sockoptip4_posix_nonlinux.mx raw

   1  // Copyright 2011 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 (unix && !linux) || windows
   6  
   7  package net
   8  
   9  import (
  10  	"internal/bytealg"
  11  	"runtime"
  12  	"syscall"
  13  )
  14  
  15  func joinIPv4Group(fd *netFD, ifi *Interface, ip IP) error {
  16  	mreq := &syscall.IPMreq{Multiaddr: [4]byte{ip[0], ip[1], ip[2], ip[3]}}
  17  	if err := setIPv4MreqToInterface(mreq, ifi); err != nil {
  18  		return err
  19  	}
  20  	err := fd.pfd.SetsockoptIPMreq(syscall.IPPROTO_IP, syscall.IP_ADD_MEMBERSHIP, mreq)
  21  	runtime.KeepAlive(fd)
  22  	return wrapSyscallError("setsockopt", err)
  23  }
  24  
  25  func setIPv4MreqToInterface(mreq *syscall.IPMreq, ifi *Interface) error {
  26  	if ifi == nil {
  27  		return nil
  28  	}
  29  	ifat, err := ifi.Addrs()
  30  	if err != nil {
  31  		return err
  32  	}
  33  	for _, ifa := range ifat {
  34  		switch v := ifa.(type) {
  35  		case *IPAddr:
  36  			if a := v.IP.To4(); a != nil {
  37  				copy(mreq.Interface[:], a)
  38  				goto done
  39  			}
  40  		case *IPNet:
  41  			if a := v.IP.To4(); a != nil {
  42  				copy(mreq.Interface[:], a)
  43  				goto done
  44  			}
  45  		}
  46  	}
  47  done:
  48  	if bytealg.Equal(mreq.Interface[:], IPv4zero.To4()) {
  49  		return errNoSuchMulticastInterface
  50  	}
  51  	return nil
  52  }
  53