| :mod:`urllib.request` --- extensible library for opening URLs |
| ============================================================= |
| |
| .. module:: urllib.request |
| :synopsis: Next generation URL opening library. |
| .. moduleauthor:: Jeremy Hylton <jhylton@users.sourceforge.net> |
| .. sectionauthor:: Moshe Zadka <moshez@users.sourceforge.net> |
| |
| |
| The :mod:`urllib.request` module defines functions and classes which help in |
| opening URLs (mostly HTTP) in a complex world --- basic and digest |
| authentication, redirections, cookies and more. |
| |
| The :mod:`urllib.request` module defines the following functions: |
| |
| |
| .. function:: urlopen(url[, data][, timeout]) |
| |
| Open the URL *url*, which can be either a string or a :class:`Request` object. |
| |
| *data* may be a string specifying additional data to send to the server, or |
| ``None`` if no such data is needed. Currently HTTP requests are the only ones |
| that use *data*; the HTTP request will be a POST instead of a GET when the |
| *data* parameter is provided. *data* should be a buffer in the standard |
| :mimetype:`application/x-www-form-urlencoded` format. The |
| :func:`urllib.urlencode` function takes a mapping or sequence of 2-tuples and |
| returns a string in this format. |
| |
| The optional *timeout* parameter specifies a timeout in seconds for blocking |
| operations like the connection attempt (if not specified, the global default |
| timeout setting will be used). This actually only works for HTTP, HTTPS, |
| FTP and FTPS connections. |
| |
| This function returns a file-like object with two additional methods from |
| the :mod:`urllib.response` module |
| |
| * :meth:`geturl` --- return the URL of the resource retrieved, commonly used to |
| determine if a redirect was followed |
| |
| * :meth:`info` --- return the meta-information of the page, such as headers, in |
| the form of an ``http.client.HTTPMessage`` instance |
| (see `Quick Reference to HTTP Headers <http://www.cs.tut.fi/~jkorpela/http.html>`_) |
| |
| Raises :exc:`URLError` on errors. |
| |
| Note that ``None`` may be returned if no handler handles the request (though the |
| default installed global :class:`OpenerDirector` uses :class:`UnknownHandler` to |
| ensure this never happens). |
| The urlopen function from the previous version, Python 2.6 and earlier, of |
| the module urllib has been discontinued as urlopen can return the |
| file-object as the previous. The proxy handling, which in earlier was passed |
| as a dict parameter to urlopen can be availed by the use of `ProxyHandler` |
| objects. |
| |
| |
| .. function:: install_opener(opener) |
| |
| Install an :class:`OpenerDirector` instance as the default global opener. |
| Installing an opener is only necessary if you want urlopen to use that opener; |
| otherwise, simply call :meth:`OpenerDirector.open` instead of :func:`urlopen`. |
| The code does not check for a real :class:`OpenerDirector`, and any class with |
| the appropriate interface will work. |
| |
| |
| .. function:: build_opener([handler, ...]) |
| |
| Return an :class:`OpenerDirector` instance, which chains the handlers in the |
| order given. *handler*\s can be either instances of :class:`BaseHandler`, or |
| subclasses of :class:`BaseHandler` (in which case it must be possible to call |
| the constructor without any parameters). Instances of the following classes |
| will be in front of the *handler*\s, unless the *handler*\s contain them, |
| instances of them or subclasses of them: :class:`ProxyHandler`, |
| :class:`UnknownHandler`, :class:`HTTPHandler`, :class:`HTTPDefaultErrorHandler`, |
| :class:`HTTPRedirectHandler`, :class:`FTPHandler`, :class:`FileHandler`, |
| :class:`HTTPErrorProcessor`. |
| |
| If the Python installation has SSL support (i.e., if the :mod:`ssl` module can be imported), |
| :class:`HTTPSHandler` will also be added. |
| |
| A :class:`BaseHandler` subclass may also change its :attr:`handler_order` |
| member variable to modify its position in the handlers list. |
| |
| .. 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. |
| |
| :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.request |
| |
| class AppURLopener(urllib.request.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`. |
| |
| .. 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*. |
| |
| The following classes are provided: |
| |
