ironic-python-agent/ironic_python_agent/netutils.py
Sam Betts 14ac444f7c [LLDP] Skip NICs that say they are ready but are unreadable.
While listening for LLDP packets, if one of the sockets marks itself as
ready to read then our code will try to read data from that socket, but
if something goes wrong while reading that data then it causes IPA to
raise out of the loop skipping any other of the other NICs which might
have worked. This patch adds code to catch and LOG any exception that is
raised while we are trying to read data from one of the sockets so that
we can proceed to process all the NICs.

Change-Id: I8546097f5ae23755a5fdb448902007a2d823b7bf
Closes-Bug: #1665025
(cherry picked from commit b536fbba61)
2018-05-28 08:36:25 +00:00

236 lines
8.3 KiB
Python

# Copyright 2014 Rackspace, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import ctypes
import fcntl
import select
import socket
import struct
import sys
import netifaces
from oslo_config import cfg
from oslo_log import log as logging
from oslo_utils import netutils
LOG = logging.getLogger(__name__)
CONF = cfg.CONF
LLDP_ETHERTYPE = 0x88cc
IFF_PROMISC = 0x100
SIOCGIFFLAGS = 0x8913
SIOCSIFFLAGS = 0x8914
INFINIBAND_ADDR_LEN = 59
class ifreq(ctypes.Structure):
"""Class for setting flags on a socket."""
_fields_ = [("ifr_ifrn", ctypes.c_char * 16),
("ifr_flags", ctypes.c_short)]
class RawPromiscuousSockets(object):
def __init__(self, interface_names, protocol):
"""Initialize context manager.
:param interface_names: a list of interface names to bind to
:param protocol: the protocol to listen for
:returns: A list of tuple of (interface_name, bound_socket), or [] if
there is an exception binding or putting the sockets in
promiscuous mode
"""
if not interface_names:
raise ValueError('interface_names must be a non-empty list of '
'network interface names to bind to.')
self.protocol = protocol
# A 3-tuple of (interface_name, socket, ifreq object)
self.interfaces = [(name, self._get_socket(), ifreq())
for name in interface_names]
def __enter__(self):
for interface_name, sock, ifr in self.interfaces:
LOG.info('Interface %s entering promiscuous mode to capture ',
interface_name)
try:
ifr.ifr_ifrn = interface_name.encode()
# Get current flags
fcntl.ioctl(sock.fileno(), SIOCGIFFLAGS, ifr) # G for Get
# bitwise or the flags with promiscuous mode, set the new flags
ifr.ifr_flags |= IFF_PROMISC
fcntl.ioctl(sock.fileno(), SIOCSIFFLAGS, ifr) # S for Set
# Bind the socket so it can be used
LOG.debug('Binding interface %(interface)s for protocol '
'%(proto)s', {'interface': interface_name,
'proto': self.protocol})
sock.bind((interface_name, self.protocol))
except Exception:
LOG.error('Failed to open all RawPromiscuousSockets, '
'attempting to close any opened sockets.')
self.__exit__(*sys.exc_info())
raise
# No need to return each interfaces ifreq.
return [(sock[0], sock[1]) for sock in self.interfaces]
def __exit__(self, exception_type, exception_val, trace):
for name, sock, ifr in self.interfaces:
# bitwise or with the opposite of promiscuous mode to remove
ifr.ifr_flags &= ~IFF_PROMISC
try:
fcntl.ioctl(sock.fileno(), SIOCSIFFLAGS, ifr)
sock.close()
except Exception:
LOG.exception('Failed to close raw socket for interface %s',
name)
def _get_socket(self):
return socket.socket(socket.AF_PACKET, socket.SOCK_RAW, self.protocol)
def get_lldp_info(interface_names):
"""Get LLDP info from the switch(es) the agent is connected to.
Listens on either a single or all interfaces for LLDP packets, then
