-  sock->msg_complete = GNUNET_NO;
-  sock->receiver_handler = NULL;
-  check_complete (sock);
-  if (handler != NULL)
+  memmove (client->received_buf, &client->received_buf[msize],
+           client->received_pos - msize);
+  client->received_pos -= msize;
+  client->msg_complete = GNUNET_NO;
+  client->receiver_handler = NULL;
+  check_complete (client);
+  if (NULL != handler)
     handler (handler_cls, msg);
 }
 
@@ -468,210 +587,414 @@ receive_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 /**
  * Read from the service.
  *
- * @param sock the service
+ * @param client the service
  * @param handler function to call with the message
  * @param handler_cls closure for handler
  * @param timeout how long to wait until timing out
  */
 void
-GNUNET_CLIENT_receive (struct GNUNET_CLIENT_Connection *sock,
-                       GNUNET_CLIENT_MessageHandler handler,
-                       void *handler_cls, struct GNUNET_TIME_Relative timeout)
+GNUNET_CLIENT_receive (struct GNUNET_CLIENT_Connection *client,
+                       GNUNET_CLIENT_MessageHandler handler, void *handler_cls,
+                       struct GNUNET_TIME_Relative timeout)
 {
-  if (sock->sock == NULL)
-    {
-      /* already disconnected, fail instantly! */
-      GNUNET_break (0);         /* this should not happen in well-written code! */
+  if (NULL == client->connection)
+  {
+    /* already disconnected, fail instantly! */
+    GNUNET_break (0);           /* this should not happen in well-written code! */
+    if (NULL != handler)
       handler (handler_cls, NULL);
-      return;
-    }
-  sock->receiver_handler = handler;
-  sock->receiver_handler_cls = handler_cls;
-  sock->receive_timeout = GNUNET_TIME_relative_to_absolute (timeout);
-  if (GNUNET_YES == sock->msg_complete)
-    {
-      sock->receive_task = GNUNET_SCHEDULER_add_after (sock->sched,
-                                                      GNUNET_SCHEDULER_NO_TASK,
-                                                      &receive_task, sock);
-    }
+    return;
+  }
+  client->receiver_handler = handler;
+  client->receiver_handler_cls = handler_cls;
+  client->receive_timeout = GNUNET_TIME_relative_to_absolute (timeout);
+  if (GNUNET_YES == client->msg_complete)
+  {
+    GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == client->receive_task);
+    client->receive_task = GNUNET_SCHEDULER_add_now (&receive_task, client);
+  }
   else
-    {
-      sock->in_receive = GNUNET_YES;
-      GNUNET_CONNECTION_receive (sock->sock,
-                                GNUNET_SERVER_MAX_MESSAGE_SIZE,
-                                timeout, &receive_helper, sock);
-    }
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG, "calling GNUNET_CONNECTION_receive\n");
+    GNUNET_assert (GNUNET_NO == client->in_receive);
+    client->in_receive = GNUNET_YES;
+    GNUNET_CONNECTION_receive (client->connection, GNUNET_SERVER_MAX_MESSAGE_SIZE - 1,
+                               timeout, &receive_helper, client);
+  }
 }
 
 
 /**
- * If possible, write a shutdown message to the target
- * buffer and destroy the client connection.
- *
- * @param cls the "struct GNUNET_CLIENT_Connection" to destroy
- * @param size number of bytes available in buf
- * @param buf NULL on error, otherwise target buffer
- * @return number of bytes written to buf
+ * Handle for a test to check if a service is running.
  */
-static size_t
-write_shutdown (void *cls, size_t size, void *buf)
+struct GNUNET_CLIENT_TestHandle 
 {
-  struct GNUNET_MessageHeader *msg;
-  struct GNUNET_CLIENT_Connection *sock = cls;
+  /**
+   * Function to call with the result of the test.
+   */
+  GNUNET_CLIENT_TestResultCallback cb;
 
