twisted/internet/test/_posixifaces.py

   1 # Copyright (c) Twisted Matrix Laboratories.
   2 # See LICENSE for details.
   3
   4 """
   5 POSIX implementation of local network interface enumeration.
   6 """
   7
   8 import sys, socket
   9
  10 from socket import AF_INET, AF_INET6, inet_ntop
  11 from ctypes import (
  12     CDLL, POINTER, Structure, c_char_p, c_ushort, c_int,
  13     c_uint32, c_uint8, c_void_p, c_ubyte, pointer, cast)
  14 from ctypes.util import find_library
  15
  16 libc = CDLL(find_library("c"))
  17
  18 if sys.platform == 'darwin':
  19     _sockaddrCommon = [
  20         ("sin_len", c_uint8),
  21         ("sin_family", c_uint8),
  22         ]
  23 else:
  24     _sockaddrCommon = [
  25         ("sin_family", c_ushort),
  26         ]
  27
  28
  29
  30 class in_addr(Structure):
  31     _fields_ = [
  32         ("in_addr", c_ubyte * 4),
  33         ]
  34
  35
  36
  37 class in6_addr(Structure):
  38     _fields_ = [
  39         ("in_addr", c_ubyte * 16),
  40         ]
  41
  42
  43
  44 class sockaddr(Structure):
  45     _fields_ = _sockaddrCommon + [
  46         ("sin_port", c_ushort),
  47         ]
  48
  49
  50
  51 class sockaddr_in(Structure):
  52     _fields_ = _sockaddrCommon + [
  53         ("sin_port", c_ushort),
  54         ("sin_addr", in_addr),
  55         ]
  56
  57
  58
  59 class sockaddr_in6(Structure):
  60     _fields_ = _sockaddrCommon + [
  61         ("sin_port", c_ushort),
  62         ("sin_flowinfo", c_uint32),
  63         ("sin_addr", in6_addr),
  64         ]
  65
  66
  67
  68 class ifaddrs(Structure):
  69     pass
  70
  71 ifaddrs_p = POINTER(ifaddrs)
  72 ifaddrs._fields_ = [
  73     ('ifa_next', ifaddrs_p),
  74     ('ifa_name', c_char_p),
  75     ('ifa_flags', c_uint32),
  76     ('ifa_addr', POINTER(sockaddr)),
  77     ('ifa_netmask', POINTER(sockaddr)),
  78     ('ifa_dstaddr', POINTER(sockaddr)),
  79     ('ifa_data', c_void_p)]
  80
  81 getifaddrs = libc.getifaddrs
  82 getifaddrs.argtypes = [POINTER(ifaddrs_p)]
  83 getifaddrs.restype = c_int
  84
  85 freeifaddrs = libc.freeifaddrs
  86 freeifaddrs.argtypes = [ifaddrs_p]
  87
  88 def _interfaces():
  89     """
  90     Call C{getifaddrs(3)} and return a list of tuples of interface name, address
  91     family, and human-readable address representing its results.
  92     """
  93     ifaddrs = ifaddrs_p()
  94     if getifaddrs(pointer(ifaddrs)) < 0:
  95         raise OSError()
  96     results = []
  97     try:
  98         while ifaddrs:
  99             if ifaddrs[0].ifa_addr:
 100                 family = ifaddrs[0].ifa_addr[0].sin_family
 101                 if family == AF_INET:
 102                     addr = cast(ifaddrs[0].ifa_addr, POINTER(sockaddr_in))
 103                 elif family == AF_INET6:
 104                     addr = cast(ifaddrs[0].ifa_addr, POINTER(sockaddr_in6))
 105                 else:
 106                     addr = None
 107
 108                 if addr:
 109                     packed = ''.join(map(chr, addr[0].sin_addr.in_addr[:]))
 110                     results.append((
 111                             ifaddrs[0].ifa_name,
 112                             family,
 113                             inet_ntop(family, packed)))
 114
 115             ifaddrs = ifaddrs[0].ifa_next
 116     finally:
 117         freeifaddrs(ifaddrs)
 118     return results
 119
 120
 121
 122 def posixGetLinkLocalIPv6Addresses():
 123     """
 124     Return a list of strings in colon-hex format representing all the link local
 125     IPv6 addresses available on the system, as reported by I{getifaddrs(3)}.
 126     """
 127     retList = []
 128     for (interface, family, address) in _interfaces():
 129         if family == socket.AF_INET6 and address.startswith('fe80:'):
 130             retList.append('%s%%%s' % (address, interface))
 131     return retList