| .. class:: Request(url[, data][, headers][, origin_req_host][, unverifiable]) |
| |
| This class is an abstraction of a URL request. |
| |
| *url* should be a string containing a valid URL. |
| |
| *data* may be a string specifying additional data to send to the server, or |
| ``None`` if no such data is needed. Currently HTTP requests are the only ones |
| that use *data*; the HTTP request will be a POST instead of a GET when the |
| *data* parameter is provided. *data* should be a buffer in the standard |
| :mimetype:`application/x-www-form-urlencoded` format. The |
| :func:`urllib.urlencode` function takes a mapping or sequence of 2-tuples and |
| returns a string in this format. |
| |
| *headers* should be a dictionary, and will be treated as if :meth:`add_header` |
| was called with each key and value as arguments. This is often used to "spoof" |
| the ``User-Agent`` header, which is used by a browser to identify itself -- |
| some HTTP servers only allow requests coming from common browsers as opposed |
| to scripts. For example, Mozilla Firefox may identify itself as ``"Mozilla/5.0 |
| (X11; U; Linux i686) Gecko/20071127 Firefox/2.0.0.11"``, while :mod:`urllib`'s |
| default user agent string is ``"Python-urllib/2.6"`` (on Python 2.6). |
| |
| The final two arguments are only of interest for correct handling of third-party |
| HTTP cookies: |
| |
| *origin_req_host* should be the request-host of the origin transaction, as |
| defined by :rfc:`2965`. It defaults to ``http.cookiejar.request_host(self)``. |
| This is the host name or IP address of the original request that was |
| initiated by the user. For example, if the request is for an image in an |
| HTML document, this should be the request-host of the request for the page |
| containing the image. |
| |
| *unverifiable* should indicate whether the request is unverifiable, as defined |
| by RFC 2965. It defaults to False. An unverifiable request is one whose URL |
| the user did not have the option to approve. For example, if the request is for |
| an image in an HTML document, and the user had no option to approve the |
| automatic fetching of the image, this should be true. |
| |
| .. 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:`email.message.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. |
| |
| .. class:: OpenerDirector() |
| |
| The :class:`OpenerDirector` class opens URLs via :class:`BaseHandler`\ s chained |
| together. It manages the chaining of handlers, and recovery from errors. |
| |
| |
| .. class:: BaseHandler() |
| |
| This is the base class for all registered handlers --- and handles only the |
| simple mechanics of registration. |
| |
| |
| .. class:: HTTPDefaultErrorHandler() |
| |
| A class which defines a default handler for HTTP error responses; all responses |
| are turned into :exc:`HTTPError` exceptions. |
| |
| |
| .. class:: HTTPRedirectHandler() |
| |
| A class to handle redirections. |
| |
| |
| .. class:: HTTPCookieProcessor([cookiejar]) |
| |
| A class to handle HTTP Cookies. |
| |
| |
| .. class:: ProxyHandler([proxies]) |
| |
| Cause requests to go through a proxy. If *proxies* is given, it must be a |
| dictionary mapping protocol names to URLs of proxies. The default is to read the |
| list of proxies from the environment variables :envvar:`<protocol>_proxy`. |
| To disable autodetected proxy pass an empty dictionary. |
| |
| |
| .. class:: HTTPPasswordMgr() |
| |
| Keep a database of ``(realm, uri) -> (user, password)`` mappings. |
| |
| |
| .. class:: HTTPPasswordMgrWithDefaultRealm() |
| |
| Keep a database of ``(realm, uri) -> (user, password)`` mappings. A realm of |
| ``None`` is considered a catch-all realm, which is searched if no other realm |
| fits. |
| |
| |
| .. class:: AbstractBasicAuthHandler([password_mgr]) |
| |
| This is a mixin class that helps with HTTP authentication, both to the remote |
| host and to a proxy. *password_mgr*, if given, should be something that is |
| compatible with :class:`HTTPPasswordMgr`; refer to section |
| :ref:`http-password-mgr` for information on the interface that must be |
| supported. |
| |
| |
| .. class:: HTTPBasicAuthHandler([password_mgr]) |
| |
| Handle authentication with the remote host. *password_mgr*, if given, should be |
| something that is compatible with :class:`HTTPPasswordMgr`; refer to section |
| :ref:`http-password-mgr` for information on the interface that must be |
| supported. |
| |
| |
