Proxy Server Project in C

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Introduction

This project is a simple HTTP proxy server written in C. It intercepts HTTP requests from clients and forwards them to the destination servers. The proxy can filter content based on configurable rules, log requests, and manage configurations dynamically.

Features

• HTTP Proxy Server: Handles HTTP requests and responses between clients and servers.
• Content Filtering: Blocks access to specified domains or content based on keywords and configurable rules.
• Logging: Records proxy activities, requests, and errors in a log file.
• Dynamic Configuration: Loads configuration parameters and filtering rules from external files.

Directory Structure

.
├── includes                 // Header files for the modules
│   ├── config.h
│   ├── http_helper.h
│   ├── logger.h
│   ├── rules.h
│   ├── server.h
│   └── utils.h
├── main.c                   // The main entry point of the proxy 
├── Makefile                 // Instructions for building the project
├── obj/                     // Directory where object files are stored after compilation
├── conf/                    // Directory where config file are stored
│   ├── proxy.config         // Configuration file for the proxy server
│   └── proxy.rules          // Rules file defining filtering criteria
├── logs/
│   └──proxy.log             // Log file where activities are recorded
├── README.md
├── src                      // Source files implementing the functionality
│   ├── config.c
│   ├── http_helper.c
│   ├── logger.c
│   ├── rules.c
│   ├── server.c
│   └── utils.c
├── Doxyfile                 // Configuration file for doxygen
├── Doxygen.md               // Main page for doxygen doc generation
├── docs/html/index.html     // Entry point of the documentation
└── test/                    // Directory where test source files are
    ├── test_http_helper.c
    └── test_server.c

Installation

Prerequisites

• GCC Compiler
• Make utility
• Standard C libraries
• Doxygen (for documentation generation)

Building the Project

1. Clone the Repository

git clone https://github.com/Grolleau-Benjamin/proxy-server-C.git

2. Navigate to the Project Directory

cd proxy-server-C

3. Build the Project

Two ways are available to build the project:

• Standard Build

  Run the basic make command to compile the source code:

  make

• Debug Build

  Run the make debug command to compile the source code in debug mode:

  make debug

This compiles the source files and generates an executable proxy or proxy_debug, depending on the command.

4. Run Tests (Optional)

Run make test to execute all tests and verify if the program is working as expected.

make test

5. Generate Documentation

Run the make docs command to generate the project's documentation using Doxygen:

make docs

The documentation will be generated in the docs/ directory. You can open the docs/html/index.html file in your web browser to view the documentation.

6. Clean Build (Optional)

To clean up object files and executables:

make clean

Configuration

proxy.config

The proxy.config file contains configuration parameters for the proxy server. The default parameters are:

# Configuration file for the proxy server

PORT 8080
ADDRESS 127.0.0.1
MAX_CLIENT 10
LOGGER_FILENAME proxy.log
RULES_FILENAME proxy.rules

Parameters

• PORT: The port number on which the proxy server listens.
• ADDRESS: The IPv4 address on which the proxy server is bound.
• MAX_CLIENT: The maximum number of simultaneous client connections.
• LOGGER_FILENAME: The file where logs are recorded.
• RULES_FILENAME: The file containing filtering rules.

Modifying Configuration

Edit the proxy.config file to change the proxy server's settings. The server reads this file at startup, so don't forget to restart it to apply changes.

proxy.rules

The proxy.rules file defines the filtering rules used by the proxy to block or allow content.

Rules Format

The rules are defined in a simple format:

[Category]
# List of banned domains
BAN_DOMAIN example.com
BAN_DOMAIN badsite.com
# List of banned words
BAN_WORD forbidden
BAN_WORD secret

Rules Types

• BAN_DOMAIN: Blocks access to the specified domain.
• BAN_WORD: Blocks content containing the specified keyword.

Applying Rules

The proxy server loads rules at startup and applies these rules to each HTTP request it processes.

Usage

1. Start the Proxy Server

Run ./proxy or ./proxy_debug after building it. The server will start listening on the configured address and port.

2. Configure Clients to Use the Proxy

Set up your web browser or HTTP client to use the proxy server. For example, configure the proxy settings to 127.0.0.1:8080.

3. Access HTTP Websites

Use the client to browse websites as usual. The proxy will handle the requests according to the defined rules.

Logging

• Log File: The proxy activities are recorded in the file specified by LOGGER_FILENAME in proxy.config (default is proxy.log).
• Log Levels: The proxy records information, warnings, and errors.

Generating Documentation

The project's documentation is generated using Doxygen, which helps in understanding the code and modules. To generate the documentation, ensure that Doxygen is installed, then run:

make docs

The documentation will be generated in the docs/ directory. Open docs/html/index.html in your web browser to view it.

License

This project is licensed under the MIT License. See the LICENSE file for details.