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185 lines
6.6 KiB
185 lines
6.6 KiB
2 years ago
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"""Manage HTTP Response Headers
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Much of this module is red-handedly pilfered from email.message in the stdlib,
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so portions are Copyright (C) 2001,2002 Python Software Foundation, and were
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written by Barry Warsaw.
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"""
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# Regular expression that matches `special' characters in parameters, the
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# existence of which force quoting of the parameter value.
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import re
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tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')
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def _formatparam(param, value=None, quote=1):
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"""Convenience function to format and return a key=value pair.
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This will quote the value if needed or if quote is true.
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"""
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if value is not None and len(value) > 0:
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if quote or tspecials.search(value):
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value = value.replace('\\', '\\\\').replace('"', r'\"')
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return '%s="%s"' % (param, value)
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else:
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return '%s=%s' % (param, value)
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else:
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return param
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class Headers:
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"""Manage a collection of HTTP response headers"""
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def __init__(self, headers=None):
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headers = headers if headers is not None else []
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if type(headers) is not list:
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raise TypeError("Headers must be a list of name/value tuples")
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self._headers = headers
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if __debug__:
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for k, v in headers:
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self._convert_string_type(k)
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self._convert_string_type(v)
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def _convert_string_type(self, value):
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"""Convert/check value type."""
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if type(value) is str:
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return value
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raise AssertionError("Header names/values must be"
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" of type str (got {0})".format(repr(value)))
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def __len__(self):
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"""Return the total number of headers, including duplicates."""
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return len(self._headers)
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def __setitem__(self, name, val):
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"""Set the value of a header."""
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del self[name]
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self._headers.append(
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(self._convert_string_type(name), self._convert_string_type(val)))
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def __delitem__(self,name):
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"""Delete all occurrences of a header, if present.
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Does *not* raise an exception if the header is missing.
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"""
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name = self._convert_string_type(name.lower())
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self._headers[:] = [kv for kv in self._headers if kv[0].lower() != name]
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def __getitem__(self,name):
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"""Get the first header value for 'name'
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Return None if the header is missing instead of raising an exception.
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Note that if the header appeared multiple times, the first exactly which
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occurrence gets returned is undefined. Use getall() to get all
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the values matching a header field name.
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"""
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return self.get(name)
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def __contains__(self, name):
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"""Return true if the message contains the header."""
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return self.get(name) is not None
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def get_all(self, name):
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"""Return a list of all the values for the named field.
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These will be sorted in the order they appeared in the original header
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list or were added to this instance, and may contain duplicates. Any
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fields deleted and re-inserted are always appended to the header list.
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If no fields exist with the given name, returns an empty list.
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"""
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name = self._convert_string_type(name.lower())
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return [kv[1] for kv in self._headers if kv[0].lower()==name]
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def get(self,name,default=None):
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"""Get the first header value for 'name', or return 'default'"""
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name = self._convert_string_type(name.lower())
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for k,v in self._headers:
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if k.lower()==name:
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return v
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return default
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def keys(self):
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"""Return a list of all the header field names.
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These will be sorted in the order they appeared in the original header
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list, or were added to this instance, and may contain duplicates.
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Any fields deleted and re-inserted are always appended to the header
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list.
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"""
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return [k for k, v in self._headers]
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def values(self):
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"""Return a list of all header values.
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These will be sorted in the order they appeared in the original header
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list, or were added to this instance, and may contain duplicates.
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Any fields deleted and re-inserted are always appended to the header
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list.
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"""
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return [v for k, v in self._headers]
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def items(self):
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"""Get all the header fields and values.
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These will be sorted in the order they were in the original header
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list, or were added to this instance, and may contain duplicates.
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Any fields deleted and re-inserted are always appended to the header
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list.
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"""
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return self._headers[:]
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def __repr__(self):
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return "%s(%r)" % (self.__class__.__name__, self._headers)
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def __str__(self):
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"""str() returns the formatted headers, complete with end line,
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suitable for direct HTTP transmission."""
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return '\r\n'.join(["%s: %s" % kv for kv in self._headers]+['',''])
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def __bytes__(self):
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return str(self).encode('iso-8859-1')
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def setdefault(self,name,value):
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"""Return first matching header value for 'name', or 'value'
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If there is no header named 'name', add a new header with name 'name'
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and value 'value'."""
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result = self.get(name)
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if result is None:
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self._headers.append((self._convert_string_type(name),
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self._convert_string_type(value)))
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return value
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else:
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return result
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def add_header(self, _name, _value, **_params):
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"""Extended header setting.
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_name is the header field to add. keyword arguments can be used to set
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additional parameters for the header field, with underscores converted
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to dashes. Normally the parameter will be added as key="value" unless
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value is None, in which case only the key will be added.
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Example:
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h.add_header('content-disposition', 'attachment', filename='bud.gif')
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Note that unlike the corresponding 'email.message' method, this does
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*not* handle '(charset, language, value)' tuples: all values must be
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strings or None.
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"""
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parts = []
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if _value is not None:
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_value = self._convert_string_type(_value)
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parts.append(_value)
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for k, v in _params.items():
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k = self._convert_string_type(k)
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if v is None:
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parts.append(k.replace('_', '-'))
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else:
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v = self._convert_string_type(v)
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parts.append(_formatparam(k.replace('_', '-'), v))
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self._headers.append((self._convert_string_type(_name), "; ".join(parts)))
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