mirror of
https://github.com/SagerNet/sing-tun.git
synced 2025-04-03 20:07:40 +03:00
91 lines
3 KiB
Go
91 lines
3 KiB
Go
// Copyright 2019 The gVisor Authors.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
//go:build linux
|
|
// +build linux
|
|
|
|
package fdbased
|
|
|
|
import (
|
|
"fmt"
|
|
"unsafe"
|
|
|
|
"github.com/sagernet/sing-tun/internal/fdbased/stopfd"
|
|
|
|
"golang.org/x/sys/unix"
|
|
"gvisor.dev/gvisor/pkg/atomicbitops"
|
|
)
|
|
|
|
// tPacketHdrlen is the TPACKET_HDRLEN variable defined in <linux/if_packet.h>.
|
|
var tPacketHdrlen = tPacketAlign(unsafe.Sizeof(tPacketHdr{}) + unsafe.Sizeof(unix.RawSockaddrLinklayer{}))
|
|
|
|
// tpStatus returns the frame status field.
|
|
// The status is concurrently updated by the kernel as a result we must
|
|
// use atomic operations to prevent races.
|
|
func (t tPacketHdr) tpStatus() uint32 {
|
|
hdr := unsafe.Pointer(&t[0])
|
|
statusPtr := unsafe.Pointer(uintptr(hdr) + uintptr(tpStatusOffset))
|
|
return (*atomicbitops.Uint32)(statusPtr).Load()
|
|
}
|
|
|
|
// setTPStatus set's the frame status to the provided status.
|
|
// The status is concurrently updated by the kernel as a result we must
|
|
// use atomic operations to prevent races.
|
|
func (t tPacketHdr) setTPStatus(status uint32) {
|
|
hdr := unsafe.Pointer(&t[0])
|
|
statusPtr := unsafe.Pointer(uintptr(hdr) + uintptr(tpStatusOffset))
|
|
(*atomicbitops.Uint32)(statusPtr).Store(status)
|
|
}
|
|
|
|
func newPacketMMapDispatcher(fd int, e *endpoint) (linkDispatcher, error) {
|
|
stopFD, err := stopfd.New()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
d := &packetMMapDispatcher{
|
|
StopFD: stopFD,
|
|
fd: fd,
|
|
e: e,
|
|
}
|
|
pageSize := unix.Getpagesize()
|
|
if tpBlockSize%pageSize != 0 {
|
|
return nil, fmt.Errorf("tpBlockSize: %d is not page aligned, pagesize: %d", tpBlockSize, pageSize)
|
|
}
|
|
tReq := tPacketReq{
|
|
tpBlockSize: uint32(tpBlockSize),
|
|
tpBlockNR: uint32(tpBlockNR),
|
|
tpFrameSize: uint32(tpFrameSize),
|
|
tpFrameNR: uint32(tpFrameNR),
|
|
}
|
|
// Setup PACKET_RX_RING.
|
|
if err := setsockopt(d.fd, unix.SOL_PACKET, unix.PACKET_RX_RING, unsafe.Pointer(&tReq), unsafe.Sizeof(tReq)); err != nil {
|
|
return nil, fmt.Errorf("failed to enable PACKET_RX_RING: %v", err)
|
|
}
|
|
// Let's mmap the blocks.
|
|
sz := tpBlockSize * tpBlockNR
|
|
buf, err := unix.Mmap(d.fd, 0, sz, unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("unix.Mmap(...,0, %v, ...) failed = %v", sz, err)
|
|
}
|
|
d.ringBuffer = buf
|
|
return d, nil
|
|
}
|
|
|
|
func setsockopt(fd, level, name int, val unsafe.Pointer, vallen uintptr) error {
|
|
if _, _, errno := unix.Syscall6(unix.SYS_SETSOCKOPT, uintptr(fd), uintptr(level), uintptr(name), uintptr(val), vallen, 0); errno != 0 {
|
|
return error(errno)
|
|
}
|
|
|
|
return nil
|
|
}
|