NePA TesT: Community Network Emulator

"""

link.py: interface and link abstractions for mininet

It seems useful to bundle functionality for interfaces into a single

class.

Also it seems useful to enable the possibility of multiple flavors of

links, including:

- simple veth pairs

- tunneled links

- patchable links (which can be disconnected and reconnected via a patchbay)

- link simulators (e.g. wireless)

Basic division of labor:

  Nodes: know how to execute commands

  Intfs: know how to configure themselves

  Links: know how to connect nodes together

Intf: basic interface object that can configure itself

TCIntf: interface with bandwidth limiting and delay via tc

Link: basic link class for creating veth pairs

"""

from mininet.log import info, error, debug

from mininet.util import makeIntfPair

from time import sleep

import re

class Intf( object ):

    "Basic interface object that can configure itself."

    def __init__( self, name, node=None, port=None, link=None, **params ):

        """name: interface name (e.g. h1-eth0)

           node: owning node (where this intf most likely lives)

           link: parent link if we're part of a link

           other arguments are passed to config()"""

        self.node = node

        self.name = name

        self.link = link

        self.mac, self.ip, self.prefixLen = None, None, None

        # Add to node (and move ourselves if necessary )

        node.addIntf( self, port=port )

        # Save params for future reference

        self.params = params

        self.config( **params )

    def cmd( self, *args, **kwargs ):

        "Run a command in our owning node"

        return self.node.cmd( *args, **kwargs )

    def ifconfig( self, *args ):

        "Configure ourselves using ifconfig"

        return self.cmd( 'ifconfig', self.name, *args )

    def setIP( self, ipstr, prefixLen=None ):

        """Set our IP address"""

        # This is a sign that we should perhaps rethink our prefix

        # mechanism and/or the way we specify IP addresses

        if '/' in ipstr:

            self.ip, self.prefixLen = ipstr.split( '/' )

            return self.ifconfig( ipstr, 'up' )

        else:

            self.ip, self.prefixLen = ipstr, prefixLen

            return self.ifconfig( '%s/%s' % ( ipstr, prefixLen ) )

    def setMAC( self, macstr ):

        """Set the MAC address for an interface.

           macstr: MAC address as string"""

        self.mac = macstr

        return ( self.ifconfig( 'down' ) +

                 self.ifconfig( 'hw', 'ether', macstr ) +

                 self.ifconfig( 'up' ) )

    _ipMatchRegex = re.compile( r'\d+\.\d+\.\d+\.\d+' )

    _macMatchRegex = re.compile( r'..:..:..:..:..:..' )

    def updateIP( self ):

        "Return updated IP address based on ifconfig"

        ifconfig = self.ifconfig()

        ips = self._ipMatchRegex.findall( ifconfig )

        self.ip = ips[ 0 ] if ips else None

        return self.ip

    def updateMAC( self ):

        "Return updated MAC address based on ifconfig"

        ifconfig = self.ifconfig()

        macs = self._macMatchRegex.findall( ifconfig )

        self.mac = macs[ 0 ] if macs else None

        return self.mac

    def IP( self ):

        "Return IP address"

        return self.ip

    def MAC( self ):

        "Return MAC address"

        return self.mac

    def isUp( self, setUp=False ):

        "Return whether interface is up"

        if setUp:

            self.ifconfig( 'up' )

        return "UP" in self.ifconfig()

    def rename( self, newname ):

        "Rename interface"

        self.ifconfig( 'down' )

        result = self.cmd( 'ip link set', self.name, 'name', newname )

        self.name = newname

        self.ifconfig( 'up' )

        return result

    # The reason why we configure things in this way is so

    # That the parameters can be listed and documented in

    # the config method.

    # Dealing with subclasses and superclasses is slightly

    # annoying, but at least the information is there!

    def setParam( self, results, method, **param ):

        """Internal method: configure a *single* parameter

           results: dict of results to update

           method: config method name

           param: arg=value (ignore if value=None)

           value may also be list or dict"""

        name, value = param.items()[ 0 ]

        f = getattr( self, method, None )

        if not f or value is None:

            return

        if type( value ) is list:

            result = f( *value )

        elif type( value ) is dict:

            result = f( **value )

        else:

            result = f( value )

        results[ name ] = result

        return result

    def config( self, mac=None, ip=None, ifconfig=None,

                up=True, **_params ):

        """Configure Node according to (optional) parameters:

           mac: MAC address

           ip: IP address

           ifconfig: arbitrary interface configuration

           Subclasses should override this method and call

           the parent class's config(**params)"""