-  GNUNET_CLIENT_disconnect (sock);
-  if (size < sizeof (struct GNUNET_MessageHeader))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                  _("Failed to transmit shutdown request to client.\n"));
-      return 0;                 /* client disconnected */
-    }
-  msg = (struct GNUNET_MessageHeader *) buf;
-  msg->type = htons (GNUNET_MESSAGE_TYPE_SHUTDOWN);
-  msg->size = htons (sizeof (struct GNUNET_MessageHeader));
-  return sizeof (struct GNUNET_MessageHeader);
-}
+  /**
+   * Closure for 'cb'.
+   */
+  void *cb_cls;
+
+  /**
+   * Client connection we are using for the test, if any.
+   */ 
+  struct GNUNET_CLIENT_Connection *client;
+
+  /**
+   * Handle for the transmission request, if any.
+   */
+  struct GNUNET_CLIENT_TransmitHandle *th;
+
+  /**
+   * Deadline for calling 'cb'.
+   */
+  struct GNUNET_TIME_Absolute test_deadline;
+
+  /**
+   * ID of task used for asynchronous operations.
+   */
+  GNUNET_SCHEDULER_TaskIdentifier task;
+
+  /**
+   * Final result to report back (once known).
+   */
+  int result;
+};
 
 
 /**
- * Request that the service should shutdown.
- * Afterwards, the connection should be disconnected.
+ * Abort testing for service.
  *
- * @param sock the socket connected to the service
+ * @param th test handle
  */
 void
-GNUNET_CLIENT_service_shutdown (struct GNUNET_CLIENT_Connection *sock)
+GNUNET_CLIENT_service_test_cancel (struct GNUNET_CLIENT_TestHandle *th)
 {
-  GNUNET_CONNECTION_notify_transmit_ready (sock->sock,
-                                           sizeof (struct
-                                                   GNUNET_MessageHeader),
-                                           GNUNET_TIME_UNIT_FOREVER_REL,
-                                           &write_shutdown, sock);
+  if (NULL != th->th)
+  {
+    GNUNET_CLIENT_notify_transmit_ready_cancel (th->th);
+    th->th = NULL;
+  }
+  if (NULL != th->client)
+  {
+    GNUNET_CLIENT_disconnect (th->client);
+    th->client = NULL;
+  }
+  if (GNUNET_SCHEDULER_NO_TASK != th->task)
+  {
+    GNUNET_SCHEDULER_cancel (th->task);
+    th->task = GNUNET_SCHEDULER_NO_TASK;
+  }
+  GNUNET_free (th);
 }
 
 
 /**
- * Report service unavailable.
+ * Task that reports back the result by calling the callback
+ * and then cleans up.
+ *
+ * @param cls the 'struct GNUNET_CLIENT_TestHandle'
+ * @param tc scheduler context
  */
 static void
-service_test_error (struct GNUNET_SCHEDULER_Handle *s,
-                    GNUNET_SCHEDULER_Task task, void *task_cls)
+report_result (void *cls,
+              const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
-  GNUNET_SCHEDULER_add_continuation (s,
-                                     task,
-                                     task_cls,
-                                     GNUNET_SCHEDULER_REASON_TIMEOUT);
+  struct GNUNET_CLIENT_TestHandle *th = cls;
+  
+  th->task = GNUNET_SCHEDULER_NO_TASK;
+  th->cb (th->cb_cls, th->result);
+  GNUNET_CLIENT_service_test_cancel (th);
+}
+
+
+/**
+ * Report service test result asynchronously back to callback.
+ *
+ * @param th test handle with the result and the callback
+ * @param result result to report
+ */
+static void
+service_test_report (struct GNUNET_CLIENT_TestHandle *th,
+                    int result)
+{
+  th->result = result;
+  th->task = GNUNET_SCHEDULER_add_now (&report_result,
+                                      th);                                    
 }
 
 
 /**
  * Receive confirmation from test, service is up.
  *
- * @param cls closure
+ * @param cls closure with the 'struct GNUNET_CLIENT_TestHandle'
  * @param msg message received, NULL on timeout or fatal error
  */
 static void
 confirm_handler (void *cls, const struct GNUNET_MessageHeader *msg)
 {
-  struct GNUNET_CLIENT_Connection *conn = cls;
+  struct GNUNET_CLIENT_TestHandle *th = cls;
+
   /* We may want to consider looking at the reply in more
-     detail in the future, for example, is this the
-     correct service? FIXME! */
-  if (msg != NULL)
-    {
-#if DEBUG_CLIENT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  "Received confirmation that service is running.\n");
-#endif
-      GNUNET_SCHEDULER_add_continuation (conn->sched,
-                                         conn->test_cb,
-                                         conn->test_cb_cls,
-                                         GNUNET_SCHEDULER_REASON_PREREQ_DONE);
-    }
+   * detail in the future, for example, is this the
+   * correct service? FIXME! */
+  if (NULL != msg)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Received confirmation that service is running.\n");
+    service_test_report (th, GNUNET_YES);
+  }
   else
-    {
-      service_test_error (conn->sched, conn->test_cb, conn->test_cb_cls);
-    }
-  GNUNET_CLIENT_disconnect (conn);
+  {
+    service_test_report (th, GNUNET_NO);
+  }
 }
 
