add example for WiFiClientSecure PSK

Author: tve

libraries/WiFiClientSecure/examples/WiFiClientPSK/WiFiClientPSK.ino

@@ -0,0 +1,85 @@
+/*
+  Wifi secure connection example for ESP32 using a pre-shared key (PSK)
+  This is useful with MQTT servers instead of using a self-signed cert, tested with mosquitto.
+  Running on TLS 1.2 using mbedTLS
+
+  To test run a test server using: openssl s_server -accept 8443 -psk 1a2b3c4d -nocert
+  It will show the http request made, but there's no easy way to send a reply back...
+
+  2017 - Evandro Copercini - Apache 2.0 License.
+  2018 - Adapted for PSK by Thorsten von Eicken
+*/
+
+#include <WiFiClientSecure.h>
+
+#if 0
+const char* ssid     = "your-ssid";     // your network SSID (name of wifi network)
+const char* password = "your-password"; // your network password
+#else
+const char* ssid     = "test";     // your network SSID (name of wifi network)
+const char* password = "securetest"; // your network password
+#endif
+
+//const char*  server = "server.local";  // Server hostname
+const IPAddress server = IPAddress(192, 168, 0, 14);  // Server IP address
+const int    port = 8443; // server's port (8883 for MQTT)
+
+const char*  pskIdent = "Client_identity"; // PSK identity (sometimes called key hint)
+const char*  psKey = "1a2b3c4d"; // PSK Key (must be hex string without 0x)
+
+WiFiClientSecure client;
+
+void setup() {
+  //Initialize serial and wait for port to open:
+  Serial.begin(115200);
+  delay(100);
+
+  Serial.print("Attempting to connect to SSID: ");
+  Serial.println(ssid);
+  WiFi.begin(ssid, password);
+
+  // attempt to connect to Wifi network:
+  while (WiFi.status() != WL_CONNECTED) {
+    Serial.print(".");
+    // wait 1 second for re-trying
+    delay(1000);
+  }
+
+  Serial.print("Connected to ");
+  Serial.println(ssid);
+
+  client.setPreSharedKey(pskIdent, psKey);
+
+  Serial.println("\nStarting connection to server...");
+  if (!client.connect(server, port))
+    Serial.println("Connection failed!");
+  else {
+    Serial.println("Connected to server!");
+    // Make a HTTP request:
+    client.println("GET /a/check HTTP/1.0");
+    client.print("Host: ");
+    client.println(server);
+    client.println("Connection: close");
+    client.println();
+
+    while (client.connected()) {
+      String line = client.readStringUntil('\n');
+      if (line == "\r") {
+        Serial.println("headers received");
+        break;
+      }
+    }
+    // if there are incoming bytes available
+    // from the server, read them and print them:
+    while (client.available()) {
+      char c = client.read();
+      Serial.write(c);
+    }
+
+    client.stop();
+  }
+}
+
+void loop() {
+  // do nothing
+}