Momentum-Apps/esubghz_chat.c

#include <furi.h>
#include <furi_hal.h>
#include <gui/elements.h>
#include <gui/gui.h>
#include <gui/modules/text_box.h>
#include <gui/modules/text_input.h>
#include <gui/view_dispatcher_i.h>
#include <gui/view_port_i.h>
#include <gui/scene_manager.h>
#include <toolbox/sha256.h>
#include <notification/notification_messages.h>
#include <lib/subghz/devices/cc1101_int/cc1101_int_interconnect.h>
#include <lib/subghz/subghz_tx_rx_worker.h>

#include "esubghz_chat_icons.h"

#include "crypto/gcm.h"

#define APPLICATION_NAME "ESubGhzChat"

#define DEFAULT_FREQ 433920000

#define KEY_BITS 256
#define IV_BYTES 12
#define TAG_BYTES 16

#define RX_TX_BUFFER_SIZE 1024

#define CHAT_BOX_STORE_SIZE 4096
#define TEXT_INPUT_STORE_SIZE 256

#define TICK_INTERVAL 50
#define MESSAGE_COMPLETION_TIMEOUT 500
#define TIMEOUT_BETWEEN_MESSAGES 500

#define KBD_UNLOCK_CNT 3
#define KBD_UNLOCK_TIMEOUT 1000

typedef struct {
	SceneManager *scene_manager;
	ViewDispatcher *view_dispatcher;
	NotificationApp *notification;

	// UI elements
	TextBox *chat_box;
	FuriString *chat_box_store;
	TextInput *text_input;
	char text_input_store[TEXT_INPUT_STORE_SIZE + 1];

	// for Sub-GHz
	uint32_t frequency;
	SubGhzTxRxWorker *subghz_worker;
	const SubGhzDevice *subghz_device;

	// message assembly before TX
	FuriString *name_prefix;
	FuriString *msg_input;

	// encryption
	bool encrypted;
	gcm_context gcm_ctx;

	// RX and TX buffers
	uint8_t rx_buffer[RX_TX_BUFFER_SIZE];
	uint8_t tx_buffer[RX_TX_BUFFER_SIZE];
	char rx_str_buffer[RX_TX_BUFFER_SIZE + 1];
	volatile uint32_t last_time_rx_data;

	// for locking
	ViewPortDrawCallback orig_draw_cb;
	ViewPortInputCallback orig_input_cb;
	bool kbd_locked;
	uint32_t kbd_lock_msg_ticks;
	uint8_t kbd_lock_count;
	bool kbd_ok_input_ongoing;
} ESubGhzChatState;

typedef enum {
	ESubGhzChatScene_FreqInput,
	ESubGhzChatScene_PassInput,
	ESubGhzChatScene_ChatInput,
	ESubGhzChatScene_ChatBox,
	ESubGhzChatScene_MAX
} ESubGhzChatScene;

typedef enum {
	ESubGhzChatView_Input,
	ESubGhzChatView_ChatBox,
} ESubGhzChatView;

typedef enum {
	ESubGhzChatEvent_FreqEntered,
	ESubGhzChatEvent_PassEntered,
	ESubGhzChatEvent_MsgEntered
} ESubGhzChatEvent;

/* Function to clear sensitive memory. */
static void esubghz_chat_explicit_bzero(void *s, size_t len)
{
	memset(s, 0, len);
	asm volatile("" ::: "memory");
}

/* Callback for RX events from the Sub-GHz worker. Records the current ticks as
 * the time of the last reception. */
static void have_read_cb(void* context)
{
	furi_assert(context);
	ESubGhzChatState* state = context;

	state->last_time_rx_data = furi_get_tick();
}

/* Decrypts a message for post_rx(). */
static bool post_rx_decrypt(ESubGhzChatState *state, size_t rx_size)
{
	if (rx_size < IV_BYTES + TAG_BYTES + 1) {
		return false;
	}

	int ret = gcm_auth_decrypt(&(state->gcm_ctx),
			state->rx_buffer, IV_BYTES,
			NULL, 0,
			state->rx_buffer + IV_BYTES,
			(uint8_t *) state->rx_str_buffer,
			rx_size - (IV_BYTES + TAG_BYTES),
			state->rx_buffer + rx_size - TAG_BYTES,
			TAG_BYTES);
	state->rx_str_buffer[rx_size - (IV_BYTES + TAG_BYTES)] = 0;

	return (ret == 0);
}

/* Post RX handler, decrypts received messages, displays them in the text box
 * and sends a notification. */
static void post_rx(ESubGhzChatState *state, size_t rx_size)
{
	furi_assert(state);

	if (rx_size == 0) {
		return;
	}

	furi_check(rx_size <= RX_TX_BUFFER_SIZE);

