udp-client-server

Goal and requirements

The goal was to write a program that communicates between client and server using the UDP protocol.

The requirements were:

1. Use e-poll both on the server, as well as client side
2. Sent file should preserve its name
3. Client should see the file transfer speed
4. Server should be able to handle multiple clients simultaneously

Usage

Server and client are split into separate programs

Compiling

Server

gcc -server.c -o server.out

Client

gcc -client.c -o client.out

Running

Server

./server.out <PORT>

Received files are stored in ./receive directory

Client

./client.out <PORT> <FILE_NAME>

for individual file, or

bash run_multiple_clients.sh

for sending 2 provided example text files.

The file should be a text file, be in the ./ directory, and passed to the program just as the name (not full path)

Implementation and design

For now not all requirements are completely met.

1. The program is slightly simplified by only communicating in one direction - client sends files to the server. Hence, there implementing e-poll on the client side was not a priority.

2. Files preserve their names. Also when sent across multiple packets and in-between other files. This is done by reserving first 3 bytes for the file name length followed by the file name.

3. The sendto() command is timed on the client's side, and that is displayed as the transfer speed. To avoid cluttering stdout with tons of messages, the previous one is re-written.

4. Use of e-poll as well as the strategy for figuring out to which file data belongs allows handling multiple clients.

Bugs and to-do

• Implement two-way communication
• There is an issue with the last character in the buffer
• Only text files can be sent in multiple packets
• Improve transfer speed display
• Generalize hard-coded values as constants in consts.h
• Checksum for packet verification