store DnsServer in GlobalCtx, load routes from DnsServer in ProxyCidrsMonitor

easytier/src/instance/proxy_cidrs_monitor.rs

@@ -1,4 +1,5 @@
 use std::collections::BTreeSet;
+use std::net::IpAddr;
 use std::sync::{Arc, Weak};
 use std::time::Instant;
 
@@ -54,6 +55,13 @@ impl ProxyCidrsMonitor {
             proxy_cidrs = routes.into_iter().collect();
         }
 
+        if let Some(dns) = global_ctx.get_dns() {
+            proxy_cidrs.extend(dns.addresses().into_iter().filter_map(|a| match a.ip() {
+                IpAddr::V4(ip) => Some(cidr::Ipv4Cidr::new_host(ip)),
+                _ => None,
+            }))
+        }
+
         // Calculate diff
         if cur_proxy_cidrs == &proxy_cidrs {
             return (proxy_cidrs, Vec::new(), Vec::new());