def macaddr_from_ipv4(ipv4):
"""
Given @ipv4, returns the @macaddr or None if unknown / lookup failed, etc.
"""
if not is_ipv4_address_valid(ipv4):
return None
ipv4 = normalize_ipv4_address(ipv4)
by_ipv4 = load(DHCPD_LEASES_FILENAME)[0]
if ipv4 not in by_ipv4:
return None
else:
return by_ipv4[ipv4].macaddr
def load(filename):
"""
Load a dhcpd.leases file.
WARNING: The parsing is _NOT_ done the same way dhcpd does it, for
simplicity reasons. Anyway it should work. Maybe.
Returns (by_ipv4, by_macaddr) where both are dictionaries in which values
are LeaseEntry instances and keys are IPv4 in @by_ipv4 and mac address in
@by_macaddr.
TODO: check validity periods
"""
by_ipv4 = {}
by_macaddr = {}
state = NOWHERE
for line in file(filename):
line = line.rstrip()
fully_stripped_line = line.lstrip()
if (not fully_stripped_line) or fully_stripped_line[0] == '#':
continue
if state is NOWHERE:
if line.startswith("lease "):
lease_header = line.split()
if len(lease_header) == 3 and is_ipv4_address_valid(lease_header[1]) and lease_header[2] == "{":
current = LeaseEntry(lease_header[1])
state = LEASE
else:
# XXX log that our parser is too dumb to correctly parse the file
state = UNKNOWN
elif state is UNKNOWN:
if fully_stripped_line == '}':
state = NOWHERE
else:
pass # XXX log
elif state is LEASE:
for start, method in LEASE_ATTRS:
remain = match_remain_and_strip_semicolon(fully_stripped_line, start)
if remain is not None:
method(current, remain)
break
else:
if fully_stripped_line == '}':
if current.ipv4 in by_ipv4:
macaddr_to_rm = by_ipv4[current.ipv4].macaddr
del by_ipv4[current.ipv4]
del by_macaddr[macaddr_to_rm]
if is_mac_address_valid(getattr(current, 'macaddr', "")) \
and getattr(current, 'binding_state', None) == 'active':
if current.macaddr in by_macaddr:
ipv4_to_rm = by_macaddr[current.macaddr].ipv4
del by_ipv4[ipv4_to_rm]
del by_macaddr[current.macaddr]
by_ipv4[current.ipv4] = current
by_macaddr[current.macaddr] = current
else:
# log that this lease entry is useless for us if without a mac address or binding state isn't active
pass
del current
state = NOWHERE
else:
# XXX count number of unknown lease lines
pass
return by_ipv4, by_macaddr
def is_ipv4_netmask_valid(netmask):
"Verify if it is a valid netmask."
return network.is_ipv4_address_valid(netmask) \
and network.plausible_netmask(network.parse_ipv4(netmask))
