github.com/Andyfoo/golang/x/net@v0.0.0-20190901054642-57c1bf301704/ipv4/sys_asmreq.go (about)

     1  // Copyright 2012 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  // +build aix darwin dragonfly freebsd netbsd openbsd solaris windows
     6  
     7  package ipv4
     8  
     9  import (
    10  	"net"
    11  	"unsafe"
    12  
    13  	"github.com/Andyfoo/golang/x/net/internal/socket"
    14  )
    15  
    16  func (so *sockOpt) setIPMreq(c *socket.Conn, ifi *net.Interface, grp net.IP) error {
    17  	mreq := ipMreq{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
    18  	if err := setIPMreqInterface(&mreq, ifi); err != nil {
    19  		return err
    20  	}
    21  	b := (*[sizeofIPMreq]byte)(unsafe.Pointer(&mreq))[:sizeofIPMreq]
    22  	return so.Set(c, b)
    23  }
    24  
    25  func (so *sockOpt) getMulticastIf(c *socket.Conn) (*net.Interface, error) {
    26  	var b [4]byte
    27  	if _, err := so.Get(c, b[:]); err != nil {
    28  		return nil, err
    29  	}
    30  	ifi, err := netIP4ToInterface(net.IPv4(b[0], b[1], b[2], b[3]))
    31  	if err != nil {
    32  		return nil, err
    33  	}
    34  	return ifi, nil
    35  }
    36  
    37  func (so *sockOpt) setMulticastIf(c *socket.Conn, ifi *net.Interface) error {
    38  	ip, err := netInterfaceToIP4(ifi)
    39  	if err != nil {
    40  		return err
    41  	}
    42  	var b [4]byte
    43  	copy(b[:], ip)
    44  	return so.Set(c, b[:])
    45  }
    46  
    47  func setIPMreqInterface(mreq *ipMreq, ifi *net.Interface) error {
    48  	if ifi == nil {
    49  		return nil
    50  	}
    51  	ifat, err := ifi.Addrs()
    52  	if err != nil {
    53  		return err
    54  	}
    55  	for _, ifa := range ifat {
    56  		switch ifa := ifa.(type) {
    57  		case *net.IPAddr:
    58  			if ip := ifa.IP.To4(); ip != nil {
    59  				copy(mreq.Interface[:], ip)
    60  				return nil
    61  			}
    62  		case *net.IPNet:
    63  			if ip := ifa.IP.To4(); ip != nil {
    64  				copy(mreq.Interface[:], ip)
    65  				return nil
    66  			}
    67  		}
    68  	}
    69  	return errNoSuchInterface
    70  }
    71  
    72  func netIP4ToInterface(ip net.IP) (*net.Interface, error) {
    73  	ift, err := net.Interfaces()
    74  	if err != nil {
    75  		return nil, err
    76  	}
    77  	for _, ifi := range ift {
    78  		ifat, err := ifi.Addrs()
    79  		if err != nil {
    80  			return nil, err
    81  		}
    82  		for _, ifa := range ifat {
    83  			switch ifa := ifa.(type) {
    84  			case *net.IPAddr:
    85  				if ip.Equal(ifa.IP) {
    86  					return &ifi, nil
    87  				}
    88  			case *net.IPNet:
    89  				if ip.Equal(ifa.IP) {
    90  					return &ifi, nil
    91  				}
    92  			}
    93  		}
    94  	}
    95  	return nil, errNoSuchInterface
    96  }
    97  
    98  func netInterfaceToIP4(ifi *net.Interface) (net.IP, error) {
    99  	if ifi == nil {
   100  		return net.IPv4zero.To4(), nil
   101  	}
   102  	ifat, err := ifi.Addrs()
   103  	if err != nil {
   104  		return nil, err
   105  	}
   106  	for _, ifa := range ifat {
   107  		switch ifa := ifa.(type) {
   108  		case *net.IPAddr:
   109  			if ip := ifa.IP.To4(); ip != nil {
   110  				return ip, nil
   111  			}
   112  		case *net.IPNet:
   113  			if ip := ifa.IP.To4(); ip != nil {
   114  				return ip, nil
   115  			}
   116  		}
   117  	}
   118  	return nil, errNoSuchInterface
   119  }