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mininet / mininet / node.py @ 89bf3103

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#!/usr/bin/env python
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'''Node objects for Mininet.'''
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from subprocess import Popen, PIPE, STDOUT
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import os, signal, sys, select
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flush = sys.stdout.flush
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from mininet.logging_mod import lg
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from mininet.util import quietRun
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class Node(object):
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    '''A virtual network node is simply a shell in a network namespace.
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       We communicate with it using pipes.'''
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    inToNode = {}
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    outToNode = {}
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    def __init__(self, name, inNamespace = True):
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        self.name = name
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        closeFds = False # speed vs. memory use
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        # xpg_echo is needed so we can echo our sentinel in sendCmd
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        cmd = ['/bin/bash', '-O', 'xpg_echo']
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        self.inNamespace = inNamespace
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        if self.inNamespace:
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            cmd = ['netns'] + cmd
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        self.shell = Popen(cmd, stdin = PIPE, stdout = PIPE, stderr = STDOUT,
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            close_fds = closeFds)
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        self.stdin = self.shell.stdin
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        self.stdout = self.shell.stdout
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        self.pollOut = select.poll()
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        self.pollOut.register(self.stdout)
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        # Maintain mapping between file descriptors and nodes
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        # This could be useful for monitoring multiple nodes
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        # using select.poll()
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        self.outToNode[self.stdout.fileno()] = self
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        self.inToNode[self.stdin.fileno()] = self
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        self.pid = self.shell.pid
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        self.intfCount = 0
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        self.intfs = [] # list of interface names, as strings
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        self.ips = {}
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        self.connection = {}
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        self.waiting = False
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        self.execed = False
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    def fdToNode(self, f):
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        '''Insert docstring.
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        @param f unknown
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        @return bool unknown
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        '''
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        node = self.outToNode.get(f)
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        return node or self.inToNode.get(f)
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    def cleanup(self):
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        '''Help python collect its garbage.'''
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        self.shell = None
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    # Subshell I/O, commands and control
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    def read(self, fileno_max):
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        '''Insert docstring.
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        @param fileno_max unknown
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        '''
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        return os.read(self.stdout.fileno(), fileno_max)
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    def write(self, data):
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        '''Write data to node.
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        @param data string
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        '''
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        os.write(self.stdin.fileno(), data)
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    def terminate(self):
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        '''Send kill signal to Node and cleanup after it.'''
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        os.kill(self.pid, signal.SIGKILL)
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        self.cleanup()
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    def stop(self):
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        '''Stop node.'''
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        self.terminate()
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    def waitReadable(self):
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        '''Poll on node.'''
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        self.pollOut.poll()
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    def sendCmd(self, cmd):
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        '''Send a command, followed by a command to echo a sentinel,
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           and return without waiting for the command to complete.'''
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        assert not self.waiting
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        if cmd[-1] == '&':
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            separator = '&'
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            cmd = cmd[:-1]
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        else:
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            separator = ';'
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        if isinstance(cmd, list):
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            cmd = ' '.join(cmd)
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        self.write(cmd + separator + ' echo -n "\\0177" \n')
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        self.waiting = True
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    def monitor(self):
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        '''Monitor the output of a command, returning (done, data).'''
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        assert self.waiting
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        self.waitReadable()
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        data = self.read(1024)
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        if len(data) > 0 and data[-1] == chr(0177):
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            self.waiting = False
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            return True, data[:-1]
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        else:
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            return False, data
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    def sendInt(self):
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        '''Send ^C, hopefully interrupting a running subprocess.'''
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        self.write(chr(3))
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    def waitOutput(self):
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        '''Wait for a command to complete.
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        Completion is signaled by a sentinel character, ASCII(127) appearing in
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        the output stream.  Wait for the sentinel and return the output,
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        including trailing newline.
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        '''
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        assert self.waiting
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        output = ''
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        while True:
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            self.waitReadable()
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            data = self.read(1024)
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            if len(data) > 0  and data[-1] == chr(0177):
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                output += data[:-1]
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                break
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            else: output += data
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        self.waiting = False
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        return output
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    def cmd(self, cmd):
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        '''Send a command, wait for output, and return it.
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        @param cmd string
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        '''
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        self.sendCmd(cmd)
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        return self.waitOutput()
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    def cmdPrint(self, cmd):
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        '''Call cmd and printing its output
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        @param cmd string
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        '''
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        #lg.info('*** %s : %s', self.name, cmd)
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        result = self.cmd(cmd)
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        #lg.info('%s\n', result)
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        return result
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    # Interface management, configuration, and routing
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    def intfName(self, n):
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        '''Construct a canonical interface name node-intf for interface N.'''
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        return self.name + '-eth' + repr(n)
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    def newIntf(self):
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        '''Reserve and return a new interface name.'''
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        intfName = self.intfName(self.intfCount)
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        self.intfCount += 1
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        self.intfs += [intfName]
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        return intfName
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    def setIP(self, intf, ip, bits):
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        '''Set the IP address for an interface.
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        @param intf string, interface name
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        @param ip IP address as integer
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        @param bits
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        '''
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        result = self.cmd(['ifconfig', intf, ip + bits, 'up'])
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        self.ips[intf] = ip
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        return result
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    def setHostRoute(self, ip, intf):
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        '''Add route to host.
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        @param ip IP address as dotted decimal
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        @param intf string, interface name
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        '''
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        return self.cmd('route add -host ' + ip + ' dev ' + intf)
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    def setDefaultRoute(self, intf):
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        '''Set the default route to go through intf.