 
+/**
+ * Send the 'TEST' message to the service.  If successful, prepare to
+ * receive the reply.
+ *
+ * @param cls the 'struct GNUNET_CLIENT_TestHandle' of the test
+ * @param size number of bytes available in buf
+ * @param buf where to write the message
+ * @return number of bytes written to buf
+ */
 static size_t
 write_test (void *cls, size_t size, void *buf)
 {
+  struct GNUNET_CLIENT_TestHandle *th = cls;
   struct GNUNET_MessageHeader *msg;
 
+  th->th = NULL;
   if (size < sizeof (struct GNUNET_MessageHeader))
-    {
-#if DEBUG_CLIENT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _("Failure to transmit TEST request.\n"));
-#endif
-      return 0;                 /* client disconnected */
-    }
-#if DEBUG_CLIENT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-             "Transmitting `%s' request.\n",
-             "TEST");
-#endif
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG, 
+        "Failed to transmit TEST request.\n");
+    service_test_report (th, GNUNET_NO);
+    return 0;                   /* client disconnected */
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG, 
+       "Transmitting `%s' request.\n", 
+       "TEST");
   msg = (struct GNUNET_MessageHeader *) buf;
   msg->type = htons (GNUNET_MESSAGE_TYPE_TEST);
   msg->size = htons (sizeof (struct GNUNET_MessageHeader));
+  GNUNET_CLIENT_receive (th->client, 
+                        &confirm_handler, th,
+                         GNUNET_TIME_absolute_get_remaining
+                         (th->test_deadline));
   return sizeof (struct GNUNET_MessageHeader);
 }
 
 
 /**
- * Wait until the service is running.
+ * Test if the service is running.  If we are given a UNIXPATH or a
+ * local address, we do this NOT by trying to connect to the service,
+ * but by trying to BIND to the same port.  If the BIND fails, we know
+ * the service is running.
  *
- * @param sched scheduler to use
  * @param service name of the service to wait for
  * @param cfg configuration to use
- * @param timeout how long to wait at most in ms
- * @param task task to run if service is running
- *        (reason will be "PREREQ_DONE" (service running)
- *         or "TIMEOUT" (service not known to be running))
- * @param task_cls closure for task
+ * @param timeout how long to wait at most
+ * @param cb function to call with the result
+ * @param cb_cls closure for 'cb'
+ * @return handle to cancel the test
  */
-void
-GNUNET_CLIENT_service_test (struct GNUNET_SCHEDULER_Handle *sched,
-                            const char *service,
+struct GNUNET_CLIENT_TestHandle *
+GNUNET_CLIENT_service_test (const char *service,
                             const struct GNUNET_CONFIGURATION_Handle *cfg,
                             struct GNUNET_TIME_Relative timeout,
-                            GNUNET_SCHEDULER_Task task, void *task_cls)
+                            GNUNET_CLIENT_TestResultCallback cb, void *cb_cls)
 {
-  struct GNUNET_CLIENT_Connection *conn;
+  struct GNUNET_CLIENT_TestHandle *th;
+  char *hostname;
+  unsigned long long port;
+  struct GNUNET_NETWORK_Handle *sock;
+
+  th = GNUNET_new (struct GNUNET_CLIENT_TestHandle);
+  th->cb = cb;
+  th->cb_cls = cb_cls;
+  th->test_deadline = GNUNET_TIME_relative_to_absolute (timeout);
+  LOG (GNUNET_ERROR_TYPE_DEBUG, 
+       "Testing if service `%s' is running.\n",
+       service);
+#ifdef AF_UNIX
+  {
+    /* probe UNIX support */
+    struct sockaddr_un s_un;
+    size_t slen;
+    char *unixpath;
+
+    unixpath = NULL;
+    if ((GNUNET_OK == GNUNET_CONFIGURATION_get_value_string (cfg, service, "UNIXPATH", &unixpath)) && (0 < strlen (unixpath)))  /* We have a non-NULL unixpath, does that mean it's valid? */
+    {
+      if (strlen (unixpath) >= sizeof (s_un.sun_path))
+      {
+        LOG (GNUNET_ERROR_TYPE_WARNING,
+             _("UNIXPATH `%s' too long, maximum length is %llu\n"), unixpath,
+             (unsigned long long) sizeof (s_un.sun_path));
+       unixpath = GNUNET_NETWORK_shorten_unixpath (unixpath);
+        LOG (GNUNET_ERROR_TYPE_INFO,
+             _("Using `%s' instead\n"), unixpath);
+      }
+    }
+    if (NULL != unixpath)
+    {
+      sock = GNUNET_NETWORK_socket_create (PF_UNIX, SOCK_STREAM, 0);
+      if (NULL != sock)
+      {
+       memset (&s_un, 0, sizeof (s_un));
+       s_un.sun_family = AF_UNIX;
+       slen = strlen (unixpath) + 1;
+       if (slen >= sizeof (s_un.sun_path))
+         slen = sizeof (s_un.sun_path) - 1;
+       memcpy (s_un.sun_path, unixpath, slen);
+       s_un.sun_path[slen] = '\0';
+       slen = sizeof (struct sockaddr_un);
+#if LINUX
+       s_un.sun_path[0] = '\0';
+#endif
+#if HAVE_SOCKADDR_IN_SIN_LEN
+       s_un.sun_len = (u_char) slen;
+#endif
+       if (GNUNET_OK !=
+           GNUNET_NETWORK_socket_bind (sock, (const struct sockaddr *) &s_un,
+                                       slen, GNUNET_BIND_EXCLUSIVE))
+        {
+         /* failed to bind => service must be running */
+         GNUNET_free (unixpath);
+         (void) GNUNET_NETWORK_socket_close (sock);
+         service_test_report (th, GNUNET_YES);
+         return th;
+       }
+       (void) GNUNET_NETWORK_socket_close (sock);        
+        /* let's try IP */
+      }
+    }
+    GNUNET_free_non_null (unixpath);
+  }
+#endif
 
