proxyserver2.py

from socket import *
import sys

if len(sys.argv) <= 1:
    print('Usage : "python ProxyServer.py server_ip"\n[server_ip : It is the IP Address Of Proxy Server')
    sys.exit(2)

# Create a server socket, bind it to a port and start listening
tcpSerSock = socket(AF_INET, SOCK_STREAM)
tcpSerPort = 8888
tcpSerSock.bind(("", tcpSerPort))
tcpSerSock.listen(5)


while 1:
    # Start receiving data from the client
    print('Listening and Ready to serve...')
    tcpCliSock, addr = tcpSerSock.accept()
    print('Received a connection from:', addr)
    message = tcpCliSock.recv(1024)
    print(message)
    # Extract the filename from the given message
    print(message.split()[1])
    filename = message.split()[1].partition("/")[2]
    print(filename)
    fileExist = "false"
    filetouse = "/" + filename
    print(filetouse)
    try:
        # Check wether the file exist in the cache
        f = open(filetouse[1:], "r")
        outputdata = f.readlines()
        fileExist = "true"
        # ProxyServer finds a cache hit and generates a response message
        tcpCliSock.send("HTTP/1.0 200 OK\r\n")
        tcpCliSock.send("Content-Type:text/html\r\n")
        # Fill in start.
        for i in range(0, len(outputdata)):
            tcpCliSock.send(outputdata[i])
            # Fill in end.
            print('Read from cache')
    # Error handling for file not found in cache
    except IOError:
        if fileExist == "false":
            # Create a socket on the proxyserver
            c = socket(AF_INET, SOCK_STREAM)  # Fill in start. Fill in end.
            hostn = filename.replace("www.", "", 1)
            print(hostn)
            try:
                # Connect to the socket to port 80
                # Fill in start.
                c.connect((hostn, 80))
                # Fill in end.
                # Create a temporary file on this socket and ask port 80 for the file requested by the client
                fileobj = c.makefile('r', 0)
                fileobj.write("GET " + "http://" + filename + "HTTP/1.0\n\n")
                # Read the response into buffer
                # Fill in start.
                buff = fileobj.readlines()
                # Fill in end.
                # Create a new file in the cache for the requested file.
                # Also send the response in the buffer to client socket and the corresponding file in the cache
                tmpFile = open("./" + filename, "wb")
                # Fill in start.
                for i in range(0, len(buff)):
                    tmpFile.write(buff[i])
                    tcpCliSock.send(buff[i])
                # Fill in end.
            except:
                print("Illegal request")
        else:
            # HTTP response message for file not found
            # Fill in start.
            print("404 Error file not found")
            # Fill in end.
    # Close the client and the server sockets
    tcpCliSock.close()
if __name__ == "__main__":
    main()

# proxyserver2.py 127.0.0.1
# http://localhost:8888/www.yahoo.com