wip
[oweals/gnunet.git] / src / transport / plugin_transport_tcp.c
index 208a113f4c78a781bfcd68ff4b63b17f5bf0332f..9dc67dcdf4eb098305c64658889e0fa9a2493da6 100644 (file)
@@ -26,6 +26,7 @@
 #include "gnunet_hello_lib.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_NO
+
 #define DEBUG_TCP_NAT GNUNET_NO
-#define MULTIPLE_PEER_SESSIONS GNUNET_YES
+
 /**
  * How long until we give up on transmitting the welcome message?
  */
@@ -63,6 +65,7 @@ struct WelcomeMessage
 
 };
 
+
 /**
  * Basically a WELCOME message, but with the purpose
  * of giving the waiting peer a client handle to use
@@ -81,11 +84,23 @@ 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.
    */
@@ -143,6 +158,7 @@ struct IPv6TcpAddress
 
 };
 
+
 /**
  * Encapsulation of all of the state of the plugin.
  */
@@ -166,6 +182,27 @@ struct LocalAddrList
    */
   struct LocalAddrList *prev;
 
+  /**
+   * Link to plugin.
+   */
+  struct Plugin *plugin;
+
+  /**
+   * Handle to NAT holes we've tried to punch for this address.
+   */
+  struct GNUNET_NAT_Handle *nat;
+
+  /**
+   * Pointer to a 'struct IPv4/V6TcpAddress' describing our external IP and port
+   * as obtained from the NAT by automatic port mapping.
+   */
+  void *external_nat_address;
+
+  /**
+   * Number of bytes in 'external_nat_address'
+   */
+  size_t ena_size;
+
   /**
    * Number of bytes of the address that follow
    */
@@ -345,7 +382,7 @@ struct Plugin
   /**
    * The process id of the server process (if behind NAT)
    */
-  pid_t server_pid;
+  struct GNUNET_OS_Process *server_proc;
 
   /**
    * List of open TCP sessions.
@@ -379,13 +416,15 @@ struct Plugin
   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.
+   * The external address given to us by the user.  Used for HELLOs
+   * and address validation.
    */
   char *external_address;
 
   /**
    * The internal address given to us by the user (or discovered).
+   * Used for NAT traversal (ICMP method), but not as a 'validateable'
+   * address in HELLOs.
    */
   char *internal_address;
 
@@ -404,6 +443,21 @@ struct Plugin
    */
   struct LocalAddrList *lal_tail;
 
+  /**
+   * List of active TCP probes.
+   */
+  struct TCPProbeContext *probe_head;
+
+  /**
+   * List of active TCP probes.
+   */
+  struct TCPProbeContext *probe_tail;
+
+  /**
+   * Handle for (DYN)DNS lookup of our external IP.
+   */
+  struct GNUNET_RESOLVER_RequestHandle *ext_dns;
+
   /**
    * ID of task used to update our addresses when one expires.
    */
@@ -425,27 +479,114 @@ struct Plugin
    */
   int behind_nat;
 
+  /**
+   * Has the NAT been punched?
+   */
+  int nat_punched;
+
   /**
    * Is this transport configured to allow connections to NAT'd peers?
    */
-  int allow_nat;
+  int enable_nat_client;
 
   /**
-   * Should this transport advertise only NAT addresses (port set to 0)?
-   * If not, all addresses will be duplicated for NAT punching and regular
-   * ports.
+   * Should we run the gnunet-nat-server?
    */
-  int only_nat_addresses;
+  int enable_nat_server;
+
+  /**
+   * Are we allowed to try UPnP/PMP for NAT traversal?
+   */
+  int enable_upnp;
 
 };
 
 
+/**
+ * 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
+nat_port_map_callback (void *cls,
+                      int add_remove,
+                      const struct sockaddr *addr,
+                      socklen_t addrlen)
+{
+  struct LocalAddrList *lal = cls;
+  struct Plugin *plugin = lal->plugin;
+  int af;
+  struct IPv4TcpAddress t4;
+  struct IPv6TcpAddress t6;
+  void *arg;
+  uint16_t args;
+
+  /* convert 'addr' to our internal format */
+  af = addr->sa_family;
+  switch (af)
+    {
+    case AF_INET:
+      t4.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
+      t6.t6_port = ((struct sockaddr_in *) addr)->sin_port;
+      arg = &t4;
+      args = sizeof (t4);
+      break;
+    case AF_INET6:
+      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;
+    } 
+
+  /* modify our published address list */
+  if (GNUNET_YES == add_remove)
+    {
+      plugin->env->notify_address (plugin->env->cls,
+                                   "tcp",
+                                   arg, args, GNUNET_TIME_UNIT_FOREVER_REL);
+      GNUNET_free_non_null (lal->external_nat_address);
+      lal->external_nat_address = GNUNET_memdup (arg, args);
+      lal->ena_size = args;
+    }
+  else
+    {
+      plugin->env->notify_address (plugin->env->cls,
+                                   "tcp",
+                                   arg, args, GNUNET_TIME_UNIT_ZERO);
+      GNUNET_free_non_null (lal->external_nat_address);
+      lal->ena_size = 0;
+    }
+}
+
+
+/**
+ * Add the given address to the list of 'local' addresses, thereby
+ * making it a 'legal' address for this peer to have.  
+ * 
+ * @param plugin the plugin
+ * @param arg the address, either an IPv4 or an IPv6 IP address
+ * @param arg_size number of bytes in arg
+ */
 static void
 add_to_address_list (struct Plugin *plugin,
                     const void *arg,
                     size_t arg_size)
 {
   struct LocalAddrList *lal;
+  struct sockaddr_in v4;
+  struct sockaddr_in6 v6;
+  const struct sockaddr *sa;
+  socklen_t salen;
 
