1// Copyright 2014 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5//go:build darwin || linux || solaris
6// +build darwin linux solaris
7
8package ipv4
9
10import (
11	"net"
12	"unsafe"
13
14	"golang.org/x/net/internal/iana"
15	"golang.org/x/net/internal/socket"
16
17	"golang.org/x/sys/unix"
18)
19
20func marshalPacketInfo(b []byte, cm *ControlMessage) []byte {
21	m := socket.ControlMessage(b)
22	m.MarshalHeader(iana.ProtocolIP, unix.IP_PKTINFO, sizeofInetPktinfo)
23	if cm != nil {
24		pi := (*inetPktinfo)(unsafe.Pointer(&m.Data(sizeofInetPktinfo)[0]))
25		if ip := cm.Src.To4(); ip != nil {
26			copy(pi.Spec_dst[:], ip)
27		}
28		if cm.IfIndex > 0 {
29			pi.setIfindex(cm.IfIndex)
30		}
31	}
32	return m.Next(sizeofInetPktinfo)
33}
34
35func parsePacketInfo(cm *ControlMessage, b []byte) {
36	pi := (*inetPktinfo)(unsafe.Pointer(&b[0]))
37	cm.IfIndex = int(pi.Ifindex)
38	if len(cm.Dst) < net.IPv4len {
39		cm.Dst = make(net.IP, net.IPv4len)
40	}
41	copy(cm.Dst, pi.Addr[:])
42}
43