Generate device EUI from MAC

.vscode/settings.json

@@ -4,6 +4,8 @@
         "config.h": "c",
         "sdkconfig.h": "c",
         "oslmic.h": "c",
-        "hal_esp32.h": "c"
+        "hal_esp32.h": "c",
+        "esp_log.h": "c",
+        "nvs_flash.h": "c"
     }
 }

examples/mac_address/Makefile

@@ -0,0 +1,3 @@
+PROJECT_NAME := mac_address
+
+include $(IDF_PATH)/make/project.mk

examples/mac_address/main/main.cpp

@@ -0,0 +1,96 @@
+/*******************************************************************************
+ * 
+ * ttn-esp32 - The Things Network device library for ESP-IDF / SX127x
+ * 
+ * Copyright (c) 2018 Manuel Bleichenbacher
+ * 
+ * Licensed under MIT License
+ * https://opensource.org/licenses/MIT
+ *
+ * Sample program showing how to provision the keys from the built-in MAC.
+ *******************************************************************************/
+
+#include "freertos/FreeRTOS.h"
+#include "esp_event.h"
+#include "nvs_flash.h"
+
+#include "TheThingsNetwork.h"
+
+// NOTE:
+// The LoRaWAN frequency and the radio chip must be configured by running 'make menuconfig'.
+// Go to Components / The Things Network, select the appropriate values and save.
+
+// Copy the below two lines from the bottom
+// of your device's overview page in the TTN console.
+const char *appEui = "????????????????";
+const char *appKey = "????????????????????????????????";
+
+// Pins and other resources
+#define TTN_SPI_HOST      HSPI_HOST
+#define TTN_SPI_DMA_CHAN  1
+#define TTN_PIN_SPI_SCLK  5
+#define TTN_PIN_SPI_MOSI  27
+#define TTN_PIN_SPI_MISO  19
+#define TTN_PIN_NSS       18
+#define TTN_PIN_RXTX      TTN_NOT_CONNECTED
+#define TTN_PIN_RST       TTN_NOT_CONNECTED
+#define TTN_PIN_DIO0      26
+#define TTN_PIN_DIO1      33
+
+static TheThingsNetwork ttn;
+
+const unsigned TX_INTERVAL = 30;
+static uint8_t msgData[] = "Hello, world";
+
+
+void sendMessages(void* pvParameter)
+{
+    while (1) {
+        printf("Sending message...\n");
+        TTNResponseCode res = ttn.transmitMessage(msgData, sizeof(msgData) - 1);
+        printf(res == kTTNSuccessfulTransmission ? "Message sent.\n" : "Transmission failed.\n");
+
+        vTaskDelay(TX_INTERVAL * 1000 / portTICK_PERIOD_MS);
+    }
+}
+
+extern "C" void app_main(void)
+{
+    esp_err_t err;
+    // Initialize the GPIO ISR handler service
+    err = gpio_install_isr_service(ESP_INTR_FLAG_IRAM);
+    ESP_ERROR_CHECK(err);
+
+    // Initialize the NVS (non-volatile storage) for saving and restoring the keys
+    err = nvs_flash_init();
+    ESP_ERROR_CHECK(err);
+
+    // Initialize SPI bus
+    spi_bus_config_t spi_bus_config;
+    spi_bus_config.miso_io_num = TTN_PIN_SPI_MISO;
+    spi_bus_config.mosi_io_num = TTN_PIN_SPI_MOSI;
+    spi_bus_config.sclk_io_num = TTN_PIN_SPI_SCLK;
+    spi_bus_config.quadwp_io_num = -1;
+    spi_bus_config.quadhd_io_num = -1;
+    spi_bus_config.max_transfer_sz = 0;
+    err = spi_bus_initialize(TTN_SPI_HOST, &spi_bus_config, TTN_SPI_DMA_CHAN);
+    ESP_ERROR_CHECK(err);
+
+    // Configure the SX127x pins
+    ttn.configurePins(TTN_SPI_HOST, TTN_PIN_NSS, TTN_PIN_RXTX, TTN_PIN_RST, TTN_PIN_DIO0, TTN_PIN_DIO1);
+
+    ttn.provisionWithMAC(appEui, appKey);
+
+    ttn.startProvisioningTask();
+
+    printf("Joining...\n");
+    if (ttn.join())
+    {
+        printf("Joined.\n");
+        xTaskCreate(sendMessages, "send_messages", 1024 * 4, (void* )0, 3, NULL);
+    }
+    else
+    {
+        printf("Join failed. Goodbye\n");
+    }
+}

include/TheThingsNetwork.h

@@ -104,6 +104,32 @@ public:
      */
     bool provision(const char *devEui, const char *appEui, const char *appKey);
 
+    /**
+     * @brief Sets the information needed to activate the device via OTAA, using the MAC to generate the device EUI
+     * and without actually activating.
+     * 
+     * The generated device EUI and the provided app EUI and app key are saved in non-volatile memory. Before
+     * this function is called, 'nvs_flash_init' must have been called once.
+     * 
+     * The device EUI is generated by retrieving the ESP32's WiFi MAC address and expanding it into a device EUI
+     * by adding FFFE in the middle. So the MAC address A0:B1:C2:01:02:03 becomes the EUI A0:B1:C2:FF:FE:01:02:03.
+     * The TTN console requires the device EUI in MSB format, so it has to be reversed and entered as
+     * "03 02 01 FE FF C2 B1 A0".
+     * 
+     * Generating the device EUI from the MAC address allows to flash the same app EUI and app key to a batch of
+     * devices. However, using the same app key for multiple devices is insecure. Only use this approach if
+     * it is okay for that the LoRa communication of your application can easily be intercepted and that
+     * forged data can be injected.
+     * 
+     * Call join() without arguments to activate.
+     * 
+     * @param appEui  Application EUI of the device (16 character string with hexadecimal data)
+     * @param appKey  App Key of the device (32 character string with hexadecimal data)
+     * @return true   if the provisioning was successful
+     * @return false  if the provisioning failed
+     */
+    bool provisionWithMAC(const char *appEui, const char *appKey);
+
     /**
      * @brief Start task that listens on configured UART for provisioning commands.
      * 

src/TheThingsNetwork.cpp

@@ -86,6 +86,14 @@ bool TheThingsNetwork::provision(const char *devEui, const char *appEui, const c
     return provisioning_save_keys();
 }
 
