"Utility functions for Mininet."

from mininet.log import output, info, error, warn

from time import sleep

from resource import 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

# 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-msg=E1103

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

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"""

# Allow passing in a list or a string

if len( cmd ) == 1:

cmd = cmd[ 0 ]

if isinstance( cmd, str ):

cmd = cmd.split( ' ' )

cmd = [ str( arg ) for arg in cmd ]

# 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' )

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 ]

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

returncode = popen.wait()

return out, err, returncode

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-msg=E1103

# pylint: disable-msg=E1101

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

# pylint: enable-msg=E1101

# 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 ):

"""Make a veth pair connecting intf1 and intf2.

intf1: string, interface

intf2: string, interface

returns: success boolean"""

# Delete any old interfaces with the same names

quietRun( 'ip link del ' + intf1 )

quietRun( 'ip link del ' + intf2 )

# Create new pair

cmd = 'ip link add name ' + intf1 + ' type veth peer name ' + intf2

return quietRun( cmd )

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, srcNode=None, printError=False ):

"""Move interface to node, without retrying.

intf: string, interface

dstNode: destination Node

srcNode: source Node or None (default) for root ns

printError: if true, print error"""

intf = str( intf )

cmd = 'ip link set %s netns %s' % ( intf, dstNode.pid )

if srcNode:

srcNode.cmd( cmd )

else:

quietRun( cmd )

links = dstNode.cmd( 'ip link show' )

if not ( ' %s:' % intf ) in links:

if printError:

error( '*** Error: moveIntf: ' + intf +

' not successfully moved to ' + dstNode.name + '\n' )

return False

return True

def moveIntf( intf, dstNode, srcNode=None, printError=False,

retries=3, delaySecs=0.001 ):

"""Move interface to node, retrying on failure.

intf: string, interface

dstNode: destination Node

srcNode: source Node or None (default) for root ns

printError: if true, print error"""

retry( retries, delaySecs, moveIntfNoRetry, intf, dstNode,

srcNode=srcNode, 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 )

# 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

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( '.' ) ]

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 )

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 fixLimits():

"Fix ridiculously small resource limits."

setrlimit( RLIMIT_NPROC, ( 8192, 8192 ) )

setrlimit( RLIMIT_NOFILE, ( 16384, 16384 ) )

def mountCgroups():

"Make sure cgroups file system is mounted"

mounts = quietRun( 'mount' )

cgdir = '/sys/fs/cgroup'

csdir = cgdir + '/cpuset'

if ('cgroup on %s' % cgdir not in mounts and

'cgroups on %s' % cgdir not in mounts):

raise Exception( "cgroups not mounted on " + cgdir )

if 'cpuset on %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+)', 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 customConstructor( constructors, argStr ):

"""Return custom constructor based on argStr

The args and key/val pairs in argsStr will be automatically applied

when the generated constructor is later used.

"""

cname, newargs, kwargs = splitArgs( argStr )

constructor = constructors.get( cname, None )

if not constructor:

raise Exception( "error: %s is unknown - please specify one of %s" %

( cname, constructors.keys() ) )

def customized( name, *args, **params ):

"Customized constructor, useful for Node, Link, and other classes"

params = params.copy()

params.update( kwargs )

if not newargs:

return constructor( name, *args, **params )

if args:

warn( 'warning: %s replacing %s with %s\n' % (

constructor, args, newargs ) )

return constructor( name, *newargs, **params )

customized.__name__ = 'customConstructor(%s)' % argStr

return customized

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