   lal = plugin->lal_head;
   while (NULL != lal)
@@ -456,14 +597,59 @@ add_to_address_list (struct Plugin *plugin,
       lal = lal->next;
     }
   lal = GNUNET_malloc (sizeof (struct LocalAddrList) + arg_size);
+  lal->plugin = plugin;
   lal->size = arg_size;
   memcpy (&lal[1], arg, arg_size);
   GNUNET_CONTAINER_DLL_insert (plugin->lal_head,
                               plugin->lal_tail,
                               lal);
+  if (plugin->open_port == 0)
+    return; /* we're not listening at all... */
+  if (arg_size == sizeof (struct in_addr))
+    {
+      memset (&v4, 0, sizeof (v4));
+      v4.sin_family = AF_INET;
+      v4.sin_port = htons (plugin->open_port);
+      memcpy (&v4.sin_addr, arg, arg_size);
+#if HAVE_SOCKADDR_IN_SIN_LEN
+      v4.sin_len = sizeof (struct sockaddr_in);
+#endif
+      sa = (const struct sockaddr*) &v4;
+      salen = sizeof (v4);
+    }
+  else if (arg_size == sizeof (struct in6_addr))
+    {     
+      memset (&v6, 0, sizeof (v6));
+      v6.sin6_family = AF_INET6;
+      v6.sin6_port = htons (plugin->open_port);
+      memcpy (&v6.sin6_addr, arg, arg_size);
+#if HAVE_SOCKADDR_IN_SIN_LEN
+      v6.sin6_len = sizeof (struct sockaddr_in6);
+#endif
+      sa = (const struct sockaddr*) &v6;
+      salen = sizeof (v6);
+    }
+  else
+    {
+      GNUNET_break (0);
+      return;
+    }
+  if ( (plugin->behind_nat == GNUNET_YES) &&
+       (plugin->enable_upnp == GNUNET_YES) )
+    lal->nat = GNUNET_NAT_register (sa, salen,
+                                   &nat_port_map_callback,
+                                   lal);
 }
 
 
+/**
+ * Check if the given address is in the list of 'local' addresses.
+ * 
+ * @param plugin the plugin
+ * @param arg the address, either an IPv4 or an IPv6 IP address
+ * @param arg_size number of bytes in arg
+ * @return GNUNET_OK if this is one of our IPs, GNUNET_SYSERR if not
+ */
 static int
 check_local_addr (struct Plugin *plugin,
                  const void *arg,
@@ -483,6 +669,33 @@ check_local_addr (struct Plugin *plugin,
 }
 
 
+/**
+ * Check if the given address is in the list of 'mapped' addresses.
+ * 
+ * @param plugin the plugin
+ * @param arg the address, either a 'struct IPv4TcpAddress' or a 'struct IPv6TcpAddress'
+ * @param arg_size number of bytes in arg
+ * @return GNUNET_OK if this is one of our IPs, GNUNET_SYSERR if not
+ */
+static int
+check_mapped_addr (struct Plugin *plugin,
+                  const void *arg,
+                  size_t arg_size)
+{
+  struct LocalAddrList *lal;
+
+  lal = plugin->lal_head;
+  while (NULL != lal)
+    {
+      if ( (lal->ena_size == arg_size) &&
+          (0 == memcmp (lal->external_nat_address, arg, arg_size)) )
+       return GNUNET_OK;
+      lal = lal->next;
+    }
+  return GNUNET_SYSERR;
+}
+
+
 /**
  * Function called for a quick conversion of the binary address to
  * a numeric address.  Note that the caller must not free the
@@ -527,9 +740,10 @@ tcp_address_to_string (void *cls,
     }
   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\n"),
+                      addrlen);
       GNUNET_break (0);
       return NULL;
     }
@@ -550,6 +764,8 @@ 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 *
@@ -564,29 +780,11 @@ find_session_by_client (struct Plugin *plugin,
   return ret;
 }
 
-#if !MULTIPLE_PEER_SESSIONS
-/**
- * Find the session handle for the given client.
- *
- * @return NULL if no matching session exists
- */
-static struct Session *
-find_session_by_id (struct Plugin *plugin,
-                    const struct GNUNET_PeerIdentity *peer)
-{
-  struct Session *ret;
-
-  ret = plugin->sessions;
-  while ((ret != NULL) && (0 != memcmp(peer, &ret->target, sizeof(struct GNUNET_PeerIdentity))))
-    ret = ret->next;
-  return ret;
-}
-#endif
 
