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Networking
NET-1: Echo Server

NET-1: Echo Server

Requirements

  • Write a C/C++ TCP echo server program that:

    • Creates a TCP socket and binds it to a specified port (default: 8080)
    • Listens for incoming client connections
    • Accepts a client connection and echoes back any data received from the client
    • Handles the client until the connection is closed, then waits for the next client
    • Prints connection information (client IP address and port) when a client connects
    • The server should run indefinitely until terminated with Ctrl+C

  • Write a C/C++ TCP client program that:

    • Connects to the echo server at a specified IP address and port
    • Reads user input from stdin and sends it to the server
    • Receives the echoed response from the server and prints it
    • Continues until the user types “exit” or closes stdin (Ctrl+D)

  • Both programs must use the BSD socket API (socket(), bind(), listen(), accept(), connect(), send(), recv(), close())

  • Use proper byte order conversion (htons(), inet_pton(), etc.)

  • Handle errors appropriately (check return values of all socket calls)

Expected result

The resulting applications should be able to build and execute from command line as follows:

make
./echo-server 8080

In a separate terminal, run the client:

./echo-client 127.0.0.1 8080

Server terminal output:

[Server] Listening on port 8080...
[Server] Client connected from 127.0.0.1:54321
[Server] Received: Hello, World!
[Server] Echoed: Hello, World!
[Server] Received: Testing sockets
[Server] Echoed: Testing sockets
[Server] Client disconnected.
[Server] Waiting for next client...

Client terminal output:

[Client] Connected to 127.0.0.1:8080
> Hello, World!
[Server]: Hello, World!
> Testing sockets
[Server]: Testing sockets
> exit
[Client] Disconnecting...

Bonus (Optional)

  • Support multiple concurrent clients using fork() or threads
  • Add a command-line option to specify the server’s listening address (not just port)
  • Implement a simple protocol: prefix each message with its length

Deliverables

The final solution should contain a Makefile for building both programs. The Makefile should contain targets:

  • all — build both server and client
  • echo-server — build only the server
  • echo-client — build only the client
  • clean — remove compiled binaries

It’s recommended to have compiler and compiler flags declared as Makefile variables. Alternatively, cmake could also be used instead of make.

Networking