Computer Networks Lab

Weekly codes for the Computer Networks lab. Each week gets its own folder with a full version of every program and a compact/ subfolder with the shortest version that still works. Every program is directly executable in the terminal, no manual gcc command needed.

Run in your Codespace terminal

Open this repo in GitHub Codespaces (Code button -> Codespaces -> Create codespace on main). The devcontainer installs gcc, make, and the C/C++ extension automatically, so the terminal is ready as soon as the codespace loads. No setup step is needed.

Once the terminal is open, there are three ways to run any program:

1. Run a program directly (fastest, one command per question):

Every block below jumps to the repo root first, so it is copy-paste safe regardless of where your terminal currently is, and restores the executable bit before running (it doesn't survive a fresh clone).

cd "/workspaces/Computer-Networks/Lab 2 - C Basics and Endianness"
chmod +x run_*
./run_2.1_swap_pointer 10 25

cd "/workspaces/Computer-Networks/Lab 3 - Socket Programming"
chmod +x run_*
./run_3.1_tcp_server 9090       # start this first, in its own terminal

cd "/workspaces/Computer-Networks/Lab 3 - Socket Programming"
chmod +x run_*
./run_3.2_tcp_client 127.0.0.1 9090   # then this, in a second terminal

cd "/workspaces/Computer-Networks/Lab 4 - TCP Client-Server Programs"
chmod +x run_*
./run_4.4_echo_server 9090      # start this first, in its own terminal

cd "/workspaces/Computer-Networks/Lab 4 - TCP Client-Server Programs"
chmod +x run_*
./run_4.4_echo_client 127.0.0.1 9090  # then this, in a second terminal

cd "/workspaces/Computer-Networks/Lab 5 - TCP Chat Application"
chmod +x run_*
./run_5.1_chat_server           # start this first, in its own terminal

cd "/workspaces/Computer-Networks/Lab 5 - TCP Chat Application"
chmod +x run_*
./run_5.1_chat_client            # then this, in a second terminal

cd "/workspaces/Computer-Networks/Lab 6 - Concurrent Chat Server"
chmod +x run_*
./run_6.1_concurrent_chat_server         # start this first, in its own terminal

cd "/workspaces/Computer-Networks/Lab 6 - Concurrent Chat Server"
chmod +x run_*
./run_6.1_concurrent_chat_client          # then this, in a second (or third...) terminal

cd "/workspaces/Computer-Networks/Lab 7 - UDP Client-Server Programs"
chmod +x run_*
./run_7.2_calculator_server 9072      # start this first, in its own terminal

cd "/workspaces/Computer-Networks/Lab 7 - UDP Client-Server Programs"
chmod +x run_*
./run_7.2_calculator_client 127.0.0.1 9072  # then this, in a second terminal

cd "/workspaces/Computer-Networks/Lab Test-1"
chmod +x run_*
./run_1.1_calculator_server 9191      # start this first, in its own terminal

cd "/workspaces/Computer-Networks/Lab Test-1"
chmod +x run_*
./run_1.1_calculator_client 127.0.0.1 9191  # then this, in a second terminal

cd "/workspaces/Computer-Networks/Lab 8 - UDP Calculator Client-Server"
chmod +x run_*
./run_8.1_calculator_server 9080      # start this first, in its own terminal

cd "/workspaces/Computer-Networks/Lab 8 - UDP Calculator Client-Server"
chmod +x run_*
./run_8.1_calculator_client 127.0.0.1 9080  # then this, in a second terminal

Client/server programs like Lab 3, Lab 4, Lab 5, Lab 6, Lab 7, Lab 8, and Lab Test-1 need two terminal tabs open at once, one running the server, one running the client against it (Lab 6 can take three or more, to show several clients chatting at once). See that week's README for the exact walkthrough.

Every run_* script compiles fresh each time it runs, so editing the .c file and re-running picks up the change immediately.

2. Use the repo-wide ./run helper (works from the repo root):

cd /workspaces/Computer-Networks
chmod +x run
./run                      # list every program in the repo, grouped by week
./run 2.1                   # Lab 2, full version of question 2.1
./run compact/2.1           # Lab 2, compact version of question 2.1
./run 3.1                    # Lab 3, the server
./run 3.2 127.0.0.1 9090        # Lab 3, the client, with arguments forwarded
./run 4.4_echo_server            # Lab 4, question 4.4's server (server/client share
./run 4.4_echo_client            # a numeric prefix, so use the full name to pick one)
./run 5.1_chat_server                # Lab 5, chat server
./run 5.1_chat_client                # Lab 5, chat client
./run 6.1_concurrent_chat_server         # Lab 6, concurrent server
./run 6.1_concurrent_chat_client         # Lab 6, chat client (run several at once)
./run 7.2_calculator_server          # Lab 7, question 7.2's server (server/client share
./run 7.2_calculator_client          # a numeric prefix, so use the full name to pick one)
./run 1.1_calculator_server         # Lab Test-1, calculator server
./run 1.1_calculator_client         # Lab Test-1, calculator client
./run 8.1_calculator_server          # Lab 8, integer UDP calculator server (loops
./run 8.1_calculator_client          # forever, serves multiple clients sequentially)

3. Use make (builds every program in every week at once into bin/):

cd /workspaces/Computer-Networks
make            # builds bin/<week>/<program> for every week folder
./bin/"Lab 2 - C Basics and Endianness"/2.1_swap_pointer 10 25
make clean      # removes bin/

Or click Run in the editor: open any .c file, press the triangle at the top right. This compiles and runs just that file.

These commands assume the standard Codespaces path, /workspaces/Computer-Networks. If you cloned it elsewhere (WSL, native Linux, macOS), replace that path with wherever you cloned the repo, or just cd into the repo yourself first and use the relative folder name instead. Everything targets standard C17, so all three methods behave identically everywhere.

Weeks

Week	Folder	Topic
2	Lab 2 - C Basics and Endianness	Pointers, structs, byte extraction, endianness
3	Lab 3 - Socket Programming	TCP sockets in C: server and client, interactive session
4	Lab 4 - TCP Client-Server Programs	Six client/server pairs: connection basics, client info, one-way messaging, echo, uppercase, reverse
5	Lab 5 - TCP Chat Application	Interactive two-way TCP chat, ends on "logout" from either side
6	Lab 6 - Concurrent Chat Server	fork()-based concurrent chat server: one child process per client, per-client "logout", client IP printed with each message
7	Lab 7 - UDP Client-Server Programs	Six UDP client/server pairs: message + ack, calculator, string reversal, even/odd checker, uppercase, continuous exchange
8	Lab 8 - UDP Calculator Client-Server	Integer UDP calculator: server loops forever serving clients sequentially, prints client IP, handles division-by-zero and unsupported operators; cross-platform (Winsock + BSD sockets)
Lab Test 1	Lab Test-1	TCP calculator (+, -, *, /, division-by-zero handling), TCP word count

Full vs Compact

Full versions are commented for understanding: they explain why each choice works (call-by-value copying the whole struct, SO_REUSEADDR avoiding a bind failure on restart, inet_pton over inet_addr), not just what the code does.

Compact versions are the shortest code that still compiles clean under -Wall -Wextra -Wpedantic and produces the same output, using a loop wherever the full version does. Each compact file's header comment carries a real sample run, and each has its own run_* wrapper, so it stands on its own without needing the full version for context.