Add support for register-dns through interactive service

The call to the service returns promptly after delegating the job to a thread, before the task is completed. In the thread, "net stop dnscache", "net start dnscache", "ipconfig /flushdns" and "ipconfig /register-dns" are executed in that order.

Parallel execution of these commands is prevented by a lock that is common to all connections started by the service.

Note: "net stop .." is used instead of "sc stop.." as the latter can return before the service has fully stopped (in STOP_PENDING state), causing the subsequent start to fail.

---
 include/openvpn-msg.h         |    3 +-
 src/openvpn/tun.c             |   35 ++++++++-
 src/openvpnserv/interactive.c |  156 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 192 insertions(+), 2 deletions(-)

index 7470512..4c13acf 100644
@@ -37,7 +37,8 @@ typedef enum {
   msg_del_nbt_cfg,
   msg_flush_neighbors,
   msg_add_block_dns,
-  msg_del_block_dns
+  msg_del_block_dns,
+  msg_register_dns
 } message_type_t;
 
 typedef struct {

index eaeb6cc..dd9bdaf 100644
@@ -5101,10 +5101,43 @@ fork_dhcp_action (struct tuntap *tt)
     }
 }
 
+static void
+register_dns_service (const struct tuntap *tt)
+{
+  DWORD len;
+  HANDLE msg_channel = tt->options.msg_channel;
+  ack_message_t ack;
+  struct gc_arena gc = gc_new ();
+
+  message_header_t rdns = { msg_register_dns, sizeof(message_header_t), 0 };
+
+  if (!WriteFile (msg_channel, &rdns, sizeof (rdns), &len, NULL) ||
+      !ReadFile (msg_channel, &ack, sizeof (ack), &len, NULL))
+    {
+      msg (M_WARN, "Register_dns: could not talk to service: %s [status=0x%lx]",
+           strerror_win32 (GetLastError (), &gc), GetLastError ());
+    }
+
+  else if (ack.error_number != NO_ERROR)
+    {
+      msg (M_WARN, "Register_dns failed using service: %s [status=0x%x]",
+           strerror_win32 (ack.error_number, &gc), ack.error_number);
+    }
+
+  else
+      msg (M_INFO, "Register_dns request sent to the service");
+
+  gc_free (&gc);
+}
+
 void
 fork_register_dns_action (struct tuntap *tt)
 {
-  if (tt && tt->options.register_dns)
+  if (tt && tt->options.register_dns && tt->options.msg_channel)
+    {
+       register_dns_service (tt);
+    }
+  else if (tt && tt->options.register_dns)
     {
       struct gc_arena gc = gc_new ();
       struct buffer cmd = alloc_buf_gc (256, &gc);

1.7.10.4

Hi,

Motivated by the discussion on "forgotten" patches, here is a reminder for review time..

http://thread.gmane.org/gmane.network.openvpn.devel/11354

Thanks,

Selva

ACK. Thanks a lot, and sorry for the delay in reviewing.

I've stared at the code, and it looks good to me (very clean code, if I may say so :-) ) - the openvpn code is definitely good, the iservice code "looks reasonable", though I might be missing some windows intricacies.

Compile-tested on my mingw test environment, but have not run it yet - I'm going to be lazy and wait for Samuli's build snapshot.

Your patch has been applied to the master branch.

commit 3e42a558103e4e3f45ed28ccb761cefed20e8247 (master)

Author: Selva Nair
Date:   Thu Mar 10 23:47:26 2016 -0500

     Add support for register-dns through interactive service

     Signed-off-by: Selva Nair <[email protected]...>
     Acked-by: Gert Doering <[email protected]...>
     Message-Id: <[email protected]...>
     URL: http://article.gmane.org/gmane.network.openvpn.devel/11354
     Signed-off-by: Gert Doering <[email protected]...>

--
kind regards,

Gert Doering