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util.py
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util.py
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"Utility functions for Mininet."
from time import sleep
from resource import getrlimit, setrlimit, RLIMIT_NPROC, RLIMIT_NOFILE
from select import poll, POLLIN, POLLHUP
from subprocess import call, check_call, Popen, PIPE, STDOUT
import re
from fcntl import fcntl, F_GETFL, F_SETFL
from os import O_NONBLOCK
import os
from functools import partial
from mininet.log import output, info, error, warn, debug
# Command execution support
def run(cmd):
"""Simple interface to subprocess.call()
cmd: list of command params"""
return call(cmd.split(' '))
def checkRun(cmd):
"""Simple interface to subprocess.check_call()
cmd: list of command params"""
return check_call(cmd.split(' '))
# pylint doesn't understand explicit type checking
# pylint: disable=maybe-no-member
def oldQuietRun(*cmd):
"""Run a command, routing stderr to stdout, and return the output.
cmd: list of command params"""
if len(cmd) == 1:
cmd = cmd[ 0 ]
if isinstance(cmd, str):
cmd = cmd.split(' ')
popen = Popen(cmd, stdout=PIPE, stderr=STDOUT)
# We can't use Popen.communicate() because it uses
# select(), which can't handle
# high file descriptor numbers! poll() can, however.
out = ''
readable = poll()
readable.register(popen.stdout)
while True:
while readable.poll():
data = popen.stdout.read(1024)
if len(data) == 0:
break
out += data
popen.poll()
if popen.returncode is not None:
break
return out
# This is a bit complicated, but it enables us to
# monitor command output as it is happening
# pylint: disable=too-many-branches
def errRun(*cmd, **kwargs):
"""Run a command and return stdout, stderr and return code
cmd: string or list of command and args
stderr: STDOUT to merge stderr with stdout
shell: run command using shell
echo: monitor output to console"""
# By default we separate stderr, don't run in a shell, and don't echo
stderr = kwargs.get('stderr', PIPE)
shell = kwargs.get('shell', False)
echo = kwargs.get('echo', False)
if echo:
# cmd goes to stderr, output goes to stdout
info(cmd, '\n')
if len(cmd) == 1:
cmd = cmd[ 0 ]
# Allow passing in a list or a string
if isinstance(cmd, str) and not shell:
cmd = cmd.split(' ')
cmd = [ str(arg) for arg in cmd ]
elif isinstance(cmd, list) and shell:
cmd = " ".join(arg for arg in cmd)
debug('*** errRun:', cmd, '\n')
popen = Popen(cmd, stdout=PIPE, stderr=stderr, shell=shell)
# We use poll() because select() doesn't work with large fd numbers,
# and thus communicate() doesn't work either
out, err = '', ''
poller = poll()
poller.register(popen.stdout, POLLIN)
fdtofile = { popen.stdout.fileno(): popen.stdout }
outDone, errDone = False, True
if popen.stderr:
fdtofile[ popen.stderr.fileno() ] = popen.stderr
poller.register(popen.stderr, POLLIN)
errDone = False
while not outDone or not errDone:
readable = poller.poll()
for fd, event in readable:
f = fdtofile[ fd ]
if event & POLLIN:
data = f.read(1024)
if echo:
output(data)
if f == popen.stdout:
out += data
if data == '':
outDone = True
elif f == popen.stderr:
err += data
if data == '':
errDone = True
else: # POLLHUP or something unexpected
if f == popen.stdout:
outDone = True
elif f == popen.stderr:
errDone = True
poller.unregister(fd)
returncode = popen.wait()
debug(out, err, returncode)
return out, err, returncode
# pylint: enable=too-many-branches
def errFail(*cmd, **kwargs):
"Run a command using errRun and raise exception on nonzero exit"
out, err, ret = errRun(*cmd, **kwargs)
if ret:
raise Exception("errFail: %s failed with return code %s: %s"
% (cmd, ret, err))
return out, err, ret
def quietRun(cmd, **kwargs):
"Run a command and return merged stdout and stderr"
return errRun(cmd, stderr=STDOUT, **kwargs)[ 0 ]
# pylint: enable=maybe-no-member
def isShellBuiltin(cmd):
"Return True if cmd is a bash builtin."