-#if DEBUG_CLIENT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "Testing if service `%s' is running.\n", service);
+  hostname = NULL;
+  if ((GNUNET_OK !=
+       GNUNET_CONFIGURATION_get_value_number (cfg, service, "PORT", &port)) ||
+      (port > 65535) ||
+      (GNUNET_OK !=
+       GNUNET_CONFIGURATION_get_value_string (cfg, service, "HOSTNAME",
+                                              &hostname)))
+  {
+    /* UNIXPATH failed (if possible) AND IP failed => error */
+    service_test_report (th, GNUNET_SYSERR);
+    return th;
+  }
+
+  if (0 == strcmp ("localhost", hostname)
+#if !LINUX
+      && 0
+#endif
+      )
+  {
+    /* can test using 'bind' */
+    struct sockaddr_in s_in;
+
+    memset (&s_in, 0, sizeof (s_in));
+#if HAVE_SOCKADDR_IN_SIN_LEN
+    s_in.sin_len = sizeof (struct sockaddr_in);
 #endif
-  conn = GNUNET_CLIENT_connect (sched, service, cfg);
-  if (conn == NULL)
+    s_in.sin_family = AF_INET;
+    s_in.sin_port = htons (port);
+
+    sock = GNUNET_NETWORK_socket_create (AF_INET, SOCK_STREAM, 0);
+    if (NULL != sock)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                  _
-                  ("Could not connect to service `%s', must not be running.\n"),
-                  service);
-      service_test_error (sched, task, task_cls);
-      return;
+      if (GNUNET_OK !=
+          GNUNET_NETWORK_socket_bind (sock, (const struct sockaddr *) &s_in,
+                                      sizeof (s_in), GNUNET_BIND_EXCLUSIVE))
+      {
+        /* failed to bind => service must be running */
+        GNUNET_free (hostname);
+        (void) GNUNET_NETWORK_socket_close (sock);
+        service_test_report (th, GNUNET_YES);
+        return th;
+      }
+      (void) GNUNET_NETWORK_socket_close (sock);
     }
-  conn->test_cb = task;
-  conn->test_cb_cls = task_cls;
-  if (NULL ==
-      GNUNET_CONNECTION_notify_transmit_ready (conn->sock,
-                                               sizeof (struct
-                                                       GNUNET_MessageHeader),
-                                               timeout, &write_test, NULL))
+  }
+
+  if (0 == strcmp ("ip6-localhost", hostname)
+#if !LINUX
+      && 0
+#endif
+      )
+  {
+    /* can test using 'bind' */
+    struct sockaddr_in6 s_in6;
+
+    memset (&s_in6, 0, sizeof (s_in6));
+#if HAVE_SOCKADDR_IN_SIN_LEN
+    s_in6.sin6_len = sizeof (struct sockaddr_in6);
+#endif
+    s_in6.sin6_family = AF_INET6;
+    s_in6.sin6_port = htons (port);
+
+    sock = GNUNET_NETWORK_socket_create (AF_INET6, SOCK_STREAM, 0);
+    if (NULL != sock)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("Failure to transmit request to service `%s'\n"),
-                  service);
-      service_test_error (sched, task, task_cls);
-      GNUNET_CLIENT_disconnect (conn);
-      return;
+      if (GNUNET_OK !=
+          GNUNET_NETWORK_socket_bind (sock, (const struct sockaddr *) &s_in6,
+                                      sizeof (s_in6), GNUNET_BIND_EXCLUSIVE))
+      {
+        /* failed to bind => service must be running */
+        GNUNET_free (hostname);
+        (void) GNUNET_NETWORK_socket_close (sock);
+        service_test_report (th, GNUNET_YES);
+        return th;
+      }
+      (void) GNUNET_NETWORK_socket_close (sock);
     }
-  GNUNET_CLIENT_receive (conn, &confirm_handler, conn, timeout);
+  }
+
+  if (((0 == strcmp ("localhost", hostname)) ||
+       (0 == strcmp ("ip6-localhost", hostname)))
+#if !LINUX
+      && 0
+#endif
+      )
+  {
+    /* all binds succeeded => claim service not running right now */
+    GNUNET_free_non_null (hostname);
+    service_test_report (th, GNUNET_NO);
+    return th;
+  }
+  GNUNET_free_non_null (hostname);
+
+  /* non-localhost, try 'connect' method */
+  th->client = GNUNET_CLIENT_connect (service, cfg);
+  if (NULL == th->client)
+  {
+    LOG (GNUNET_ERROR_TYPE_INFO,
+         _("Could not connect to service `%s', configuration broken.\n"),
+         service);
+    service_test_report (th, GNUNET_SYSERR);
+    return th;
+  }
+  th->th = GNUNET_CLIENT_notify_transmit_ready (th->client,
+                                               sizeof (struct GNUNET_MessageHeader),
+                                               timeout, GNUNET_YES,
+                                               &write_test, th);
+  if (NULL == th->th)
+  {
+    LOG (GNUNET_ERROR_TYPE_WARNING,
+         _("Failure to transmit request to service `%s'\n"), service);
+    service_test_report (th, GNUNET_SYSERR);
+    return th;
+  }
+  return th;
 }
 
