control_zos.go

Documentation: golang.org/x/net/ipv4

     1  // Copyright 2020 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  package ipv4
     6  
     7  import (
     8  	"net"
     9  	"unsafe"
    10  
    11  	"golang.org/x/net/internal/iana"
    12  	"golang.org/x/net/internal/socket"
    13  
    14  	"golang.org/x/sys/unix"
    15  )
    16  
    17  func marshalPacketInfo(b []byte, cm *ControlMessage) []byte {
    18  	m := socket.ControlMessage(b)
    19  	m.MarshalHeader(iana.ProtocolIP, unix.IP_PKTINFO, sizeofInetPktinfo)
    20  	if cm != nil {
    21  		pi := (*inetPktinfo)(unsafe.Pointer(&m.Data(sizeofInetPktinfo)[0]))
    22  		if ip := cm.Src.To4(); ip != nil {
    23  			copy(pi.Addr[:], ip)
    24  		}
    25  		if cm.IfIndex > 0 {
    26  			pi.setIfindex(cm.IfIndex)
    27  		}
    28  	}
    29  	return m.Next(sizeofInetPktinfo)
    30  }
    31  
    32  func parsePacketInfo(cm *ControlMessage, b []byte) {
    33  	pi := (*inetPktinfo)(unsafe.Pointer(&b[0]))
    34  	cm.IfIndex = int(pi.Ifindex)
    35  	if len(cm.Dst) < net.IPv4len {
    36  		cm.Dst = make(net.IP, net.IPv4len)
    37  	}
    38  	copy(cm.Dst, pi.Addr[:])
    39  }
    40  
    41  func setControlMessage(c *socket.Conn, opt *rawOpt, cf ControlFlags, on bool) error {
    42  	opt.Lock()
    43  	defer opt.Unlock()
    44  	if so, ok := sockOpts[ssoReceiveTTL]; ok && cf&FlagTTL != 0 {
    45  		if err := so.SetInt(c, boolint(on)); err != nil {
    46  			return err
    47  		}
    48  		if on {
    49  			opt.set(FlagTTL)
    50  		} else {
    51  			opt.clear(FlagTTL)
    52  		}
    53  	}
    54  	if so, ok := sockOpts[ssoPacketInfo]; ok {
    55  		if cf&(FlagSrc|FlagDst|FlagInterface) != 0 {
    56  			if err := so.SetInt(c, boolint(on)); err != nil {
    57  				return err
    58  			}
    59  			if on {
    60  				opt.set(cf & (FlagSrc | FlagDst | FlagInterface))
    61  			} else {
    62  				opt.clear(cf & (FlagSrc | FlagDst | FlagInterface))
    63  			}
    64  		}
    65  	} else {
    66  		if so, ok := sockOpts[ssoReceiveDst]; ok && cf&FlagDst != 0 {
    67  			if err := so.SetInt(c, boolint(on)); err != nil {
    68  				return err
    69  			}
    70  			if on {
    71  				opt.set(FlagDst)
    72  			} else {
    73  				opt.clear(FlagDst)
    74  			}
    75  		}
    76  		if so, ok := sockOpts[ssoReceiveInterface]; ok && cf&FlagInterface != 0 {
    77  			if err := so.SetInt(c, boolint(on)); err != nil {
    78  				return err
    79  			}
    80  			if on {
    81  				opt.set(FlagInterface)
    82  			} else {
    83  				opt.clear(FlagInterface)
    84  			}
    85  		}
    86  	}
    87  	return nil
    88  }
    89
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