	/* decrypt if necessary */
	if (!state->encrypted) {
		memcpy(state->rx_str_buffer, state->rx_buffer, rx_size);
		state->rx_str_buffer[rx_size] = 0;

		/* remove trailing newline if it is there, for compat with CLI
		 * Sub-GHz chat */
		if (state->rx_str_buffer[rx_size - 1] == '\n') {
			state->rx_str_buffer[rx_size - 1] = 0;
		}
	} else {
		/* if decryption fails output an error message */
		if (!post_rx_decrypt(state, rx_size)) {
			strcpy(state->rx_str_buffer, "ERR: Decryption failed!");
		}
	}

	/* append message to text box */
	furi_string_cat_printf(state->chat_box_store, "\n%s",
			state->rx_str_buffer);

	/* send notification (make the flipper vibrate) */
	notification_message(state->notification, &sequence_single_vibro);

	/* reset text box contents and focus */
	text_box_set_text(state->chat_box,
			furi_string_get_cstr(state->chat_box_store));
	text_box_set_focus(state->chat_box, TextBoxFocusEnd);
}

/* Sends FreqEntered event to scene manager and displays the frequency in the
 * text box. */
static void freq_input_cb(void *context)
{
	furi_assert(context);
	ESubGhzChatState* state = context;

	furi_string_cat_printf(state->chat_box_store, "Frequency: %lu",
			state->frequency);

	scene_manager_handle_custom_event(state->scene_manager,
			ESubGhzChatEvent_FreqEntered);
}

/* Validates the entered frequency. */
static bool freq_input_validator(const char *text, FuriString *error,
		void *context)
{
	furi_assert(text);
	furi_assert(error);

	furi_assert(context);
	ESubGhzChatState* state = context;

        int ret = sscanf(text, "%lu", &(state->frequency));
	if (ret != 1) {
		furi_string_printf(error, "Please enter\nfrequency\nin Hz!");
		return false;
	}

	if (!subghz_devices_is_frequency_valid(state->subghz_device,
				state->frequency)) {
		furi_string_printf(error, "Frequency\n%lu\n is invalid!",
				state->frequency);
		return false;
	}

#ifdef FW_ORIGIN_Official
	if (!furi_hal_region_is_frequency_allowed(state->frequency)) {
#else /* FW_ORIGIN_Official */
	if (!furi_hal_subghz_is_tx_allowed(state->frequency)) {
#endif /* FW_ORIGIN_Official */
		furi_string_printf(error, "TX forbidden\non frequency\n%lu!",
				state->frequency);
		return false;
	}

	return true;
}

/* Sends PassEntered event to scene manager and displays whether or not
 * encryption has been enabled in the text box. Also clears the text input
 * buffer to remove the password and starts the Sub-GHz worker. */
static void pass_input_cb(void *context)
{
	furi_assert(context);
	ESubGhzChatState* state = context;

	furi_string_cat_printf(state->chat_box_store, "\nEncrypted: %s",
			(state->encrypted ? "yes" : "no"));

	/* clear the text input buffer to remove the password */
	esubghz_chat_explicit_bzero(state->text_input_store,
			sizeof(state->text_input_store));

	subghz_tx_rx_worker_start(state->subghz_worker, state->subghz_device,
			state->frequency);

	scene_manager_handle_custom_event(state->scene_manager,
			ESubGhzChatEvent_PassEntered);
}

/* If a password was entered this derives a key from the password using a
 * single pass of SHA256 and initiates the AES-GCM context for encryption. If
 * the initiation fails, the password is rejected. */
static bool pass_input_validator(const char *text, FuriString *error,
		void *context)
{
	furi_assert(text);
	furi_assert(error);

	furi_assert(context);
	ESubGhzChatState* state = context;

#ifdef FW_ORIGIN_Official
	if (strlen(text) == 0) {
		furi_string_printf(error, "Enter a\npassword!");
		return false;
	}

	if (strcmp(text, " ") == 0) {
#else /* FW_ORIGIN_Official */
	if (strlen(text) == 0) {
#endif /* FW_ORIGIN_Official */
		state->encrypted = false;
		return true;
	}

	unsigned char key[KEY_BITS / 8];