parses them. If no LLDP packets are received before lldp_timeout,
returns a dictionary in the form {'interface': [],...}.
:param interface_names: The interface to listen for packets on. If
None, will listen on each interface.
:return: A dictionary in the form
{'interface': [(lldp_type, lldp_data)],...}
"""
with RawPromiscuousSockets(interface_names, LLDP_ETHERTYPE) as interfaces:
try:
return _get_lldp_info(interfaces)
except Exception as e:
LOG.exception('Error while getting LLDP info: %s', str(e))
raise
def _parse_tlv(buff):
"""Iterate over a buffer and generate structured TLV data.
:param buff: An ethernet packet with the header trimmed off (first
14 bytes)
"""
lldp_info = []
while len(buff) >= 2:
# TLV structure: type (7 bits), length (9 bits), val (0-511 bytes)
tlvhdr = struct.unpack('!H', buff[:2])[0]
tlvtype = (tlvhdr & 0xfe00) >> 9
tlvlen = (tlvhdr & 0x01ff)
tlvdata = buff[2:tlvlen + 2]
buff = buff[tlvlen + 2:]
lldp_info.append((tlvtype, tlvdata))
if buff:
LOG.warning("Trailing byte received in an LLDP package: %r", buff)
return lldp_info
def _receive_lldp_packets(sock):
"""Receive LLDP packets and process them.
:param sock: A bound socket
:return: A list of tuples in the form (lldp_type, lldp_data)
"""
pkt = sock.recv(1600)
# Filter invalid packets
if not pkt or len(pkt) < 14:
return []
# Skip header (dst MAC, src MAC, ethertype)
pkt = pkt[14:]
return _parse_tlv(pkt)
def _get_lldp_info(interfaces):
"""Wait for packets on each socket, parse the received LLDP packets."""
LOG.debug('Getting LLDP info for interfaces %s', interfaces)
lldp_info = {}
if not interfaces:
return {}
while interfaces:
LOG.info('Waiting on LLDP info for interfaces: %(interfaces)s, '
'timeout: %(timeout)s', {'interfaces': interfaces,
'timeout': CONF.lldp_timeout})
socks = [interface[1] for interface in interfaces]
# rlist is a list of sockets ready for reading
rlist, _, _ = select.select(socks, [], [], CONF.lldp_timeout)
if not rlist:
# Empty read list means timeout on all interfaces
LOG.warning('LLDP timed out, remaining interfaces: %s',
interfaces)
break
for s in rlist:
# Find interface name matching socket ready for read
# Create a copy of interfaces to avoid deleting while iterating.
for index, interface in enumerate(list(interfaces)):
if s == interface[1]:
try:
lldp_info[interface[0]] = _receive_lldp_packets(s)
except socket.error:
LOG.exception('Socket for network interface %s said '
'that it was ready to read we were '
'unable to read from the socket while '
'trying to get LLDP packet. Skipping '
'this network interface.', interface[0])
else:
LOG.info('Found LLDP info for interface: %s',
interface[0])
# Remove interface from the list, only need one packet
del interfaces[index]
# Add any interfaces that didn't get a packet as empty lists
for name, _sock in interfaces:
lldp_info[name] = []
return lldp_info
def get_ipv4_addr(interface_id):
try:
addrs = netifaces.ifaddresses(interface_id)
return addrs[netifaces.AF_INET][0]['addr']
except (ValueError, IndexError, KeyError):
# No default IPv4 address found
return None
def interface_has_carrier(interface_name):
path = '/sys/class/net/{}/carrier'.format(interface_name)
try:
with open(path, 'rt') as fp:
return fp.read().strip() == '1'
except EnvironmentError:
LOG.debug('No carrier information for interface %s',
interface_name)
return False
def wrap_ipv6(ip):
if netutils.is_valid_ipv6(ip):
return "[%s]" % ip
return ip
def get_wildcard_address():
if netutils.is_ipv6_enabled():
return "::"
return "0.0.0.0"