-importing from gnunet-daemon-vpn to gnunet-service-vpn what can likely be re-used

2 files changed, 1349 insertions, 1 deletions

diff --git a/src/vpn/Makefile.am b/src/vpn/Makefile.am
index 1fb1dd3f6..380db4446 100644
--- a/src/vpn/Makefile.am
+++ b/src/vpn/Makefile.am
@@ -26,7 +26,7 @@ endif
 
 
 bin_PROGRAMS = \
-  gnunet-daemon-exit gnunet-daemon-vpn $(VPNBIN) $(HIJACKBIN)
+  gnunet-daemon-exit gnunet-daemon-vpn $(VPNBIN) gnunet-service-vpn
 
 
 gnunet_helper_vpn_SOURCES = \
@@ -43,6 +43,14 @@ gnunet_daemon_vpn_LDADD = \
   $(top_builddir)/src/dns/libgnunetdns.la \
   $(GN_LIBINTL)
 
+gnunet_service_vpn_SOURCES = \
+ gnunet-service-vpn.c 
+gnunet_service_vpn_LDADD = \
+  $(top_builddir)/src/statistics/libgnunetstatistics.la \
+  $(top_builddir)/src/util/libgnunetutil.la \
+  $(top_builddir)/src/mesh/libgnunetmesh.la \
+  $(GN_LIBINTL)
+
 gnunet_daemon_exit_SOURCES = \
  gnunet-daemon-exit.c 
 gnunet_daemon_exit_LDADD = \
diff --git a/src/vpn/gnunet-service-vpn.c b/src/vpn/gnunet-service-vpn.c
new file mode 100644
index 000000000..098d8b944
--- /dev/null
+++ b/src/vpn/gnunet-service-vpn.c
@@ -0,0 +1,1340 @@
+/*
+     This file is part of GNUnet.
+     (C) 2010, 2011, 2012 Christian Grothoff
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+
+/**
+ * @file vpn/gnunet-service-vpn.c
+ * @brief service that opens a virtual interface and allows its clients
+ *        to allocate IPs on the virtual interface and to then redirect
+ *        IP traffic received on those IPs via the GNUnet mesh 
+ * @author Philipp Toelke
+ */
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet-vpn-packet.h"
+#include "gnunet_common.h"
+#include "gnunet_protocols.h"
+#include "gnunet_applications.h"
+#include "gnunet_mesh_service.h"
+#include "gnunet_constants.h"
+
+
+
+struct map_entry
+{
+    /** The description of the service (used for service) */
+  GNUNET_HashCode desc;
+
+    /** The real address of the service (used for remote) */
+  char addrlen;
+  char addr[16];
+
+  struct GNUNET_MESH_Tunnel *tunnel;
+  uint16_t namelen;
+  char additional_ports[8192];
+
+  struct GNUNET_CONTAINER_HeapNode *heap_node;
+  GNUNET_HashCode hash;
+
+};
+
+
+struct remote_addr
+{
+  char addrlen;
+  unsigned char addr[16];
+  char proto;
+};
+
+
+struct tunnel_notify_queue
+{
+  struct tunnel_notify_queue *next;
+  struct tunnel_notify_queue *prev;
+  size_t len;
+  void *cls;
+};
+
+
+struct tunnel_state
+{
+  struct GNUNET_MESH_TransmitHandle *th;
+  struct tunnel_notify_queue *head, *tail;
+
+  int addrlen;
+};
+
+
+
+/**
+ * Configuration we use.
+ */
+static const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+/**
+ * Handle to the mesh service.
+ */
+static struct GNUNET_MESH_Handle *mesh_handle;
+
+/**
+ * FIXME
+ */
+static struct GNUNET_CONTAINER_MultiHashMap *hashmap;
+
+/**
+ * FIXME
+ */
+static struct GNUNET_CONTAINER_Heap *heap;
+
+/**
+ * The handle to the VPN helper process "gnunet-helper-vpn".
+ */
+static struct GNUNET_HELPER_Handle *helper_handle;
+
+/**
+ * Arguments to the exit helper.
+ */
+static char *vpn_argv[7];
+
+/**
+ * If there are at least this many address-mappings, old ones will be removed
+ */
+static unsigned long long max_mappings;
+
+
+/**
+ * @return the hash of the IP-Address if a mapping exists, NULL otherwise
+ */
+static GNUNET_HashCode *
+address6_mapping_exists (struct in6_addr *v6addr)
+{
+  unsigned char *addr = (unsigned char*) v6addr;
+  GNUNET_HashCode *key = GNUNET_malloc (sizeof (GNUNET_HashCode));
+  unsigned char *k = (unsigned char *) key;
+
+  memset (key, 0, sizeof (GNUNET_HashCode));
+  unsigned int i;
+
+  for (i = 0; i < 16; i++)
+    k[15 - i] = addr[i];
+
+  if (GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains (hashmap, key))
+    return key;
+  else
+  {
+    GNUNET_free (key);
+    return NULL;
+  }
+}
+
+/**
+ * @return the hash of the IP-Address if a mapping exists, NULL otherwise
+ */
+static GNUNET_HashCode *
+address4_mapping_exists (uint32_t addr)
+{
+  GNUNET_HashCode *key = GNUNET_malloc (sizeof (GNUNET_HashCode));
+
+  memset (key, 0, sizeof (GNUNET_HashCode));
+  unsigned char *c = (unsigned char *) &addr;
+  unsigned char *k = (unsigned char *) key;
+  unsigned int i;
+
+  for (i = 0; i < 4; i++)
+    k[3 - i] = c[i];
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "a4_m_e: getting with key %08x, addr is %08x, %d.%d.%d.%d\n",
+              *((uint32_t *) (key)), addr, c[0], c[1], c[2], c[3]);
+
+  if (GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains (hashmap, key))
+    return key;
+  else
+  {
+    GNUNET_free (key);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Mapping not found!\n");
+    return NULL;
+  }
+}
+
+
+static void *
+initialize_tunnel_state (int addrlen, struct GNUNET_MESH_TransmitHandle *th)
+{
+  struct tunnel_state *ts = GNUNET_malloc (sizeof *ts);
+
+  ts->addrlen = addrlen;
+  ts->th = th;
+  return ts;
+}
+
+
+static void
+send_icmp4_response (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  if ((tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN) != 0)
