stuff
[oweals/gnunet.git] / src / transport / plugin_transport_tcp.c
index 7d104f371da36027091a7a5f738f1ae4a431adf1..e796dacf4ffe20cce4c1a2427ca7ca744153bda0 100644 (file)
  */
 #include "platform.h"
 #include "gnunet_hello_lib.h"
+#include "gnunet_constants.h"
 #include "gnunet_connection_lib.h"
 #include "gnunet_container_lib.h"
+#include "gnunet_nat_lib.h"
 #include "gnunet_os_lib.h"
 #include "gnunet_protocols.h"
 #include "gnunet_resolver_service.h"
 #include "gnunet_signatures.h"
 #include "gnunet_statistics_service.h"
 #include "gnunet_transport_service.h"
-#include "plugin_transport.h"
+#include "gnunet_transport_plugin.h"
 #include "transport.h"
 
-#define DEBUG_TCP GNUNET_YES
-#define DEBUG_TCP_NAT GNUNET_YES
-
-/**
- * How long until we give up on transmitting the welcome message?
- */
-#define HOSTNAME_RESOLVE_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
+#define DEBUG_TCP GNUNET_NO
 
+#define DEBUG_TCP_NAT GNUNET_NO
 
 /**
  * Initial handshake message for a session.
@@ -63,6 +60,7 @@ struct WelcomeMessage
 
 };
 
+
 /**
  * Basically a WELCOME message, but with the purpose
  * of giving the waiting peer a client handle to use
@@ -81,11 +79,23 @@ struct TCP_NAT_ProbeMessage
 
 };
 
+
 /**
  * Context for sending a NAT probe via TCP.
  */
 struct TCPProbeContext
 {
+
+  /**
+   * Active probes are kept in a DLL.
+   */
+  struct TCPProbeContext *next;
+
+  /**
+   * Active probes are kept in a DLL.
+   */
+  struct TCPProbeContext *prev;
+
   /**
    * Probe connection.
    */
@@ -121,7 +131,7 @@ struct IPv4TcpAddress
   /**
    * Port number, in network byte order.
    */
-  uint16_t t_port GNUNET_PACKED;
+  uint16_t t4_port GNUNET_PACKED;
 
 };
 
@@ -143,37 +153,13 @@ struct IPv6TcpAddress
 
 };
 
+
 /**
  * Encapsulation of all of the state of the plugin.
  */
 struct Plugin;
 
 
-/**
- * Local network addresses (actual IP address follows this struct).
- * PORT is NOT included!
- */
-struct LocalAddrList
-{
-
-  /**
-   * This is a doubly linked list.
-   */
-  struct LocalAddrList *next;
-
-  /**
-   * This is a doubly linked list.
-   */
-  struct LocalAddrList *prev;
-
-  /**
-   * Number of bytes of the address that follow
-   */
-  size_t size;
-
-};
-
-
 /**
  * Information kept for each message that is yet to
  * be transmitted.
@@ -328,24 +314,9 @@ struct Plugin
   struct GNUNET_CONNECTION_Handle *lsock;
 
   /**
-   * stdout pipe handle for the gnunet-nat-server process
-   */
-  struct GNUNET_DISK_PipeHandle *server_stdout;
-
-  /**
-   * stdout file handle (for reading) for the gnunet-nat-server process
-   */
-  const struct GNUNET_DISK_FileHandle *server_stdout_handle;
-
-  /**
-   * ID of select gnunet-nat-server stdout read task
-   */
-  GNUNET_SCHEDULER_TaskIdentifier server_read_task;
-
-  /**
-   * The process id of the server process (if behind NAT)
+   * Our handle to the NAT module.
    */
-  pid_t server_pid;
+  struct GNUNET_NAT_Handle *nat;
 
   /**
    * List of open TCP sessions.
@@ -368,41 +339,30 @@ struct Plugin
    */
   struct GNUNET_SERVER_MessageHandler *handlers;
 
-  /**
-   * Handle for request of hostname resolution, non-NULL if pending.
-   */
-  struct GNUNET_RESOLVER_RequestHandle *hostname_dns;
-
   /**
    * Map of peers we have tried to contact behind a NAT
    */
   struct GNUNET_CONTAINER_MultiHashMap *nat_wait_conns;
-
-  /**
-   * The external address given to us by the user.  Must be actual
-   * outside visible address for NAT punching to work.
-   */
-  char *external_address;
-
+  
   /**
-   * The internal address given to us by the user (or discovered).
+   * List of active TCP probes.
    */
-  char *internal_address;
+  struct TCPProbeContext *probe_head;
 
   /**
-   * Address given for us to bind to (ONLY).
+   * List of active TCP probes.
    */
-  char *bind_address;
+  struct TCPProbeContext *probe_tail;
 
   /**
-   * List of our IP addresses.
+   * Handle for (DYN)DNS lookup of our external IP.
    */
-  struct LocalAddrList *lal_head;
-
+  struct GNUNET_RESOLVER_RequestHandle *ext_dns;
+  
   /**
-   * Tail of our IP address list.
+   * How many more TCP sessions are we allowed to open right now?
    */
-  struct LocalAddrList *lal_tail;
+  unsigned long long max_connections;
 
   /**
    * ID of task used to update our addresses when one expires.
@@ -420,66 +380,89 @@ struct Plugin
    */
   uint16_t adv_port;
 
-  /**
-   * Is this transport configured to be behind a NAT?
-   */
-  int behind_nat;
-
-  /**
-   * Is this transport configured to allow connections to NAT'd peers?
-   */
-  int allow_nat;
-
-  /**
-   * Should this transport advertise only NAT addresses (port set to 0)?
-   * If not, all addresses will be duplicated for NAT punching and regular
-   * ports.
-   */
-  int only_nat_addresses;
-
 };
 
 
-static void
-add_to_address_list (struct Plugin *plugin,
-                    const void *arg,
-                    size_t arg_size)
+/**
+ * Function to check if an inbound connection is acceptable.
+ * Mostly used to limit the total number of open connections 
+ * we can have.
+ *
+ * @param cls the 'struct Plugin'
+ * @param ucred credentials, if available, otherwise NULL
+ * @param addr address
+ * @param addrlen length of address
+ * @return GNUNET_YES to allow, GNUNET_NO to deny, GNUNET_SYSERR
+ *   for unknown address family (will be denied).
+ */
+static int
+plugin_tcp_access_check (void *cls,
+                        const struct GNUNET_CONNECTION_Credentials *ucred,
+                        const struct sockaddr *addr,
+                        socklen_t addrlen)
 {
-  struct LocalAddrList *lal;
+  struct Plugin *plugin = cls;
 
-  lal = plugin->lal_head;
-  while (NULL != lal)
-    {
-      if ( (lal->size == arg_size) &&
-          (0 == memcmp (&lal[1], arg, arg_size)) )
-       return;
-      lal = lal->next;
-    }
-  lal = GNUNET_malloc (sizeof (struct LocalAddrList) + arg_size);
-  lal->size = arg_size;
-  memcpy (&lal[1], arg, arg_size);
-  GNUNET_CONTAINER_DLL_insert (plugin->lal_head,
-                              plugin->lal_tail,
-                              lal);
+  if (0 == plugin->max_connections)
+    return GNUNET_NO;
+  plugin->max_connections--;
+  return GNUNET_YES;
 }
 
 
-static int
-check_local_addr (struct Plugin *plugin,
-                 const void *arg,
-                 size_t arg_size)
+/**
+ * Our external IP address/port mapping has changed.
+ *
+ * @param cls closure, the 'struct LocalAddrList'
+ * @param add_remove GNUNET_YES to mean the new public IP address, GNUNET_NO to mean
+ *     the previous (now invalid) one
+ * @param addr either the previous or the new public IP address
+ * @param addrlen actual lenght of the address
+ */
+static void
+tcp_nat_port_map_callback (void *cls,
+                          int add_remove,
+                          const struct sockaddr *addr,
+                          socklen_t addrlen)
 {
-  struct LocalAddrList *lal;
+  struct Plugin *plugin = cls;
+  struct IPv4TcpAddress t4;
+  struct IPv6TcpAddress t6;
+  void *arg;
+  size_t args;
 
-  lal = plugin->lal_head;
-  while (NULL != lal)
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  "NPMC called with %d for address `%s'\n",
+                  add_remove,
+                  GNUNET_a2s (addr, addrlen));
+  /* convert 'addr' to our internal format */
+  switch (addr->sa_family)
     {
-      if ( (lal->size == arg_size) &&
-          (0 == memcmp (&lal[1], arg, arg_size)) )
-       return GNUNET_OK;
-      lal = lal->next;
+    case AF_INET:
+      GNUNET_assert (addrlen == sizeof (struct sockaddr_in));
+      t4.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
+      t4.t4_port = ((struct sockaddr_in *) addr)->sin_port;
+      arg = &t4;
+      args = sizeof (t4);
+      break;
+    case AF_INET6:
+      GNUNET_assert (addrlen == sizeof (struct sockaddr_in6));
+      memcpy (&t6.ipv6_addr,
+             &((struct sockaddr_in6 *) addr)->sin6_addr,
+             sizeof (struct in6_addr));
+      t6.t6_port = ((struct sockaddr_in6 *) addr)->sin6_port;
+      arg = &t6;
+      args = sizeof (t6);    
+      break;
+    default:
+      GNUNET_break (0);
+      return;
     }
-  return GNUNET_SYSERR;
+  /* modify our published address list */
+  plugin->env->notify_address (plugin->env->cls,
+                              add_remove,
+                              arg, args);
 }
 
