gistfile1.py

class SyscallThread(Thread):
    def __init__(self, commandline):
        Thread.__init__(self)        
        self.cursor = 0
        self.lines = {self.cursor:[]}
        self.keep_running=False
        self.commandline=commandline
        
    def run(self): 
        print 'starting thread:', self        
        self.keep_running=True
        self.process = subprocess.Popen(self.commandline, 
            stdin=subprocess.PIPE, stdout=subprocess.PIPE, shell=True)
        self.outputfile = self.process.stdout
        while self.keep_running:
            for line in self.outputfile:
                self.lines[self.cursor].append(line)
                
        self.process.kill()
        
    def new_lines(self):
        newlines = self.lines[self.cursor]
        print '%d new lines' % len(newlines)        
        del self.lines[self.cursor]
        self.cursor += 1
        self.lines[self.cursor]=[]
        return (line for line in newlines)
        
    def stop(self):
        self.keep_running=False
        print 'stopping thread:', self
        
        
class TCPDumper(SyscallThread):
    def __init__(self, commandline):
        SyscallThread.__init__(self, commandline)
        
class TCPDumpHandler(tornado.web.RequestHandler):
    dumper = None
    stopping = None
    
    def post(self):        
        cls = TCPDumpHandler        

        # start the thread for first time
        if not self.get_argument('stop', None):
            if cls.dumper is None:
                iface = self.get_argument('iface', 'any')
                verbose = self.get_argument('verbose', None) and ' -vvvXX ' or ''
                cls.dumper = TCPDumper('tcpdump %s -nli %s "not port 5799"' % (verbose, iface))
                cls.dumper.start()            
            
            self.write(''.join(map(escape, cls.dumper.new_lines())))
            self.flush()

        # stop the thread
        elif cls.dumper:
            cls.dumper.stop()
            cls.dumper = None