+    return;
+
+  struct ip_icmp *request = cls;
+
+  struct ip_icmp *response = alloca (ntohs (request->shdr.size));
+
+  GNUNET_assert (response != NULL);
+  memset (response, 0, ntohs (request->shdr.size));
+
+  response->shdr.size = request->shdr.size;
+  response->shdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
+
+  response->tun.flags = 0;
+  response->tun.type = htons (0x0800);
+
+  response->ip_hdr.hdr_lngth = 5;
+  response->ip_hdr.version = 4;
+  response->ip_hdr.proto = 0x01;
+  response->ip_hdr.dadr = request->ip_hdr.sadr;
+  response->ip_hdr.sadr = request->ip_hdr.dadr;
+  response->ip_hdr.tot_lngth = request->ip_hdr.tot_lngth;
+
+  response->ip_hdr.chks =
+      GNUNET_CRYPTO_crc16_n ((uint16_t *) & response->ip_hdr, 20);
+
+  response->icmp_hdr.code = 0;
+  response->icmp_hdr.type = 0x0;
+
+  /* Magic, more Magic! */
+  response->icmp_hdr.chks = request->icmp_hdr.chks + 0x8;
+
+  /* Copy the rest of the packet */
+  memcpy (response + 1, request + 1,
+          ntohs (request->shdr.size) - sizeof (struct ip_icmp));
+
+  (void) GNUNET_HELPER_send (helper_handle,
+                             &response->shdr,
+                             GNUNET_YES,
+                             NULL, NULL);
+  GNUNET_free (request);
+}
+
+
+static void
+send_icmp6_response (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  if ((tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN) != 0)
+    return;
+
+  struct ip6_icmp *request = cls;
+
+  struct ip6_icmp *response = alloca (ntohs (request->shdr.size));
+
+  GNUNET_assert (response != NULL);
+  memset (response, 0, ntohs (request->shdr.size));
+
+  response->shdr.size = request->shdr.size;
+  response->shdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
+
+  response->tun.flags = 0;
+  response->tun.type = htons (0x86dd);
+
+  response->ip6_hdr.hoplmt = 255;
+  response->ip6_hdr.paylgth = request->ip6_hdr.paylgth;
+  response->ip6_hdr.nxthdr = 0x3a;
+  response->ip6_hdr.version = 6;
+  memcpy (&response->ip6_hdr.sadr, &request->ip6_hdr.dadr, 16);
+  memcpy (&response->ip6_hdr.dadr, &request->ip6_hdr.sadr, 16);
+
+  response->icmp_hdr.code = 0;
+  response->icmp_hdr.type = 0x81;
+
+  /* Magic, more Magic! */
+  response->icmp_hdr.chks = request->icmp_hdr.chks - 0x1;
+
+  /* Copy the rest of the packet */
+  memcpy (response + 1, request + 1,
+          ntohs (request->shdr.size) - sizeof (struct ip6_icmp));
+
+  (void) GNUNET_HELPER_send (helper_handle,
+                             &response->shdr,
+                             GNUNET_YES,
+                             NULL, NULL);
+  GNUNET_free (request);
+}
+
+
+/**
+ * cls is the pointer to a GNUNET_MessageHeader that is
+ * followed by the service-descriptor and the packet that should be sent;
+ */
+static size_t
+send_pkt_to_peer_notify_callback (void *cls, size_t size, void *buf)
+{
+  struct GNUNET_MESH_Tunnel **tunnel = cls;
+
+  struct tunnel_state *ts = GNUNET_MESH_tunnel_get_data (*tunnel);
+
+  ts->th = NULL;
+
+  if (NULL != buf)
+  {
+    struct GNUNET_MessageHeader *hdr =
+        (struct GNUNET_MessageHeader *) (tunnel + 1);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "send_pkt_to_peer_notify_callback: buf = %x; size = %u;\n", buf,
+                size);
+    GNUNET_assert (size >= ntohs (hdr->size));
+    memcpy (buf, hdr, ntohs (hdr->size));
+    size = ntohs (hdr->size);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sent!\n");
+  }
+  else
+    size = 0;
+
+  if (NULL != ts->head)
+  {
+    struct tunnel_notify_queue *element = ts->head;
+
+    GNUNET_CONTAINER_DLL_remove (ts->head, ts->tail, element);
+
+    ts->th =
+        GNUNET_MESH_notify_transmit_ready (*tunnel, GNUNET_NO, 42,
+                                           GNUNET_TIME_relative_divide
+                                           (GNUNET_CONSTANTS_MAX_CORK_DELAY, 2),
+                                           (const struct GNUNET_PeerIdentity *)
+                                           NULL, element->len,
+                                           send_pkt_to_peer_notify_callback,
+                                           element->cls);
+
+    /* save the handle */
+    GNUNET_free (element);
+  }
+  GNUNET_free (cls);
+
+  return size;
+}
+
+
+static void
+send_pkt_to_peer (void *cls, const struct GNUNET_PeerIdentity *peer,
+                  const struct GNUNET_ATS_Information *atsi GNUNET_UNUSED)
+{
+  /* peer == NULL means that all peers in this request are connected */
+  if (peer == NULL)
+    return;
+  struct GNUNET_MESH_Tunnel **tunnel = cls;
+  struct GNUNET_MessageHeader *hdr =
+      (struct GNUNET_MessageHeader *) (tunnel + 1);
+
+  GNUNET_assert (NULL != tunnel);
+  GNUNET_assert (NULL != *tunnel);
+
+  struct tunnel_state *ts = GNUNET_MESH_tunnel_get_data (*tunnel);
+
+  if (NULL == ts->th)
+  {
+    ts->th =
+        GNUNET_MESH_notify_transmit_ready (*tunnel, GNUNET_NO, 42,
+                                           GNUNET_TIME_relative_divide
+                                           (GNUNET_CONSTANTS_MAX_CORK_DELAY, 2),
