检查网站是否正常工作时如何绕过或捕获socket.timeout的错误？

Question

我一直在开发一个程序来检查网站是否正常工作。 我从Excel工作表中获取URL，然后在同一个Excel工作表中将结果粘贴为True和false但是对于某些URL，我收到socket.timeout错误，之后代码无效。 这是代码：

   import http.client as httpc
from urllib.parse import urlparse
import pandas as pd
import xlwings as xw
import smtplib
from xlsxwriter import Workbook


import socket


x=[]

df = pd.read_excel (r'xyz.xlsx')
df1=pd.DataFrame(df,columns=['URL'])
print(df1)
url_list=df["URL"].tolist()
print(url_list)
for i in url_list:
    def checkUrl(i):
        if 'http' not in i:
            i= 'https://'+i
        p = urlparse(i)
        conn = httpc.HTTPConnection(p.netloc,timeout=4)
        conn.request('HEAD', p.path)
        try:
            resp = conn.getresponse()
            return resp.status<400
        except requests.exceptions.RequestException:
            return False
    print(checkUrl(i))
    x.append(checkUrl(i))


workbook = Workbook('abc.xlsx')
Report_Sheet = workbook.add_worksheet()
Report_Sheet.write(0, 1, 'Value')
Report_Sheet.write_column(1, 1, x)

workbook.close()

Answer 1

这段代码有很多问题。

1. 即使url需要HTTPS，你也无法使用HTTP
2. 你执行try:的请求try:
3. except子句期望您的代码不能抛出requests.exceptions.RequestException

由于您没有使用请求库，而是低级别的http.client ，您应该只期待来自套接字库的错误，这些错误都是OSError的子类

您的代码可能会变成（小心：未经测试）：

def checkUrl(i):
    if 'http' not in i:
        i= 'https://'+i
    p = urlparse(i)
    if (p.scheme == 'http'):
        conn = httpc.HTTPConnection(p.netloc,timeout=4)
    else:
        conn = httpc.HTTPSConnection(p.netloc,timeout=4)
    try:
        conn.request('HEAD', p.path)
        resp = conn.getresponse()
        return resp.status<400
    except OSError:
        return False

Answer 2

根据我的经验，当IP地址解析为有效主机名时会发生此错误，但服务器不再配置为使用该主机名。 这会导致服务器忽略您尝试连接到它的尝试。

要处理此问题，您应该在超时错误时返回False。

    import socket

    try:
        resp = conn.getresponse()
        return resp.status<400
    except requests.exceptions.RequestException:
        return False
    except socket.timeout as err:
        return False

您将需要检查http.client.HTTPException而不是requests.exceptions.RequestException因为您正在执行的此检查使用http.client库而不是requests库。 此外，您还需要捕获以下所有错误。

    import socket
    import ssl
    import http.client

    try:
        resp = conn.getresponse()
        return resp.status < 400
    except http.client.HTTPException as err:
        # A connection was established, but the request failed
        return False 
    except socket.timeout as err:
        # The website no longer exists on the server
        return False
    except socket.gaierror as err:
        # Could not resolve the hostname to an IP address
        return False
    except ssl.CertificateError as err:
        # The SSL certificate was never configured, or it cannot be trusted
        return False
    except ssl.SSLError as err:
        # Other SSL errors not covered by ssl.CertificateError
        return False

Answer 3

首先猜测的是

resp = conn.getresponse()

应该在try子句中。 如果这不起作用，请添加程序的输出。