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        @param intf string, interface name
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        '''
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        self.cmd('ip route flush')
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        return self.cmd('route add default ' + intf)
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    def IP(self):
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        '''Return IP address of first interface'''
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        if len(self.intfs) > 0:
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            return self.ips.get(self.intfs[ 0 ], None)
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    def intfIsUp(self):
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        '''Check if one of our interfaces is up.'''
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        return 'UP' in self.cmd('ifconfig ' + self.intfs[0])
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    # Other methods
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    def __str__(self):
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        result = self.name + ':'
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        if self.IP():
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            result += ' IP=' + self.IP()
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        result += ' intfs=' + ','.join(self.intfs)
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        result += ' waiting=' + repr(self.waiting)
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        return result
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class Host(Node):
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    '''A host is simply a Node.'''
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    pass
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class Controller(Node):
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    '''A Controller is a Node that is running (or has execed) an
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      OpenFlow controller.'''
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    def __init__(self, name, kernel=True, controller='controller',
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                 cargs='-v ptcp:', cdir=None):
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        self.controller = controller
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        self.cargs = cargs
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        self.cdir = cdir
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        Node.__init__(self, name, inNamespace=(not kernel))
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    def start(self):
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        '''Start <controller> <args> on controller.
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        Log to /tmp/cN.log
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        '''
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        cout = '/tmp/' + self.name + '.log'
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        if self.cdir is not None:
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            self.cmdPrint('cd ' + self.cdir)
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        self.cmdPrint(self.controller + ' ' + self.cargs +
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            ' 1> ' + cout + ' 2> ' + cout + ' &')
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        self.execed = False # XXX Until I fix it
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    def stop(self):
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        '''Stop controller.'''
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        self.cmd('kill %' + self.controller)
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        self.terminate()
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class Switch(Node):
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    '''A Switch is a Node that is running (or has execed)
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       an OpenFlow switch.'''
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    def __init__(self, name, datapath = None):
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        '''Init.
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        @param name
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        @param datapath string, datapath name
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        '''
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        self.dp = datapath
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        Node.__init__(self, name, inNamespace = (datapath == None))
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    def _startUserDatapath(self, controller):
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        '''Start OpenFlow reference user datapath.
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        Log to /tmp/sN-{ofd,ofp}.log.
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        @param controller Controller object.
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        '''
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        ofdlog = '/tmp/' + self.name + '-ofd.log'
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        ofplog = '/tmp/' + self.name + '-ofp.log'
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        self.cmd('ifconfig lo up')
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        intfs = self.intfs[1:] # 0 is mgmt interface
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        self.cmdPrint('ofdatapath -i ' + ','.join(intfs) +
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                      ' ptcp: 1> ' + ofdlog + ' 2> ' + ofdlog + ' &')
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        self.cmdPrint('ofprotocol tcp:' + controller.IP() +
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                      ' tcp:localhost --fail=closed 1> ' + ofplog + ' 2>' +
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                      ofplog + ' &')
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    def _stopUserDatapath(self):
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        '''Stop OpenFlow reference user datapath.'''
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        self.cmd('kill %ofdatapath')
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        self.cmd('kill %ofprotocol')
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    def _startKernelDatapath(self):
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        '''Start up reference kernel datapath.'''
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        ofplog = '/tmp/' + self.name + '-ofp.log'
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        quietRun('ifconfig lo up')
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        # Delete local datapath if it exists;
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        # then create a new one monitoring the given interfaces
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        quietRun('dpctl deldp ' + self.dp)
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        self.cmdPrint('dpctl adddp ' + self.dp)
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        self.cmdPrint('dpctl addif ' + self.dp + ' ' + ' '.join(self.intfs))
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        # Run protocol daemon
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        self.cmdPrint('ofprotocol' +
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                      ' ' + self.dp + ' tcp:127.0.0.1 ' +
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                      ' --fail=closed 1> ' + ofplog + ' 2>' + ofplog + ' &')
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        self.execed = False # XXX until I fix it
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    def _stopKernelDatapath(self):
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        '''Terminate reference kernel datapath.'''
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        quietRun('dpctl deldp ' + self.dp)
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        # In theory the interfaces should go away after we shut down.
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        # However, this takes time, so we're better off to remove them
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        # explicitly so that we won't get errors if we run before they
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        # have been removed by the kernel. Unfortunately this is very slow.
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        self.cmd('kill %ofprotocol')
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        for intf in self.intfs:
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            quietRun('ip link del ' + intf)
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            lg.info('.')
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    def start(self, controller):
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        '''Start datapath.
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        @param controller Controller object
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        '''
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        if self.dp is None:
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            self._startUserDatapath(controller)
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        else:
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            self._startKernelDatapath()
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    def stop(self):
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        '''Stop datapath.'''
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        if self.dp is None:
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            self._stopUserDatapath()
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        else:
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            self._stopKernelDatapath()
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    def sendCmd(self, cmd):
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        '''Send command to Node.
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        @param cmd string
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        '''
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        if not self.execed:
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            return Node.sendCmd(self, cmd)
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        else:
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            lg.error('*** Error: %s has execed and cannot accept commands' %
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                     self.name)
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    def monitor(self):
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        '''Monitor node.'''
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        if not self.execed:
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            return Node.monitor(self)
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        else:
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            return True, ''