CasperSecurity
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
POSIX implementation of local network interface enumeration.
"""
import socket
import sys
from ctypes import (
CDLL,
POINTER,
Structure,
c_char_p,
c_int,
c_ubyte,
c_uint8,
c_uint32,
c_ushort,
c_void_p,
cast,
pointer,
)
from ctypes.util import find_library
from socket import AF_INET, AF_INET6, inet_ntop
from typing import Any, List, Tuple
from twisted.python.compat import nativeString
libc = CDLL(find_library("c") or "")
if sys.platform.startswith("freebsd") or sys.platform == "darwin":
_sockaddrCommon: List[Tuple[str, Any]] = [
("sin_len", c_uint8),
("sin_family", c_uint8),
]
else:
_sockaddrCommon: List[Tuple[str, Any]] = [
("sin_family", c_ushort),
]
class in_addr(Structure):
_fields_ = [
("in_addr", c_ubyte * 4),
]
class in6_addr(Structure):
_fields_ = [
("in_addr", c_ubyte * 16),
]
class sockaddr(Structure):
_fields_ = _sockaddrCommon + [
("sin_port", c_ushort),
]
class sockaddr_in(Structure):
_fields_ = _sockaddrCommon + [
("sin_port", c_ushort),
("sin_addr", in_addr),
]
class sockaddr_in6(Structure):
_fields_ = _sockaddrCommon + [
("sin_port", c_ushort),
("sin_flowinfo", c_uint32),
("sin_addr", in6_addr),
]
class ifaddrs(Structure):
pass
ifaddrs_p = POINTER(ifaddrs)
ifaddrs._fields_ = [
("ifa_next", ifaddrs_p),
("ifa_name", c_char_p),
("ifa_flags", c_uint32),
("ifa_addr", POINTER(sockaddr)),
("ifa_netmask", POINTER(sockaddr)),
("ifa_dstaddr", POINTER(sockaddr)),
("ifa_data", c_void_p),
]
getifaddrs = libc.getifaddrs
getifaddrs.argtypes = [POINTER(ifaddrs_p)]
getifaddrs.restype = c_int
freeifaddrs = libc.freeifaddrs
freeifaddrs.argtypes = [ifaddrs_p]
def _maybeCleanupScopeIndex(family, packed):
"""
On FreeBSD, kill the embedded interface indices in link-local scoped
addresses.
@param family: The address family of the packed address - one of the
I{socket.AF_*} constants.
@param packed: The packed representation of the address (ie, the bytes of a
I{in_addr} field).
@type packed: L{bytes}
@return: The packed address with any FreeBSD-specific extra bits cleared.
@rtype: L{bytes}
@see: U{https://twistedmatrix.com/trac/ticket/6843}
@see: U{http://www.freebsd.org/doc/en/books/developers-handbook/ipv6.html#ipv6-scope-index}
@note: Indications are that the need for this will be gone in FreeBSD >=10.
"""
if sys.platform.startswith("freebsd") and packed[:2] == b"\xfe\x80":
return packed[:2] + b"\x00\x00" + packed[4:]
return packed
def _interfaces():
"""
Call C{getifaddrs(3)} and return a list of tuples of interface name, address
family, and human-readable address representing its results.
"""
ifaddrs = ifaddrs_p()
if getifaddrs(pointer(ifaddrs)) < 0:
raise OSError()
results = []
try:
while ifaddrs:
if ifaddrs[0].ifa_addr:
family = ifaddrs[0].ifa_addr[0].sin_family
if family == AF_INET:
addr = cast(ifaddrs[0].ifa_addr, POINTER(sockaddr_in))
elif family == AF_INET6:
addr = cast(ifaddrs[0].ifa_addr, POINTER(sockaddr_in6))
else:
addr = None
if addr:
packed = bytes(addr[0].sin_addr.in_addr[:])
packed = _maybeCleanupScopeIndex(family, packed)
results.append(
(ifaddrs[0].ifa_name, family, inet_ntop(family, packed))
)
ifaddrs = ifaddrs[0].ifa_next
finally:
freeifaddrs(ifaddrs)
return results
def posixGetLinkLocalIPv6Addresses():
"""
Return a list of strings in colon-hex format representing all the link local
IPv6 addresses available on the system, as reported by I{getifaddrs(3)}.
"""
retList = []
for (interface, family, address) in _interfaces():
interface = nativeString(interface)
address = nativeString(address)
if family == socket.AF_INET6 and address.startswith("fe80:"):
retList.append(f"{address}%{interface}")
return retList