+bool TheThingsNetwork::provisionWithMAC(const char *appEui, const char *appKey)
+{
+    if (!provisioning_from_mac(appEui, appKey))
+        return false;
+    
+    return provisioning_save_keys();
+}
+
 void TheThingsNetwork::startProvisioningTask()
 {
 #if !defined(CONFIG_TTN_PROVISION_UART_NONE)

src/provisioning.c

@@ -14,6 +14,7 @@
 #include "driver/uart.h"
 #include "esp_event.h"
 #include "esp_log.h"
+#include "esp_system.h"
 #include "nvs_flash.h"
 #include "provisioning.h"
 #include "lmic.h"
@@ -28,6 +29,7 @@ static const char *NVS_FLASH_KEY_DEV_EUI = "devEui";
 static const char *NVS_FLASH_KEY_APP_EUI = "appEui";
 static const char *NVS_FLASH_KEY_APP_KEY = "appKey";
 
+static bool provisioning_decode(bool incl_dev_eui, const char *dev_eui, const char *app_eui, const char *app_key);
 static void provisioning_task(void* pvParameter);
 static void provisioning_add_line_data(int numBytes);
 static void provisioning_detect_line_end(int start_at);
@@ -195,6 +197,7 @@ void provisioning_process_line()
     // Expected format:
     // AT+PROV?
     // AT+PROV=hex16-hex16-hex32
+    // AT+MAC?
     if (strcmp(line_buf, "AT+PROV?") == 0)
     {
         uint8_t binbuf[8];
@@ -233,6 +236,22 @@ void provisioning_process_line()
             is_ok = false;
         }
     }
+    else if (strcmp(line_buf, "AT+MAC?") == 0)
+    {
+        uint8_t mac[6];
+        char hexbuf[12];
+
+        esp_err_t err = esp_efuse_mac_get_default(mac);
+        ESP_ERROR_CHECK(err);
+
+        bin_to_hex_str(mac, 6, hexbuf);
+        for (int i = 0; i < 12; i += 2) {
+            if (i > 0)
+                uart_write_bytes(UART_NUM, ":", 1);
+            uart_write_bytes(UART_NUM, hexbuf + i, 2);
+        }
+        uart_write_bytes(UART_NUM, "\r\n", 2);
+    }
     else if (strcmp(line_buf, "AT+PROVQ") == 0)
     {
         quit_task = true;
@@ -276,17 +295,41 @@ bool provisioning_have_keys()
 }
 
 bool provisioning_decode_keys(const char *dev_eui, const char *app_eui, const char *app_key)
+{
+    return provisioning_decode(true, dev_eui, app_eui, app_key);
+}
+
+bool provisioning_from_mac(const char *app_eui, const char *app_key)
+{
+    uint8_t mac[6];
+    esp_err_t err = esp_efuse_mac_get_default(mac);
+    ESP_ERROR_CHECK(err);
+    
+    global_dev_eui[0] = mac[0];
+    global_dev_eui[1] = mac[1];
+    global_dev_eui[2] = mac[2];
+    global_dev_eui[3] = 0xff;
+    global_dev_eui[4] = 0xfe;
+    global_dev_eui[5] = mac[3];
+    global_dev_eui[6] = mac[4];
+    global_dev_eui[7] = mac[5];
+
+    return provisioning_decode(false, NULL, app_eui, app_key);
+}
+
+bool provisioning_decode(bool incl_dev_eui, const char *dev_eui, const char *app_eui, const char *app_key)
 {
     uint8_t buf_dev_eui[8];
     uint8_t buf_app_eui[8];
     uint8_t buf_app_key[16];
 
-    if (strlen(dev_eui) != 16 || !hex_str_to_bin(dev_eui, buf_dev_eui, 8))
+    if (incl_dev_eui && (strlen(dev_eui) != 16 || !hex_str_to_bin(dev_eui, buf_dev_eui, 8)))
     {
         ESP_LOGW(TAG, "Invalid device EUI: %s", dev_eui);
         return false;
     }
 
+    if (incl_dev_eui)
         swap_bytes(buf_dev_eui, 8);
 
     if (strlen(app_eui) != 16 || !hex_str_to_bin(app_eui, buf_app_eui, 8))
@@ -303,6 +346,7 @@ bool provisioning_decode_keys(const char *dev_eui, const char *app_eui, const ch
         return false;
     }
 
+    if (incl_dev_eui)
         memcpy(global_dev_eui, buf_dev_eui, sizeof(global_dev_eui));
     memcpy(global_app_eui, buf_app_eui, sizeof(global_app_eui));
     memcpy(global_app_key, buf_app_key, sizeof(global_app_key));

src/provisioning.h

@@ -24,6 +24,7 @@ extern "C" {
 void provisioning_start_task();
 bool provisioning_have_keys();
 bool provisioning_decode_keys(const char *dev_eui, const char *app_eui, const char *app_key);
+bool provisioning_from_mac(const char *app_eui, const char *app_key);
 bool provisioning_save_keys();
 bool provisioning_restore_keys(bool silent);