#!/usr/bin/python

"""
Simple example of Mobility with Mininet
(aka enough rope to hang yourself.)

We move a host from s1 to s2, s2 to s3, and then back to s1.

Gotchas:

The reference controller doesn't support mobility, so we need to
manually flush the switch flow tables!

Good luck!

to-do:

- think about wifi/hub behavior
- think about clearing last hop - why doesn't that work?
"""

from mininet.net import Mininet
from mininet.node import OVSSwitch
from mininet.topo import LinearTopo
from mininet.log import output, warn

from random import randint


class MobilitySwitch( OVSSwitch ):
    "Switch that can reattach and rename interfaces"

    def delIntf( self, intf ):
        "Remove (and detach) an interface"
        port = self.ports[ intf ]
        del self.ports[ intf ]
        del self.intfs[ port ]
        del self.nameToIntf[ intf.name ]

    def addIntf( self, intf, rename=False, **kwargs ):
        "Add (and reparent) an interface"
        OVSSwitch.addIntf( self, intf, **kwargs )
        intf.node = self
        if rename:
            self.renameIntf( intf )

    def attach( self, intf ):
        "Attach an interface and set its port"
        port = self.ports[ intf ]
        if port:
            if self.isOldOVS():
                self.cmd( 'ovs-vsctl add-port', self, intf )
            else:
                self.cmd( 'ovs-vsctl add-port', self, intf,
                          '-- set Interface', intf,
                          'ofport_request=%s' % port )
            self.validatePort( intf )

    def validatePort( self, intf ):
        "Validate intf's OF port number"
        ofport = int( self.cmd( 'ovs-vsctl get Interface', intf,
                                'ofport' ) )
        if ofport != self.ports[ intf ]:
            warn( 'WARNING: ofport for', intf, 'is actually', ofport,
                  '\n' )

    def renameIntf( self, intf, newname='' ):
        "Rename an interface (to its canonical name)"
        intf.ifconfig( 'down' )
        if not newname:
            newname = '%s-eth%d' % ( self.name, self.ports[ intf ] )
        intf.cmd( 'ip link set', intf, 'name', newname )
        del self.nameToIntf[ intf.name ]
        intf.name = newname
        self.nameToIntf[ intf.name ] = intf
        intf.ifconfig( 'up' )

    def moveIntf( self, intf, switch, port=None, rename=True ):
        "Move one of our interfaces to another switch"
        self.detach( intf )
        self.delIntf( intf )
        switch.addIntf( intf, port=port, rename=rename )
        switch.attach( intf )


def printConnections( switches ):
    "Compactly print connected nodes to each switch"
    for sw in switches:
        output( '%s: ' % sw )
        for intf in sw.intfList():
            link = intf.link
            if link:
                intf1, intf2 = link.intf1, link.intf2
                remote = intf1 if intf1.node != sw else intf2
                output( '%s(%s) ' % ( remote.node, sw.ports[ intf ] ) )
        output( '\n' )


def moveHost( host, oldSwitch, newSwitch, newPort=None ):
    "Move a host from old switch to new switch"
    hintf, sintf = host.connectionsTo( oldSwitch )[ 0 ]
    oldSwitch.moveIntf( sintf, newSwitch, port=newPort )
    return hintf, sintf


def mobilityTest():
    "A simple test of mobility"
    print '* Simple mobility test'
    net = Mininet( topo=LinearTopo( 3 ), switch=MobilitySwitch )
    print '* Starting network:'
    net.start()
    printConnections( net.switches )
    print '* Testing network'
    net.pingAll()
    print '* Identifying switch interface for h1'
    h1, old = net.get( 'h1', 's1' )
    for s in 2, 3, 1:
        new = net[ 's%d' % s ]
        port = randint( 10, 20 )
        print '* Moving', h1, 'from', old, 'to', new, 'port', port
        hintf, sintf = moveHost( h1, old, new, newPort=port )
        print '*', hintf, 'is now connected to', sintf
        print '* Clearing out old flows'
        for sw in net.switches:
            sw.dpctl( 'del-flows' )
        print '* New network:'
        printConnections( net.switches )
        print '* Testing connectivity:'
        net.pingAll()
        old = new
    net.stop()

if __name__ == '__main__':
    mobilityTest()