preparations for fixing #4065
[oweals/gnunet.git] / src / util / client.c
index 72c83e29bf1e2c2b272d08426cc6ce474f2cae37..88c43d4a197d9641bd2bd4f2769232794a80a259 100644 (file)
@@ -1,10 +1,10 @@
 /*
      This file is part of GNUnet.
-     (C) 2001, 2002, 2006, 2008, 2009 Christian Grothoff (and other contributing authors)
+     Copyright (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
@@ -14,8 +14,8 @@
 
      You should have received a copy of the GNU General Public License
      along with GNUnet; see the file COPYING.  If not, write to the
-     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-     Boston, MA 02111-1307, USA.
+     Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+     Boston, MA 02110-1301, USA.
 */
 
 /**
  * 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"
+#include "gnunet_util_lib.h"
+#include "gnunet_socks.h"
 
 
 /**
@@ -52,7 +49,7 @@ 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.
@@ -60,7 +57,7 @@ struct GNUNET_CLIENT_TransmitHandle
   GNUNET_CONNECTION_TransmitReadyNotify notify;
 
   /**
-   * Closure for notify.
+   * Closure for @e notify.
    */
   void *notify_cls;
 
@@ -74,7 +71,7 @@ struct GNUNET_CLIENT_TransmitHandle
    * If we are re-trying and are delaying to do so,
    * handle to the scheduled task managing the delay.
    */
-  GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
 
   /**
    * Timeout for the operation overall.
@@ -112,7 +109,7 @@ struct TransmitGetResponseContext
   /**
    * Client handle.
    */
-  struct GNUNET_CLIENT_Connection *sock;
+  struct GNUNET_CLIENT_Connection *client;
 
   /**
    * Message to transmit; do not free, allocated
@@ -131,7 +128,7 @@ struct TransmitGetResponseContext
   GNUNET_CLIENT_MessageHandler rn;
 
   /**
-   * Closure for "rn".
+   * Closure for @e rn.
    */
   void *rn_cls;
 };
@@ -146,9 +143,9 @@ struct GNUNET_CLIENT_Connection
 {
 
   /**
-   * the socket handle, NULL if not live
+   * The connection handle, NULL if not live
    */
-  struct GNUNET_CONNECTION_Handle *sock;
+  struct GNUNET_CONNECTION_Handle *connection;
 
   /**
    * Our configuration.
@@ -172,7 +169,7 @@ struct GNUNET_CLIENT_Connection
   GNUNET_CLIENT_MessageHandler receiver_handler;
 
   /**
-   * Closure for receiver_handler.
+   * Closure for @e receiver_handler.
    */
   void *receiver_handler_cls;
 
@@ -182,26 +179,11 @@ struct GNUNET_CLIENT_Connection
    */
   struct GNUNET_CLIENT_TransmitHandle *th;
 
-  /**
-   * Handler for service test completion (NULL unless in service_test)
-   */
-  GNUNET_SCHEDULER_Task test_cb;
-
-  /**
-   * Deadline for calling 'test_cb'.
-   */
-  struct GNUNET_TIME_Absolute test_deadline;
-
   /**
    * 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;
+  struct GNUNET_SCHEDULER_Task * receive_task;
 
   /**
    * Buffer for received message.
@@ -236,10 +218,17 @@ struct GNUNET_CLIENT_Connection
 
   /**
    * Are we currently busy doing receive-processing?
-   * GNUNET_YES if so, GNUNET_NO if not.
+   * #GNUNET_YES if so, #GNUNET_NO if not. #GNUNET_SYSERR
+   * if the connection has failed (but we may not have
+   * closed the handle itself yet).
    */
   int in_receive;
 
+  /**
+   * Is this the first message we are sending to the service?
+   */
+  int first_message;
+
   /**
    * How often have we tried to connect?
    */
@@ -248,6 +237,92 @@ struct GNUNET_CLIENT_Connection
 };
 
 
+/**
+ * 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_filename (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);
+      if (NULL == unixpath)
+       return NULL;
+    }
+    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_filename (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.
  *
@@ -258,34 +333,25 @@ struct GNUNET_CLIENT_Connection
  */
 static struct GNUNET_CONNECTION_Handle *
 do_connect (const char *service_name,
-            const struct GNUNET_CONFIGURATION_Handle *cfg, unsigned int attempt)
+            const struct GNUNET_CONFIGURATION_Handle *cfg,
+           unsigned int attempt)
 {
-  struct GNUNET_CONNECTION_Handle *sock;
+  struct GNUNET_CONNECTION_Handle *connection;
   char *hostname;
-  char *unixpath;
   unsigned long long port;
 