 /**
  * 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
@@ -597,7 +795,8 @@ find_session_by_id (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;
@@ -607,9 +806,9 @@ create_session (struct Plugin *plugin,
     GNUNET_assert (client != NULL);
   else
     GNUNET_assert (client == NULL);
-
 #if DEBUG_TCP
-  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
                   "Creating new session for peer `%4s'\n",
                   GNUNET_i2s (target));
 #endif
@@ -687,7 +886,8 @@ do_transmit (void *cls, size_t size, void *buf)
   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
@@ -697,13 +897,14 @@ 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));
@@ -775,8 +976,10 @@ 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"),
@@ -831,14 +1034,14 @@ 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;
@@ -865,12 +1068,11 @@ 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,
@@ -892,13 +1094,12 @@ 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) 
+  else if (session->client != NULL)
     GNUNET_SERVER_client_drop (session->client);
   GNUNET_STATISTICS_update (session->plugin->env->stats,
                            gettext_noop ("# TCP sessions active"),
@@ -930,9 +1131,9 @@ 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) )
@@ -946,59 +1147,60 @@ 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
+ * 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
+ * @param sa the address of the peer (IPv4-only)
  */
-void
-run_gnunet_nat_client (struct Plugin *plugin, const char *addr, size_t addrlen)
+static void
+run_gnunet_nat_client (struct Plugin *plugin, 
+                      const struct sockaddr_in *sa)
 {
   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
+  char port_as_string[6];
+  struct GNUNET_OS_Process *proc;
 
-  if (addrlen < sizeof (struct sockaddr))
-    return;
-
-  switch (sa->sa_family)
+  if (plugin->internal_address == NULL)
     {
-    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:
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Internal IP address not known, cannot use ICMP NAT traversal method\n"));
       return;
     }
-
-  GNUNET_asprintf(&port_as_string, "%d", plugin->adv_port);
+  GNUNET_assert (sa->sin_family == AF_INET);
+  if (NULL == inet_ntop (AF_INET,
+                        &sa->sin_addr,
+                        inet4, INET_ADDRSTRLEN))
+    {
+      GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "inet_ntop");
+      return;
+    }
+  GNUNET_snprintf(port_as_string, 
+                 sizeof (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);
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  _("Running gnunet-nat-client %s %s %u\n"), 
+                  plugin->internal_address,
+                  inet4,
+                  (unsigned int) 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);
+  proc = GNUNET_OS_start_process (NULL, 
+                                 NULL, 
+                                 "gnunet-nat-client",
+                                 "gnunet-nat-client",
+                                 plugin->internal_address, 
+                                 inet4,
+                                 port_as_string, 
+                                 NULL);
+  if (NULL == proc)
+    return;
+  /* we know that the gnunet-nat-client will terminate virtually
+     instantly */
+  GNUNET_OS_process_wait (proc);
+  GNUNET_OS_process_close (proc);
 }
 
 
@@ -1101,14 +1303,8 @@ tcp_plugin_send (void *cls,
              GNUNET_break (0);
              break;
            }
-#if IGNORE_INBOUND
-         if (session->inbound == GNUNET_YES) /* FIXME: why do we ignore inbound sessions? */
-           {
-              GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Ignoring inbound session\n");
-              continue;
-           }
-#endif
-         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,
@@ -1123,8 +1319,9 @@ 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,
@@ -1171,7 +1368,8 @@ 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);
@@ -1182,16 +1380,20 @@ tcp_plugin_send (void *cls,
         return -1; /* NAT client only works with IPv4 addresses */
 
 
-      if ((plugin->allow_nat == GNUNET_YES) && (is_natd == GNUNET_YES) &&
-           (GNUNET_NO == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, &target->hashPubKey)))
+      if ( (plugin->enable_nat_client == GNUNET_YES) && 
+          (is_natd == GNUNET_YES) &&
+           (GNUNET_NO == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns,
+                                                               &target->hashPubKey)) )
         {
 #if DEBUG_TCP_NAT
-          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+          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);
 
           /* create new message entry */
           pm = GNUNET_malloc (sizeof (struct PendingMessage) + msgbuf_size);
@@ -1211,27 +1413,34 @@ 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_WARNING,
+          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);
+          run_gnunet_nat_client (plugin, &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 ( (plugin->enable_nat_client == GNUNET_YES) && 
+          (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));
@@ -1243,7 +1452,8 @@ tcp_plugin_send (void *cls,
          return -1;
        }
 #if DEBUG_TCP_NAT
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+      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));
@@ -1251,7 +1461,8 @@ 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,
@@ -1279,7 +1490,8 @@ 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));
@@ -1315,7 +1527,8 @@ 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
@@ -1454,8 +1667,7 @@ 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,
+  GNUNET_RESOLVER_hostname_get (plugin->env->cfg,
                                 sb,
                                 sbs,
                                 !numeric, timeout, &append_port, ppc);
@@ -1463,24 +1675,19 @@ tcp_plugin_address_pretty_printer (void *cls,
 
