Generate device name

esp32_device/.vscode/settings.json

@@ -6,5 +6,12 @@
   "idf.openOcdConfigs": [
     "interface/ftdi/esp32_devkitj_v1.cfg",
     "target/esp32.cfg"
-  ]
+  ],
+  "files.associations": {
+    "dev_name.h": "c",
+    "stdio.h": "c",
+    "storage.h": "c",
+    "cstdlib": "c",
+    "cstring": "c"
+  }
 }

esp32_device/main/CMakeLists.txt

@@ -1,2 +1,3 @@
-idf_component_register(SRCS "main.c"
+idf_component_register(SRCS "random.c" "storage.c" "main.c"
+                        "dev_name.c"
                     INCLUDE_DIRS ".")

esp32_device/main/constants.h

@@ -0,0 +1,6 @@
+#pragma once
+
+/**
+ * Device name len
+ */
+#define DEV_NAME_LEN 10

esp32_device/main/dev_name.c

@@ -0,0 +1,40 @@
+#include "stddef.h"
+#include "dev_name.h"
+#include "storage.h"
+#include "stdio.h"
+#include "random.h"
+#include "constants.h"
+#include "string.h"
+
+#define DEV_PREFIX "ESP32 "
+
+bool dev_generate_name_if_required()
+{
+    // Check if a device name has already been defined
+    if (storage_get_dev_name(NULL) > 0)
+        return false;
+
+    // Generate random device name
+    char name[DEV_NAME_LEN];
+    rand_str(DEV_NAME_LEN - 1, name);
+    storage_set_dev_name(name);
+
+    return true;
+}
+
+char *dev_name()
+{
+    size_t len = storage_get_dev_name(NULL);
+
+    char *dev = malloc(len + strlen(DEV_PREFIX) + 1);
+    if (dev == NULL)
+    {
+        printf("Failed to allocate memory to store dev name!\n");
+        return NULL;
+    }
+
+    strcpy(dev, DEV_PREFIX);
+    storage_get_dev_name(dev + strlen(DEV_PREFIX));
+
+    return dev;
+}

esp32_device/main/dev_name.h

@@ -0,0 +1,33 @@
+/**
+ * Device name management
+ */
+
+#pragma once
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /**
+     * Generate random device name, if not existent
+     */
+    bool dev_generate_name_if_required();
+
+    /**
+     * Clear device name
+     */
+    void dev_remove_name();
+
+    /**
+     * Get current device name. This value MUST be freed after usage
+     *
+     * @return NULL if no name was already defined.
+     */
+    char *dev_name();
+
+#ifdef __cplusplus
+}
+#endif

esp32_device/main/main.c

@@ -1,9 +1,29 @@
 #include <stdio.h>
 #include "esp_system.h"
 
+#include "dev_name.h"
+#include "storage.h"
+
 void app_main(void)
 {
-    printf("\n\n\nhello world and bye\n\n\n");
+    printf("\n");
+
+    if (storage_init() == false)
+    {
+        printf("Failed to init storage!\n");
+        fflush(stdout);
+        esp_restart();
+    }
+
+    if (dev_generate_name_if_required())
+    {
+        printf("Generated a new device name\n");
+    }
+
+    char *name = dev_name();
+    printf("Dev name: %s\n", name);
+    free(name);
+
     fflush(stdout);
     esp_restart();
 }

esp32_device/main/random.c

@@ -0,0 +1,31 @@
+#include "random.h"
+#include "esp_random.h"
+
+void rand_str(size_t len, char *dest)
+{
+    for (size_t i = 0; i < len; i++)
+    {
+        uint32_t v = esp_random() % (26 * 2 + 10);
+
+        // Upper case letter
+        if (v < 26)
+        {
+            dest[i] = 65 + v;
+            continue;
+        }
+        v -= 26;
+
+        // Lower case letter
+        if (v < 26)
+        {
+            dest[i] = 97 + v;
+            continue;
+        }
+        v -= 26;
+
+        // Digit
+        dest[i] = 48 + (v % 10);
+    }
+
+    dest[len] = '\0';
+}

esp32_device/main/random.h

@@ -0,0 +1,21 @@
+/**
+ * Random utilities
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /**
+     * Generate random string of given size
+     */
+    void rand_str(size_t len, char *dest);
+
+#ifdef __cplusplus
+}
+#endif

esp32_device/main/storage.c

@@ -0,0 +1,55 @@
+#include "constants.h"
+#include "storage.h"
+#include "nvs_flash.h"
+#include "nvs.h"
+#include <string.h>
+
+#define STORAGE_NAMESPACE "storage"
+
+#define DEV_NAME_KEY "dev_name"
+
+bool storage_init()
+{
+    esp_err_t err = nvs_flash_init();
+    if (err == ESP_ERR_NVS_NO_FREE_PAGES || err == ESP_ERR_NVS_NEW_VERSION_FOUND)
+    {
+        printf("Need to reset storage\n");
+
+        // NVS partition was truncated and needs to be erased
+        // Retry nvs_flash_init
+        ESP_ERROR_CHECK(nvs_flash_erase());
+        err = nvs_flash_init();
+    }
+
+    return err == ESP_OK;
+}
+
+void storage_set_dev_name(const char *name)
+{
+    nvs_handle_t my_handle;
+
+    ESP_ERROR_CHECK(nvs_open(STORAGE_NAMESPACE, NVS_READWRITE, &my_handle));
+
+    ESP_ERROR_CHECK(nvs_set_blob(my_handle, DEV_NAME_KEY, name, strlen(name)));
+
+    nvs_close(my_handle);
+}
+
+size_t storage_get_dev_name(char *dest)
+{
+    nvs_handle_t my_handle;
+
+    ESP_ERROR_CHECK(nvs_open(STORAGE_NAMESPACE, NVS_READWRITE, &my_handle));
+
+    size_t len = (dest == NULL ? 0 : DEV_NAME_LEN);
+    esp_err_t res = nvs_get_blob(my_handle, DEV_NAME_KEY, dest, &len);
+
+    nvs_close(my_handle);
+
+    if (res == ESP_ERR_NVS_NOT_FOUND || len == 0)
+        return 0;
+
+    ESP_ERROR_CHECK(res);
+
+    return len;
+}

esp32_device/main/storage.h

@@ -0,0 +1,32 @@
+/**
+ * Storage management
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /**
+     * Initialize storage
+     */
+    bool storage_init();
+
+    /**
+     * Write device name
+     */
+    void storage_set_dev_name(const char *name);
+
+    /**
+     * Get current device name
+     */
+    size_t storage_get_dev_name(char *dest);
+
+#ifdef __cplusplus
+}
+#endif