-  sock = NULL;
-#if AF_UNIX
+  /* Never use a local source if a proxy is configured */
+  if (GNUNET_YES == GNUNET_SOCKS_check_service (service_name,cfg))
+    return GNUNET_SOCKS_do_connect (service_name,cfg);
+
+  connection = NULL;
   if (0 == (attempt % 2))
   {
-    /* on even rounds, try UNIX */
-    unixpath = NULL;
-    if ((GNUNET_OK == GNUNET_CONFIGURATION_get_value_string (cfg, service_name, "UNIXPATH", &unixpath)) && (0 < strlen (unixpath)))     /* We have a non-NULL unixpath, does that mean it's valid? */
-    {
-      sock = GNUNET_CONNECTION_create_from_connect_to_unixpath (cfg, unixpath);
-      if (sock != NULL)
-      {
-        LOG (GNUNET_ERROR_TYPE_DEBUG, "Connected to unixpath `%s'!\n",
-             unixpath);
-        GNUNET_free (unixpath);
-        return sock;
-      }
-    }
-    GNUNET_free_non_null (unixpath);
+    /* on even rounds, try UNIX first */
+    connection = try_unixpath (service_name, cfg);
+    if (NULL != connection)
+      return connection;
   }
-#endif
-
   if (GNUNET_YES ==
       GNUNET_CONFIGURATION_have_value (cfg, service_name, "PORT"))
   {
@@ -316,40 +382,24 @@ do_connect (const char *service_name,
     port = 0;
     hostname = NULL;
   }
-  if (port == 0)
+  if (0 == port)
   {
-#if AF_UNIX
-    if (0 != (attempt % 2))
+    /* if port is 0, try UNIX */
+    connection = try_unixpath (service_name, cfg);
+    if (NULL != connection)
     {
-      /* try UNIX */
-      unixpath = NULL;
-      if ((GNUNET_OK ==
-           GNUNET_CONFIGURATION_get_value_string (cfg, service_name, "UNIXPATH",
-                                                  &unixpath)) &&
-          (0 < strlen (unixpath)))
-      {
-        sock =
-            GNUNET_CONNECTION_create_from_connect_to_unixpath (cfg, unixpath);
-        if (sock != NULL)
-        {
-          GNUNET_free (unixpath);
-          GNUNET_free_non_null (hostname);
-          return sock;
-        }
-      }
-      GNUNET_free_non_null (unixpath);
+      GNUNET_free_non_null (hostname);
+      return connection;
     }
-#endif
     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;
   }
-
-  sock = GNUNET_CONNECTION_create_from_connect (cfg, hostname, port);
+  connection = GNUNET_CONNECTION_create_from_connect (cfg, hostname, port);
   GNUNET_free (hostname);
-  return sock;
+  return connection;
 }
 
 
@@ -364,17 +414,22 @@ struct GNUNET_CLIENT_Connection *
 GNUNET_CLIENT_connect (const char *service_name,
                        const struct GNUNET_CONFIGURATION_Handle *cfg)
 {
-  struct GNUNET_CLIENT_Connection *ret;
-  struct GNUNET_CONNECTION_Handle *sock;
-
-  sock = do_connect (service_name, cfg, 0);
-  ret = GNUNET_malloc (sizeof (struct GNUNET_CLIENT_Connection));
-  ret->attempts = 1;
-  ret->sock = sock;
-  ret->service_name = GNUNET_strdup (service_name);
-  ret->cfg = cfg;
-  ret->back_off = GNUNET_TIME_UNIT_MILLISECONDS;
-  return ret;
+  struct GNUNET_CLIENT_Connection *client;
+  struct GNUNET_CONNECTION_Handle *connection;
+
+  if (GNUNET_OK !=
+      test_service_configuration (service_name,
+                                 cfg))
+    return NULL;
+  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;
 }
 