| .. class:: ProxyBasicAuthHandler([password_mgr]) |
| |
| Handle authentication with the proxy. *password_mgr*, if given, should be |
| something that is compatible with :class:`HTTPPasswordMgr`; refer to section |
| :ref:`http-password-mgr` for information on the interface that must be |
| supported. |
| |
| |
| .. class:: AbstractDigestAuthHandler([password_mgr]) |
| |
| This is a mixin class that helps with HTTP authentication, both to the remote |
| host and to a proxy. *password_mgr*, if given, should be something that is |
| compatible with :class:`HTTPPasswordMgr`; refer to section |
| :ref:`http-password-mgr` for information on the interface that must be |
| supported. |
| |
| |
| .. class:: HTTPDigestAuthHandler([password_mgr]) |
| |
| Handle authentication with the remote host. *password_mgr*, if given, should be |
| something that is compatible with :class:`HTTPPasswordMgr`; refer to section |
| :ref:`http-password-mgr` for information on the interface that must be |
| supported. |
| |
| |
| .. class:: ProxyDigestAuthHandler([password_mgr]) |
| |
| Handle authentication with the proxy. *password_mgr*, if given, should be |
| something that is compatible with :class:`HTTPPasswordMgr`; refer to section |
| :ref:`http-password-mgr` for information on the interface that must be |
| supported. |
| |
| |
| .. class:: HTTPHandler() |
| |
| A class to handle opening of HTTP URLs. |
| |
| |
| .. class:: HTTPSHandler() |
| |
| A class to handle opening of HTTPS URLs. |
| |
| |
| .. class:: FileHandler() |
| |
| Open local files. |
| |
| |
| .. class:: FTPHandler() |
| |
| Open FTP URLs. |
| |
| |
| .. class:: CacheFTPHandler() |
| |
| Open FTP URLs, keeping a cache of open FTP connections to minimize delays. |
| |
| |
| .. class:: UnknownHandler() |
| |
| A catch-all class to handle unknown URLs. |
| |
| |
| .. _request-objects: |
| |
| Request Objects |
| --------------- |
| |
| The following methods describe all of :class:`Request`'s public interface, and |
| so all must be overridden in subclasses. |
| |
| |
| .. method:: Request.add_data(data) |
| |
| Set the :class:`Request` data to *data*. This is ignored by all handlers except |
| HTTP handlers --- and there it should be a byte string, and will change the |
| request to be ``POST`` rather than ``GET``. |
| |
| |
| .. method:: Request.get_method() |
| |
| Return a string indicating the HTTP request method. This is only meaningful for |
| HTTP requests, and currently always returns ``'GET'`` or ``'POST'``. |
| |
| |
| .. method:: Request.has_data() |
| |
| Return whether the instance has a non-\ ``None`` data. |
| |
| |
| .. method:: Request.get_data() |
| |
| Return the instance's data. |
| |
| |
| .. method:: Request.add_header(key, val) |
| |
| Add another header to the request. Headers are currently ignored by all |
| handlers except HTTP handlers, where they are added to the list of headers sent |
| to the server. Note that there cannot be more than one header with the same |
| name, and later calls will overwrite previous calls in case the *key* collides. |
| Currently, this is no loss of HTTP functionality, since all headers which have |
| meaning when used more than once have a (header-specific) way of gaining the |
| same functionality using only one header. |
| |
| |
| .. method:: Request.add_unredirected_header(key, header) |
| |
| Add a header that will not be added to a redirected request. |
| |
| |
| .. method:: Request.has_header(header) |
| |
| Return whether the instance has the named header (checks both regular and |
| unredirected). |
| |
| |
| .. method:: Request.get_full_url() |
| |
| Return the URL given in the constructor. |
| |
| |
| .. method:: Request.get_type() |
| |
| Return the type of the URL --- also known as the scheme. |
| |
| |
| .. method:: Request.get_host() |
| |
| Return the host to which a connection will be made. |
| |
| |
| .. method:: Request.get_selector() |
| |
| Return the selector --- the part of the URL that is sent to the server. |
| |
| |
| .. method:: Request.set_proxy(host, type) |
| |
| Prepare the request by connecting to a proxy server. The *host* and *type* will |
| replace those of the instance, and the instance's selector will be the original |
| URL given in the constructor. |
| |
| |
| .. method:: Request.get_origin_req_host() |
| |
| Return the request-host of the origin transaction, as defined by :rfc:`2965`. |
| See the documentation for the :class:`Request` constructor. |
| |
| |
| .. method:: Request.is_unverifiable() |
| |
| Return whether the request is unverifiable, as defined by RFC 2965. See the |
| documentation for the :class:`Request` constructor. |
| |
| |
| .. _opener-director-objects: |
| |
| OpenerDirector Objects |
| ---------------------- |
| |
| :class:`OpenerDirector` instances have the following methods: |
| |
| |
| .. method:: OpenerDirector.add_handler(handler) |
| |
| *handler* should be an instance of :class:`BaseHandler`. The following methods |
| are searched, and added to the possible chains (note that HTTP errors are a |
| special case). |
| |
| * :meth:`protocol_open` --- signal that the handler knows how to open *protocol* |
| URLs. |
| |
| * :meth:`http_error_type` --- signal that the handler knows how to handle HTTP |
| errors with HTTP error code *type*. |
| |
| * :meth:`protocol_error` --- signal that the handler knows how to handle errors |
| from (non-\ ``http``) *protocol*. |
| |
| * :meth:`protocol_request` --- signal that the handler knows how to pre-process |
| *protocol* requests. |
| |
| * :meth:`protocol_response` --- signal that the handler knows how to |
| post-process *protocol* responses. |
| |
| |
| .. method:: OpenerDirector.open(url[, data][, timeout]) |
| |
| Open the given *url* (which can be a request object or a string), optionally |
| passing the given *data*. Arguments, return values and exceptions raised are |
| the same as those of :func:`urlopen` (which simply calls the :meth:`open` |
| method on the currently installed global :class:`OpenerDirector`). The |
| optional *timeout* parameter specifies a timeout in seconds for blocking |
| operations like the connection attempt (if not specified, the global default |
| timeout setting will be usedi). The timeout feature actually works only for |
| HTTP, HTTPS, FTP and FTPS connections). |
| |
| |
| .. method:: OpenerDirector.error(proto[, arg[, ...]]) |
| |
| Handle an error of the given protocol. This will call the registered error |
| handlers for the given protocol with the given arguments (which are protocol |
| specific). The HTTP protocol is a special case which uses the HTTP response |
| code to determine the specific error handler; refer to the :meth:`http_error_\*` |
| methods of the handler classes. |
| |
| Return values and exceptions raised are the same as those of :func:`urlopen`. |
| |
| OpenerDirector objects open URLs in three stages: |
| |
| The order in which these methods are called within each stage is determined by |
| sorting the handler instances. |
| |
| #. Every handler with a method named like :meth:`protocol_request` has that |
| method called to pre-process the request. |
| |
| #. Handlers with a method named like :meth:`protocol_open` are called to handle |
| the request. This stage ends when a handler either returns a non-\ :const:`None` |
| value (ie. a response), or raises an exception (usually :exc:`URLError`). |
| Exceptions are allowed to propagate. |
| |
| In fact, the above algorithm is first tried for methods named |
| :meth:`default_open`. If all such methods return :const:`None`, the algorithm |
| is repeated for methods named like :meth:`protocol_open`. If all such methods |
| return :const:`None`, the algorithm is repeated for methods named |
| :meth:`unknown_open`. |
| |
| Note that the implementation of these methods may involve calls of the parent |
| :class:`OpenerDirector` instance's :meth:`.open` and :meth:`.error` methods. |
| |
| #. Every handler with a method named like :meth:`protocol_response` has that |
| method called to post-process the response. |
| |
| |
| .. _base-handler-objects: |
| |
| BaseHandler Objects |
| ------------------- |
| |
| :class:`BaseHandler` objects provide a couple of methods that are directly |
| useful, and others that are meant to be used by derived classes. These are |
| intended for direct use: |
| |
| |
| .. method:: BaseHandler.add_parent(director) |
| |
| Add a director as parent. |
| |
| |
| .. method:: BaseHandler.close() |
| |
| Remove any parents. |
| |
| The following members and methods should only be used by classes derived from |
| :class:`BaseHandler`. |
| |
| .. note:: |
| |
| The convention has been adopted that subclasses defining |
| :meth:`protocol_request` or :meth:`protocol_response` methods are named |
| :class:`\*Processor`; all others are named :class:`\*Handler`. |
| |
| |