 
@@ -521,15 +504,16 @@ tcp_address_to_string (void *cls,
     {
       t4 = addr;
       af = AF_INET;
-      port = ntohs (t4->t_port);
+      port = ntohs (t4->t4_port);
       memcpy (&a4, &t4->ipv4_addr, sizeof (a4));
       sb = &a4;
     }
   else
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                 _("Unexpected address length: %u\n"),
-                 addrlen);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                      _("Unexpected address length: %u bytes\n"),
+                      (unsigned int) addrlen);
       GNUNET_break (0);
       return NULL;
     }
@@ -550,6 +534,8 @@ tcp_address_to_string (void *cls,
 /**
  * Find the session handle for the given client.
  *
+ * @param plugin the plugin
+ * @param client which client to find the session handle for
  * @return NULL if no matching session exists
  */
 static struct Session *
@@ -564,10 +550,11 @@ find_session_by_client (struct Plugin *plugin,
   return ret;
 }
 
+
 /**
  * Create a new session.  Also queues a welcome message.
  *
- * @param plugin us
+ * @param plugin the plugin
  * @param target peer to connect to
  * @param client client to use
  * @param is_nat this a NAT session, we should wait for a client to
@@ -578,7 +565,8 @@ find_session_by_client (struct Plugin *plugin,
 static struct Session *
 create_session (struct Plugin *plugin,
                 const struct GNUNET_PeerIdentity *target,
-                struct GNUNET_SERVER_Client *client, int is_nat)
+                struct GNUNET_SERVER_Client *client, 
+               int is_nat)
 {
   struct Session *ret;
   struct PendingMessage *pm;
@@ -588,9 +576,9 @@ create_session (struct Plugin *plugin,
     GNUNET_assert (client != NULL);
   else
     GNUNET_assert (client == NULL);
-
 #if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
                   "Creating new session for peer `%4s'\n",
                   GNUNET_i2s (target));
 #endif
@@ -663,12 +651,14 @@ do_transmit (void *cls, size_t size, void *buf)
   char *cbuf;
   size_t ret;
 
+  GNUNET_assert (session != NULL);
   session->transmit_handle = NULL;
   plugin = session->plugin;
   if (buf == NULL)
     {
 #if DEBUG_TCP
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
                        "Timeout trying to transmit to peer `%4s', discarding message queue.\n",
                        GNUNET_i2s (&session->target));
 #endif
@@ -678,13 +668,14 @@ do_transmit (void *cls, size_t size, void *buf)
       ret = 0;
       now = GNUNET_TIME_absolute_get ();
       while ( (NULL != (pos = session->pending_messages_head)) &&
-             (pos->timeout.value <= now.value) )
+             (pos->timeout.abs_value <= now.abs_value) )
        {
          GNUNET_CONTAINER_DLL_remove (session->pending_messages_head,
                                       session->pending_messages_tail,
                                       pos);
 #if DEBUG_TCP
-          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+          GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                          "tcp",
                            "Failed to transmit %u byte message to `%4s'.\n",
                           pos->message_size,
                            GNUNET_i2s (&session->target));
@@ -756,8 +747,10 @@ do_transmit (void *cls, size_t size, void *buf)
   GNUNET_assert (hd == NULL);
   GNUNET_assert (tl == NULL);
 #if DEBUG_TCP > 1
-  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
-             "Transmitting %u bytes\n", ret);
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  "Transmitting %u bytes\n", 
+                  ret);
 #endif
   GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# bytes currently in TCP buffers"),
@@ -812,14 +805,14 @@ disconnect_session (struct Session *session)
   struct PendingMessage *pm;
 
 #if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                   "Disconnecting from `%4s' at %s (session %p).\n",
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                   "Disconnecting from `%4s' at %s.\n",
                    GNUNET_i2s (&session->target),
                    (session->connect_addr != NULL) ?
                    tcp_address_to_string (session->plugin,
                                          session->connect_addr,
-                                         session->connect_alen) : "*",
-                  session);
+                                         session->connect_alen) : "*");
 #endif
   /* remove from session list */
   prev = NULL;
@@ -833,9 +826,7 @@ disconnect_session (struct Session *session)
     session->plugin->sessions = session->next;
   else
     prev->next = session->next;
-  session->plugin->env->session_end (session->plugin->env->cls,
-                                    &session->target,
-                                    session);
+
   /* clean up state */
   if (session->transmit_handle != NULL)
     {
@@ -846,12 +837,11 @@ disconnect_session (struct Session *session)
   while (NULL != (pm = session->pending_messages_head))
     {
 #if DEBUG_TCP
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
                        pm->transmit_cont != NULL
                        ? "Could not deliver message to `%4s'.\n"
-                       :
-                       "Could not deliver message to `%4s', notifying.\n",
+                       : "Could not deliver message to `%4s', notifying.\n",
                        GNUNET_i2s (&session->target));
 #endif
       GNUNET_STATISTICS_update (session->plugin->env->stats,
@@ -873,19 +863,25 @@ disconnect_session (struct Session *session)
   GNUNET_break (session->client != NULL);
   if (session->receive_delay_task != GNUNET_SCHEDULER_NO_TASK)
     {
-      GNUNET_SCHEDULER_cancel (session->plugin->env->sched,
-                              session->receive_delay_task);
+      GNUNET_SCHEDULER_cancel (session->receive_delay_task);
       if (session->client != NULL)
        GNUNET_SERVER_receive_done (session->client,
                                    GNUNET_SYSERR);     
     }
-  if (session->client != NULL) 
-    GNUNET_SERVER_client_drop (session->client);
+  if (session->client != NULL)
+    {
+      GNUNET_SERVER_client_drop (session->client);
+      session->client = NULL;
+    }
   GNUNET_STATISTICS_update (session->plugin->env->stats,
                            gettext_noop ("# TCP sessions active"),
                            -1,
                            GNUNET_NO);
   GNUNET_free_non_null (session->connect_addr);
+  session->plugin->env->session_end (session->plugin->env->cls,
+                                     &session->target,
+                                     session);
+  GNUNET_assert (NULL == session->transmit_handle);
   GNUNET_free (session);
 }
 
@@ -911,9 +907,9 @@ select_better_session (struct Session *s1,
   if ( (s1->expecting_welcome == GNUNET_YES) &&
        (s2->expecting_welcome == GNUNET_NO) )
     return s2;
-  if (s1->last_activity.value < s2->last_activity.value)
+  if (s1->last_activity.abs_value < s2->last_activity.abs_value)
     return s2;
-  if (s1->last_activity.value > s2->last_activity.value)
+  if (s1->last_activity.abs_value > s2->last_activity.abs_value)
     return s1;
   if ( (GNUNET_YES == s1->inbound) &&
        (GNUNET_NO  == s2->inbound) )
@@ -925,63 +921,6 @@ select_better_session (struct Session *s1,
 }
 
 
-/**
- * We learned about a peer (possibly behind NAT) so run the
- * gnunet-nat-client to send dummy ICMP responses
- *
- * @param plugin the plugin for this transport
- * @param addr the address of the peer
- * @param addrlen the length of the address
- */
-void
-run_gnunet_nat_client (struct Plugin *plugin, const char *addr, size_t addrlen)
-{
-  char inet4[INET_ADDRSTRLEN];
-  char *address_as_string;
-  char *port_as_string;
-  pid_t pid;
-  const struct sockaddr *sa = (const struct sockaddr *)addr;
-
-#if DEBUG_TCP_NAT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _("called run_gnunet_nat_client addrlen %d others are %d and %d\n"), addrlen, sizeof (struct sockaddr), sizeof (struct sockaddr_in));
-#endif
-
-  if (addrlen < sizeof (struct sockaddr))
-    return;
-
-  switch (sa->sa_family)
-    {
-    case AF_INET:
-      if (addrlen != sizeof (struct sockaddr_in))
-        return;
-      if (NULL == inet_ntop (AF_INET,
-                            &((struct sockaddr_in *) sa)->sin_addr,
-                            inet4, INET_ADDRSTRLEN))
-       {
-         GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "inet_ntop");
-         return;
-       }
-      address_as_string = GNUNET_strdup (inet4);
-      break;
-    case AF_INET6:
-    default:
-      return;
-    }
-
-  GNUNET_asprintf(&port_as_string, "%d", plugin->adv_port);
-#if DEBUG_TCP_NAT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _("Running gnunet-nat-client with arguments: %s %s %d\n"), plugin->external_address, address_as_string, plugin->adv_port);
-#endif
-
-  /* Start the client process */
-  pid = GNUNET_OS_start_process(NULL, NULL, "gnunet-nat-client", "gnunet-nat-client", plugin->external_address, address_as_string, port_as_string, NULL);
-  GNUNET_free(address_as_string);
-  GNUNET_free(port_as_string);
-  GNUNET_OS_process_wait (pid);
-}
-
 