 
@@ -389,119 +444,134 @@ GNUNET_CLIENT_connect (const char *service_name,
  * 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)
 {
-  if (sock->in_receive == GNUNET_YES)
+  if (GNUNET_YES == client->in_receive)
   {
-    GNUNET_CONNECTION_receive_cancel (sock->sock);
-    sock->in_receive = GNUNET_NO;
+    GNUNET_CONNECTION_receive_cancel (client->connection);
+    client->in_receive = GNUNET_NO;
   }
-  if (sock->th != NULL)
+  if (NULL != client->th)
   {
-    GNUNET_CLIENT_notify_transmit_ready_cancel (sock->th);
-    sock->th = NULL;
+    GNUNET_CLIENT_notify_transmit_ready_cancel (client->th);
+    client->th = NULL;
   }
-  if (NULL != sock->sock)
+  if (NULL != client->connection)
   {
-    GNUNET_CONNECTION_destroy (sock->sock, GNUNET_NO);
-    sock->sock = NULL;
+    GNUNET_CONNECTION_destroy (client->connection);
+    client->connection = NULL;
   }
-  if (sock->receive_task != GNUNET_SCHEDULER_NO_TASK)
+  if (NULL != client->receive_task)
   {
-    GNUNET_SCHEDULER_cancel (sock->receive_task);
-    sock->receive_task = GNUNET_SCHEDULER_NO_TASK;
+    GNUNET_SCHEDULER_cancel (client->receive_task);
+    client->receive_task = NULL;
   }
-  if (sock->tag != NULL)
+  if (NULL != client->tag)
   {
-    GNUNET_free (sock->tag);
-    sock->tag = NULL;
+    GNUNET_free (client->tag);
+    client->tag = NULL;
   }
-  sock->receiver_handler = NULL;
-  GNUNET_array_grow (sock->received_buf, sock->received_size, 0);
-  GNUNET_free (sock->service_name);
-  GNUNET_free (sock);
+  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;
 }
 
 
 /**
  * Callback function for data received from the network.  Note that
- * both "available" and "errCode" would be 0 if the read simply timed out.
+ * both @a available and @a errCode would be 0 if the read simply timed out.
  *
  * @param cls closure
  * @param buf pointer to received data
- * @param available number of bytes availabe in "buf",
+ * @param available number of bytes availabe in @a buf,
  *        possibly 0 (on errors)
  * @param addr address of the sender
- * @param addrlen size of addr
+ * @param addrlen size of @a addr
  * @param errCode value of errno (on errors receiving)
  */
 static void
-receive_helper (void *cls, const void *buf, size_t available,
-                const struct sockaddr *addr, socklen_t addrlen, int errCode)
+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 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, conn->sock %s, errCode `%s'\n",
-         (unsigned int) available, conn->sock == NULL ? "NULL" : "non-NULL",
+         "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 = conn->receiver_handler))
+    /* remember failure */
+    client->in_receive = GNUNET_SYSERR;
+    if (NULL != (receive_handler = client->receiver_handler))
     {
-      receive_handler_cls = conn->receiver_handler_cls;
-      conn->receiver_handler = NULL;
-      receive_handler (receive_handler_cls, NULL);
+      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... */
 
-
   /* 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.rel_value == 0)
+  remaining = GNUNET_TIME_absolute_get_remaining (client->receive_timeout);
+  if (0 == remaining.rel_value_us)
   {
     /* signal timeout! */
-    if (NULL != conn->receiver_handler)
-      conn->receiver_handler (conn->receiver_handler_cls, NULL);
+    if (NULL != (receive_handler = client->receiver_handler))
+    {
+      client->receiver_handler = NULL;
+      receive_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);
 }
 
 
@@ -512,30 +582,44 @@ receive_helper (void *cls, const void *buf, size_t available,
  * @param tc scheduler context
  */
 static void
-receive_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+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];
+  char mbuf[msize] GNUNET_ALIGN;
   struct GNUNET_MessageHeader *msg = (struct GNUNET_MessageHeader *) mbuf;
 
-  LOG (GNUNET_ERROR_TYPE_DEBUG, "Received message of type %u and size %u\n",
-       ntohs (cmsg->type), msize);
-  sock->receive_task = GNUNET_SCHEDULER_NO_TASK;
-  GNUNET_assert (GNUNET_YES == sock->msg_complete);
-  GNUNET_assert (sock->received_pos >= msize);
+  client->receive_task = NULL;
+  if ( (GNUNET_SYSERR == client->in_receive) &&
+       (GNUNET_YES != client->msg_complete) )
+  {
+    /* Connection failure, signal to caller! */
+    client->receiver_handler = NULL;
+    if (NULL != handler)
+      handler (handler_cls,
+               NULL);
+    return;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received message of type %u and size %u from %s service.\n",
+       ntohs (cmsg->type),
+       msize,
+       client->service_name);
+  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);
 }
 
