Python standard library: http.server

Adding headers to HTTP response

In order to use the SharedArrayBuffer object, the two HTTP response headers Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy must be set to same-origin and require-corp.

If these header are not set or set to a different value, the following simple HTML page alerts the user that SharedArrayBuffer is not supported:

<script>
   if (typeof(SharedArrayBuffer) === 'undefined') {
      alert('SharedArrayBuffer is not supported');
   }
   else {
      alert('SharedArrayBuffer IS supported');
   }
</script>

The following script sets the two required headers so that the browser does support SharedArrayBuffer:

from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer

class serveWithHeaders(SimpleHTTPRequestHandler):

    def end_headers(self):
        self.addHeaders()

        SimpleHTTPRequestHandler.end_headers(self)

    def addHeaders(self):
        self.send_header('Cross-Origin-Opener-Policy',   'same-origin' )
        self.send_header('Cross-Origin-Embedder-Policy', 'require-corp')

httpd = ThreadingHTTPServer( ('', 8000), serveWithHeaders)

httpd.serve_forever()

BaseHTTPRequestHandler

Interesting functions and properties

log_message(format, ...) logs a message to sys.stderr. This method is typically overwritten to customize logging.

Not production ready

As per the documentation, http.server implements only basic security checks and is therefore not production ready.

Some possible problems are addressed in this Stack Exchange/Information Security question.

Some notes on the code

The constructor of BaseServer takes

a server_address and a
RequestHandlerClass (of which an object is intantiated for each request. This class should/must implement handle(). I believe it must inherit from socketserver.BaseRequestHandler)

The constructor of (the derived class) TCPServer additionally takes the

optional boolean value bind_and_activate

The (derived classes) http.HTTPServer and http.ThreadingHTTPServer do not have an explicit constructor.

BaseRequestHandler is the base class for objects that handle requests.

This object is instantiated in the method BaseServer.finish_request.

BaseServer.serve_forever() handles one request at a time until shutdown.

serve_forever() calls BaseServer._handle_request_noblock() to handle a request.

BaseServer._handle_request_noblock()

calls self.get_request() (which returns request (a socket object) and client_address)
calls calls self.process_request() and passes request and client_address to this method.

BaseServer.process_request() calls

self.finish_request() and
self.shutdown_request()

BaseServer.finish_request()

instantiates in instance of the RequestHandlerClass that was passed to the the constructor of HTTPServer

StreamRequestHandler does not override handle().

StreamRequestHandler.setup() creates the members rfile and wfile.

class BaseHTTPRequestHandler

derives from StreamRequestHandler (which in turn derives from BaseRequestHandler
does not seem to have an explicit constructor

BaseHTTPRequestHandler.handle() calls handle_one_request() until self.close_connection is True.

BaseHTTPRequestHandler.handle_one_request() (which normally does not need to be overridden) handles one HTTP request.

This method

reads the request line (for example GET /index.html HTTP/1.0)
Calls self.parse_request()
Calls do_XYZ (where XYZ is the request type), for example do_GET.

BaseHTTPRequestHandler.parse_request()

Sets request_line
Determines the HTTP request version and stores it in request_version
Sets command and path
Calls http.client.parse_headers and sets headers

The constructor of BaseRequestHandler

takes request (a socket object), client_address and server.

The constructor of TCPServer

passes the server address and the «RequestHandlerClass» to the parent's class (BaseServer) constructor
instantiates the member socket with a socket.socket object.

TCPServer.get_request() calls self.socket.accept() which returns request (a socket object) and client_address.

TODO

Is Python 2 SimpleHTTPServer merged into http.server in Python 3?