if isShellBuiltin.builtIns is None:
isShellBuiltin.builtIns = quietRun('bash -c enable')
space = cmd.find(' ')
if space > 0:
cmd = cmd[ :space]
return cmd in isShellBuiltin.builtIns
isShellBuiltin.builtIns = None
# Interface management
#
# Interfaces are managed as strings which are simply the
# interface names, of the form 'nodeN-ethM'.
#
# To connect nodes, we create a pair of veth interfaces, and then place them
# in the pair of nodes that we want to communicate. We then update the node's
# list of interfaces and connectivity map.
#
# For the kernel datapath, switch interfaces
# live in the root namespace and thus do not have to be
# explicitly moved.
def makeIntfPair(intf1, intf2, addr1=None, addr2=None, node1=None, node2=None,
deleteIntfs=True, runCmd=None):
"""Make a veth pair connnecting new interfaces intf1 and intf2
intf1: name for interface 1
intf2: name for interface 2
addr1: MAC address for interface 1 (optional)
addr2: MAC address for interface 2 (optional)
node1: home node for interface 1 (optional)
node2: home node for interface 2 (optional)
deleteIntfs: delete intfs before creating them
runCmd: function to run shell commands (quietRun)
raises Exception on failure"""
if not runCmd:
runCmd = quietRun if not node1 else node1.cmd
runCmd2 = quietRun if not node2 else node2.cmd
if deleteIntfs:
# Delete any old interfaces with the same names
runCmd('ip link del ' + intf1)
runCmd2('ip link del ' + intf2)
# Create new pair
netns = 1 if not node2 else node2.pid
cmdOutput = ''
if addr1 is None and addr2 is None:
cmdOutput = runCmd('ip link add name %s '
'type veth peer name %s '
'netns %s' % (intf1, intf2, netns))
else:
cmdOutput = runCmd('ip link add name %s '
'address %s '
'type veth peer name %s '
'address %s '
'netns %s' %
(intf1, addr1, intf2, addr2, netns))
if cmdOutput:
raise Exception("Error creating interface pair (%s,%s): %s " %
(intf1, intf2, cmdOutput))
def retry(retries, delaySecs, fn, *args, **keywords):
"""Try something several times before giving up.
n: number of times to retry
delaySecs: wait this long between tries
fn: function to call
args: args to apply to function call"""
tries = 0
while not fn(*args, **keywords) and tries < retries:
sleep(delaySecs)
tries += 1
if tries >= retries:
error("*** gave up after %i retries\n" % tries)
exit(1)
def moveIntfNoRetry(intf, dstNode, printError=False):
"""Move interface to node, without retrying.
intf: string, interface
dstNode: destination Node
printError: if true, print error"""
if (dstNode.type == 'station' or dstNode.type == 'vehicle'
or dstNode.type == 'ap') and 'eth' not in str(intf):
if dstNode.type == 'station' or dstNode.type == 'vehicle':
return True
else:
intf = str(intf)
cmd = 'ip link set %s netns %s' % (intf, dstNode.pid)
cmdOutput = quietRun(cmd)
# If ip link set does not produce any output, then we can assume
# that the link has been moved successfully.
if cmdOutput:
if printError:
error('*** Error: moveIntf: ' + intf +
' not successfully moved to ' + dstNode.name + ':\n',
cmdOutput)
return False
return True
def moveIntf(intf, dstNode, printError=True,
retries=3, delaySecs=0.001):
"""Move interface to node, retrying on failure.
intf: string, interface
dstNode: destination Node
printError: if true, print error"""
if dstNode.type != 'ap':
retry(retries, delaySecs, moveIntfNoRetry, intf, dstNode,
printError=printError)
# Support for dumping network
def dumpNodeConnections(nodes):
"Dump connections to/from nodes."
