DHCP Allows selecting the DHCP server's network interface

This changes the parameters of dhcpserver_start.

  Besides that, dhcpserver_start should only be called after user_init has
finished, else the call sdk_system_get_netif(SOFTAP_IF) will return NULL.

examples/access_point/access_point.c

@@ -48,10 +48,6 @@ void user_init(void)
     };
     sdk_wifi_softap_set_config(&ap_config);
 
-    ip_addr_t first_client_ip;
-    IP4_ADDR(&first_client_ip, 172, 16, 0, 2);
-    dhcpserver_start(&first_client_ip, 4);
-
     xTaskCreate(telnetTask, "telnetTask", 512, NULL, 2, NULL);
 }
 
@@ -60,6 +56,10 @@ void user_init(void)
 */
 static void telnetTask(void *pvParameters)
 {
+  ip_addr_t first_client_ip;
+  IP4_ADDR(&first_client_ip, 172, 16, 0, 2);
+  dhcpserver_start(sdk_system_get_netif(SOFTAP_IF), &first_client_ip, 4);
+
   struct netconn *nc = netconn_new (NETCONN_TCP);
   if(!nc) {
     printf("Status monitor: Failed to allocate socket.\r\n");

extras/dhcpserver/dhcpserver.c

@@ -77,8 +77,12 @@ inline static void sprintf_ipaddr(const ip_addr_t *addr, char *dest)
                 ip4_addr2(addr), ip4_addr3(addr), ip4_addr4(addr));
 }
 
-void dhcpserver_start(const ip_addr_t *first_client_addr, uint8_t max_leases)
+void dhcpserver_start(struct netif *server_if, const ip_addr_t *first_client_addr, uint8_t max_leases)
 {
+    if(!server_if){
+        printf("DHCP Server Error: server_if is NULL.\r\n");
+        return;
+    }
     /* Stop any existing running dhcpserver */
     if(dhcpserver_task_handle)
         dhcpserver_stop();
@@ -89,7 +93,7 @@ void dhcpserver_start(const ip_addr_t *first_client_addr, uint8_t max_leases)
     // state->server_if is assigned once the task is running - see comment in dhcpserver_task()
     ip_addr_copy(state->first_client_addr, *first_client_addr);
 
-    xTaskCreate(dhcpserver_task, "DHCPServer", 768, NULL, 8, &dhcpserver_task_handle);
+    xTaskCreate(dhcpserver_task, "DHCPServer", 768, server_if, 8, &dhcpserver_task_handle);
 }
 
 void dhcpserver_stop(void)
@@ -104,7 +108,7 @@ void dhcpserver_stop(void)
 static void dhcpserver_task(void *pxParameter)
 {
     /* netif_list isn't assigned until after user_init completes, which is why we do it inside the task */
-    state->server_if = netif_list; /* TODO: Make this configurable */
+    state->server_if = pxParameter;
 
     state->nc = netconn_new (NETCONN_UDP);
     if(!state->nc) {

extras/dhcpserver/include/dhcpserver.h

@@ -25,8 +25,10 @@ extern "C" {
    first_client_addr is the IP address of the first lease to be handed
    to a client.  Subsequent lease addresses are calculated by
    incrementing the final octet of the IPv4 address, up to max_leases.
+
+   The server will wait for requests on server_if interface.
 */
-void dhcpserver_start(const ip_addr_t *first_client_addr, uint8_t max_leases);
+void dhcpserver_start(struct netif *server_if, const ip_addr_t *first_client_addr, uint8_t max_leases);
 
 void dhcpserver_get_lease(const ip_addr_t *first_client_addr, uint8_t max_leases);
 

tests/cases/04_wifi_basic.c

@@ -40,6 +40,11 @@ DEFINE_TESTCASE(04_wifi_basic, DUAL)
 
 static void server_task(void *pvParameters)
 {
+
+    ip_addr_t first_client_ip;
+    IP4_ADDR(&first_client_ip, 172, 16, 0, 2);
+    dhcpserver_start(sdk_system_get_netif(SOFTAP_IF), &first_client_ip, 4);
+
     char buf[BUF_SIZE];
     struct netconn *nc = netconn_new(NETCONN_TCP);
     TEST_ASSERT_TRUE_MESSAGE(nc != 0, "Failed to allocate socket");
@@ -103,10 +108,6 @@ static void a_04_wifi_basic(void)
     };
     sdk_wifi_softap_set_config(&ap_config);
 
-    ip_addr_t first_client_ip;
-    IP4_ADDR(&first_client_ip, 172, 16, 0, 2);
-    dhcpserver_start(&first_client_ip, 4);
-
     xTaskCreate(server_task, "setver_task", 1024, NULL, 2, NULL);
 }