 
@@ -685,7 +1008,8 @@ GNUNET_CLIENT_service_test (struct GNUNET_SCHEDULER_Handle *sched,
  * @param buf where to write them
  * @return number of bytes written to buf
  */
-static size_t client_notify (void *cls, size_t size, void *buf);
+static size_t
+client_notify (void *cls, size_t size, void *buf);
 
 
 /**
@@ -696,41 +1020,60 @@ static size_t client_notify (void *cls, size_t size, void *buf);
  * @param tc unused
  */
 static void
-client_delayed_retry (void *cls,
-                      const struct GNUNET_SCHEDULER_TaskContext *tc)
+client_delayed_retry (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
   struct GNUNET_CLIENT_TransmitHandle *th = cls;
-
+  struct GNUNET_TIME_Relative delay;
+  
   th->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
   if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
-    {
-#if DEBUG_CLIENT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Transmission failed due to shutdown.\n");
-#endif
-      th->notify (th->notify_cls, 0, NULL);
-      GNUNET_free (th);
-      return;
-    }
-  th->th = GNUNET_CONNECTION_notify_transmit_ready (th->sock->sock,
-                                                    th->size,
-                                                    GNUNET_TIME_absolute_get_remaining
-                                                    (th->timeout),
-                                                    &client_notify, th);
-  if (th->th == NULL)
-    {
-      GNUNET_break (0);
-      th->notify (th->notify_cls, 0, NULL);
-      GNUNET_free (th);
-      return;
-    }
+  {
+    /* give up, was shutdown */
+    th->client->th = NULL;
+    th->notify (th->notify_cls, 0, NULL);
+    GNUNET_free (th);
+    return;
+  }
+  th->client->connection =
+      do_connect (th->client->service_name, th->client->cfg, th->client->attempts++);
+  th->client->first_message = GNUNET_YES;
+  if (NULL == th->client->connection)
+  {
+    /* could happen if we're out of sockets */
+    delay =
+        GNUNET_TIME_relative_min (GNUNET_TIME_absolute_get_remaining
+                                  (th->timeout), th->client->back_off);
+    th->client->back_off =
+        GNUNET_TIME_relative_min (GNUNET_TIME_relative_multiply
+                                  (th->client->back_off, 2),
+                                  GNUNET_TIME_UNIT_SECONDS);
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Transmission failed %u times, trying again in %s.\n",
+         MAX_ATTEMPTS - th->attempts_left,
+         GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES));
+    th->reconnect_task =
+        GNUNET_SCHEDULER_add_delayed (delay, &client_delayed_retry, th);
+    return;
+  }
+  th->th =
+      GNUNET_CONNECTION_notify_transmit_ready (th->client->connection, th->size,
+                                               GNUNET_TIME_absolute_get_remaining
+                                               (th->timeout), &client_notify,
+                                               th);
+  if (NULL == th->th)
+  {
+    GNUNET_break (0);
+    th->client->th = NULL;
+    th->notify (th->notify_cls, 0, NULL);
+    GNUNET_free (th);
+    return;
+  }
 }
 
