gtsocial-umbx

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control_pktinfo.go (1011B)

      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 
      8 package ipv4
      9 
     10 import (
     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 
     20 func 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 
     35 func 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 }