import re
import logging
from wsgiref.util import is_hop_by_hop
# List containing string constants that are used to represent headers
# that can be ignored in the required_header function
IGNORE_HEADERS = (
'HTTP_ACCEPT_ENCODING', # We want content to be uncompressed so we remove the Accept-Encoding from original request
'HTTP_HOST',
'HTTP_REMOTE_USER',
)
# Default from HTTP RFC 2616
# See: http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.7.1
#: Variable that represent the default charset used
DEFAULT_CHARSET = 'latin-1'
#: List containing string constants that represents possible html content type
HTML_CONTENT_TYPES = (
'text/html',
'application/xhtml+xml'
)
#: Variable used to represent a minimal content size required for response
#: to be turned into stream
MIN_STREAMING_LENGTH = 4 * 1024 # 4KB
#: Regex used to find charset in a html content type
_get_charset_re = re.compile(r';\s*charset=(?P<charset>[^\s;]+)', re.I)
def is_html_content_type(content_type):
"""
Function used to verify if the parameter is a proper html content type
:param content_type: String variable that represent a content-type
:returns: A boolean value stating if the content_type is a valid html content type
"""
for html_content_type in HTML_CONTENT_TYPES:
if content_type.startswith(html_content_type):
return True
return False
def should_stream(proxy_response):
"""
Function to verify if the proxy_response must be converted into
a stream. This will be done by checking the proxy_response content-length
and verify if its length is bigger than one stipulated by MIN_STREAMING_LENGTH.
:param proxy_response: An Instance of urllib3.response.HTTPResponse
:returns: A boolean stating if the proxy_response should be treated as a stream
"""
content_type = proxy_response.headers.get('Content-Type')
if is_html_content_type(content_type):
return False
try:
content_length = int(proxy_response.headers.get('Content-Length', 0))
except ValueError:
content_length = 0
if not content_length or content_length > MIN_STREAMING_LENGTH:
return True
return False
def get_charset(content_type):
"""
Function used to retrieve the charset from a content-type. If there is no charset in the content type
then the charset defined on DEFAULT_CHARSET will be returned.
:param content_type: A string containing a Content-Type header
:returns: A string containing the charset
"""
if not content_type:
return DEFAULT_CHARSET
matched = _get_charset_re.search(content_type)
if matched:
# Extract the charset and strip its double quotes
return matched.group('charset').replace('"', '')
return DEFAULT_CHARSET
def required_header(header):
"""
Function that verifies if the header parameter is a essential header.
:param header: A string represented a header
:returns: A boolean value that represent if the header is required
"""
if header in IGNORE_HEADERS:
return False
if header.startswith('HTTP_') or header == 'CONTENT_TYPE':
return True
return False
def set_response_headers(response, response_headers):
for header, value in response_headers.items():
if is_hop_by_hop(header) or header.lower() == 'set-cookie':
continue
response[header.title()] = value
logger.debug('Response headers: %s', getattr(response, '_headers'))
def normalize_request_headers(request):
"""
Function used to transform headers, replacing 'HTTP\_' to '' and replace '_' to '-'.
:param request: A HttpRequest that will be transformed
:returns: A dictionary with the normalized headers
"""
norm_headers = {}
for header, value in request.META.items():
if required_header(header):
norm_header = header.replace('HTTP_', '').title().replace('_', '-')
norm_headers[norm_header] = value
return norm_headers
def encode_items(items):
"""
Function that encode all elements in the list of items passed as a parameter.
:param items: A list of tuple
:returns: A list of tuple with all items encoded in 'utf-8'
"""
encoded = []
for key, values in items:
for value in values:
encoded.append((key.encode('utf-8'), value.encode('utf-8')))
return encoded
logger = logging.getLogger(__name__ + '.cookies')
def cookie_from_string(cookie_string):
"""
Parser for HTTP header set-cookie.
The return from this function will be used as parameters for django's response.set_cookie method.
Because set_cookie doesn't have parameter comment, this cookie attribute will be ignored.
:param cookie_string: A string representing a valid cookie
:returns: A dictionary containing the cookie_string attributes
"""
valid_attrs = ('path', 'domain', 'comment', 'expires', 'max_age', 'httponly', 'secure')
cookie_dict = {}
cookie_parts = cookie_string.split(';')
try:
cookie_dict['key'], cookie_dict['value'] = cookie_parts[0].split('=')
except ValueError:
logger.warning('Invalid cookie: `%s`', cookie_string)
return None
for part in cookie_parts[1:]:
if '=' in part:
try:
attr, value = part.split('=')
except ValueError:
logger.warning('Invalid cookie attribute: `%s`', part)
continue
value = value.strip()
else:
attr = part
value = ''
attr = attr.strip().lower()
if not attr:
continue
if attr in valid_attrs:
if attr in ('httponly', 'secure'):
cookie_dict[attr] = True
elif attr in 'comment':
# ignoring comment attr as explained in the function docstring
continue
else:
cookie_dict[attr] = value
else:
logger.warning('Unknown cookie attribute %s', attr)
return cookie_dict
