util.py

Mod_python is an Apache module that embeds the Python interpreter within the server. With mod_python

 # vim: set sw=4 expandtab :
 #
 # Copyright 2004 Apache Software Foundation
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you
 # may not use this file except in compliance with the License.  You
 # may obtain a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 # implied.  See the License for the specific language governing
 # permissions and limitations under the License.
 #
 # Originally developed by Gregory Trubetskoy.
 #
 # $Id: util.py 478129 2006-11-22 11:15:54Z grahamd $

import _apache
import apache
import cStringIO
import tempfile
import re

from types import *
from exceptions import *

parse_qs = _apache.parse_qs
parse_qsl = _apache.parse_qsl

# Maximum line length for reading. (64KB)
# Fixes memory error when upload large files such as 700+MB ISOs.
readBlockSize = 65368

""" The classes below are a (almost) a drop-in replacement for the
    standard cgi.py FieldStorage class. They should have pretty much the
    same functionality.

    These classes differ in that unlike cgi.FieldStorage, they are not
    recursive. The class FieldStorage contains a list of instances of
    Field class. Field class is incapable of storing anything in it.

    These objects should be considerably faster than the ones in cgi.py
    because they do not expect CGI environment, and are
    optimized specifically for Apache and mod_python.
"""

class Field:
    def __init__(self, name, *args, **kwargs):
        self.name = name

        # Some third party packages such as Trac create
        # instances of the Field object and insert it
        # directly into the list of form fields. To
        # maintain backward compatibility check for
        # where more than just a field name is supplied
        # and invoke an additional initialisation step
        # to process the arguments. Ideally, third party
        # code should use the add_field() method of the
        # form, but if they need to maintain backward
        # compatibility with older versions of mod_python
        # they will not have a choice but to use old
        # way of doing things and thus we need this code
        # for the forseeable future to cope with that.

        if args or kwargs:
            self.__bc_init__(*args, **kwargs)

    def __bc_init__(self, file, ctype, type_options,
                    disp, disp_options, headers = {}):
       self.file = file
       self.type = ctype
       self.type_options = type_options
       self.disposition = disp
       self.disposition_options = disp_options
       if disp_options.has_key("filename"):
           self.filename = disp_options["filename"]
       else:
           self.filename = None
       self.headers = headers

    def __repr__(self):
        """Return printable representation."""
        return "Field(%s, %s)" % (`self.name`, `self.value`)

    def __getattr__(self, name):
        if name != 'value':
            raise AttributeError, name
        if self.file:
            self.file.seek(0)
            value = self.file.read()
            self.file.seek(0)
        else:
            value = None
        return value

    def __del__(self):
        self.file.close()

class StringField(str):
    """ This class is basically a string with
    added attributes for compatibility with std lib cgi.py. Basically, this
    works the opposite of Field, as it stores its data in a string, but creates
    a file on demand. Field creates a value on demand and stores data in a file.
    """
    filename = None
    headers = {}
    ctype = "text/plain"
    type_options = {}
    disposition = None
    disp_options = None
    
    # I wanted __init__(name, value) but that does not work (apparently, you
    # cannot subclass str with a constructor that takes >1 argument)
    def __init__(self, value):
        '''Create StringField instance. You'll have to set name yourself.'''
        str.__init__(self, value)
        self.value = value

    def __getattr__(self, name):
        if name != 'file':
            raise AttributeError, name
        self.file = cStringIO.StringIO(self.value)
        return self.file
        
    def __repr__(self):
        """Return printable representation (to pass unit tests)."""
        return "Field(%s, %s)" % (`self.name`, `self.value`)

class FieldList(list):

    def __init__(self):
        self.__table = None
        list.__init__(self)

    def table(self):
        if self.__table is None:
            self.__table = {}
            for item in self:
                if item.name in self.__table:
                    self.__table[item.name].append(item)
                else:
                    self.__table[item.name] = [item]
        return self.__table

    def __delitem__(self, *args):
        self.__table = None
        return list.__delitem__(self, *args)

    def __delslice__(self, *args):
        self.__table = None
        return list.__delslice__(self, *args)

