Improve netif client data API for lwIP internal clients - these can use a compile-time constant to access their data now

src/include/lwip/autoip.h

@@ -84,7 +84,6 @@ void autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr);
 void autoip_tmr(void);
 void autoip_network_changed(struct netif *netif);
 u8_t autoip_supplied_address(const struct netif *netif);
-void autoip_init(void);
 
 /* for lwIP internal use by ip4.c */
 u8_t autoip_accept_packet(struct netif *netif, const ip4_addr_t *addr);

src/include/lwip/dhcp.h

@@ -118,10 +118,6 @@ u8_t dhcp_supplied_address(const struct netif *netif);
 void dhcp_coarse_tmr(void);
 /* to be called every half second */
 void dhcp_fine_tmr(void);
-void dhcp_init(void);
-
-/* for use in unit tests only */
-extern u8_t dhcp_netif_client_id;
 
 #if LWIP_DHCP_GET_NTP_SRV
 /** This function must exist, in other to add offered NTP servers to

src/include/lwip/netif.h

@@ -104,6 +104,17 @@ extern "C" {
  * @}
  */
 
+enum lwip_internal_netif_client_data_index
+{
+#if LWIP_DHCP
+   LWIP_NETIF_CLIENT_DATA_INDEX_DHCP,
+#endif
+#if LWIP_AUTOIP
+   LWIP_NETIF_CLIENT_DATA_INDEX_AUTOIP,
+#endif
+   LWIP_NETIF_CLIENT_DATA_INDEX_MAX
+};
+
 #if LWIP_CHECKSUM_CTRL_PER_NETIF
 #define NETIF_CHECKSUM_GEN_IP       0x0001
 #define NETIF_CHECKSUM_GEN_UDP      0x0002
@@ -237,8 +248,8 @@ struct netif {
   /** This field can be set by the device driver and could point
    *  to state information for the device. */
   void *state;
-#if LWIP_NUM_NETIF_CLIENT_DATA > 0
-  void* client_data[LWIP_NUM_NETIF_CLIENT_DATA];
+#if LWIP_DHCP || LWIP_AUTOIP || (LWIP_NUM_NETIF_CLIENT_DATA > 0)
+  void* client_data[LWIP_NETIF_CLIENT_DATA_INDEX_MAX + LWIP_NUM_NETIF_CLIENT_DATA];
 #endif
 #if LWIP_IPV6_AUTOCONFIG
   /** is this netif enabled for IPv6 autoconfiguration */

src/include/lwip/opt.h

@@ -1468,10 +1468,10 @@
 
 /**
  * LWIP_NUM_NETIF_CLIENT_DATA: Number of clients that may store
- * per data in client_data member array of struct netif.
+ * data in client_data member array of struct netif.
  */
 #if !defined LWIP_NUM_NETIF_CLIENT_DATA || defined __DOXYGEN__
-#define LWIP_NUM_NETIF_CLIENT_DATA            (LWIP_DHCP + LWIP_AUTOIP)
+#define LWIP_NUM_NETIF_CLIENT_DATA            0
 #endif
 /**
  * @}