@@ -543,80 +627,180 @@ 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 handler_cls closure for @a 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,
+GNUNET_CLIENT_receive (struct GNUNET_CLIENT_Connection *client,
+                       GNUNET_CLIENT_MessageHandler handler,
+                      void *handler_cls,
                        struct GNUNET_TIME_Relative timeout)
 {
-  if (sock->sock == NULL)
+  if (NULL == client->connection)
   {
     /* already disconnected, fail instantly! */
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+               "Client API violation for service `%s'\n",
+               client->service_name);
     GNUNET_break (0);           /* this should not happen in well-written code! */
     if (NULL != handler)
-      handler (handler_cls, NULL);
+      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)
+  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_SYSERR == client->in_receive) )
   {
-    GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == sock->receive_task);
-    sock->receive_task = GNUNET_SCHEDULER_add_now (&receive_task, sock);
+    GNUNET_assert (NULL == client->receive_task);
+    client->receive_task = GNUNET_SCHEDULER_add_now (&receive_task, client);
+    return;
   }
-  else
+  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);
+}
+
+
+/**
+ * Handle for a test to check if a service is running.
+ */
+struct GNUNET_CLIENT_TestHandle
+{
+  /**
+   * Function to call with the result of the test.
+   */
+  GNUNET_CLIENT_TestResultCallback cb;
+
+  /**
+   * Closure for @e 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 @e cb.
+   */
+  struct GNUNET_TIME_Absolute test_deadline;
+
+  /**
+   * ID of task used for asynchronous operations.
+   */
+  struct GNUNET_SCHEDULER_Task * task;
+
+  /**
+   * Final result to report back (once known).
+   */
+  int result;
+};
+
+
+/**
+ * Abort testing for service.
+ *
+ * @param th test handle
+ */
+void
+GNUNET_CLIENT_service_test_cancel (struct GNUNET_CLIENT_TestHandle *th)
+{
+  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 (NULL != th->task)
   {
-    GNUNET_assert (sock->in_receive == GNUNET_NO);
-    sock->in_receive = GNUNET_YES;
-    LOG (GNUNET_ERROR_TYPE_DEBUG, "calling GNUNET_CONNECTION_receive\n");
-    GNUNET_CONNECTION_receive (sock->sock, GNUNET_SERVER_MAX_MESSAGE_SIZE - 1,
-                               timeout, &receive_helper, sock);
+    GNUNET_SCHEDULER_cancel (th->task);
+    th->task = NULL;
   }
+  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 (GNUNET_SCHEDULER_Task task, void *task_cls)
+report_result (void *cls,
+              const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
-  GNUNET_SCHEDULER_add_continuation (task, task_cls,
-                                     GNUNET_SCHEDULER_REASON_TIMEOUT);
+  struct GNUNET_CLIENT_TestHandle *th = cls;
+
+  th->task = NULL;
+  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)
+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 (NULL != msg)
   {
     LOG (GNUNET_ERROR_TYPE_DEBUG,
          "Received confirmation that service is running.\n");
-    GNUNET_SCHEDULER_add_continuation (conn->test_cb, conn->test_cb_cls,
-                                       GNUNET_SCHEDULER_REASON_PREREQ_DONE);
+    service_test_report (th, GNUNET_YES);
   }
   else
   {
-    service_test_error (conn->test_cb, conn->test_cb_cls);
+    service_test_report (th, GNUNET_NO);
   }
-  GNUNET_CLIENT_disconnect (conn);
 }
 
 
@@ -624,109 +808,134 @@ confirm_handler (void *cls, const struct GNUNET_MessageHeader *msg)
  * Send the 'TEST' message to the service.  If successful, prepare to
  * receive the reply.
  *
- * @param cls the 'struct GNUNET_CLIENT_Connection' of the connection to test
- * @param size number of bytes available in buf
+ * @param cls the `struct GNUNET_CLIENT_TestHandle` of the test
+ * @param size number of bytes available in @a buf
  * @param buf where to write the message
- * @return number of bytes written to buf
+ * @return number of bytes written to @a buf
  */
 static size_t
 write_test (void *cls, size_t size, void *buf)
 {
-  struct GNUNET_CLIENT_Connection *conn = cls;
+  struct GNUNET_CLIENT_TestHandle *th = cls;
   struct GNUNET_MessageHeader *msg;
 