        # If we were overriding this method, we would call

        # the superclass config method here as follows:

        # r = Parent.config( **params )

        r = {}

        self.setParam( r, 'setMAC', mac=mac )

        self.setParam( r, 'setIP', ip=ip )

        self.setParam( r, 'isUp', up=up )

        self.setParam( r, 'ifconfig', ifconfig=ifconfig )

        self.updateIP()

        self.updateMAC()

        return r

    def delete( self ):

        "Delete interface"

        self.cmd( 'ip link del ' + self.name )

        # Does it help to sleep to let things run?

        sleep( 0.001 )

    def __repr__( self ):

        return '<%s %s>' % ( self.__class__.__name__, self.name )

    def __str__( self ):

        return self.name

class TCIntf( Intf ):

    """Interface customized by tc (traffic control) utility

       Allows specification of bandwidth limits (various methods)

       as well as delay, loss and max queue length"""

    def bwCmds( self, bw=None, speedup=0, use_hfsc=False, use_tbf=False,

                enable_ecn=False, enable_red=False ):

        "Return tc commands to set bandwidth"

        cmds, parent = [], ' root '

        if bw and ( bw < 0 or bw > 1000 ):

            error( 'Bandwidth', bw, 'is outside range 0..1000 Mbps\n' )

        elif bw is not None:

            # BL: this seems a bit brittle...

            if ( speedup > 0 and

                 self.node.name[0:1] == 's' ):

                bw = speedup

            burst = bw * 1e6 / 8 * .001

            # This may not be correct - we should look more closely

            # at the semantics of burst (and cburst) to make sure we

            # are specifying the correct sizes. For now I have used

            # the same settings we had in the mininet-hifi code.

            if use_hfsc:

                cmds = [ '%s qdisc add dev %s root handle 1:0 hfsc default 1',

                          '%s class add dev %s parent 1:0 classid 1:1 hfsc sc '

                          + 'rate %fMbit ul rate %fMbit' % ( bw, bw ) ]

            elif use_tbf:

                latency_us = 10 * 1500 * 8 / bw

                cmds = ['%s qdisc add dev %s root handle 1: tbf ' +

                        'rate %fMbit burst 15000 latency %fus' %

                         ( bw, latency_us ) ]

            else:

                cmds = [ '%s qdisc add dev %s root handle 1:0 htb default 1',

                         '%s class add dev %s parent 1:0 classid 1:1 htb ' +

                         'rate %fMbit burst 15k' % bw ]

            parent = ' parent 1:1 '

            # ECN or RED

            if enable_ecn:

                cmds = [ '%s qdisc add dev %s' + parent +

                          'handle 10: red limit 1000000 ' +

                          'min 20000 max 25000 avpkt 1000 ' +

                          'burst 20 ' +

                          'bandwidth %fmbit probability 1 ecn' % bw ]

                parent = ' parent 10: '

            elif enable_red:

                cmds = [ '%s qdisc add dev %s' + parent +

                          'handle 10: red limit 1000000 ' +

                          'min 20000 max 25000 avpkt 1000 ' +

                          'burst 20 ' +

                          'bandwidth %fmbit probability 1' % bw ]

                parent = ' parent 10: '

        return cmds, parent

    @staticmethod

    def delayCmds( parent, delay=None, loss=None,

                   max_queue_size=None ):

        "Internal method: return tc commands for delay and loss"

        cmds = []

        if delay and delay < 0:

            error( 'Negative delay', delay, '\n' )

        elif loss and ( loss < 0 or loss > 100 ):

            error( 'Bad loss percentage', loss, '%%\n' )

        else:

            # Delay/loss/max queue size

            netemargs = '%s%s%s' % (

                'delay %s ' % delay if delay is not None else '',

                'loss %d ' % loss if loss is not None else '',

                'limit %d' % max_queue_size if max_queue_size is not None

                 else '' )

            if netemargs:

                cmds = [ '%s qdisc add dev %s ' + parent + ' netem ' +

                          netemargs ]

        return cmds

    def tc( self, cmd, tc='tc' ):

        "Execute tc command for our interface"

        c = cmd % (tc, self)  # Add in tc command and our name

        debug(" *** executing command: %s\n" % c)

        return self.cmd( c )

    def config( self, bw=None, delay=None, loss=None, disable_gro=True,

                speedup=0, use_hfsc=False, use_tbf=False, enable_ecn=False,

                enable_red=False, max_queue_size=None, **params ):

