address_family = socket.AF_INET

socket_type = socket.SOCK_STREAM

request_queue_size = 1

def __init__(self, server_address):

# Create a listening socket

self.listen_socket = listen_socket = socket.socket(

self.address_family,

self.socket_type

)

# Allow to reuse the same address

listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

# Bind

listen_socket.bind(server_address)

# Activate

listen_socket.listen(self.request_queue_size)

# Get server host name and port

host, port = self.listen_socket.getsockname()[:2]

self.server_name = socket.getfqdn(host)

self.server_port = port

# Return headers set by Web framework/Web application

self.headers_set = []

def set_app(self, application):

self.application = application

def serve_forever(self):

listen_socket = self.listen_socket

while True:

# New client connection

self.client_connection, client_address = listen_socket.accept()

# Handle one request and close the client connection. Then

# loop over to wait for another client connection

self.handle_one_request()

def handle_one_request(self):

request_data = self.client_connection.recv(1024)

self.request_data = request_data = request_data.decode('utf-8')

# Print formatted request data a la 'curl -v'

print(''.join(

f'< {line}\n' for line in request_data.splitlines()

))

self.parse_request(request_data)

# Construct environment dictionary using request data

env = self.get_environ()

# It's time to call our application callable and get

# back a result that will become HTTP response body

result = self.application(env, self.start_response)

# Construct a response and send it back to the client

self.finish_response(result)

def parse_request(self, text):

request_line = text.splitlines()[0]

request_line = request_line.rstrip('\r\n')

# Break down the request line into components

(self.request_method, # GET

self.path, # /hello

self.request_version # HTTP/1.1

) = request_line.split()

def get_environ(self):

env = {}

# The following code snippet does not follow PEP8 conventions

# but it's formatted the way it is for demonstration purposes

# to emphasize the required variables and their values

#

# Required WSGI variables

env['wsgi.version'] = (1, 0)

env['wsgi.url_scheme'] = 'http'

env['wsgi.input'] = io.StringIO(self.request_data)

env['wsgi.errors'] = sys.stderr

env['wsgi.multithread'] = False

env['wsgi.multiprocess'] = False

env['wsgi.run_once'] = False

# Required CGI variables

env['REQUEST_METHOD'] = self.request_method # GET

env['PATH_INFO'] = self.path # /hello

env['SERVER_NAME'] = self.server_name # localhost

env['SERVER_PORT'] = str(self.server_port) # 8888

return env

def start_response(self, status, response_headers, exc_info=None):

# Add necessary server headers

server_headers = [

('Date', 'Mon, 15 Jul 2019 5:54:48 GMT'),

('Server', 'WSGIServer 0.2'),

]

self.headers_set = [status, response_headers + server_headers]

# To adhere to WSGI specification the start_response must return

# a 'write' callable. We simplicity's sake we'll ignore that detail

# for now.

# return self.finish_response

def finish_response(self, result):

try:

status, response_headers = self.headers_set

response = f'HTTP/1.1 {status}\r\n'

for header in response_headers:

response += '{0}: {1}\r\n'.format(*header)

response += '\r\n'

for data in result:

response += data.decode('utf-8')

# Print formatted response data a la 'curl -v'

print(''.join(

f'> {line}\n' for line in response.splitlines()

))

response_bytes = response.encode()

self.client_connection.sendall(response_bytes)

finally: