SSL File Downloader in C

This project is a simple SSL file downloader written in C. The program connects to a remote server over HTTPS, sends an HTTP GET request, and downloads the specified file. The downloaded file is saved locally as downloaded_file.txt.

The project utilizes OpenSSL for handling the SSL/TLS connections and includes basic error handling for networking and SSL-related operations.

Features

• Connects to an HTTPS server using SSL/TLS.
• Sends a GET request to download a file.
• Parses the HTTP response to skip the headers.
• Saves the file content to a local file named downloaded_file.txt.

Prerequisites

To build and run this project, you'll need:

• GCC (or any C compiler)
• OpenSSL library

Building the Project

To compile the code, run the following command:

gcc -o ssl-file-downloader ssl-file-downloader.c -lssl -lcrypto

This will produce an executable named ssl-file-downloader.

Running the Program

Once compiled, you can run the program using:

./ssl-file-downloader

This will download the file from the specified URL (https://raw.githubusercontent.com/SalamLang/Salam/main/src/array.c) and save it as downloaded_file.txt in the current directory.

Installing OpenSSL (Linux)

If OpenSSL is not installed, you can install it using the following command:

sudo apt-get install libssl-dev

Code Explanation

• SSL Initialization: The program initializes the OpenSSL library and sets up an SSL context using the TLS_client_method() function.
• Socket Setup: The program resolves the hostname using getaddrinfo() and establishes a connection to the server using socket() and connect().
• SSL Connection: An SSL object is created and associated with the socket file descriptor using SSL_set_fd(). The program then performs an SSL handshake using SSL_connect().
• HTTP Request and Response Handling: The program sends a GET request to the server and reads the response. It searches for the end of the HTTP headers and begins writing the file content to downloaded_file.txt.
• Cleanup: After the download is complete, the program releases all resources, including closing the file, the SSL connection, and the socket.

Important Notes

• Hardcoded URL: The hostname and file path are currently hardcoded in the source code. Modify these variables to download different files.
• File Output: The downloaded file is saved as downloaded_file.txt. Ensure that the program has write permissions in the directory where it is executed.

License

This project is licensed under the GPL-3.0 License. See the LICENSE file for more details.

Author

Max Base

Contributions

Contributions, issues, and feature requests are welcome! Feel free to check the issues page if you have any questions or suggestions.

Copyright 2024, Max Base