    def __iadd__(self, *args):
        self.__table = None
        return list.__iadd__(self, *args)

    def __imul__(self, *args):
        self.__table = None
        return list.__imul__(self, *args)

    def __setitem__(self, *args):
        self.__table = None
        return list.__setitem__(self, *args)

    def __setslice__(self, *args):
        self.__table = None
        return list.__setslice__(self, *args)

    def append(self, *args):
        self.__table = None
        return list.append(self, *args)

    def extend(self, *args):
        self.__table = None
        return list.extend(self, *args)

    def insert(self, *args):
        self.__table = None
        return list.insert(self, *args)

    def pop(self, *args):
        self.__table = None
        return list.pop(self, *args)

    def remove(self, *args):
        self.__table = None
        return list.remove(self, *args)


class FieldStorage:

    def __init__(self, req, keep_blank_values=0, strict_parsing=0, file_callback=None, field_callback=None):
        #
        # Whenever readline is called ALWAYS use the max size EVEN when
        # not expecting a long line. - this helps protect against
        # malformed content from exhausting memory.
        #

        self.list = FieldList()

        # always process GET-style parameters
        if req.args:
            pairs = parse_qsl(req.args, keep_blank_values)
            for pair in pairs:
                self.add_field(pair[0], pair[1])

        if req.method != "POST":
            return

        try:
            clen = int(req.headers_in["content-length"])
        except (KeyError, ValueError):
            # absent content-length is not acceptable
            raise apache.SERVER_RETURN, apache.HTTP_LENGTH_REQUIRED

        if not req.headers_in.has_key("content-type"):
            ctype = "application/x-www-form-urlencoded"
        else:
            ctype = req.headers_in["content-type"]

        if ctype.startswith("application/x-www-form-urlencoded"):
            pairs = parse_qsl(req.read(clen), keep_blank_values)
            for pair in pairs:
                self.add_field(pair[0], pair[1])
            return

        if not ctype.startswith("multipart/"):
            # we don't understand this content-type
            raise apache.SERVER_RETURN, apache.HTTP_NOT_IMPLEMENTED

        # figure out boundary
        try:
            i = ctype.lower().rindex("boundary=")
            boundary = ctype[i+9:]
            if len(boundary) >= 2 and boundary[0] == boundary[-1] == '"':
                boundary = boundary[1:-1]
            boundary = re.compile("--" + re.escape(boundary) + "(--)?\r?\n") 

        except ValueError:
            raise apache.SERVER_RETURN, apache.HTTP_BAD_REQUEST

        # read until boundary
        self.read_to_boundary(req, boundary, None)

        end_of_stream = False
        while not end_of_stream: # jjj JIM BEGIN WHILE
            ## parse headers

            ctype, type_options = "text/plain", {}
            disp, disp_options = None, {}
            headers = apache.make_table()

            line = req.readline(readBlockSize)
            match = boundary.match(line)
            if (not line) or match:
                # we stop if we reached the end of the stream or a stop
                # boundary (which means '--' after the boundary) we
                # continue to the next part if we reached a simple
                # boundary in either case this would mean the entity is
                # malformed, but we're tolerating it anyway.
                end_of_stream = (not line) or (match.group(1) is not None)
                continue
  
            skip_this_part = False
            while line not in ('\r','\r\n'):
                nextline = req.readline(readBlockSize)
                while nextline and nextline[0] in [ ' ', '\t']:
                    line = line + nextline
                    nextline = req.readline(readBlockSize)
                # we read the headers until we reach an empty line
                # NOTE : a single \n would mean the entity is malformed, but
                # we're tolerating it anyway
                h, v = line.split(":", 1)
                headers.add(h, v)
                h = h.lower()
                if h == "content-disposition":
                    disp, disp_options = parse_header(v)
                elif h == "content-type":
                    ctype, type_options = parse_header(v)
                    #
                    # NOTE: FIX up binary rubbish sent as content type
                    # from Microsoft IE 6.0 when sending a file which
                    # does not have a suffix.
                    #
                    if ctype.find('/') == -1:
                        ctype = 'application/octet-stream'