ipconfig: lwip: Add support for autoconf4 configuration.

greezybacon · greezybacon · commit ff08f0f68834 · 2025-07-18T08:28:30.000-05:00
Auto IP configuration is a method of picking a random IP address in the
169.254.0.0/16 subnet. It is analogous to the IPv6 stateless
autoconfiguration on link-local interfaces.

It's actually recommended by LwIP for use with mDNS and is useful for
networks where devices should be configured without a DHCP server and
then discovered by name via mDNS.

Currently only implemented for the LWIP software IP stack.

Signed-off-by: Jared Hancock &lt;jared.hancock@centeredsolutions.com&gt;
diff --git a/docs/library/network.rst b/docs/library/network.rst
@@ -124,6 +124,11 @@ parameter should be `id`.
          server via DHCP. This method does not block and wait for an address
          to be obtained. To check if an address was obtained, use the read-only
          property ``has_dhcp4``.
+       * ``autoconf4`` (``True/False``) obtain an IPv4 address randomly in the
+         169.254.0.0/16 address space. This method does not block and wait for
+         an address to be selected and confirmed to be unused on the network. To
+         check if an address has been selected, use the read-only property
+         ``has_autoconf4``.
        * ``gw4`` Get/set the IPv4 default-gateway.
        * ``dhcp6`` (``True/False``) obtain a DNS server via stateless DHCPv6.
          Obtaining IP Addresses via DHCPv6 is currently not implemented.
diff --git a/extmod/network_lwip.c b/extmod/network_lwip.c
@@ -39,6 +39,7 @@
 
 #include "lwip/netif.h"
 #include "lwip/timeouts.h"
+#include "lwip/autoip.h"
 #include "lwip/dns.h"
 #include "lwip/dhcp.h"
 #include "lwip/nd6.h"
@@ -191,6 +192,11 @@ mp_obj_t mod_network_nic_ipconfig(struct netif *netif, size_t n_args, const mp_o
             case MP_QSTR_has_dhcp4: {
                 return mp_obj_new_bool(dhcp_supplied_address(netif));
             }
+            #if LWIP_AUTOIP
+            case MP_QSTR_has_autoconf4: {
+                return mp_obj_new_bool(autoip_supplied_address(netif));
+            }
+            #endif
             #if LWIP_IPV6_DHCP6
             case MP_QSTR_dhcp6: {
                 struct dhcp6 *dhcp = netif_dhcp6_data(netif);
@@ -268,13 +274,24 @@ mp_obj_t mod_network_nic_ipconfig(struct netif *netif, size_t n_args, const mp_o
                                 dhcp_renew(netif);
                             } else {
                                 dhcp_release_and_stop(netif);
+                                #if LWIP_AUTOIP
+                                if (autoip_supplied_address(netif)) {
+                                    autoip_stop(netif);
+                                }
+                                #endif
                                 dhcp_start(netif);
                             }
                         } else {
                             dhcp_release_and_stop(netif);
                         }
                         break;
                     }
+                    #if LWIP_AUTOIP
+                    case MP_QSTR_autoconf4: {
+                        dhcp_release_and_stop(netif);
+                        autoip_start(netif);
+                    }
+                    #endif
                     #if LWIP_IPV6_DHCP6
                     case MP_QSTR_dhcp6: {
                         dhcp6_disable(netif);
