Feature: support connecting to a fixed Wi-Fi BSSID

Author: schlimmchen

include/Configuration.h

@@ -15,6 +15,7 @@
 #define WIFI_MAX_SSID_STRLEN 32
 #define WIFI_MAX_PASSWORD_STRLEN 64
 #define WIFI_MAX_HOSTNAME_STRLEN 31
+#define WIFI_BSSID_OCTETS 6
 
 #define SYSLOG_MAX_HOSTNAME_STRLEN 128
 
@@ -318,6 +319,7 @@ struct CONFIG_T {
     struct {
         char Ssid[WIFI_MAX_SSID_STRLEN + 1];
         char Password[WIFI_MAX_PASSWORD_STRLEN + 1];
+        uint8_t Bssid[WIFI_BSSID_OCTETS];
         uint8_t Ip[4];
         uint8_t Netmask[4];
         uint8_t Gateway[4];
@@ -471,6 +473,8 @@ class ConfigurationClass {
     INVERTER_CONFIG_T* getFreeInverterSlot();
     INVERTER_CONFIG_T* getInverterConfig(const uint64_t serial);
     void deleteInverterById(const uint8_t id);
+    static String serializeBssid(uint8_t const* bssid);
+    static void deserializeBssid(String const& bssidStr, uint8_t* bssid);
 
     int8_t getIndexForLogModule(const String& moduleName) const;
 

include/defaults.h

@@ -18,6 +18,7 @@
 
 #define WIFI_SSID ""
 #define WIFI_PASSWORD ""
+#define WIFI_BSSID ""
 #define WIFI_DHCP true
 
 #define MDNS_ENABLED false

src/Configuration.cpp

@@ -276,6 +276,7 @@ bool ConfigurationClass::write()
     JsonObject wifi = doc["wifi"].to<JsonObject>();
     wifi["ssid"] = config.WiFi.Ssid;
     wifi["password"] = config.WiFi.Password;
+    wifi["bssid"] = serializeBssid(config.WiFi.Bssid);
     wifi["ip"] = IPAddress(config.WiFi.Ip).toString();
     wifi["netmask"] = IPAddress(config.WiFi.Netmask).toString();
     wifi["gateway"] = IPAddress(config.WiFi.Gateway).toString();
@@ -710,6 +711,7 @@ bool ConfigurationClass::read()
     JsonObject wifi = doc["wifi"];
     strlcpy(config.WiFi.Ssid, wifi["ssid"] | WIFI_SSID, sizeof(config.WiFi.Ssid));
     strlcpy(config.WiFi.Password, wifi["password"] | WIFI_PASSWORD, sizeof(config.WiFi.Password));
+    deserializeBssid(wifi["bssid"] | WIFI_BSSID, config.WiFi.Bssid);
     strlcpy(config.WiFi.Hostname, wifi["hostname"] | APP_HOSTNAME, sizeof(config.WiFi.Hostname));
 
     IPAddress wifi_ip;
@@ -1257,6 +1259,41 @@ int8_t ConfigurationClass::getIndexForLogModule(const String& moduleName) const
     return -1;
 }
 
+String ConfigurationClass::serializeBssid(uint8_t const* bssid)
+{
+    if (std::all_of(bssid, bssid + WIFI_BSSID_OCTETS, [](uint8_t b) { return b == 0; })) {
+        return "";
+    }
+
+    // 2 chars per byte + one separator between bytes + null terminator
+    char bssidStr[WIFI_BSSID_OCTETS * 2 + WIFI_BSSID_OCTETS - 1 + 1];
+    snprintf(bssidStr, sizeof(bssidStr), "%02X:%02X:%02X:%02X:%02X:%02X",
+        bssid[0], bssid[1], bssid[2], bssid[3], bssid[4], bssid[5]);
+    return bssidStr;
+}
+
+void ConfigurationClass::deserializeBssid(String const& bssidStr, uint8_t* bssid)
+{
+    memset(bssid, 0, WIFI_BSSID_OCTETS);
+
+    String cleanBssidStr = bssidStr;
+    cleanBssidStr.replace(":", "");
+    cleanBssidStr.replace("-", "");
+
+    if (cleanBssidStr.length() != 12) { return; }
+
+    for (int i = 0; i < WIFI_BSSID_OCTETS; i++) {
+        char byteStr[3] = {cleanBssidStr[i*2], cleanBssidStr[i*2+1], 0};
+        char* endPtr;
+        bssid[i] = strtol(byteStr, &endPtr, 16);
+        if (endPtr != byteStr + 2) {
+            // invalid hex value in BSSID string
+            memset(bssid, 0, WIFI_BSSID_OCTETS);
+            return;
+        }
+    }
+}
+
 void ConfigurationClass::loop()
 {
     std::unique_lock<std::mutex> lock(sWriterMutex);

src/NetworkSettings.cpp

@@ -321,7 +321,33 @@ void NetworkSettingsClass::applyConfig()
         return;
     }
 
