1 files changed, 316 insertions, 0 deletions

diff --git a/src/service/nat/gnunet-service-nat_externalip.c b/src/service/nat/gnunet-service-nat_externalip.c
new file mode 100644
index 000000000..c2625be2d
--- /dev/null
+++ b/src/service/nat/gnunet-service-nat_externalip.c
@@ -0,0 +1,316 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2009, 2015, 2016, 2017 GNUnet e.V.
+
+     GNUnet is free software: you can redistribute it and/or modify it
+     under the terms of the GNU Affero General Public License as published
+     by the Free Software Foundation, either version 3 of the License,
+     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
+     Affero General Public License for more details.
+
+     You should have received a copy of the GNU Affero General Public License
+     along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+     SPDX-License-Identifier: AGPL3.0-or-later
+ */
+/**
+ * Code to figure out what our external IPv4 address(es) might
+ * be (external IPv4s are what is seen on the rest of the Internet).
+ *
+ * This can be implemented using different methods, and we allow
+ * the main service to be notified about changes to what we believe
+ * is our external IPv4 address.
+ *
+ * Note that this is explicitly only about NATed systems; if one
+ * of our network interfaces has a global IP address this does
+ * not count as "external".
+ *
+ * @file nat/gnunet-service-nat_externalip.c
+ * @brief Functions for monitoring external IPv4 addresses
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <math.h>
+#include "gnunet_util_lib.h"
+#include "gnunet_protocols.h"
+#include "gnunet_signatures.h"
+#include "gnunet_statistics_service.h"
+#include "gnunet_resolver_service.h"
+#include "gnunet_nat_service.h"
+#include "gnunet-service-nat.h"
+#include "gnunet-service-nat_externalip.h"
+#include "gnunet-service-nat_stun.h"
+#include "gnunet-service-nat_mini.h"
+#include "gnunet-service-nat_helper.h"
+#include "nat.h"
+#include <gcrypt.h>
+
+
+/**
+ * How long do we wait until we re-try running `external-ip` if the
+ * command failed to terminate nicely?
+ */
+#define EXTERN_IP_RETRY_TIMEOUT GNUNET_TIME_relative_multiply ( \
+    GNUNET_TIME_UNIT_MINUTES, 15)
+
+/**
+ * How long do we wait until we re-try running `external-ip` if the
+ * command failed (but terminated)?
+ */
+#define EXTERN_IP_RETRY_FAILURE GNUNET_TIME_relative_multiply ( \
+    GNUNET_TIME_UNIT_MINUTES, 30)
+
+/**
+ * How long do we wait until we re-try running `external-ip` if the
+ * command succeeded?
+ */
+#define EXTERN_IP_RETRY_SUCCESS GNUNET_TIME_relative_multiply ( \
+    GNUNET_TIME_UNIT_MINUTES, 5)
+
+
+/**
+ * Handle to monitor for external IP changes.
+ */
+struct GN_ExternalIPMonitor
+{
+  /**
+   * Kept in DLL.
+   */
+  struct GN_ExternalIPMonitor *next;
+
+  /**
+   * Kept in DLL.
+   */
+  struct GN_ExternalIPMonitor *prev;
+
+  /**
+   * Function to call when we believe our external IPv4 address changed.
+   */
+  GN_NotifyExternalIPv4Change cb;
+
+  /**
+   * Closure for @e cb.
+   */
+  void *cb_cls;
+};
+
+
+/**
+ * List of monitors, kept in DLL.
+ */
+static struct GN_ExternalIPMonitor *mon_head;
+
+/**
+ * List of monitors, kept in DLL.
+ */
+static struct GN_ExternalIPMonitor *mon_tail;
+
+/**
+ * Task run to obtain our external IP (if #enable_upnp is set
+ * and if we find we have a NATed IP address).
+ */
+static struct GNUNET_SCHEDULER_Task *probe_external_ip_task;
+
+/**
+ * Handle to our operation to run `external-ip`.
+ */
+static struct GNUNET_NAT_ExternalHandle *probe_external_ip_op;
+
+/**
+ * What is our external IP address as claimed by `external-ip`?
+ * 0 for unknown.
+ */
+static struct in_addr mini_external_ipv4;
+
+
+/**
+ * Tell relevant clients about a change in our external
+ * IPv4 address.
+ *
+ * @param add #GNUNET_YES to add, #GNUNET_NO to remove
+ * @param v4 the external address that changed
+ */
+static void
+notify_monitors_external_ipv4_change (int add,
+                                      const struct in_addr *v4)
+{
+  for (struct GN_ExternalIPMonitor *mon = mon_head;
+       NULL != mon;
+       mon = mon->next)
+    mon->cb (mon->cb_cls,
+             v4,
+             add);
+}
+
+
+/**
+ * Task used to run `external-ip` to get our external IPv4
+ * address and pass it to NATed clients if possible.
+ *
+ * @param cls NULL
+ */
+static void
+run_external_ip (void *cls);
+
+
+/**
+ * We learn our current external IP address.  If it changed,
+ * notify all of our applicable clients. Also re-schedule
+ * #run_external_ip with an appropriate timeout.
