add comments

    ms=int(datetime.datetime.now().microsecond/1000)

    ms='%03d'%ms

    print ('['+time.strftime('%Y-%m-%d %H:%M:%S',time.localtime(time.time()))+'.'+ms+'] '+s)     

    #May cause errors when string s contains unicode characters

def newConfig():

#Set up new config using default settings

    username=input('Username: ')

    passwd=input('Password: ')

    f=open('config.json','w')

        try:

            config=json.loads(f.readline())

            config and config['interval_retry_login'] and config['interval_check_status'] and config['username'] and config['password'] and config['interval_retry_connection'] and config['testUrl']

            #Check if the parameters all exist

        except KeyError as err:

            printWithTimeStamp('Parameter '+str(err)+' not found.')

            printWithTimeStamp('Configuration file is broken. Create a new one.')

def ifLoggedIn(test):

    if test.text.find(r'Central Authentication Service') == -1:

    #The login page of CAS will contain these words

        return True

    return False

            printWithTimeStamp('Parameters successfully acquired. wlanacip = '+wlanacip+', wlanuserip = '+wlanuserip)

            h={'Host': 'weblogin.sustc.edu.cn', 'Connection': 'keep-alive', 'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8', 'Upgrade-Insecure-Requests': '1' ,'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.112 Safari/537.36', 'DNT': '1', 'Accept-Encoding': 'gzip, deflate, sdch', 'Accept-Language': 'en-US,en;q=0.8,zh-CN;q=0.6,zh;q=0.4'}

            #Headers are acquired by capturing network traffic

            url='http://weblogin.sustc.edu.cn/cas/login?service=http%3A%2F%2Fenet.10000.gd.cn%3A10001%2Fsz%2Fsz112%2Findex.jsp%3Fwlanacip%3D'+wlanacip+'%26wlanuserip%3D'+wlanuserip

            #wlanacip & wlanuserip

            printWithTimeStamp('Start to get login information')

            lt=prelogin.text[start:end]

            end=lt.find(r'" />')

            lt=lt[0:end]

            #Get parameter "lt"

            start=prelogin.text.find(r'name="execution"')+24

            end=start+10

            execution=prelogin.text[start:end]

            end=execution.find(r'" />')

            execution=execution[0:end]

            #Get parameter "execution"

            start=prelogin.text.find(r'name="_eventId"')+23

            end=start+10

            _eventId=prelogin.text[start:end]

            end=_eventId.find(r'" />')

            _eventId=_eventId[0:end]

            #Get parameter "_eventld"

            end=prelogin.headers['Set-Cookie'].find(r'; Path=/cas/;')

            JSESSIONID_SUSTC= prelogin.headers['Set-Cookie'][11:end]

            #JSESSIONID stored in set-cookies

            printWithTimeStamp('Parameter JSESSIONID acquired. JSESSIONID = '+JSESSIONID_SUSTC)

            url='http://weblogin.sustc.edu.cn/cas/login;jsessionid='+JSESSIONID_SUSTC+'?service=http://enet.10000.gd.cn%3A10001%2Fsz%2Fsz112%2Findex.jsp%3Fwlanacip%3D'+wlanacip+'%26wlanuserip%3D'+wlanuserip

            username=config['username']

            passwd=config['password']

            #SUSTC CAS username (StudentID) and password

            data='username='+username+'&password='+passwd+'&lt='+lt+'&execution='+execution+'&_eventId='+_eventId+'&submit=LOGIN'

            h={'Host': 'weblogin.sustc.edu.cn', 'Connection': 'keep-alive', 'Cache-Control': 'max-age=0', 'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8', 'Origin': 'http://weblogin.sustc.edu.cn', 'Upgrade-Insecure-Requests': '1', 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.112 Safari/537.36', 'Content-Type': 'application/x-www-form-urlencoded', 'DNT': '1', 'Referer': url, 'Accept-Encoding': 'gzip, deflate', 'Accept-Language': 'en-US,en;q=0.8,zh-CN;q=0.6,zh;q=0.4'}

            #Acquired by capturing traffic

            cookies=dict({'Cookie': 'JSESSIONID='+JSESSIONID_SUSTC})

            login=requests.Session()

            #Use session to maintain cookies

            printWithTimeStamp('Login as '+username)

            login.post(url,data=data,headers=h,cookies=cookies)