github.com/hxx258456/ccgo@v0.0.5-0.20230213014102-48b35f46f66f/net/ipv4/control_pktinfo.go (about)

     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  	"github.com/hxx258456/ccgo/net/internal/iana"
    15  	"github.com/hxx258456/ccgo/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  }