 /**
  * Function that can be used by the transport service to transmit
@@ -1082,9 +1021,8 @@ tcp_plugin_send (void *cls,
              GNUNET_break (0);
              break;
            }
-         if (session->inbound == GNUNET_YES)
-           continue;
-         if ((addrlen != session->connect_alen) && (session->is_nat == GNUNET_NO))
+         if ( (addrlen != session->connect_alen) && 
+              (session->is_nat == GNUNET_NO) )
            continue;
          if ((0 != memcmp (session->connect_addr,
                           addr,
@@ -1099,8 +1037,9 @@ tcp_plugin_send (void *cls,
        (addr == NULL) )
     {
 #if DEBUG_TCP
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                       "Asked to transmit to `%4s' without address and I have no existing connection (failing).\n",
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                      "Asked to transmit to `%4s' without address and I have no existing connection (failing).\n",
                        GNUNET_i2s (target));
 #endif
       GNUNET_STATISTICS_update (plugin->env->stats,
@@ -1138,8 +1077,8 @@ tcp_plugin_send (void *cls,
           a4.sin_len = sizeof (a4);
 #endif
          a4.sin_family = AF_INET;
-         a4.sin_port = t4->t_port;
-         if (t4->t_port == 0)
+         a4.sin_port = t4->t4_port;
+         if (t4->t4_port == 0)
            is_natd = GNUNET_YES;
          a4.sin_addr.s_addr = t4->ipv4_addr;
          sb = &a4;
@@ -1147,7 +1086,8 @@ tcp_plugin_send (void *cls,
        }
       else
        {
-         GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+         GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                          "tcp",
                           _("Address of unexpected length: %u\n"),
                           addrlen);
          GNUNET_break (0);
@@ -1156,18 +1096,24 @@ tcp_plugin_send (void *cls,
 
       if ((is_natd == GNUNET_YES) && (addrlen == sizeof (struct IPv6TcpAddress)))
         return -1; /* NAT client only works with IPv4 addresses */
+      if (0 == plugin->max_connections)
+       return -1; /* saturated */
 
-
-      if ((plugin->allow_nat == GNUNET_YES) && (is_natd == GNUNET_YES) &&
-           (GNUNET_NO == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, &target->hashPubKey)))
+      if ( (is_natd == GNUNET_YES) &&
+          (NULL != plugin->nat) &&
+           (GNUNET_NO == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns,
+                                                               &target->hashPubKey)) )
         {
 #if DEBUG_TCP_NAT
-          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                           _("Found valid IPv4 NAT address!\n"));
+          GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                          "tcp",
+                           _("Found valid IPv4 NAT address (creating session)!\n"));
 #endif
           session = create_session (plugin,
                                     target,
-                                    NULL, is_natd);
+                                    NULL, 
+                                   GNUNET_YES);
+          GNUNET_assert (session != NULL);
 
           /* create new message entry */
           pm = GNUNET_malloc (sizeof (struct PendingMessage) + msgbuf_size);
@@ -1187,27 +1133,33 @@ tcp_plugin_send (void *cls,
                                              session->pending_messages_tail,
                                              pm);
 
-          GNUNET_assert(GNUNET_CONTAINER_multihashmap_put(plugin->nat_wait_conns, &target->hashPubKey, session, GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY) == GNUNET_OK);
+          GNUNET_assert(GNUNET_CONTAINER_multihashmap_put(plugin->nat_wait_conns,
+                                                         &target->hashPubKey,
+                                                         session, 
+                                                         GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY) == GNUNET_OK);
 #if DEBUG_TCP_NAT
-          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+          GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                          "tcp",
                            "Created NAT WAIT connection to `%4s' at `%s'\n",
                            GNUNET_i2s (target),
                            GNUNET_a2s (sb, sbs));
 #endif
-          run_gnunet_nat_client (plugin, sb, sbs);
+          GNUNET_NAT_run_client (plugin->nat, &a4);
           return 0;
         }
-      else if ((plugin->allow_nat == GNUNET_YES) && (is_natd == GNUNET_YES) && (GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, &target->hashPubKey)))
+      if ( (is_natd == GNUNET_YES) && 
+          (GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, 
+                                                                &target->hashPubKey)) )
         {
           /* Only do one NAT punch attempt per peer identity */
           return -1;
         }
-      sa = GNUNET_CONNECTION_create_from_sockaddr (plugin->env->sched,
-                                                  af, sb, sbs);
+      sa = GNUNET_CONNECTION_create_from_sockaddr (af, sb, sbs);
       if (sa == NULL)
        {
 #if DEBUG_TCP
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+         GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                          "tcp",
                           "Failed to create connection to `%4s' at `%s'\n",
                           GNUNET_i2s (target),
                           GNUNET_a2s (sb, sbs));
@@ -1218,8 +1170,11 @@ tcp_plugin_send (void *cls,
                                    GNUNET_NO);
          return -1;
        }
-#if DEBUG_TCP
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+      GNUNET_assert (0 != plugin->max_connections);
+      plugin->max_connections--;
+#if DEBUG_TCP_NAT
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
                        "Asked to transmit to `%4s', creating fresh session using address `%s'.\n",
                       GNUNET_i2s (target),
                       GNUNET_a2s (sb, sbs));
@@ -1227,15 +1182,31 @@ tcp_plugin_send (void *cls,
       session = create_session (plugin,
                                target,
                                GNUNET_SERVER_connect_socket (plugin->server,
-                                                             sa), is_natd);
+                                                             sa), 
+                               GNUNET_NO);
       session->connect_addr = GNUNET_malloc (addrlen);
       memcpy (session->connect_addr,
              addr,
              addrlen);
       session->connect_alen = addrlen;
     }
+  else  /* session != NULL */
+    {
+      /* check if session is valid */
+      struct Session * ses = plugin->sessions;
+      while ((ses != NULL) && (ses != session))
+        ses = ses->next;
+      if (ses == NULL)
+       {
+         GNUNET_break (0);
+         return -1;
+       }
+    }
   GNUNET_assert (session != NULL);
   GNUNET_assert (session->client != NULL);
+
+
+  GNUNET_SERVER_client_set_timeout(session->client, GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
   GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# bytes currently in TCP buffers"),
                            msgbuf_size,
@@ -1255,7 +1226,8 @@ tcp_plugin_send (void *cls,
                                     session->pending_messages_tail,
                                     pm);
 #if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
                   "Asked to transmit %u bytes to `%s', added message to list.\n",
                   msgbuf_size,
                   GNUNET_i2s (target));
@@ -1291,7 +1263,8 @@ tcp_plugin_disconnect (void *cls,
   struct PendingMessage *pm;
 
 #if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
                    "Asked to cancel session with `%4s'\n",
                    GNUNET_i2s (target));
 #endif
@@ -1310,6 +1283,10 @@ tcp_plugin_disconnect (void *cls,
          pm->transmit_cont_cls = NULL;
          pm = pm->next;
        }
+      GNUNET_STATISTICS_update (session->plugin->env->stats,
+                               gettext_noop ("# transport-service disconnect requests for TCP"),
+                               1,
+                               GNUNET_NO);
       disconnect_session (session);
     }
 }
@@ -1385,7 +1362,6 @@ tcp_plugin_address_pretty_printer (void *cls,
                                    GNUNET_TRANSPORT_AddressStringCallback asc,
                                    void *asc_cls)
 {
-  struct Plugin *plugin = cls;
   struct PrettyPrinterContext *ppc;
   const void *sb;
   size_t sbs;
@@ -1413,9 +1389,9 @@ tcp_plugin_address_pretty_printer (void *cls,
       t4 = addr;
       memset (&a4, 0, sizeof (a4));
       a4.sin_family = AF_INET;
-      a4.sin_port = t4->t_port;
+      a4.sin_port = t4->t4_port;
       a4.sin_addr.s_addr = t4->ipv4_addr;
-      port = ntohs (t4->t_port);
+      port = ntohs (t4->t4_port);
       sb = &a4;
       sbs = sizeof (a4);
     }
@@ -1430,33 +1406,26 @@ tcp_plugin_address_pretty_printer (void *cls,
   ppc->asc = asc;
   ppc->asc_cls = asc_cls;
   ppc->port = port;
-  GNUNET_RESOLVER_hostname_get (plugin->env->sched,
-                                plugin->env->cfg,
-                                sb,
+  GNUNET_RESOLVER_hostname_get (sb,
                                 sbs,
                                 !numeric, timeout, &append_port, ppc);
 }
 
 
 /**
- * Check if the given port is plausible (must be either
- * our listen port or our advertised port).  If it is
- * neither, we return GNUNET_SYSERR.
+ * Check if the given port is plausible (must be either our listen
+ * port or our advertised port), or any port if we are behind NAT
+ * and do not have a port open.  If it is neither, we return
+ * GNUNET_SYSERR.
  *
  * @param plugin global variables
  * @param in_port port number to check
  * @return GNUNET_OK if port is either open_port or adv_port
  */
 static int
-check_port (struct Plugin *plugin, uint16_t in_port)
+check_port (struct Plugin *plugin, 
+           uint16_t in_port)
 {
-  if ( (plugin->behind_nat == GNUNET_YES) && (in_port == 0) )
-    return GNUNET_OK;
-  if ( (plugin->only_nat_addresses == GNUNET_YES) &&
-       (plugin->behind_nat == GNUNET_YES) )
-    {
-      return GNUNET_SYSERR; /* odd case... */
-    }
   if ((in_port == plugin->adv_port) || (in_port == plugin->open_port))
     return GNUNET_OK;
   return GNUNET_SYSERR;
@@ -1497,13 +1466,12 @@ tcp_plugin_check_address (void *cls,
     {
       v4 = (struct IPv4TcpAddress *) addr;
       if (GNUNET_OK !=
-         check_port (plugin, ntohs (v4->t_port)))
+         check_port (plugin, ntohs (v4->t4_port)))
        return GNUNET_SYSERR;
       if (GNUNET_OK !=
-         check_local_addr (plugin, &v4->ipv4_addr, sizeof (uint32_t)))
-       {
-         return GNUNET_SYSERR;
-       }
+         GNUNET_NAT_test_address (plugin->nat,
+                                  &v4->ipv4_addr, sizeof (struct in_addr)))
+       return GNUNET_SYSERR;   
     }
   else
     {
@@ -1517,14 +1485,14 @@ tcp_plugin_check_address (void *cls,
          check_port (plugin, ntohs (v6->t6_port)))
        return GNUNET_SYSERR;
       if (GNUNET_OK !=
-         check_local_addr (plugin, &v6->ipv6_addr, sizeof (struct in6_addr)))
-       {
-         return GNUNET_SYSERR;
-       }
+         GNUNET_NAT_test_address (plugin->nat,
+                                  &v6->ipv6_addr, sizeof (struct in6_addr)))
+       return GNUNET_SYSERR;
     }
   return GNUNET_OK;
 }
 
