hostname_resolver 0.1.0

Validate hostname
Documentation 
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//! DNS Module
//!
//! This module check whether a hostname + domain resolves to
//! an ip-address.
//!

pub mod dns {

    use anyhow::{Context, Result};
    use azure_vault_secrets::Vault;
    use azure_vault_secrets::VaultStorage;
    use db_config::db_config_from_vault;
    use hickory_resolver::error::ResolveError;
    use hickory_resolver::system_conf::read_system_conf;
    use hickory_resolver::AsyncResolver;

    /// # Arguments
    ///
    /// * `vault` - Name of the variable with values from Azure Key Vault
    ///
    /// # Returns
    ///
    /// A Result containing the resolved hostname + domainname if successful,
    /// or an error if the hostname + domainname could not be resolved.
    ///
    pub async fn check_dns(vault: &Vault) -> Result<()> {
        db_config_from_vault!([host, user, name, pwd, domain]);

        let (cfg, opts) = read_system_conf().map_err(|e| ResolveError::from(e))?;
        let resolver = AsyncResolver::tokio(cfg, opts);
        let config = DatabaseConfig::from_vault(vault)?;

        let hostname = format!("{}.{}.", &config.host(), &config.domain());

        let response = resolver
            .lookup_ip(&hostname)
            .await
            .with_context(|| format!("Failed to resolve hostname: {}", hostname))?;

        if response.iter().next().is_none() {
            anyhow::bail!("No IP address found for hostname: {}", hostname);
        }

        Ok(())
    }
}