def dumpConnections(node):
"Helper function: dump connections to node"
for intf in node.intfList():
output(' %s:' % intf)
if intf.link:
intfs = [ intf.link.intf1, intf.link.intf2 ]
intfs.remove(intf)
output(intfs[ 0 ])
else:
output(' ')
for node in nodes:
output(node.name)
dumpConnections(node)
output('\n')
def dumpNetConnections(net):
"Dump connections in network"
nodes = net.controllers + net.switches + net.hosts
dumpNodeConnections(nodes)
def dumpPorts(switches):
"dump interface to openflow port mappings for each switch"
for switch in switches:
output('%s ' % switch.name)
for intf in switch.intfList():
port = switch.ports[ intf ]
output('%s:%d ' % (intf, port))
output('\n')
# IP and Mac address formatting and parsing
def _colonHex(val, bytecount):
"""Generate colon-hex string.
val: input as unsigned int
bytecount: number of bytes to convert
returns: chStr colon-hex string"""
pieces = []
for i in range(bytecount - 1, -1, -1):
piece = ((0xff << (i * 8)) & val) >> (i * 8)
pieces.append('%02x' % piece)
chStr = ':'.join(pieces)
return chStr
def macColonHex(mac):
"""Generate MAC colon-hex string from unsigned int.
mac: MAC address as unsigned int
returns: macStr MAC colon-hex string"""
return _colonHex(mac, 6)
def ipStr(ip):
"""Generate IP address string from an unsigned int.
ip: unsigned int of form w << 24 | x << 16 | y << 8 | z
returns: ip address string w.x.y.z"""
w = (ip >> 24) & 0xff
x = (ip >> 16) & 0xff
y = (ip >> 8) & 0xff
z = ip & 0xff
return "%i.%i.%i.%i" % (w, x, y, z)
def ipNum(w, x, y, z):
"""Generate unsigned int from components of IP address
returns: w << 24 | x << 16 | y << 8 | z"""
return (w << 24) | (x << 16) | (y << 8) | z
def ipAdd(i, prefixLen=8, ipBaseNum=0x0a000000):
"""Return IP address string from ints
i: int to be added to ipbase
prefixLen: optional IP prefix length
ipBaseNum: option base IP address as int
returns IP address as string"""
imax = 0xffffffff >> prefixLen
assert i <= imax, 'Not enough IP addresses in the subnet'
mask = 0xffffffff ^ imax
ipnum = (ipBaseNum & mask) + i
return ipStr(ipnum)
def ipParse(ip):
"Parse an IP address and return an unsigned int."
args = [ int(arg) for arg in ip.split('.') ]
while len(args) < 4:
args.append(0)
return ipNum(*args)
def netParse(ipstr):
"""Parse an IP network specification, returning
address and prefix len as unsigned ints"""
prefixLen = 0
if '/' in ipstr:
ip, pf = ipstr.split('/')
prefixLen = int(pf)
# if no prefix is specified, set the prefix to 24
else:
ip = ipstr
prefixLen = 24
return ipParse(ip), prefixLen
def checkInt(s):
"Check if input string is an int"
try:
int(s)
return True
except ValueError:
return False
def checkFloat(s):
"Check if input string is a float"
try:
float(s)
return True
except ValueError:
return False
def makeNumeric(s):
"Convert string to int or float if numeric."
