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+:mod:`http.server` --- HTTP servers
+===================================
+
+.. module:: http.server
+ :synopsis: HTTP server and request handlers.
+
+
+.. index::
+ pair: WWW; server
+ pair: HTTP; protocol
+ single: URL
+ single: httpd
+
+This module defines classes for implementing HTTP servers (Web servers).
+
+One class, :class:`HTTPServer`, is a :class:`socketserver.TCPServer` subclass.
+It creates and listens at the HTTP socket, dispatching the requests to a
+handler. Code to create and run the server looks like this::
+
+ def run(server_class=HTTPServer, handler_class=BaseHTTPRequestHandler):
+ server_address = ('', 8000)
+ httpd = server_class(server_address, handler_class)
+ httpd.serve_forever()
+
+
+.. class:: HTTPServer(server_address, RequestHandlerClass)
+
+ This class builds on the :class:`TCPServer` class by storing the server
+ address as instance variables named :attr:`server_name` and
+ :attr:`server_port`. The server is accessible by the handler, typically
+ through the handler's :attr:`server` instance variable.
+
+
+The :class:`HTTPServer` must be given a *RequestHandlerClass* on instantiation,
+of which this module provides three different variants:
+
+.. class:: BaseHTTPRequestHandler(request, client_address, server)
+
+ This class is used to handle the HTTP requests that arrive at the server. By
+ itself, it cannot respond to any actual HTTP requests; it must be subclassed
+ to handle each request method (e.g. GET or POST).
+ :class:`BaseHTTPRequestHandler` provides a number of class and instance
+ variables, and methods for use by subclasses.
+
+ The handler will parse the request and the headers, then call a method
+ specific to the request type. The method name is constructed from the
+ request. For example, for the request method ``SPAM``, the :meth:`do_SPAM`
+ method will be called with no arguments. All of the relevant information is
+ stored in instance variables of the handler. Subclasses should not need to
+ override or extend the :meth:`__init__` method.
+
+ :class:`BaseHTTPRequestHandler` has the following instance variables:
+
+ .. attribute:: client_address
+
+ Contains a tuple of the form ``(host, port)`` referring to the client's
+ address.
+
+ .. attribute:: command
+
+ Contains the command (request type). For example, ``'GET'``.
+
+ .. attribute:: path
+
+ Contains the request path.
+
+ .. attribute:: request_version
+
+ Contains the version string from the request. For example, ``'HTTP/1.0'``.
+
+ .. attribute:: headers
+
+ Holds an instance of the class specified by the :attr:`MessageClass` class
+ variable. This instance parses and manages the headers in the HTTP
+ request.
+
+ .. attribute:: rfile
+
+ Contains an input stream, positioned at the start of the optional input
+ data.
+
+ .. attribute:: wfile
+
+ Contains the output stream for writing a response back to the
+ client. Proper adherence to the HTTP protocol must be used when writing to
+ this stream.
+
+ :class:`BaseHTTPRequestHandler` has the following class variables:
+
+ .. attribute:: server_version
+
+ Specifies the server software version. You may want to override this. The
+ format is multiple whitespace-separated strings, where each string is of
+ the form name[/version]. For example, ``'BaseHTTP/0.2'``.
+
+ .. attribute:: sys_version
+
+ Contains the Python system version, in a form usable by the
+ :attr:`version_string` method and the :attr:`server_version` class
+ variable. For example, ``'Python/1.4'``.
+
+ .. attribute:: error_message_format
+
+ Specifies a format string for building an error response to the client. It
+ uses parenthesized, keyed format specifiers, so the format operand must be
+ a dictionary. The *code* key should be an integer, specifying the numeric
+ HTTP error code value. *message* should be a string containing a
+ (detailed) error message of what occurred, and *explain* should be an
+ explanation of the error code number. Default *message* and *explain*
+ values can found in the *responses* class variable.
+
+ .. attribute:: error_content_type
+
+ Specifies the Content-Type HTTP header of error responses sent to the
+ client. The default value is ``'text/html'``.