-    const bool newCredentials = strcmp(WiFi.SSID().c_str(), config.Ssid) || strcmp(WiFi.psk().c_str(), config.Password);
+    uint8_t const* configuredBssid = NULL; // auto
+    if (std::any_of(std::begin(Configuration.get().WiFi.Bssid),
+                    std::end(Configuration.get().WiFi.Bssid),
+                    [](uint8_t b) { return b != 0; })) {
+        configuredBssid = Configuration.get().WiFi.Bssid;
+    }
+
+    auto bssidChanged = [configuredBssid]() -> bool {
+        uint8_t* currentBssid = WiFi.BSSID();
+        if (configuredBssid == NULL && currentBssid == NULL) {
+            return false;
+        }
+
+        if (configuredBssid == NULL || currentBssid == NULL) {
+            return true;
+        }
+
+        for (int i = 0; i < WIFI_BSSID_OCTETS; i++) {
+            if (configuredBssid[i] != currentBssid[i]) {
+                return true;
+            }
+        }
+
+        return false;
+    };
+
+    const bool newCredentials = strcmp(WiFi.SSID().c_str(), config.Ssid) || strcmp(WiFi.psk().c_str(), config.Password) || bssidChanged();
 
     ESP_LOGI(TAG, "Start configuring WiFi STA using %s credentials",
         newCredentials ? "new" : "existing");
@@ -330,7 +356,9 @@ void NetworkSettingsClass::applyConfig()
     if (newCredentials) {
         success = WiFi.begin(
             config.Ssid,
-            config.Password) != WL_CONNECT_FAILED;
+            config.Password,
+            0, // channel (0 = auto)
+            configuredBssid) != WL_CONNECT_FAILED;
     } else {
         success = WiFi.begin() != WL_CONNECT_FAILED;
     }

src/WebApi_network.cpp

@@ -75,6 +75,7 @@ void WebApiNetworkClass::onNetworkAdminGet(AsyncWebServerRequest* request)
     root["dns2"] = IPAddress(config.WiFi.Dns2).toString();
     root["ssid"] = config.WiFi.Ssid;
     root["password"] = config.WiFi.Password;
+    root["bssid"] = Configuration.serializeBssid(config.WiFi.Bssid);
     root["aptimeout"] = config.WiFi.ApTimeout;
     root["mdnsenabled"] = config.Mdns.Enabled;
     root["syslogenabled"] = config.Syslog.Enabled;
@@ -100,6 +101,7 @@ void WebApiNetworkClass::onNetworkAdminPost(AsyncWebServerRequest* request)
 
     if (!(root["ssid"].is<String>()
             && root["password"].is<String>()
+            && root["bssid"].is<String>()
             && root["hostname"].is<String>()
             && root["dhcp"].is<bool>()
             && root["ipaddress"].is<String>()
@@ -216,6 +218,7 @@ void WebApiNetworkClass::onNetworkAdminPost(AsyncWebServerRequest* request)
         config.WiFi.Dns2[3] = dns2[3];
         strlcpy(config.WiFi.Ssid, root["ssid"].as<String>().c_str(), sizeof(config.WiFi.Ssid));
         strlcpy(config.WiFi.Password, root["password"].as<String>().c_str(), sizeof(config.WiFi.Password));
+        Configuration.deserializeBssid(root["bssid"].as<String>(), config.WiFi.Bssid);
         strlcpy(config.WiFi.Hostname, root["hostname"].as<String>().c_str(), sizeof(config.WiFi.Hostname));
         if (root["dhcp"].as<bool>()) {
             config.WiFi.Dhcp = true;

webapp/src/locales/de.json

@@ -544,6 +544,8 @@
         "WifiConfiguration": "WLAN-Konfiguration",
         "WifiSsid": "WLAN-SSID",
         "WifiPassword": "WLAN-Passwort",
+        "WifiBssid": "WLAN-BSSID",
+        "WifiBssidHint": "Setze die BSSID des WLAN-Access Points, um mit einem bestimmten Access Point zu verbinden. Leer lassen um jeden Access Point zu erlauben.",
         "Hostname": "Hostname",
         "HostnameHint": "<b>Hinweis:</b> Der Text <span class=\"font-monospace\">%06X</span> wird durch die letzten 6 Ziffern der ESP-ChipID im Hex-Format ersetzt.",
         "EnableDhcp": "DHCP aktivieren",

webapp/src/locales/en.json

@@ -544,6 +544,8 @@
         "WifiConfiguration": "WiFi Configuration",
         "WifiSsid": "WiFi SSID",
         "WifiPassword": "WiFi Password",
+        "WifiBssid": "WiFi BSSID",
+        "WifiBssidHint": "Set the BSSID of the WiFi Access Point to connect to. Leave empty to allow connecting to any Access Point.",
         "Hostname": "Hostname",
         "HostnameHint": "<b>Hint:</b> The text <span class=\"font-monospace\">%06X</span> will be replaced with the last 6 digits of the ESP ChipID in hex format.",
         "EnableDhcp": "Enable DHCP",

webapp/src/types/NetworkConfig.ts

@@ -1,6 +1,7 @@
 export interface NetworkConfig {
     ssid: string;
     password: string;
+    bssid: string;
     hostname: string;
     dhcp: boolean;
     ipaddress: string;

webapp/src/views/NetworkAdminView.vue

@@ -25,6 +25,15 @@
                     maxlength="64"
                 />
 
+                <InputElement
+                    :label="$t('networkadmin.WifiBssid')"
+                    :tooltip="$t('networkadmin.WifiBssidHint')"
+                    v-model="networkConfigList.bssid"
+                    type="text"
+                    minlength="12"
+                    maxlength="17"
+                />
+
                 <InputElement
                     :label="$t('networkadmin.Hostname')"
                     v-model="networkConfigList.hostname"