 
 /**
- * Connection notifies us about failure or success of
- * a transmission request.  Either pass it on to our
- * user or, if possible, retry.
+ * Connection notifies us about failure or success of a transmission
+ * request.  Either pass it on to our user or, if possible, retry.
  *
  * @param cls our "struct GNUNET_CLIENT_TransmissionHandle"
  * @param size number of bytes available for transmission
@@ -741,48 +1084,53 @@ static size_t
 client_notify (void *cls, size_t size, void *buf)
 {
   struct GNUNET_CLIENT_TransmitHandle *th = cls;
+  struct GNUNET_CLIENT_Connection *client = th->client;
   size_t ret;
   struct GNUNET_TIME_Relative delay;
 
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "client_notify is running\n");
   th->th = NULL;
-  th->sock->th = NULL;
-  if (buf == NULL)
+  client->th = NULL;
+  if (NULL == buf)
+  {
+    delay = GNUNET_TIME_absolute_get_remaining (th->timeout);
+    delay.rel_value_us /= 2;
+    if ((GNUNET_YES != th->auto_retry) || (0 == --th->attempts_left) ||
+        (delay.rel_value_us < 1)||
+       (0 != (GNUNET_SCHEDULER_get_reason() & GNUNET_SCHEDULER_REASON_SHUTDOWN)))
     {
-      // FIXME: need a way to check if the
-      // reason is SHUTDOWN (not timeout) and
-      // if so NOT retry!
-      delay = GNUNET_TIME_absolute_get_remaining (th->timeout);
-      delay.value /= 2;
-      if ((GNUNET_YES != th->auto_retry) ||
-          (0 == --th->attempts_left) || (delay.value < 1))
-        {
-#if DEBUG_CLIENT
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Transmission failed %u times, giving up.\n",
-                     MAX_ATTEMPTS - th->attempts_left);
-#endif
-          GNUNET_break (0 == th->notify (th->notify_cls, 0, NULL));
-          GNUNET_free (th);
-          return 0;
-        }
-      /* auto-retry */
-      GNUNET_CONNECTION_destroy (th->sock->sock);
-      th->sock->sock = do_connect (th->sock->sched,
-                                   th->sock->service_name, th->sock->cfg);
-      GNUNET_assert (NULL != th->sock->sock);
-      delay = GNUNET_TIME_relative_min (delay, GNUNET_TIME_UNIT_SECONDS);
-#if DEBUG_CLIENT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                 "Transmission failed %u times, trying again in %llums.\n",
-                 MAX_ATTEMPTS - th->attempts_left,
-                 (unsigned long long) delay.value);
-#endif
-      th->reconnect_task = GNUNET_SCHEDULER_add_delayed (th->sock->sched,
-                                                        delay,
-                                                        &client_delayed_retry, th);
-      th->sock->th = th;
+      LOG (GNUNET_ERROR_TYPE_DEBUG,
+           "Transmission failed %u times, giving up.\n",
+           MAX_ATTEMPTS - th->attempts_left);
+      GNUNET_break (0 == th->notify (th->notify_cls, 0, NULL));
+      GNUNET_free (th);
       return 0;
     }
+    /* auto-retry */
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Failed to connect to `%s', automatically trying again.\n",
+         client->service_name);
+    if (GNUNET_YES == client->in_receive)
+    {
+      GNUNET_CONNECTION_receive_cancel (client->connection);
+      client->in_receive = GNUNET_NO;
+    }    
+    GNUNET_CONNECTION_destroy (client->connection);
+    client->connection = NULL;
+    delay = GNUNET_TIME_relative_min (delay, client->back_off);
+    client->back_off =
+        GNUNET_TIME_relative_min (GNUNET_TIME_relative_multiply
+                                  (client->back_off, 2),
+                                  GNUNET_TIME_UNIT_SECONDS);
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Transmission failed %u times, trying again in %s.\n",
+         MAX_ATTEMPTS - th->attempts_left,
+         GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES));
+    client->th = th;
+    th->reconnect_task =
+        GNUNET_SCHEDULER_add_delayed (delay, &client_delayed_retry, th);
+    return 0;
+  }
   GNUNET_assert (size >= th->size);
   ret = th->notify (th->notify_cls, size, buf);
   GNUNET_free (th);
@@ -795,7 +1143,7 @@ client_notify (void *cls, size_t size, void *buf)
  * are free in the transmission buffer.  May call the notify
  * method immediately if enough space is available.
  *
- * @param sock connection to the service
+ * @param client connection to the service
  * @param size number of bytes to send
  * @param timeout after how long should we give up (and call
  *        notify with buf NULL and size 0)?
@@ -810,7 +1158,7 @@ client_notify (void *cls, size_t size, void *buf)
  *         a handle if the notify callback was queued (can be used to cancel)
  */
 struct GNUNET_CLIENT_TransmitHandle *
-GNUNET_CLIENT_notify_transmit_ready (struct GNUNET_CLIENT_Connection *sock,
+GNUNET_CLIENT_notify_transmit_ready (struct GNUNET_CLIENT_Connection *client,
                                      size_t size,
                                      struct GNUNET_TIME_Relative timeout,
                                      int auto_retry,
@@ -819,52 +1167,69 @@ GNUNET_CLIENT_notify_transmit_ready (struct GNUNET_CLIENT_Connection *sock,
 {
   struct GNUNET_CLIENT_TransmitHandle *th;
 
