Tap driver basically builds in VS2012... fork of tap-windows from OpenVPN (compatible license).

vsprojects/TapDriver/instance.c

@@ -0,0 +1,241 @@
+/*
+ *  TAP-Windows -- A kernel driver to provide virtual tap
+ *                 device functionality on Windows.
+ *
+ *  This code was inspired by the CIPE-Win32 driver by Damion K. Wilson.
+ *
+ *  This source code is Copyright (C) 2002-2010 OpenVPN Technologies, Inc.,
+ *  and is released under the GPL version 2 (see below).
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#define INSTANCE_KEY(a) ((PVOID)((a)->m_Extension.m_TapDevice))
+
+#define N_INSTANCE_BUCKETS 256
+
+typedef struct _INSTANCE {
+  struct _INSTANCE *next;
+  TapAdapterPointer m_Adapter;
+} INSTANCE;
+
+typedef struct {
+  INSTANCE *list;
+  MUTEX lock;
+} INSTANCE_BUCKET;
+
+typedef struct {
+  INSTANCE_BUCKET buckets[N_INSTANCE_BUCKETS];
+} INSTANCE_HASH;
+
+INSTANCE_HASH *g_InstanceHash = NULL;
+
+// must return a hash >= 0 and < N_INSTANCE_BUCKETS
+int
+InstanceHashValue (PVOID addr)
+{
+  UCHAR *p = (UCHAR *) &addr;
+
+  if (sizeof (addr) == 4)
+    return p[0] ^ p[1] ^ p[2] ^ p[3];
+  else if (sizeof (addr) == 8)
+    return p[0] ^ p[1] ^ p[2] ^ p[3] ^ p[4] ^ p[5] ^ p[6] ^ p[7];
+  else
+    {
+      MYASSERT (0);
+    }
+}
+
+BOOLEAN
+InitInstanceList (VOID)
+{
+  MYASSERT (g_InstanceHash == NULL);
+  g_InstanceHash = MemAlloc (sizeof (INSTANCE_HASH), TRUE);
+  if (g_InstanceHash)
+    {
+      int i;
+      for (i = 0; i < N_INSTANCE_BUCKETS; ++i)
+	INIT_MUTEX (&g_InstanceHash->buckets[i].lock);
+      return TRUE;
+    }
+  else
+    return FALSE;
+}
+
+int
+NInstances (VOID)
+{
+  int i, n = 0;
+
+  if (g_InstanceHash)
+    {
+      for (i = 0; i < N_INSTANCE_BUCKETS; ++i)
+	{
+	  BOOLEAN got_lock;
+	  INSTANCE_BUCKET *ib = &g_InstanceHash->buckets[i];
+	  ACQUIRE_MUTEX_ADAPTIVE (&ib->lock, got_lock);
+
+	  if (got_lock)
+	    {
+	      INSTANCE *current;
+	      for (current = ib->list; current != NULL; current = current->next)
+		++n;
+	      RELEASE_MUTEX (&ib->lock);
+	    }
+	  else
+	    return -1;
+	}
+    }
+
+  return n;
+}
+
+int
+InstanceMaxBucketSize (VOID)
+{
+  int i, n = 0;
+
+  if (g_InstanceHash)
+    {
+      for (i = 0; i < N_INSTANCE_BUCKETS; ++i)
+	{
+	  BOOLEAN got_lock;
+	  int bucket_size = 0;
+	  INSTANCE_BUCKET *ib = &g_InstanceHash->buckets[i];
+	  ACQUIRE_MUTEX_ADAPTIVE (&ib->lock, got_lock);
+
+	  if (got_lock)
+	    {
+	      INSTANCE *current;
+	      for (current = ib->list; current != NULL; current = current->next)
+		  ++bucket_size;
+	      if (bucket_size > n)
+		n = bucket_size;
+	      RELEASE_MUTEX (&ib->lock);
+	    }
+	  else
+	    return -1;
+	}
+    }
+
+  return n;
+}
+
+VOID
+FreeInstanceList (VOID)
+{
+  if (g_InstanceHash)
+    {
+      MYASSERT (NInstances() == 0);
+      MemFree (g_InstanceHash, sizeof (INSTANCE_HASH));
+      g_InstanceHash = NULL;
+    }
+}
+
+BOOLEAN
+AddAdapterToInstanceList (TapAdapterPointer p_Adapter)
+{
+  BOOLEAN got_lock;
+  BOOLEAN ret = FALSE;
+  const int hash = InstanceHashValue(INSTANCE_KEY(p_Adapter));
+  INSTANCE_BUCKET *ib = &g_InstanceHash->buckets[hash];
+
+  DEBUGP (("[TAP] AddAdapterToInstanceList hash=%d\n", hash));
+
+  ACQUIRE_MUTEX_ADAPTIVE (&ib->lock, got_lock);
+
+  if (got_lock)
+    {
+      INSTANCE *i = MemAlloc (sizeof (INSTANCE), FALSE);
+      if (i)
+	{
+	  MYASSERT (p_Adapter);
+	  i->m_Adapter = p_Adapter;
+	  i->next = ib->list;
+	  ib->list = i;
+	  ret = TRUE;
+	}
+      RELEASE_MUTEX (&ib->lock);
+    }
+
+  return ret;
+}
+
+BOOLEAN
+RemoveAdapterFromInstanceList (TapAdapterPointer p_Adapter)
+{
+  BOOLEAN got_lock;
+  BOOLEAN ret = FALSE;
+  INSTANCE_BUCKET *ib = &g_InstanceHash->buckets[InstanceHashValue(INSTANCE_KEY(p_Adapter))];
+
+  ACQUIRE_MUTEX_ADAPTIVE (&ib->lock, got_lock);
+
+  if (got_lock)
+    {
+      INSTANCE *current, *prev=NULL;
+      for (current = ib->list; current != NULL; current = current->next)
+	{
+	  if (current->m_Adapter == p_Adapter) // found match
+	    {
+	      if (prev)
+		prev->next = current->next;
+	      else
+		ib->list = current->next;
+	      MemFree (current->m_Adapter, sizeof (TapAdapter));
+	      MemFree (current, sizeof (INSTANCE));
+	      ret = TRUE;
+	      break;
+	    }
+	  prev = current;
+	}
+      RELEASE_MUTEX (&ib->lock);
+    }
+
+  return ret;
+}
+
+TapAdapterPointer
+LookupAdapterInInstanceList (PDEVICE_OBJECT p_DeviceObject)
+{
+  BOOLEAN got_lock;
+  TapAdapterPointer ret = NULL;
+  INSTANCE_BUCKET *ib = &g_InstanceHash->buckets[InstanceHashValue((PVOID)p_DeviceObject)];
+
+  ACQUIRE_MUTEX_ADAPTIVE (&ib->lock, got_lock);
+
+  if (got_lock)
+    {
+      INSTANCE *current, *prev=NULL;
+      for (current = ib->list; current != NULL; current = current->next)
+	{
+	  if (p_DeviceObject == INSTANCE_KEY (current->m_Adapter)) // found match
+	    {
+	      // move it to head of list
+	      if (prev)
+		{
+		  prev->next = current->next;
+		  current->next = ib->list;
+		  ib->list = current;
+		}
+	      ret = ib->list->m_Adapter;
+	      break;
+	    }
+	  prev = current;
+	}
+      RELEASE_MUTEX (&ib->lock);
+    }
+
+  return ret;
+}