TCP functionalities over UDP

This is a file transfer protocol which builds and demonstrates functionality of TCP. We use the UDP sockets and reliably transfer the file from client to server by implementing functionalities of TCP like checksumming and rotating window.

tcpd should be a daemon which runs on both client and server. When it is running on the client, it listens on local port to receive data from ftpc, stores the data in the wraparound buffer and sends it to troll on the local machine which sends it to server's tcpd. Once an ACK has been received from the server, it removes the packet from its buffer.

When it is running on the server, it listens on the remote port and the local port. When it receives a request from the ftp_server it enqueues it and sends the data when it receives data from the client on the remote port. Once a packet has been received from ftp client, it sends an ACK by sending it through troll on the local machine.

ftp_client is a client program which sends all the bytes of the local file to the remote ftps server

ftp_server is a server program which receives a file from a client and stores it in a folder "recvd" locally.

Timer process takes care of maintaining the delta list of the timers of the packets in the window of tcpd client buffer and notifying the tcpd client when a timer expires. Steps to compile and clean the code

To compile the code, use the following command: make

To clean the code, invoke the following command: make clean Steps to run the program

To run the tcpd, use the following command: tcpd

To run the server, use the following command: ftp_server

To run the client, use the following command: ftp_client

To run the timer, use the following command: valgrind --leak-check=yes timer