+ *
+ * @param cls NULL
+ * @param addr the address, NULL on errors
+ * @param result #GNUNET_NAT_ERROR_SUCCESS on success, otherwise the specific error code
+ */
+static void
+handle_external_ip (void *cls,
+                    const struct in_addr *addr,
+                    enum GNUNET_NAT_StatusCode result)
+{
+  char buf[INET_ADDRSTRLEN];
+
+  probe_external_ip_op = NULL;
+  GNUNET_SCHEDULER_cancel (probe_external_ip_task);
+  probe_external_ip_task
+    = GNUNET_SCHEDULER_add_delayed ((NULL == addr)
+                                    ? EXTERN_IP_RETRY_FAILURE
+                                    : EXTERN_IP_RETRY_SUCCESS,
+                                    &run_external_ip,
+                                    NULL);
+  switch (result)
+  {
+  case GNUNET_NAT_ERROR_SUCCESS:
+    GNUNET_assert (NULL != addr);
+    if (addr->s_addr == mini_external_ipv4.s_addr)
+      return;   /* not change */
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Our external IP is now %s\n",
+                inet_ntop (AF_INET,
+                           addr,
+                           buf,
+                           sizeof(buf)));
+    if (0 != mini_external_ipv4.s_addr)
+      notify_monitors_external_ipv4_change (GNUNET_NO,
+                                            &mini_external_ipv4);
+    mini_external_ipv4 = *addr;
+    notify_monitors_external_ipv4_change (GNUNET_YES,
+                                          &mini_external_ipv4);
+    break;
+
+  default:
+    if (0 != mini_external_ipv4.s_addr)
+      notify_monitors_external_ipv4_change (GNUNET_NO,
+                                            &mini_external_ipv4);
+    mini_external_ipv4.s_addr = 0;
+    break;
+  }
+}
+
+
+/**
+ * Task used to run `external-ip` to get our external IPv4
+ * address and pass it to NATed clients if possible.
+ *
+ * @param cls NULL
+ */
+static void
+run_external_ip (void *cls)
+{
+  probe_external_ip_task
+    = GNUNET_SCHEDULER_add_delayed (EXTERN_IP_RETRY_TIMEOUT,
+                                    &run_external_ip,
+                                    NULL);
+  if (NULL != probe_external_ip_op)
+  {
+    GNUNET_NAT_mini_get_external_ipv4_cancel_ (probe_external_ip_op);
+    probe_external_ip_op = NULL;
+  }
+  probe_external_ip_op
+    = GNUNET_NAT_mini_get_external_ipv4_ (&handle_external_ip,
+                                          NULL);
+}
+
+
+/**
+ * We have changed our opinion about being NATed in the first
+ * place. Adapt our probing.
+ *
+ * @param have_nat #GNUNET_YES if we believe we are behind NAT
+ */
+void
+GN_nat_status_changed (int have_nat)
+{
+  if (GNUNET_YES != enable_upnp)
+    return;
+  if ((GNUNET_YES == have_nat) &&
+      (NULL == probe_external_ip_task) &&
+      (NULL == probe_external_ip_op))
+  {
+    probe_external_ip_task
+      = GNUNET_SCHEDULER_add_now (&run_external_ip,
+                                  NULL);
+    return;
+  }
+  if (GNUNET_NO == have_nat)
+  {
+    if (NULL != probe_external_ip_task)
+    {
+      GNUNET_SCHEDULER_cancel (probe_external_ip_task);
+      probe_external_ip_task = NULL;
+    }
+    if (NULL != probe_external_ip_op)
+    {
+      GNUNET_NAT_mini_get_external_ipv4_cancel_ (probe_external_ip_op);
+      probe_external_ip_op = NULL;
+    }
+  }
+}
+
+
+/**
+ * Start monitoring external IPv4 addresses.
+ *
+ * @param cb function to call on changes
+ * @param cb_cls closure for @a cb
+ * @return handle to cancel
+ */
+struct GN_ExternalIPMonitor *
+GN_external_ipv4_monitor_start (GN_NotifyExternalIPv4Change cb,
+                                void *cb_cls)
+{
+  struct GN_ExternalIPMonitor *mon;
+
+  mon = GNUNET_new (struct GN_ExternalIPMonitor);
+  mon->cb = cb;
+  mon->cb_cls = cb_cls;
+  GNUNET_CONTAINER_DLL_insert (mon_head,
+                               mon_tail,
+                               mon);
+  if (0 != mini_external_ipv4.s_addr)
+    cb (cb_cls,
+        &mini_external_ipv4,
+        GNUNET_YES);
+  return mon;
+}
+
+
+/**
+ * Stop calling monitor.
+ *
+ * @param mon monitor to call
+ */
+void
+GN_external_ipv4_monitor_stop (struct GN_ExternalIPMonitor *mon)
+{
+  GNUNET_CONTAINER_DLL_remove (mon_head,
+                               mon_tail,
+                               mon);
+  GNUNET_free (mon);
+}
+
+
+/* end of gnunet-service-nat_externalip.c */