syncthing/vendor/golang.org/x/net/ipv4/control_unix.go

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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build darwin dragonfly freebsd linux netbsd openbsd solaris
package ipv4
import (
"os"
"syscall"
"unsafe"
"golang.org/x/net/internal/iana"
)
func setControlMessage(s uintptr, opt *rawOpt, cf ControlFlags, on bool) error {
opt.Lock()
defer opt.Unlock()
if cf&FlagTTL != 0 && sockOpts[ssoReceiveTTL].name > 0 {
if err := setInt(s, &sockOpts[ssoReceiveTTL], boolint(on)); err != nil {
return err
}
if on {
opt.set(FlagTTL)
} else {
opt.clear(FlagTTL)
}
}
if sockOpts[ssoPacketInfo].name > 0 {
if cf&(FlagSrc|FlagDst|FlagInterface) != 0 {
if err := setInt(s, &sockOpts[ssoPacketInfo], boolint(on)); err != nil {
return err
}
if on {
opt.set(cf & (FlagSrc | FlagDst | FlagInterface))
} else {
opt.clear(cf & (FlagSrc | FlagDst | FlagInterface))
}
}
} else {
if cf&FlagDst != 0 && sockOpts[ssoReceiveDst].name > 0 {
if err := setInt(s, &sockOpts[ssoReceiveDst], boolint(on)); err != nil {
return err
}
if on {
opt.set(FlagDst)
} else {
opt.clear(FlagDst)
}
}
if cf&FlagInterface != 0 && sockOpts[ssoReceiveInterface].name > 0 {
if err := setInt(s, &sockOpts[ssoReceiveInterface], boolint(on)); err != nil {
return err
}
if on {
opt.set(FlagInterface)
} else {
opt.clear(FlagInterface)
}
}
}
return nil
}
func newControlMessage(opt *rawOpt) (oob []byte) {
opt.RLock()
var l int
if opt.isset(FlagTTL) && ctlOpts[ctlTTL].name > 0 {
l += syscall.CmsgSpace(ctlOpts[ctlTTL].length)
}
if ctlOpts[ctlPacketInfo].name > 0 {
if opt.isset(FlagSrc | FlagDst | FlagInterface) {
l += syscall.CmsgSpace(ctlOpts[ctlPacketInfo].length)
}
} else {
if opt.isset(FlagDst) && ctlOpts[ctlDst].name > 0 {
l += syscall.CmsgSpace(ctlOpts[ctlDst].length)
}
if opt.isset(FlagInterface) && ctlOpts[ctlInterface].name > 0 {
l += syscall.CmsgSpace(ctlOpts[ctlInterface].length)
}
}
if l > 0 {
oob = make([]byte, l)
}
opt.RUnlock()
return
}
func parseControlMessage(b []byte) (*ControlMessage, error) {
if len(b) == 0 {
return nil, nil
}
cmsgs, err := syscall.ParseSocketControlMessage(b)
if err != nil {
return nil, os.NewSyscallError("parse socket control message", err)
}
cm := &ControlMessage{}
for _, m := range cmsgs {
if m.Header.Level != iana.ProtocolIP {
continue
}
switch int(m.Header.Type) {
case ctlOpts[ctlTTL].name:
ctlOpts[ctlTTL].parse(cm, m.Data[:])
case ctlOpts[ctlDst].name:
ctlOpts[ctlDst].parse(cm, m.Data[:])
case ctlOpts[ctlInterface].name:
ctlOpts[ctlInterface].parse(cm, m.Data[:])
case ctlOpts[ctlPacketInfo].name:
ctlOpts[ctlPacketInfo].parse(cm, m.Data[:])
}
}
return cm, nil
}
func marshalControlMessage(cm *ControlMessage) (oob []byte) {
if cm == nil {
return nil
}
var l int
pktinfo := false
if ctlOpts[ctlPacketInfo].name > 0 && (cm.Src.To4() != nil || cm.IfIndex > 0) {
pktinfo = true
l += syscall.CmsgSpace(ctlOpts[ctlPacketInfo].length)
}
if l > 0 {
oob = make([]byte, l)
b := oob
if pktinfo {
b = ctlOpts[ctlPacketInfo].marshal(b, cm)
}
}
return
}
func marshalTTL(b []byte, cm *ControlMessage) []byte {
m := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
m.Level = iana.ProtocolIP
m.Type = sysIP_RECVTTL
m.SetLen(syscall.CmsgLen(1))
return b[syscall.CmsgSpace(1):]
}
func parseTTL(cm *ControlMessage, b []byte) {
cm.TTL = int(*(*byte)(unsafe.Pointer(&b[:1][0])))
}