Function extract_subdomain

atomic-cli/src/commands/auth.rs:651–663

Extract the first subdomain label from a host string. `"alice.localhost"` → `Some("alice")` `"alice.atomic.storage"` → `Some("alice")` `"localhost"` → `None`

(host: &str)

/// `"alice.atomic.storage"` → `Some("alice")`
/// `"localhost"` → `None`
fn extract_subdomain(host: &str) -> Option<String> {
    // Strip port if somehow present (Url should have parsed it out, but be safe).
    let host = host.split(':').next().unwrap_or(host);

    let dot_pos = host.find('.')?;
    let subdomain = &host[..dot_pos];

    if subdomain.is_empty() {
        return None;
    }

    Some(subdomain.to_string())
}

#[cfg(test)]
mod tests {