+                                           (const struct GNUNET_PeerIdentity *)
+                                           NULL, ntohs (hdr->size),
+                                           send_pkt_to_peer_notify_callback,
+                                           cls);
+  }
+  else
+  {
+    struct tunnel_notify_queue *element = GNUNET_malloc (sizeof *element);
+
+    element->cls = cls;
+    element->len = ntohs (hdr->size);
+
+    GNUNET_CONTAINER_DLL_insert_tail (ts->head, ts->tail, element);
+  }
+}
+
+
+
+
+/**
+ * Receive packets from the helper-process
+ */
+static void
+message_token (void *cls GNUNET_UNUSED, void *client GNUNET_UNUSED,
+               const struct GNUNET_MessageHeader *message)
+{
+  GNUNET_assert (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_HELPER);
+
+  struct tun_pkt *pkt_tun = (struct tun_pkt *) message;
+  GNUNET_HashCode *key;
+
+  /* ethertype is ipv6 */
+  if (ntohs (pkt_tun->tun.type) == 0x86dd)
+  {
+    struct ip6_pkt *pkt6 = (struct ip6_pkt *) message;
+
+    GNUNET_assert (pkt6->ip6_hdr.version == 6);
+    struct ip6_tcp *pkt6_tcp;
+    struct ip6_udp *pkt6_udp;
+    struct ip6_icmp *pkt6_icmp;
+
+    pkt6_udp = NULL;            /* make compiler happy */
+    switch (pkt6->ip6_hdr.nxthdr)
+    {
+    case IPPROTO_UDP:
+      pkt6_udp = (struct ip6_udp *) pkt6;
+      /* Send dns-packets to the service-dns */
+      /* fall through */
+    case IPPROTO_TCP:
+      pkt6_tcp = (struct ip6_tcp *) pkt6;
+
+      if ((key = address6_mapping_exists (&pkt6->ip6_hdr.dadr)) != NULL)
+      {
+        struct map_entry *me = GNUNET_CONTAINER_multihashmap_get (hashmap, key);
+
+        GNUNET_assert (me != NULL);
+        GNUNET_free (key);
+
+        size_t size =
+            sizeof (struct GNUNET_MESH_Tunnel *) +
+            sizeof (struct GNUNET_MessageHeader) + sizeof (GNUNET_HashCode) +
+            ntohs (pkt6->ip6_hdr.paylgth);
+
+        struct GNUNET_MESH_Tunnel **cls = GNUNET_malloc (size);
+        struct GNUNET_MessageHeader *hdr =
+            (struct GNUNET_MessageHeader *) (cls + 1);
+        GNUNET_HashCode *hc = (GNUNET_HashCode *) (hdr + 1);
+
+        hdr->size =
+            htons (sizeof (struct GNUNET_MessageHeader) +
+                   sizeof (GNUNET_HashCode) + ntohs (pkt6->ip6_hdr.paylgth));
+
+        GNUNET_MESH_ApplicationType app_type = 0;       /* fix compiler uninitialized warning... */
+
+        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "me->addrlen is %d\n",
+                    me->addrlen);
+        if (me->addrlen == 0)
+        {
+          /* This is a mapping to a gnunet-service */
+          *hc = me->desc;
+
+          if (me->tunnel == NULL && NULL != cls)
+          {
+            *cls =
+                GNUNET_MESH_tunnel_create (mesh_handle,
+                                           initialize_tunnel_state (16, NULL),
+                                           &send_pkt_to_peer, NULL, cls);
+
+            GNUNET_MESH_peer_request_connect_add (*cls,
+                                                  (struct GNUNET_PeerIdentity *)
+                                                  &me->desc);
+            me->tunnel = *cls;
+          }
+          else if (NULL != cls)
+          {
+            *cls = me->tunnel;
+            send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1, NULL);
+          }
+        }
+        else
+        {
+          /* This is a mapping to a "real" address */
+          struct remote_addr *s = (struct remote_addr *) hc;
+
+          s->addrlen = me->addrlen;
+          memcpy (s->addr, me->addr, me->addrlen);
+          s->proto = pkt6->ip6_hdr.nxthdr;
+          if (s->proto == IPPROTO_UDP)
+          {
+            hdr->type = htons (GNUNET_MESSAGE_TYPE_VPN_REMOTE_UDP);
+            memcpy (hc + 1, &pkt6_udp->udp_hdr, ntohs (pkt6_udp->udp_hdr.len));
+            app_type = GNUNET_APPLICATION_TYPE_INTERNET_UDP_GATEWAY;
+          }
+          else if (s->proto == IPPROTO_TCP)
+          {
+            hdr->type = htons (GNUNET_MESSAGE_TYPE_VPN_REMOTE_TCP);
+            memcpy (hc + 1, &pkt6_tcp->tcp_hdr, ntohs (pkt6->ip6_hdr.paylgth));
+            app_type = GNUNET_APPLICATION_TYPE_INTERNET_TCP_GATEWAY;
+          }
+          else
+          {
+            GNUNET_assert (0);
+          }
+          if (me->tunnel == NULL && NULL != cls)
+          {
+            *cls =
+                GNUNET_MESH_tunnel_create (mesh_handle,
+                                           initialize_tunnel_state (16, NULL),
+                                           &send_pkt_to_peer, NULL, cls);
+
+            GNUNET_MESH_peer_request_connect_by_type (*cls, app_type);
+            me->tunnel = *cls;
+          }
+          else if (NULL != cls)
+          {
+            *cls = me->tunnel;
+            send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1, NULL);
+          }
+        }
+      }
+      else
+      {
+        char pbuf[INET6_ADDRSTRLEN];
+        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                    "Packet to %s, which has no mapping\n",
