add support for list of AP connections

- auto select ssid with best signal
 - for debugging enable DEBUG_WIFI_MULTI macro and call Serial.setDebugOutput(true);

change ESP8266WiFiClass::status() return type to wl_status_t

libraries/ESP8266WiFi/src/ESP8266WiFiMulti.cpp

@@ -0,0 +1,167 @@
+/**
+ *
+ * @file ESP8266WiFiMulti.cpp
+ * @date 16.05.2015
+ * @author Markus Sattler
+ *
+ * Copyright (c) 2015 Markus Sattler. All rights reserved.
+ * This file is part of the esp8266 core for Arduino environment.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#include "ESP8266WiFi.h"
+#include "ESP8266WiFiMulti.h"
+#include <limits.h>
+
+ESP8266WiFiMulti::ESP8266WiFiMulti() {
+}
+
+ESP8266WiFiMulti::~ESP8266WiFiMulti() {
+    APlistClean();
+}
+
+bool ESP8266WiFiMulti::addAP(const char* ssid, const char *passphrase) {
+    return APlistAdd(ssid, passphrase);
+}
+
+wl_status_t ESP8266WiFiMulti::run(void) {
+
+    wl_status_t status = WiFi.status();
+    if(status == WL_DISCONNECTED || status == WL_NO_SSID_AVAIL || status == WL_IDLE_STATUS || status == WL_CONNECT_FAILED) {
+
+        WifiAPlist_t bestNetwork { NULL, NULL };
+        int bestNetworkDb = INT_MIN;
+
+        // WiFi.scanNetworks will return the number of networks found
+        int8_t n = WiFi.scanNetworks();
+
+        DEBUG_WIFI_MULTI("[WIFI] scan done\n");
+        delay(0);
+
+        if(n <= 0) {
+            DEBUG_WIFI_MULTI("[WIFI] no networks found\n");
+        } else {
+            DEBUG_WIFI_MULTI("[WIFI] %d networks found\n", n);
+            for(int8_t i = 0; i < n; ++i) {
+                const char * ssid_scan = WiFi.SSID(i);
+                int32_t rssi_scan = WiFi.RSSI(i);
+                uint8_t sec_scan = WiFi.encryptionType(i);
+
+                bool known = false;
+                for(uint32_t x = 0; x < APlist.size(); x++) {
+                    WifiAPlist_t entry = APlist[x];
+
+                    if(strcmp(entry.ssid, ssid_scan) == 0) { // SSID match
+                        known = true;
+                        if(rssi_scan > bestNetworkDb) { // best network
+                            if(sec_scan == ENC_TYPE_NONE || entry.passphrase) { // check for passphrase if not open wlan
+                                bestNetworkDb = rssi_scan;
+                                memcpy((void*) &bestNetwork, (void*) &entry, sizeof(bestNetwork));
+                            }
+                        }
+                        break;
+                    }
+                }
+                if(known) {
+                    DEBUG_WIFI_MULTI(" ---> ");
+                } else {
+                    DEBUG_WIFI_MULTI("      ");
+                }
+
+                DEBUG_WIFI_MULTI(" %d: %s (%d) %c\n", i, ssid_scan, rssi_scan, (sec_scan == ENC_TYPE_NONE) ? ' ' : '*');
+                delay(0);
+            }
+        }
+
+        DEBUG_WIFI_MULTI("\n\n");
+        delay(0);
+
+        if(bestNetwork.ssid) {
+            DEBUG_WIFI_MULTI("[WIFI] Connecting SSID: %s (%d)\n", bestNetwork.ssid, bestNetworkDb);
+
+            WiFi.begin(bestNetwork.ssid, bestNetwork.passphrase);
+            status = WiFi.status();
+
+            // wait for connection or fail
+            while(status != WL_CONNECTED && status != WL_NO_SSID_AVAIL && status != WL_CONNECT_FAILED) {
+                delay(10);
+                status = WiFi.status();
+            }
+
+            switch(status) {
+                case WL_CONNECTED:
+                    DEBUG_WIFI_MULTI("[WIFI] Connecting Done.\n");
+                    break;
+                case WL_NO_SSID_AVAIL:
+                    DEBUG_WIFI_MULTI("[WIFI] Connecting Faild AP not found.\n");
+                    break;
+                case WL_CONNECT_FAILED:
+                    DEBUG_WIFI_MULTI("[WIFI] Connecting Faild.\n");
+                    break;
+                default:
+                    DEBUG_WIFI_MULTI("[WIFI] Connecting Faild (%d).\n", status);
+                    break;
+            }
+        } else {
+            DEBUG_WIFI_MULTI("[WIFI] no matching wifi found!\n");
+        }
+    }
+    return status;
+}
+
+// ##################################################################################
+
+bool ESP8266WiFiMulti::APlistAdd(const char* ssid, const char *passphrase) {
+
+    WifiAPlist_t newAP;
+
+    newAP.ssid = (char*) malloc(strlen(ssid));
+
+    if(!newAP.ssid) {
+        return false;
+    }
+
+    strcpy(newAP.ssid, ssid);
+
+    if(passphrase && *passphrase != 0x00) {
+        newAP.passphrase = (char*) malloc(strlen(passphrase));
+    }
+
+    if(!newAP.passphrase) {
+        free(newAP.ssid);
+        return false;
+    }
+
+    strcpy(newAP.passphrase, passphrase);
+
+    APlist.push_back(newAP);
+    return true;
+}
+
+void ESP8266WiFiMulti::APlistClean(void) {
+    for(uint32_t i = 0; i < APlist.size(); i++) {
+        WifiAPlist_t entry = APlist[i];
+        if(entry.ssid) {
+            free(entry.ssid);
+        }
+        if(entry.passphrase) {
+            free(entry.passphrase);
+        }
+    }
+    APlist.clear();
+}
+