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@@ -0,0 +1,483 @@
+:mod:`urllib` --- Open arbitrary resources by URL
+=================================================
+
+.. module:: urllib
+ :synopsis: Open an arbitrary network resource by URL (requires sockets).
+
+.. note::
+ The :mod:`urllib` module has been split into parts and renamed in
+ Python 3.0 to :mod:`urllib.request`, :mod:`urllib.parse`,
+ and :mod:`urllib.error`. The :term:`2to3` tool will automatically adapt
+ imports when converting your sources to 3.0.
+ Also note that the :func:`urllib.urlopen` function has been removed in
+ Python 3.0 in favor of :func:`urllib2.urlopen`.
+
+.. index::
+ single: WWW
+ single: World Wide Web
+ single: URL
+
+This module provides a high-level interface for fetching data across the World
+Wide Web. In particular, the :func:`urlopen` function is similar to the
+built-in function :func:`open`, but accepts Universal Resource Locators (URLs)
+instead of filenames. Some restrictions apply --- it can only open URLs for
+reading, and no seek operations are available.
+
+High-level interface
+--------------------
+
+.. function:: urlopen(url[, data[, proxies]])
+
+ Open a network object denoted by a URL for reading. If the URL does not have a
+ scheme identifier, or if it has :file:`file:` as its scheme identifier, this
+ opens a local file (without universal newlines); otherwise it opens a socket to
+ a server somewhere on the network. If the connection cannot be made the
+ :exc:`IOError` exception is raised. If all went well, a file-like object is
+ returned. This supports the following methods: :meth:`read`, :meth:`readline`,
+ :meth:`readlines`, :meth:`fileno`, :meth:`close`, :meth:`info`, :meth:`getcode` and
+ :meth:`geturl`. It also has proper support for the :term:`iterator` protocol. One
+ caveat: the :meth:`read` method, if the size argument is omitted or negative,
+ may not read until the end of the data stream; there is no good way to determine
+ that the entire stream from a socket has been read in the general case.
+
+ Except for the :meth:`info`, :meth:`getcode` and :meth:`geturl` methods,
+ these methods have the same interface as for file objects --- see section
+ :ref:`bltin-file-objects` in this manual. (It is not a built-in file object,
+ however, so it can't be used at those few places where a true built-in file
+ object is required.)
+
+ .. index:: module: mimetools
+
+ The :meth:`info` method returns an instance of the class
+ :class:`mimetools.Message` containing meta-information associated with the
+ URL. When the method is HTTP, these headers are those returned by the server
+ at the head of the retrieved HTML page (including Content-Length and
+ Content-Type). When the method is FTP, a Content-Length header will be
+ present if (as is now usual) the server passed back a file length in response
+ to the FTP retrieval request. A Content-Type header will be present if the
+ MIME type can be guessed. When the method is local-file, returned headers
+ will include a Date representing the file's last-modified time, a
+ Content-Length giving file size, and a Content-Type containing a guess at the
+ file's type. See also the description of the :mod:`mimetools` module.
+
+ The :meth:`geturl` method returns the real URL of the page. In some cases, the
+ HTTP server redirects a client to another URL. The :func:`urlopen` function
+ handles this transparently, but in some cases the caller needs to know which URL
+ the client was redirected to. The :meth:`geturl` method can be used to get at
+ this redirected URL.
+
+ The :meth:`getcode` method returns the HTTP status code that was sent with the
+ response, or ``None`` if the URL is no HTTP URL.
+
+ If the *url* uses the :file:`http:` scheme identifier, the optional *data*
+ argument may be given to specify a ``POST`` request (normally the request type
+ is ``GET``). The *data* argument must be in standard
+ :mimetype:`application/x-www-form-urlencoded` format; see the :func:`urlencode`
+ function below.
+
+ The :func:`urlopen` function works transparently with proxies which do not
+ require authentication. In a Unix or Windows environment, set the
+ :envvar:`http_proxy`, or :envvar:`ftp_proxy` environment variables to a URL that
+ identifies the proxy server before starting the Python interpreter. For example
+ (the ``'%'`` is the command prompt)::
+
+ % http_proxy="http://www.someproxy.com:3128"
+ % export http_proxy
+ % python
+ ...
