ToyWebServer

Distributed System Programming Assignment

telnet

• older and unsafer than ssh
• by default, disabled by Windows

telnet google.com 80

GET / HTTP/1.1

Single-threaded Python Web Server

"""
 Implements a simple HTTP/1.0 Server
"""

import os
import socket

#Get current directory
currentPath = os.getcwd().replace('\\','/')   

def handle_request(request):
    """Handles the HTTP request."""

    headers = request.split('\n')
    filename = headers[0].split()[1]
    if filename == '/':
        filename = '/index.html'

    try:
        fin = open(currentPath + filename)
        content = fin.read()
        fin.close()

        response = 'HTTP/1.0 200 OK\n\n' + content
    except FileNotFoundError:
        response = 'HTTP/1.0 404 NOT FOUND\n\nFile Not Found'

    return response


# Define socket host and port
SERVER_HOST = '0.0.0.0'
SERVER_PORT = 8080

# Create socket
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind((SERVER_HOST, SERVER_PORT))
server_socket.listen(1)
print('Listening on port %s ...' % SERVER_PORT)

while True:
    # Wait for client connections
    client_connection, client_address = server_socket.accept()

    # Get the client request
    request = client_connection.recv(1024).decode()
    print(request)

    # Return an HTTP response
    response = handle_request(request)
    client_connection.sendall(response.encode())

    # Close connection
    client_connection.close()

# Close socket
server_socket.close()

Multi-threaded Python Web Server

import socket
import threading
import os

#Get current directory
currentPath = os.getcwd().replace('\\','/')    
# 多线程服务器

def handle_conn(sock, address):
    print("deal with connection ....")
    t = threading.Thread(target=process_conn, args=(sock, address))
    t.start()


def process_conn(sock, address):
    print(threading.current_thread())

    while True:  # 多次为一个客户端服务
        recv_data = sock.recv(1024)
        # 如果 recv 解堵塞，客户端有两种方式 1. 发送了数据 2. 关闭了连接
        if recv_data:
            # 回送数据到客户端
            # 最好使用 sendall
        
            request=recv_data.decode()
            print(request)

            headers = request.split('\n')
            filename = headers[0].split()[1]

    
            if filename == '/':
                filename = '/index.html'

            try:
                fin = open(currentPath+filename)
                content = fin.read()
                fin.close()

                response = 'HTTP/1.0 200 OK\n\n' + content
            except FileNotFoundError:
                response = 'HTTP/1.0 404 NOT FOUND\n\nFile Not Found'    

            # Return an HTTP response
            sock.sendall(response.encode())        
        else:
            break
    # 5. close socket
    print("close socket..")
    sock.close()


def main():
    # 1. create socket
    tcp_server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    # 2. bind local information
    tcp_server_socket.bind(("127.0.0.1", 8888))
    # 3.
    tcp_server_socket.listen()
    # 4. accept connection from client
    # 类似你在等待别人的电话到来
    # 元组解包
    while True:
        print(threading.current_thread())
        print("waitting ........")
        new_client_socket, client_addr = tcp_server_socket.accept()
        handle_conn(new_client_socket, client_addr)


if __name__ == '__main__':
    main()

another local example

server:

# import socket programming library
import socket

# import thread module
from _thread import *
import threading

print_lock = threading.Lock()

# thread function
def threaded(c):
	while True:

		# data received from client
		data = c.recv(1024)
		if not data:
			print('Bye')
			
			# lock released on exit
			print_lock.release()
			break

		# reverse the given string from client
		data = data[::-1]

		# send back reversed string to client
		c.send(data)

	# connection closed
	c.close()


def Main():
	host = ""

	# reserve a port on your computer
	# in our case it is 8888 but it
	# can be anything
	port = 8888
	s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	s.bind((host, port))
	print("socket binded to port", port)

	# put the socket into listening mode
	s.listen(5)
	print("socket is listening")

	# a forever loop until client wants to exit
	while True:

		# establish connection with client
		c, addr = s.accept()

		# lock acquired by client
		print_lock.acquire()
		print('Connected to :', addr[0], ':', addr[1])

		# Start a new thread and return its identifier
		start_new_thread(threaded, (c,))
	s.close()


if __name__ == '__main__':
	Main()

client:

