Create a TUN device via VpnService.Builder once the CHILD_SA is established

diff --git a/src/frontends/android/jni/libandroidbridge/backend/android_service.c b/src/frontends/android/jni/libandroidbridge/backend/android_service.c
index 5c18924..691d5fc 100644 (file)
--- a/src/frontends/android/jni/libandroidbridge/backend/android_service.c
+++ b/src/frontends/android/jni/libandroidbridge/backend/android_service.c
@@ -17,13 +17,17 @@
 
 #include "android_service.h"
 #include "../charonservice.h"
+#include "../vpnservice_builder.h"
 
 #include <daemon.h>
 #include <library.h>
 #include <processing/jobs/callback_job.h>
+#include <threading/rwlock.h>
 
 typedef struct private_android_service_t private_android_service_t;
 
+#define TUN_DEFAULT_MTU 1400
+
 /**
  * private data of Android service
  */
@@ -54,8 +58,72 @@ struct private_android_service_t {
         */
        char *username;
 
+       /**
+        * lock to safely access the TUN device fd
+        */
+       rwlock_t *lock;
+
+       /**
+        * TUN device file descriptor
+        */
+       int tunfd;
+
 };
 
+/**
+ * Setup a new TUN device for the supplied SAs.
+ * Additional information such as DNS servers are gathered in appropriate
+ * listeners asynchronously.  To be sure every required bit of information is
+ * available this should be called after the CHILD_SA has been established.
+ */
+static bool setup_tun_device(private_android_service_t *this,
+                                                        ike_sa_t *ike_sa, child_sa_t *child_sa)
+{
+       vpnservice_builder_t *builder;
+       int tunfd;
+
+       DBG1(DBG_DMN, "setting up TUN device for CHILD_SA %s{%u}",
+                child_sa->get_name(child_sa), child_sa->get_reqid(child_sa));
+
+       builder = charonservice->get_vpnservice_builder(charonservice);
+       if (!builder->set_mtu(builder, TUN_DEFAULT_MTU))
+       {
+               return FALSE;
+       }
+
+       tunfd = builder->establish(builder);
+       if (tunfd == -1)
+       {
+               return FALSE;
+       }
+
+       this->lock->write_lock(this->lock);
+       this->tunfd = tunfd;
+       this->lock->unlock(this->lock);
+
+       DBG1(DBG_DMN, "successfully created TUN device");
+       return TRUE;
+}
+
+/**
+ * Close the current tun device
+ */
+static void close_tun_device(private_android_service_t *this)
+{
+       int tunfd;
+
+       this->lock->write_lock(this->lock);
+       if (this->tunfd < 0)
+       {       /* already closed (or never created) */
+               this->lock->unlock(this->lock);
+               return;
+       }
+       tunfd = this->tunfd;
+       this->tunfd = -1;
+       this->lock->unlock(this->lock);
+       close(tunfd);
+}
+
 METHOD(listener_t, child_updown, bool,
        private_android_service_t *this, ike_sa_t *ike_sa, child_sa_t *child_sa,
        bool up)
@@ -67,11 +135,20 @@ METHOD(listener_t, child_updown, bool,
                        /* disable the hooks registered to catch initiation failures */
                        this->public.listener.ike_updown = NULL;
                        this->public.listener.ike_state_change = NULL;
+                       if (!setup_tun_device(this, ike_sa, child_sa))
+                       {
+                               DBG1(DBG_DMN, "failed to setup TUN device");
+                               charonservice->update_status(charonservice,
+                                                                                        CHARONSERVICE_GENERIC_ERROR);
+                               return FALSE;
+
+                       }
                        charonservice->update_status(charonservice,
                                                                                 CHARONSERVICE_CHILD_STATE_UP);
                }
                else
                {
+                       close_tun_device(this);
                        charonservice->update_status(charonservice,
                                                                                 CHARONSERVICE_CHILD_STATE_DOWN);
                        return FALSE;
@@ -230,6 +307,9 @@ METHOD(android_service_t, destroy, void,
        private_android_service_t *this)
 {
        charon->bus->remove_listener(charon->bus, &this->public.listener);
+       /* make sure the tun device is actually closed */
+       close_tun_device(this);
+       this->lock->destroy(this->lock);
        free(this->local_address);
        free(this->username);
        free(this->gateway);
@@ -255,9 +335,11 @@ android_service_t *android_service_create(char *local_address, char *gateway,
                        },
                        .destroy = _destroy,
                },
+               .lock = rwlock_create(RWLOCK_TYPE_DEFAULT),
                .local_address = local_address,
                .username = username,
                .gateway = gateway,
+               .tunfd = -1,
        );
 
        charon->bus->add_listener(charon->bus, &this->public.listener);