Python Simplified HTTP Server

This repository contains a lightweight, custom-built server implemented in Python using raw sockets. It serves as an implementation of a simplified HTTP/1.1 protocol. This project was developed as part of Lab 2 for ECE358: Computer Networks.

Overview

The goal of this project is to parse bytes sent between a client and a server to facilitate plain text data transfer. The server handles request parsing, validates headers, and issues appropriate HTTP responses and status codes based on the requested operations.

Supported HTTP Methods

The server implements the following HTTP verbs:

• GET: Retrieves the raw bytes of a requested resource. Returns a 200 OK on success or a 404 Not Found if the file does not exist.
• HEAD: Functions identically to GET, but returns only the headers (including Content-Length) and omits the message body.
• POST: Processes incoming plain text data directed to the simple_form path. It parses a username:description formatted string and echoes the data back to the client.
• PUT: Allows clients to create new files or overwrite existing ones strictly within the /user/ directory.
• DELETE: Removes a specified resource from the /user/ directory. This method implements a basic authentication scheme, requiring a base64 encoded username and password sent via the Authorization: Basic header, which is verified against a local users.txt file.

Supported Status Codes

The server handles specific success and error states, intentionally omitting 5xx server errors for simplicity:

• 200 OK: Request succeeded; response body contains the result.
• 201 Created: New resource created successfully (used in POST and PUT).
• 400 Bad Request: Request could not be understood due to malformed syntax.
• 401 Unauthorized: Client authentication is missing or incorrect (used in DELETE).
• 403 Forbidden: Client is authenticated but not allowed to perform the action (e.g., trying to delete outside the /user/ folder).
• 404 Not Found: Resource does not exist at the given URI.
• 405 Method Not Allowed: The requested method is not supported by the server.

Protocol Simplifications & Constraints

To focus on the core mechanics of HTTP, this implementation includes several specific constraints:

• No Encryption: Uses plain HTTP, not HTTPS.
• Size Limits: All messages (including headers and body) are restricted to a maximum length of 1024 bytes.
• Data Type: The server strictly transfers plain text in utf-8 format.
• File System Roots: The / path refers to the root directory of the server script, not the root of the host machine's file system.
• Host Header: While clients must format requests to include a Host header, the server parses it but does not implement multiple host routing.

Usage

1. Clone the repository.
2. Ensure you have Python 3 installed.
3. Run the server script (python3 server.py), which binds to localhost (127.0.0.1) on port 8000.
4. Ensure a users.txt file and a /user/ directory exist in the server's root folder for DELETE and PUT operations to function correctly.
5. To see sample requests and responses being sent and returned from the server, uncomment a line of code in the client.py file and run the script (python3 client.py) to run a test.