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