+                    inet_ntop (AF_INET6,
+                               &pkt6->ip6_hdr.dadr,
+                               pbuf,
+                               sizeof (pbuf)));
+      }
+      break;
+    case 0x3a:
+      /* ICMPv6 */
+      pkt6_icmp = (struct ip6_icmp *) pkt6;
+      /* If this packet is an icmp-echo-request and a mapping exists, answer */
+      if (pkt6_icmp->icmp_hdr.type == 0x80 &&
+          (key = address6_mapping_exists (&pkt6->ip6_hdr.dadr)) != NULL)
+      {
+        GNUNET_free (key);
+        pkt6_icmp = GNUNET_malloc (ntohs (pkt6->shdr.size));
+        memcpy (pkt6_icmp, pkt6, ntohs (pkt6->shdr.size));
+        GNUNET_SCHEDULER_add_now (&send_icmp6_response, pkt6_icmp);
+      }
+      break;
+    }
+  }
+  /* ethertype is ipv4 */
+  else if (ntohs (pkt_tun->tun.type) == 0x0800)
+  {
+    struct ip_pkt *pkt = (struct ip_pkt *) message;
+    //struct ip_udp *udp = (struct ip_udp *) message;
+    struct ip_tcp *pkt_tcp;
+    struct ip_udp *pkt_udp;
+    struct ip_icmp *pkt_icmp;
+
+    GNUNET_assert (pkt->ip_hdr.version == 4);
+
+    {
+      uint32_t dadr = pkt->ip_hdr.dadr.s_addr;
+      unsigned char *c = (unsigned char *) &dadr;
+
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Packet to %d.%d.%d.%d, proto %x\n",
+                  c[0], c[1], c[2], c[3], pkt->ip_hdr.proto);
+      switch (pkt->ip_hdr.proto)
+      {
+      case IPPROTO_TCP:
+      case IPPROTO_UDP:
+        pkt_tcp = (struct ip_tcp *) pkt;
+        pkt_udp = (struct ip_udp *) pkt;
+
+        if ((key = address4_mapping_exists (dadr)) != NULL)
+        {
+          struct map_entry *me =
+              GNUNET_CONTAINER_multihashmap_get (hashmap, key);
+          GNUNET_assert (me != NULL);
+          GNUNET_free (key);
+
+          size_t size =
+              sizeof (struct GNUNET_MESH_Tunnel *) +
+              sizeof (struct GNUNET_MessageHeader) + sizeof (GNUNET_HashCode) +
+              ntohs (pkt->ip_hdr.tot_lngth) - 4 * pkt->ip_hdr.hdr_lngth;
+
+          struct GNUNET_MESH_Tunnel **cls = GNUNET_malloc (size);
+          struct GNUNET_MessageHeader *hdr =
+              (struct GNUNET_MessageHeader *) (cls + 1);
+          GNUNET_HashCode *hc = (GNUNET_HashCode *) (hdr + 1);
+
+          hdr->size =
+              htons (sizeof (struct GNUNET_MessageHeader) +
+                     sizeof (GNUNET_HashCode) + ntohs (pkt->ip_hdr.tot_lngth) -
+                     4 * pkt->ip_hdr.hdr_lngth);
+
+          GNUNET_MESH_ApplicationType app_type = 0; /* make compiler happy */
+
+          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "me->addrlen is %d\n",
+                      me->addrlen);
+          if (me->addrlen == 0)
+          {
+            /* This is a mapping to a gnunet-service */
+            *hc = me->desc;
+
+            if (me->tunnel == NULL && NULL != cls)
+            {
+              *cls =
+                  GNUNET_MESH_tunnel_create (mesh_handle,
+                                             initialize_tunnel_state (4, NULL),
+                                             send_pkt_to_peer, NULL, cls);
+              GNUNET_MESH_peer_request_connect_add (*cls,
+                                                    (struct GNUNET_PeerIdentity
+                                                     *) &me->desc);
+              me->tunnel = *cls;
+            }
+            else if (NULL != cls)
+            {
+              *cls = me->tunnel;
+              send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1, NULL);
+            }
+          }
+          else
+          {
+            /* This is a mapping to a "real" address */
+            struct remote_addr *s = (struct remote_addr *) hc;
+
+            s->addrlen = me->addrlen;
+            memcpy (s->addr, me->addr, me->addrlen);
+            s->proto = pkt->ip_hdr.proto;
+            if (s->proto == IPPROTO_UDP)
+            {
+              hdr->type = htons (GNUNET_MESSAGE_TYPE_VPN_REMOTE_UDP);
+              memcpy (hc + 1, &pkt_udp->udp_hdr, ntohs (pkt_udp->udp_hdr.len));
+              app_type = GNUNET_APPLICATION_TYPE_INTERNET_UDP_GATEWAY;
+            }
+            else if (s->proto == IPPROTO_TCP)
+            {
+              hdr->type = htons (GNUNET_MESSAGE_TYPE_VPN_REMOTE_TCP);
+              memcpy (hc + 1, &pkt_tcp->tcp_hdr,
+                      ntohs (pkt->ip_hdr.tot_lngth) -
+                      4 * pkt->ip_hdr.hdr_lngth);
+              app_type = GNUNET_APPLICATION_TYPE_INTERNET_TCP_GATEWAY;
+            }
+            else
+              GNUNET_assert (0);
+            if (me->tunnel == NULL && NULL != cls)
+            {
+              *cls =
+                  GNUNET_MESH_tunnel_create (mesh_handle,
+                                             initialize_tunnel_state (4, NULL),
+                                             send_pkt_to_peer, NULL, cls);
+
+              GNUNET_MESH_peer_request_connect_by_type (*cls, app_type);
+              me->tunnel = *cls;
+            }
+            else if (NULL != cls)
