Multi Threaded Proxy Server with and without Cache

Index

• Project Theory
• How to Run

Project Theory

Basic Working Flow of the Proxy Server:

How did we implement Multi-threading?

• Used Semaphore instead of Condition Variables and pthread_join() and pthread_exit() function.
• pthread_join() requires us to pass the thread id of the the thread to wait for.
• Semaphore’s sem_wait() and sem_post() doesn’t need any parameter. So it is a better option.

Motivation/Need of Project

• To Understand →
  • The working of requests from our local computer to the server.
  • The handling of multiple client requests from various clients.
  • Locking procedure for concurrency.
  • The concept of cache and its different functions that might be used by browsers.
• Proxy Server do →
  • It speeds up the process and reduces the traffic on the server side.
  • It can be used to restrict user from accessing specific websites.
  • A good proxy will change the IP such that the server wouldn’t know about the client who sent the request.
  • Changes can be made in Proxy to encrypt the requests, to stop anyone accessing the request illegally from your client.

OS Component Used ​

• Threading
• Locks
• Semaphore
• Cache (LRU algorithm is used in it)

Limitations ​

• If a URL opens multiple clients itself, then our cache will store each client’s response as a separate element in the linked list. So, during retrieval from the cache, only a chunk of response will be send and the website will not open
• Fixed size of cache element, so big websites may not be stored in cache.

How this project can be extended? ​

• This code can be implemented using multiprocessing that can speed up the process with parallelism.
• We can decide which type of websites should be allowed by extending the code.
• We can implement requests like POST with this code.

Note :-

• Code is well commented. For any doubt you can refer to the comments.

How to Run

$ git clone https://github.com/vishalmishraa/MultithreadedProxyWebServer.git
$ cd MultithreadedProxyWebServer
$ make all
$ ./proxy <port no.>

Open http://localhost:port/https://www.cs.princeton.edu/

Note:

• This code can only be run in Linux Machine. Please disable your browser cache.
• To run the proxy without cache Change the name of the file (proxy_server_with_cache.c to proxy_server_without_cache.c) MakeFile.