基类

即 mininet.node.Node，
表示一个基本的虚拟网络节点，是所有的网络节点的父类。

实现上其实就是在网络名字空间中的一个shell进程，可以通过各种管道进行通信。该类是模块中其他类的根本，其它类都是直接或间接继承。

节点包括名称、是否在网络名字空间、接口、端口等可能的属性。

init

  1.    params: Node parameters (see config() for details)"""
  3.         # Make sure class actually works
  4.         self.checkSetup()
  6.         self.name = name
  7.         self.inNamespace = inNamespace
  9.         # Stash configuration parameters for future reference
  10.         self.params = params
  12.         self.intfs = {}  # dict of port numbers to interfaces
  13.         self.ports = {}  # dict of interfaces to port numbers
  14.                          # replace with Port objects, eventually ?
  15.         self.nameToIntf = {}  # dict of interface names to Intfs
  17.         # Make pylint happy
  18.         ( self.shell, self.execed, self.pid, self.stdin, self.stdout,
  19.             self.lastPid, self.lastCmd, self.pollOut ) = (
  20.                 None, None, None, None, None, None, None, None )
  21.         self.waiting = False
  22.         self.readbuf = ''
  24.         # Start command interpreter shell
  25.         self.startShell()

初始化函数主要进行参数的初始化，之后通过调用 startShell() 启动一个 shell进程（该进程默认关闭描述符，并从 tty 上分离开来），等待接受传入的命令。句柄被发送给 self.shell 上。

addIntf

  1. def addIntf( self, intf, port=None ):
  2.         """Add an interface.
  3.            intf: interface
  4.            port: port number (optional, typically OpenFlow port number)"""
  5.         if port is None:
  6.             port = self.newPort()
  7.         self.intfs[ port ] = intf
  8.         self.ports[ intf ] = port
  9.         self.nameToIntf[ intf.name ] = intf
  10.         debug( '\n' )
  11.         debug( 'added intf %s:%d to node %s\n' % ( intf, port, self.name ) )
  12.         if self.inNamespace:
  13.             debug( 'moving', intf, 'into namespace for', self.name, '\n' )
  14.             moveIntf( intf.name, self )

添加一个接口（比如 <Intf h1-eth0> ）到节点上，如果给定了 port（比如 0 ），则建立端口到接口的映射关系。这个映射关系通过 self.intfs 和 self.ports 两个字典来分别维护。

cmd

该函数能在节点所在的进程shell上执行输入的命令。

  1. def cmd( self, *args, **kwargs ):
  2.         """Send a command, wait for output, and return it.
  3.            cmd: string"""
  4.         verbose = kwargs.get( 'verbose', False )
  5.         log = info if verbose else debug
  6.         log( '*** %s : %s\n' % ( self.name, args ) )
  7.         self.sendCmd( *args, **kwargs )
  8.         return self.waitOutput( verbose )

config

配置 MAC，IP 或 default Route 信息。

  1. def config( self, mac=None, ip=None,
  2.                 defaultRoute=None, lo='up', **_params ):
  3.         """Configure Node according to (optional) parameters:
  4.            mac: MAC address for default interface
  5.            ip: IP address for default interface
  6.            ifconfig: arbitrary interface configuration
  7.            Subclasses should override this method and call
  8.            the parent class's config(**params)"""
  9.         # If we were overriding this method, we would call
  10.         # the superclass config method here as follows:
  11.         # r = Parent.config( **_params )
  12.         r = {}
  13.         self.setParam( r, 'setMAC', mac=mac )
  14.         self.setParam( r, 'setIP', ip=ip )
  15.         self.setParam( r, 'setDefaultRoute', defaultRoute=defaultRoute )
  16.         # This should be examined
  17.         self.cmd( 'ifconfig lo ' + lo )
  18.         return r

connectionsTo

返回所有从自身连接到给定节点的接口，即 [ intf1, intf2… ]。

  1. def connectionsTo( self, node):
  2.         "Return [ intf1, intf2... ] for all intfs that connect self to node."
  3.         # We could optimize this if it is important
  4.         connections = []
  5.         for intf in self.intfList():
  6.             link = intf.link
  7.             if link:
  8.                 node1, node2 = link.intf1.node, link.intf2.node
  9.                 if node1 == self and node2 == node:
  10.                     connections += [ ( intf, link.intf2 ) ]
  11.                 elif node1 == node and node2 == self:
  12.                     connections += [ ( intf, link.intf1 ) ]
  13.         return connections