        "Configure the port and set its properties."

        result = Intf.config( self, **params)

        # Disable GRO

        if disable_gro:

            self.cmd( 'ethtool -K %s gro off' % self )

        # Optimization: return if nothing else to configure

        # Question: what happens if we want to reset things?

        if ( bw is None and not delay and not loss

             and max_queue_size is None ):

            return

        # Clear existing configuration

        cmds = [ '%s qdisc del dev %s root' ]

        # Bandwidth limits via various methods

        bwcmds, parent = self.bwCmds( bw=bw, speedup=speedup,

                                 use_hfsc=use_hfsc, use_tbf=use_tbf,

                                 enable_ecn=enable_ecn,

                                 enable_red=enable_red )

        cmds += bwcmds

        # Delay/loss/max_queue_size using netem

        cmds += self.delayCmds( delay=delay, loss=loss,

                                 max_queue_size=max_queue_size,

                                 parent=parent )

        # Ugly but functional: display configuration info

        stuff = ( ( [ '%.2fMbit' % bw ] if bw is not None else [] ) +

                  ( [ '%s delay' % delay ] if delay is not None else [] ) +

                  ( ['%d%% loss' % loss ] if loss is not None else [] ) +

                  ( [ 'ECN' ] if enable_ecn  else [ 'RED' ]

                    if enable_red else [] ) )

        info( '(' + ' '.join( stuff ) + ') ' )

        # Execute all the commands in our node

        debug("at map stage w/cmds: %s\n" % cmds)

        tcoutputs = [ self.tc(cmd) for cmd in cmds ]

        debug( "cmds:", cmds, '\n' )

        debug( "outputs:", tcoutputs, '\n' )

        result[ 'tcoutputs'] = tcoutputs

        return result

class Link( object ):

    """A basic link is just a veth pair.

       Other types of links could be tunnels, link emulators, etc.."""

    def __init__( self, node1, node2, port1=None, port2=None,

                  intfName1=None, intfName2=None,

                  intf=Intf, cls1=None, cls2=None, params1=None,

                  params2=None ):

        """Create veth link to another node, making two new interfaces.

           node1: first node

           node2: second node

           port1: node1 port number (optional)

           port2: node2 port number (optional)

           intf: default interface class/constructor

           cls1, cls2: optional interface-specific constructors

           intfName1: node1 interface name (optional)

           intfName2: node2  interface name (optional)

           params1: parameters for interface 1

           params2: parameters for interface 2"""

        # This is a bit awkward; it seems that having everything in

        # params would be more orthogonal, but being able to specify

        # in-line arguments is more convenient!

        if port1 is None:

            port1 = node1.newPort()

        if port2 is None:

            port2 = node2.newPort()

        if not intfName1:

            intfName1 = self.intfName( node1, port1 )

        if not intfName2:

            intfName2 = self.intfName( node2, port2 )

        self.makeIntfPair( intfName1, intfName2 )

        if not cls1:

            cls1 = intf

        if not cls2:

            cls2 = intf

        if not params1:

            params1 = {}

        if not params2:

            params2 = {}

        intf1 = cls1( name=intfName1, node=node1, port=port1,

                      link=self, **params1  )

        intf2 = cls2( name=intfName2, node=node2, port=port2,

                      link=self, **params2 )

        # All we are is dust in the wind, and our two interfaces

        self.intf1, self.intf2 = intf1, intf2

    @classmethod

    def intfName( cls, node, n ):

        "Construct a canonical interface name node-ethN for interface n."

        return node.name + '-eth' + repr( n )

    @classmethod

    def makeIntfPair( cls, intf1, intf2 ):

        """Create pair of interfaces

           intf1: name of interface 1

           intf2: name of interface 2

           (override this class method [and possibly delete()]

           to change link type)"""

        makeIntfPair( intf1, intf2  )

    def delete( self ):

        "Delete this link"

        self.intf1.delete()

        self.intf2.delete()

    def __str__( self ):

        return '%s<->%s' % ( self.intf1, self.intf2 )

class TCLink( Link ):

    "Link with symmetric TC interfaces configured via opts"

    def __init__( self, node1, node2, port1=None, port2=None,

                  intfName1=None, intfName2=None, **params ):

        Link.__init__( self, node1, node2, port1=port1, port2=port2,

                       intfName1=intfName1, intfName2=intfName2,

                       cls1=TCIntf,

                       cls2=TCIntf,

                       params1=params,

                       params2=params)