feat: yt-dlp YouTube import has no URL validation before invoking the binary — passing a malformed URL or a non-YouTube URL causes a cryptic yt-dlp error that surfaces as an unhandled exception in the Rust backend

[prince-pokharna]

🐛 Problem Statement

Knowte's YouTube import feature accepts a URL pasted by the user and passes it directly to the bundled yt-dlp binary. If the user pastes:

• A non-URL string (my lecture notes)
• A non-YouTube URL (https://vimeo.com/123456)
• A private/unavailable video URL

...yt-dlp exits with a non-zero code. Without explicit error handling on the yt-dlp process exit, this either panics in Rust or returns an opaque error to the frontend.

💡 Proposed Fix

1. Validate URL format and domain before invoking yt-dlp (Rust)

// src-tauri/src/downloader.rs

use url::Url; // add `url` crate to Cargo.toml

const ALLOWED_DOMAINS: &[&str] = &[
    "youtube.com",
    "youtu.be",
    "www.youtube.com",
    "m.youtube.com",
];

pub fn validate_youtube_url(raw_url: &str) -> Result<String, String> {
    let parsed = Url::parse(raw_url)
        .map_err(|_| "Invalid URL format. Please paste a valid YouTube link.".to_string())?;

    let host = parsed
        .host_str()
        .unwrap_or("")
        .trim_start_matches("www.");

    if !ALLOWED_DOMAINS.iter().any(|d| d.trim_start_matches("www.") == host) {
        return Err(format!(
            "'{}' is not a supported source. Only YouTube URLs are currently supported.",
            host
        ));
    }

    Ok(raw_url.to_string())
}

2. Handle yt-dlp non-zero exit codes explicitly

let output = Command::new(&yt_dlp_path)
    .args(["-x", "--audio-format", "mp3", "-o", &output_path, &validated_url])
    .output()
    .map_err(|e| format!("Failed to launch yt-dlp: {}", e))?;

if !output.status.success() {
    let stderr = String::from_utf8_lossy(&output.stderr);
    return Err(format!("Download failed: {}", stderr));
}

📁 Files to Modify

File	Change
src-tauri/src/downloader.rs	Add URL validation + yt-dlp exit code handling
src-tauri/Cargo.toml	Add url crate dependency
src/	Display user-friendly error message from Tauri

Suggested labels: bug, tauri, ux, validation

I would like to work on this. Could you please assign it to me?

[prince-pokharna]

Hey @maintainers,
Please assign it to me under GSSoC 2026
/claim /assign /claim-assignment