How to construct a webob.Request or a WSGI 'environ' dict from raw HTTP request byte stream?

Question

Suppose I have a byte stream with the following in it:

POST /mum/ble?q=huh
Content-Length: 18
Content-Type: application/json; charset="utf-8"
Host: localhost:80

["do", "re", "mi"]

Is there a way to produce an WSGI-style 'environ' dict from it?

Hopefully, I've overlooked an easy answer, and it is as easy to achieve as the opposite operation. Consider:

>>> import json
>>> from webob import Request
>>> r = Request.blank('/mum/ble?q=huh')
>>> r.method = 'POST'
>>> r.content_type = 'application/json'
>>> r.charset = 'utf-8'
>>> r.body = json.dumps(['do', 're', 'mi'])
>>> print str(r) # Request's __str__ method gives raw HTTP bytes back!

POST /mum/ble?q=huh
Content-Length: 18
Content-Type: application/json; charset="utf-8"
Host: localhost:80

["do", "re", "mi"]

Answer 1

Reusing Python's standard library code for the purpose is a bit tricky (it was not designed to be reused that way!-), but should be doable, e.g:

import cStringIO
from wsgiref import simple_server, util

input_string = """POST /mum/ble?q=huh HTTP/1.0
Content-Length: 18
Content-Type: application/json; charset="utf-8"
Host: localhost:80

["do", "re", "mi"]
"""

class FakeHandler(simple_server.WSGIRequestHandler):
    def __init__(self, rfile):
        self.rfile = rfile
        self.wfile = cStringIO.StringIO() # for error msgs
        self.server = self
        self.base_environ = {}
        self.client_address = ['?', 80]
        self.raw_requestline = self.rfile.readline()
        self.parse_request()

    def getenv(self):
        env = self.get_environ()
        util.setup_testing_defaults(env)
        env['wsgi.input'] = self.rfile
        return env

handler = FakeHandler(rfile=cStringIO.StringIO(input_string))
wsgi_env = handler.getenv()

print wsgi_env

Basically, we need to subclass the request handler to fake out the construction process that's normally performed for it by the server (rfile and wfile built from the socket to the client, and so on). This isn't quite complete, I think, but should be close and I hope it proves helpful!

Note that I've also fixed your example HTTP request: without an HTTP/1.0 or 1.1 at the end of the raw request line, a POST is considered ill-formed and causes an exception and a resulting error message on handler.wfile.