get_interfaces.py

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#!/usr/bin/python
 
# Based on getifaddrs.py from pydlnadms [http://code.google.com/p/pydlnadms/].
# Only tested on Linux!
 
from socket import AF_INET, AF_INET6, inet_ntop
from ctypes import (
Structure, Union, POINTER,
pointer, get_errno, cast,
c_ushort, c_byte, c_void_p, c_char_p, c_uint, c_int, c_uint16, c_uint32
)
import ctypes.util
import ctypes
 
class struct_sockaddr(Structure):
        _fields_ = [
                ('sa_family', c_ushort),
                ('sa_data', c_byte * 14),]
 
class struct_sockaddr_in(Structure):
        _fields_ = [
                ('sin_family', c_ushort),
                ('sin_port', c_uint16),
                ('sin_addr', c_byte * 4)]
 
class struct_sockaddr_in6(Structure):
        _fields_ = [
                ('sin6_family', c_ushort),
                ('sin6_port', c_uint16),
                ('sin6_flowinfo', c_uint32),
                ('sin6_addr', c_byte * 16),
                ('sin6_scope_id', c_uint32)]
 
class union_ifa_ifu(Union):
        _fields_ = [
                ('ifu_broadaddr', POINTER(struct_sockaddr)),
                ('ifu_dstaddr', POINTER(struct_sockaddr)),]
 
class struct_ifaddrs(Structure):
        pass
struct_ifaddrs._fields_ = [
        ('ifa_next', POINTER(struct_ifaddrs)),
        ('ifa_name', c_char_p),
        ('ifa_flags', c_uint),
        ('ifa_addr', POINTER(struct_sockaddr)),
        ('ifa_netmask', POINTER(struct_sockaddr)),
        ('ifa_ifu', union_ifa_ifu),
        ('ifa_data', c_void_p),]
 
libc = ctypes.CDLL(ctypes.util.find_library('c'))
 
def ifap_iter(ifap):
        ifa = ifap.contents
        while True:
                yield ifa
                if not ifa.ifa_next:
                        break
                ifa = ifa.ifa_next.contents
 
def getfamaddr(sa):
        family = sa.sa_family
        addr = None
        if family == AF_INET:
                sa = cast(pointer(sa), POINTER(struct_sockaddr_in)).contents
                addr = inet_ntop(family, sa.sin_addr)
        elif family == AF_INET6:
                sa = cast(pointer(sa), POINTER(struct_sockaddr_in6)).contents
                addr = inet_ntop(family, sa.sin6_addr)
        return family, addr
 
class NetworkInterface(object):
        def __init__(self, name):
                self.name = name
                self.index = libc.if_nametoindex(name)
                self.addresses = {}
 
        def __str__(self):
                return "%s [index=%d, IPv4=%s, IPv6=%s]" % (
                        self.name, self.index,
                        self.addresses.get(AF_INET),
                        self.addresses.get(AF_INET6))
        
        def name(self):
                return self.name,
         
def get_network_interfaces():
        ifap = POINTER(struct_ifaddrs)()
        result = libc.getifaddrs(pointer(ifap))
        if result != 0:
                raise OSError(get_errno())
        del result
        try:
                retval = {}
                for ifa in ifap_iter(ifap):
                        name = ifa.ifa_name
                        i = retval.get(name)
                        if not i:
                                i = retval[name] = NetworkInterface(name)
                        family, addr = getfamaddr(ifa.ifa_addr.contents)
                        if addr:
                                i.addresses[family] = addr
                return retval.values()
        finally:
                libc.freeifaddrs(ifap)
 
if __name__ == '__main__':
        print [str(ni) for ni in get_network_interfaces()]