+  th->th = NULL;
   if (size < sizeof (struct GNUNET_MessageHeader))
   {
-    LOG (GNUNET_ERROR_TYPE_DEBUG, _("Failure to transmit TEST request.\n"));
-    service_test_error (conn->test_cb, conn->test_cb_cls);
-    GNUNET_CLIENT_disconnect (conn);
+    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");
+  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 (conn, &confirm_handler, conn,
+  GNUNET_CLIENT_receive (th->client,
+                        &confirm_handler, th,
                          GNUNET_TIME_absolute_get_remaining
-                         (conn->test_deadline));
+                         (th->test_deadline));
   return sizeof (struct GNUNET_MessageHeader);
 }
 
 
 /**
- * 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.
+ * 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 service name of the service to wait for
  * @param cfg configuration to use
  * @param timeout how long to wait at most
- * @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 cb function to call with the result
+ * @param cb_cls closure for @a cb
+ * @return handle to cancel the test
  */
-void
+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_TestHandle *th;
   char *hostname;
   unsigned long long port;
   struct GNUNET_NETWORK_Handle *sock;
-  struct GNUNET_CLIENT_Connection *conn;
 
-  LOG (GNUNET_ERROR_TYPE_DEBUG, "Testing if service `%s' is running.\n",
+  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;
+    int abstract;
 
     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 ((GNUNET_OK ==
+        GNUNET_CONFIGURATION_get_value_filename (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,
-             sizeof (s_un.sun_path));
+             _("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);
       }
-      else
+    }
+#ifdef LINUX
+    abstract = GNUNET_CONFIGURATION_get_value_yesno (cfg,
+                                                     "TESTING",
+                                                     "USE_ABSTRACT_SOCKETS");
+#else
+    abstract = GNUNET_NO;
+#endif
+    if ((NULL != unixpath) && (GNUNET_YES != abstract))
+    {
+      if (GNUNET_SYSERR == GNUNET_DISK_directory_create_for_file (unixpath))
+        GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
+                                  "mkdir", unixpath);
+    }
+    if (NULL != unixpath)
+    {
+      sock = GNUNET_NETWORK_socket_create (PF_UNIX, SOCK_STREAM, 0);
+      if (NULL != sock)
       {
-        sock = GNUNET_NETWORK_socket_create (PF_UNIX, SOCK_STREAM, 0);
-        if (sock != NULL)
-        {
-          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
+       memset (&s_un, 0, sizeof (s_un));
+       s_un.sun_family = AF_UNIX;
+        strncpy (s_un.sun_path, unixpath, sizeof (s_un.sun_path) - 1);
+        if (GNUNET_YES == abstract)
           s_un.sun_path[0] = '\0';
-#endif
 #if HAVE_SOCKADDR_IN_SIN_LEN
-          s_un.sun_len = (u_char) slen;
+        s_un.sun_len = (u_char) sizeof (struct sockaddr_un);
 #endif
-          if (GNUNET_OK !=
-              GNUNET_NETWORK_socket_bind (sock, (const struct sockaddr *) &s_un,
-                                          slen))
-          {
-            /* failed to bind => service must be running */
-            GNUNET_free (unixpath);
-            (void) GNUNET_NETWORK_socket_close (sock);
-            GNUNET_SCHEDULER_add_continuation (task, task_cls,
-                                               GNUNET_SCHEDULER_REASON_PREREQ_DONE);
-            return;
-          }
-          (void) GNUNET_NETWORK_socket_close (sock);
-        }
+       if (GNUNET_OK !=
+           GNUNET_NETWORK_socket_bind (sock, (const struct sockaddr *) &s_un,
+                                       sizeof (struct sockaddr_un)))
+        {
+         /* 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 */
       }
     }
@@ -743,8 +952,8 @@ GNUNET_CLIENT_service_test (const char *service,
                                               &hostname)))
   {
     /* UNIXPATH failed (if possible) AND IP failed => error */
-    service_test_error (task, task_cls);
-    return;
+    service_test_report (th, GNUNET_SYSERR);
+    return th;
   }
 
   if (0 == strcmp ("localhost", hostname)
@@ -764,7 +973,7 @@ GNUNET_CLIENT_service_test (const char *service,
     s_in.sin_port = htons (port);
 