| .. attribute:: BaseHandler.parent |
| |
| A valid :class:`OpenerDirector`, which can be used to open using a different |
| protocol, or handle errors. |
| |
| |
| .. method:: BaseHandler.default_open(req) |
| |
| This method is *not* defined in :class:`BaseHandler`, but subclasses should |
| define it if they want to catch all URLs. |
| |
| This method, if implemented, will be called by the parent |
| :class:`OpenerDirector`. It should return a file-like object as described in |
| the return value of the :meth:`open` of :class:`OpenerDirector`, or ``None``. |
| It should raise :exc:`URLError`, unless a truly exceptional thing happens (for |
| example, :exc:`MemoryError` should not be mapped to :exc:`URLError`). |
| |
| This method will be called before any protocol-specific open method. |
| |
| |
| .. method:: BaseHandler.protocol_open(req) |
| :noindex: |
| |
| This method is *not* defined in :class:`BaseHandler`, but subclasses should |
| define it if they want to handle URLs with the given protocol. |
| |
| This method, if defined, will be called by the parent :class:`OpenerDirector`. |
| Return values should be the same as for :meth:`default_open`. |
| |
| |
| .. method:: BaseHandler.unknown_open(req) |
| |
| This method is *not* defined in :class:`BaseHandler`, but subclasses should |
| define it if they want to catch all URLs with no specific registered handler to |
| open it. |
| |
| This method, if implemented, will be called by the :attr:`parent` |
| :class:`OpenerDirector`. Return values should be the same as for |
| :meth:`default_open`. |
| |
| |
| .. method:: BaseHandler.http_error_default(req, fp, code, msg, hdrs) |
| |
| This method is *not* defined in :class:`BaseHandler`, but subclasses should |
| override it if they intend to provide a catch-all for otherwise unhandled HTTP |
| errors. It will be called automatically by the :class:`OpenerDirector` getting |
| the error, and should not normally be called in other circumstances. |
| |
| *req* will be a :class:`Request` object, *fp* will be a file-like object with |
| the HTTP error body, *code* will be the three-digit code of the error, *msg* |
| will be the user-visible explanation of the code and *hdrs* will be a mapping |
| object with the headers of the error. |
| |
| Return values and exceptions raised should be the same as those of |
| :func:`urlopen`. |
| |
| |
| .. method:: BaseHandler.http_error_nnn(req, fp, code, msg, hdrs) |
| |
| *nnn* should be a three-digit HTTP error code. This method is also not defined |
| in :class:`BaseHandler`, but will be called, if it exists, on an instance of a |
| subclass, when an HTTP error with code *nnn* occurs. |
| |
| Subclasses should override this method to handle specific HTTP errors. |
| |
| Arguments, return values and exceptions raised should be the same as for |
| :meth:`http_error_default`. |
| |
| |
| .. method:: BaseHandler.protocol_request(req) |
| :noindex: |
| |
| This method is *not* defined in :class:`BaseHandler`, but subclasses should |
| define it if they want to pre-process requests of the given protocol. |
| |
| This method, if defined, will be called by the parent :class:`OpenerDirector`. |
| *req* will be a :class:`Request` object. The return value should be a |
| :class:`Request` object. |
| |
| |
| .. method:: BaseHandler.protocol_response(req, response) |
| :noindex: |
| |
| This method is *not* defined in :class:`BaseHandler`, but subclasses should |
| define it if they want to post-process responses of the given protocol. |
| |
| This method, if defined, will be called by the parent :class:`OpenerDirector`. |
| *req* will be a :class:`Request` object. *response* will be an object |
| implementing the same interface as the return value of :func:`urlopen`. The |
| return value should implement the same interface as the return value of |
| :func:`urlopen`. |
| |
| |
| .. _http-redirect-handler: |
| |
| HTTPRedirectHandler Objects |
| --------------------------- |
| |
| .. note:: |
| |
| Some HTTP redirections require action from this module's client code. If this |
| is the case, :exc:`HTTPError` is raised. See :rfc:`2616` for details of the |
| precise meanings of the various redirection codes. |
| |
| |
| .. method:: HTTPRedirectHandler.redirect_request(req, fp, code, msg, hdrs) |
| |
| Return a :class:`Request` or ``None`` in response to a redirect. This is called |
| by the default implementations of the :meth:`http_error_30\*` methods when a |
