# # Netlink interface based on libnl # # Copyright (c) 2011 Thomas Graf # """netlink library based on libnl This module provides an interface to netlink sockets The module contains the following public classes: - Socket -- The netlink socket - Message -- The netlink message - Callback -- The netlink callback handler - Object -- Abstract object (based on struct nl_obect in libnl) used as base class for all object types which can be put into a Cache - Cache -- A collection of objects which are derived from the base class Object. Used for netlink protocols which maintain a list or tree of objects. - DumpParams -- The following exceptions are defined: - NetlinkError -- Base exception for all general purpose exceptions raised. - KernelError -- Raised when the kernel returns an error as response to a request. All other classes or functions in this module are considered implementation details. """ from __future__ import absolute_import from . import capi import sys import socket __all__ = [ 'Socket', 'Message', 'Callback', 'DumpParams', 'Object', 'Cache', 'KernelError', 'NetlinkError', ] __version__ = '0.1' # netlink protocols NETLINK_ROUTE = 0 # NETLINK_UNUSED = 1 NETLINK_USERSOCK = 2 NETLINK_FIREWALL = 3 NETLINK_INET_DIAG = 4 NETLINK_NFLOG = 5 NETLINK_XFRM = 6 NETLINK_SELINUX = 7 NETLINK_ISCSI = 8 NETLINK_AUDIT = 9 NETLINK_FIB_LOOKUP = 10 NETLINK_CONNECTOR = 11 NETLINK_NETFILTER = 12 NETLINK_IP6_FW = 13 NETLINK_DNRTMSG = 14 NETLINK_KOBJECT_UEVENT = 15 NETLINK_GENERIC = 16 NETLINK_SCSITRANSPORT = 18 NETLINK_ECRYPTFS = 19 NL_DONTPAD = 0 NL_AUTO_PORT = 0 NL_AUTO_SEQ = 0 NL_DUMP_LINE = 0 NL_DUMP_DETAILS = 1 NL_DUMP_STATS = 2 NLM_F_REQUEST = 1 NLM_F_MULTI = 2 NLM_F_ACK = 4 NLM_F_ECHO = 8 NLM_F_ROOT = 0x100 NLM_F_MATCH = 0x200 NLM_F_ATOMIC = 0x400 NLM_F_DUMP = NLM_F_ROOT | NLM_F_MATCH NLM_F_REPLACE = 0x100 NLM_F_EXCL = 0x200 NLM_F_CREATE = 0x400 NLM_F_APPEND = 0x800 class NetlinkError(Exception): def __init__(self, error): self._error = error self._msg = capi.nl_geterror(error) def __str__(self): return self._msg class KernelError(NetlinkError): def __str__(self): return 'Kernel returned: {0}'.format(self._msg) class ImmutableError(NetlinkError): def __init__(self, msg): self._msg = msg def __str__(self): return 'Immutable attribute: {0}'.format(self._msg) class Message(object): """Netlink message""" def __init__(self, size=0): if size == 0: self._msg = capi.nlmsg_alloc() else: self._msg = capi.nlmsg_alloc_size(size) if self._msg is None: raise Exception('Message allocation returned NULL') def __del__(self): capi.nlmsg_free(self._msg) def __len__(self): return capi.nlmsg_len(nlmsg_hdr(self._msg)) @property def protocol(self): return capi.nlmsg_get_proto(self._msg) @protocol.setter def protocol(self, value): capi.nlmsg_set_proto(self._msg, value) @property def maxSize(self): return capi.nlmsg_get_max_size(self._msg) @property def hdr(self): return capi.nlmsg_hdr(self._msg) @property def data(self): return capi.nlmsg_data(self._msg) @property def attrs(self): return capi.nlmsg_attrdata(self._msg) def send(self, sock): sock.send(self) class Callback(object): """Netlink callback""" def __init__(self, kind=capi.NL_CB_DEFAULT): if isinstance(kind, Callback): self._cb = capi.py_nl_cb_clone(kind._cb) else: self._cb = capi.nl_cb_alloc(kind) def __del__(self): capi.py_nl_cb_put(self._cb) def set_type(self, t, k, handler, obj): return capi.py_nl_cb_set(self._cb, t, k, handler, obj) def set_all(self, k, handler, obj): return capi.py_nl_cb_set_all(self._cb, k, handler, obj) def set_err(self, k, handler, obj): return capi.py_nl_cb_err(self._cb, k, handler, obj) def clone(self): return Callback(self) class Socket(object): """Netlink socket""" def __init__(self, cb=None): if isinstance(cb, Callback): self._sock = capi.nl_socket_alloc_cb(cb._cb) elif cb == None: self._sock = capi.nl_socket_alloc() else: raise Exception('\'cb\' parameter has wrong type') if self._sock is None: raise Exception('NULL pointer returned while allocating socket') def __del__(self): capi.nl_socket_free(self._sock) def __str__(self): return 'nlsock<{0}>'.format(self.local_port) @property def local_port(self): return capi.nl_socket_get_local_port(self._sock) @local_port.setter def local_port(self, value): capi.nl_socket_set_local_port(self._sock, int(value)) @property def peer_port(self): return capi.nl_socket_get_peer_port(self._sock) @peer_port.setter def peer_port(self, value): capi.nl_socket_set_peer_port(self._sock, int(value)) @property def peer_groups(self): return capi.nl_socket_get_peer_groups(self._sock) @peer_groups.setter def peer_groups(self, value): capi.nl_socket_set_peer_groups(self._sock, value) def set_bufsize(self, rx, tx): capi.nl_socket_set_buffer_size(self._sock, rx, tx) def connect(self, proto): capi.nl_connect(self._sock, proto) return self def disconnect(self): capi.nl_close(self._sock) def sendto(self, buf): ret = capi.nl_sendto(self._sock, buf, len(buf)) if ret < 0: raise Exception('Failed to send') else: return ret def send_auto_complete(self, msg): if not isinstance(msg, Message): raise Exception('must provide Message instance') ret = capi.nl_send_auto_complete(self._sock, msg._msg) if ret < 0: raise Exception('send_auto_complete failed: ret=%d' % ret) return ret def recvmsgs(self, recv_cb): if not isinstance(recv_cb, Callback): raise Exception('must provide Callback instance') ret = capi.nl_recvmsgs(self._sock, recv_cb._cb) if ret < 0: raise Exception('recvmsg failed: ret=%d' % ret) _sockets = {} def lookup_socket(protocol): try: sock = _sockets[protocol] except KeyError: sock = Socket() sock.connect(protocol) _sockets[protocol] = sock return sock class DumpParams(object): """Dumping parameters""" def __init__(self, type_=NL_DUMP_LINE): self._dp = capi.alloc_dump_params() if not self._dp: raise Exception('Unable to allocate struct nl_dump_params') self._dp.dp_type = type_ def __del__(self): capi.free_dump_params(self._dp) @property def type(self): return self._dp.dp_type @type.setter def type(self, value): self._dp.dp_type = value @property def prefix(self): return self._dp.dp_prefix @prefix.setter def prefix(self, value): self._dp.dp_prefix = value # underscore this to make sure it is deleted first upon module deletion _defaultDumpParams = DumpParams(NL_DUMP_LINE) class Object(object): """Cacheable object (base class)""" def __init__(self, obj_name, name, obj=None): self._obj_name = obj_name self._name = name self._modules = [] if not obj: obj = capi.object_alloc_name(self._obj_name) self._nl_object = obj # Create a clone which stores the original state to notice # modifications clone_obj = capi.nl_object_clone(self._nl_object) self._orig = self._obj2type(clone_obj) def __del__(self): if not self._nl_object: raise ValueError() capi.nl_object_put(self._nl_object) def __str__(self): if hasattr(self, 'format'): return self.format() else: return capi.nl_object_dump_buf(self._nl_object, 4096).rstrip() def _new_instance(self): raise NotImplementedError() def clone(self): """Clone object""" return self._new_instance(capi.nl_object_clone(self._nl_object)) def _module_lookup(self, path, constructor=None): """Lookup object specific module and load it Object implementations consisting of multiple types may offload some type specific code to separate modules which are loadable on demand, e.g. a VLAN link or a specific queueing discipline implementation. Loads the module `path` and calls the constructor if supplied or `module`.init() The constructor/init function typically assigns a new object covering the type specific implementation aspects to the new object, e.g. link.vlan = VLANLink() """ try: __import__(path) except ImportError: return module = sys.modules[path] if constructor: ret = getattr(module, constructor)(self) else: ret = module.init(self) if ret: self._modules.append(ret) def _module_brief(self): ret = '' for module in self._modules: if hasattr(module, 'brief'): ret += module.brief() return ret def dump(self, params=None): """Dump object as human readable text""" if params is None: params = _defaultDumpParams capi.nl_object_dump(self._nl_object, params._dp) @property def mark(self): return bool(capi.nl_object_is_marked(self._nl_object)) @mark.setter def mark(self, value): if value: capi.nl_object_mark(self._nl_object) else: capi.nl_object_unmark(self._nl_object) @property def shared(self): return capi.nl_object_shared(self._nl_object) != 0 @property def attrs(self): attr_list = capi.nl_object_attr_list(self._nl_object, 1024) return attr_list[0].split() @property def refcnt(self): return capi.nl_object_get_refcnt(self._nl_object) # this method resolves multiple levels of sub types to allow # accessing properties of subclass/subtypes (e.g. link.vlan.id) def _resolve(self, attr): obj = self l = attr.split('.') while len(l) > 1: obj = getattr(obj, l.pop(0)) return (obj, l.pop(0)) def _setattr(self, attr, val): obj, attr = self._resolve(attr) return setattr(obj, attr, val) def _hasattr(self, attr): obj, attr = self._resolve(attr) return hasattr(obj, attr) class ObjIterator(object): def __init__(self, cache, obj): self._cache = cache self._nl_object = None if not obj: self._end = 1 else: capi.nl_object_get(obj) self._nl_object = obj self._first = 1 self._end = 0 def __del__(self): if self._nl_object: capi.nl_object_put(self._nl_object) def __iter__(self): return self def get_next(self): return capi.nl_cache_get_next(self._nl_object) def next(self): return self.__next__() def __next__(self): if self._end: raise StopIteration() if self._first: ret = self._nl_object self._first = 0 else: ret = self.get_next() if not ret: self._end = 1 raise StopIteration() # return ref of previous element and acquire ref of current # element to have object stay around until we fetched the # next ptr capi.nl_object_put(self._nl_object) capi.nl_object_get(ret) self._nl_object = ret # reference used inside object capi.nl_object_get(ret) return self._cache._new_object(ret) class ReverseObjIterator(ObjIterator): def get_next(self): return capi.nl_cache_get_prev(self._nl_object) class Cache(object): """Collection of netlink objects""" def __init__(self): if self.__class__ is Cache: raise NotImplementedError() self.arg1 = None self.arg2 = None def __del__(self): capi.nl_cache_free(self._nl_cache) def __len__(self): return capi.nl_cache_nitems(self._nl_cache) def __iter__(self): obj = capi.nl_cache_get_first(self._nl_cache) return ObjIterator(self, obj) def __reversed__(self): obj = capi.nl_cache_get_last(self._nl_cache) return ReverseObjIterator(self, obj) def __contains__(self, item): obj = capi.nl_cache_search(self._nl_cache, item._nl_object) if obj is None: return False else: capi.nl_object_put(obj) return True # called by sub classes to allocate type specific caches by name @staticmethod def _alloc_cache_name(name): return capi.alloc_cache_name(name) # implemented by sub classes, must return new instasnce of cacheable # object @staticmethod def _new_object(obj): raise NotImplementedError() # implemented by sub classes, must return instance of sub class def _new_cache(self, cache): raise NotImplementedError() def subset(self, filter_): """Return new cache containing subset of cache Cretes a new cache containing all objects which match the specified filter. """ if not filter_: raise ValueError() c = capi.nl_cache_subset(self._nl_cache, filter_._nl_object) return self._new_cache(cache=c) def dump(self, params=None, filter_=None): """Dump (print) cache as human readable text""" if not params: params = _defaultDumpParams if filter_: filter_ = filter_._nl_object capi.nl_cache_dump_filter(self._nl_cache, params._dp, filter_) def clear(self): """Remove all cache entries""" capi.nl_cache_clear(self._nl_cache) # Called by sub classes to set first cache argument def _set_arg1(self, arg): self.arg1 = arg capi.nl_cache_set_arg1(self._nl_cache, arg) # Called by sub classes to set second cache argument def _set_arg2(self, arg): self.arg2 = arg capi.nl_cache_set_arg2(self._nl_cache, arg) def refill(self, socket=None): """Clear cache and refill it""" if socket is None: socket = lookup_socket(self._protocol) capi.nl_cache_refill(socket._sock, self._nl_cache) return self def resync(self, socket=None, cb=None, args=None): """Synchronize cache with content in kernel""" if socket is None: socket = lookup_socket(self._protocol) capi.nl_cache_resync(socket._sock, self._nl_cache, cb, args) def provide(self): """Provide this cache to others Caches which have been "provided" are made available to other users (of the same application context) which "require" it. F.e. a link cache is generally provided to