     sock = GNUNET_NETWORK_socket_create (AF_INET, SOCK_STREAM, 0);
-    if (sock != NULL)
+    if (NULL != sock)
     {
       if (GNUNET_OK !=
           GNUNET_NETWORK_socket_bind (sock, (const struct sockaddr *) &s_in,
@@ -773,9 +982,8 @@ GNUNET_CLIENT_service_test (const char *service,
         /* failed to bind => service must be running */
         GNUNET_free (hostname);
         (void) GNUNET_NETWORK_socket_close (sock);
-        GNUNET_SCHEDULER_add_continuation (task, task_cls,
-                                           GNUNET_SCHEDULER_REASON_PREREQ_DONE);
-        return;
+        service_test_report (th, GNUNET_YES);
+        return th;
       }
       (void) GNUNET_NETWORK_socket_close (sock);
     }
@@ -798,7 +1006,7 @@ GNUNET_CLIENT_service_test (const char *service,
     s_in6.sin6_port = htons (port);
 
     sock = GNUNET_NETWORK_socket_create (AF_INET6, SOCK_STREAM, 0);
-    if (sock != NULL)
+    if (NULL != sock)
     {
       if (GNUNET_OK !=
           GNUNET_NETWORK_socket_bind (sock, (const struct sockaddr *) &s_in6,
@@ -807,9 +1015,8 @@ GNUNET_CLIENT_service_test (const char *service,
         /* failed to bind => service must be running */
         GNUNET_free (hostname);
         (void) GNUNET_NETWORK_socket_close (sock);
-        GNUNET_SCHEDULER_add_continuation (task, task_cls,
-                                           GNUNET_SCHEDULER_REASON_PREREQ_DONE);
-        return;
+        service_test_report (th, GNUNET_YES);
+        return th;
       }
       (void) GNUNET_NETWORK_socket_close (sock);
     }
@@ -824,37 +1031,33 @@ GNUNET_CLIENT_service_test (const char *service,
   {
     /* all binds succeeded => claim service not running right now */
     GNUNET_free_non_null (hostname);
-    service_test_error (task, task_cls);
-    return;
+    service_test_report (th, GNUNET_NO);
+    return th;
   }
   GNUNET_free_non_null (hostname);
 
   /* non-localhost, try 'connect' method */
-  conn = GNUNET_CLIENT_connect (service, cfg);
-  if (conn == NULL)
+  th->client = GNUNET_CLIENT_connect (service, cfg);
+  if (NULL == th->client)
   {
     LOG (GNUNET_ERROR_TYPE_INFO,
-         _("Could not connect to service `%s', must not be running.\n"),
+         _("Could not connect to service `%s', configuration broken.\n"),
          service);
-    service_test_error (task, task_cls);
-    return;
+    service_test_report (th, GNUNET_SYSERR);
+    return th;
   }
-  conn->test_cb = task;
-  conn->test_cb_cls = task_cls;
-  conn->test_deadline = GNUNET_TIME_relative_to_absolute (timeout);
-
-  if (NULL ==
-      GNUNET_CLIENT_notify_transmit_ready (conn,
-                                           sizeof (struct GNUNET_MessageHeader),
-                                           timeout, GNUNET_YES, &write_test,
-                                           conn))
+  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_error (task, task_cls);
-    GNUNET_CLIENT_disconnect (conn);
-    return;
+    service_test_report (th, GNUNET_SYSERR);
+    return th;
   }
+  return th;
 }
 
