Bound Wi-Fi scan results to fixed storage

components/connect/connect.c

@@ -22,9 +22,6 @@
 #include "nvs_config.h"
 #include "esp_app_desc.h"
 
-// Maximum number of access points to scan
-#define MAX_AP_COUNT 20
-
 #if CONFIG_ESP_WPA3_SAE_PWE_HUNT_AND_PECK
 #define ESP_WIFI_SAE_MODE WPA3_SAE_PWE_HUNT_AND_PECK
 #define EXAMPLE_H2E_IDENTIFIER ""
@@ -62,7 +59,7 @@ static TimerHandle_t ip_acquire_timer = NULL;
 
 static bool is_scanning = false;
 static uint16_t ap_number = 0;
-static wifi_ap_record_t ap_info[MAX_AP_COUNT];
+static wifi_ap_record_t ap_info[WIFI_SCAN_MAX_AP_COUNT];
 static int s_retry_num = 0;
 static int clients_connected_to_ap = 0;
 static bool mdns_initialized = false;
@@ -316,15 +313,22 @@ esp_err_t get_wifi_current_rssi(int8_t *rssi)
 }
 
 // Function to scan for available WiFi networks
-esp_err_t wifi_scan(wifi_ap_record_simple_t *ap_records, uint16_t *ap_count)
+esp_err_t wifi_scan(wifi_ap_record_simple_t *ap_records, size_t records_capacity, uint16_t *ap_count)
 {
+    if (ap_records == NULL || ap_count == NULL || records_capacity == 0) {
+        return ESP_ERR_INVALID_ARG;
+    }
+
+    *ap_count = 0;
+
     if (is_scanning) {
         ESP_LOGW(TAG, "Scan already in progress");
         return ESP_ERR_INVALID_STATE;
     }
 
     ESP_LOGI(TAG, "Starting Wi-Fi scan!");
     is_scanning = true;
+    ap_number = 0;
 
     wifi_ap_record_t current_ap_info;
     if (esp_wifi_sta_get_ap_info(&current_ap_info) != ESP_OK) {
@@ -352,6 +356,7 @@ esp_err_t wifi_scan(wifi_ap_record_simple_t *ap_records, uint16_t *ap_count)
         retries_remaining--;
         if (retries_remaining == 0) {
             is_scanning = false;
+            ap_number = 0;
             return ESP_FAIL;
         }
         vTaskDelay(1000 / portTICK_PERIOD_MS);
@@ -362,10 +367,19 @@ esp_err_t wifi_scan(wifi_ap_record_simple_t *ap_records, uint16_t *ap_count)
         ESP_LOGW(TAG, "No Wi-Fi networks found");
     }
 
-    *ap_count = ap_number;
-    memset(ap_records, 0, (*ap_count) * sizeof(wifi_ap_record_simple_t));
-    for (int i = 0; i < ap_number; i++) {
+    size_t records_to_copy = ap_number;
+    if (records_to_copy > WIFI_SCAN_MAX_AP_COUNT) {
+        records_to_copy = WIFI_SCAN_MAX_AP_COUNT;
+    }
+    if (records_to_copy > records_capacity) {
+        records_to_copy = records_capacity;
+    }
+
+    *ap_count = (uint16_t)records_to_copy;
+    memset(ap_records, 0, records_to_copy * sizeof(*ap_records));
+    for (size_t i = 0; i < records_to_copy; i++) {
         memcpy(ap_records[i].ssid, ap_info[i].ssid, sizeof(ap_records[i].ssid));
+        ap_records[i].ssid[sizeof(ap_records[i].ssid) - 1U] = '\0';
         ap_records[i].rssi = ap_info[i].rssi;
         ap_records[i].authmode = ap_info[i].authmode;
     }
@@ -391,10 +405,26 @@ static void event_handler(void * arg, esp_event_base_t event_base, int32_t event
     if (event_base == WIFI_EVENT)
     {
         if (event_id == WIFI_EVENT_SCAN_DONE) {
-            esp_wifi_scan_get_ap_num(&ap_number);
-            ESP_LOGI(TAG, "Wi-Fi Scan Done");
-            if (esp_wifi_scan_get_ap_records(&ap_number, ap_info) != ESP_OK) {
-                ESP_LOGI(TAG, "Failed esp_wifi_scan_get_ap_records");
+            uint16_t total_found = 0;
+            uint16_t records_capacity =
+                (uint16_t)(sizeof(ap_info) / sizeof(ap_info[0]));
+
+            esp_err_t scan_err = esp_wifi_scan_get_ap_num(&total_found);
+            if (scan_err != ESP_OK) {
+                ESP_LOGW(TAG, "Failed to get Wi-Fi scan count: %s", esp_err_to_name(scan_err));
+                ap_number = 0;
+            } else {
+                ESP_LOGI(TAG, "Wi-Fi Scan Done: %u network(s) found", total_found);
+                scan_err = esp_wifi_scan_get_ap_records(&records_capacity, ap_info);
+                if (scan_err != ESP_OK) {
+                    ESP_LOGW(TAG, "Failed to get Wi-Fi scan records: %s", esp_err_to_name(scan_err));
+                    ap_number = 0;
+                } else {
+                    if (records_capacity > WIFI_SCAN_MAX_AP_COUNT) {
+                        records_capacity = WIFI_SCAN_MAX_AP_COUNT;
+                    }
+                    ap_number = records_capacity;
+                }
             }
             is_scanning = false;
         }

components/connect/include/connect.h

@@ -5,12 +5,15 @@
 #include <arpa/inet.h>
 #include <lwip/netdb.h>
 #include <stdbool.h>
+#include <stddef.h>
 
 #include "esp_err.h"
 #include "esp_wifi_types.h"
 
 typedef struct GlobalState GlobalState;
 
+#define WIFI_SCAN_MAX_AP_COUNT 20U
+
 // Structure to hold WiFi scan results
 typedef struct {
     char ssid[33];  // 32 chars + null terminator
@@ -21,7 +24,7 @@ typedef struct {
 void toggle_wifi_softap(void);
 void wifi_init(GlobalState * GLOBAL_STATE);
 esp_err_t wifi_apply_hostname(const char *hostname);
-esp_err_t wifi_scan(wifi_ap_record_simple_t *ap_records, uint16_t *ap_count);
+esp_err_t wifi_scan(wifi_ap_record_simple_t *ap_records, size_t records_capacity, uint16_t *ap_count);
 esp_err_t get_wifi_current_rssi(int8_t *rssi);
 bool wifi_is_connected(void);
 esp_err_t update_mdns_hostname(const char *new_hostname, GlobalState *GLOBAL_STATE);

main/http_server/http_server.c

@@ -180,10 +180,10 @@ static esp_err_t GET_wifi_scan(httpd_req_t *req)
     // Give some time for the connected flag to take effect
     vTaskDelay(100 / portTICK_PERIOD_MS);
 
-    wifi_ap_record_simple_t ap_records[20];
+    wifi_ap_record_simple_t ap_records[WIFI_SCAN_MAX_AP_COUNT];
     uint16_t ap_count = 0;
 
-    esp_err_t err = wifi_scan(ap_records, &ap_count);
+    esp_err_t err = wifi_scan(ap_records, sizeof(ap_records) / sizeof(ap_records[0]), &ap_count);
     if (err != ESP_OK) {
         httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, "WiFi scan failed");
         return ESP_OK;