Finish basic scanning routines.

main/include/wifi_connection.h

@@ -5,7 +5,32 @@
 
 #include "esp_wifi.h"
 
+// Simpler interpretation of WiFi signal strength.
+typedef enum {
+	WIFI_STRENGTH_VERY_BAD,
+	WIFI_STRENGTH_BAD,
+	WIFI_STRENGTH_GOOD,
+	WIFI_STRENGTH_VERY_GOOD,
+} wifi_strength_t;
+
+// Thresholds for aforementioned signal strength definitions.
+#define WIFI_THRESH_BAD       -80
+#define WIFI_THRESH_GOOD      -70
+#define WIFI_THRESH_VERY_GOOD -67
+
+// Firt time initialisation of the WiFi stack.
 void wifi_init();
+
+// Connect to a traditional username/password WiFi network.
 bool wifi_connect(const char* aSsid, const char* aPassword, wifi_auth_mode_t aAuthmode, uint8_t aRetryMax);
+
+// Connect to a WPA2 enterprise WiFi network.
 bool wifi_connect_ent(const char* aSsid, const char *aIdent, const char *aAnonIdent, const char* aPassword, uint8_t aRetryMax);
-void wifi_scan();
+
+// Scan for WiFi networks.
+// Updates the APs pointer if non-null.
+// Returns the number of APs found.
+size_t wifi_scan(wifi_ap_record_t **aps);
+
+// Get the strength value for a given RSSI.
+wifi_strength_t wifi_rssi_to_strength(int8_t rssi);

main/main.c

@@ -306,10 +306,6 @@ void display_fatal_error(pax_buf_t* pax_buffer, ILI9341* ili9341, const char* li
     ili9341_write(ili9341, pax_buffer->buf);
 }
 
-// void wifi_connect_to_stored() {
-//     wifi_connect_ent("MCH2022-legacy", "thefunny", "q", "nope, you are not", 3);
-// }
-
 void wifi_connect_to_stored() {
     // Open NVS.
     nvs_handle_t handle;
@@ -893,6 +889,9 @@ void app_main(void) {
                     char buffer[300];
                     snprintf(buffer, sizeof(buffer), "SSID is %s\nPassword is %s", ssid, password);
                     graphics_task(pax_buffer, ili9341, NULL, buffer);
+                } else if (menu_action == ACTION_WIFI_SCAN) {
+                    // Scan for WiFi networks.
+                    wifi_scan(NULL);
                 } else {
                     break;
                 }

main/wifi_connection.c

@@ -16,35 +16,47 @@ static const char *TAG = "wifi_connection";
 
 #define WIFI_CONNECTED_BIT BIT0
 #define WIFI_FAIL_BIT      BIT1
+#define WIFI_STARTED_BIT   BIT2
 
-static EventGroupHandle_t s_wifi_event_group;
+static EventGroupHandle_t wifiEventGroup;
 
-static uint8_t gRetryCounter = 0;
+static uint8_t retryCount = 0;
-static uint8_t gRetryMax = 3;
+static uint8_t maxRetries = 3;
+static bool isScanning = false;
 
 static void event_handler(void* arg, esp_event_base_t event_base, int32_t event_id, void* event_data) {
     if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
+        xEventGroupSetBits(wifiEventGroup, WIFI_STARTED_BIT);
+        if (!isScanning) {
+            // Connect only if we're not scanning the WiFi.
             esp_wifi_connect();
+        }
+        ESP_LOGI(TAG, "WiFi station start.");
+    } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_STOP) {
+        xEventGroupClearBits(wifiEventGroup, WIFI_STARTED_BIT);
+        ESP_LOGI(TAG, "WiFi station stop.");
     } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
-        if (gRetryCounter < 3) {
+        if (retryCount < 3) {
             esp_wifi_connect();
-            gRetryCounter++;
+            retryCount++;
-            ESP_LOGI(TAG, "retry to connect to the AP");
+            ESP_LOGI(TAG, "Retrying connection");
         } else {
-            ESP_LOGI(TAG,"connect to the AP fail");
+            ESP_LOGI(TAG, "Connection failed");
-            xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT);
+            xEventGroupSetBits(wifiEventGroup, WIFI_FAIL_BIT);
         }
     } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
         ip_event_got_ip_t* event = (ip_event_got_ip_t*) event_data;
-        ESP_LOGI(TAG, "got ip:" IPSTR, IP2STR(&event->ip_info.ip));
+        ESP_LOGI(TAG, "Got ip:" IPSTR, IP2STR(&event->ip_info.ip));
-        gRetryCounter = 0;
+        retryCount = 0;
-        xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
+        xEventGroupSetBits(wifiEventGroup, WIFI_CONNECTED_BIT);
     }
 }
 
 void wifi_init() {
-    s_wifi_event_group = xEventGroupCreate();
+    // Create an event group for WiFi things.
+    wifiEventGroup = xEventGroupCreate();
     
