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sys_asmreq.go (2657B)

      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 //go:build aix || darwin || dragonfly || freebsd || netbsd || openbsd || solaris || windows
      6 // +build aix darwin dragonfly freebsd netbsd openbsd solaris windows
      7 
      8 package ipv4
      9 
     10 import (
     11 	"errors"
     12 	"net"
     13 	"unsafe"
     14 
     15 	"golang.org/x/net/internal/socket"
     16 )
     17 
     18 var errNoSuchInterface = errors.New("no such interface")
     19 
     20 func (so *sockOpt) setIPMreq(c *socket.Conn, ifi *net.Interface, grp net.IP) error {
     21 	mreq := ipMreq{Multiaddr: [4]byte{grp[0], grp[1], grp[2], grp[3]}}
     22 	if err := setIPMreqInterface(&mreq, ifi); err != nil {
     23 		return err
     24 	}
     25 	b := (*[sizeofIPMreq]byte)(unsafe.Pointer(&mreq))[:sizeofIPMreq]
     26 	return so.Set(c, b)
     27 }
     28 
     29 func (so *sockOpt) getMulticastIf(c *socket.Conn) (*net.Interface, error) {
     30 	var b [4]byte
     31 	if _, err := so.Get(c, b[:]); err != nil {
     32 		return nil, err
     33 	}
     34 	ifi, err := netIP4ToInterface(net.IPv4(b[0], b[1], b[2], b[3]))
     35 	if err != nil {
     36 		return nil, err
     37 	}
     38 	return ifi, nil
     39 }
     40 
     41 func (so *sockOpt) setMulticastIf(c *socket.Conn, ifi *net.Interface) error {
     42 	ip, err := netInterfaceToIP4(ifi)
     43 	if err != nil {
     44 		return err
     45 	}
     46 	var b [4]byte
     47 	copy(b[:], ip)
     48 	return so.Set(c, b[:])
     49 }
     50 
     51 func setIPMreqInterface(mreq *ipMreq, ifi *net.Interface) error {
     52 	if ifi == nil {
     53 		return nil
     54 	}
     55 	ifat, err := ifi.Addrs()
     56 	if err != nil {
     57 		return err
     58 	}
     59 	for _, ifa := range ifat {
     60 		switch ifa := ifa.(type) {
     61 		case *net.IPAddr:
     62 			if ip := ifa.IP.To4(); ip != nil {
     63 				copy(mreq.Interface[:], ip)
     64 				return nil
     65 			}
     66 		case *net.IPNet:
     67 			if ip := ifa.IP.To4(); ip != nil {
     68 				copy(mreq.Interface[:], ip)
     69 				return nil
     70 			}
     71 		}
     72 	}
     73 	return errNoSuchInterface
     74 }
     75 
     76 func netIP4ToInterface(ip net.IP) (*net.Interface, error) {
     77 	ift, err := net.Interfaces()
     78 	if err != nil {
     79 		return nil, err
     80 	}
     81 	for _, ifi := range ift {
     82 		ifat, err := ifi.Addrs()
     83 		if err != nil {
     84 			return nil, err
     85 		}
     86 		for _, ifa := range ifat {
     87 			switch ifa := ifa.(type) {
     88 			case *net.IPAddr:
     89 				if ip.Equal(ifa.IP) {
     90 					return &ifi, nil
     91 				}
     92 			case *net.IPNet:
     93 				if ip.Equal(ifa.IP) {
     94 					return &ifi, nil
     95 				}
     96 			}
     97 		}
     98 	}
     99 	return nil, errNoSuchInterface
    100 }
    101 
    102 func netInterfaceToIP4(ifi *net.Interface) (net.IP, error) {
    103 	if ifi == nil {
    104 		return net.IPv4zero.To4(), nil
    105 	}
    106 	ifat, err := ifi.Addrs()
    107 	if err != nil {
    108 		return nil, err
    109 	}
    110 	for _, ifa := range ifat {
    111 		switch ifa := ifa.(type) {
    112 		case *net.IPAddr:
    113 			if ip := ifa.IP.To4(); ip != nil {
    114 				return ip, nil
    115 			}
    116 		case *net.IPNet:
    117 			if ip := ifa.IP.To4(); ip != nil {
    118 				return ip, nil
    119 			}
    120 		}
    121 	}
    122 	return nil, errNoSuchInterface
    123 }