if checkInt(s):
return int(s)
elif checkFloat(s):
return float(s)
else:
return s
# Popen support
def pmonitor(popens, timeoutms=500, readline=True,
readmax=1024):
"""Monitor dict of hosts to popen objects
a line at a time
timeoutms: timeout for poll()
readline: return single line of output
yields: host, line/output (if any)
terminates: when all EOFs received"""
poller = poll()
fdToHost = {}
for host, popen in popens.iteritems():
fd = popen.stdout.fileno()
fdToHost[ fd ] = host
poller.register(fd, POLLIN)
if not readline:
# Use non-blocking reads
flags = fcntl(fd, F_GETFL)
fcntl(fd, F_SETFL, flags | O_NONBLOCK)
while popens:
fds = poller.poll(timeoutms)
if fds:
for fd, event in fds:
host = fdToHost[ fd ]
popen = popens[ host ]
if event & POLLIN:
if readline:
# Attempt to read a line of output
# This blocks until we receive a newline!
line = popen.stdout.readline()
else:
line = popen.stdout.read(readmax)
yield host, line
# Check for EOF
elif event & POLLHUP:
poller.unregister(fd)
del popens[ host ]
else:
yield None, ''
# Other stuff we use
def sysctlTestAndSet(name, limit):
"Helper function to set sysctl limits"
# convert non-directory names into directory names
if '/' not in name:
name = '/proc/sys/' + name.replace('.', '/')
# read limit
with open(name, 'r') as readFile:
oldLimit = readFile.readline()
if isinstance(limit, int):
# compare integer limits before overriding
if int(oldLimit) < limit:
with open(name, 'w') as writeFile:
writeFile.write("%d" % limit)
else:
# overwrite non-integer limits
with open(name, 'w') as writeFile:
writeFile.write(limit)
def rlimitTestAndSet(name, limit):
"Helper function to set rlimits"
soft, hard = getrlimit(name)
if soft < limit:
hardLimit = hard if limit < hard else limit
setrlimit(name, (limit, hardLimit))
def fixLimits():
"Fix ridiculously small resource limits."
debug("*** Setting resource limits\n")
try:
rlimitTestAndSet(RLIMIT_NPROC, 8192)
rlimitTestAndSet(RLIMIT_NOFILE, 16384)
# Increase open file limit
sysctlTestAndSet('fs.file-max', 10000)
# Increase network buffer space
sysctlTestAndSet('net.core.wmem_max', 16777216)
sysctlTestAndSet('net.core.rmem_max', 16777216)
sysctlTestAndSet('net.ipv4.tcp_rmem', '10240 87380 16777216')
sysctlTestAndSet('net.ipv4.tcp_wmem', '10240 87380 16777216')
sysctlTestAndSet('net.core.netdev_max_backlog', 5000)
# Increase arp cache size
sysctlTestAndSet('net.ipv4.neigh.default.gc_thresh1', 4096)
sysctlTestAndSet('net.ipv4.neigh.default.gc_thresh2', 8192)
sysctlTestAndSet('net.ipv4.neigh.default.gc_thresh3', 16384)
# Increase routing table size
sysctlTestAndSet('net.ipv4.route.max_size', 32768)
# Increase number of PTYs for nodes
sysctlTestAndSet('kernel.pty.max', 20000)
# pylint: disable=broad-except
except Exception:
warn("*** Error setting resource limits. "
"Mininet's performance may be affected.\n")
# pylint: enable=broad-except
def mountCgroups():
"Make sure cgroups file system is mounted"
mounts = quietRun('cat /proc/mounts')
cgdir = '/sys/fs/cgroup'
csdir = cgdir + '/cpuset'
if ('cgroup %s' % cgdir not in mounts and
'cgroups %s' % cgdir not in mounts):
raise Exception("cgroups not mounted on " + cgdir)
if 'cpuset %s' % csdir not in mounts:
errRun('mkdir -p ' + csdir)
errRun('mount -t cgroup -ocpuset cpuset ' + csdir)
def natural(text):
"To sort sanely/alphabetically: sorted( l, key=natural )"
def num(s):
"Convert text segment to int if necessary"
return int(s) if s.isdigit() else s
return [ num(s) for s in re.split(r'(\d+)', str(text)) ]
def naturalSeq(t):
"Natural sort key function for sequences"
return [ natural(x) for x in t ]
def numCores():
"Returns number of CPU cores based on /proc/cpuinfo"
if hasattr(numCores, 'ncores'):
return numCores.ncores
try:
numCores.ncores = int(quietRun('grep -c processor /proc/cpuinfo'))
except ValueError:
return 0
return numCores.ncores
def irange(start, end):
"""Inclusive range from start to end (vs. Python insanity.)
irange(1,5) -> 1, 2, 3, 4, 5"""
return range(start, end + 1)
def custom(cls, **params):
"Returns customized constructor for class cls."