+            {
+              *cls = me->tunnel;
+              send_pkt_to_peer (cls, (struct GNUNET_PeerIdentity *) 1, NULL);
+            }
+          }
+        }
+        else
+        {
+          GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                      "Packet to %x which has no mapping\n", dadr);
+        }
+        break;
+      case 0x01:
+        /* ICMP */
+        pkt_icmp = (struct ip_icmp *) pkt;
+        if (pkt_icmp->icmp_hdr.type == 0x8 &&
+            (key = address4_mapping_exists (dadr)) != NULL)
+        {
+          GNUNET_free (key);
+          pkt_icmp = GNUNET_malloc (ntohs (pkt->shdr.size));
+          memcpy (pkt_icmp, pkt, ntohs (pkt->shdr.size));
+          GNUNET_SCHEDULER_add_now (&send_icmp4_response, pkt_icmp);
+        }
+        break;
+      }
+    }
+  }
+}
+
+
+
+
+
+/**
+ * Create a new Address from an answer-packet
+ */
+static void
+new_ip6addr (struct in6_addr *v6addr,
+             const GNUNET_HashCode * peer,
+             const GNUNET_HashCode * service_desc)
+{                               /* {{{ */
+  unsigned char *buf = (unsigned char*) v6addr;
+  char *ipv6addr;
+  unsigned long long ipv6prefix;
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV6ADDR",
+                                                        &ipv6addr));
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONFIGURATION_get_value_number (cfg, "vpn",
+                                                        "IPV6PREFIX",
+                                                        &ipv6prefix));
+  GNUNET_assert (ipv6prefix < 127);
+  ipv6prefix = (ipv6prefix + 7) / 8;
+
+  inet_pton (AF_INET6, ipv6addr, buf);
+  GNUNET_free (ipv6addr);
+
+  int peer_length = 16 - ipv6prefix - 6;
+
+  if (peer_length <= 0)
+    peer_length = 0;
+
+  int service_length = 16 - ipv6prefix - peer_length;
+
+  if (service_length <= 0)
+    service_length = 0;
+
+  memcpy (buf + ipv6prefix, service_desc, service_length);
+  memcpy (buf + ipv6prefix + service_length, peer, peer_length);
+}
+
+/*}}}*/
+
+
+/**
+ * Create a new Address from an answer-packet
+ */
+static void
+new_ip6addr_remote (struct in6_addr *v6addr,
+                    unsigned char *addr, char addrlen)
+{                               /* {{{ */
+  unsigned char *buf = (unsigned char*) v6addr;
+  char *ipv6addr;
+  unsigned long long ipv6prefix;
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV6ADDR",
+                                                        &ipv6addr));
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONFIGURATION_get_value_number (cfg, "vpn",
+                                                        "IPV6PREFIX",
+                                                        &ipv6prefix));
+  GNUNET_assert (ipv6prefix < 127);
+  ipv6prefix = (ipv6prefix + 7) / 8;
+
+  inet_pton (AF_INET6, ipv6addr, buf);
+  GNUNET_free (ipv6addr);
+
+  int local_length = 16 - ipv6prefix;
+
+  memcpy (buf + ipv6prefix, addr, GNUNET_MIN (addrlen, local_length));
+}
+
+/*}}}*/
+
+/**
+ * Create a new Address from an answer-packet
+ */
+static void
+new_ip4addr_remote (unsigned char *buf, unsigned char *addr, char addrlen)
+{                               /* {{{ */
+  char *ipv4addr;
+  char *ipv4mask;
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV4ADDR",
+                                                        &ipv4addr));
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV4MASK",
+                                                        &ipv4mask));
+  uint32_t mask;
+
+  inet_pton (AF_INET, ipv4addr, buf);
+  int r = inet_pton (AF_INET, ipv4mask, &mask);
+
+  mask = htonl (mask);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "inet_pton: %d; %m; mask: %08x\n", r,
+              mask);
+
+  GNUNET_free (ipv4addr);
+
+  int c;
+
+  if (mask)
+  {
+    mask = (mask ^ (mask - 1)) >> 1;
+    for (c = 0; mask; c++)
+    {
+      mask >>= 1;
+    }
+  }
+  else
+  {
+    c = CHAR_BIT * sizeof (mask);
+  }
+
+  c = 32 - c;
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "The mask %s has %d leading 1s.\n",
+              ipv4mask, c);
+
+  GNUNET_free (ipv4mask);
+
+  if (c % 8 == 0)
+    c = c / 8;
+  else
+    GNUNET_assert (0);
+
+  memcpy (buf + c, addr, GNUNET_MIN (addrlen, 4 - c));
+}
+
+/*}}}*/
+
+
+
+/**
+ * FIXME: document.
+ */ 
+static int
+receive_udp_back (void *cls GNUNET_UNUSED, struct GNUNET_MESH_Tunnel *tunnel,
+                  void **tunnel_ctx, const struct GNUNET_PeerIdentity *sender,
+                  const struct GNUNET_MessageHeader *message,
+                  const struct GNUNET_ATS_Information *atsi GNUNET_UNUSED)
+{
+  GNUNET_HashCode *desc = (GNUNET_HashCode *) (message + 1);
+  struct remote_addr *s = (struct remote_addr *) desc;
+  struct udp_pkt *pkt = (struct udp_pkt *) (desc + 1);
+  const struct GNUNET_PeerIdentity *other = sender;
+  struct tunnel_state *ts = *tunnel_ctx;
+
+  if (16 == ts->addrlen)
+  {
+    size_t size =
+        sizeof (struct ip6_udp) + ntohs (pkt->len) - 1 -
+        sizeof (struct udp_pkt);
+
