feat(lwip): softap can get sta ip from arp table

components/esp_netif/include/esp_netif.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2019-2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2019-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -682,7 +682,19 @@ esp_err_t esp_netif_dhcps_stop(esp_netif_t *esp_netif);
  */
 esp_err_t esp_netif_dhcps_get_clients_by_mac(esp_netif_t *esp_netif, int num, esp_netif_pair_mac_ip_t *mac_ip_pair);
 
-
+/**
+ * @brief  Populate IP addresses of client from the lwIP ARP cache on this interface
+ *
+ * Walks the ARP table and fills in ip when the Ethernet address matches and the entry belongs to esp_netif.
+ *
+ * @param[in] esp_netif Handle to esp-netif instance
+ * @param[in,out] mac_ip_pair MAC/IP pair to fill in the IP
+ * @return
+ *      - ESP_OK on success (including when nothing was found in ARP)
+ *      - ESP_ERR_ESP_NETIF_INVALID_PARAMS on invalid params
+ *      - ESP_ERR_NOT_SUPPORTED if ARP is disabled in lwIP
+ */
+esp_err_t esp_netif_arp_get_client_by_mac(esp_netif_t *esp_netif, esp_netif_pair_mac_ip_t *mac_ip_pair);
 
 /**
  * @brief  Set DNS Server information

components/esp_netif/lwip/esp_netif_lwip.c

@@ -2053,6 +2053,52 @@ esp_err_t esp_netif_dhcps_get_clients_by_mac(esp_netif_t *esp_netif, int num, es
 #endif // CONFIG_LWIP_DHCPS
 }
 
+#if CONFIG_LWIP_IPV4 && LWIP_ARP
+static esp_err_t esp_netif_arp_get_client_by_mac_api(esp_netif_api_msg_t *msg)
+{
+    esp_netif_t *esp_netif = msg->esp_netif;
+    esp_netif_pair_mac_ip_t *mac_ip_pair = msg->data;
+    struct netif *lwip_netif = esp_netif ? esp_netif->lwip_netif : NULL;
+
+    if (lwip_netif == NULL || mac_ip_pair == NULL) {
+        return ESP_ERR_ESP_NETIF_INVALID_PARAMS;
+    }
+
+    mac_ip_pair->ip.addr = 0;
+
+    for (size_t i = 0; i < ARP_TABLE_SIZE; i++) {
+        ip4_addr_t *ip_ptr = NULL;
+        struct netif *nif = NULL;
+        struct eth_addr *eth_ptr = NULL;
+
+        if (!etharp_get_entry(i, &ip_ptr, &nif, &eth_ptr)) {
+            continue;
+        }
+        if (nif != lwip_netif) {
+            continue;
+        }
+        if (memcmp(eth_ptr->addr, mac_ip_pair->mac, ETH_HWADDR_LEN) != 0) {
+            continue;
+        }
+        mac_ip_pair->ip.addr = ip_ptr->addr;
+        break;
+    }
+    return ESP_OK;
+}
+#endif /* CONFIG_LWIP_IPV4 && LWIP_ARP */
+
+esp_err_t esp_netif_arp_get_client_by_mac(esp_netif_t *esp_netif, esp_netif_pair_mac_ip_t *mac_ip_pair)
+{
+#if CONFIG_LWIP_IPV4 && LWIP_ARP
+    if (esp_netif == NULL || mac_ip_pair == NULL) {
+        return ESP_ERR_ESP_NETIF_INVALID_PARAMS;
+    }
+    return esp_netif_lwip_ipc_call(esp_netif_arp_get_client_by_mac_api, esp_netif, (void *)mac_ip_pair);
+#else
+    return ESP_ERR_NOT_SUPPORTED;
+#endif /* CONFIG_LWIP_IPV4 && LWIP_ARP */
+}
+
 static esp_err_t esp_netif_set_dns_info_api(esp_netif_api_msg_t *msg)
 {
     esp_netif_t *esp_netif = msg->esp_netif;

