Merge pull request #9955 from VeijoPesonen/esp8266_wifi_scan_timeout

ESP8266: treats Wi-Fi scan results as out-of-band data; new API to adjusting Wi-Fi scan settings

Author: Cruz Monrreal

components/wifi/esp8266-driver/ESP8266/ESP8266.cpp

@@ -75,6 +75,7 @@ ESP8266::ESP8266(PinName tx, PinName rx, bool debug, PinName rts, PinName cts)
     _parser.oob("ALREADY CONNECTED", callback(this, &ESP8266::_oob_conn_already));
     _parser.oob("ERROR", callback(this, &ESP8266::_oob_err));
     _parser.oob("ready", callback(this, &ESP8266::_oob_ready));
+    _parser.oob("+CWLAP:", callback(this, &ESP8266::_oob_scan_results));
     // Don't expect to find anything about the watchdog reset in official documentation
     //https://techtutorialsx.com/2017/01/21/esp8266-watchdog-functions/
     _parser.oob("wdt reset", callback(this, &ESP8266::_oob_watchdog_reset));
@@ -444,29 +445,28 @@ int8_t ESP8266::rssi()
     return rssi;
 }
 
-int ESP8266::scan(WiFiAccessPoint *res, unsigned limit)
+int ESP8266::scan(WiFiAccessPoint *res, unsigned limit, scan_mode mode, unsigned t_max, unsigned t_min)
 {
-    unsigned cnt = 0;
-    nsapi_wifi_ap_t ap;
-
     _smutex.lock();
-    set_timeout(ESP8266_CONNECT_TIMEOUT);
 
-    if (!_parser.send("AT+CWLAP")) {
-        _smutex.unlock();
-        return NSAPI_ERROR_DEVICE_ERROR;
-    }
+    // Default timeout plus time spend scanning each channel
+    set_timeout(ESP8266_MISC_TIMEOUT + 13 * (t_max ? t_max : ESP8266_SCAN_TIME_MAX_DEFAULT));
 
-    while (_recv_ap(&ap)) {
-        if (cnt < limit) {
-            res[cnt] = WiFiAccessPoint(ap);
-        }
+    _scan_r.res = res;
+    _scan_r.limit = limit;
+    _scan_r.cnt = 0;
 
-        cnt++;
-        if (limit != 0 && cnt >= limit) {
-            break;
+    if (!(_parser.send("AT+CWLAP=,,,%u,%u,%u", (mode == SCANMODE_ACTIVE ? 0 : 1), t_min, t_max) && _parser.recv("OK\n"))) {
+        tr_warning("scan(): AP info parsing aborted");
+        // Lets be happy about partial success and not return NSAPI_ERROR_DEVICE_ERROR
+        if (!_scan_r.cnt) {
+            _scan_r.cnt = NSAPI_ERROR_DEVICE_ERROR;
         }
     }
+
+    int cnt = _scan_r.cnt;
+    _scan_r.res = NULL;
+
     set_timeout();
     _smutex.unlock();
 
@@ -966,38 +966,42 @@ void ESP8266::attach(Callback<void()> status_cb)
 
 bool ESP8266::_recv_ap(nsapi_wifi_ap_t *ap)
 {
-    int sec;
+    int sec = NSAPI_SECURITY_UNKNOWN;
     int dummy;
-    bool ret;
+    int ret;
 
     if (FW_AT_LEAST_VERSION(_at_v.major, _at_v.minor, _at_v.patch, 0, ESP8266_AT_VERSION_WIFI_SCAN_CHANGE)) {
-        ret = _parser.recv("+CWLAP:(%d,\"%32[^\"]\",%hhd,\"%hhx:%hhx:%hhx:%hhx:%hhx:%hhx\",%hhu,%d,%d,%d,%d,%d,%d)\n",
-                           &sec,
-                           ap->ssid,
-                           &ap->rssi,
-                           &ap->bssid[0], &ap->bssid[1], &ap->bssid[2], &ap->bssid[3], &ap->bssid[4], &ap->bssid[5],
-                           &ap->channel,
-                           &dummy,
-                           &dummy,
-                           &dummy,
-                           &dummy,
-                           &dummy,
-                           &dummy);
+        ret = _parser.scanf("(%d,\"%32[^\"]\",%hhd,\"%hhx:%hhx:%hhx:%hhx:%hhx:%hhx\",%hhu,%d,%d,%d,%d,%d,%d)\n",
+                            &sec,
+                            ap->ssid,
+                            &ap->rssi,
+                            &ap->bssid[0], &ap->bssid[1], &ap->bssid[2], &ap->bssid[3], &ap->bssid[4], &ap->bssid[5],
+                            &ap->channel,
+                            &dummy,
+                            &dummy,
+                            &dummy,
+                            &dummy,
+                            &dummy,
+                            &dummy);
     } else {
-        ret = _parser.recv("+CWLAP:(%d,\"%32[^\"]\",%hhd,\"%hhx:%hhx:%hhx:%hhx:%hhx:%hhx\",%hhu,%d,%d)\n",
-                           &sec,
-                           ap->ssid,
-                           &ap->rssi,
-                           &ap->bssid[0], &ap->bssid[1], &ap->bssid[2], &ap->bssid[3], &ap->bssid[4], &ap->bssid[5],
-                           &ap->channel,
-                           &dummy,
-                           &dummy);
+        ret = _parser.scanf("(%d,\"%32[^\"]\",%hhd,\"%hhx:%hhx:%hhx:%hhx:%hhx:%hhx\",%hhu,%d,%d)\n",
+                            &sec,
+                            ap->ssid,
+                            &ap->rssi,
+                            &ap->bssid[0], &ap->bssid[1], &ap->bssid[2], &ap->bssid[3], &ap->bssid[4], &ap->bssid[5],
+                            &ap->channel,
+                            &dummy,
+                            &dummy);
+    }
 
+    if (ret < 0) {
+        _parser.abort();
+        tr_warning("_recv_ap(): AP info missing");
     }
 
     ap->security = sec < 5 ? (nsapi_security_t)sec : NSAPI_SECURITY_UNKNOWN;
 
-    return ret;
+    return ret < 0 ? false : true;
 }
 
 void ESP8266::_oob_watchdog_reset()
@@ -1063,6 +1067,19 @@ void ESP8266::_oob_tcp_data_hdlr()
     _sock_i[_sock_active_id].tcp_data_rcvd = len;
 }
 
+void ESP8266::_oob_scan_results()
+{
+    nsapi_wifi_ap_t ap;
+
+    if (_recv_ap(&ap)) {
+        if (_scan_r.res && _scan_r.cnt < _scan_r.limit) {
+            _scan_r.res[_scan_r.cnt] = WiFiAccessPoint(ap);
+        }
+
+        _scan_r.cnt++;
+    }
+}
+
 void ESP8266::_oob_connect_err()
 {
     _fail = false;

components/wifi/esp8266-driver/ESP8266/ESP8266.h

@@ -44,6 +44,11 @@
 #define ESP8266_MISC_TIMEOUT    2000
 #endif
 
+#define ESP8266_SCAN_TIME_MIN 0     // [ms]
+#define ESP8266_SCAN_TIME_MAX 1500  // [ms]
+#define ESP8266_SCAN_TIME_MIN_DEFAULT 120 // [ms]
+#define ESP8266_SCAN_TIME_MAX_DEFAULT 360 // [ms]
+
 // Firmware version
 #define ESP8266_SDK_VERSION 2000000
 #define ESP8266_SDK_VERSION_MAJOR ESP8266_SDK_VERSION/1000000
@@ -193,14 +198,23 @@ class ESP8266 {
      */
     int8_t rssi();
 
+    /** Scan mode
+     */
+    enum scan_mode {
+        SCANMODE_ACTIVE = 0, /*!< active mode */
+        SCANMODE_PASSIVE = 1 /*!< passive mode */
+    };
+
     /** Scan for available networks
      *
      * @param  ap    Pointer to allocated array to store discovered AP
      * @param  limit Size of allocated @a res array, or 0 to only count available AP
+     * @param  t_max Maximum scan time per channel
+     * @param  t_min Minimum scan time per channel in active mode, can be omitted in passive mode
      * @return       Number of entries in @a res, or if @a count was 0 number of available networks, negative on error
      *               see @a nsapi_error
      */
-    int scan(WiFiAccessPoint *res, unsigned limit);
+    int scan(WiFiAccessPoint *res, unsigned limit, scan_mode mode, unsigned t_max, unsigned t_min);
 
