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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2020 WireGuard LLC. All Rights Reserved.
*/
package wintun
import (
"syscall"
"unsafe"
"golang.org/x/sys/windows"
)
type Session struct {
handle uintptr
}
const (
PacketSizeMax = 0xffff // Maximum packet size
RingCapacityMin = 0x20000 // Minimum ring capacity (128 kiB)
RingCapacityMax = 0x4000000 // Maximum ring capacity (64 MiB)
)
// Packet with data
type Packet struct {
Next *Packet // Pointer to next packet in queue
Size uint32 // Size of packet (max WINTUN_MAX_IP_PACKET_SIZE)
Data *[PacketSizeMax]byte // Pointer to layer 3 IPv4 or IPv6 packet
}
var (
procWintunAllocateSendPacket = modwintun.NewProc("WintunAllocateSendPacket").Addr()
procWintunEndSession = modwintun.NewProc("WintunEndSession")
procWintunGetReadWaitEvent = modwintun.NewProc("WintunGetReadWaitEvent")
procWintunReceivePacket = modwintun.NewProc("WintunReceivePacket").Addr()
procWintunReleaseReceivePacket = modwintun.NewProc("WintunReleaseReceivePacket").Addr()
procWintunSendPacket = modwintun.NewProc("WintunSendPacket").Addr()
procWintunStartSession = modwintun.NewProc("WintunStartSession")
)
func (wintun *Adapter) StartSession(capacity uint32) (session Session, err error) {
r0, _, e1 := syscall.Syscall(procWintunStartSession.Addr(), 2, uintptr(wintun.handle), uintptr(capacity), 0)
if r0 == 0 {
err = e1
} else {
session = Session{r0}
}
return
}
func (session Session) End() {
syscall.Syscall(procWintunEndSession.Addr(), 1, session.handle, 0, 0)
session.handle = 0
}
func (session Session) ReadWaitEvent() (handle windows.Handle) {
r0, _, _ := syscall.Syscall(procWintunGetReadWaitEvent.Addr(), 1, session.handle, 0, 0)
handle = windows.Handle(r0)
return
}
func (session Session) ReceivePacket() (packet []byte, err error) {
var packetSize uint32
r0, _, e1 := syscall.Syscall(procWintunReceivePacket, 2, session.handle, uintptr(unsafe.Pointer(&packetSize)), 0)
if r0 == 0 {
err = e1
return
}
unsafeSlice(unsafe.Pointer(&packet), unsafe.Pointer(r0), int(packetSize))
return
}
func (session Session) ReleaseReceivePacket(packet []byte) {
syscall.Syscall(procWintunReleaseReceivePacket, 2, session.handle, uintptr(unsafe.Pointer(&packet[0])), 0)
}
func (session Session) AllocateSendPacket(packetSize int) (packet []byte, err error) {
r0, _, e1 := syscall.Syscall(procWintunAllocateSendPacket, 2, session.handle, uintptr(packetSize), 0)
if r0 == 0 {
err = e1
return
}
unsafeSlice(unsafe.Pointer(&packet), unsafe.Pointer(r0), int(packetSize))
return
}
func (session Session) SendPacket(packet []byte) {
syscall.Syscall(procWintunSendPacket, 2, session.handle, uintptr(unsafe.Pointer(&packet[0])), 0)
}
// unsafeSlice updates the slice slicePtr to be a slice
// referencing the provided data with its length & capacity set to
// lenCap.
//
// TODO: when Go 1.16 or Go 1.17 is the minimum supported version,
// update callers to use unsafe.Slice instead of this.
func unsafeSlice(slicePtr, data unsafe.Pointer, lenCap int) {
type sliceHeader struct {
Data unsafe.Pointer
Len int
Cap int
}
h := (*sliceHeader)(slicePtr)
h.Data = data
h.Len = lenCap
h.Cap = lenCap
}
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