+
+ The :envvar:`no_proxy` environment variable can be used to specify hosts which
+ shouldn't be reached via proxy; if set, it should be a comma-separated list
+ of hostname suffixes, optionally with ``:port`` appended, for example
+ ``cern.ch,ncsa.uiuc.edu,some.host:8080``.
+
+ In a Windows environment, if no proxy environment variables are set, proxy
+ settings are obtained from the registry's Internet Settings section.
+
+ .. index:: single: Internet Config
+
+ In a Macintosh environment, :func:`urlopen` will retrieve proxy information from
+ Internet Config.
+
+ Alternatively, the optional *proxies* argument may be used to explicitly specify
+ proxies. It must be a dictionary mapping scheme names to proxy URLs, where an
+ empty dictionary causes no proxies to be used, and ``None`` (the default value)
+ causes environmental proxy settings to be used as discussed above. For
+ example::
+
+ # Use http://www.someproxy.com:3128 for http proxying
+ proxies = {'http': 'http://www.someproxy.com:3128'}
+ filehandle = urllib.urlopen(some_url, proxies=proxies)
+ # Don't use any proxies
+ filehandle = urllib.urlopen(some_url, proxies={})
+ # Use proxies from environment - both versions are equivalent
+ filehandle = urllib.urlopen(some_url, proxies=None)
+ filehandle = urllib.urlopen(some_url)
+
+ Proxies which require authentication for use are not currently supported; this
+ is considered an implementation limitation.
+
+ .. versionchanged:: 2.3
+ Added the *proxies* support.
+
+ .. versionchanged:: 2.6
+ Added :meth:`getcode` to returned object and support for the
+ :envvar:`no_proxy` environment variable.
+
+ .. deprecated:: 2.6
+ The :func:`urlopen` function has been removed in Python 3.0 in favor
+ of :func:`urllib2.urlopen`.
+
+
+.. function:: urlretrieve(url[, filename[, reporthook[, data]]])
+
+ Copy a network object denoted by a URL to a local file, if necessary. If the URL
+ points to a local file, or a valid cached copy of the object exists, the object
+ is not copied. Return a tuple ``(filename, headers)`` where *filename* is the
+ local file name under which the object can be found, and *headers* is whatever
+ the :meth:`info` method of the object returned by :func:`urlopen` returned (for
+ a remote object, possibly cached). Exceptions are the same as for
+ :func:`urlopen`.
+
+ The second argument, if present, specifies the file location to copy to (if
+ absent, the location will be a tempfile with a generated name). The third
+ argument, if present, is a hook function that will be called once on
+ establishment of the network connection and once after each block read
+ thereafter. The hook will be passed three arguments; a count of blocks
+ transferred so far, a block size in bytes, and the total size of the file. The
+ third argument may be ``-1`` on older FTP servers which do not return a file
+ size in response to a retrieval request.
+
+ If the *url* uses the :file:`http:` scheme identifier, the optional *data*
+ argument may be given to specify a ``POST`` request (normally the request type
+ is ``GET``). The *data* argument must in standard
+ :mimetype:`application/x-www-form-urlencoded` format; see the :func:`urlencode`
+ function below.
+
+ .. versionchanged:: 2.5
+ :func:`urlretrieve` will raise :exc:`ContentTooShortError` when it detects that
+ the amount of data available was less than the expected amount (which is the
+ size reported by a *Content-Length* header). This can occur, for example, when
+ the download is interrupted.
+
+ The *Content-Length* is treated as a lower bound: if there's more data to read,
+ urlretrieve reads more data, but if less data is available, it raises the
+ exception.
+
+ You can still retrieve the downloaded data in this case, it is stored in the
+ :attr:`content` attribute of the exception instance.
+
+ If no *Content-Length* header was supplied, urlretrieve can not check the size
+ of the data it has downloaded, and just returns it. In this case you just have
+ to assume that the download was successful.