 
 /**
- * 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;
@@ -1520,14 +1727,15 @@ tcp_plugin_check_address (void *cls,
   if (addrlen == sizeof (struct IPv4TcpAddress))
     {
       v4 = (struct IPv4TcpAddress *) addr;
+      if (GNUNET_OK ==
+         check_mapped_addr (plugin, v4, sizeof (struct IPv4TcpAddress)))
+       return GNUNET_OK;
       if (GNUNET_OK !=
          check_port (plugin, ntohs (v4->t_port)))
        return GNUNET_SYSERR;
       if (GNUNET_OK !=
-         check_local_addr (plugin, &v4->ipv4_addr, sizeof (uint32_t)))
-       {
-         return GNUNET_SYSERR;
-       }
+         check_local_addr (plugin, &v4->ipv4_addr, sizeof (struct in_addr)))
+       return GNUNET_SYSERR;   
     }
   else
     {
@@ -1537,18 +1745,20 @@ tcp_plugin_check_address (void *cls,
          GNUNET_break_op (0);
          return GNUNET_SYSERR;
        }
+      if (GNUNET_OK ==
+         check_mapped_addr (plugin, v6, sizeof (struct IPv6TcpAddress)))
+       return GNUNET_OK;
       if (GNUNET_OK !=
          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;
-       }
+       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
@@ -1560,12 +1770,12 @@ 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;
@@ -1574,7 +1784,9 @@ 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 tcp 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
@@ -1584,84 +1796,96 @@ 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);
       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;
+  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 session for NAT probe!\n");
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                      "Did NOT find 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;
-
-      if (GNUNET_OK ==
-          GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
-        {
+      GNUNET_SERVER_receive_done (client, GNUNET_OK);
+      return;
+    }
 #if DEBUG_TCP_NAT
-          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                           "handle_tcp_nat_probe Found address `%s' for incoming connection %p\n",
-                           GNUNET_a2s (vaddr, alen),
-                           client);
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                  "tcp",
+                  "Found 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_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;
+    }
+
+  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 (GNUNET_ERROR_TYPE_DEBUG,
-                          "Bad address for incoming connection!\n");
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  "Found address `%s' for incoming connection\n",
+                  GNUNET_a2s (vaddr, alen));
 #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);
-    }
-  else
+  switch (((const struct sockaddr *)vaddr)->sa_family)
     {
+    case 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);
+      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.
@@ -1686,41 +1910,41 @@ handle_tcp_welcome (void *cls,
   const struct sockaddr_in6 *s6;
 
 #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);
-#if MULTIPLE_PEER_SESSIONS
   session = find_session_by_client (plugin, client);
-#else
-  session = find_session_by_id(plugin, &wm->clientIdentity);
-#endif
 
   if (session == NULL)
     {
-      GNUNET_SERVER_client_keep (client);
 #if DEBUG_TCP_NAT
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                       "Received %s message from a `%4s/%p', creating session\n",
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                       "Received %s message from a `%4s', creating new session\n",
                        "WELCOME",
-                       GNUNET_i2s (&wm->clientIdentity), client);
+                       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_NAT
-         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                          "Found address `%s' for incoming connection %p\n",
-                          GNUNET_a2s (vaddr, alen),
-                          client);
+         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))
            {
@@ -1748,15 +1972,11 @@ handle_tcp_welcome (void *cls,
       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
@@ -1765,22 +1985,20 @@ handle_tcp_welcome (void *cls,
     if (GNUNET_OK ==
         GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
       {
-        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                    "Found address `%s' (already have session) for incoming connection %p\n",
-                    GNUNET_a2s (vaddr, alen),
-                    client);
+        GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                        "tcp",
+                        "Found address `%s' (already have session)\n",
+                        GNUNET_a2s (vaddr, alen));
       }
 #endif
     }
 
-#if MULTIPLE_PEER_SESSIONS
   if (session->expecting_welcome != GNUNET_YES)
     {
       GNUNET_break_op (0);
       GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
       return;
     }
-#endif
   session->last_activity = GNUNET_TIME_absolute_get ();
   session->expecting_welcome = GNUNET_NO;
   GNUNET_SERVER_receive_done (client, GNUNET_OK);
@@ -1795,7 +2013,8 @@ 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;
@@ -1803,15 +2022,15 @@ 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);
 }
 
 
@@ -1831,22 +2050,26 @@ 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 > 1
-  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+  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),
@@ -1856,16 +2079,22 @@ 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)
+  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);
+      GNUNET_SCHEDULER_add_delayed (delay, &delayed_done, session);
 }
 
 
@@ -1889,14 +2118,14 @@ disconnect_notify (void *cls,
   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
   disconnect_session (session);
 }
@@ -1904,7 +2133,7 @@ disconnect_notify (void *cls,
 
