sbktckp/computer-networks

Purpose and Scope

This is a C17 Computer Networks lab repository. The present assignment teaches low-level C concepts needed for networking work: pointer mutation, struct passing semantics, byte-level representation, packet reconstruction, and host endianness.

Entry Points and Execution

Each .c source file is an independently runnable program with its own main. The repository-level run launcher selects a question and optionally its compact variant; it forwards remaining CLI arguments to the selected executable. Makefile builds all programs and cleans generated binaries.

Core entry paths:

• run

• Makefile

• Assignment 2 - C Basics and Endianness/README.md

Assignment Module Layout

Assignment 2 is organized as five numbered exercises, with a full instructional implementation at the assignment root and a behavior-equivalent minimal implementation in compact/.

Primary module paths:

• Assignment 2 - C Basics and Endianness/2.1_swap_pointer.c

• Assignment 2 - C Basics and Endianness/2.2_struct_call_by_value_address.c

• Assignment 2 - C Basics and Endianness/2.3_byte_extraction.c

• Assignment 2 - C Basics and Endianness/2.4_struct_pkt_reassemble.c

• Assignment 2 - C Basics and Endianness/2.5_endianness_check.c

Pointer and Struct Semantics

The first two programs establish C memory and parameter-passing behavior. The pointer swap exercise mutates caller-owned values through addresses, while the struct exercise contrasts a copied struct received by value against mutation through a struct address.

Relevant paths:

• Assignment 2 - C Basics and Endianness/2.1_swap_pointer.c

• Assignment 2 - C Basics and Endianness/2.2_struct_call_by_value_address.c

• Assignment 2 - C Basics and Endianness/compact/2.2_struct_call_by_value_address.c

Byte Representation and Packet Assembly

The byte extraction exercise interprets an integer’s individual bytes, using unsigned-byte handling to avoid signed-extension issues. The packet reassembly exercise is the assignment’s networking-oriented boundary: it combines component byte fields into a reconstructed structured packet/value representation.

Relevant paths:

• Assignment 2 - C Basics and Endianness/2.3_byte_extraction.c

• Assignment 2 - C Basics and Endianness/2.4_struct_pkt_reassemble.c

• Assignment 2 - C Basics and Endianness/compact/2.4_struct_pkt_reassemble.c

Endianness Boundary

Host byte order is explicitly detected rather than assumed, using a union-based probe. This connects in-memory integer layout to network-data interpretation and complements extraction/reassembly behavior.

Relevant paths:

• Assignment 2 - C Basics and Endianness/2.5_endianness_check.c

• Assignment 2 - C Basics and Endianness/compact/2.5_endianness_check.c

Runtime and Build Constraints

Programs target standard C17 and compile with GCC under warning-focused flags (-Wall -Wextra -Wpedantic). The intended runtime environments are Codespaces, WSL, Linux, and macOS; no application server, database, or external network service is involved. Full sources prioritize explanatory comments; compact sources preserve output while minimizing implementation size.

Relevant paths:

• Assignment 2 - C Basics and Endianness/compact/README.md

• Makefile

• run