PS/Networking — Simple C++ Sockets and Test HTTP Server

This project contains a minimal C++ socket abstraction and a simple HTTP server example that listens on localhost and returns a basic response.

Features

• SimpleSocket: wraps socket() and address setup, enables SO_REUSEADDR (and SO_REUSEPORT if available).
• BindingSocket: binds a socket to an address/port and reports errors.
• ListeningSocket: starts listen() with a configurable backlog.
• ConnectingSocket: convenience client socket (not used by the test server).
• SimpleServer: base class that owns a ListeningSocket.
• TestServer: accepts one request, prints it to stdout, and responds with a minimal HTTP/1.1 response.

Requirements

• Linux (POSIX sockets)
• g++ (tested on Fedora Linux)

Build

• Build the test server binary (uses the relative include paths in the repo):

g++ Servers/test.cpp \
    Servers/SimpleServer.cpp Servers/TestServer.cpp \
    Sockets/BindingSocket.cpp Sockets/ConnectingSocket.cpp \
    Sockets/ListeningSocket.cpp Sockets/SimpleSocket.cpp \
    -o test.exe

Optionally add warnings/standard flags:

g++ -std=c++17 -Wall -Wextra -O2 \
    Servers/test.cpp Servers/SimpleServer.cpp Servers/TestServer.cpp \
    Sockets/BindingSocket.cpp Sockets/ConnectingSocket.cpp \
    Sockets/ListeningSocket.cpp Sockets/SimpleSocket.cpp \
    -o test.exe

Run

• Start the server (default port: 8080):

./test.exe

• In another terminal, test with curl:

curl -v http://127.0.0.1:8080/

• Or open http://127.0.0.1:8080/ in a browser.

What you should see

• The server prints the incoming HTTP request to stdout, then sends a response:
  • Status: HTTP/1.1 200 OK
  • Headers: Content-Type: text/plain, Content-Length: 17, Connection: close
  • Body: "Hello from server"

Troubleshooting

• Address already in use

  • The socket is created with SO_REUSEADDR, allowing quick restarts.

  • If the port is still held by another process, end it or kill by port:

    ss -tnlp | grep :8080
    fuser -k 8080/tcp

  • Alternatively, change the server port (see below).

• Permission denied binding to port 80

  • Ports < 1024 are privileged on Linux. Use a high port (e.g., 8080), or run with elevated privileges/capabilities.

• No output in the browser

  • Ensure the server is running and listening:

    ss -tnlp | grep :8080

  • Test with curl to see the raw response (see above).

Change the port

• The port is set in Servers/TestServer.cpp in the TestServer constructor. Change 8080 to any available high port, rebuild, and rerun.

Handles one request

• The example server currently accepts a single connection, prints and responds, then exits. To handle multiple requests, wrap the accept/handle/respond sequence in a loop or spawn per-connection handlers.

Project structure

• Servers/
  • SimpleServer.hpp/.cpp: base server that owns a ListeningSocket
  • TestServer.hpp/.cpp: demo server that replies with a minimal HTTP response
  • test.cpp: program entry point
• Sockets/
  • SimpleSocket.hpp/.cpp: base socket wrapper (creates socket, sets options)
  • BindingSocket.hpp/.cpp: bind() and error checking
  • ListeningSocket.hpp/.cpp: listen() and backlog
  • ConnectingSocket.hpp/.cpp: connect() helper