+
 /**
  * We've received a nat probe from this peer via TCP.  Finish
  * creating the client session and resume sending of queued
@@ -1536,12 +1504,12 @@ tcp_plugin_check_address (void *cls,
  */
 static void
 handle_tcp_nat_probe (void *cls,
-                     struct GNUNET_SERVER_Client *client,
-                     const struct GNUNET_MessageHeader *message)
+                     struct GNUNET_SERVER_Client *client,
+                     const struct GNUNET_MessageHeader *message)
 {
   struct Plugin *plugin = cls;
   struct Session *session;
-  struct TCP_NAT_ProbeMessage *tcp_nat_probe;
+  const struct TCP_NAT_ProbeMessage *tcp_nat_probe;
   size_t alen;
   void *vaddr;
   struct IPv4TcpAddress *t4;
@@ -1550,7 +1518,9 @@ handle_tcp_nat_probe (void *cls,
   const struct sockaddr_in6 *s6;
 
 #if DEBUG_TCP_NAT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "received tcp NAT probe\n");
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                  "tcp",
+                  "received NAT probe\n");
 #endif
   /* We have received a TCP NAT probe, meaning we (hopefully) initiated
    * a connection to this peer by running gnunet-nat-client.  This peer
@@ -1560,84 +1530,107 @@ handle_tcp_nat_probe (void *cls,
    */
   if (ntohs(message->size) != sizeof(struct TCP_NAT_ProbeMessage))
     {
-#if DEBUG_TCP_NAT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Bad size for tcp NAT probe, expected %d got %d.\n", sizeof(struct TCP_NAT_ProbeMessage), ntohs(message->size));
-#endif
       GNUNET_break_op(0);
+      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
       return;
     }
-  tcp_nat_probe = (struct TCP_NAT_ProbeMessage *)message;
 
-  if (GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, &tcp_nat_probe->clientIdentity.hashPubKey) == GNUNET_YES)
+  tcp_nat_probe = (const struct TCP_NAT_ProbeMessage *)message;
+  if (0 == memcmp (&tcp_nat_probe->clientIdentity,
+                   plugin->env->my_identity,
+                   sizeof (struct GNUNET_PeerIdentity)))
     {
-#if DEBUG_TCP_NAT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Found session for NAT probe!\n");
-#endif
-      session = GNUNET_CONTAINER_multihashmap_get(plugin->nat_wait_conns, &tcp_nat_probe->clientIdentity.hashPubKey);
-      GNUNET_assert(session != NULL);
-      GNUNET_assert(GNUNET_CONTAINER_multihashmap_remove(plugin->nat_wait_conns, &tcp_nat_probe->clientIdentity.hashPubKey, session) == GNUNET_YES);
-      GNUNET_SERVER_client_keep (client);
-      session->client = client;
-      session->last_activity = GNUNET_TIME_absolute_get ();
-      session->inbound = GNUNET_NO;
+      /* refuse connections from ourselves */
+      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
+      return;
+    }
 
-      if (GNUNET_OK ==
-          GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
-        {
+  session = GNUNET_CONTAINER_multihashmap_get(plugin->nat_wait_conns, 
+                                             &tcp_nat_probe->clientIdentity.hashPubKey);
+  if (session == NULL)
+    {
 #if DEBUG_TCP_NAT
-          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                           "Found address `%s' for incoming connection %p\n",
-                           GNUNET_a2s (vaddr, alen),
-                           client);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                      "Did NOT find session for NAT probe!\n");
 #endif
-          if (((const struct sockaddr *)vaddr)->sa_family == AF_INET)
-            {
-              s4 = vaddr;
-              t4 = GNUNET_malloc (sizeof (struct IPv4TcpAddress));
-              t4->t_port = s4->sin_port;
-              t4->ipv4_addr = s4->sin_addr.s_addr;
-              session->connect_addr = t4;
-              session->connect_alen = sizeof (struct IPv4TcpAddress);
-            }
-          else if (((const struct sockaddr *)vaddr)->sa_family == AF_INET6)
-            {
-              s6 = vaddr;
-              t6 = GNUNET_malloc (sizeof (struct IPv6TcpAddress));
-              t6->t6_port = s6->sin6_port;
-              memcpy (&t6->ipv6_addr,
-                      &s6->sin6_addr,
-                      sizeof (struct in6_addr));
-              session->connect_addr = t6;
-              session->connect_alen = sizeof (struct IPv6TcpAddress);
-            }
-          else
-            {
+      GNUNET_SERVER_receive_done (client, GNUNET_OK);
+      return;
+    }
 #if DEBUG_TCP_NAT
-              GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                          "Bad address for incoming connection!\n");
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                  "tcp",
+                  "Found session for NAT probe!\n");
 #endif
-            }
-          GNUNET_free (vaddr);
-        }
-
-      session->next = plugin->sessions;
-      plugin->sessions = session;
-      GNUNET_STATISTICS_update (plugin->env->stats,
-                                gettext_noop ("# TCP sessions active"),
-                                1,
-                                GNUNET_NO);
-      process_pending_messages (session);
+  GNUNET_assert(GNUNET_CONTAINER_multihashmap_remove(plugin->nat_wait_conns, 
+                                                    &tcp_nat_probe->clientIdentity.hashPubKey,
+                                                    session) == GNUNET_YES);
+  if (GNUNET_OK !=
+      GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
+    {
+      GNUNET_break (0);
+      GNUNET_free (session);
+      GNUNET_SERVER_receive_done (client, GNUNET_OK);
+      return;
     }
-  else
+
+  GNUNET_SERVER_client_keep (client);
+  session->client = client;
+  session->last_activity = GNUNET_TIME_absolute_get ();
+  session->inbound = GNUNET_NO;
+
+#if DEBUG_TCP_NAT
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  "Found address `%s' for incoming connection\n",
+                  GNUNET_a2s (vaddr, alen));
+#endif
+  switch (((const struct sockaddr *)vaddr)->sa_family)
     {
+    case AF_INET:
+      s4 = vaddr;
+      t4 = GNUNET_malloc (sizeof (struct IPv4TcpAddress));
+      t4->t4_port = s4->sin_port;
+      t4->ipv4_addr = s4->sin_addr.s_addr;
+      session->connect_addr = t4;
+      session->connect_alen = sizeof (struct IPv4TcpAddress);
+      break;
+    case AF_INET6:    
+      s6 = vaddr;
+      t6 = GNUNET_malloc (sizeof (struct IPv6TcpAddress));
+      t6->t6_port = s6->sin6_port;
+      memcpy (&t6->ipv6_addr,
+             &s6->sin6_addr,
+             sizeof (struct in6_addr));
+      session->connect_addr = t6;
+      session->connect_alen = sizeof (struct IPv6TcpAddress);
+      break;
+    default:
+      GNUNET_break_op (0);
 #if DEBUG_TCP_NAT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Did NOT find session for NAT probe!\n");
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                      "Bad address for incoming connection!\n");
 #endif
+      GNUNET_free (vaddr);
+      GNUNET_SERVER_client_drop (client);
+      GNUNET_free (session);
+      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
+      return;
     }
-
+  GNUNET_free (vaddr);
+  
+  session->next = plugin->sessions;
+  plugin->sessions = session;
+  GNUNET_STATISTICS_update (plugin->env->stats,
+                           gettext_noop ("# TCP sessions active"),
+                           1,
+                           GNUNET_NO);
+  process_pending_messages (session);
   GNUNET_SERVER_receive_done (client, GNUNET_OK);
 }
 