+    // Initialise WiFi stack.
     ESP_ERROR_CHECK(esp_netif_init());
     
     ESP_ERROR_CHECK(esp_event_loop_create_default());
@@ -53,17 +65,22 @@ void wifi_init() {
     wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
     ESP_ERROR_CHECK(esp_wifi_init(&cfg));
     
+    // Register event handlers for WiFi.
     esp_event_handler_instance_t instance_any_id;
     esp_event_handler_instance_t instance_got_ip;
     ESP_ERROR_CHECK(esp_event_handler_instance_register(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL, &instance_any_id));
     ESP_ERROR_CHECK(esp_event_handler_instance_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL, &instance_got_ip));
     
+    // Turn off WiFi hardware.
     ESP_ERROR_CHECK(esp_wifi_stop());
 }
 
 bool wifi_connect(const char* aSsid, const char* aPassword, wifi_auth_mode_t aAuthmode, uint8_t aRetryMax) {
-    gRetryCounter = 0;
+    // Set the retry counts.
-    gRetryMax = aRetryMax;
+    retryCount = 0;
+    maxRetries = aRetryMax;
+    
+    // Create a config.
     wifi_config_t wifi_config = {0};
     strcpy((char*) wifi_config.sta.ssid, aSsid);
     strcpy((char*) wifi_config.sta.password, aPassword);
@@ -81,7 +98,7 @@ bool wifi_connect(const char* aSsid, const char* aPassword, wifi_auth_mode_t aAu
     
     /* Waiting until either the connection is established (WIFI_CONNECTED_BIT) or connection failed for the maximum
      * number of re-tries (WIFI_FAIL_BIT). The bits are set by event_handler() (see above) */
-    EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group, WIFI_CONNECTED_BIT | WIFI_FAIL_BIT, pdFALSE, pdFALSE, portMAX_DELAY);
+    EventBits_t bits = xEventGroupWaitBits(wifiEventGroup, WIFI_CONNECTED_BIT | WIFI_FAIL_BIT, pdFALSE, pdFALSE, portMAX_DELAY);
     /* xEventGroupWaitBits() returns the bits before the call returned, hence we can test which event actually happened. */
     if (bits & WIFI_CONNECTED_BIT) {
         ESP_LOGI(TAG, "Connected to WiFi");
@@ -97,8 +114,8 @@ bool wifi_connect(const char* aSsid, const char* aPassword, wifi_auth_mode_t aAu
 }
 
 bool wifi_connect_ent(const char* aSsid, const char *aIdent, const char *aAnonIdent, const char* aPassword, uint8_t aRetryMax) {
-    gRetryCounter = 0;
+    retryCount = 0;
-    gRetryMax = aRetryMax;
+    maxRetries = aRetryMax;
     wifi_config_t wifi_config = {0};
     if (strlen(aSsid) > 32) {
         ESP_LOGE(TAG, "SSID is too long (%zu > 32)!", strlen(aSsid));
@@ -126,7 +143,7 @@ bool wifi_connect_ent(const char* aSsid, const char *aIdent, const char *aAnonId
     
     /* Waiting until either the connection is established (WIFI_CONNECTED_BIT) or connection failed for the maximum
      * number of re-tries (WIFI_FAIL_BIT). The bits are set by event_handler() (see above) */
-    EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group, WIFI_CONNECTED_BIT | WIFI_FAIL_BIT, pdFALSE, pdFALSE, portMAX_DELAY);
+    EventBits_t bits = xEventGroupWaitBits(wifiEventGroup, WIFI_CONNECTED_BIT | WIFI_FAIL_BIT, pdFALSE, pdFALSE, portMAX_DELAY);
     /* xEventGroupWaitBits() returns the bits before the call returned, hence we can test which event actually happened. */
     if (bits & WIFI_CONNECTED_BIT) {
         ESP_LOGI(TAG, "Connected to WiFi");
@@ -141,6 +158,116 @@ bool wifi_connect_ent(const char* aSsid, const char *aIdent, const char *aAnonId
     return false;
 }
 