+
+
+.. data:: _urlopener
+
+ The public functions :func:`urlopen` and :func:`urlretrieve` create an instance
+ of the :class:`FancyURLopener` class and use it to perform their requested
+ actions. To override this functionality, programmers can create a subclass of
+ :class:`URLopener` or :class:`FancyURLopener`, then assign an instance of that
+ class to the ``urllib._urlopener`` variable before calling the desired function.
+ For example, applications may want to specify a different
+ :mailheader:`User-Agent` header than :class:`URLopener` defines. This can be
+ accomplished with the following code::
+
+ import urllib
+
+ class AppURLopener(urllib.FancyURLopener):
+ version = "App/1.7"
+
+ urllib._urlopener = AppURLopener()
+
+
+.. function:: urlcleanup()
+
+ Clear the cache that may have been built up by previous calls to
+ :func:`urlretrieve`.
+
+
+Utility functions
+-----------------
+
+.. function:: quote(string[, safe])
+
+ Replace special characters in *string* using the ``%xx`` escape. Letters,
+ digits, and the characters ``'_.-'`` are never quoted. The optional *safe*
+ parameter specifies additional characters that should not be quoted --- its
+ default value is ``'/'``.
+
+ Example: ``quote('/~connolly/')`` yields ``'/%7econnolly/'``.
+
+
+.. function:: quote_plus(string[, safe])
+
+ Like :func:`quote`, but also replaces spaces by plus signs, as required for
+ quoting HTML form values. Plus signs in the original string are escaped unless
+ they are included in *safe*. It also does not have *safe* default to ``'/'``.
+
+
+.. function:: unquote(string)
+
+ Replace ``%xx`` escapes by their single-character equivalent.
+
+ Example: ``unquote('/%7Econnolly/')`` yields ``'/~connolly/'``.
+
+
+.. function:: unquote_plus(string)
+
+ Like :func:`unquote`, but also replaces plus signs by spaces, as required for
+ unquoting HTML form values.
+
+
+.. function:: urlencode(query[, doseq])
+
+ Convert a mapping object or a sequence of two-element tuples to a "url-encoded"
+ string, suitable to pass to :func:`urlopen` above as the optional *data*
+ argument. This is useful to pass a dictionary of form fields to a ``POST``
+ request. The resulting string is a series of ``key=value`` pairs separated by
+ ``'&'`` characters, where both *key* and *value* are quoted using
+ :func:`quote_plus` above. If the optional parameter *doseq* is present and
+ evaluates to true, individual ``key=value`` pairs are generated for each element
+ of the sequence. When a sequence of two-element tuples is used as the *query*
+ argument, the first element of each tuple is a key and the second is a value.
+ The order of parameters in the encoded string will match the order of parameter
+ tuples in the sequence. The :mod:`urlparse` module provides the functions
+ :func:`parse_qs` and :func:`parse_qsl` which are used to parse query strings
+ into Python data structures.
+
+
+.. function:: pathname2url(path)
+
+ Convert the pathname *path* from the local syntax for a path to the form used in
+ the path component of a URL. This does not produce a complete URL. The return
+ value will already be quoted using the :func:`quote` function.
+
+
+.. function:: url2pathname(path)
+
+ Convert the path component *path* from an encoded URL to the local syntax for a
+ path. This does not accept a complete URL. This function uses :func:`unquote`
+ to decode *path*.
+
+
+URL Opener objects
+------------------
+
+.. class:: URLopener([proxies[, **x509]])
+
+ Base class for opening and reading URLs. Unless you need to support opening
+ objects using schemes other than :file:`http:`, :file:`ftp:`, or :file:`file:`,
+ you probably want to use :class:`FancyURLopener`.
+
+ By default, the :class:`URLopener` class sends a :mailheader:`User-Agent` header
+ of ``urllib/VVV``, where *VVV* is the :mod:`urllib` version number.
+ Applications can define their own :mailheader:`User-Agent` header by subclassing
+ :class:`URLopener` or :class:`FancyURLopener` and setting the class attribute
+ :attr:`version` to an appropriate string value in the subclass definition.