+    struct ip6_udp *pkt6 = alloca (size);
+
+    GNUNET_assert (pkt6 != NULL);
+
+    if (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_SERVICE_UDP_BACK)
+      new_ip6addr (&pkt6->ip6_hdr.sadr, &other->hashPubKey, desc);
+    else
+      new_ip6addr_remote (&pkt6->ip6_hdr.sadr, s->addr, s->addrlen);
+
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Relaying calc:%d gnu:%d udp:%d bytes!\n", size,
+                ntohs (message->size), ntohs (pkt->len));
+
+    pkt6->shdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
+    pkt6->shdr.size = htons (size);
+
+    pkt6->tun.flags = 0;
+    pkt6->tun.type = htons (0x86dd);
+
+    pkt6->ip6_hdr.version = 6;
+    pkt6->ip6_hdr.tclass_h = 0;
+    pkt6->ip6_hdr.tclass_l = 0;
+    pkt6->ip6_hdr.flowlbl = 0;
+    pkt6->ip6_hdr.paylgth = pkt->len;
+    pkt6->ip6_hdr.nxthdr = IPPROTO_UDP;
+    pkt6->ip6_hdr.hoplmt = 0xff;
+
+    {
+      char *ipv6addr;
+
+      GNUNET_assert (GNUNET_OK ==
+                     GNUNET_CONFIGURATION_get_value_string (cfg, "vpn",
+                                                            "IPV6ADDR",
+                                                            &ipv6addr));
+      inet_pton (AF_INET6, ipv6addr, &pkt6->ip6_hdr.dadr);
+      GNUNET_free (ipv6addr);
+    }
+    memcpy (&pkt6->udp_hdr, pkt, ntohs (pkt->len));
+
+    GNUNET_HashCode *key = address6_mapping_exists (&pkt6->ip6_hdr.sadr);
+
+    GNUNET_assert (key != NULL);
+
+    struct map_entry *me = GNUNET_CONTAINER_multihashmap_get (hashmap, key);
+
+    GNUNET_CONTAINER_heap_update_cost (heap, me->heap_node,
+                                       GNUNET_TIME_absolute_get ().abs_value);
+
+    GNUNET_free (key);
+
+    GNUNET_assert (me != NULL);
+
+    pkt6->udp_hdr.crc = 0;
+    uint32_t sum = 0;
+
+    sum =
+        GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & pkt6->ip6_hdr.sadr, 16);
+    sum =
+        GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & pkt6->ip6_hdr.dadr, 16);
+    uint32_t tmp = (pkt6->udp_hdr.len & 0xffff);
+
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & tmp, 4);
+    tmp = htons (((pkt6->ip6_hdr.nxthdr & 0x00ff)));
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & tmp, 4);
+
+    sum =
+        GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & pkt6->udp_hdr,
+                                   ntohs (pkt->len));
+    pkt6->udp_hdr.crc = GNUNET_CRYPTO_crc16_finish (sum);
+    
+    (void) GNUNET_HELPER_send (helper_handle,
+                               &pkt6->shdr,
+                               GNUNET_YES,
+                               NULL, NULL);
+  }
+  else
+  {
+    size_t size =
+        sizeof (struct ip_udp) + ntohs (pkt->len) - 1 - sizeof (struct udp_pkt);
+
+    struct ip_udp *pkt4 = alloca (size);
+
+    GNUNET_assert (pkt4 != NULL);
+
+    GNUNET_assert (ntohs (message->type) ==
+                   GNUNET_MESSAGE_TYPE_VPN_REMOTE_UDP_BACK);
+    uint32_t sadr;
+
+    new_ip4addr_remote ((unsigned char *) &sadr, s->addr, s->addrlen);
+    pkt4->ip_hdr.sadr.s_addr = sadr;
+
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Relaying calc:%d gnu:%d udp:%d bytes!\n", size,
+                ntohs (message->size), ntohs (pkt->len));
+
+    pkt4->shdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
+    pkt4->shdr.size = htons (size);
+
+    pkt4->tun.flags = 0;
+    pkt4->tun.type = htons (0x0800);
+
+    pkt4->ip_hdr.version = 4;
+    pkt4->ip_hdr.hdr_lngth = 5;
+    pkt4->ip_hdr.diff_serv = 0;
+    pkt4->ip_hdr.tot_lngth = htons (20 + ntohs (pkt->len));
+    pkt4->ip_hdr.ident = 0;
+    pkt4->ip_hdr.flags = 0;
+    pkt4->ip_hdr.frag_off = 0;
+    pkt4->ip_hdr.ttl = 255;
+    pkt4->ip_hdr.proto = IPPROTO_UDP;
+    pkt4->ip_hdr.chks = 0;      /* Will be calculated later */
+
+    {
+      char *ipv4addr;
+      uint32_t dadr;
+
+      GNUNET_assert (GNUNET_OK ==
+                     GNUNET_CONFIGURATION_get_value_string (cfg, "vpn",
+                                                            "IPV4ADDR",
+                                                            &ipv4addr));
+      inet_pton (AF_INET, ipv4addr, &dadr);
+      GNUNET_free (ipv4addr);
+      pkt4->ip_hdr.dadr.s_addr = dadr;
+    }
+    memcpy (&pkt4->udp_hdr, pkt, ntohs (pkt->len));
+
+    GNUNET_HashCode *key = address4_mapping_exists (pkt4->ip_hdr.sadr.s_addr);
+
+    GNUNET_assert (key != NULL);
+
+    struct map_entry *me = GNUNET_CONTAINER_multihashmap_get (hashmap, key);
+
+    GNUNET_CONTAINER_heap_update_cost (heap, me->heap_node,
+                                       GNUNET_TIME_absolute_get ().abs_value);
+
+    GNUNET_free (key);
+
+    GNUNET_assert (me != NULL);
+
+    pkt4->udp_hdr.crc = 0;      /* Optional for IPv4 */
+
+    pkt4->ip_hdr.chks =
+        GNUNET_CRYPTO_crc16_n ((uint16_t *) & pkt4->ip_hdr, 5 * 4);
+
+    (void) GNUNET_HELPER_send (helper_handle,
+                               &pkt4->shdr,
+                               GNUNET_YES,
+                               NULL, NULL);
+  }
+
+  return GNUNET_OK;
+}
+
+
+/**
+ * FIXME: document.