# Note: we may wish to see if we can use functools.partial() here
# and in customConstructor
def customized(*args, **kwargs):
"Customized constructor"
kwargs = kwargs.copy()
kwargs.update(params)
return cls(*args, **kwargs)
customized.__name__ = 'custom(%s,%s)' % (cls, params)
return customized
def splitArgs(argstr):
"""Split argument string into usable python arguments
argstr: argument string with format fn,arg2,kw1=arg3...
returns: fn, args, kwargs"""
split = argstr.split(',')
fn = split[ 0 ]
params = split[ 1: ]
# Convert int and float args; removes the need for function
# to be flexible with input arg formats.
args = [ makeNumeric(s) for s in params if '=' not in s ]
kwargs = {}
for s in [ p for p in params if '=' in p ]:
key, val = s.split('=', 1)
kwargs[ key ] = makeNumeric(val)
return fn, args, kwargs
def customClass(classes, argStr):
"""Return customized class based on argStr
The args and key/val pairs in argStr will be automatically applied
when the generated class is later used.
"""
cname, args, kwargs = splitArgs(argStr)
cls = classes.get(cname, None)
if not cls:
raise Exception("error: %s is unknown - please specify one of %s"
% (cname, classes.keys()))
if not args and not kwargs:
return cls
return specialClass(cls, append=args, defaults=kwargs)
def specialClass(cls, prepend=None, append=None,
defaults=None, override=None):
"""Like functools.partial, but it returns a class
prepend: arguments to prepend to argument list
append: arguments to append to argument list
defaults: default values for keyword arguments
override: keyword arguments to override"""
if prepend is None:
prepend = []
if append is None:
append = []
if defaults is None:
defaults = {}
if override is None:
override = {}
class CustomClass(cls):
"Customized subclass with preset args/params"
def __init__(self, *args, **params):
newparams = defaults.copy()
newparams.update(params)
newparams.update(override)
cls.__init__(self, *(list(prepend) + list(args) +
list(append)), **newparams)
CustomClass.__name__ = '%s%s' % (cls.__name__, defaults)
return CustomClass
def buildTopo(topos, topoStr):
"""Create topology from string with format (object, arg1, arg2,...).
input topos is a dict of topo names to constructors, possibly w/args.
"""
topo, args, kwargs = splitArgs(topoStr)
if topo not in topos:
raise Exception('Invalid topo name %s' % topo)
return topos[ topo ](*args, **kwargs)
def ensureRoot():
"""Ensure that we are running as root.
Probably we should only sudo when needed as per Big Switch's patch.
"""
if os.getuid() != 0:
print "*** Mininet must run as root."
exit(1)
return
def waitListening(client=None, server='127.0.0.1', port=80, timeout=None):
"""Wait until server is listening on port.
returns True if server is listening"""
runCmd = (client.cmd if client else
partial(quietRun, shell=True))
if not runCmd('which telnet'):
raise Exception('Could not find telnet')
# pylint: disable=maybe-no-member
serverIP = server if isinstance(server, basestring) else server.IP()
cmd = ('echo A | telnet -e A %s %s' % (serverIP, port))
time = 0
result = runCmd(cmd)
while 'Connected' not in result:
if 'No route' in result:
rtable = runCmd('route')
error('no route to %s:\n%s' % (server, rtable))
return False
if timeout and time >= timeout:
error('could not connect to %s on port %d\n' % (server, port))
return False
debug('waiting for', server, 'to listen on port', port, '\n')
info('.')
sleep(.5)
time += .5
result = runCmd(cmd)
return True