+
+ The optional *proxies* parameter should be a dictionary mapping scheme names to
+ proxy URLs, where an empty dictionary turns proxies off completely. Its default
+ value is ``None``, in which case environmental proxy settings will be used if
+ present, as discussed in the definition of :func:`urlopen`, above.
+
+ Additional keyword parameters, collected in *x509*, may be used for
+ authentication of the client when using the :file:`https:` scheme. The keywords
+ *key_file* and *cert_file* are supported to provide an SSL key and certificate;
+ both are needed to support client authentication.
+
+ :class:`URLopener` objects will raise an :exc:`IOError` exception if the server
+ returns an error code.
+
+ .. method:: open(fullurl[, data])
+
+ Open *fullurl* using the appropriate protocol. This method sets up cache and
+ proxy information, then calls the appropriate open method with its input
+ arguments. If the scheme is not recognized, :meth:`open_unknown` is called.
+ The *data* argument has the same meaning as the *data* argument of
+ :func:`urlopen`.
+
+
+ .. method:: open_unknown(fullurl[, data])
+
+ Overridable interface to open unknown URL types.
+
+
+ .. method:: retrieve(url[, filename[, reporthook[, data]]])
+
+ Retrieves the contents of *url* and places it in *filename*. The return value
+ is a tuple consisting of a local filename and either a
+ :class:`mimetools.Message` object containing the response headers (for remote
+ URLs) or ``None`` (for local URLs). The caller must then open and read the
+ contents of *filename*. If *filename* is not given and the URL refers to a
+ local file, the input filename is returned. If the URL is non-local and
+ *filename* is not given, the filename is the output of :func:`tempfile.mktemp`
+ with a suffix that matches the suffix of the last path component of the input
+ URL. If *reporthook* is given, it must be a function accepting three numeric
+ parameters. It will be called after each chunk of data is read from the
+ network. *reporthook* is ignored for local URLs.
+
+ If the *url* uses the :file:`http:` scheme identifier, the optional *data*
+ argument may be given to specify a ``POST`` request (normally the request type
+ is ``GET``). The *data* argument must in standard
+ :mimetype:`application/x-www-form-urlencoded` format; see the :func:`urlencode`
+ function below.
+
+
+ .. attribute:: version
+
+ Variable that specifies the user agent of the opener object. To get
+ :mod:`urllib` to tell servers that it is a particular user agent, set this in a
+ subclass as a class variable or in the constructor before calling the base
+ constructor.
+
+
+.. class:: FancyURLopener(...)
+
+ :class:`FancyURLopener` subclasses :class:`URLopener` providing default handling
+ for the following HTTP response codes: 301, 302, 303, 307 and 401. For the 30x
+ response codes listed above, the :mailheader:`Location` header is used to fetch
+ the actual URL. For 401 response codes (authentication required), basic HTTP
+ authentication is performed. For the 30x response codes, recursion is bounded
+ by the value of the *maxtries* attribute, which defaults to 10.
+
+ For all other response codes, the method :meth:`http_error_default` is called
+ which you can override in subclasses to handle the error appropriately.
+
+ .. note::
+
+ According to the letter of :rfc:`2616`, 301 and 302 responses to POST requests
+ must not be automatically redirected without confirmation by the user. In
+ reality, browsers do allow automatic redirection of these responses, changing
+ the POST to a GET, and :mod:`urllib` reproduces this behaviour.
+
+ The parameters to the constructor are the same as those for :class:`URLopener`.
+
+ .. note::
+
+ When performing basic authentication, a :class:`FancyURLopener` instance calls
+ its :meth:`prompt_user_passwd` method. The default implementation asks the
+ users for the required information on the controlling terminal. A subclass may
+ override this method to support more appropriate behavior if needed.
+
+ The :class:`FancyURLopener` class offers one additional method that should be
+ overloaded to provide the appropriate behavior:
+
+ .. method:: prompt_user_passwd(host, realm)
+
+ Return information needed to authenticate the user at the given host in the
+ specified security realm. The return value should be a tuple, ``(user,
+ password)``, which can be used for basic authentication.
+
+ The implementation prompts for this information on the terminal; an application
+ should override this method to use an appropriate interaction model in the local
+ environment.
