go back to clearing and pushing new address

examples/dhcp_client.rs

@@ -38,14 +38,8 @@ fn main() {
     config.random_seed = rand::random();
     let mut iface = Interface::new(config, &mut device, Instant::now());
 
-    // Initialize with an address so that there is something to mutate later.
-    // This also allows sockets made before a real address is negotiated
-    // via DHCP to update properly afterward.
-    iface.update_ip_addrs(|addrs| {
-        addrs
-            .push(IpCidr::Ipv4(Ipv4Cidr::new(Ipv4Address::UNSPECIFIED, 0)))
-            .unwrap();
-    });
+    // Initialize with an unspecified address
+    set_ipv4_addr(&mut iface, Ipv4Cidr::new(Ipv4Address::UNSPECIFIED, 0));
 
     // Create sockets
     let mut dhcp_socket = dhcpv4::Socket::new();
@@ -95,10 +89,10 @@ fn main() {
     }
 }
 
-/// Mutate the first IP address to match the one supplied
+/// Clear any existing IP addresses & add the new one
 fn set_ipv4_addr(iface: &mut Interface, cidr: Ipv4Cidr) {
     iface.update_ip_addrs(|addrs| {
-        let dest = addrs.iter_mut().next().unwrap();
-        *dest = IpCidr::Ipv4(cidr);
+        addrs.clear();
+        addrs.push(IpCidr::Ipv4(cidr)).unwrap();
     });
 }