 /**
  * Add the IP of our network interface to the list of
- * our external IP addresses.
+ * our internal IP addresses.
  *
  * @param cls the 'struct Plugin*'
  * @param name name of the interface
@@ -1932,32 +2161,45 @@ process_interfaces (void *cls,
 
   af = addr->sa_family;
   arg_nat = NULL;
-  if (af == AF_INET)
+  switch (af)
     {
+    case 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_assert (NULL != inet_ntop(AF_INET, 
+                                      &t4.ipv4_addr, 
+                                      buf, 
+                                      sizeof (buf)));
+      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));
+#if DEBUG_TCP
+          GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                          "tcp",
+                          "Not notifying transport of address `%s' (redundant)\n",
+                          GNUNET_a2s (addr, addrlen));
+#endif
           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 */
+      if ( (plugin->internal_address == NULL) &&
+          (isDefault) )        
+       plugin->internal_address = GNUNET_strdup (buf); 
+      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (struct in_addr));
+      if (plugin->behind_nat == GNUNET_YES) 
         {
+         /* Also advertise as NAT (with port 0) */
           t4_nat.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
-          t4_nat.t_port = htons(plugin->adv_port);
+          t4_nat.t_port = htons(0);
           arg_nat = &t4_nat;
-        }
-      else
-        t4.t_port = htons (plugin->adv_port);
+        }      
+      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")))
+      break;
+    case 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;
@@ -1965,40 +2207,42 @@ process_interfaces (void *cls,
       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 */
+      add_to_address_list (plugin, 
+                          &t6.ipv6_addr, 
+                          sizeof (struct in6_addr));
+      if (plugin->behind_nat == GNUNET_YES)
         {
+         /* Also advertise as NAT (with port 0) */
           memcpy (&t6_nat.ipv6_addr,
                   &((struct sockaddr_in6 *) addr)->sin6_addr,
                   sizeof (struct in6_addr));
-          t6_nat.t6_port = htons(plugin->adv_port);
+          t6_nat.t6_port = htons(0);
           arg_nat = &t6;
         }
-      else
-        t6.t6_port = htons (plugin->adv_port);
+      t6.t6_port = htons (plugin->adv_port);
       arg = &t6;
       args = sizeof (t6);
-    }
-  else
-    {
+      break;
+    default:
       GNUNET_break (0);
       return GNUNET_OK;
     }
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _("Found address `%s' (%s) len %d\n"),
+#if DEBUG_TCP
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  "Found address `%s' (%s) len %d\n",
                    GNUNET_a2s (addr, addrlen), name, args);
-
+#endif
   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);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                      _("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);
@@ -2032,66 +2276,81 @@ process_hostname_ips (void *cls,
   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.
  *
+ * @param cls the plugin handle
+ * @param tc the scheduling context
  */
 static void
-tcp_plugin_server_read (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+tcp_plugin_server_read (void *cls, 
+                       const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
   struct Plugin *plugin = cls;
   char mybuf[40];
   ssize_t bytes;
-  memset(&mybuf, 0, sizeof(mybuf));
-  int i;
+  size_t i;
   int port;
-  char *port_start;
-  struct sockaddr_in in_addr;
+  const char *port_start;
+  struct sockaddr_in sin_addr;
   struct TCPProbeContext *tcp_probe_ctx;
   struct GNUNET_CONNECTION_Handle *sock;
 
-  if (tc->reason == GNUNET_SCHEDULER_REASON_SHUTDOWN)
+  if ( (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN) != 0)
     return;
-
-  bytes = GNUNET_DISK_file_read(plugin->server_stdout_handle, &mybuf, sizeof(mybuf));
-
+  memset (mybuf, 0, sizeof(mybuf));
+  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);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                      "tcp",
+                      "Finished reading from server stdout with code: %d\n", 
+                      bytes);
 #endif
+      /* FIXME: consider process_wait here? */
       return;
     }
 
@@ -2099,136 +2358,163 @@ tcp_plugin_server_read (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc
   for (i = 0; i < sizeof(mybuf); i++)
     {
       if (mybuf[i] == '\n')
-        mybuf[i] = '\0';
-
-      if ((mybuf[i] == ':') && (i + 1 < sizeof(mybuf)))
+       {
+         mybuf[i] = '\0';
+         break;
+       }
+      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);
+  /* construct socket address of sender */
+  memset (&sin_addr, 0, sizeof (sin_addr));
+  sin_addr.sin_family = AF_INET;
+#if HAVE_SOCKADDR_IN_SIN_LEN
+  sin_addr.sin_len = sizeof (sin_addr);
+#endif
+  if ( (NULL == port_start) ||
+       (1 != sscanf (port_start, "%d", &port)) ||
+       (-1 == inet_pton(AF_INET, mybuf, &sin_addr.sin_addr)) )
+    {
+      /* should we restart gnunet-nat-server? */
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("gnunet-nat-server generated malformed address `%s'\n"),
+                      mybuf);
+      plugin->server_read_task 
+       = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
+                                         plugin->server_stdout_handle,
+                                         &tcp_plugin_server_read, 
+                                         plugin);
       return;
     }
-
+  sin_addr.sin_port = htons((uint16_t) port);
 #if DEBUG_TCP_NAT
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  _("nat-server-read read: %s port %d\n"), &mybuf, port);
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  "gnunet-nat-server read: %s:%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, 
+                                                (const struct sockaddr *)&sin_addr,
+                                                 sizeof (sin_addr));
   if (sock == NULL)
     {
+      /* failed for some odd reason (out of sockets?); ignore attempt */
       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);
+          GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
+                                          plugin->server_stdout_handle, 
+                                         &tcp_plugin_server_read, 
+                                         plugin);
       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);*/
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "Sending TCP probe message to `%s:%u'!\n", 
+                  mybuf,
+                  (unsigned int) port);  
+  /* 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);
+  
   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);
+      GNUNET_SCHEDULER_add_read_file (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)
+tcp_transport_start_nat_server (struct Plugin *plugin)
 {
-
-  plugin->server_stdout = GNUNET_DISK_pipe(GNUNET_YES);
+  if (plugin->internal_address == NULL)
+    return GNUNET_SYSERR;
+  plugin->server_stdout = GNUNET_DISK_pipe (GNUNET_YES,
+                                           GNUNET_NO,
+                                           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);
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp"
+                   "Starting %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
+  plugin->server_proc = GNUNET_OS_start_process (NULL,
+                                                plugin->server_stdout,
+                                                "gnunet-nat-server", 
+                                                "gnunet-nat-server", 
+                                                plugin->internal_address, 
+                                                NULL);
+  if (plugin->server_proc == NULL)
+    {
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Failed to start %s\n"),
+                      "gnunet-nat-server");
+      GNUNET_DISK_pipe_close (plugin->server_stdout);
+      plugin->server_stdout = NULL;    
       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);
+  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 (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
+ * @return path to binary, NULL if not found
  */
 static char *
-get_path_from_PATH (char *binary)
+get_path_from_PATH (const char *binary)
 {
   char *path;
   char *pos;
@@ -2238,12 +2524,17 @@ get_path_from_PATH (char *binary)
 