 
@@ -863,10 +1066,10 @@ GNUNET_CLIENT_service_test (const char *service,
  * a transmission request.  Either pass it on to our
  * user or, if possible, retry.
  *
- * @param cls our "struct GNUNET_CLIENT_TransmissionHandle"
+ * @param cls our `struct GNUNET_CLIENT_TransmissionHandle`
  * @param size number of bytes available for transmission
  * @param buf where to write them
- * @return number of bytes written to buf
+ * @return number of bytes written to @a buf
  */
 static size_t
 client_notify (void *cls, size_t size, void *buf);
@@ -876,53 +1079,55 @@ client_notify (void *cls, size_t size, void *buf);
  * This task is run if we should re-try connection to the
  * service after a while.
  *
- * @param cls our "struct GNUNET_CLIENT_TransmitHandle" of the request
+ * @param cls our `struct GNUNET_CLIENT_TransmitHandle` of the request
  * @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;
+  th->reconnect_task = NULL;
   if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
   {
-    LOG (GNUNET_ERROR_TYPE_DEBUG, "Transmission failed due to shutdown.\n");
-    th->sock->th = NULL;
+    /* give up, was shutdown */
+    th->client->th = NULL;
     th->notify (th->notify_cls, 0, NULL);
     GNUNET_free (th);
     return;
   }
-  th->sock->sock =
-      do_connect (th->sock->service_name, th->sock->cfg, th->sock->attempts++);
-  if (NULL == th->sock->sock)
+  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->sock->back_off);
-    th->sock->back_off =
-        GNUNET_TIME_relative_min (GNUNET_TIME_relative_multiply
-                                  (th->sock->back_off, 2),
-                                  GNUNET_TIME_UNIT_SECONDS);
+    delay = GNUNET_TIME_relative_min (GNUNET_TIME_absolute_get_remaining (th->timeout),
+                                      th->client->back_off);
+    th->client->back_off = GNUNET_TIME_STD_BACKOFF (th->client->back_off);
     LOG (GNUNET_ERROR_TYPE_DEBUG,
-         "Transmission failed %u times, trying again in %llums.\n",
+         "Transmission failed %u times, trying again in %s.\n",
          MAX_ATTEMPTS - th->attempts_left,
-         (unsigned long long) delay.rel_value);
+         GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES));
+    GNUNET_assert (NULL == th->th);
+    GNUNET_assert (NULL == th->reconnect_task);
     th->reconnect_task =
         GNUNET_SCHEDULER_add_delayed (delay, &client_delayed_retry, th);
     return;
   }
   th->th =
-      GNUNET_CONNECTION_notify_transmit_ready (th->sock->sock, th->size,
+      GNUNET_CONNECTION_notify_transmit_ready (th->client->connection, th->size,
                                                GNUNET_TIME_absolute_get_remaining
                                                (th->timeout), &client_notify,
                                                th);
-  if (th->th == NULL)
+  if (NULL == th->th)
   {
     GNUNET_break (0);
-    th->sock->th = NULL;
+    th->client->th = NULL;
     th->notify (th->notify_cls, 0, NULL);
     GNUNET_free (th);
     return;
@@ -934,52 +1139,65 @@ client_delayed_retry (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
  * 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 cls our `struct GNUNET_CLIENT_TransmissionHandle`
  * @param size number of bytes available for transmission
  * @param buf where to write them
- * @return number of bytes written to buf
+ * @return number of bytes written to @a buf
  */
 static size_t
-client_notify (void *cls, size_t size, void *buf)
+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 /= 2;
-    if ((0 !=
-         (GNUNET_SCHEDULER_REASON_SHUTDOWN & GNUNET_SCHEDULER_get_reason ())) ||
-        (GNUNET_YES != th->auto_retry) || (0 == --th->attempts_left) ||
-        (delay.rel_value < 1))
+    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)))
     {
       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_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",
-         th->sock->service_name);
-    GNUNET_CONNECTION_destroy (th->sock->sock, GNUNET_NO);
-    th->sock->sock = NULL;
-    delay = GNUNET_TIME_relative_min (delay, th->sock->back_off);
-    th->sock->back_off =
+         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
-                                  (th->sock->back_off, 2),
+                                  (client->back_off, 2),
                                   GNUNET_TIME_UNIT_SECONDS);
     LOG (GNUNET_ERROR_TYPE_DEBUG,
-         "Transmission failed %u times, trying again in %llums.\n",
+         "Transmission failed %u times, trying again in %s.\n",
          MAX_ATTEMPTS - th->attempts_left,
-         (unsigned long long) delay.rel_value);
-    th->sock->th = th;
+         GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES));
+    client->th = th;
+    GNUNET_assert (NULL == th->reconnect_task);
+    GNUNET_assert (NULL == th->th);
     th->reconnect_task =
         GNUNET_SCHEDULER_add_delayed (delay, &client_delayed_retry, th);
     return 0;
@@ -987,16 +1205,24 @@ client_notify (void *cls, size_t size, void *buf)
   GNUNET_assert (size >= th->size);
   ret = th->notify (th->notify_cls, size, buf);
   GNUNET_free (th);
+  if (sizeof (struct GNUNET_MessageHeader) <= ret)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Transmitting message of type %u and size %u to %s service.\n",
+         ntohs (((struct GNUNET_MessageHeader *) buf)->type),
+         ntohs (((struct GNUNET_MessageHeader *) buf)->size),
+         client->service_name);
+  }
   return ret;
 }
 