# Import socket module
import socket


def Main():
	# local host IP '127.0.0.1'
	host = '127.0.0.1'

	# Define the port on which you want to connect
	port = 8888

	s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

	# connect to server on local computer
	s.connect((host,port))

	# message you send to server
	message = "shaurya says geeksforgeeks"
	while True:

		# message sent to server
		s.send(message.encode('ascii'))

		# message received from server
		data = s.recv(1024)

		# print the received message
		# here it would be a reverse of sent message
		print('Received from the server :',str(data.decode('ascii')))

		# ask the client whether he wants to continue
		ans = input('\nDo you want to continue(y/n) :')
		if ans == 'y':
			continue
		else:
			break
	# close the connection
	s.close()

if __name__ == '__main__':
	Main()

unsolved

1. why the exception handler is not working?
2. why can’t open plain text(txt) file?
3. why more than one threads assigned to a single user?

import socket
import threading
import os

#Get current directory
currentPath = os.getcwd().replace('\\','/')    
# multithreaded server

def handle_conn(sock, address):
    print("deal with connection ....")
    t = threading.Thread(target=process_conn, args=(sock, address))
    t.start()


def process_conn(sock, address):
    print(threading.current_thread())

    while True:  # serve one client multiple times
        recv_data = sock.recv(1024)
        
        # until there is no incoming request
        if recv_data:
            
        
            request=recv_data.decode()
            print(request)

            headers = request.split('\n')
            filename = headers[0].split()[1]

            headers = "HTTP/1.1 200 OK\n" + "Content-Type: text/html\n\n"
            # access HTML file
            if filename == '/':
                filename = '/index.html'
            # access jpg image file
            elif filename.endswith(".jpg") :
                headers = "HTTP/1.1 200 OK\n" + "Content-Type: image/jpeg\n\n"
            # access txt file
            elif filename.endswith(".txt") :
                headers = "HTTP/1.1 200 OK\n" + "Content-Type: text/plain\n\n"
            
                
            #     headers = "HTTP/1.1 200 OK\n" + "Content-Type: text/html\n\n"
            #     fin = open(currentPath+filename, "rb")
            #     content = fin.read()
            #     fin.close()
            #     sock.send(headers.encode())
            #     sock.send(content)
            # elif filename.endswith(".jpg") :
            #     is_img=True
            #     headers = "HTTP/1.1 200 OK\n" + "Content-Type: image/jpeg\n\n"
            #     fin = open(currentPath+filename, "rb")
            #     content = fin.read()
            #     fin.close()
            #     sock.send(headers.encode())
            #     sock.send(content)
            try:
                
                # is_img or not:
                fin = open(currentPath+filename, "rb")
                content = fin.read()
                fin.close()
                response=headers.encode()+content
                # sock.send(headers.encode())
                # sock.send(content)

            #     else :
            #         fin = open(currentPath+filename, "r")
            #         content = fin.read()
            #         fin.close()
            #         sock.send(headers.encode())
            #         sock.send(content.encode())
                
                # content = fin.read()
                # fin.close()

                #response = 'HTTP/1.0 200 OK\n\n' + content

            # Error Handling
            except FileNotFoundError:
                response = 'HTTP/1.0 404 NOT FOUND\n\nFile Not Found'.encode()    
            except PermissionError:
                response = 'HTTP/1.0 403 FORBIDDEN\n\nNo Access Permission'.encode()
                    
            # Return an HTTP response
            
            sock.send(response)
            # sock.sendall((headers + content).encode())        
        else:
            break
    # 5. close socket
    print("close socket..")
    sock.close()


def main():
    # 1. create socket
    tcp_server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    # 2. bind local information
    tcp_server_socket.bind(("127.0.0.1", 8888))
    # 3.
    tcp_server_socket.listen(5)
    
    # 4. wait and accept connection from client
    while True:
        print(threading.current_thread())
        print("waitting ........")
        new_client_socket, client_addr = tcp_server_socket.accept()
        handle_conn(new_client_socket, client_addr)


if __name__ == '__main__':
    main()