allow others to translate interface indexes to link names """ capi.nl_cache_mngt_provide(self._nl_cache) def unprovide(self): """Unprovide this cache No longer make the cache available to others. If the cache has been handed out already, that reference will still be valid. """ capi.nl_cache_mngt_unprovide(self._nl_cache) # Cache Manager (Work in Progress) NL_AUTO_PROVIDE = 1 class CacheManager(object): def __init__(self, protocol, flags=None): self._sock = Socket() self._sock.connect(protocol) if not flags: flags = NL_AUTO_PROVIDE self._mngr = capi.cache_mngr_alloc(self._sock._sock, protocol, flags) def __del__(self): if self._sock: self._sock.disconnect() if self._mngr: capi.nl_cache_mngr_free(self._mngr) def add(self, name): capi.cache_mngr_add(self._mngr, name, None, None) class AddressFamily(object): """Address family representation af = AddressFamily('inet6') # raises: # - ValueError if family name is not known # - TypeError if invalid type is specified for family print af # => 'inet6' (string representation) print int(af) # => 10 (numeric representation) print repr(af) # => AddressFamily('inet6') """ def __init__(self, family=socket.AF_UNSPEC): if isinstance(family, str): family = capi.nl_str2af(family) if family < 0: raise ValueError('Unknown family name') elif not isinstance(family, int): raise TypeError() self._family = family def __str__(self): return capi.nl_af2str(self._family, 32)[0] def __int__(self): return self._family def __repr__(self): return 'AddressFamily({0!r})'.format(str(self)) class AbstractAddress(object): """Abstract address object addr = AbstractAddress('127.0.0.1/8') print addr # => '127.0.0.1/8' print addr.prefixlen # => '8' print addr.family # => 'inet' print len(addr) # => '4' (32bit ipv4 address) a = AbstractAddress('10.0.0.1/24') b = AbstractAddress('10.0.0.2/24') print a == b # => False """ def __init__(self, addr): self._nl_addr = None if isinstance(addr, str): # returns None on success I guess # TO CORRECT addr = capi.addr_parse(addr, socket.AF_UNSPEC) if addr is None: raise ValueError('Invalid address format') elif addr: capi.nl_addr_get(addr) self._nl_addr = addr def __del__(self): if self._nl_addr: capi.nl_addr_put(self._nl_addr) def __cmp__(self, other): if isinstance(other, str): other = AbstractAddress(other) diff = self.prefixlen - other.prefixlen if diff == 0: diff = capi.nl_addr_cmp(self._nl_addr, other._nl_addr) return diff def contains(self, item): diff = int(self.family) - int(item.family) if diff: return False if item.prefixlen < self.prefixlen: return False diff = capi.nl_addr_cmp_prefix(self._nl_addr, item._nl_addr) return diff == 0 def __nonzero__(self): if self._nl_addr: return not capi.nl_addr_iszero(self._nl_addr) else: return False def __len__(self): if self._nl_addr: return capi.nl_addr_get_len(self._nl_addr) else: return 0 def __str__(self): if self._nl_addr: return capi.nl_addr2str(self._nl_addr, 64)[0] else: return 'none' @property def shared(self): """True if address is shared (multiple users)""" if self._nl_addr: return capi.nl_addr_shared(self._nl_addr) != 0 else: return False @property def prefixlen(self): """Length of prefix (number of bits)""" if self._nl_addr: return capi.nl_addr_get_prefixlen(self._nl_addr) else: return 0 @prefixlen.setter def prefixlen(self, value): if not self._nl_addr: raise TypeError() capi.nl_addr_set_prefixlen(self._nl_addr, int(value)) @property def family(self): """Address family""" f = 0 if self._nl_addr: f = capi.nl_addr_get_family(self._nl_addr) return AddressFamily(f) @family.setter def family(self, value): if not self._nl_addr: raise TypeError() if not isinstance(value, AddressFamily): value = AddressFamily(value) capi.nl_addr_set_family(self._nl_addr, int(value)) # keyword: # type = { int | str } # immutable = { True | False } # fmt = func (formatting function) # title = string def nlattr(**kwds): """netlink object attribute decorator decorator used to mark mutable and immutable properties of netlink objects. All properties marked as such are regarded to be accessable. @property @netlink.nlattr(type=int) def my_attr(self): return self._my_attr """ def wrap_fn(func): func.formatinfo = kwds return func return wrap_fn