mirror of
https://git.zx2c4.com/wireguard-go
synced 2024-11-15 01:05:15 +01:00
66 lines
1.7 KiB
Go
66 lines
1.7 KiB
Go
//go:build linux
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/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
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*/
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package conn
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import (
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"fmt"
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"unsafe"
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"golang.org/x/sys/unix"
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)
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const (
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sizeOfGSOData = 2
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)
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// getGSOSize parses control for UDP_GRO and if found returns its GSO size data.
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func getGSOSize(control []byte) (int, error) {
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var (
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hdr unix.Cmsghdr
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data []byte
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rem = control
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err error
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)
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for len(rem) > unix.SizeofCmsghdr {
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hdr, data, rem, err = unix.ParseOneSocketControlMessage(rem)
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if err != nil {
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return 0, fmt.Errorf("error parsing socket control message: %w", err)
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}
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if hdr.Level == unix.SOL_UDP && hdr.Type == unix.UDP_GRO && len(data) >= sizeOfGSOData {
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var gso uint16
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copy(unsafe.Slice((*byte)(unsafe.Pointer(&gso)), sizeOfGSOData), data[:sizeOfGSOData])
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return int(gso), nil
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}
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}
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return 0, nil
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}
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// setGSOSize sets a UDP_SEGMENT in control based on gsoSize. It leaves existing
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// data in control untouched.
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func setGSOSize(control *[]byte, gsoSize uint16) {
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existingLen := len(*control)
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avail := cap(*control) - existingLen
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space := unix.CmsgSpace(sizeOfGSOData)
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if avail < space {
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return
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}
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*control = (*control)[:cap(*control)]
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gsoControl := (*control)[existingLen:]
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hdr := (*unix.Cmsghdr)(unsafe.Pointer(&(gsoControl)[0]))
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hdr.Level = unix.SOL_UDP
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hdr.Type = unix.UDP_SEGMENT
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hdr.SetLen(unix.CmsgLen(sizeOfGSOData))
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copy((gsoControl)[unix.SizeofCmsghdr:], unsafe.Slice((*byte)(unsafe.Pointer(&gsoSize)), sizeOfGSOData))
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*control = (*control)[:existingLen+space]
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}
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// gsoControlSize returns the recommended buffer size for pooling UDP
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// offloading control data.
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var gsoControlSize = unix.CmsgSpace(sizeOfGSOData)
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