在Python中创建和解析多部分HTTP请求

Question

我正在尝试编写一些python代码,可以在客户端创建多部分mime http请求,然后在服务器上进行适当的解释.我认为,我在客户端部分取得了成功:

from email.mime.multipart import MIMEMultipart, MIMEBase
import httplib
h1 = httplib.HTTPConnection('localhost:8080')
msg = MIMEMultipart()
fp = open('myfile.zip', 'rb')
base = MIMEBase("application", "octet-stream")
base.set_payload(fp.read())
msg.attach(base)
h1.request("POST", "http://localhost:8080/server", msg.as_string())

唯一的问题是电子邮件库还包括Content-Type和MIME-Version标头,我不确定它们将如何与httplib包含的HTTP标头相关:

Content-Type: multipart/mixed; boundary="===============2050792481=="
MIME-Version: 1.0

--===============2050792481==
Content-Type: application/octet-stream
MIME-Version: 1.0

这可能是我的web.py应用程序收到此请求时,我收到错误消息的原因.web.py POST处理程序:

class MultipartServer:
    def POST(self, collection):
        print web.input()

抛出此错误:

Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/application.py", line 242, in process
    return self.handle()
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/application.py", line 233, in handle
    return self._delegate(fn, self.fvars, args)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/application.py", line 415, in _delegate
    return handle_class(cls)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/application.py", line 390, in handle_class
    return tocall(*args)
  File "/home/richard/Development/server/webservice.py", line 31, in POST
    print web.input()
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/webapi.py", line 279, in input
    return storify(out, *requireds, **defaults)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/utils.py", line 150, in storify
    value = getvalue(value)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/utils.py", line 139, in getvalue
    return unicodify(x)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/utils.py", line 130, in unicodify
    if _unicode and isinstance(s, str): return safeunicode(s)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.34-py2.6.egg/web/utils.py", line 326, in safeunicode
    return obj.decode(encoding)
  File "/usr/lib/python2.6/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode bytes in position 137-138: invalid data

我的代码行由大约一半的错误行表示:

  File "/home/richard/Development/server/webservice.py", line 31, in POST
    print web.input()

它来了,但我不知道从哪里开始.这是我的客户端代码的问题,还是web.py的限制(也许它只是不支持多部分请求)？将非常感激地收到替代代码库的任何提示或建议.

编辑

上述错误是由于数据未自动进行base64编码引起的.添加

encoders.encode_base64(base)

摆脱这个错误,现在问题很明显.HTTP请求未在服务器中正确解释,可能是因为电子邮件库包含了身体中应该是HTTP标头的内容:

<Storage {'Content-Type: multipart/mixed': u'', 
          ' boundary': u'"===============1342637378=="\n'
          'MIME-Version: 1.0\n\n--===============1342637378==\n'
          'Content-Type: application/octet-stream\n'
          'MIME-Version: 1.0\n' 
          'Content-Transfer-Encoding: base64\n'
          '\n0fINCs PBk1jAAAAAAAAA.... etc

所以有些东西不对.

谢谢

理查德

Answer 1

经过一番探索，这个问题的答案已经很清楚了。简短的回答是，虽然Content-Disposition 是可选的在 Mime 编码消息中是可选的，但 web.py 需要为每个 mime 部分提供它，以便正确解析 HTTP 请求。

与这个问题的其他评论相反，HTTP 和电子邮件之间的区别是无关紧要的，因为它们只是 Mime 消息的传输机制，仅此而已。多部分/相关（不是多部分/表单数据）消息在内容交换 Web 服务中很常见，这就是此处的用例。不过，提供的代码片段是准确的，并且使我对问题有了稍微简短的解决方案。

# open an HTTP connection
h1 = httplib.HTTPConnection('localhost:8080')

# create a mime multipart message of type multipart/related
msg = MIMEMultipart("related")

# create a mime-part containing a zip file, with a Content-Disposition header
# on the section
fp = open('file.zip', 'rb')
base = MIMEBase("application", "zip")
base['Content-Disposition'] = 'file; name="package"; filename="file.zip"'
base.set_payload(fp.read())
encoders.encode_base64(base)
msg.attach(base)

# Here's a rubbish bit: chomp through the header rows, until hitting a newline on
# its own, and read each string on the way as an HTTP header, and reading the rest
# of the message into a new variable
header_mode = True
headers = {}
body = []
for line in msg.as_string().splitlines(True):
    if line == "\n" and header_mode == True:
        header_mode = False
    if header_mode:
        (key, value) = line.split(":", 1)
        headers[key.strip()] = value.strip()
    else:
        body.append(line)
body = "".join(body)

# do the request, with the separated headers and body
h1.request("POST", "http://localhost:8080/server", body, headers)

web.py 很好地实现了这一点，因此很明显，email.mime.multipart 适合创建要通过 HTTP 传输的 Mime 消息，但其标头处理除外。

我的另一个总体担忧是可扩展性。这个解决方案和这里提出的其他解决方案都不能很好地扩展，因为它们在捆绑到 mime 消息中之前将文件的内容读入变量中。更好的解决方案是当内容通过 HTTP 连接传输时可以按需序列化。对我来说解决这个问题并不紧急，但如果我能找到解决方案，我会带着解决方案回来。