   p = getenv ("PATH");
   if (p == NULL)
-    return NULL;
+    {
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                      _("PATH environment variable is unset.\n"));
+      return NULL;
+    }
   path = GNUNET_strdup (p);     /* because we write on it */
   buf = GNUNET_malloc (strlen (path) + 20);
   pos = path;
 
-  while (NULL != (end = strchr (pos, ':')))
+  while (NULL != (end = strchr (pos, PATH_SEPARATOR)))
     {
       *end = '\0';
       sprintf (buf, "%s/%s", pos, binary);
@@ -2265,34 +2556,123 @@ get_path_from_PATH (char *binary)
   return NULL;
 }
 
+
 /**
  * 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
+ * @return GNUNET_YES if the file is SUID, 
+ *         GNUNET_NO if not, 
+ *         GNUNET_SYSERR on error
  */
 static int
-check_gnunet_nat_binary(char *binary)
+check_gnunet_nat_binary (const char *binary)
 {
   struct stat statbuf;
   char *p;
+#ifdef MINGW
+  SOCKET rawsock;
+  char *binaryexe;
 
+  GNUNET_asprintf (&binaryexe, "%s.exe", binary);
+  p = get_path_from_PATH (binaryexe);
+  free (binaryexe);
+#else
   p = get_path_from_PATH (binary);
+#endif
   if (p == NULL)
-    return GNUNET_NO;
+    {
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                      _("Could not find binary `%s' in PATH!\n"),
+                      binary);
+      return GNUNET_NO;
+    }
   if (0 != STAT (p, &statbuf))
     {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, 
+                 _("stat (%s) failed: %s\n"), 
+                 p,
+                 STRERROR (errno));
       GNUNET_free (p);
       return GNUNET_SYSERR;
     }
   GNUNET_free (p);
+#ifndef MINGW
   if ( (0 != (statbuf.st_mode & S_ISUID)) &&
        (statbuf.st_uid == 0) )
     return GNUNET_YES;
   return GNUNET_NO;
+#else
+  rawsock = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);
+  if (INVALID_SOCKET == rawsock)
+    {
+      DWORD err = GetLastError ();
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, 
+                      "tcp",
+                      "socket (AF_INET, SOCK_RAW, IPPROTO_ICMP) failed! GLE = %d\n", err);
+      return GNUNET_NO; /* not running as administrator */
+    }
+  closesocket (rawsock);
+  return GNUNET_YES;
+#endif
 }
 
