summaryrefslogtreecommitdiffstats
path: root/Doc/lib/libcookie.tex
blob: bba9c79ed9335964ec3475dff6716eb9910df987 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
\section{\module{Cookie} ---
         HTTP state management}

\declaremodule{standard}{Cookie}
\modulesynopsis{Support for HTTP state management (cookies).}
\moduleauthor{Timothy O'Malley}{timo@alum.mit.edu}
\sectionauthor{Moshe Zadka}{moshez@zadka.site.co.il}


The \module{Cookie} module defines classes for abstracting the concept of 
cookies, an HTTP state management mechanism. It supports both simple
string-only cookies, and provides an abstraction for having any serializable
data-type as cookie value.

The module formerly strictly applied the parsing rules described in
the \rfc{2109} and \rfc{2068} specifications.  It has since been discovered
that MSIE 3.0x doesn't follow the character rules outlined in those
specs.  As a result, the parsing rules used are a bit less strict.

\begin{excdesc}{CookieError}
Exception failing because of \rfc{2109} invalidity: incorrect
attributes, incorrect \mailheader{Set-Cookie} header, etc.
\end{excdesc}

\begin{classdesc}{BaseCookie}{\optional{input}}
This class is a dictionary-like object whose keys are strings and
whose values are \class{Morsel} instances. Note that upon setting a key to
a value, the value is first converted to a \class{Morsel} containing
the key and the value.

If \var{input} is given, it is passed to the \method{load()} method.
\end{classdesc}

\begin{classdesc}{SimpleCookie}{\optional{input}}
This class derives from \class{BaseCookie} and overrides
\method{value_decode()} and \method{value_encode()} to be the identity
and \function{str()} respectively.
\end{classdesc}

\begin{classdesc}{SerialCookie}{\optional{input}}
This class derives from \class{BaseCookie} and overrides
\method{value_decode()} and \method{value_encode()} to be the
\function{pickle.loads()} and \function{pickle.dumps()}.

\deprecated{2.3}{Reading pickled values from untrusted
cookie data is a huge security hole, as pickle strings can be crafted
to cause arbitrary code to execute on your server.  It is supported
for backwards compatibility only, and may eventually go away.}
\end{classdesc}

\begin{classdesc}{SmartCookie}{\optional{input}}
This class derives from \class{BaseCookie}. It overrides
\method{value_decode()} to be \function{pickle.loads()} if it is a
valid pickle, and otherwise the value itself. It overrides
\method{value_encode()} to be \function{pickle.dumps()} unless it is a
string, in which case it returns the value itself.

\deprecated{2.3}{The same security warning from \class{SerialCookie}
applies here.}
\end{classdesc}

A further security note is warranted.  For backwards compatibility,
the \module{Cookie} module exports a class named \class{Cookie} which
is just an alias for \class{SmartCookie}.  This is probably a mistake
and will likely be removed in a future version.  You should not use
the \class{Cookie} class in your applications, for the same reason why
you should not use the \class{SerialCookie} class.


\begin{seealso}
  \seemodule{cookielib}{HTTP cookie handling for for web
    \emph{clients}.  The \module{cookielib} and \module{Cookie}
    modules do not depend on each other.}

  \seerfc{2109}{HTTP State Management Mechanism}{This is the state
                management specification implemented by this module.}
\end{seealso}


\subsection{Cookie Objects \label{cookie-objects}}

\begin{methoddesc}[BaseCookie]{value_decode}{val}
Return a decoded value from a string representation. Return value can
be any type. This method does nothing in \class{BaseCookie} --- it exists
so it can be overridden.
\end{methoddesc}

\begin{methoddesc}[BaseCookie]{value_encode}{val}
Return an encoded value. \var{val} can be any type, but return value
must be a string. This method does nothing in \class{BaseCookie} --- it exists
so it can be overridden

In general, it should be the case that \method{value_encode()} and 
\method{value_decode()} are inverses on the range of \var{value_decode}.
\end{methoddesc}

\begin{methoddesc}[BaseCookie]{output}{\optional{attrs\optional{, header\optional{, sep}}}}
Return a string representation suitable to be sent as HTTP headers.
\var{attrs} and \var{header} are sent to each \class{Morsel}'s
\method{output()} method. \var{sep} is used to join the headers
together, and is by default a newline.
\end{methoddesc}

\begin{methoddesc}[BaseCookie]{js_output}{\optional{attrs}}
Return an embeddable JavaScript snippet, which, if run on a browser which
supports JavaScript, will act the same as if the HTTP headers was sent.

