1 """Manage HTTP Response Headers
2
3 Much of this module is red-handedly pilfered from email.message in the stdlib,
4 so portions are Copyright (C) 2001,2002 Python Software Foundation, and were
5 written by Barry Warsaw.
6 """
7
8 # Regular expression that matches `special' characters in parameters, the
9 # existence of which force quoting of the parameter value.
10 import re
11 tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')
12
13 def _formatparam(param, value=None, quote=1):
14 """Convenience function to format and return a key=value pair.
15
16 This will quote the value if needed or if quote is true.
17 """
18 if value is not None and len(value) > 0:
19 if quote or tspecials.search(value):
20 value = value.replace('\\', '\\\\').replace('"', r'\"')
21 return '%s="%s"' % (param, value)
22 else:
23 return '%s=%s' % (param, value)
24 else:
25 return param
26
27
28 class ESC[4;38;5;81mHeaders:
29 """Manage a collection of HTTP response headers"""
30
31 def __init__(self, headers=None):
32 headers = headers if headers is not None else []
33 if type(headers) is not list:
34 raise TypeError("Headers must be a list of name/value tuples")
35 self._headers = headers
36 if __debug__:
37 for k, v in headers:
38 self._convert_string_type(k)
39 self._convert_string_type(v)
40
41 def _convert_string_type(self, value):
42 """Convert/check value type."""
43 if type(value) is str:
44 return value
45 raise AssertionError("Header names/values must be"
46 " of type str (got {0})".format(repr(value)))
47
48 def __len__(self):
49 """Return the total number of headers, including duplicates."""
50 return len(self._headers)
51
52 def __setitem__(self, name, val):
53 """Set the value of a header."""
54 del self[name]
55 self._headers.append(
56 (self._convert_string_type(name), self._convert_string_type(val)))
57
58 def __delitem__(self,name):
59 """Delete all occurrences of a header, if present.
60
61 Does *not* raise an exception if the header is missing.
62 """
63 name = self._convert_string_type(name.lower())
64 self._headers[:] = [kv for kv in self._headers if kv[0].lower() != name]
65
66 def __getitem__(self,name):
67 """Get the first header value for 'name'
68
69 Return None if the header is missing instead of raising an exception.
70
71 Note that if the header appeared multiple times, the first exactly which
72 occurrence gets returned is undefined. Use getall() to get all
73 the values matching a header field name.
74 """
75 return self.get(name)
76
77 def __contains__(self, name):
78 """Return true if the message contains the header."""
79 return self.get(name) is not None
80
81
82 def get_all(self, name):
83 """Return a list of all the values for the named field.
84
85 These will be sorted in the order they appeared in the original header
86 list or were added to this instance, and may contain duplicates. Any
87 fields deleted and re-inserted are always appended to the header list.
88 If no fields exist with the given name, returns an empty list.
89 """
90 name = self._convert_string_type(name.lower())
91 return [kv[1] for kv in self._headers if kv[0].lower()==name]
92
93
94 def get(self,name,default=None):
95 """Get the first header value for 'name', or return 'default'"""
96 name = self._convert_string_type(name.lower())
97 for k,v in self._headers:
98 if k.lower()==name:
99 return v
100 return default
101
102
103 def keys(self):
104 """Return a list of all the header field names.
105
106 These will be sorted in the order they appeared in the original header
107 list, or were added to this instance, and may contain duplicates.
108 Any fields deleted and re-inserted are always appended to the header
109 list.
110 """
111 return [k for k, v in self._headers]
112
113 def values(self):
114 """Return a list of all header values.
115
116 These will be sorted in the order they appeared in the original header
117 list, or were added to this instance, and may contain duplicates.
118 Any fields deleted and re-inserted are always appended to the header
119 list.
120 """
121 return [v for k, v in self._headers]
122
123 def items(self):
124 """Get all the header fields and values.
125
126 These will be sorted in the order they were in the original header
127 list, or were added to this instance, and may contain duplicates.
128 Any fields deleted and re-inserted are always appended to the header
129 list.
130 """
131 return self._headers[:]
132
133 def __repr__(self):
134 return "%s(%r)" % (self.__class__.__name__, self._headers)
135
136 def __str__(self):
137 """str() returns the formatted headers, complete with end line,
138 suitable for direct HTTP transmission."""
139 return '\r\n'.join(["%s: %s" % kv for kv in self._headers]+['',''])
140
141 def __bytes__(self):
142 return str(self).encode('iso-8859-1')
143
144 def setdefault(self,name,value):
145 """Return first matching header value for 'name', or 'value'
146
147 If there is no header named 'name', add a new header with name 'name'
148 and value 'value'."""
149 result = self.get(name)
150 if result is None:
151 self._headers.append((self._convert_string_type(name),
152 self._convert_string_type(value)))
153 return value
154 else:
155 return result
156
157 def add_header(self, _name, _value, **_params):
158 """Extended header setting.
159
160 _name is the header field to add. keyword arguments can be used to set
161 additional parameters for the header field, with underscores converted
162 to dashes. Normally the parameter will be added as key="value" unless
163 value is None, in which case only the key will be added.
164
165 Example:
166
167 h.add_header('content-disposition', 'attachment', filename='bud.gif')
168
169 Note that unlike the corresponding 'email.message' method, this does
170 *not* handle '(charset, language, value)' tuples: all values must be
171 strings or None.
172 """
173 parts = []
174 if _value is not None:
175 _value = self._convert_string_type(_value)
176 parts.append(_value)
177 for k, v in _params.items():
178 k = self._convert_string_type(k)
179 if v is None:
180 parts.append(k.replace('_', '-'))
181 else:
182 v = self._convert_string_type(v)
183 parts.append(_formatparam(k.replace('_', '-'), v))
184 self._headers.append((self._convert_string_type(_name), "; ".join(parts)))