-  if (NULL != sock->th)
+  if (NULL != client->th)
+  {
+    /* If this breaks, you most likley called this function twice without waiting
+     * for completion or canceling the request */
+    GNUNET_break (0);
     return NULL;
+  }
   th = GNUNET_malloc (sizeof (struct GNUNET_CLIENT_TransmitHandle));
-  th->sock = sock;
+  th->client = client;
   th->size = size;
   th->timeout = GNUNET_TIME_relative_to_absolute (timeout);
-  th->auto_retry = auto_retry;
+  /* always auto-retry on first message to service */
+  th->auto_retry = (GNUNET_YES == client->first_message) ? GNUNET_YES : auto_retry;
+  client->first_message = GNUNET_NO;
   th->notify = notify;
   th->notify_cls = notify_cls;
   th->attempts_left = MAX_ATTEMPTS;
-  th->th = GNUNET_CONNECTION_notify_transmit_ready (sock->sock,
-                                                    size,
-                                                    timeout,
-                                                    &client_notify, th);
-  if (NULL == th->th)
+  client->th = th;
+  if (NULL == client->connection)
+  {
+    th->reconnect_task =
+        GNUNET_SCHEDULER_add_delayed (client->back_off, &client_delayed_retry,
+                                      th);
+
+  }
+  else
+  {
+    th->th =
+        GNUNET_CONNECTION_notify_transmit_ready (client->connection, size, timeout,
+                                                 &client_notify, th);
+    if (NULL == th->th)
     {
       GNUNET_break (0);
       GNUNET_free (th);
+      client->th = NULL;
       return NULL;
     }
-  sock->th = th;
+  }
   return th;
 }
 
 
 /**
  * Cancel a request for notification.
- * 
+ *
  * @param th handle from the original request.
  */
 void
-GNUNET_CLIENT_notify_transmit_ready_cancel (struct
-                                            GNUNET_CLIENT_TransmitHandle *th)
+GNUNET_CLIENT_notify_transmit_ready_cancel (struct GNUNET_CLIENT_TransmitHandle
+                                            *th)
 {
-  if (th->reconnect_task != GNUNET_SCHEDULER_NO_TASK)
-    {
-      GNUNET_break (NULL == th->th);
-      GNUNET_SCHEDULER_cancel (th->sock->sched, th->reconnect_task);
-      th->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
-    }
+  if (GNUNET_SCHEDULER_NO_TASK != th->reconnect_task)
+  {
+    GNUNET_assert (NULL == th->th);
+    GNUNET_SCHEDULER_cancel (th->reconnect_task);
+    th->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
+  }
   else
-    {
-      GNUNET_break (NULL != th->th);
-      GNUNET_CONNECTION_notify_transmit_ready_cancel (th->th);
-    }
-  th->sock->th = NULL;
+  {
+    GNUNET_assert (NULL != th->th);
+    GNUNET_CONNECTION_notify_transmit_ready_cancel (th->th);
+  }
+  th->client->th = NULL;
   GNUNET_free (th);
 }
 
