android: Recreate the TUN device without DNS when reestablishing IKE_SAs

This enables DNS resolution while reestablishing if the VPN gateway pushed
DNS servers to the client that are only reachable via VPN.

diff --git a/src/frontends/android/jni/libandroidbridge/backend/android_service.c b/src/frontends/android/jni/libandroidbridge/backend/android_service.c
index 113056532eb4c9b5ff1c79494eaca161daafca20..73738c22ed78a0adf8ea456269bdb1867c1c6484 100644 (file)
--- a/src/frontends/android/jni/libandroidbridge/backend/android_service.c
+++ b/src/frontends/android/jni/libandroidbridge/backend/android_service.c
@@ -349,6 +349,36 @@ static bool setup_tun_device(private_android_service_t *this,
        return TRUE;
 }
 
+/**
+ * Setup a new TUN device based on the existing one, but without DNS server.
+ */
+static bool setup_tun_device_without_dns(private_android_service_t *this)
+{
+       vpnservice_builder_t *builder;
+       int tunfd;
+
+       DBG1(DBG_DMN, "setting up TUN device without DNS");
+
+       builder = charonservice->get_vpnservice_builder(charonservice);
+
+       tunfd = builder->establish_no_dns(builder);
+       if (tunfd == -1)
+       {
+               return FALSE;
+       }
+
+       this->lock->write_lock(this->lock);
+       if (this->tunfd > 0)
+       {       /* close previously opened TUN device, this should always be the case */
+               close(this->tunfd);
+       }
+       this->tunfd = tunfd;
+       this->lock->unlock(this->lock);
+
+       DBG1(DBG_DMN, "successfully created TUN device without DNS");
+       return TRUE;
+}
+
 /**
  * Close the current tun device
  */
@@ -479,6 +509,14 @@ METHOD(listener_t, ike_reestablish_pre, bool,
                this->lock->write_lock(this->lock);
                this->use_dns_proxy = TRUE;
                this->lock->unlock(this->lock);
+               /* if DNS servers are installed that are only reachable through the VPN
+                * the DNS proxy doesn't help, so uninstall DNS servers */
+               if (!setup_tun_device_without_dns(this))
+               {
+                       DBG1(DBG_DMN, "failed to setup TUN device without DNS");
+                       charonservice->update_status(charonservice,
+                                                                                CHARONSERVICE_GENERIC_ERROR);
+               }
        }
        return TRUE;
 }