+
+/**
+ * Our (external) hostname was resolved.
+ *
+ * @param cls the 'struct Plugin'
+ * @param addr NULL on error, otherwise result of DNS lookup
+ * @param addrlen number of bytes in addr
+ */
+static void
+process_external_ip (void *cls,
+                    const struct sockaddr *addr,
+                    socklen_t addrlen)
+{
+  struct Plugin *plugin = cls;
+  const struct sockaddr_in *s;
+  struct IPv4TcpAddress t4;
+
+
+  plugin->ext_dns = NULL;
+  if (addr == NULL)
+    return;
+  GNUNET_assert (addrlen == sizeof (struct sockaddr_in));
+  s = (const struct sockaddr_in *) addr;
+  t4.ipv4_addr = s->sin_addr.s_addr;
+  if ( (plugin->behind_nat == GNUNET_YES) &&
+       (plugin->enable_nat_server == GNUNET_YES) )
+    {
+      t4.t_port = htons(0);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                      "tcp",
+                      "Notifying transport of address %s:%d\n", 
+                      plugin->external_address,
+                      0);
+    }
+  else
+    {
+      t4.t_port = htons(plugin->adv_port);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                      "tcp",
+                      "Notifying transport of address %s:%d\n",
+                      plugin->external_address, 
+                      (int) plugin->adv_port);
+    }
+  add_to_address_list (plugin, 
+                      &t4.ipv4_addr, 
+                      sizeof (struct in_addr));
+  plugin->env->notify_address (plugin->env->cls,
+                              "tcp",
+                              &t4, sizeof(t4),
+                              GNUNET_TIME_UNIT_FOREVER_REL);
+}
+
+
 /**
  * Entry point for the plugin.
  *
@@ -2317,136 +2697,164 @@ libgnunet_plugin_transport_tcp_init (void *cls)
   unsigned long long bport;
   unsigned int i;
   int behind_nat;
-  int allow_nat;
-  int only_nat_addresses;
+  int nat_punched;
+  int enable_nat_client;
+  int enable_nat_server;
+  int enable_upnp;
   char *internal_address;
   char *external_address;
   struct sockaddr_in in_addr;
-  struct IPv4TcpAddress t4;
+  struct GNUNET_TIME_Relative idle_timeout;
+
+  behind_nat = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                    "transport-tcp",
+                                                    "BEHIND_NAT");
+  nat_punched = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                     "transport-tcp",
+                                                     "NAT_PUNCHED");
+  enable_nat_client = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                           "transport-tcp",
+                                                           "ENABLE_NAT_CLIENT");
+  enable_nat_server = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                           "transport-tcp",
+                                                           "ENABLE_NAT_SERVER");
+  enable_upnp = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                     "transport-tcp",
+                                                     "ENABLE_UPNP");
+  
+  if ( (GNUNET_YES == enable_nat_server) &&
+       (GNUNET_YES != check_gnunet_nat_binary("gnunet-nat-server")) )
+    {
+      enable_nat_server = GNUNET_NO;
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("Configuration requires `%s', but binary is not installed properly (SUID bit not set).  Option disabled.\n"),
+                 "gnunet-nat-server");        
+    }
 
-  service = GNUNET_SERVICE_start ("transport-tcp", env->sched, env->cfg);
-  if (service == NULL)
+  if ( (GNUNET_YES == enable_nat_client) &&
+       (GNUNET_YES != check_gnunet_nat_binary("gnunet-nat-client")) )
     {
+      enable_nat_client = GNUNET_NO;
       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                 _("Failed to start service for `%s' transport plugin.\n"),
-                 "tcp");
-      return NULL;
+                 _("Configuration requires `%s', but binary is not installed properly (SUID bit not set).  Option disabled.\n"),
+                 "gnunet-nat-client"); 
     }
-
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
-                                                           "transport-tcp",
-                                                           "BEHIND_NAT"))
+  
+  external_address = NULL;
+  if (GNUNET_OK ==
+      GNUNET_CONFIGURATION_have_value (env->cfg,
+                                      "transport-tcp",
+                                      "EXTERNAL_ADDRESS"))
     {
-      /* 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");
-        }
+      (void) GNUNET_CONFIGURATION_get_value_string (env->cfg,
+                                                   "transport-tcp",
+                                                   "EXTERNAL_ADDRESS",
+                                                   &external_address);
     }
-  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 ( (external_address != NULL) && 
+       (inet_pton(AF_INET, external_address, &in_addr.sin_addr) != 1) ) 
     {
-      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");
-      }
+      
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Malformed %s `%s' given in configuration!\n"), 
+                      "EXTERNAL_ADDRESS",
+                      external_address);
+      return NULL;   
     }
-  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"),
-                       "transport-tcp");
-      GNUNET_SERVICE_stop (service);
-      return NULL;
+  if ( (external_address == NULL) &&
+       (nat_punched == GNUNET_YES) )
+    {
+      nat_punched = GNUNET_NO;
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("Configuration says NAT was punched, but `%s' is not given.  Option ignored.\n"),
+                 "EXTERNAL_ADDRESS");  
     }
 
-  if ((external_address != NULL) && (inet_pton(AF_INET, external_address, &in_addr.sin_addr) != 1))
+  if (GNUNET_YES == nat_punched)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Malformed EXTERNAL_ADDRESS %s given in configuration!\n", external_address);
+      enable_nat_server = GNUNET_NO;
+      enable_upnp = GNUNET_NO;
     }
 
   internal_address = NULL;
-  if ((GNUNET_YES == behind_nat) && (GNUNET_OK !=
-         GNUNET_CONFIGURATION_get_value_string (env->cfg,
-                                                "transport-tcp",
-                                                "INTERNAL_ADDRESS",
-                                                &internal_address)))
-    {
-      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;
+  if (GNUNET_OK ==
+      GNUNET_CONFIGURATION_have_value (env->cfg,
+                                      "transport-tcp",
+                                      "INTERNAL_ADDRESS"))
+    {
+      (void) GNUNET_CONFIGURATION_get_value_string (env->cfg,
+                                                   "transport-tcp",
+                                                   "INTERNAL_ADDRESS",
+                                                   &internal_address);
     }
 
-  if ((internal_address != NULL) && (inet_pton(AF_INET, internal_address, &in_addr.sin_addr) != 1))
+  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);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Malformed %s `%s' given in configuration!\n"), 
+                      "INTERNAL_ADDRESS",
+                      internal_address);      
+      GNUNET_free_non_null(internal_address);
+      GNUNET_free_non_null(external_address);
+      return NULL;
     }
 