+ */ 
+static int
+receive_tcp_back (void *cls GNUNET_UNUSED, struct GNUNET_MESH_Tunnel *tunnel,
+                  void **tunnel_ctx,
+                  const struct GNUNET_PeerIdentity *sender GNUNET_UNUSED,
+                  const struct GNUNET_MessageHeader *message,
+                  const struct GNUNET_ATS_Information *atsi GNUNET_UNUSED)
+{
+  GNUNET_HashCode *desc = (GNUNET_HashCode *) (message + 1);
+  struct remote_addr *s = (struct remote_addr *) desc;
+  struct tcp_pkt *pkt = (struct tcp_pkt *) (desc + 1);
+  const struct GNUNET_PeerIdentity *other = sender;
+  struct tunnel_state *ts = *tunnel_ctx;
+
+  size_t pktlen =
+      ntohs (message->size) - sizeof (struct GNUNET_MessageHeader) -
+      sizeof (GNUNET_HashCode);
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Received TCP-Packet back, addrlen = %d\n", s->addrlen);
+
+  if (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_SERVICE_TCP_BACK ||
+      ts->addrlen == 16)
+  {
+    size_t size = pktlen + sizeof (struct ip6_tcp) - 1;
+
+    struct ip6_tcp *pkt6 = alloca (size);
+
+    memset (pkt6, 0, size);
+
+    GNUNET_assert (pkt6 != NULL);
+
+    if (ntohs (message->type) == GNUNET_MESSAGE_TYPE_VPN_SERVICE_TCP_BACK)
+      new_ip6addr (&pkt6->ip6_hdr.sadr, &other->hashPubKey, desc);
+    else
+      new_ip6addr_remote (&pkt6->ip6_hdr.sadr, s->addr, s->addrlen);
+
+    pkt6->shdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
+    pkt6->shdr.size = htons (size);
+
+    pkt6->tun.flags = 0;
+    pkt6->tun.type = htons (0x86dd);
+
+    pkt6->ip6_hdr.version = 6;
+    pkt6->ip6_hdr.tclass_h = 0;
+    pkt6->ip6_hdr.tclass_l = 0;
+    pkt6->ip6_hdr.flowlbl = 0;
+    pkt6->ip6_hdr.paylgth = htons (pktlen);
+    pkt6->ip6_hdr.nxthdr = IPPROTO_TCP;
+    pkt6->ip6_hdr.hoplmt = 0xff;
+
+    {
+      char *ipv6addr;
+
+      GNUNET_assert (GNUNET_OK ==
+                     GNUNET_CONFIGURATION_get_value_string (cfg, "vpn",
+                                                            "IPV6ADDR",
+                                                            &ipv6addr));
+      inet_pton (AF_INET6, ipv6addr, &pkt6->ip6_hdr.dadr);
+      GNUNET_free (ipv6addr);
+    }
+    memcpy (&pkt6->tcp_hdr, pkt, pktlen);
+
+    GNUNET_HashCode *key = address6_mapping_exists (&pkt6->ip6_hdr.sadr);
+
+    GNUNET_assert (key != NULL);
+
+    struct map_entry *me = GNUNET_CONTAINER_multihashmap_get (hashmap, key);
+
+    GNUNET_CONTAINER_heap_update_cost (heap, me->heap_node,
+                                       GNUNET_TIME_absolute_get ().abs_value);
+
+    GNUNET_free (key);
+
+    GNUNET_assert (me != NULL);
+
+    pkt6->tcp_hdr.crc = 0;
+    uint32_t sum = 0;
+    uint32_t tmp;
+
+    sum =
+        GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & pkt6->ip6_hdr.sadr, 16);
+    sum =
+        GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & pkt6->ip6_hdr.dadr, 16);
+    tmp = htonl (pktlen);
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & tmp, 4);
+    tmp = htonl (((pkt6->ip6_hdr.nxthdr & 0x000000ff)));
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & tmp, 4);
+
+    sum =
+        GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & pkt6->tcp_hdr,
+                                   ntohs (pkt6->ip6_hdr.paylgth));
+    pkt6->tcp_hdr.crc = GNUNET_CRYPTO_crc16_finish (sum);
+
+    (void) GNUNET_HELPER_send (helper_handle,
+                               &pkt6->shdr,
+                               GNUNET_YES,
+                               NULL, NULL);
+  }
+  else
+  {
+    size_t size = pktlen + sizeof (struct ip_tcp) - 1;
+
+    struct ip_tcp *pkt4 = alloca (size);
+
+    GNUNET_assert (pkt4 != NULL);
+    memset (pkt4, 0, size);
+
+    GNUNET_assert (ntohs (message->type) ==
+                   GNUNET_MESSAGE_TYPE_VPN_REMOTE_TCP_BACK);
+    uint32_t sadr;
+
+    new_ip4addr_remote ((unsigned char *) &sadr, s->addr, s->addrlen);
+    pkt4->ip_hdr.sadr.s_addr = sadr;
+
+    pkt4->shdr.type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
+    pkt4->shdr.size = htons (size);
+
+    pkt4->tun.flags = 0;
+    pkt4->tun.type = htons (0x0800);
+
+    pkt4->ip_hdr.version = 4;
+    pkt4->ip_hdr.hdr_lngth = 5;
+    pkt4->ip_hdr.diff_serv = 0;
+    pkt4->ip_hdr.tot_lngth = htons (20 + pktlen);
+    pkt4->ip_hdr.ident = 0;
+    pkt4->ip_hdr.flags = 0;
+    pkt4->ip_hdr.frag_off = 0;
+    pkt4->ip_hdr.ttl = 255;
+    pkt4->ip_hdr.proto = IPPROTO_TCP;
+    pkt4->ip_hdr.chks = 0;      /* Will be calculated later */
+
+    {
+      char *ipv4addr;
+      uint32_t dadr;
+
+      GNUNET_assert (GNUNET_OK ==
+                     GNUNET_CONFIGURATION_get_value_string (cfg, "vpn",
+                                                            "IPV4ADDR",
+                                                            &ipv4addr));
+      inet_pton (AF_INET, ipv4addr, &dadr);
+      GNUNET_free (ipv4addr);
+      pkt4->ip_hdr.dadr.s_addr = dadr;
+    }
+
+    memcpy (&pkt4->tcp_hdr, pkt, pktlen);
+
+    GNUNET_HashCode *key = address4_mapping_exists (pkt4->ip_hdr.sadr.s_addr);
+
+    GNUNET_assert (key != NULL);
+
+    struct map_entry *me = GNUNET_CONTAINER_multihashmap_get (hashmap, key);
+
+    GNUNET_CONTAINER_heap_update_cost (heap, me->heap_node,
+                                       GNUNET_TIME_absolute_get ().abs_value);
+
+    GNUNET_free (key);
+
+    GNUNET_assert (me != NULL);
+    pkt4->tcp_hdr.crc = 0;
+    uint32_t sum = 0;
+    uint32_t tmp;
+
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) &pkt4->ip_hdr.sadr, 4);
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) &pkt4->ip_hdr.dadr, 4);
+
+    tmp = (0x06 << 16) | (0xffff & pktlen);     // 0x06 for TCP?
+
+    tmp = htonl (tmp);
+
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & tmp, 4);
+
+    sum = GNUNET_CRYPTO_crc16_step (sum, (uint16_t *) & pkt4->tcp_hdr, pktlen);
+    pkt4->tcp_hdr.crc = GNUNET_CRYPTO_crc16_finish (sum);
+
+    pkt4->ip_hdr.chks =
+        GNUNET_CRYPTO_crc16_n ((uint16_t *) & pkt4->ip_hdr, 5 * 4);
+
+    (void) GNUNET_HELPER_send (helper_handle,
+                               &pkt4->shdr,
+                               GNUNET_YES,
+                               NULL, NULL);
+
+  }
+
+  return GNUNET_OK;
+}
+
+
+/**
+ * FIXME: document.
