Frontend improvement (#27)

* removed redundant dns lookups
* frontend now correctly reflects the state of the backend
* config.toml is loaded when starting gtk frontend

src/dns.rs

@@ -1,9 +1,20 @@
+use anyhow::Result;
 use std::{error::Error, net::IpAddr};
 
 use trust_dns_resolver::Resolver;
 
-pub fn resolve(host: &str) -> Result<Vec<IpAddr>, Box<dyn Error>> {
-    log::info!("resolving {host} ...");
-    let response = Resolver::from_system_conf()?.lookup_ip(host)?;
-    Ok(response.iter().collect())
+pub(crate) struct DnsResolver {
+    resolver: Resolver,
+}
+impl DnsResolver {
+    pub(crate) fn new() -> Result<Self> {
+        let resolver = Resolver::from_system_conf()?;
+        Ok(Self { resolver })
+    }
+
+    pub(crate) fn resolve(&self, host: &str) -> Result<Vec<IpAddr>, Box<dyn Error>> {
+        log::info!("resolving {host} ...");
+        let response = self.resolver.lookup_ip(host)?;
+        Ok(response.iter().collect())
+    }
 }