+
+ .. attribute:: protocol_version
+
+ This specifies the HTTP protocol version used in responses. If set to
+ ``'HTTP/1.1'``, the server will permit HTTP persistent connections;
+ however, your server *must* then include an accurate ``Content-Length``
+ header (using :meth:`send_header`) in all of its responses to clients.
+ For backwards compatibility, the setting defaults to ``'HTTP/1.0'``.
+
+ .. attribute:: MessageClass
+
+ .. index:: single: Message (in module mimetools)
+
+ Specifies a :class:`rfc822.Message`\ -like class to parse HTTP headers.
+ Typically, this is not overridden, and it defaults to
+ :class:`mimetools.Message`.
+
+ .. attribute:: responses
+
+ This variable contains a mapping of error code integers to two-element tuples
+ containing a short and long message. For example, ``{code: (shortmessage,
+ longmessage)}``. The *shortmessage* is usually used as the *message* key in an
+ error response, and *longmessage* as the *explain* key (see the
+ :attr:`error_message_format` class variable).
+
+ A :class:`BaseHTTPRequestHandler` instance has the following methods:
+
+ .. method:: handle()
+
+ Calls :meth:`handle_one_request` once (or, if persistent connections are
+ enabled, multiple times) to handle incoming HTTP requests. You should
+ never need to override it; instead, implement appropriate :meth:`do_\*`
+ methods.
+
+ .. method:: handle_one_request()
+
+ This method will parse and dispatch the request to the appropriate
+ :meth:`do_\*` method. You should never need to override it.
+
+ .. method:: send_error(code[, message])
+
+ Sends and logs a complete error reply to the client. The numeric *code*
+ specifies the HTTP error code, with *message* as optional, more specific text. A
+ complete set of headers is sent, followed by text composed using the
+ :attr:`error_message_format` class variable.
+
+ .. method:: send_response(code[, message])
+
+ Sends a response header and logs the accepted request. The HTTP response
+ line is sent, followed by *Server* and *Date* headers. The values for
+ these two headers are picked up from the :meth:`version_string` and
+ :meth:`date_time_string` methods, respectively.
+
+ .. method:: send_header(keyword, value)
+
+ Writes a specific HTTP header to the output stream. *keyword* should
+ specify the header keyword, with *value* specifying its value.
+
+ .. method:: end_headers()
+
+ Sends a blank line, indicating the end of the HTTP headers in the
+ response.
+
+ .. method:: log_request([code[, size]])
+
+ Logs an accepted (successful) request. *code* should specify the numeric
+ HTTP code associated with the response. If a size of the response is
+ available, then it should be passed as the *size* parameter.
+
+ .. method:: log_error(...)
+
+ Logs an error when a request cannot be fulfilled. By default, it passes
+ the message to :meth:`log_message`, so it takes the same arguments
+ (*format* and additional values).
+
+
+ .. method:: log_message(format, ...)
+
+ Logs an arbitrary message to ``sys.stderr``. This is typically overridden
+ to create custom error logging mechanisms. The *format* argument is a
+ standard printf-style format string, where the additional arguments to
+ :meth:`log_message` are applied as inputs to the formatting. The client
+ address and current date and time are prefixed to every message logged.
+
+ .. method:: version_string()
+
+ Returns the server software's version string. This is a combination of the
+ :attr:`server_version` and :attr:`sys_version` class variables.
+
+ .. method:: date_time_string([timestamp])
+
+ Returns the date and time given by *timestamp* (which must be in the
+ format returned by :func:`time.time`), formatted for a message header. If
+ *timestamp* is omitted, it uses the current date and time.
+
+ The result looks like ``'Sun, 06 Nov 1994 08:49:37 GMT'``.
+
+ .. method:: log_date_time_string()
+
+ Returns the current date and time, formatted for logging.
+
+ .. method:: address_string()
+
+ Returns the client address, formatted for logging. A name lookup is
+ performed on the client's IP address.
+
+
+.. class:: SimpleHTTPRequestHandler(request, client_address, server)
+
+ This class serves files from the current directory and below, directly
+ mapping the directory structure to HTTP requests.
