[Openvpn-devel] [PATCH] Keep pre-existing tun/tap devices around on *BSD

[Gert Doering]

This amends commit 62c613d46dc49 to check whether a named tun/tap
device ("--dev tunX" instead of "--dev tun") exists before OpenVPN
started - if yes, keep around at program end.  If no, destroy.

Also has a spelling fix, and changes clear_tuntap() to be "static"
(only ever called from within tun.c).

Tested on FreeBSD 7.4, FreeBSD 9.0, NetBSD 5.1, OpenBSD 4.9

Signed-off-by: Gert Doering <g...@greenie.muc.de>
Acked-by: Eric Crist <ecr...@secure-computing.net>
---
 src/openvpn/tun.c |   22 +++++++++++++++++-----
 src/openvpn/tun.h |    4 +++-
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
index 6218b73..ed67261 100644
--- a/src/openvpn/tun.c
+++ b/src/openvpn/tun.c
@@ -890,7 +890,7 @@ do_ifconfig (struct tuntap *tt,
 #elif defined(TARGET_OPENBSD)

       /*
-       * On OpenBSD, tun interfaces are persistant if created with
+       * On OpenBSD, tun interfaces are persistent if created with
        * "ifconfig tunX create", and auto-destroyed if created by
        * opening "/dev/tunX" (so we just use the /dev/tunX)
        */
@@ -1235,7 +1235,7 @@ do_ifconfig (struct tuntap *tt,
   gc_free (&gc);
 }

-void
+static void
 clear_tuntap (struct tuntap *tuntap)
 {
   CLEAR (*tuntap);
@@ -1344,6 +1344,13 @@ open_tun_generic (const char *dev, const char *dev_type, 
const char *dev_node,

       if (!dynamic_opened)
        {
+         /* has named device existed before? if so, don't destroy at end */
+         if ( if_nametoindex( dev ) > 0 )
+           {
+             msg (M_INFO, "TUN/TAP device %s exists previously, keep at 
program end", dev );
+             tt->persistent_if = true;
+           }
+
          if ((tt->fd = open (tunname, O_RDWR)) < 0)
            msg (M_ERR, "Cannot open TUN/TAP dev %s", tunname);
        }
@@ -2030,7 +2037,7 @@ close_tun (struct tuntap* tt)
 {
   /* only *TAP* devices need destroying, tun devices auto-self-destruct
    */
-  if (tt && tt->type == DEV_TYPE_TUN )
+  if (tt && (tt->type == DEV_TYPE_TUN || tt->persistent_if ) )
     {
       close_tun_generic (tt);
       free(tt);
@@ -2165,7 +2172,7 @@ close_tun (struct tuntap *tt)
 {
   /* only tun devices need destroying, tap devices auto-self-destruct
    */
-  if (tt && tt->type != DEV_TYPE_TUN )
+  if (tt && ( tt->type != DEV_TYPE_TUN || tt->persistent_if ) )
     {
       close_tun_generic (tt);
       free(tt);
@@ -2303,7 +2310,12 @@ open_tun (const char *dev, const char *dev_type, const 
char *dev_node, struct tu
 void
 close_tun (struct tuntap *tt)
 {
-  if (tt)
+  if (tt && tt->persistent_if )                /* keep pre-existing if around 
*/
+    {
+      close_tun_generic (tt);
+      free (tt);
+    }
+  else if (tt)                         /* close and destroy */
     {
       struct gc_arena gc = gc_new ();
       struct argv argv;
diff --git a/src/openvpn/tun.h b/src/openvpn/tun.h
index 9bd990f..8622bf8 100644
--- a/src/openvpn/tun.h
+++ b/src/openvpn/tun.h
@@ -137,6 +137,8 @@ struct tuntap

   bool ipv6;

+  bool persistent_if;          /* if existed before, keep on program end */
+
   struct tuntap_options options; /* options set on command line */

   char *actual_name; /* actual name of TUN/TAP dev, usually including unit 
number */
@@ -201,7 +203,7 @@ tuntap_defined (const struct tuntap *tt)
  * Function prototypes
  */

-void clear_tuntap (struct tuntap *tuntap);
+static void clear_tuntap (struct tuntap *tuntap);

 void open_tun (const char *dev, const char *dev_type, const char *dev_node,
               struct tuntap *tt);
-- 
1.7.3.5