Add native Wi-Fi management and persistence

src/wifi_config.h

@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-3.0-only */
+/*
+ * Native ESP-IDF Wi-Fi configuration and persistence.
+ *
+ * The public structures below are also the version-1 NVS wire format. Keep
+ * every field fixed-width and introduce a new schema version for layout
+ * changes; do not silently reinterpret an existing blob.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "esp_err.h"
+
+#define WIFI_CONFIG_SCHEMA_VERSION 1U
+#define WIFI_CONFIG_BLOB_SIZE 528U
+#define WIFI_CONFIG_STA_PROFILE_BLOB_SIZE 104U
+
+#define WIFI_CONFIG_NVS_NAMESPACE "wifi_app"
+#define WIFI_CONFIG_NVS_BLOB_KEY "config"
+
+#define WIFI_CONFIG_STA_PROFILE_COUNT 4U
+#define WIFI_CONFIG_SSID_MAX_LEN 32U
+#define WIFI_CONFIG_PSK_MIN_LEN 8U
+#define WIFI_CONFIG_PSK_MAX_LEN 63U
+#define WIFI_CONFIG_DEFAULT_AP_PSK_LEN 16U
+#define WIFI_CONFIG_AP_CHANNEL_MIN 1U
+#define WIFI_CONFIG_AP_CHANNEL_MAX 11U
+
+/* uint8_t aliases keep the persisted representation independent of enum size. */
+typedef uint8_t wifi_config_ap_policy_t;
+enum {
+    WIFI_CONFIG_AP_POLICY_OFF = 0U,
+    WIFI_CONFIG_AP_POLICY_FALLBACK = 1U,
+    WIFI_CONFIG_AP_POLICY_ALWAYS = 2U,
+};
+
+typedef uint8_t wifi_config_security_t;
+enum {
+    /* ESP-IDF thresholds can express WPA2-or-stronger, not WPA2-only. */
+    WIFI_CONFIG_SECURITY_MIXED = 0U,
+    WIFI_CONFIG_SECURITY_WPA3 = 1U,
+};
+
+typedef uint8_t wifi_config_load_source_t;
+enum {
+    WIFI_CONFIG_LOAD_GENERATED_MISSING = 0U,
+    WIFI_CONFIG_LOAD_STORED = 1U,
+    WIFI_CONFIG_LOAD_GENERATED_INVALID = 2U,
+};
+
+typedef struct {
+    /* Persisted booleans use 0/1 bytes so the blob layout remains fixed. */
+    uint8_t enabled;
+    uint8_t priority;
+    wifi_config_security_t security;
+    uint8_t ssid_len;
+    uint8_t psk_len;
+    uint8_t reserved[3];
+
+    /* Lengths are authoritative; these fixed-width byte arrays need no NUL. */
+    uint8_t ssid[WIFI_CONFIG_SSID_MAX_LEN];
+    uint8_t psk[WIFI_CONFIG_PSK_MAX_LEN];
+    uint8_t reserved_tail[1];
+} wifi_config_sta_profile_t;
+
+typedef struct {
+    uint32_t schema_version;
+    uint16_t blob_size;
+    uint8_t enabled_at_boot;
+    wifi_config_ap_policy_t ap_policy;
+    uint8_t ap_ssid_len;
+    uint8_t ap_psk_len;
+    uint8_t ap_channel;
+    uint8_t reserved[5];
+
+    uint8_t ap_ssid[WIFI_CONFIG_SSID_MAX_LEN];
+    uint8_t ap_psk[WIFI_CONFIG_PSK_MAX_LEN];
+    uint8_t reserved_tail[1];
+
+    wifi_config_sta_profile_t profiles[WIFI_CONFIG_STA_PROFILE_COUNT];
+} wifi_app_config_t;
+
+/* Seed the credential DRBG before Wi-Fi, Bluetooth, or ADC use. */
+esp_err_t wifi_config_entropy_init(void);
+
+/* Generates a unique AP SSID and a fresh random AP password. */
+esp_err_t wifi_config_defaults(wifi_app_config_t *config);
+esp_err_t wifi_config_validate(const wifi_app_config_t *config);
+
+bool wifi_config_parse_ap_policy(const char *text, wifi_config_ap_policy_t *value);
+const char *wifi_config_ap_policy_to_string(wifi_config_ap_policy_t value);
+bool wifi_config_parse_security(const char *text, wifi_config_security_t *value);
+const char *wifi_config_security_to_string(wifi_config_security_t value);
+
+/*
+ * Storage uses only wifi_app/config. Invalid, stale, or absent blobs are left
+ * untouched. source distinguishes first boot from incompatible stored data so
+ * callers never overwrite a potentially migratable schema automatically.
+ */
+esp_err_t wifi_config_storage_init(void);
+esp_err_t wifi_config_load(wifi_app_config_t *config,
+                           wifi_config_load_source_t *source);
+esp_err_t wifi_config_save(const wifi_app_config_t *config);
+
+/* Pass NULL to generate fresh defaults, or supply validated defaults to save. */
+esp_err_t wifi_config_reset_storage(const wifi_app_config_t *defaults);
+
+/* Volatile writes prevent ordinary optimization from eliding secret cleanup. */
+void wifi_config_secure_wipe(void *data, size_t size);