| redirection is received from the server. If a redirection should take place, |
| return a new :class:`Request` to allow :meth:`http_error_30\*` to perform the |
| redirect. Otherwise, raise :exc:`HTTPError` if no other handler should try to |
| handle this URL, or return ``None`` if you can't but another handler might. |
| |
| .. note:: |
| |
| The default implementation of this method does not strictly follow :rfc:`2616`, |
| which says that 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 the default implementation reproduces this behavior. |
| |
| |
| .. method:: HTTPRedirectHandler.http_error_301(req, fp, code, msg, hdrs) |
| |
| Redirect to the ``Location:`` URL. This method is called by the parent |
| :class:`OpenerDirector` when getting an HTTP 'moved permanently' response. |
| |
| |
| .. method:: HTTPRedirectHandler.http_error_302(req, fp, code, msg, hdrs) |
| |
| The same as :meth:`http_error_301`, but called for the 'found' response. |
| |
| |
| .. method:: HTTPRedirectHandler.http_error_303(req, fp, code, msg, hdrs) |
| |
| The same as :meth:`http_error_301`, but called for the 'see other' response. |
| |
| |
| .. method:: HTTPRedirectHandler.http_error_307(req, fp, code, msg, hdrs) |
| |
| The same as :meth:`http_error_301`, but called for the 'temporary redirect' |
| response. |
| |
| |
| .. _http-cookie-processor: |
| |
| HTTPCookieProcessor Objects |
| --------------------------- |
| |
| :class:`HTTPCookieProcessor` instances have one attribute: |
| |
| .. attribute:: HTTPCookieProcessor.cookiejar |
| |
| The :class:`http.cookiejar.CookieJar` in which cookies are stored. |
| |
| |
| .. _proxy-handler: |
| |
| ProxyHandler Objects |
| -------------------- |
| |
| |
| .. method:: ProxyHandler.protocol_open(request) |
| :noindex: |
| |
| The :class:`ProxyHandler` will have a method :meth:`protocol_open` for every |
| *protocol* which has a proxy in the *proxies* dictionary given in the |
| constructor. The method will modify requests to go through the proxy, by |
| calling ``request.set_proxy()``, and call the next handler in the chain to |
| actually execute the protocol. |
| |
| |
| .. _http-password-mgr: |
| |
| HTTPPasswordMgr Objects |
| ----------------------- |
| |
| These methods are available on :class:`HTTPPasswordMgr` and |
| :class:`HTTPPasswordMgrWithDefaultRealm` objects. |
| |
| |
| .. method:: HTTPPasswordMgr.add_password(realm, uri, user, passwd) |
| |
| *uri* can be either a single URI, or a sequence of URIs. *realm*, *user* and |
| *passwd* must be strings. This causes ``(user, passwd)`` to be used as |
| authentication tokens when authentication for *realm* and a super-URI of any of |
| the given URIs is given. |
| |
| |
| .. method:: HTTPPasswordMgr.find_user_password(realm, authuri) |
| |
| Get user/password for given realm and URI, if any. This method will return |
| ``(None, None)`` if there is no matching user/password. |
| |
| For :class:`HTTPPasswordMgrWithDefaultRealm` objects, the realm ``None`` will be |
| searched if the given *realm* has no matching user/password. |
| |
| |
| .. _abstract-basic-auth-handler: |
| |
| AbstractBasicAuthHandler Objects |
| -------------------------------- |
| |
| |
| .. method:: AbstractBasicAuthHandler.http_error_auth_reqed(authreq, host, req, headers) |
| |
| Handle an authentication request by getting a user/password pair, and re-trying |
| the request. *authreq* should be the name of the header where the information |
| about the realm is included in the request, *host* specifies the URL and path to |
| authenticate for, *req* should be the (failed) :class:`Request` object, and |
| *headers* should be the error headers. |
| |
| *host* is either an authority (e.g. ``"python.org"``) or a URL containing an |
| authority component (e.g. ``"http://python.org/"``). In either case, the |
| authority must not contain a userinfo component (so, ``"python.org"`` and |
| ``"python.org:80"`` are fine, ``"joe:password@python.org"`` is not). |
| |
| |
| .. _http-basic-auth-handler: |
| |
| HTTPBasicAuthHandler Objects |
| ---------------------------- |
| |
| |
| .. method:: HTTPBasicAuthHandler.http_error_401(req, fp, code, msg, hdrs) |
| |
| Retry the request with authentication information, if available. |
| |
| |
| .. _proxy-basic-auth-handler: |
| |
| ProxyBasicAuthHandler Objects |
| ----------------------------- |
| |
| |