+
+.. exception:: ContentTooShortError(msg[, content])
+
+ This exception is raised when the :func:`urlretrieve` function detects that the
+ amount of the downloaded data is less than the expected amount (given by the
+ *Content-Length* header). The :attr:`content` attribute stores the downloaded
+ (and supposedly truncated) data.
+
+ .. versionadded:: 2.5
+
+
+:mod:`urllib` Restrictions
+--------------------------
+
+ .. index::
+ pair: HTTP; protocol
+ pair: FTP; protocol
+
+* Currently, only the following protocols are supported: HTTP, (versions 0.9 and
+ 1.0), FTP, and local files.
+
+* The caching feature of :func:`urlretrieve` has been disabled until I find the
+ time to hack proper processing of Expiration time headers.
+
+* There should be a function to query whether a particular URL is in the cache.
+
+* For backward compatibility, if a URL appears to point to a local file but the
+ file can't be opened, the URL is re-interpreted using the FTP protocol. This
+ can sometimes cause confusing error messages.
+
+* The :func:`urlopen` and :func:`urlretrieve` functions can cause arbitrarily
+ long delays while waiting for a network connection to be set up. This means
+ that it is difficult to build an interactive Web client using these functions
+ without using threads.
+
+ .. index::
+ single: HTML
+ pair: HTTP; protocol
+ module: htmllib
+
+* The data returned by :func:`urlopen` or :func:`urlretrieve` is the raw data
+ returned by the server. This may be binary data (such as an image), plain text
+ or (for example) HTML. The HTTP protocol provides type information in the reply
+ header, which can be inspected by looking at the :mailheader:`Content-Type`
+ header. If the returned data is HTML, you can use the module :mod:`htmllib` to
+ parse it.
+
+ .. index:: single: FTP
+
+* The code handling the FTP protocol cannot differentiate between a file and a
+ directory. This can lead to unexpected behavior when attempting to read a URL
+ that points to a file that is not accessible. If the URL ends in a ``/``, it is
+ assumed to refer to a directory and will be handled accordingly. But if an
+ attempt to read a file leads to a 550 error (meaning the URL cannot be found or
+ is not accessible, often for permission reasons), then the path is treated as a
+ directory in order to handle the case when a directory is specified by a URL but
+ the trailing ``/`` has been left off. This can cause misleading results when
+ you try to fetch a file whose read permissions make it inaccessible; the FTP
+ code will try to read it, fail with a 550 error, and then perform a directory
+ listing for the unreadable file. If fine-grained control is needed, consider
+ using the :mod:`ftplib` module, subclassing :class:`FancyURLOpener`, or changing
+ *_urlopener* to meet your needs.
+
+* This module does not support the use of proxies which require authentication.
+ This may be implemented in the future.
+
+ .. index:: module: urlparse
+
+* Although the :mod:`urllib` module contains (undocumented) routines to parse
+ and unparse URL strings, the recommended interface for URL manipulation is in
+ module :mod:`urlparse`.
+
+
+.. _urllib-examples:
+
+Examples
+--------
+
+Here is an example session that uses the ``GET`` method to retrieve a URL
+containing parameters::
+
+ >>> import urllib
+ >>> params = urllib.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
+ >>> f = urllib.urlopen("http://www.musi-cal.com/cgi-bin/query?%s" % params)
+ >>> print f.read()
+
+The following example uses the ``POST`` method instead::
+
+ >>> import urllib
+ >>> params = urllib.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
+ >>> f = urllib.urlopen("http://www.musi-cal.com/cgi-bin/query", params)
+ >>> print f.read()
+
+The following example uses an explicitly specified HTTP proxy, overriding
+environment settings::
+
+ >>> import urllib
+ >>> proxies = {'http': 'http://proxy.example.com:8080/'}
+ >>> opener = urllib.FancyURLopener(proxies)
+ >>> f = opener.open("http://www.python.org")
+ >>> f.read()
+
+The following example uses no proxies at all, overriding environment settings::
+
+ >>> import urllib
+ >>> opener = urllib.FancyURLopener({})
+ >>> f = opener.open("http://www.python.org/")
+ >>> f.read()
+