   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"),
+  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_free_non_null(external_address);
       GNUNET_free_non_null(internal_address);
-      GNUNET_SERVICE_stop (service);
       return NULL;
     }
 
   if (aport == 0)
     aport = bport;
+  if (bport == 0)
+    aport = 0;
+
+  if (bport != 0)
+    {
+      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;
+
   plugin = GNUNET_malloc (sizeof (struct Plugin));
   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->nat_punched = nat_punched;
+  plugin->enable_nat_client = enable_nat_client;
+  plugin->enable_nat_server = enable_nat_server;
+  plugin->enable_upnp = enable_upnp;
   plugin->env = env;
   plugin->lsock = NULL;
   api = GNUNET_malloc (sizeof (struct GNUNET_TRANSPORT_PluginFunctions));
@@ -2457,81 +2865,109 @@ 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");
+         GNUNET_free_non_null(external_address);
+         GNUNET_free_non_null(internal_address);
+         GNUNET_free (api);
+         return NULL;
+       }
+      plugin->server = GNUNET_SERVER_create_with_sockets (NULL, NULL, 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;
-        }
+  GNUNET_SERVER_disconnect_notify (plugin->server,
+                                  &disconnect_notify,
+                                  plugin);    
+  GNUNET_OS_network_interfaces_list (&process_interfaces, plugin);
+
+  if ( (plugin->behind_nat == GNUNET_YES) &&
+       (plugin->enable_nat_server == GNUNET_YES) &&
+       (GNUNET_YES != tcp_transport_start_nat_server(plugin)) )
+    {
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                      _("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);
+      if (service != NULL)
+       GNUNET_SERVICE_stop (service);
+      else
+       GNUNET_SERVER_destroy (plugin->server);
+      GNUNET_free (api);
+      return NULL;
     }
 
-  if (allow_nat == GNUNET_YES)
+  if (enable_nat_client == GNUNET_YES)
     {
-      plugin->nat_wait_conns = GNUNET_CONTAINER_multihashmap_create(100);
-      GNUNET_assert(plugin->nat_wait_conns != NULL);
+      plugin->nat_wait_conns = GNUNET_CONTAINER_multihashmap_create(16);
+      GNUNET_assert (plugin->nat_wait_conns != NULL);
     }
 
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("TCP transport listening on port %llu\n"), bport);
+  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)
+  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_string (env->cfg,
+                                                          "transport-tcp", 
+                                                          "BINDTO", 
+                                                          &plugin->bind_address))
     {
-      GNUNET_OS_network_interfaces_list (&process_interfaces, plugin);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, 
+                      "tcp",
+                      _("Binding TCP plugin to specific address: `%s'\n"), 
+                      plugin->bind_address);
     }
 
-  plugin->hostname_dns = GNUNET_RESOLVER_hostname_resolve (env->sched,
-                                                           env->cfg,
+  plugin->hostname_dns = GNUNET_RESOLVER_hostname_resolve (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))
+  if (plugin->external_address != NULL) 
     {
-      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);
+      plugin->ext_dns = GNUNET_RESOLVER_ip_get (env->cfg,
+                                               plugin->external_address,
+                                               AF_INET,
+                                               GNUNET_TIME_UNIT_MINUTES,
+                                               &process_external_ip,
+                                               plugin);
     }
-
   return api;
 }
 
@@ -2546,7 +2982,13 @@ libgnunet_plugin_transport_tcp_done (void *cls)
   struct Plugin *plugin = api->cls;
   struct Session *session;
   struct LocalAddrList *lal;
+  struct TCPProbeContext *tcp_probe;
 
+  if (plugin->ext_dns != NULL)
+    {
+      GNUNET_RESOLVER_request_cancel (plugin->ext_dns);
+      plugin->ext_dns = NULL;
+    }
   while (NULL != (session = plugin->sessions))
     disconnect_session (session);
   if (NULL != plugin->hostname_dns)
@@ -2554,21 +2996,38 @@ libgnunet_plugin_transport_tcp_done (void *cls)
       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);
+      if (lal->nat != NULL)
+       GNUNET_NAT_unregister (lal->nat);
+      GNUNET_free_non_null (lal->external_nat_address);
       GNUNET_free (lal);
     }
+  while (NULL != (tcp_probe = plugin->probe_head))
+    {
+      GNUNET_CONTAINER_DLL_remove (plugin->probe_head,
+                                  plugin->probe_tail,
+                                  tcp_probe);
+      GNUNET_CONNECTION_destroy (tcp_probe->sock, GNUNET_NO);
+      GNUNET_free (tcp_probe);
+    }
 
-  if (plugin->behind_nat == GNUNET_YES)
+  if ((plugin->behind_nat == GNUNET_YES) &&
+      (plugin->enable_nat_server == GNUNET_YES))
     {
-      if (0 != PLIBC_KILL (plugin->server_pid, SIGTERM))
+      if (0 != GNUNET_OS_process_kill (plugin->server_proc, SIGTERM))
         GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "kill");
-      GNUNET_OS_process_wait (plugin->server_pid);
+      GNUNET_OS_process_wait (plugin->server_proc);
+      GNUNET_OS_process_close (plugin->server_proc);
+      plugin->server_proc = NULL;
     }
   GNUNET_free_non_null(plugin->bind_address);
   GNUNET_free (plugin);