github.com/psiphon-labs/psiphon-tunnel-core@v2.0.28+incompatible/psiphon/common/networkInterface.go (about)

     1  /*
     2   * Copyright (c) 2015, Psiphon Inc.
     3   * All rights reserved.
     4   *
     5   * This program is free software: you can redistribute it and/or modify
     6   * it under the terms of the GNU General Public License as published by
     7   * the Free Software Foundation, either version 3 of the License, or
     8   * (at your option) any later version.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package common
    21  
    22  import (
    23  	"net"
    24  
    25  	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/errors"
    26  )
    27  
    28  // GetInterfaceIPAddresses takes an interface name, such as "eth0", and
    29  // returns the first non-link local IPv4 and IPv6 addresses associated with
    30  // it. Either of the IPv4 or IPv6 address may be nil. If neither type of
    31  // address is found, an error is returned.
    32  func GetInterfaceIPAddresses(interfaceName string) (net.IP, net.IP, error) {
    33  
    34  	var IPv4Address, IPv6Address net.IP
    35  
    36  	availableInterfaces, err := net.InterfaceByName(interfaceName)
    37  	if err != nil {
    38  		return nil, nil, errors.Trace(err)
    39  	}
    40  
    41  	addrs, err := availableInterfaces.Addrs()
    42  	if err != nil {
    43  		return nil, nil, errors.Trace(err)
    44  	}
    45  
    46  	for _, addr := range addrs {
    47  
    48  		ipNet := addr.(*net.IPNet)
    49  		if ipNet == nil {
    50  			continue
    51  		}
    52  
    53  		if ipNet.IP.To4() != nil {
    54  			if IPv4Address == nil && !ipNet.IP.IsLinkLocalUnicast() {
    55  				IPv4Address = ipNet.IP
    56  			}
    57  		} else {
    58  			if IPv6Address == nil && !ipNet.IP.IsLinkLocalUnicast() {
    59  				IPv6Address = ipNet.IP
    60  			}
    61  		}
    62  
    63  		if IPv4Address != nil && IPv6Address != nil {
    64  			break
    65  		}
    66  	}
    67  
    68  	if IPv4Address != nil || IPv6Address != nil {
    69  		return IPv4Address, IPv6Address, nil
    70  	}
    71  
    72  	return nil, nil, errors.Tracef("could not find any IP address for interface %s", interfaceName)
    73  }
    74  
    75  // GetRoutableInterfaceIPAddresses returns GetInterfaceIPAddresses values for
    76  // the first non-loopback, non-point-to-point network interface on the host
    77  // that has an IP address.
    78  func GetRoutableInterfaceIPAddresses() (net.IP, net.IP, error) {
    79  
    80  	interfaces, err := net.Interfaces()
    81  	if err != nil {
    82  		return nil, nil, errors.Trace(err)
    83  	}
    84  
    85  	for i, in := range interfaces {
    86  		if (in.Flags&net.FlagUp == 0) ||
    87  			(in.Flags&(net.FlagLoopback|net.FlagPointToPoint)) != 0 {
    88  			continue
    89  		}
    90  		IPv4Address, IPv6Address, err := GetInterfaceIPAddresses(in.Name)
    91  		if err == nil {
    92  			return IPv4Address, IPv6Address, nil
    93  		} else if i == len(interfaces)-1 {
    94  			return nil, nil, errors.Trace(err)
    95  		}
    96  	}
    97  	return nil, nil, errors.TraceNew("no candidate interfaces found")
    98  }