+
 /**
  * We've received a welcome from this peer via TCP.  Possibly create a
  * fresh client record and send back our welcome.
@@ -1660,38 +1653,57 @@ handle_tcp_welcome (void *cls,
   struct IPv6TcpAddress *t6;
   const struct sockaddr_in *s4;
   const struct sockaddr_in6 *s6;
-
+  
+  if (0 == memcmp (&wm->clientIdentity,
+                  plugin->env->my_identity,
+                  sizeof (struct GNUNET_PeerIdentity)))
+    {
+      /* refuse connections from ourselves */
+      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
+      return;
+    }
 #if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                   "Received %s message from a `%4s/%p'.\n",
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                   "Received %s message from `%4s'.\n",
                   "WELCOME",
-                   GNUNET_i2s (&wm->clientIdentity), client);
+                   GNUNET_i2s (&wm->clientIdentity));
 #endif
   GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# TCP WELCOME messages received"),
                            1,
                            GNUNET_NO);
   session = find_session_by_client (plugin, client);
+
   if (session == NULL)
     {
+#if DEBUG_TCP_NAT
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                       "Received %s message from a `%4s', creating new session\n",
+                       "WELCOME",
+                       GNUNET_i2s (&wm->clientIdentity));
+#endif
       GNUNET_SERVER_client_keep (client);
       session = create_session (plugin,
-                               &wm->clientIdentity, client, GNUNET_NO);
+                               &wm->clientIdentity,
+                               client,
+                               GNUNET_NO);
       session->inbound = GNUNET_YES;
       if (GNUNET_OK ==
          GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
        {
-#if DEBUG_TCP
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                          "Found address `%s' for incoming connection %p\n",
-                          GNUNET_a2s (vaddr, alen),
-                          client);
+#if DEBUG_TCP_NAT
+         GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                          "tcp",
+                          "Found address `%s' for incoming connection\n",
+                          GNUNET_a2s (vaddr, alen));
 #endif
          if (alen == sizeof (struct sockaddr_in))
            {
              s4 = vaddr;
              t4 = GNUNET_malloc (sizeof (struct IPv4TcpAddress));
-             t4->t_port = s4->sin_port;
+             t4->t4_port = s4->sin_port;
              t4->ipv4_addr = s4->sin_addr.s_addr;
              session->connect_addr = t4;
              session->connect_alen = sizeof (struct IPv4TcpAddress);
@@ -1707,22 +1719,34 @@ handle_tcp_welcome (void *cls,
              session->connect_addr = t6;
              session->connect_alen = sizeof (struct IPv6TcpAddress);
            }
+
          GNUNET_free (vaddr);
        }
       else
         {
 #if DEBUG_TCP
-         GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+         GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                          "tcp",
                           "Did not obtain TCP socket address for incoming connection\n");
 #endif
         }
-#if DEBUG_TCP
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                       "Creating new session %p for connection %p\n",
-                       session, client);
-#endif
       process_pending_messages (session);
     }
+  else
+    {
+#if DEBUG_TCP_NAT
+    if (GNUNET_OK ==
+        GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
+      {
+        GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                        "tcp",
+                        "Found address `%s' (already have session)\n",
+                        GNUNET_a2s (vaddr, alen));
+       GNUNET_free (vaddr);
+      }
+#endif
+    }
+
   if (session->expecting_welcome != GNUNET_YES)
     {
       GNUNET_break_op (0);
@@ -1731,6 +1755,7 @@ handle_tcp_welcome (void *cls,
     }
   session->last_activity = GNUNET_TIME_absolute_get ();
   session->expecting_welcome = GNUNET_NO;
+  GNUNET_SERVER_client_set_timeout(client, GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
   GNUNET_SERVER_receive_done (client, GNUNET_OK);
 }
 
@@ -1743,7 +1768,8 @@ handle_tcp_welcome (void *cls,
  * @param tc task context (unused)
  */
 static void
-delayed_done (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+delayed_done (void *cls, 
+             const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
   struct Session *session = cls;
   struct GNUNET_TIME_Relative delay;
@@ -1751,15 +1777,15 @@ delayed_done (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
   session->receive_delay_task = GNUNET_SCHEDULER_NO_TASK;
   delay = session->plugin->env->receive (session->plugin->env->cls,
                                         &session->target,
+                                        NULL,
                                         NULL, 0,
                                         session,
                                         NULL, 0);
-  if (delay.value == 0)
+  if (delay.rel_value == 0)
     GNUNET_SERVER_receive_done (session->client, GNUNET_OK);
   else
     session->receive_delay_task =
-      GNUNET_SCHEDULER_add_delayed (session->plugin->env->sched,
-                                   delay, &delayed_done, session);
+      GNUNET_SCHEDULER_add_delayed (delay, &delayed_done, session);
 }
 
 
@@ -1779,22 +1805,26 @@ handle_tcp_data (void *cls,
   struct Plugin *plugin = cls;
   struct Session *session;
   struct GNUNET_TIME_Relative delay;
+  uint16_t type;
 
-  if ((GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME == ntohs(message->type)) || (ntohs(message->type) == GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE))
+  type = ntohs (message->type);
+  if ( (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME == type) || 
+       (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE == type) )
     {
       /* We don't want to propagate WELCOME and NAT Probe messages up! */
       GNUNET_SERVER_receive_done (client, GNUNET_OK);
       return;
     }
   session = find_session_by_client (plugin, client);
-  if ( (NULL == session) || (GNUNET_YES == session->expecting_welcome))
+  if ( (NULL == session) || (GNUNET_YES == session->expecting_welcome) )
     {
       GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
       return;
     }
   session->last_activity = GNUNET_TIME_absolute_get ();
-#if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+#if DEBUG_TCP > 1
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
                   "Passing %u bytes of type %u from `%4s' to transport service.\n",
                    (unsigned int) ntohs (message->size),
                   (unsigned int) ntohs (message->type),
@@ -1804,16 +1834,34 @@ handle_tcp_data (void *cls,
                            gettext_noop ("# bytes received via TCP"),
                            ntohs (message->size),
                            GNUNET_NO);
-  delay = plugin->env->receive (plugin->env->cls, &session->target, message, 1,
+  struct GNUNET_TRANSPORT_ATS_Information distance[2];
+  distance[0].type = htonl (GNUNET_TRANSPORT_ATS_QUALITY_NET_DISTANCE);
+  distance[0].value = htonl (1);
+  distance[1].type = htonl (GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR);
+  distance[1].value = htonl (0);
+  delay = plugin->env->receive (plugin->env->cls, &session->target, message,
+                               (const struct GNUNET_TRANSPORT_ATS_Information *) &distance,
+                               2,
                                session,
                                (GNUNET_YES == session->inbound) ? NULL : session->connect_addr,
                                (GNUNET_YES == session->inbound) ? 0 : session->connect_alen);
-  if (delay.value == 0)
-    GNUNET_SERVER_receive_done (client, GNUNET_OK);
+  if (delay.rel_value == 0)
+    {
+      GNUNET_SERVER_receive_done (client, GNUNET_OK);
+    }
   else
-    session->receive_delay_task =
-      GNUNET_SCHEDULER_add_delayed (session->plugin->env->sched,
-                                   delay, &delayed_done, session);
+    {
+#if DEBUG_TCP 
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                      "Throttling receiving from `%s' for %llu ms\n",
+                      GNUNET_i2s (&session->target),
+                      (unsigned long long) delay.rel_value);
+#endif
+      GNUNET_SERVER_disable_receive_done_warning (client);
+      session->receive_delay_task =
+       GNUNET_SCHEDULER_add_delayed (delay, &delayed_done, session);
+    }
 }
 
 
@@ -1833,413 +1881,120 @@ disconnect_notify (void *cls,
 
   if (client == NULL)
     return;
+  plugin->max_connections++;
   session = find_session_by_client (plugin, client);
   if (session == NULL)
     return;                     /* unknown, nothing to do */
 #if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                   "Destroying session of `%4s' with %s (%p) due to network-level disconnect.\n",
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                   "Destroying session of `%4s' with %s due to network-level disconnect.\n",
                    GNUNET_i2s (&session->target),
                    (session->connect_addr != NULL) ?
                    tcp_address_to_string (session->plugin,
                                          session->connect_addr,
-                                         session->connect_alen) : "*",
-                  client);
+                                         session->connect_alen) : "*");
 #endif
+  GNUNET_STATISTICS_update (session->plugin->env->stats,
+                           gettext_noop ("# network-level TCP disconnect events"),
+                           1,
+                           GNUNET_NO);
   disconnect_session (session);
 }
 
