host: Add tools for discovering hosts
parent
0f27bc502e
commit
d4dfb3cafd
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@ -0,0 +1,209 @@
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from __future__ import unicode_literals
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import socket
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import struct
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import subprocess
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try:
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long_ = long
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except NameError:
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long_ = int
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try:
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range_ = xrange
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except NameError:
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range_ = range
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class Neighbor(object):
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def __init__(self, ipaddr=None, macaddr=None):
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self.ipaddr = ipaddr
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self.macaddr = macaddr
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def __repr__(self):
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return str('{klass}({ipaddr!r}, {macaddr!r})'.format(
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klass=self.__class__.__name__,
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ipaddr=self.ipaddr,
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macaddr=self.macaddr,
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))
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class NeighborTable(object):
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def __init__(self):
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self.entries = []
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self.refresh()
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def __iter__(self):
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for n in self.entries:
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yield n
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def __getitem__(self, item):
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for n in self:
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if item in (n.ipaddr, n.macaddr):
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return n
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raise KeyError(item)
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def refresh(self):
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self.entries = []
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try:
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o = subprocess.check_output(['ip', 'neighbor', 'show'])
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except (OSError, subprocess.CalledProcessError):
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return
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for line in reversed(o.splitlines()):
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parts = line.strip().decode().split()
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try:
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i = parts[0]
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m = MacAddress(parts[4]).with_colons()
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except (IndexError, ValueError):
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continue
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self.entries.append(Neighbor(i, m))
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class MacAddress(object):
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def __init__(self, macaddr):
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if hasattr(macaddr, 'encode'):
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self.value = self.parse(macaddr)
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elif hasattr(macaddr, 'value'):
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self.value = macaddr.value
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else:
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self.value = long_(macaddr)
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def __str__(self):
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return str(self.with_colons())
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@classmethod
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def parse(cls, macaddr):
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if '.' in macaddr:
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parts = cls.parse_dotted(macaddr)
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elif ':' in macaddr:
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parts = cls.parse_colons(macaddr)
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elif '-' in macaddr:
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parts = cls.parse_hyphens(macaddr)
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else:
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parts = (macaddr[i:i+2] for i in range_(0, len(macaddr), 2))
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value = 0
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for part in parts:
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value <<= 8
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value += int(part, 16)
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return value
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@classmethod
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def parse_colons(cls, macaddr):
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return macaddr.split(':')
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@classmethod
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def parse_dotted(cls, macaddr):
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parts = macaddr.split('.')
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if len(parts) != 3:
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raise ValueError('Invalid MAC address {}'.format(macaddr))
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for part in parts:
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yield part[:2]
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yield part[2:]
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@classmethod
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def parse_hyphens(cls, macaddr):
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return macaddr.split('-')
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@property
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def _packed(self):
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return bytearray(struct.pack(str('>Q'), self.value))[2:]
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def with_colons(self):
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return ':'.join('{:02x}'.format(x) for x in self._packed)
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def with_dots(self):
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p = list(self._packed)
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parts = (p[i:i+2] for i in range_(0, len(p), 2))
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return '.'.join('{:04x}'.format((x << 8) + y) for x, y in parts)
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def with_hyphens(self):
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return '-'.join('{:02X}'.format(x) for x in self._packed)
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class Host(object):
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@staticmethod
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def ping(host, port=7):
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try:
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ai = socket.getaddrinfo(host, port, socket.AF_UNSPEC,
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socket.SOCK_DGRAM)
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except socket.gaierror:
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return
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for af, socktype, proto, __, sa in ai:
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sock = None
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try:
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sock = socket.socket(af, socktype, proto)
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sock.sendto(b'\x00', sa)
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except socket.error:
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return
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finally:
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if sock is not None:
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sock.close()
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@classmethod
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def discover(cls, hint):
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def try_mac():
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try:
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return cls.from_macaddr(hint)
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except ValueError:
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return None
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def try_name():
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try:
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return cls.from_hostname(hint)
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except ValueError:
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return None
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if ':' in hint:
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return try_mac() or try_name()
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else:
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return try_name() or try_mac()
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@classmethod
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def from_hostname(cls, value):
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try:
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ai = socket.getaddrinfo(value, None, 0, 0, 0, socket.AI_CANONNAME)
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except socket.gaierror as e:
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raise ValueError(str(e))
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ipaddr = None
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hostname = None
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for __, __, __, name, addr in ai:
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if addr[0] != '::1' and not addr[0].startswith('127.'):
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ipaddr = addr[0]
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if name and not name.startswith('localhost'):
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hostname = name
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if hostname and ipaddr:
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break
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if not ipaddr:
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return
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cls.ping(ipaddr)
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try:
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neighbor = NeighborTable()[ipaddr]
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except KeyError:
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return None
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host = cls()
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host.macaddr = neighbor.macaddr
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host.ipaddr = ipaddr
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host.hostname = hostname
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return host
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@classmethod
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def from_macaddr(cls, value):
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m = MacAddress(value)
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host = cls()
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host.macaddr = m.with_colons()
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try:
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neighbor = NeighborTable()[host.macaddr]
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except KeyError:
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pass
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else:
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host.ipaddr = neighbor.ipaddr
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try:
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ni = socket.getnameinfo((host.ipaddr, 0), 0)
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except socket.gaierror:
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pass
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else:
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host.hostname = ni[0]
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return host
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