 
 /**
  * Ask the client to call us once the specified number of bytes
- * are free in the transmission buffer.  May call the notify
- * method immediately if enough space is available.
+ * are free in the transmission buffer.  Will never call the @a notify
+ * callback in this task, but always first go into the scheduler.
  *
- * @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)?
@@ -1006,53 +1232,59 @@ client_notify (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 notify function to call
- * @param notify_cls closure for notify
+ * @param notify_cls closure for @a notify
  * @return NULL if our buffer will never hold size bytes,
  *         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,
-                                     GNUNET_CONNECTION_TransmitReadyNotify
-                                     notify, void *notify_cls)
+                                     GNUNET_CONNECTION_TransmitReadyNotify notify,
+                                    void *notify_cls)
 {
   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);
+    GNUNET_assert (0);
     return NULL;
   }
-  th = GNUNET_malloc (sizeof (struct GNUNET_CLIENT_TransmitHandle));
-  th->sock = sock;
+  th = GNUNET_new (struct GNUNET_CLIENT_TransmitHandle);
+  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;
-  sock->th = th;
-  if (sock->sock == NULL)
+  client->th = th;
+  if (NULL == client->connection)
   {
+    GNUNET_assert (NULL == th->th);
+    GNUNET_assert (NULL == th->reconnect_task);
     th->reconnect_task =
-        GNUNET_SCHEDULER_add_delayed (sock->back_off, &client_delayed_retry,
+        GNUNET_SCHEDULER_add_delayed (client->back_off,
+                                      &client_delayed_retry,
                                       th);
-
   }
   else
   {
-    th->th =
-        GNUNET_CONNECTION_notify_transmit_ready (sock->sock, size, timeout,
-                                                 &client_notify, th);
+    th->th = GNUNET_CONNECTION_notify_transmit_ready (client->connection,
+                                                      size,
+                                                      timeout,
+                                                      &client_notify,
+                                                      th);
     if (NULL == th->th)
     {
       GNUNET_break (0);
       GNUNET_free (th);
-      sock->th = NULL;
+      client->th = NULL;
       return NULL;
     }
   }
@@ -1066,48 +1298,49 @@ GNUNET_CLIENT_notify_transmit_ready (struct GNUNET_CLIENT_Connection *sock,
  * @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)
+  if (NULL != th->reconnect_task)
   {
     GNUNET_assert (NULL == th->th);
     GNUNET_SCHEDULER_cancel (th->reconnect_task);
-    th->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
+    th->reconnect_task = NULL;
   }
   else
   {
     GNUNET_assert (NULL != th->th);
     GNUNET_CONNECTION_notify_transmit_ready_cancel (th->th);
   }
-  th->sock->th = NULL;
+  th->client->th = NULL;
   GNUNET_free (th);
 }
 
 
 /**
  * Function called to notify a client about the socket
- * begin ready to queue the message.  "buf" will be
- * NULL and "size" zero if the socket was closed for
+ * begin ready to queue the message.  @a buf will be
+ * NULL and @a size zero if the socket was closed for
  * writing in the meantime.
  *
- * @param cls closure of type "struct TransmitGetResponseContext*"
- * @param size number of bytes available in buf
+ * @param cls closure of type `struct TransmitGetResponseContext *`
+ * @param size number of bytes available in @a buf
  * @param buf where the callee should write the message
- * @return number of bytes written to buf
+ * @return number of bytes written to @a buf
  */
 static size_t
-transmit_for_response (void *cls, size_t size, void *buf)
+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"));
+         "Could not submit request, not expecting to receive a response.\n");
     if (NULL != tc->rn)
       tc->rn (tc->rn_cls, NULL);
     GNUNET_free (tc);
@@ -1115,7 +1348,9 @@ transmit_for_response (void *cls, size_t size, void *buf)
   }
   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;
@@ -1129,7 +1364,7 @@ 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)
@@ -1139,12 +1374,12 @@ 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
- * @return GNUNET_OK on success, GNUNET_SYSERR if a request
+ * @param rn_cls closure for @a 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,
+GNUNET_CLIENT_transmit_and_get_response (struct GNUNET_CLIENT_Connection *client,
                                          const struct GNUNET_MessageHeader *hdr,
                                          struct GNUNET_TIME_Relative timeout,
                                          int auto_retry,
@@ -1154,29 +1389,28 @@ GNUNET_CLIENT_transmit_and_get_response (struct GNUNET_CLIENT_Connection *sock,
   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,
+      GNUNET_CLIENT_notify_transmit_ready (client, msize, timeout, auto_retry,
                                            &transmit_for_response, tc))
   {
     GNUNET_break (0);
     GNUNET_free (tc);
     return GNUNET_SYSERR;
   }
-  sock->tag = tc;
+  client->tag = tc;
   return GNUNET_OK;
 }
 
 
-
 /*  end of client.c */