Ticket #721: a813e1789d76.patch

src/adapter.c

@@ -222 +222 @@
     Adapter->MediaStateAlwaysConnected = FALSE;
     Adapter->LogicalMediaState = FALSE;
     Adapter->AllowNonAdmin = FALSE;
+    // source check can not be set in the registry yet. This has to be set each
+    // time the adapter is opened.
+    Adapter->m_source_check = TRUE;
     //
     // Open the registry for this adapter to read advanced
     // configuration parameters stored by the INF file.

src/adapter.h

@@ -4 +4 @@
  *
  *  This code was inspired by the CIPE-Win32 driver by Damion K. Wilson.
  * 
+ *  Copyright (C) 2016 Noel Kuntze <noel@familie-kuntze.de>
  *  This source code is Copyright (C) 2002-2014 OpenVPN Technologies, Inc.,
  *  and is released under the GPL version 2 (see below).
  *
@@ -251 +252 @@
   BOOLEAN m_CalledAdapterFreeResources;
   BOOLEAN m_RegisteredAdapterShutdownHandler;
 
+   // This variable is initialised as TRUE. If it is set to FALSE, the adapter does
+   // not check the source IP field of the ARP requests it receives on the adapter.
+  BOOLEAN m_source_check;
+
 } TAP_ADAPTER_CONTEXT, *PTAP_ADAPTER_CONTEXT;
 
 FORCEINLINE

src/device.c

@@ -4 +4 @@
  *
  *  This code was inspired by the CIPE-Win32 driver by Damion K. Wilson.
  *
+ *  Copyright (C) 2016 Noel Kuntze <noel@familie-kuntze.de>
  *  This source code is Copyright (C) 2002-2014 OpenVPN Technologies, Inc.,
  *  and is released under the GPL version 2 (see below).
  *
@@ -692 +693 @@
             }
         }
         break;
-
+    case TAP_WIN_IOCTL_CONFIG_SET_SRC_CHECK:
+        {
+            if (inBufLength >= sizeof(ULONG))
+            {
+                adapter->m_source_check = (BOOLEAN) ((PULONG) (Irp->AssociatedIrp.SystemBuffer))[0];
+                Irp->IoStatus.Information = 1;
+            }
+            else
+            {
+                NOTE_ERROR();
+                Irp->IoStatus.Status = ntStatus = STATUS_INVALID_PARAMETER;
+            }
+        }
+        break;
     default:
 
         //

src/tap-windows.h

@@ -4 +4 @@
  *
  *  This code was inspired by the CIPE-Win32 driver by Damion K. Wilson.
  *
+ *  Copyright (C) 2016 Noel Kuntze <noel@familie-kuntze.de>
  *  This source code is Copyright (C) 2002-2014 OpenVPN Technologies, Inc.,
  *  and is released under the GPL version 2 (see below).
  *
@@ -49 +50 @@
 
 /* obsoletes TAP_WIN_IOCTL_CONFIG_POINT_TO_POINT */
 #define TAP_WIN_IOCTL_CONFIG_TUN            TAP_WIN_CONTROL_CODE (10, METHOD_BUFFERED)
-
+#define TAP_WIN_IOCTL_CONFIG_SET_SRC_CHECK  TAP_WIN_CONTROL_CODE (11, METHOD_BUFFERED)
 /*
  * =================
  * Registry keys

src/txpath.c

@@ -4 +4 @@
  *
  *  This code was inspired by the CIPE-Win32 driver by Damion K. Wilson.
  * 
+ *  Copyright (C) 2016 Noel Kuntze <noel@familie-kuntze.de>
  *  This source code is Copyright (C) 2002-2014 OpenVPN Technologies, Inc.,
  *  and is released under the GPL version 2 (see below).
  *
@@ -216 +217 @@
     //-----------------------------------------------
     // Is this the kind of packet we are looking for?
     //-----------------------------------------------
+    BOOLEAN source_check = FALSE;
+    if (Adapter->m_source_check)
+    {
+        source_check = (src->m_ARP_IP_Source == adapter_ip);
+    }
+    else
+    {
+        source_check = TRUE;
+    }
     if (src->m_Proto == htons (NDIS_ETH_TYPE_ARP)
         && MAC_EQUAL (src->m_MAC_Source, Adapter->PermanentAddress)
         && MAC_EQUAL (src->m_ARP_MAC_Source, Adapter->PermanentAddress)
@@ -225 +235 @@
         && src->m_MAC_AddressSize == sizeof (MACADDR)
         && src->m_PROTO_AddressType == htons (NDIS_ETH_TYPE_IPV4)
         && src->m_PROTO_AddressSize == sizeof (IPADDR)
-        && src->m_ARP_IP_Source == adapter_ip
+        && source_check
         && (src->m_ARP_IP_Destination & ip_netmask) == ip_network
         && src->m_ARP_IP_Destination != adapter_ip)
     {