@@ -886,19 +1251,20 @@ transmit_for_response (void *cls, size_t size, void *buf)
   struct TransmitGetResponseContext *tc = cls;
   uint16_t msize;
 
-  tc->sock->tag = NULL;
+  tc->client->tag = NULL;
   msize = ntohs (tc->hdr->size);
   if (NULL == buf)
-    {
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         _("Could not submit request, not expecting to receive a response.\n"));
+    if (NULL != tc->rn)
       tc->rn (tc->rn_cls, NULL);
-      GNUNET_free (tc);
-      return 0;
-    }
+    GNUNET_free (tc);
+    return 0;
+  }
   GNUNET_assert (size >= msize);
   memcpy (buf, tc->hdr, msize);
-  GNUNET_CLIENT_receive (tc->sock,
-                         tc->rn,
-                         tc->rn_cls,
+  GNUNET_CLIENT_receive (tc->client, tc->rn, tc->rn_cls,
                          GNUNET_TIME_absolute_get_remaining (tc->timeout));
   GNUNET_free (tc);
   return msize;
@@ -912,7 +1278,7 @@ transmit_for_response (void *cls, size_t size, void *buf)
  * will be called with a "NULL" response (in which
  * case the connection should probably be destroyed).
  *
- * @param sock connection to use
+ * @param client connection to use
  * @param hdr message to transmit
  * @param timeout when to give up (for both transmission
  *         and for waiting for a response)
@@ -922,15 +1288,13 @@ transmit_for_response (void *cls, size_t size, void *buf)
  *        if the caller does not care about temporary connection errors,
  *        for example because the protocol is stateless
  * @param rn function to call with the response
- * @param rn_cls closure for rn 
+ * @param rn_cls closure for rn
  * @return GNUNET_OK on success, GNUNET_SYSERR if a request
  *         is already pending
  */
 int
-GNUNET_CLIENT_transmit_and_get_response (struct GNUNET_CLIENT_Connection
-                                         *sock,
-                                         const struct GNUNET_MessageHeader
-                                         *hdr,
+GNUNET_CLIENT_transmit_and_get_response (struct GNUNET_CLIENT_Connection *client,
+                                         const struct GNUNET_MessageHeader *hdr,
                                          struct GNUNET_TIME_Relative timeout,
                                          int auto_retry,
                                          GNUNET_CLIENT_MessageHandler rn,
@@ -939,32 +1303,28 @@ GNUNET_CLIENT_transmit_and_get_response (struct GNUNET_CLIENT_Connection
   struct TransmitGetResponseContext *tc;
   uint16_t msize;
 
-  if (NULL != sock->th)
+  if (NULL != client->th)
     return GNUNET_SYSERR;
-  GNUNET_assert (sock->tag == NULL);
+  GNUNET_assert (NULL == client->tag);
   msize = ntohs (hdr->size);
   tc = GNUNET_malloc (sizeof (struct TransmitGetResponseContext) + msize);
-  tc->sock = sock;
+  tc->client = client;
   tc->hdr = (const struct GNUNET_MessageHeader *) &tc[1];
   memcpy (&tc[1], hdr, msize);
   tc->timeout = GNUNET_TIME_relative_to_absolute (timeout);
   tc->rn = rn;
   tc->rn_cls = rn_cls;
-  if (NULL == GNUNET_CLIENT_notify_transmit_ready (sock,
-                                                   msize,
-                                                   timeout,
-                                                   auto_retry,
-                                                   &transmit_for_response,
-                                                   tc))
-    {
-      GNUNET_break (0);
-      GNUNET_free (tc);
-      return GNUNET_SYSERR;
-    }
-  sock->tag = tc;
+  if (NULL ==
+      GNUNET_CLIENT_notify_transmit_ready (client, msize, timeout, auto_retry,
+                                           &transmit_for_response, tc))
+  {
+    GNUNET_break (0);
+    GNUNET_free (tc);
+    return GNUNET_SYSERR;
+  }
+  client->tag = tc;
   return GNUNET_OK;
 }
 
 
-
 /*  end of client.c */