How to use the scenario.dwr_handler function in scenario

def testScn(host, port, scenario):
    # run once in order to capture exchanged pdus
    f = sk.socket(sk.AF_INET, sk.SOCK_STREAM)
    f.connect((host, port))
    (exc_info, msgs) = dwr_handler(scenario, f, local_hostname, local_realm)
    if exc_info is not None:
        print >> sys.stderr, '[ERROR] The scenario raised %r' % exc_info
        sys.exit(1)
    f.close()

    return msgs

if exc_info is not None:
        logging.warning('scenario %s raised: %s' % (fuzz.description, exc_info))
      f.close()

  elif args.mode == 'server':
    srv = sk.socket(sk.AF_INET, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
    if args.local_addresses:
      addrs = [(a, int(args.local_port)) for a in args.local_addresses]
      ret = sctp.bindx(srv, addrs)
      assert(ret == 0)
    else:
      srv.bind(('0.0.0.0', args.local_port))
    srv.listen(64)

    (f,_) = srv.accept()
    (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm)
    if exc_info is not None:
      logging.warning('vanilla scenario raised: %s' % (exc_info))
      sys.exit(1)
    f.close()

    for (m, is_sent) in msgs:
      Directory.tag(m)

    fuzzs = analyze(msgs)
    logging.info('generated %d scenarios of fuzzing' % len(fuzzs))

    for fuzz in fuzzs:
      (f,_) = srv.accept()
      (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm, fuzz)
      if exc_info is not None:
        logging.warning('scenario %s raised: %s' % (fuzz.description, exc_info))

logging.basicConfig(format='%(asctime)s %(message)s', level=logging.WARNING)

  if args.mode == 'client':
    # run once in order to capture exchanged pdus
    f = sk.socket(sk.AF_INET, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
    if args.local_addresses:
      addrs = [(a, 0) for a in args.local_addresses]
      ret = sctp.bindx(f, addrs)
      assert(ret == 0)
    else:
      f.bind(('0.0.0.0', args.local_port))
    f.connect((host, port))

    (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm)
    if exc_info is not None:
      logging.warning('vanilla scenario raised: %s' % (exc_info))
      sys.exit(1)
    f.close()

    for (m, is_sent) in msgs:
      Directory.tag(m)

    fuzzs = analyze(msgs)
    logging.info('generated %d scenarios of fuzzing' % len(fuzzs))

    for fuzz in fuzzs:
      f = sk.socket(sk.AF_INET, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
      if args.local_addresses:
        addrs = [(a, 0) for a in args.local_addresses]
        ret = sctp.bindx(f, addrs)

startT = time.time()
        print("Scan started on %s..." % time.ctime())
        for (i, fuzz) in analyze(msgs, vendor, args.min, args.max):
            endT = time.time()
            m, s = divmod(endT-startT, 60)
            h, m = divmod(m, 60)
            elapsedT = (h,m,s)

            if i % 1000 == 0 and i> args.min:
                percent = ((i-args.min)*100.0)/((args.max - args.min)*1.0)
                print("%s - [INFO] %f%% : AVP %d to %d scanned (over %d) in %d:%d:%d..." % (time.ctime(), percent, i-1000, i, args.max, elapsedT[0], elapsedT[1], elapsedT[2]))

            try: 
                f = sk.socket(sk.AF_INET, sk.SOCK_STREAM)
                f.connect((host, port))
                (exc_info, msgs) = dwr_handler(scenario, f, local_hostname, local_realm, mutator=fuzz)
                f.close()
            except sk.error as serr:
                print >> sys.stderr, '%s - [ERROR] Connexion broken (%s) for AVP %d' % (time.ctime(), serr, i)
                try:
                    testScn(host, port, scenario)
                except sk.error as serr:
                    print >> sys.stderr, '%s - [ERROR] Connexion definitively broken (%s). I quit.' % (time.ctime(), serr)
                    sys.exit(-1)
                
                continue
            
            # Get the last message returned by fuzz_handler
            # Which is the server's response to the fuzzed message
            response = msgs[-1][0]
            if response.code != msgs[0][0].code:
                print('%s - [NOTI] Weird response (msg code %d) to AVP code %d.' % (time.ctime(), response.code, i))

(f,_) = srv.accept()
    (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm)
    if exc_info is not None:
      logging.warning('vanilla scenario raised: %s' % (exc_info))
      sys.exit(1)
    f.close()

    for (m, is_sent) in msgs:
      Directory.tag(m)

    fuzzs = analyze(msgs)
    logging.info('generated %d scenarios of fuzzing' % len(fuzzs))

    for fuzz in fuzzs:
      (f,_) = srv.accept()
      (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm, fuzz)
      if exc_info is not None:
        logging.warning('scenario %s raised: %s' % (fuzz.description, exc_info))
      f.close()

Directory.tag(m)

    fuzzs = analyze(msgs)
    logging.info('generated %d scenarios of fuzzing' % len(fuzzs))

    for fuzz in fuzzs:
      f = sk.socket(sk.AF_INET, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
      if args.local_addresses:
        addrs = [(a, 0) for a in args.local_addresses]
        ret = sctp.bindx(f, addrs)
        assert(ret == 0)
      else:
        f.bind(('0.0.0.0', args.local_port))
      f.connect((host, port))

      (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm, fuzz)
      if exc_info is not None:
        logging.warning('scenario %s raised: %s' % (fuzz.description, exc_info))
      f.close()

  elif args.mode == 'server':
    srv = sk.socket(sk.AF_INET, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
    if args.local_addresses:
      addrs = [(a, int(args.local_port)) for a in args.local_addresses]
      ret = sctp.bindx(srv, addrs)
      assert(ret == 0)
    else:
      srv.bind(('0.0.0.0', args.local_port))
    srv.listen(64)

    (f,_) = srv.accept()
    (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm)

# load scenario
  scenario = load_scenario(args.scenario, args.local_hostname, args.local_realm)

  if args.mode in ('client', 'clientloop'):
    while True:
      f = sk.socket(family, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
      if args.local_addresses:
        addrs = [(a, int(args.local_port)) for a in args.local_addresses]
        ret = sctp.bindx(f, addrs, family)
        assert(ret == 0)
      else:
        f.bind((ADDR_ANY, args.local_port))

      f.connect((target, port))

      (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm)
      if exc_info is not None:
        print('raised: %s' % (exc_info))
      f.close()

      if args.mode == 'client':
        break
  elif args.mode == 'server':
    srv = sk.socket(family, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
    if args.local_addresses:
      addrs = [(a, int(args.local_port)) for a in args.local_addresses]
      ret = sctp.bindx(srv, addrs, family)
      assert(ret == 0)
    else:
      srv.bind((ADDR_ANY, args.local_port))
    srv.listen(64)

if args.mode == 'client':
        break
  elif args.mode == 'server':
    srv = sk.socket(family, sk.SOCK_STREAM, sk.IPPROTO_SCTP)
    if args.local_addresses:
      addrs = [(a, int(args.local_port)) for a in args.local_addresses]
      ret = sctp.bindx(srv, addrs, family)
      assert(ret == 0)
    else:
      srv.bind((ADDR_ANY, args.local_port))
    srv.listen(64)

    while True:
      (f,_) = srv.accept()
      (exc_info, msgs) = dwr_handler(scenario, f, args.local_hostname, args.local_realm)
      if exc_info is not None:
        print('raised: %s' % (exc_info))
      f.close()