 
-/**
- * Add the IP of our network interface to the list of
- * our external IP addresses.
- *
- * @param cls the 'struct Plugin*'
- * @param name name of the interface
- * @param isDefault do we think this may be our default interface
- * @param addr address of the interface
- * @param addrlen number of bytes in addr
- * @return GNUNET_OK to continue iterating
- */
-static int
-process_interfaces (void *cls,
-                    const char *name,
-                    int isDefault,
-                    const struct sockaddr *addr, socklen_t addrlen)
-{
-  struct Plugin *plugin = cls;
-  int af;
-  struct IPv4TcpAddress t4;
-  struct IPv6TcpAddress t6;
-  struct IPv4TcpAddress t4_nat;
-  struct IPv6TcpAddress t6_nat;
-  void *arg;
-  uint16_t args;
-  void *arg_nat;
-  char buf[INET_ADDRSTRLEN];
-
-  af = addr->sa_family;
-  arg_nat = NULL;
-  if (af == AF_INET)
-    {
-      t4.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
-      GNUNET_assert(NULL != inet_ntop(AF_INET, &t4.ipv4_addr, &buf[0], INET_ADDRSTRLEN));
-      if ((plugin->bind_address != NULL) && (0 != strcmp(buf, plugin->bind_address)))
-        {
-          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "%s: Not notifying transport of address %s\n", "TCP", GNUNET_a2s (addr, addrlen));
-          return GNUNET_OK;
-        }
-      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (uint32_t));
-      if ((plugin->behind_nat == GNUNET_YES) && (plugin->only_nat_addresses == GNUNET_YES))
-        t4.t_port = htons(0);
-      else if (plugin->behind_nat == GNUNET_YES) /* We are behind NAT, but will advertise NAT and normal addresses */
-        {
-          t4_nat.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
-          t4_nat.t_port = htons(plugin->adv_port);
-          arg_nat = &t4_nat;
-        }
-      else
-        t4.t_port = htons (plugin->adv_port);
-      arg = &t4;
-      args = sizeof (t4);
-    }
-  else if (af == AF_INET6)
-    {
-      if ((IN6_IS_ADDR_LINKLOCAL (&((struct sockaddr_in6 *) addr)->sin6_addr)) || (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno(plugin->env->cfg, "transport-tcp", "disablev6")))
-       {
-         /* skip link local addresses */
-         return GNUNET_OK;
-       }
-      memcpy (&t6.ipv6_addr,
-             &((struct sockaddr_in6 *) addr)->sin6_addr,
-             sizeof (struct in6_addr));
-      add_to_address_list (plugin, &t6.ipv6_addr, sizeof (struct in6_addr));
-      if ((plugin->behind_nat == GNUNET_YES) && (plugin->only_nat_addresses == GNUNET_YES))
-        t6.t6_port = htons(0);
-      else if (plugin->behind_nat == GNUNET_YES) /* We are behind NAT, but will advertise NAT and normal addresses */
-        {
-          memcpy (&t6_nat.ipv6_addr,
-                  &((struct sockaddr_in6 *) addr)->sin6_addr,
-                  sizeof (struct in6_addr));
-          t6_nat.t6_port = htons(plugin->adv_port);
-          arg_nat = &t6;
-        }
-      else
-        t6.t6_port = htons (plugin->adv_port);
-      arg = &t6;
-      args = sizeof (t6);
-    }
-  else
-    {
-      GNUNET_break (0);
-      return GNUNET_OK;
-    }
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _("Found address `%s' (%s) len %d\n"),
-                   GNUNET_a2s (addr, addrlen), name, args);
-
-  plugin->env->notify_address (plugin->env->cls,
-                               "tcp",
-                               arg, args, GNUNET_TIME_UNIT_FOREVER_REL);
-
-  if (arg_nat != NULL)
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                      _("Found address `%s' (%s) len %d\n"),
-                      GNUNET_a2s (addr, addrlen), name, args);
-      plugin->env->notify_address (plugin->env->cls,
-                                   "tcp",
-                                   arg_nat, args, GNUNET_TIME_UNIT_FOREVER_REL);
-    }
-
-  return GNUNET_OK;
-}
-
-
-/**
- * Function called by the resolver for each address obtained from DNS
- * for our own hostname.  Add the addresses to the list of our
- * external IP addresses.
- *
- * @param cls closure
- * @param addr one of the addresses of the host, NULL for the last address
- * @param addrlen length of the address
- */
-static void
-process_hostname_ips (void *cls,
-                      const struct sockaddr *addr, socklen_t addrlen)
-{
-  struct Plugin *plugin = cls;
-
-  if (addr == NULL)
-    {
-      plugin->hostname_dns = NULL;
-      return;
-    }
-  /* FIXME: Can we figure out our external address here so it doesn't need to be user specified? */
-  process_interfaces (plugin, "<hostname>", GNUNET_YES, addr, addrlen);
-}
-
 /**
  * We can now send a probe message, copy into buffer to really send.
  *
  * @param cls closure, a struct TCPProbeContext
  * @param size max size to copy
  * @param buf buffer to copy message to
+ * @return number of bytes copied into buf
  */
-static size_t notify_send_probe (void *cls,
-                                 size_t size, void *buf)
+static size_t
+notify_send_probe (void *cls,
+                  size_t size,
+                  void *buf)
 {
   struct TCPProbeContext *tcp_probe_ctx = cls;
+  struct Plugin *plugin = tcp_probe_ctx->plugin;
+  size_t ret;
 
+  tcp_probe_ctx->transmit_handle = NULL;
+  GNUNET_CONTAINER_DLL_remove (plugin->probe_head,
+                              plugin->probe_tail,
+                              tcp_probe_ctx);
   if (buf == NULL)
     {
-      return 0;
+      GNUNET_CONNECTION_destroy (tcp_probe_ctx->sock, GNUNET_NO);
+      GNUNET_free(tcp_probe_ctx);
+      return 0;    
     }
-
   GNUNET_assert(size >= sizeof(tcp_probe_ctx->message));
   memcpy(buf, &tcp_probe_ctx->message, sizeof(tcp_probe_ctx->message));
   GNUNET_SERVER_connect_socket (tcp_probe_ctx->plugin->server,
                                 tcp_probe_ctx->sock);
-
+  ret = sizeof(tcp_probe_ctx->message);
   GNUNET_free(tcp_probe_ctx);
-  return sizeof(tcp_probe_ctx->message);
+  return ret;
 }
 
-/*
- * @param cls the plugin handle
- * @param tc the scheduling context (for rescheduling this function again)
- *
- * We have been notified that gnunet-nat-server has written something to stdout.
- * Handle the output, then reschedule this function to be called again once
- * more is available.
+
+/**
+ * Function called by the NAT subsystem suggesting another peer wants
+ * to connect to us via connection reversal.  Try to connect back to the
+ * given IP.
  *
+ * @param cls closure
+ * @param addr address to try
+ * @param addrlen number of bytes in addr
  */
 static void
-tcp_plugin_server_read (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+try_connection_reversal (void *cls,
+                        const struct sockaddr *addr,
+                        socklen_t addrlen)
 {
   struct Plugin *plugin = cls;
-  char mybuf[40];
-  ssize_t bytes;
-  memset(&mybuf, 0, sizeof(mybuf));
-  int i;
-  int port;
-  char *port_start;
-  struct sockaddr_in in_addr;
-  struct TCPProbeContext *tcp_probe_ctx;
   struct GNUNET_CONNECTION_Handle *sock;
+  struct TCPProbeContext *tcp_probe_ctx;
 
-  if (tc->reason == GNUNET_SCHEDULER_REASON_SHUTDOWN)
-    return;
-
-  bytes = GNUNET_DISK_file_read(plugin->server_stdout_handle, &mybuf, sizeof(mybuf));
-
-  if (bytes < 1)
-    {
-#if DEBUG_TCP_NAT
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                      _("Finished reading from server stdout with code: %d\n"), bytes);
-#endif
-      return;
-    }
-
-  port_start = NULL;
-  for (i = 0; i < sizeof(mybuf); i++)
-    {
-      if (mybuf[i] == '\n')
-        mybuf[i] = '\0';
-
-      if ((mybuf[i] == ':') && (i + 1 < sizeof(mybuf)))
-        {
-          mybuf[i] = '\0';
-          port_start = &mybuf[i + 1];
-        }
-    }
-
-  if (port_start != NULL)
-    port = atoi(port_start);
-  else
-    {
-      plugin->server_read_task =
-           GNUNET_SCHEDULER_add_read_file (plugin->env->sched,
-                                           GNUNET_TIME_UNIT_FOREVER_REL,
-                                           plugin->server_stdout_handle, &tcp_plugin_server_read, plugin);
-      return;
-    }
-
-#if DEBUG_TCP_NAT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _("nat-server-read read: %s port %d\n"), &mybuf, port);
-#endif
-
-
-  if (inet_pton(AF_INET, &mybuf[0], &in_addr.sin_addr) != 1)
-    {
-
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                  _("nat-server-read malformed address\n"), &mybuf, port);
-
-      plugin->server_read_task =
-          GNUNET_SCHEDULER_add_read_file (plugin->env->sched,
-                                          GNUNET_TIME_UNIT_FOREVER_REL,
-                                          plugin->server_stdout_handle, &tcp_plugin_server_read, plugin);
-      return;
-    }
-
-  in_addr.sin_family = AF_INET;
-  in_addr.sin_port = htons(port);
   /**
-   * We have received an ICMP response, ostensibly from a non-NAT'd peer
-   *  that wants to connect to us! Send a message to establish a connection.
+   * We have received an ICMP response, ostensibly from a peer
+   * that wants to connect to us! Send a message to establish a connection.
    */
-  sock = GNUNET_CONNECTION_create_from_sockaddr (plugin->env->sched, AF_INET, (struct sockaddr *)&in_addr,
-                                                 sizeof(in_addr));
-
-
+  sock = GNUNET_CONNECTION_create_from_sockaddr (AF_INET, 
+                                                addr,
+                                                addrlen);
   if (sock == NULL)
     {
-      plugin->server_read_task =
-          GNUNET_SCHEDULER_add_read_file (plugin->env->sched,
-                                          GNUNET_TIME_UNIT_FOREVER_REL,
-                                          plugin->server_stdout_handle, &tcp_plugin_server_read, plugin);
+      /* failed for some odd reason (out of sockets?); ignore attempt */
       return;
     }
-  else
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                _("Sending TCP probe message!\n"), &mybuf, port);
-
-      tcp_probe_ctx = GNUNET_malloc(sizeof(struct TCPProbeContext));
-      tcp_probe_ctx->message.header.size = htons(sizeof(struct TCP_NAT_ProbeMessage));
-      tcp_probe_ctx->message.header.type = htons(GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE);
-      memcpy(&tcp_probe_ctx->message.clientIdentity, plugin->env->my_identity, sizeof(struct GNUNET_PeerIdentity));
-      tcp_probe_ctx->plugin = plugin;
-      tcp_probe_ctx->sock = sock;
-      tcp_probe_ctx->transmit_handle = GNUNET_CONNECTION_notify_transmit_ready (sock,
-                                                                 ntohs(tcp_probe_ctx->message.header.size),
-                                                                 GNUNET_TIME_UNIT_FOREVER_REL,
-                                                                 &notify_send_probe, tcp_probe_ctx);
-
-    }
-
-  /*GNUNET_SERVER_connect_socket(plugin->server, sock);*/
-  plugin->server_read_task =
-      GNUNET_SCHEDULER_add_read_file (plugin->env->sched,
-                                      GNUNET_TIME_UNIT_FOREVER_REL,
-                                      plugin->server_stdout_handle, &tcp_plugin_server_read, plugin);
-}
-
-/**
- * Start the gnunet-nat-server process for users behind NAT.
- *
- * @param plugin the transport plugin
- *
- * @return GNUNET_YES if process was started, GNUNET_SYSERR on error
- */
-static int
-tcp_transport_start_nat_server(struct Plugin *plugin)
-{
-
-  plugin->server_stdout = GNUNET_DISK_pipe(GNUNET_YES);
-  if (plugin->server_stdout == NULL)
-    return GNUNET_SYSERR;
-
-#if DEBUG_TCP_NAT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                   "Starting gnunet-nat-server process cmd: %s %s\n", "gnunet-nat-server", plugin->internal_address);
-#endif
-  /* Start the server process */
-  plugin->server_pid = GNUNET_OS_start_process(NULL, plugin->server_stdout, "gnunet-nat-server", "gnunet-nat-server", plugin->internal_address, NULL);
-  if (plugin->server_pid == GNUNET_SYSERR)
-    {
-#if DEBUG_TCP_NAT
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Failed to start gnunet-nat-server process\n");
-#endif
-      return GNUNET_SYSERR;
-    }
-  /* Close the write end of the read pipe */
-  GNUNET_DISK_pipe_close_end(plugin->server_stdout, GNUNET_DISK_PIPE_END_WRITE);
-
-  plugin->server_stdout_handle = GNUNET_DISK_pipe_handle(plugin->server_stdout, GNUNET_DISK_PIPE_END_READ);
-  plugin->server_read_task =
-      GNUNET_SCHEDULER_add_read_file (plugin->env->sched,
-                                      GNUNET_TIME_UNIT_FOREVER_REL,
-                                      plugin->server_stdout_handle, &tcp_plugin_server_read, plugin);
-  return GNUNET_YES;
-}
 
