Python 3中从服务器返回响应时引发BadStatusLine异常

7

我正在尝试将一个提交XML feeds的脚本移植到Python 3,该脚本可以在此处找到:

https://developers.google.com/search-appliance/documentation/files/pushfeed_client.py.txt

运行2to3.py并作出一些小调整以消除任何语法错误后,脚本失败并显示以下内容:

(py33dev) d:\dev\workspace>python pushfeed_client.py --datasource="TEST1" --feedtype="full" --url="http://gsa:19900/xmlfeed" --xmlfilename="test.xml"
Traceback (most recent call last):
  File "pushfeed_client.py", line 108, in <module>
    main(sys.argv)
  File "pushfeed_client.py", line 56, in main
    result = urllib.request.urlopen(request_url)
  File "C:\Python33\Lib\urllib\request.py", line 156, in urlopen
    return opener.open(url, data, timeout)
  File "C:\Python33\Lib\urllib\request.py", line 469, in open
    response = self._open(req, data)
  File "C:\Python33\Lib\urllib\request.py", line 487, in _open
    '_open', req)
  File "C:\Python33\Lib\urllib\request.py", line 447, in _call_chain
    result = func(*args)
  File "C:\Python33\Lib\urllib\request.py", line 1268, in http_open
    return self.do_open(http.client.HTTPConnection, req)
  File "C:\Python33\Lib\urllib\request.py", line 1253, in do_open
    r = h.getresponse()
  File "C:\Python33\Lib\http\client.py", line 1147, in getresponse
    response.begin()
  File "C:\Python33\Lib\http\client.py", line 358, in begin
    version, status, reason = self._read_status()
  File "C:\Python33\Lib\http\client.py", line 340, in _read_status
    raise BadStatusLine(line)
http.client.BadStatusLine: <!DOCTYPE html>

为什么响应服务器后会返回那个异常?以下是我监听会话时从GSA获取的完整响应:

<!DOCTYPE html>
<html lang=en>
  <meta charset=utf-8>
  <meta name=viewport content="initial-scale=1, minimum-scale=1, width=device-width">
  <title>Error 400 (Bad Request)!!1</title>
  <style>
    *{margin:0;padding:0}html,code{font:15px/22px arial,sans-serif}html{background:#fff;color:#222;padding:15px}body{margin:7% auto 0;max-width:390px;min-height:180px;padding:30px 0 15px}* > body{background:url(//www.google.com/images/errors/robot.png) 100% 5px no-repeat;padding-right:205px}p{margin:11px 0 22px;overflow:hidden}ins{color:#777;text-decoration:none}a img{border:0}@media screen and (max-width:772px){body{background:none;margin-top:0;max-width:none;padding-right:0}}
  </style>
  <a href=//www.google.com/><img src=//www.google.com/images/errors/logo_sm.gif alt=Google></a>
  <p><b>400.</b> <ins>That’s an error.</ins>
  <p>Your client has issued a malformed or illegal request.  <ins>That’s all we know.</ins>

它确实返回了HTTP 400错误。每当XML负载中有utf-8字符时,我都可以可靠地引起此问题。当它是纯ASCII时,它运行得非常完美。这里是我可以使用的最基本版本的代码,可以可靠地重新创建该问题:

import http.client
http.client.HTTPConnection.debuglevel = 1
with open("GSA_full_Feed.xml", encoding='utf-8') as xdata:
    payload = xdata.read()
content_length = len(payload)
feed_path = "xmlfeed"
content_type = "multipart/form-data; boundary=----------boundary_of_feed_data$"
headers = {"Content-type": content_type, "Content-length": content_length}
conn = http.client.HTTPConnection("gsa", 19900)
conn.request("POST", feed_path, body=payload.encode("utf-8"), headers=headers)
res = conn.getresponse()
print(res.read())
conn.close()

以下是用于引发异常的示例XML负载:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE gsafeed PUBLIC "-//Google//DTD GSA Feeds//EN" "gsafeed.dtd">
<gsafeed>
  <header>
    <datasource>TEST1</datasource>
    <feedtype>full</feedtype>
  </header>
  <group>
    <record action="add" mimetype="text/html" url="https://myschweetassurl.com">
      <metadata>
        <meta content="shit happens, then you die" name="description"/>
      </metadata>
      <content>wacky Umläut test of non utf-8 characters</content>
    </record>
  </group>
</gsafeed>

我发现Python 2和3之间唯一的不同之处在于每个请求的content-length头部。Python 3版本始终比2版本短,分别为870和873。

1个回答

8

经过大量的wiresharking,我找出了问题的原因和解决方法,这是由于设置content-length头文件的方式不当。在我的Python 3版本脚本中,我复制了设置content-length的方法,该方法如下:

headers['Content-length']=str(len(body))

这是错误的!正确的方式应该是这样的:
headers['Content-length']=str(len(bytes(body, 'utf-8')))

因为有效载荷必须是字节对象。当您对其进行字节编码时,长度与字符串版本不同。

return urllib.request.Request(theurl, bytes(body, 'utf-8'), headers)

使用任何源自http.client.HTTPConnection的东西时,可以安全地省略手动设置content-length头。它具有内部方法,用于检查content-length头,如果缺少,则根据内容主体的长度设置它,而不管其形式。
问题在于Python 2和3之间的翻译存在微妙的差异以及它如何处理字符串并对其进行编码。当utf-8版本无法正常工作时,普通的ASCII版本可能是某种偶然情况,哦,好吧。

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