-void wifi_scan() {
+// Shows a nice info message describing an AP record.
+static inline void wifi_desc_record(wifi_ap_record_t *record) {
+    // Make a string representation of BSSID.
+    char *bssid_str = malloc(3*6);
+    if (!bssid_str) return;
+    snprintf(bssid_str, 3*6, "%02X:%02X:%02X:%02X:%02X:%02X",
+        record->bssid[0], record->bssid[1], record->bssid[2],
+        record->bssid[3], record->bssid[4], record->bssid[5]
+    );
     
+    // Make a string representation of 11b/g/n modes.
+    char *phy_str = malloc(9);
+    if (!phy_str) {
+        free(bssid_str);
+        return;
+    }
+    *phy_str = 0;
+    if (record->phy_11b | record->phy_11g | record->phy_11n) {
+        strcpy(phy_str, " 1");
+    }
+    if (record->phy_11b) {
+        strcat(phy_str, "/b");
+    }
+    if (record->phy_11g) {
+        strcat(phy_str, "/g");
+    }
+    if (record->phy_11n) {
+        strcat(phy_str, "/n");
+    }
+    phy_str[2] = '1';
+    
+    ESP_LOGI(TAG, "AP %s %s rssi=%hhd%s", bssid_str, record->ssid, record->rssi, phy_str);
+    free(bssid_str);
+    free(phy_str);
+}
+
+// Scan for WiFi access points.
+size_t wifi_scan(wifi_ap_record_t **aps_out) {
+    isScanning = true;
+    // Scan for any non-hidden APs on all channels.
+    wifi_scan_config_t cfg = {
+        .ssid    = NULL,
+        .bssid   = NULL,
+        .channel = 0,
+        .scan_type = WIFI_SCAN_TYPE_ACTIVE,
+        .scan_time = { .active={ 0, 0 } },
+    };
+    
+    // Start the scan now.
+    ESP_LOGI(TAG, "Starting scan...");
+    esp_err_t res = esp_wifi_scan_start(&cfg, true);
+    // Whether to call esp_wifi_stop() on finish.
+    bool stopWhenDone = false;
+    if (res == ESP_ERR_WIFI_NOT_STARTED) {
+        // If it complains that the wifi wasn't started, then do so.
+        ESP_LOGI(TAG, "Starting WiFi for scan");
+        
+        // Set to station but don't connect.
+        res = esp_wifi_set_mode(WIFI_MODE_STA);
+        if (res) goto ohno;
+        
+        // Start WiFi.
+        res = esp_wifi_start();
+        if (res) goto ohno;
+        stopWhenDone = true;
+        
+        // Await the STA started bit.
+        xEventGroupWaitBits(wifiEventGroup, WIFI_STARTED_BIT, pdFALSE, pdFALSE, pdMS_TO_TICKS(2000));
+        
+        // Try again.
+        res = esp_wifi_scan_start(&cfg, true);
+    }
+    if (res) {
+        ohno:
+        ESP_LOGE(TAG, "Error in WiFi scan: %s", esp_err_to_name(res));
+        isScanning = false;
+        return 0;
+    }
+    
+    // Allocate memory for AP list.
+    uint16_t num_ap = 0;
+    esp_wifi_scan_get_ap_num(&num_ap);
+    wifi_ap_record_t *aps = malloc(sizeof(wifi_ap_record_t) * num_ap);
+    
+    // Collect APs and report findings.
+    esp_wifi_scan_get_ap_records(&num_ap, aps);
+    for (uint16_t i = 0; i < num_ap; i++) {
+        wifi_desc_record(&aps[i]);
+    }
+    
+    // Clean up.
+    if (aps_out) {
+        // Output pointer is non-null, return the APs list.
+        *aps_out = aps;
+    } else {
+        // Output pointer is null, free the APs list.
+        free(aps);
+    }
+    if (stopWhenDone) {
+        // Stop WiFi because it was started only for this scan.
+        esp_wifi_stop();
+    }
+    isScanning = false;
+    return num_ap;
+}
+
+// Get the strength value for a given RSSI.
+wifi_strength_t wifi_rssi_to_strength(int8_t rssi) {
+    if (rssi > WIFI_THRESH_VERY_GOOD) return WIFI_STRENGTH_VERY_GOOD;
+    else if (rssi > WIFI_THRESH_GOOD) return WIFI_STRENGTH_GOOD;
+    else if (rssi > WIFI_THRESH_BAD)  return WIFI_STRENGTH_BAD;
+    else return WIFI_STRENGTH_VERY_BAD;
 }