+ */ 
+static void *
+new_tunnel (void *cls, struct GNUNET_MESH_Tunnel *tunnel,
+            const struct GNUNET_PeerIdentity *initiator,
+            const struct GNUNET_ATS_Information *atsi)
+{
+  /* Why should anyone open an inbound tunnel to vpn? */
+  GNUNET_break (0);
+  return NULL;
+}
+
+
+/**
+ * FIXME: document.
+ */ 
+static void
+tunnel_cleaner (void *cls, const struct GNUNET_MESH_Tunnel *tunnel, void *tunnel_ctx)
+{
+  /* Why should anyone open an inbound tunnel to vpn? */
+  /* FIXME: is this not also called for outbound tunnels that go down!? */
+  GNUNET_break (0);
+}
+
+
+/**
+ * Function scheduled as very last function, cleans up after us
+ */
+static void
+cleanup (void *cls GNUNET_UNUSED,
+         const struct GNUNET_SCHEDULER_TaskContext *tskctx)
+{
+  unsigned int i;
+
+  if (mesh_handle != NULL)
+  {
+    GNUNET_MESH_disconnect (mesh_handle);
+    mesh_handle = NULL;
+  }
+  if (helper_handle != NULL)
+  {
+    GNUNET_HELPER_stop (helper_handle);
+    helper_handle = NULL;
+  }
+  for (i=0;i<5;i++)
+    GNUNET_free_non_null (vpn_argv[i]);
+}
+
+
+/**
+ * Main function that will be run by the scheduler.
+ *
+ * @param cls closure
+ * @param server the initialized server
+ * @param cfg_ configuration
+ */
+static void
+run (void *cls,
+     struct GNUNET_SERVER_Handle *server,
+     const struct GNUNET_CONFIGURATION_Handle *cfg_)
+{
+  static const struct GNUNET_MESH_MessageHandler handlers[] = {
+    {receive_udp_back, GNUNET_MESSAGE_TYPE_VPN_SERVICE_UDP_BACK, 0},
+    {receive_tcp_back, GNUNET_MESSAGE_TYPE_VPN_SERVICE_TCP_BACK, 0},
+    {receive_udp_back, GNUNET_MESSAGE_TYPE_VPN_REMOTE_UDP_BACK, 0},
+    {receive_tcp_back, GNUNET_MESSAGE_TYPE_VPN_REMOTE_TCP_BACK, 0},
+    {NULL, 0, 0}
+  };
+  static const GNUNET_MESH_ApplicationType types[] = {
+    GNUNET_APPLICATION_TYPE_END
+  };
+  char *ifname;
+  char *ipv6addr;
+  char *ipv6prefix_s;
+  char *ipv4addr;
+  char *ipv4mask;
+  struct in_addr v4;
+  struct in6_addr v6;
+  unsigned long long ipv6prefix;
+
+  cfg = cfg_;
+  hashmap = GNUNET_CONTAINER_multihashmap_create (65536);
+  heap = GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_number (cfg, "vpn", "MAX_MAPPING",
+                                             &max_mappings))
+    max_mappings = 200;
+
+  vpn_argv[0] = GNUNET_strdup ("vpn-gnunet");
+  if (GNUNET_SYSERR ==
+      GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IFNAME", &ifname))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "No entry 'IFNAME' in configuration!\n");
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  vpn_argv[1] = ifname;
+  if ( (GNUNET_SYSERR ==
+        GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV6ADDR",
+                                               &ipv6addr) ||
+        (1 != inet_pton (AF_INET6, ipv6addr, &v6))) )
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "No valid entry 'IPV6ADDR' in configuration!\n");
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  vpn_argv[2] = ipv6addr;
+  if (GNUNET_SYSERR ==
+      GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV6PREFIX",
+                                             &ipv6prefix_s))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "No entry 'IPV6PREFIX' in configuration!\n");
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  vpn_argv[3] = ipv6prefix_s;
+  if ( (GNUNET_OK !=
+        GNUNET_CONFIGURATION_get_value_number (cfg, "vpn",
+                                               "IPV6PREFIX",
+                                               &ipv6prefix)) ||
+       (ipv6prefix >= 127) )
+  {
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+
+  if ( (GNUNET_SYSERR ==
+        GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV4ADDR",
+                                               &ipv4addr) ||
+        (1 != inet_pton (AF_INET, ipv4addr, &v4))) )
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "No valid entry for 'IPV4ADDR' in configuration!\n");
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  vpn_argv[4] = ipv4addr;
+  if ( (GNUNET_SYSERR ==
+        GNUNET_CONFIGURATION_get_value_string (cfg, "vpn", "IPV4MASK",
+                                               &ipv4mask) ||
+        (1 != inet_pton (AF_INET, ipv4mask, &v4))) )
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "No valid entry 'IPV4MASK' in configuration!\n");
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  vpn_argv[5] = ipv4mask;
+  vpn_argv[6] = NULL;
+
+  mesh_handle =
+    GNUNET_MESH_connect (cfg_, 42 /* queue length */, NULL, 
+                         &new_tunnel, 
+                         &tunnel_cleaner, 
+                         handlers,
+                         types);
+  helper_handle = GNUNET_HELPER_start ("gnunet-helper-vpn", vpn_argv,
+                                       &message_token, NULL);
+  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls);
+}
+
+
+/**
+ * The main function of the VPN service.
+ *
+ * @param argc number of arguments from the command line
+ * @param argv command line arguments
+ * @return 0 ok, 1 on error
+ */
+int
+main (int argc, char *const *argv)
+{
+  return (GNUNET_OK ==
+          GNUNET_SERVICE_run (argc, argv, "vpn", 
+                              GNUNET_SERVICE_OPTION_NONE,
+                              &run, NULL)) ? 0 : 1;
+}
+
+/* end of gnunet-service-vpn.c */