Source code: Lib/http/server.py
This module defines classes for implementing HTTP servers (Web servers).
def run(server_class=HTTPServer, handler_class=BaseHTTPRequestHandler): server_address = ('', 8000) httpd = server_class(server_address, handler_class) httpd.serve_forever()
class http.server.HTTPServer(server_address, RequestHandlerClass)
This class builds on the
TCPServer class by storing the server address as instance variables named
server_port. The server is accessible by the handler, typically through the handler’s
server instance variable.
HTTPServer must be given a RequestHandlerClass on instantiation, of which this module provides three different variants:
class http.server.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).
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
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
BaseHTTPRequestHandler has the following instance variables:
Contains a tuple of the form
(host, port) referring to the client’s address.
Contains the server instance.
Boolean that should be set before
handle_one_request() returns, indicating if another request may be expected, or if the connection should be shut down.
Contains the string representation of the HTTP request line. The terminating CRLF is stripped. This attribute should be set by
handle_one_request(). If no valid request line was processed, it should be set to the empty string.
Contains the command (request type). For example,
Contains the request path.
Contains the version string from the request. For example,
Holds an instance of the class specified by the
MessageClass class variable. This instance parses and manages the headers in the HTTP request. The
parse_headers() function from
http.client is used to parse the headers and it requires that the HTTP request provide a valid RFC 2822 style header.
io.BufferedIOBase input stream, ready to read from the start of the optional input data.
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.
Changed in version 3.6: This is an
BaseHTTPRequestHandler has the following attributes:
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,
Specifies a format string that should be used by
send_error() method for building an error response to the client. The string is filled by default with variables from
responses based on the status code that passed to
Specifies the Content-Type HTTP header of error responses sent to the client. The default value is
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
send_header()) in all of its responses to clients. For backwards compatibility, the setting defaults to
email.message.Message-like class to parse HTTP headers. Typically, this is not overridden, and it defaults to
This attribute contains a mapping of error code integers to two-element tuples containing a short and long message. For example,
longmessage)}. The shortmessage is usually used as the message key in an error response, and longmessage as the explain key. It is used by
BaseHTTPRequestHandler instance has the following methods:
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
This method will parse and dispatch the request to the appropriate
do_*() method. You should never need to override it.
When a HTTP/1.1 compliant server receives an
Expect: 100-continue request header it responds back with a
100 Continue followed by
OK headers. This method can be overridden to raise an error if the server does not want the client to continue. For e.g. server can chose to send
Expectation Failed as a response header and
New in version 3.2.
send_error(code, message=None, explain=None)
Sends and logs a complete error reply to the client. The numeric code specifies the HTTP error code, with message as an optional, short, human readable description of the error. The explain argument can be used to provide more detailed information about the error; it will be formatted using the
error_message_format attribute and emitted, after a complete set of headers, as the response body. The
responses attribute holds the default values for message and explain that will be used if no value is provided; for unknown codes the default value for both is the string
???. The body will be empty if the method is HEAD or the response code is one of the following:
204 No Content,
205 Reset Content,
304 Not Modified.
Changed in version 3.4: The error response includes a Content-Length header. Added the explain argument.
Adds a response header to the headers buffer and logs the accepted request. The HTTP response line is written to the internal buffer, followed by Server and Date headers. The values for these two headers are picked up from the
date_time_string() methods, respectively. If the server does not intend to send any other headers using the
send_header() method, then
send_response() should be followed by an
Changed in version 3.3: Headers are stored to an internal buffer and
end_headers() needs to be called explicitly.
Adds the HTTP header to an internal buffer which will be written to the output stream when either
flush_headers() is invoked. keyword should specify the header keyword, with value specifying its value. Note that, after the send_header calls are done,
end_headers() MUST BE called in order to complete the operation.
Changed in version 3.2: Headers are stored in an internal buffer.
Sends the response header only, used for the purposes when
Continue response is sent by the server to the client. The headers not buffered and sent directly the output stream.If the message is not specified, the HTTP message corresponding the response code is sent.
New in version 3.2.
Adds a blank line (indicating the end of the HTTP headers in the response) to the headers buffer and calls
Changed in version 3.2: The buffered headers are written to the output stream.
Finally send the headers to the output stream and flush the internal headers buffer.
New in version 3.3.
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.
Logs an error when a request cannot be fulfilled. By default, it passes the message to
log_message(), so it takes the same arguments (format and additional values).
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
log_message() are applied as inputs to the formatting. The client ip address and current date and time are prefixed to every message logged.
Returns the date and time given by timestamp (which must be
None or in the format returned by
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'.
Returns the current date and time, formatted for logging.
Returns the client address.
Changed in version 3.3: Previously, a name lookup was performed. To avoid name resolution delays, it now always returns the IP address.
class http.server.SimpleHTTPRequestHandler(request, client_address, server)
This class serves files from the current directory and below, directly mapping the directory structure to HTTP requests.
The following are defined as class-level attributes of
This will be
"SimpleHTTP/" + __version__, where
__version__ is defined at the module level.
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.
SimpleHTTPRequestHandler class defines the following methods:
This method serves the
'HEAD' request type: it sends the headers it would send for the equivalent
GET request. See the
do_GET() method for a more complete explanation of the possible headers.
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.htm (in that order). If found, the file’s contents are returned; otherwise a directory listing is generated by calling the
list_directory() method. This method uses
os.listdir() to scan the directory, and returns a
404 error response if the
If the request was mapped to a file, it is opened and the contents are returned. Any
OSError exception in opening the requested file is mapped to a
'File not found' error. Otherwise, the content type is guessed by calling the
guess_type() method, which in turn uses the extensions_map variable.
'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.
SimpleHTTPRequestHandler class can be used in the following manner in order to create a very basic webserver serving files relative to the current directory:
import http.server import socketserver PORT = 8000 Handler = http.server.SimpleHTTPRequestHandler with socketserver.TCPServer(("", PORT), Handler) as httpd: print("serving at port", PORT) httpd.serve_forever()
python -m http.server 8000
By default, server binds itself to all interfaces. The option
-b/--bind specifies a specific address to which it should bind. For example, the following command causes the server to bind to localhost only:
python -m http.server 8000 --bind 127.0.0.1
New in version 3.4:
--bind argument was introduced.
class http.server.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
CGI scripts run by the
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.
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
CGIHTTPRequestHandler defines the following data member:
This defaults to
['/cgi-bin', '/htbin'] and describes directories to treat as containing CGI scripts.
CGIHTTPRequestHandler defines the following method:
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.
CGIHTTPRequestHandler can be enabled in the command line by passing the
python -m http.server --cgi 8000
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