| .. method:: ProxyBasicAuthHandler.http_error_407(req, fp, code, msg, hdrs) |
| |
| Retry the request with authentication information, if available. |
| |
| |
| .. _abstract-digest-auth-handler: |
| |
| AbstractDigestAuthHandler Objects |
| --------------------------------- |
| |
| |
| .. method:: AbstractDigestAuthHandler.http_error_auth_reqed(authreq, host, req, headers) |
| |
| *authreq* should be the name of the header where the information about the realm |
| is included in the request, *host* should be the host to authenticate to, *req* |
| should be the (failed) :class:`Request` object, and *headers* should be the |
| error headers. |
| |
| |
| .. _http-digest-auth-handler: |
| |
| HTTPDigestAuthHandler Objects |
| ----------------------------- |
| |
| |
| .. method:: HTTPDigestAuthHandler.http_error_401(req, fp, code, msg, hdrs) |
| |
| Retry the request with authentication information, if available. |
| |
| |
| .. _proxy-digest-auth-handler: |
| |
| ProxyDigestAuthHandler Objects |
| ------------------------------ |
| |
| |
| .. method:: ProxyDigestAuthHandler.http_error_407(req, fp, code, msg, hdrs) |
| |
| Retry the request with authentication information, if available. |
| |
| |
| .. _http-handler-objects: |
| |
| HTTPHandler Objects |
| ------------------- |
| |
| |
| .. method:: HTTPHandler.http_open(req) |
| |
| Send an HTTP request, which can be either GET or POST, depending on |
| ``req.has_data()``. |
| |
| |
| .. _https-handler-objects: |
| |
| HTTPSHandler Objects |
| -------------------- |
| |
| |
| .. method:: HTTPSHandler.https_open(req) |
| |
| Send an HTTPS request, which can be either GET or POST, depending on |
| ``req.has_data()``. |
| |
| |
| .. _file-handler-objects: |
| |
| FileHandler Objects |
| ------------------- |
| |
| |
| .. method:: FileHandler.file_open(req) |
| |
| Open the file locally, if there is no host name, or the host name is |
| ``'localhost'``. Change the protocol to ``ftp`` otherwise, and retry opening it |
| using :attr:`parent`. |
| |
| |
| .. _ftp-handler-objects: |
| |
| FTPHandler Objects |
| ------------------ |
| |
| |
| .. method:: FTPHandler.ftp_open(req) |
| |
| Open the FTP file indicated by *req*. The login is always done with empty |
| username and password. |
| |
| |
| .. _cacheftp-handler-objects: |
| |
| CacheFTPHandler Objects |
| ----------------------- |
| |
| :class:`CacheFTPHandler` objects are :class:`FTPHandler` objects with the |
| following additional methods: |
| |
| |
| .. method:: CacheFTPHandler.setTimeout(t) |
| |
| Set timeout of connections to *t* seconds. |
| |
| |
| .. method:: CacheFTPHandler.setMaxConns(m) |
| |
| Set maximum number of cached connections to *m*. |
| |
| |
| .. _unknown-handler-objects: |
| |
| UnknownHandler Objects |
| ---------------------- |
| |
| |
| .. method:: UnknownHandler.unknown_open() |
| |
| Raise a :exc:`URLError` exception. |
| |
| |
| .. _http-error-processor-objects: |
| |
| HTTPErrorProcessor Objects |
| -------------------------- |
| |
| .. method:: HTTPErrorProcessor.unknown_open() |
| |
| Process HTTP error responses. |
| |
| For 200 error codes, the response object is returned immediately. |
| |
| For non-200 error codes, this simply passes the job on to the |
| :meth:`protocol_error_code` handler methods, via :meth:`OpenerDirector.error`. |
| Eventually, :class:`HTTPDefaultErrorHandler` will raise an |
| :exc:`HTTPError` if no other handler handles the error. |
| |
| |
| .. _urllib-request-examples: |
| |
| Examples |
| -------- |
| |
| This example gets the python.org main page and displays the first 100 bytes of |
| it:: |
| |
| >>> import urllib.request |
| >>> f = urllib.request.urlopen('http://www.python.org/') |
| >>> print(f.read(100)) |
| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
| <?xml-stylesheet href="./css/ht2html |
| |
| Here we are sending a data-stream to the stdin of a CGI and reading the data it |
| returns to us. Note that this example will only work when the Python |
| installation supports SSL. :: |
| |
| >>> import urllib.request |
| >>> req = urllib.request.Request(url='https://localhost/cgi-bin/test.cgi', |
| ... data='This data is passed to stdin of the CGI') |
| >>> f = urllib.request.urlopen(req) |
| >>> print(f.read()) |
| Got Data: "This data is passed to stdin of the CGI" |
| |
| The code for the sample CGI used in the above example is:: |
| |
| #!/usr/bin/env python |
| import sys |
| data = sys.stdin.read() |
