在 python 中使用已连接的 wifi 检查互联网连接可用性

Question

I hope I can find some help here. After searching for possibilities to "check whether an internet connection is available with python" I found various way to perform that check. However, those proposed ways does not work for me and I have no clue, why it doesn't so I am seeking for some advice.

The setup:
I have a Pi4 and running Raspap, to open up a Hotspot, which I can access via a static IP address. Raspap is configured to connect to a wifi LTE router to get internet connectivity. I am using this Pi4 in a headless mode and using Raspap to access the Pi or to configure a different Wifi network than the wifi LTE router one.

I have a python script running to check for files in a folder and upload them to a cloud service, if a internet connection is available and renames the files afterwards. Before I have setup Raspap, the Pi was only connected to a wifi or not and my check for internet connectivity was working.

The scenario:
The mobile LTE router does not have a SIM card inserted, so the PI4 is connected to the mobile LTE routers wifi, but there is no internet access. In this case the python script should recognize, that there is no internet connectivity and does not upload any files. However, the if condition for the wifi check is still true, of course the upload is not working, but the script performs the renaming afterwards.

The python script for uploading and renaming looks like this:

def upload():
    # run a function to check a folder for files without a "X_" prefix and put it to an uploadQueue (as an global array)
    retrieveFilesForUpload(uploadFolder, 60, olderThanXDays=olderThanXDays)
    
    # if upload queue contains files and  the Pi is connected to the internet, then upload the files
    if len(uploadQueue)>0 and isConnectedToInternet():
        # the retrieveAndUpload function uses the global array as input
        upload = threading.Thread(target=retrieveAndUpload)
        upload.start()
        upload.join()

        # after uploading the file, rename it by adding a Prefix "X_" 
        renameUploadedFiles(uploadFolder)

The "isConnectedToInternet()" function looks like one of these (they have a number at the end for testing the different ways):

def isConnectedWithInternet0():
    try:
        socket.create_connection(("1.1.1.1", 53))
        return True
    except OSError:
        pass
    return False

def isConnectedWithInternet2():
    for timeout in [1, 5, 10, 15]:
        print("timeout:", timeout)
        try:
            socket.setdefaulttimeout(timeout)
            host = socket.gethostbyname("www.google.com")
            s = socket.create_connection((host, 443), 2)
            s.close()
            print("Internet connection available")
            return True
        except OSError:
            print("No Internet")
            pass
    return False

def isConnectedWithInternet():
    import requests
    timeout = 2
    url = "http://8.8.8.8"
    try: 
        request = requests.head(url, timeout=timeout)
        print("Function 3: Connected to internet")
        return True
    except (requests.ConnectionError, requests.Timeout) as exception:
        print("Function 3: no Internet")
        return False

def isConnectedWithInternet4():
    host = "8.8.8.8"
    port = 53
    result = ""
    try:
        socket.setdefaulttimeout(2)
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((host, port))
        #return True
    except socket.error as ex:
        print(ex)
        return False
    else:
        s.close()
        return True
    #return result

def isConnectedWithInternet5():
    import urllib.request
    try: 
        urllib.request.urlopen("http://216.58.192.142", timeout=1)
        return True
    except urllib.request.error as err:
        print(err)
        return False

def isConnectedWithInternet6():
    try:
        import httplib
    except:
        import http.client as httplib

    timeout = 2
    url = "www.google.com"
    conn = httplib.HTTPConnection(url, timeout=timeout)
    try:
        conn.request("HEAD", "/")
        conn.close()
        return True
    except Exception as e:
        print(e)
        return False

But although the Wifi is connected to a wifi LTE router with no SIM card inserted (there is no internet connection), I always get True as a result, no matter what function above I am using.

I hope somebody can give me a hint/advice/some help on this issue.

Thank you very much!

Best Khaniii

Answer 1

This may help you.

import requests

url = "http://www.google.com"
timeout = 5
try:
    request = requests.get(url, timeout=timeout)
    print("Connected to the Internet")
except (requests.ConnectionError, requests.Timeout) as exception:
    print("No internet connection.")

Answer 2

You can test ping to an internet server. This worked for me while monitoring my internet connexion:

import platform    # For getting the operating system name
import subprocess  # For executing a shell command
import re

def ping(host):
    results = []
    param = '-n' if platform.system().lower()=='windows' else '-c'
    command = ['ping', param, '1', host]
    output = subprocess.Popen(command, stdout=subprocess.PIPE).stdout.read()
    result = re.findall("=\ (\d+)ms", str(output))
    results.append(result)
    return results

ping('8.8.8.8')

this returns the ping values in a list or empty list if no ping answer

[['6', '6', '6']]
or
[[]]