fix: address review comments - CIDR validation, dhcp_cidr implies DHCP, fmt fixes

easytier/src/common/config.rs

@@ -765,7 +765,8 @@ impl ConfigLoader for TomlConfigLoader {
     }
 
     fn get_dhcp(&self) -> bool {
-        self.config.lock().unwrap().dhcp.unwrap_or_default()
+        let config = self.config.lock().unwrap();
+        config.dhcp.unwrap_or_default() || config.dhcp_cidr.is_some()
     }
 
     fn set_dhcp(&self, dhcp: bool) {

easytier/src/core.rs

@@ -915,9 +915,15 @@ impl NetworkOptions {
             } else {
                 // Treat as CIDR, e.g. "10.0.0.0/24"
                 cfg.set_dhcp(true);
-                let cidr: cidr::Ipv4Cidr = dhcp.parse().with_context(|| {
-                    format!("failed to parse dhcp cidr: {}", dhcp)
-                })?;
+                let cidr: cidr::Ipv4Cidr = dhcp
+                    .parse()
+                    .with_context(|| format!("failed to parse dhcp cidr: {}", dhcp))?;
+                if cidr.network_length() > 30 {
+                    anyhow::bail!(
+                        "dhcp cidr prefix length must be <= 30, got /{}",
+                        cidr.network_length()
+                    );
+                }
                 cfg.set_dhcp_cidr(Some(cidr));
             }
         }

easytier/src/launcher.rs

@@ -638,9 +638,16 @@ impl NetworkConfig {
         cfg.set_hostname(self.hostname.clone());
         cfg.set_dhcp(self.dhcp.unwrap_or_default());
         if let Some(ref dhcp_cidr) = self.dhcp_cidr {
-            let cidr = dhcp_cidr.parse::<cidr::Ipv4Cidr>().with_context(|| {
-                format!("failed to parse dhcp_cidr: {}", dhcp_cidr)
-            })?;
+            let cidr = dhcp_cidr
+                .parse::<cidr::Ipv4Cidr>()
+                .with_context(|| format!("failed to parse dhcp_cidr: {}", dhcp_cidr))?;
+            if cidr.network_length() > 30 {
+                anyhow::bail!(
+                    "dhcp_cidr prefix length must be <= 30, got /{}",
+                    cidr.network_length()
+                );
+            }
+            cfg.set_dhcp(true);
             cfg.set_dhcp_cidr(Some(cidr));
         }
         cfg.set_inst_name(self.network_name.clone().unwrap_or_default());