esp8266: add connected function

lib/radio_esp8266.c

@@ -141,10 +141,32 @@ void radio_esp8266_reset(void)
 	while(rx_used < 13 || memcmp((char*)&rx_buffer[rx_used - 13], "WIFI GOT IP\r\n", 13) != 0) { // wait to have IP
 		 __WFI(); // sleep until something happened
 	}
-	radio_esp8266_transmit((uint8_t*)"ATE0\r\n", 6); // disable echoing
+}
+
+bool radio_esp8266_connected(void)
+{
+	// verify if we ware connect to access point
+	radio_esp8266_transmit_at("+CWJAP_CUR?");
 	while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
 		__WFI(); // sleep until something happened
 	}
+	if (rx_used < 5 || 0 == memcmp((char*)&rx_buffer[rx_used - 5], "No AP", 5)) {
+		rx_used = 0; // finished using the buffer
+		return false;
+	}
+
+	// check if we have an IP
+	radio_esp8266_transmit_at("+CIPSTA_CUR?"); // verify if module is present
+	while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
+		__WFI(); // sleep until something happened
+	}
+	if (rx_used < 17 || '0' == rx_buffer[16]) { // check for +CIPSTA_CUR:ip:"0.0.0.0"
+		rx_used = 0;
+		return false;
+	}
+
+	rx_used = 0; // clear buffer
+	return true;
 }
 
 void radio_esp8266_tcp_open(char* host, uint16_t port)

lib/radio_esp8266.h

@@ -22,6 +22,10 @@ extern uint16_t radio_esp8266_received_len;
 void radio_esp8266_setup(void);
 /** reset ESP */
 void radio_esp8266_reset(void);
+/** check if connect to the network
+ *  @return if connected to network
+ */
+bool radio_esp8266_connected(void);
 /** establish TCP connection
  *  @param[in] host host to connect to
  *  @param[in] port TCP port to connect to