-/**
- * Return the actual path to a file found in the current
- * PATH environment variable.
- *
- * @param binary the name of the file to find
- */
-static char *
-get_path_from_PATH (char *binary)
-{
-  char *path;
-  char *pos;
-  char *end;
-  char *buf;
-  const char *p;
-
-  p = getenv ("PATH");
-  if (p == NULL)
-    return NULL;
-  path = GNUNET_strdup (p);     /* because we write on it */
-  buf = GNUNET_malloc (strlen (path) + 20);
-  pos = path;
-
-  while (NULL != (end = strchr (pos, ':')))
-    {
-      *end = '\0';
-      sprintf (buf, "%s/%s", pos, binary);
-      if (GNUNET_DISK_file_test (buf) == GNUNET_YES)
-        {
-          GNUNET_free (path);
-          return buf;
-        }
-      pos = end + 1;
-    }
-  sprintf (buf, "%s/%s", pos, binary);
-  if (GNUNET_DISK_file_test (buf) == GNUNET_YES)
-    {
-      GNUNET_free (path);
-      return buf;
-    }
-  GNUNET_free (buf);
-  GNUNET_free (path);
-  return NULL;
+  /* FIXME: do we need to track these probe context objects so that
+     we can clean them up on plugin unload? */
+  tcp_probe_ctx
+    = GNUNET_malloc(sizeof(struct TCPProbeContext));
+  tcp_probe_ctx->message.header.size
+    = htons(sizeof(struct TCP_NAT_ProbeMessage));
+  tcp_probe_ctx->message.header.type
+    = htons(GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE);
+  memcpy (&tcp_probe_ctx->message.clientIdentity,
+         plugin->env->my_identity,
+         sizeof(struct GNUNET_PeerIdentity));
+  tcp_probe_ctx->plugin = plugin;
+  tcp_probe_ctx->sock = sock;
+  GNUNET_CONTAINER_DLL_insert (plugin->probe_head,
+                              plugin->probe_tail,
+                              tcp_probe_ctx);
+  tcp_probe_ctx->transmit_handle 
+    = GNUNET_CONNECTION_notify_transmit_ready (sock,
+                                              ntohs (tcp_probe_ctx->message.header.size),
+                                              GNUNET_TIME_UNIT_FOREVER_REL,
+                                              &notify_send_probe, tcp_probe_ctx);
+  
 }
 
-/**
- * Check whether the suid bit is set on a file.
- * Attempts to find the file using the current
- * PATH environment variable as a search path.
- *
- * @param binary the name of the file to check
- */
-static int
-check_gnunet_nat_binary(char *binary)
-{
-  struct stat statbuf;
-  char *p;
-
-  p = get_path_from_PATH (binary);
-  if (p == NULL)
-    return GNUNET_NO;
-  if (0 != STAT (p, &statbuf))
-    {
-      GNUNET_free (p);
-      return GNUNET_SYSERR;
-    }
-  GNUNET_free (p);
-  if ( (0 != (statbuf.st_mode & S_ISUID)) &&
-       (statbuf.st_uid == 0) )
-    return GNUNET_YES;
-  return GNUNET_NO;
-}
 
 /**
  * Entry point for the plugin.
@@ -2263,140 +2018,101 @@ libgnunet_plugin_transport_tcp_init (void *cls)
   struct GNUNET_SERVICE_Context *service;
   unsigned long long aport;
   unsigned long long bport;
+  unsigned long long max_connections;
   unsigned int i;
-  int behind_nat;
-  int allow_nat;
-  int only_nat_addresses;
-  char *internal_address;
-  char *external_address;
-  struct sockaddr_in in_addr;
-  struct IPv4TcpAddress t4;
-
-  service = GNUNET_SERVICE_start ("transport-tcp", env->sched, env->cfg);
-  if (service == NULL)
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                 _("Failed to start service for `%s' transport plugin.\n"),
-                 "tcp");
-      return NULL;
-    }
-
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
-                                                           "transport-tcp",
-                                                           "BEHIND_NAT"))
-    {
-      /* We are behind nat (according to the user) */
-      if (check_gnunet_nat_binary("gnunet-nat-server") == GNUNET_YES)
-        {
-          behind_nat = GNUNET_YES;
-        }
-      else
-        {
-          behind_nat = GNUNET_NO;
-          GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Configuration specified you are behind a NAT, but gnunet-nat-server is not installed properly (suid bit not set)!\n");
-        }
-    }
-  else
-    behind_nat = GNUNET_NO; /* We are not behind nat! */
-
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
-                                                           "transport-tcp",
-                                                           "ALLOW_NAT"))
-    {
-      if (check_gnunet_nat_binary("gnunet-nat-client") == GNUNET_YES)
-        allow_nat = GNUNET_YES; /* We will try to connect to NAT'd peers */
-      else
-      {
-        allow_nat = GNUNET_NO;
-        GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Configuration specified you want to connect to NAT'd peers, but gnunet-nat-client is not installed properly (suid bit not set)!\n");
-      }
-    }
-  else
-    allow_nat = GNUNET_NO; /* We don't want to try to help NAT'd peers */
-
-
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
-                                                           "transport-tcp",
-                                                           "ONLY_NAT_ADDRESSES"))
-    only_nat_addresses = GNUNET_YES; /* We will only report our addresses as NAT'd */
-  else
-    only_nat_addresses = GNUNET_NO; /* We will report our addresses as NAT'd and non-NAT'd */
-
-  external_address = NULL;
-  if (((GNUNET_YES == behind_nat) || (GNUNET_YES == allow_nat)) && (GNUNET_OK !=
-         GNUNET_CONFIGURATION_get_value_string (env->cfg,
-                                                "transport-tcp",
-                                                "EXTERNAL_ADDRESS",
-                                                &external_address)))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                       _
-                       ("Require EXTERNAL_ADDRESS for service `%s' in configuration (either BEHIND_NAT or ALLOW_NAT set to YES)!\n"),
+  struct GNUNET_TIME_Relative idle_timeout;
+  int ret;
+  struct sockaddr **addrs;
+  socklen_t *addrlens;
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_number (env->cfg,
+                                             "transport-tcp",
+                                             "MAX_CONNECTIONS",
+                                             &max_connections))
+    max_connections = 128;
+  
+  aport = 0;
+  if ( (GNUNET_OK !=
+       GNUNET_CONFIGURATION_get_value_number (env->cfg,
+                                              "transport-tcp",
+                                              "PORT",
+                                              &bport)) ||
+       (bport > 65535) ||
+       ((GNUNET_OK ==
+        GNUNET_CONFIGURATION_get_value_number (env->cfg,
+                                               "transport-tcp",
+                                               "ADVERTISED-PORT",
+                                               &aport)) && 
+       (aport > 65535)) )
+    {
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                       _("Require valid port number for service `%s' in configuration!\n"),
                        "transport-tcp");
-      GNUNET_SERVICE_stop (service);
       return NULL;
-    }
-
-  if ((external_address != NULL) && (inet_pton(AF_INET, external_address, &in_addr.sin_addr) != 1))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Malformed EXTERNAL_ADDRESS %s given in configuration!\n", external_address);
-    }
-
-  internal_address = NULL;
-  if ((GNUNET_YES == behind_nat) && (GNUNET_OK !=
-         GNUNET_CONFIGURATION_get_value_string (env->cfg,
-                                                "transport-tcp",
-                                                "INTERNAL_ADDRESS",
-                                                &internal_address)))
+    } 
+  if (aport == 0)
+    aport = bport;
+  if (bport == 0)
+    aport = 0;
+  if (bport != 0)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                 _("Require INTERNAL_ADDRESS for service `%s' in configuration!\n"),
-                 "transport-tcp");
-      GNUNET_SERVICE_stop (service);
-      GNUNET_free_non_null(external_address);
-      return NULL;
+      service = GNUNET_SERVICE_start ("transport-tcp", env->cfg);      
+      if (service == NULL)
+       {
+         GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                          "tcp",
+                          _("Failed to start service.\n"));
+         return NULL;
+       }
     }
+  else
+    service = NULL;
 
-  if ((internal_address != NULL) && (inet_pton(AF_INET, internal_address, &in_addr.sin_addr) != 1))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Malformed INTERNAL_ADDRESS %s given in configuration!\n", internal_address);
-    }
 
