python/lib/Lib/modjy/modjy_response.py

###
#
# Copyright Alan Kennedy. 
# 
# You may contact the copyright holder at this uri:
# 
# http://www.xhaus.com/contact/modjy
# 
# The licence under which this code is released is the Apache License v2.0.
# 
# The terms and conditions of this license are listed in a file contained
# in the distribution that also contained this file, under the name
# LICENSE.txt.
# 
# You may also read a copy of the license at the following web address.
# 
# http://modjy.xhaus.com/LICENSE.txt
#
###

import types

from java.lang import System

from modjy_exceptions import *
from modjy_write import write_object

# From: http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.5.1

hop_by_hop_headers = {
    'connection': None,
    'keep-alive': None,
    'proxy-authenticate': None,
    'proxy-authorization': None,
    'te': None,
    'trailers': None,
    'transfer-encoding': None,
    'upgrade': None,
}

class start_response_object:

    def __init__(self, req, resp):
        self.http_req = req
        self.http_resp = resp
        self.write_callable = None
        self.called = 0
        self.content_length = None

    # I'm doing the parameters this way to facilitate porting back to java
    def __call__(self, *args, **keywords):
        if len(args) < 2 or len(args) > 3:
            raise BadArgument("Start response callback requires either two or three arguments: got %s" % str(args))
        if len(args) == 3:
            exc_info = args[2]
            try:
                try:
                    self.http_resp.reset()
                except IllegalStateException, isx:
                    raise exc_info[0], exc_info[1], exc_info[2]
            finally:
                exc_info = None
        else:
            if self.called > 0:
                raise StartResponseCalledTwice("Start response callback may only be called once, without exception information.")
        status_str = args[0]
        headers_list = args[1]
        if not isinstance(status_str, types.StringType):
            raise BadArgument("Start response callback requires string as first argument")
        if not isinstance(headers_list, types.ListType):
            raise BadArgument("Start response callback requires list as second argument")
        try:
            status_code, status_message_str = status_str.split(" ", 1)
            self.http_resp.setStatus(int(status_code))
        except ValueError:
            raise BadArgument("Status string must be of the form '<int> <string>'")
        self.make_write_object()
        try:
            for header_name, header_value in headers_list:
                header_name_lower = header_name.lower()
                if hop_by_hop_headers.has_key(header_name_lower):
                    raise HopByHopHeaderSet("Under WSGI, it is illegal to set hop-by-hop headers, i.e. '%s'" % header_name)
                if header_name_lower == "content-length":
                    try:
                        self.set_content_length(int(header_value))
                    except ValueError, v:
                        raise BadArgument("Content-Length header value must be a string containing an integer, not '%s'" % header_value)
                else:
                    final_value = header_value.encode('latin-1')
                    # Here would be the place to check for control characters, whitespace, etc
                    self.http_resp.addHeader(header_name, final_value)
        except (AttributeError, TypeError), t:
            raise BadArgument("Start response callback headers must contain a list of (<string>,<string>) tuples")
        except UnicodeError, u:
            raise BadArgument("Encoding error: header values may only contain latin-1 characters, not '%s'" % repr(header_value))
        except ValueError, v:
            raise BadArgument("Headers list must contain 2-tuples")
        self.called += 1
        return self.write_callable

    def set_content_length(self, length):
        if self.write_callable.num_writes == 0:
            self.content_length = length
            self.http_resp.setContentLength(length)
        else:
            raise ResponseCommitted("Cannot set content-length: response is already commited.")

    def make_write_object(self):
        try:
            self.write_callable = write_object(self.http_resp.getOutputStream())
        except IOException, iox:
            raise IOError(iox)
        return self.write_callable