+
+ A lot of the work, such as parsing the request, is done by the base class
+ :class:`BaseHTTPRequestHandler`. This class implements the :func:`do_GET`
+ and :func:`do_HEAD` functions.
+
+ The following are defined as class-level attributes of
+ :class:`SimpleHTTPRequestHandler`:
+
+ .. attribute:: server_version
+
+ This will be ``"SimpleHTTP/" + __version__``, where ``__version__`` is
+ defined at the module level.
+
+ .. attribute:: extensions_map
+
+ A dictionary mapping suffixes into MIME types. The default is
+ signified by an empty string, and is considered to be
+ ``application/octet-stream``. The mapping is used case-insensitively,
+ and so should contain only lower-cased keys.
+
+ The :class:`SimpleHTTPRequestHandler` class defines the following methods:
+
+ .. method:: do_HEAD()
+
+ This method serves the ``'HEAD'`` request type: it sends the headers it
+ would send for the equivalent ``GET`` request. See the :meth:`do_GET`
+ method for a more complete explanation of the possible headers.
+
+ .. method:: do_GET()
+
+ The request is mapped to a local file by interpreting the request as a
+ path relative to the current working directory.
+
+ If the request was mapped to a directory, the directory is checked for a
+ file named ``index.html`` or ``index.htm`` (in that order). If found, the
+ file's contents are returned; otherwise a directory listing is generated
+ by calling the :meth:`list_directory` method. This method uses
+ :func:`os.listdir` to scan the directory, and returns a ``404`` error
+ response if the :func:`listdir` fails.
+
+ If the request was mapped to a file, it is opened and the contents are
+ returned. Any :exc:`IOError` exception in opening the requested file is
+ mapped to a ``404``, ``'File not found'`` error. Otherwise, the content
+ type is guessed by calling the :meth:`guess_type` method, which in turn
+ uses the *extensions_map* variable.
+
+ A ``'Content-type:'`` header with the guessed content type is output,
+ followed by a ``'Content-Length:'`` header with the file's size and a
+ ``'Last-Modified:'`` header with the file's modification time.
+
+ Then follows a blank line signifying the end of the headers, and then the
+ contents of the file are output. If the file's MIME type starts with
+ ``text/`` the file is opened in text mode; otherwise binary mode is used.
+
+ For example usage, see the implementation of the :func:`test` function.
+
+
+.. class:: CGIHTTPRequestHandler(request, client_address, server)
+
+ This class is used to serve either files or output of CGI scripts from the
+ current directory and below. Note that mapping HTTP hierarchic structure to
+ local directory structure is exactly as in :class:`SimpleHTTPRequestHandler`.
+
+ .. note::
+
+ CGI scripts run by the :class:`CGIHTTPRequestHandler` class cannot execute
+ redirects (HTTP code 302), because code 200 (script output follows) is
+ sent prior to execution of the CGI script. This pre-empts the status
+ code.
+
+ The class will however, run the CGI script, instead of serving it as a file,
+ if it guesses it to be a CGI script. Only directory-based CGI are used ---
+ the other common server configuration is to treat special extensions as
+ denoting CGI scripts.
+
+ The :func:`do_GET` and :func:`do_HEAD` functions are modified to run CGI scripts
+ and serve the output, instead of serving files, if the request leads to
+ somewhere below the ``cgi_directories`` path.
+
+ The :class:`CGIHTTPRequestHandler` defines the following data member:
+
+ .. attribute:: cgi_directories
+
+ This defaults to ``['/cgi-bin', '/htbin']`` and describes directories to
+ treat as containing CGI scripts.
+
+ The :class:`CGIHTTPRequestHandler` defines the following method:
+
+ .. method:: do_POST()
+
+ This method serves the ``'POST'`` request type, only allowed for CGI
+ scripts. Error 501, "Can only POST to CGI scripts", is output when trying
+ to POST to a non-CGI url.
+
+ Note that CGI scripts will be run with UID of user nobody, for security
+ reasons. Problems with the CGI script will be translated to error 403.