components/esp_wifi/include/esp_wifi_ap_get_sta_list.h

@@ -36,7 +36,8 @@ typedef struct {
 /**
  * @brief  Get IP information for stations connected to the Wi-Fi AP interface
  *
- * @note   If `CONFIG_LWIP_DHCPS` is disabled then `ip` address field will not be populated in sta list
+ * @note   If `CONFIG_LWIP_DHCPS` is disabled then DHCP lookup is skipped; IPv4 may still be filled from the lwIP ARP cache when available.
+ *         After DHCP (when enabled), any station still without an IP is resolved via ARP table on the same interface.
  *
  * @warning This API works only for the default Wi-Fi AP interface, i.e. esp-netif with key="WIFI_AP_DEF"
  *

components/esp_wifi/remote/include/injected/esp_wifi_ap_get_sta_list.h

@@ -0,0 +1,56 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include "esp_netif_types.h"
+#include "esp_wifi_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef ESP_WIFI_MAX_CONN_NUM
+// Number of maximum wifi connection may be undefined if we have no native wifi support on this target
+//   and at the same time there's no native interface injected by the wifi_remote component.
+// In this case, we just let the header compilable, since no wifi API could be used (let's make a sanity check)
+#if !CONFIG_SOC_WIFI_SUPPORTED && !CONFIG_ESP_WIFI_REMOTE_ENABLED && !CONFIG_ESP_HOST_WIFI_ENABLED
+#define ESP_WIFI_MAX_CONN_NUM  (15)
+typedef struct wifi_sta_list_t wifi_sta_list_t;
+#else
+#error WiFi header mismatch! Please make sure you use the correct version of WiFi API
+#endif
+#endif // ESP_WIFI_MAX_CONN_NUM
+
+/**
+ * @brief station list structure
+ */
+typedef struct {
+    int num;                                                /**< Number of connected stations */
+    esp_netif_pair_mac_ip_t sta[ESP_WIFI_MAX_CONN_NUM];     /**< Connected stations */
+} wifi_sta_mac_ip_list_t;
+
+/**
+ * @brief  Get IP information for stations connected to the Wi-Fi AP interface
+ *
+ * @note   If `CONFIG_LWIP_DHCPS` is disabled then DHCP lookup is skipped; IPv4 may still be filled from the lwIP ARP cache when available.
+ *         After DHCP (when enabled), any station still without an IP is resolved via ARP table on the same interface.
+ *
+ * @warning This API works only for the default Wi-Fi AP interface, i.e. esp-netif with key="WIFI_AP_DEF"
+ *
+ * @param[in]   wifi_sta_list Wi-Fi station info list, returned from esp_wifi_ap_get_sta_list()
+ * @param[out]  wifi_sta_ip_mac_list IP layer station info list, corresponding to MAC addresses provided in wifi_sta_list
+ *
+ * @return
+ *         - ESP_OK
+ *         - ESP_ERR_ESP_NETIF_NO_MEM
+ *         - ESP_ERR_ESP_NETIF_INVALID_PARAMS
+ */
+esp_err_t esp_wifi_ap_get_sta_list_with_ip(const wifi_sta_list_t *wifi_sta_list, wifi_sta_mac_ip_list_t *wifi_sta_ip_mac_list);
+
+#ifdef __cplusplus
+}
+#endif

components/esp_wifi/src/wifi_default_ap.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2019-2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2019-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -30,7 +30,17 @@ esp_err_t esp_wifi_ap_get_sta_list_with_ip(const wifi_sta_list_t *wifi_sta_list,
         memcpy(wifi_sta_ip_mac_list->sta[i].mac, wifi_sta_list->sta[i].mac, 6);
         memset(&wifi_sta_ip_mac_list->sta[i].ip, 0, sizeof(esp_ip4_addr_t));
     }
-    return esp_netif_dhcps_get_clients_by_mac(ap, num, wifi_sta_ip_mac_list->sta);
+    esp_err_t err = esp_netif_dhcps_get_clients_by_mac(ap, num, wifi_sta_ip_mac_list->sta);
+    if (err != ESP_OK && err != ESP_ERR_NOT_SUPPORTED) {
+        return err;
+    }
+    for (int i = 0; i < num; i++) {
+        if (wifi_sta_ip_mac_list->sta[i].ip.addr == 0) {
+            // Try to get the IP from the ARP table, and not care about the result
+            esp_netif_arp_get_client_by_mac(ap, &wifi_sta_ip_mac_list->sta[i]);
+        }
+    }
+    return ESP_OK;
 #else
     return ESP_ERR_NOT_SUPPORTED;
 #endif