CSCE 3530 Proxy Server

Objective

Create a web proxy server that can be connected by a single client and would only allow http requests. The proxy server should be able to cache up to six recent websites.

Requirements

• Create a C-based proxy server and a client using TCP sockets
• The proxy server should be able to accept and service single client's http requests
• The proxy server should be able to process the client's request and forward the response to the client
• The proxy server should run on cse02.cse.unt.edu machine and the client should run on cse03.cse.unt.edu machine
• The proxy server should be able to cache at least six (6) recent requested webpages, if available
• When a http request is made to a website that is cached, the proxy server should return the cached page.

Procedure

• Create a C-based server that can accept single client's request using TCP sockets
• The created proxy server should also be able to process the client HTTP request
• Make sure the proxy server runs on cse02.cse.unt.edu and the format to start the proxy server as follows

./pyserver < port_number >
where pyserver is the proxy server executable and port_number is the port number on which the proxy server listens

• Create a C-based client that can connect to the proxy server using TCP sockets
• Make sure the client runs on cse03.cse.unt.edu and connects to the proxy server. The user can request the desired web page using the below format

./client < port_number >
url: < url >
where client is the client executable, port_number is the port number on which the client connects the server and url is the requested url starting with www

• Once the proxy server gets a request from the client, it checks the cache for the requested page. If the page is not found in the cache, then it forwards the request to the web server. Figure 1 shows the overall architecture
• The proxy server checks for the response from the web server
• If the HTTP response is 200, the returned web page from the web server is cached in the proxy server. The proxy server stores the webpage in a file and assigns a filename based on the time of visit. The filename format is YYYYMMDDhhmmss. Where YYYY is the year, MM is the month, DD is the day, hh is the hour in 24-hour format, mm is the minutes, and ss is the seconds when the website was visited
• A list file (list.txt) is created which stores the URL of the webpage and the associated cached web page filename
• The list file stores six (6) recent URLs. The cached websites that are not listed in the list file should be deleted from the list file and the cache
• Once the returned web page is cached, the web page is forwarded to the client. Verify to see if the returned page is same as the browser returned page.
• If the HTTP response is not 200, do not cache the web page instead forward the HTTP response to the client
• When the client requests a webpage that is in the list.txt file (cached) the stored page is returned
• Test web caching by accessing multiple websites. Most websites are not http websites so only select http websites.
• A sample list.txt is below.

www.google.com 20210210090000
www.example.com 20210210090200
www.weevil.com 202102210090300

Figure 1. Overall Architecture see image.