control_zos.go raw

   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