| print('Content-type: text-plain\n\nGot Data: "%s"' % data) |
| |
| Use of Basic HTTP Authentication:: |
| |
| import urllib.request |
| # Create an OpenerDirector with support for Basic HTTP Authentication... |
| auth_handler = urllib.request.HTTPBasicAuthHandler() |
| auth_handler.add_password(realm='PDQ Application', |
| uri='https://mahler:8092/site-updates.py', |
| user='klem', |
| passwd='kadidd!ehopper') |
| opener = urllib.request.build_opener(auth_handler) |
| # ...and install it globally so it can be used with urlopen. |
| urllib.request.install_opener(opener) |
| urllib.request.urlopen('http://www.example.com/login.html') |
| |
| :func:`build_opener` provides many handlers by default, including a |
| :class:`ProxyHandler`. By default, :class:`ProxyHandler` uses the environment |
| variables named ``<scheme>_proxy``, where ``<scheme>`` is the URL scheme |
| involved. For example, the :envvar:`http_proxy` environment variable is read to |
| obtain the HTTP proxy's URL. |
| |
| This example replaces the default :class:`ProxyHandler` with one that uses |
| programatically-supplied proxy URLs, and adds proxy authorization support with |
| :class:`ProxyBasicAuthHandler`. :: |
| |
| proxy_handler = urllib.request.ProxyHandler({'http': 'http://www.example.com:3128/'}) |
| proxy_auth_handler = urllib.request.HTTPBasicAuthHandler() |
| proxy_auth_handler.add_password('realm', 'host', 'username', 'password') |
| |
| opener = build_opener(proxy_handler, proxy_auth_handler) |
| # This time, rather than install the OpenerDirector, we use it directly: |
| opener.open('http://www.example.com/login.html') |
| |
| Adding HTTP headers: |
| |
| Use the *headers* argument to the :class:`Request` constructor, or:: |
| |
| import urllib.request |
| req = urllib.request.Request('http://www.example.com/') |
| req.add_header('Referer', 'http://www.python.org/') |
| r = urllib.request.urlopen(req) |
| |
| :class:`OpenerDirector` automatically adds a :mailheader:`User-Agent` header to |
| every :class:`Request`. To change this:: |
| |
| import urllib.request |
| opener = urllib.request.build_opener() |
| opener.addheaders = [('User-agent', 'Mozilla/5.0')] |
| opener.open('http://www.example.com/') |
| |
| Also, remember that a few standard headers (:mailheader:`Content-Length`, |
| :mailheader:`Content-Type` and :mailheader:`Host`) are added when the |
| :class:`Request` is passed to :func:`urlopen` (or :meth:`OpenerDirector.open`). |
| |
| .. _urllib-examples: |
| |
| Here is an example session that uses the ``GET`` method to retrieve a URL |
| containing parameters:: |
| |
| >>> import urllib.request |
| >>> import urllib.parse |
| >>> params = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0}) |
| >>> f = urllib.request.urlopen("http://www.musi-cal.com/cgi-bin/query?%s" % params) |
| >>> print(f.read()) |
| |
| The following example uses the ``POST`` method instead:: |
| |
| >>> import urllib.request |
| >>> import urllib.parse |
| >>> params = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0}) |
| >>> f = urllib.request.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.request |
| >>> proxies = {'http': 'http://proxy.example.com:8080/'} |
| >>> opener = urllib.request.FancyURLopener(proxies) |
| >>> f = opener.open("http://www.python.org") |
| >>> f.read() |
| |
| The following example uses no proxies at all, overriding environment settings:: |
| |
| >>> import urllib.request |
| >>> opener = urllib.request.FancyURLopener({}) |
| >>> f = opener.open("http://www.python.org/") |
| >>> f.read() |
| |
| |
| :mod:`urllib.request` 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 |
| |
| * 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:`html.parser` 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. |
| |
| |
| |
| :mod:`urllib.response` --- Response classes used by urllib. |
| =========================================================== |
| |
| .. module:: urllib.response |
| :synopsis: Response classes used by urllib. |
| |
| The :mod:`urllib.response` module defines functions and classes which define a |
| minimal file like interface, including ``read()`` and ``readline()``. The |
| typical response object is an addinfourl instance, which defines and ``info()`` |
| method and that returns headers and a ``geturl()`` method that returns the url. |
| Functions defined by this module are used internally by the |
| :mod:`urllib.request` module. |
| |