     /**Perform a dns query
     *
@@ -447,6 +461,7 @@ class ESP8266 {
     void _oob_busy();
     void _oob_tcp_data_hdlr();
     void _oob_ready();
+    void _oob_scan_results();
 
     // OOB state variables
     int _connect_error;
@@ -475,6 +490,14 @@ class ESP8266 {
     };
     struct _sock_info _sock_i[SOCKET_COUNT];
 
+    // Scan results
+    struct _scan_results {
+        WiFiAccessPoint *res;
+        unsigned limit;
+        unsigned cnt;
+    };
+    struct _scan_results _scan_r;
+
     // Connection state reporting
     nsapi_connection_status_t _conn_status;
     mbed::Callback<void()> _conn_stat_cb; // ESP8266Interface registered

components/wifi/esp8266-driver/ESP8266Interface.cpp

@@ -371,14 +371,25 @@ int8_t ESP8266Interface::get_rssi()
 
 int ESP8266Interface::scan(WiFiAccessPoint *res, unsigned count)
 {
-    nsapi_error_t status;
+    return scan(res, count, SCANMODE_ACTIVE, 0, 0);
+}
 
-    status = _init();
+int ESP8266Interface::scan(WiFiAccessPoint *res, unsigned count, scan_mode mode, unsigned t_max, unsigned t_min)
+{
+    if (t_max > ESP8266_SCAN_TIME_MAX) {
+        return NSAPI_ERROR_PARAMETER;
+    }
+    if (mode == SCANMODE_ACTIVE && t_min > t_max) {
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    nsapi_error_t status = _init();
     if (status != NSAPI_ERROR_OK) {
         return status;
     }
 
-    return _esp.scan(res, count);
+    return _esp.scan(res, count, (mode == SCANMODE_ACTIVE ? ESP8266::SCANMODE_ACTIVE : ESP8266::SCANMODE_PASSIVE),
+                     t_min, t_max);
 }
 
 bool ESP8266Interface::_get_firmware_ok()

components/wifi/esp8266-driver/ESP8266Interface.h

@@ -157,18 +157,38 @@ class ESP8266Interface : public NetworkStack, public WiFiInterface {
      */
     virtual int8_t get_rssi();
 
+    /** Scan mode
+     */
+    enum scan_mode {
+        SCANMODE_ACTIVE, /*!< active mode */
+        SCANMODE_PASSIVE /*!< passive mode */
+    };
+
     /** Scan for available networks
      *
      * This function will block.
      *
-     * @param  ap       Pointer to allocated array to store discovered AP
-     * @param  count    Size of allocated @a res array, or 0 to only count available AP
-     * @param  timeout  Timeout in milliseconds; 0 for no timeout (Default: 0)
-     * @return          Number of entries in @a, or if @a count was 0 number of available networks, negative on error
-     *                  see @a nsapi_error
+     * @param  ap    Pointer to allocated array to store discovered AP
+     * @param  count Size of allocated @a res array, or 0 to only count available AP
+     * @return       Number of entries in @a, or if @a count was 0 number of available networks, negative on error
+     *               see @a nsapi_error
      */
     virtual int scan(WiFiAccessPoint *res, unsigned count);
 
+    /** Scan for available networks
+     *
+     * This function will block.
+     *
+     * @param  ap    Pointer to allocated array to store discovered AP
+     * @param  count Size of allocated @a res array, or 0 to only count available AP
+     * @param  t_max Scan time for each channel - 0-1500ms. If 0 - uses default value
+     * @param  t_min Minimum for each channel in active mode - 0-1500ms. If 0 - uses default value. Omit in passive mode
+     * @return       Number of entries in @a, or if @a count was 0 number of available networks, negative on error
+     *               see @a nsapi_error
+     */
+    virtual int scan(WiFiAccessPoint *res, unsigned count, scan_mode mode = SCANMODE_PASSIVE,
+                     unsigned t_max = 0, unsigned t_min = 0);
+
     /** Translates a hostname to an IP address with specific version
      *
      *  The hostname may be either a domain name or an IP address. If the