The meaning for \var{attrs} is the same as in \method{output()}.
\end{methoddesc}

\begin{methoddesc}[BaseCookie]{load}{rawdata}
If \var{rawdata} is a string, parse it as an \code{HTTP_COOKIE} and add
the values found there as \class{Morsel}s. If it is a dictionary, it
is equivalent to:

\begin{verbatim}
for k, v in rawdata.items():
    cookie[k] = v
\end{verbatim}
\end{methoddesc}


\subsection{Morsel Objects \label{morsel-objects}}

\begin{classdesc}{Morsel}{}
Abstract a key/value pair, which has some \rfc{2109} attributes.

Morsels are dictionary-like objects, whose set of keys is constant ---
the valid \rfc{2109} attributes, which are

\begin{itemize}
\item \code{expires}
\item \code{path}
\item \code{comment}
\item \code{domain}
\item \code{max-age}
\item \code{secure}
\item \code{version}
\end{itemize}

The keys are case-insensitive.
\end{classdesc}

\begin{memberdesc}[Morsel]{value}
The value of the cookie.
\end{memberdesc}

\begin{memberdesc}[Morsel]{coded_value}
The encoded value of the cookie --- this is what should be sent.
\end{memberdesc}

\begin{memberdesc}[Morsel]{key}
The name of the cookie.
\end{memberdesc}

\begin{methoddesc}[Morsel]{set}{key, value, coded_value}
Set the \var{key}, \var{value} and \var{coded_value} members.
\end{methoddesc}

\begin{methoddesc}[Morsel]{isReservedKey}{K}
Whether \var{K} is a member of the set of keys of a \class{Morsel}.
\end{methoddesc}

\begin{methoddesc}[Morsel]{output}{\optional{attrs\optional{, header}}}
Return a string representation of the Morsel, suitable
to be sent as an HTTP header. By default, all the attributes are included,
unless \var{attrs} is given, in which case it should be a list of attributes
to use. \var{header} is by default \code{"Set-Cookie:"}.
\end{methoddesc}

\begin{methoddesc}[Morsel]{js_output}{\optional{attrs}}
Return an embeddable JavaScript snippet, which, if run on a browser which
supports JavaScript, will act the same as if the HTTP header was sent.

The meaning for \var{attrs} is the same as in \method{output()}.
\end{methoddesc}

\begin{methoddesc}[Morsel]{OutputString}{\optional{attrs}}
Return a string representing the Morsel, without any surrounding HTTP
or JavaScript.

The meaning for \var{attrs} is the same as in \method{output()}.
\end{methoddesc}
                

\subsection{Example \label{cookie-example}}

The following example demonstrates how to use the \module{Cookie} module.

\begin{verbatim}
>>> import Cookie
>>> C = Cookie.SimpleCookie()
>>> C = Cookie.SerialCookie()
>>> C = Cookie.SmartCookie()
>>> C["fig"] = "newton"
>>> C["sugar"] = "wafer"
>>> print C # generate HTTP headers
Set-Cookie: sugar=wafer;
Set-Cookie: fig=newton;
>>> print C.output() # same thing
Set-Cookie: sugar=wafer;
Set-Cookie: fig=newton;
>>> C = Cookie.SmartCookie()
>>> C["rocky"] = "road"
>>> C["rocky"]["path"] = "/cookie"
>>> print C.output(header="Cookie:")
Cookie: rocky=road; Path=/cookie;
>>> print C.output(attrs=[], header="Cookie:")
Cookie: rocky=road;
>>> C = Cookie.SmartCookie()
>>> C.load("chips=ahoy; vienna=finger") # load from a string (HTTP header)
>>> print C
Set-Cookie: vienna=finger;
Set-Cookie: chips=ahoy;
>>> C = Cookie.SmartCookie()
>>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')
>>> print C
Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;";
>>> C = Cookie.SmartCookie()
>>> C["oreo"] = "doublestuff"
>>> C["oreo"]["path"] = "/"
>>> print C
Set-Cookie: oreo=doublestuff; Path=/;
>>> C = Cookie.SmartCookie()
>>> C["twix"] = "none for you"
>>> C["twix"].value
'none for you'
>>> C = Cookie.SimpleCookie()
>>> C["number"] = 7 # equivalent to C["number"] = str(7)
>>> C["string"] = "seven"
>>> C["number"].value
'7'
>>> C["string"].value
'seven'
>>> print C
Set-Cookie: number=7;
Set-Cookie: string=seven;
>>> C = Cookie.SerialCookie()
>>> C["number"] = 7
>>> C["string"] = "seven"
>>> C["number"].value
7
>>> C["string"].value
'seven'
>>> print C
Set-Cookie: number="I7\012.";
Set-Cookie: string="S'seven'\012p1\012.";
>>> C = Cookie.SmartCookie()
>>> C["number"] = 7
>>> C["string"] = "seven"
>>> C["number"].value
7
>>> C["string"].value
'seven'
>>> print C
Set-Cookie: number="I7\012.";
Set-Cookie: string=seven;
\end{verbatim}