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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2018-2020 WireGuard LLC. All Rights Reserved.
*/
#include "pch.h"
#pragma warning(disable : 4200) /* nonstandard: zero-sized array in struct/union */
#define TUN_ALIGNMENT sizeof(ULONG)
#define TUN_ALIGN(Size) (((ULONG)(Size) + ((ULONG)TUN_ALIGNMENT - 1)) & ~((ULONG)TUN_ALIGNMENT - 1))
#define TUN_IS_ALIGNED(Size) (!((ULONG)(Size) & ((ULONG)TUN_ALIGNMENT - 1)))
#define TUN_MAX_PACKET_SIZE TUN_ALIGN(sizeof(TUN_PACKET) + WINTUN_MAX_IP_PACKET_SIZE)
#define TUN_RING_CAPACITY(Size) ((Size) - sizeof(TUN_RING) - (TUN_MAX_PACKET_SIZE - TUN_ALIGNMENT))
#define TUN_RING_SIZE(Capacity) (sizeof(TUN_RING) + (Capacity) + (TUN_MAX_PACKET_SIZE - TUN_ALIGNMENT))
#define TUN_RING_WRAP(Value, Capacity) ((Value) & (Capacity - 1))
typedef struct _TUN_PACKET
{
ULONG Size;
UCHAR _Field_size_bytes_(Size)
Data[];
} TUN_PACKET;
typedef struct _TUN_RING
{
volatile ULONG Head;
volatile ULONG Tail;
volatile LONG Alertable;
UCHAR Data[];
} TUN_RING;
#define TUN_IOCTL_REGISTER_RINGS CTL_CODE(51820U, 0x970U, METHOD_BUFFERED, FILE_READ_DATA | FILE_WRITE_DATA)
typedef struct _TUN_REGISTER_RINGS
{
struct
{
ULONG RingSize;
TUN_RING *Ring;
HANDLE TailMoved;
} Send, Receive;
} TUN_REGISTER_RINGS;
typedef struct _TUN_SESSION
{
ULONG Capacity;
TUN_REGISTER_RINGS Descriptor;
HANDLE Handle;
} TUN_SESSION;
WINTUN_STATUS WINAPI
WintunStartSession(_In_ const WINTUN_ADAPTER *Adapter, _In_ DWORD Capacity, _Out_ TUN_SESSION **Session)
{
HANDLE Heap = GetProcessHeap();
*Session = HeapAlloc(Heap, 0, sizeof(TUN_SESSION));
if (!*Session)
return LOG(WINTUN_LOG_ERR, L"Out of memory"), ERROR_OUTOFMEMORY;
const ULONG RingSize = TUN_RING_SIZE(Capacity);
DWORD Result;
BYTE *AllocatedRegion = VirtualAlloc(0, (size_t)RingSize * 2, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
if (!AllocatedRegion)
{
Result = LOG_LAST_ERROR(L"Failed to allocate ring memory");
goto cleanupRings;
}
(*Session)->Descriptor.Send.RingSize = RingSize;
(*Session)->Descriptor.Send.Ring = (TUN_RING *)AllocatedRegion;
(*Session)->Descriptor.Send.TailMoved = CreateEventW(SecurityAttributes, FALSE, FALSE, NULL);
if (!(*Session)->Descriptor.Send.TailMoved)
{
Result = LOG_LAST_ERROR(L"Failed to create send event");
goto cleanupAllocatedRegion;
}
(*Session)->Descriptor.Receive.RingSize = RingSize;
(*Session)->Descriptor.Receive.Ring = (TUN_RING *)(AllocatedRegion + RingSize);
(*Session)->Descriptor.Receive.TailMoved = CreateEvent(SecurityAttributes, FALSE, FALSE, NULL);
if (!(*Session)->Descriptor.Receive.TailMoved)
{
Result = LOG_LAST_ERROR(L"Failed to create receive event");
goto cleanupSendTailMoved;
}
Result = WintunGetAdapterDeviceObject(Adapter, &(*Session)->Handle);
if (Result != ERROR_SUCCESS)
{
LOG(WINTUN_LOG_ERR, L"Failed to open adapter device object");
goto cleanupReceiveTailMoved;
}
DWORD BytesReturned;
if (!DeviceIoControl(
(*Session)->Handle,
TUN_IOCTL_REGISTER_RINGS,
&(*Session)->Descriptor,
sizeof(TUN_REGISTER_RINGS),
NULL,
0,
&BytesReturned,
NULL))
{
Result = LOG_LAST_ERROR(L"Failed to perform ioctl");
goto cleanupHandle;
}
(*Session)->Capacity = Capacity;
return ERROR_SUCCESS;
cleanupHandle:
CloseHandle((*Session)->Handle);
cleanupReceiveTailMoved:
CloseHandle((*Session)->Descriptor.Receive.TailMoved);
cleanupSendTailMoved:
CloseHandle((*Session)->Descriptor.Send.TailMoved);
cleanupAllocatedRegion:
VirtualFree(AllocatedRegion, 0, MEM_RELEASE);
cleanupRings:
HeapFree(Heap, 0, *Session);
*Session = NULL;
return Result;
}
void WINAPI
WintunEndSession(_In_ TUN_SESSION *Session)
{
SetEvent(Session->Descriptor.Send.TailMoved); // wake the reader if it's sleeping
CloseHandle(Session->Handle);
CloseHandle(Session->Descriptor.Send.TailMoved);
CloseHandle(Session->Descriptor.Receive.TailMoved);
VirtualFree(Session->Descriptor.Send.Ring, 0, MEM_RELEASE);
HeapFree(GetProcessHeap(), 0, Session);
}
BOOL WINAPI
WintunIsPacketAvailable(_In_ TUN_SESSION *Session)
{
return InterlockedGetU(&Session->Descriptor.Send.Ring->Head) !=
InterlockedGetU(&Session->Descriptor.Send.Ring->Tail);
}
WINTUN_STATUS WINAPI
WintunWaitForPacket(_In_ TUN_SESSION *Session, _In_ DWORD Milliseconds)
{
return WaitForSingleObject(Session->Descriptor.Send.TailMoved, Milliseconds);
}
WINTUN_STATUS WINAPI
WintunReceivePackets(_In_ TUN_SESSION *Session, _Inout_ WINTUN_PACKET *Queue)
{
ULONG BuffHead = InterlockedGetU(&Session->Descriptor.Send.Ring->Head);
if (BuffHead >= Session->Capacity)
return ERROR_HANDLE_EOF;
for (; Queue; Queue = Queue->Next)
{
const ULONG BuffTail = InterlockedGetU(&Session->Descriptor.Send.Ring->Tail);
if (BuffTail >= Session->Capacity)
return ERROR_HANDLE_EOF;
if (BuffHead == BuffTail)
return ERROR_NO_MORE_ITEMS;
const ULONG BuffContent = TUN_RING_WRAP(BuffTail - BuffHead, Session->Capacity);
if (BuffContent < sizeof(TUN_PACKET))
return ERROR_INVALID_DATA;
const TUN_PACKET *Packet = (TUN_PACKET *)&Session->Descriptor.Send.Ring->Data[BuffHead];
if (Packet->Size > WINTUN_MAX_IP_PACKET_SIZE)
return ERROR_INVALID_DATA;
const ULONG AlignedPacketSize = TUN_ALIGN(sizeof(TUN_PACKET) + Packet->Size);
if (AlignedPacketSize > BuffContent)
return ERROR_INVALID_DATA;
Queue->Size = Packet->Size;
memcpy(Queue->Data, Packet->Data, Packet->Size);
BuffHead = TUN_RING_WRAP(BuffHead + AlignedPacketSize, Session->Capacity);
InterlockedSetU(&Session->Descriptor.Send.Ring->Head, BuffHead);
}
return ERROR_SUCCESS;
}
WINTUN_STATUS WINAPI
WintunSendPackets(_In_ TUN_SESSION *Session, _In_ const WINTUN_PACKET *Queue)
{
ULONG BuffTail = InterlockedGetU(&Session->Descriptor.Receive.Ring->Tail);
if (BuffTail >= Session->Capacity)
return ERROR_HANDLE_EOF;
for (; Queue; Queue = Queue->Next)
{
const ULONG PacketSize = Queue->Size;
const ULONG AlignedPacketSize = TUN_ALIGN(sizeof(TUN_PACKET) + PacketSize);
const ULONG BuffHead = InterlockedGetU(&Session->Descriptor.Receive.Ring->Head);
if (BuffHead >= Session->Capacity)
return ERROR_HANDLE_EOF;
const ULONG BuffSpace = TUN_RING_WRAP(BuffHead - BuffTail - TUN_ALIGNMENT, Session->Capacity);
if (AlignedPacketSize > BuffSpace)
return ERROR_BUFFER_OVERFLOW; /* Dropping when ring is full. */
TUN_PACKET *Packet = (TUN_PACKET *)&Session->Descriptor.Receive.Ring->Data[BuffTail];
Packet->Size = PacketSize;
memcpy(Packet->Data, Queue->Data, PacketSize);
BuffTail = TUN_RING_WRAP(BuffTail + AlignedPacketSize, Session->Capacity);
InterlockedSetU(&Session->Descriptor.Receive.Ring->Tail, BuffTail);
if (InterlockedGet(&Session->Descriptor.Receive.Ring->Alertable))
SetEvent(Session->Descriptor.Receive.TailMoved);
}
return ERROR_SUCCESS;
}
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