Re: [Openvpn-devel] More BSD TUN info.

[Janne Johansson]

> >Yes, but since BSD wont let you choose if you want it or not, and the
> chance of changing Linux-TUN-drivers now is slim, I guess it has to be
> the application that takes care of this. I'll try to make a patch and
> test it, and send you the diff later.
> 
> Some thoughts:
> 
> * probably the best place to add/remove the AF_INET is by calling some
> routine in the main event loop in openvpn.c, conditional on --remote-is-bsd.
> 
> * add and remove u_int_32 by manipulating struct buffer (see buf_prepend and
> buf_advance in particular).
> 
> * remember that when you add a new buffer prepend item, you must modify the
> appropriate struct frame which will contain the MTU parms, so that
> everything gets sized right.  For an example, see
> crypto_adjust_frame_parameters().

I have made an attempt but I must warn you, I'm no guru on pointers
and stuff, so I'd like you to check my calls to see that I'm on the
right track please:
I will test this asap and tell you if it works.

diff -ru openvpn-1.0.3/openvpn.c new_openvpn-1.0.3/openvpn.c
--- openvpn-1.0.3/openvpn.c     Fri Mar 29 01:43:12 2002
+++ new_openvpn-1.0.3/openvpn.c Thu Apr  4 12:09:32 2002
@@ -91,6 +91,8 @@
   "                : 8 -- show all debug info\n"
   "--gremlin       : Simulate dropped & corrupted packets + network outages\n"
   "                  to test robustness of protocol (for debugging only).\n"
+  "--remote-bsd    : If the remote system is using BSD tun devices that add\n"
+  "                  protocol info on each packet sent.\n"
 #ifdef USE_LZO
   "--comp-lzo      : Use fast LZO compression -- may add up to 1 byte per\n"
   "                  packet for uncompressible data.\n"
@@ -210,6 +212,7 @@
   o->verbosity = 1;
   o->bind_local = true;
   o->tun_mtu = DEFAULT_TUN_MTU;
+  o->remotebsd = false;
 #ifdef USE_LZO
   o->comp_lzo_adaptive = true;
 #endif
@@ -262,6 +265,7 @@
   SHOW_INT (nice);
   SHOW_INT (verbosity);
   SHOW_BOOL (gremlin);
+  SHOW_BOOL (remotebsd);
 
 #ifdef USE_LZO
   SHOW_BOOL (comp_lzo);
@@ -426,6 +430,11 @@
 
 static void frame_finalize(struct frame *frame, const struct options *options)
 {
+  if (options->remotebsd)
+    {
+      frame->extra_frame += 4;
+    }
+
   if (options->tun_mtu_defined)
     {
       frame->mtu = options->tun_mtu;
@@ -872,6 +881,11 @@
              check_status (buf.len, "read from tun");
              if (buf.len > 0)
                {
+                 if (options->remotebsd)
+                   {
+                     buf_advance(&buf, sizeof(u_int32_t));
+                   }
+
 #ifdef USE_LZO
                  if (options->comp_lzo)
                    lzo_compress (&buf, lzo_compress_buf, &lzo_compwork, 
&frame, current);
@@ -905,6 +919,13 @@
          if (FD_ISSET (td, &writes))
            {
              int size;
+
+             if (options->remotebsd)
+               {
+                 u_int32_t af = htonl(AF_INET);
+                 buf_write_prepend(&to_tun, &af ,sizeof (u_int32_t));
+               }
+
              ASSERT (to_tun.len > 0 && to_tun.len <= MAX_RW_SIZE_TUN(&frame));
              size = write (td, BPTR (&to_tun), BLEN (&to_tun));
              check_status (size, "write to tun");
@@ -1155,6 +1176,10 @@
        {
          options.bind_local = false;
        }
+      else if (streq (p1, "--remote-bsd"))
+       {
+         options.remotebsd = true;
+       }
 #ifdef USE_LZO
       else if (streq (p1, "--comp-lzo"))
        {
diff -ru openvpn-1.0.3/openvpn.h new_openvpn-1.0.3/openvpn.h
--- openvpn-1.0.3/openvpn.h     Sat Mar 30 03:24:00 2002
+++ new_openvpn-1.0.3/openvpn.h Thu Apr  4 11:16:46 2002
@@ -53,6 +53,7 @@
   int nice;
   int verbosity;
   bool gremlin;
+  bool remotebsd;
 
 #ifdef USE_LZO
   bool comp_lzo;

-- 
Janne Johansson
jan.johans...@biomatsys.com
BioMat Systems AB
Klarabergsg 37 3tr
111 21 Stockholm

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