-  aport = 0;
-  if ((GNUNET_OK !=
-       GNUNET_CONFIGURATION_get_value_number (env->cfg,
-                                              "transport-tcp",
-                                              "PORT",
-                                              &bport)) ||
-      (bport > 65535) ||
-      ((GNUNET_OK ==
-        GNUNET_CONFIGURATION_get_value_number (env->cfg,
-                                               "transport-tcp",
-                                               "ADVERTISED-PORT",
-                                               &aport)) && (aport > 65535)))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                       _
-                       ("Require valid port number for service `%s' in configuration!\n"),
-                       "transport-tcp");
-      GNUNET_free_non_null(external_address);
-      GNUNET_free_non_null(internal_address);
-      GNUNET_SERVICE_stop (service);
-      return NULL;
-    }
 
-  if (aport == 0)
-    aport = bport;
   plugin = GNUNET_malloc (sizeof (struct Plugin));
+  plugin->max_connections = max_connections;
   plugin->open_port = bport;
   plugin->adv_port = aport;
-  plugin->external_address = external_address;
-  plugin->internal_address = internal_address;
-  plugin->behind_nat = behind_nat;
-  plugin->allow_nat = allow_nat;
-  plugin->only_nat_addresses = only_nat_addresses;
   plugin->env = env;
   plugin->lsock = NULL;
+  if ( (service != NULL) &&
+       (GNUNET_SYSERR !=
+       (ret = GNUNET_SERVICE_get_server_addresses ("transport-tcp",
+                                                   env->cfg,
+                                                   &addrs,
+                                                   &addrlens))) )
+    {
+      plugin->nat = GNUNET_NAT_register (env->cfg,
+                                        GNUNET_YES,
+                                        aport,
+                                        (unsigned int) ret,
+                                        (const struct sockaddr **) addrs,
+                                        addrlens,
+                                        &tcp_nat_port_map_callback,
+                                        &try_connection_reversal,
+                                        plugin);
+      while (ret > 0)
+      {
+        ret--;
+        GNUNET_assert (addrs[ret] != NULL);
+       GNUNET_free (addrs[ret]);
+      }
+      GNUNET_free_non_null (addrs);
+      GNUNET_free_non_null (addrlens);
+    }
+  else
+    {
+      plugin->nat = GNUNET_NAT_register (env->cfg,
+                                        GNUNET_YES,
+                                        0,
+                                        0, NULL, NULL,
+                                        NULL,
+                                        &try_connection_reversal,
+                                        plugin);
+    }
   api = GNUNET_malloc (sizeof (struct GNUNET_TRANSPORT_PluginFunctions));
   api->cls = plugin;
   api->send = &tcp_plugin_send;
@@ -2405,81 +2121,57 @@ libgnunet_plugin_transport_tcp_init (void *cls)
   api->check_address = &tcp_plugin_check_address;
   api->address_to_string = &tcp_address_to_string;
   plugin->service = service;
-  plugin->server = GNUNET_SERVICE_get_server (service);
+  if (service != NULL)   
+    {
+      plugin->server = GNUNET_SERVICE_get_server (service);
+    }
+  else
+    {
+      if (GNUNET_OK !=
+         GNUNET_CONFIGURATION_get_value_time (env->cfg,
+                                              "transport-tcp",
+                                              "TIMEOUT",
+                                              &idle_timeout))
+       {
+         GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                          "tcp",
+                          _("Failed to find option %s in section %s!\n"),
+                          "TIMEOUT",
+                          "transport-tcp");
+         if (plugin->nat != NULL)
+           GNUNET_NAT_unregister (plugin->nat);
+         GNUNET_free (plugin);
+         GNUNET_free (api);
+         return NULL;
+       }
+      plugin->server = GNUNET_SERVER_create_with_sockets (&plugin_tcp_access_check, plugin, NULL,
+                                                         idle_timeout, GNUNET_YES);
+    }
   plugin->handlers = GNUNET_malloc (sizeof (my_handlers));
   memcpy (plugin->handlers, my_handlers, sizeof (my_handlers));
   for (i = 0;
-       i <
-       sizeof (my_handlers) / sizeof (struct GNUNET_SERVER_MessageHandler);
+       i < sizeof (my_handlers) / sizeof (struct GNUNET_SERVER_MessageHandler);
        i++)
     plugin->handlers[i].callback_cls = plugin;
   GNUNET_SERVER_add_handlers (plugin->server, plugin->handlers);
-
-  if (plugin->behind_nat == GNUNET_YES)
-    {
-      if (GNUNET_YES != tcp_transport_start_nat_server(plugin))
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-
-                           _
-                           ("Failed to start %s required for NAT in %s!\n"),
-                           "gnunet-nat-server"
-                           "transport-tcp");
-          GNUNET_free_non_null(external_address);
-          GNUNET_free_non_null(internal_address);
-          GNUNET_SERVICE_stop (service);
-         GNUNET_free (api);
-          return NULL;
-        }
-    }
-
-  if (allow_nat == GNUNET_YES)
-    {
-      plugin->nat_wait_conns = GNUNET_CONTAINER_multihashmap_create(100);
-      GNUNET_assert(plugin->nat_wait_conns != NULL);
-    }
-
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("TCP transport listening on port %llu\n"), bport);
+  GNUNET_SERVER_disconnect_notify (plugin->server,
+                                  &disconnect_notify,
+                                  plugin);    
+  plugin->nat_wait_conns = GNUNET_CONTAINER_multihashmap_create(16);
+  if (bport != 0)
+    GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, 
+                    "tcp",
+                    _("TCP transport listening on port %llu\n"), 
+                    bport);
+  else
+    GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, 
+                    "tcp",
+                    _("TCP transport not listening on any port (client only)\n"));
   if (aport != bport)
-    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+    GNUNET_log_from (GNUNET_ERROR_TYPE_INFO,
+                    "tcp",
                      _("TCP transport advertises itself as being on port %llu\n"),
                      aport);
-  GNUNET_SERVER_disconnect_notify (plugin->server,
-                                  &disconnect_notify,
-                                   plugin);
-  GNUNET_CONFIGURATION_get_value_string(env->cfg, "transport-tcp", "BINDTO", &plugin->bind_address);
-
-  if (plugin->behind_nat == GNUNET_NO)
-    {
-      GNUNET_OS_network_interfaces_list (&process_interfaces, plugin);
-    }
-
-  plugin->hostname_dns = GNUNET_RESOLVER_hostname_resolve (env->sched,
-                                                           env->cfg,
-                                                           AF_UNSPEC,
-                                                           HOSTNAME_RESOLVE_TIMEOUT,
-                                                           &process_hostname_ips,
-                                                           plugin);
-
-  if ((plugin->behind_nat == GNUNET_YES) && (inet_pton(AF_INET, plugin->external_address, &t4.ipv4_addr) == 1))
-    {
-      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Notifying transport of address %s:0\n", plugin->external_address);
-      t4.t_port = htons(0);
-      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (uint32_t));
-      plugin->env->notify_address (plugin->env->cls,
-                                  "tcp",
-                                   &t4, sizeof(t4), GNUNET_TIME_UNIT_FOREVER_REL);
-    }
-  else if ((plugin->external_address != NULL) && (inet_pton(AF_INET, plugin->external_address, &t4.ipv4_addr) == 1))
-    {
-      t4.t_port = htons(plugin->adv_port);
-      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Notifying transport of address %s:%d\n", plugin->external_address, plugin->adv_port);
-      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (uint32_t));
-      plugin->env->notify_address (plugin->env->cls,
-                                   "tcp",
-                                   &t4, sizeof(t4), GNUNET_TIME_UNIT_FOREVER_REL);
-    }
-
   return api;
 }
 
@@ -2493,32 +2185,26 @@ libgnunet_plugin_transport_tcp_done (void *cls)
   struct GNUNET_TRANSPORT_PluginFunctions *api = cls;
   struct Plugin *plugin = api->cls;
   struct Session *session;
-  struct LocalAddrList *lal;
+  struct TCPProbeContext *tcp_probe;
 
   while (NULL != (session = plugin->sessions))
     disconnect_session (session);
-  if (NULL != plugin->hostname_dns)
-    {
-      GNUNET_RESOLVER_request_cancel (plugin->hostname_dns);
-      plugin->hostname_dns = NULL;
-    }
-  GNUNET_SERVICE_stop (plugin->service);
+  if (plugin->service != NULL)
+    GNUNET_SERVICE_stop (plugin->service);
+  else
+    GNUNET_SERVER_destroy (plugin->server);
   GNUNET_free (plugin->handlers);
-  while (NULL != (lal = plugin->lal_head))
-    {
-      GNUNET_CONTAINER_DLL_remove (plugin->lal_head,
-                                  plugin->lal_tail,
-                                  lal);
-      GNUNET_free (lal);
-    }
-
-  if (plugin->behind_nat == GNUNET_YES)
+  if (plugin->nat != NULL)
+    GNUNET_NAT_unregister (plugin->nat);
+  while (NULL != (tcp_probe = plugin->probe_head))
     {
-      if (0 != PLIBC_KILL (plugin->server_pid, SIGTERM))
-        GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "kill");
-      GNUNET_OS_process_wait (plugin->server_pid);
+      GNUNET_CONTAINER_DLL_remove (plugin->probe_head,
+                                  plugin->probe_tail,
+                                  tcp_probe);
+      GNUNET_CONNECTION_destroy (tcp_probe->sock, GNUNET_NO);
+      GNUNET_free (tcp_probe);
     }
-  GNUNET_free_non_null(plugin->bind_address);
+  GNUNET_CONTAINER_multihashmap_destroy (plugin->nat_wait_conns);
   GNUNET_free (plugin);
   GNUNET_free (api);
   return NULL;