	/* derive a key from the password */
	sha256((unsigned char *) text, strlen(text), key);

	// TODO: remove this
	furi_string_cat_printf(state->chat_box_store, "\nKey:");
	int i;
	for (i = 0; i < KEY_BITS / 8; i++) {
		furi_string_cat_printf(state->chat_box_store, " %02x", key[i]);
	}

	/* initiate the AES-GCM context */
	int ret = gcm_setkey(&(state->gcm_ctx), key, KEY_BITS / 8);

	/* cleanup */
	esubghz_chat_explicit_bzero(key, sizeof(key));

	if (ret != 0) {
		esubghz_chat_explicit_bzero(&(state->gcm_ctx),
				sizeof(state->gcm_ctx));
		furi_string_printf(error, "Failed to\nset key!");
		return false;
	}

	state->encrypted = true;

	return true;
}

/* If no message was entred this simply emits a MsgEntered event to the scene
 * manager to switch to the text box. If a message was entered it is appended
 * to the name string. The result is encrypted, if encryption is enabled, and
 * then copied into the TX buffer. The contents of the TX buffer are then
 * transmitted. The sent message is appended to the text box and a MsgEntered
 * event is sent to the scene manager to switch to the text box view. */
static void chat_input_cb(void *context)
{
	furi_assert(context);
	ESubGhzChatState* state = context;

	/* no message, just switch to the text box view */
#ifdef FW_ORIGIN_Official
	if (strcmp(state->text_input_store, " ") == 0) {
#else /* FW_ORIGIN_Official */
	if (strlen(state->text_input_store) == 0) {
#endif /* FW_ORIGIN_Official */
		scene_manager_handle_custom_event(state->scene_manager,
				ESubGhzChatEvent_MsgEntered);
		return;
	}

	/* concatenate the name prefix and the actual message */
	furi_string_set(state->msg_input, state->name_prefix);
	furi_string_cat_str(state->msg_input, state->text_input_store);

	/* append the message to the chat box */
	furi_string_cat_printf(state->chat_box_store, "\n%s",
		furi_string_get_cstr(state->msg_input));

	/* encrypt message if necessary */
	size_t msg_len = strlen(furi_string_get_cstr(state->msg_input));
	size_t tx_size = msg_len;
	if (state->encrypted) {
		tx_size += IV_BYTES + TAG_BYTES;
		furi_check(tx_size <= sizeof(state->tx_buffer));

		furi_hal_random_fill_buf(state->tx_buffer, IV_BYTES);
		gcm_crypt_and_tag(&(state->gcm_ctx), ENCRYPT,
				state->tx_buffer, IV_BYTES,
				NULL, 0,
				(unsigned char *)
				furi_string_get_cstr(state->msg_input),
				state->tx_buffer + IV_BYTES,
				msg_len,
				state->tx_buffer + IV_BYTES + msg_len,
				TAG_BYTES);
	} else {
		tx_size += 2;
		furi_check(tx_size <= sizeof(state->tx_buffer));
		memcpy(state->tx_buffer,
				furi_string_get_cstr(state->msg_input),
				msg_len);

		/* append \r\n for compat with Sub-GHz CLI chat */
		state->tx_buffer[msg_len] = '\r';
		state->tx_buffer[msg_len + 1] = '\n';
	}

	/* clear message input buffer */
	furi_string_set_char(state->msg_input, 0, 0);

	// TODO: remove this
	furi_string_cat_printf(state->chat_box_store, "\nTXed (HEX):");
	size_t i;
	for (i = 0; i < tx_size; i++) {
		furi_string_cat_printf(state->chat_box_store, " %02x",
				state->tx_buffer[i]);
	}

	/* transmit */
	subghz_tx_rx_worker_write(state->subghz_worker, state->tx_buffer,
			tx_size);

	/* switch to text box view */
	scene_manager_handle_custom_event(state->scene_manager,
			ESubGhzChatEvent_MsgEntered);
}

/* Prepares the frequency input scene. */
static void scene_on_enter_freq_input(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_enter_freq_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	snprintf(state->text_input_store, TEXT_INPUT_STORE_SIZE, "%lu",
			(uint32_t) DEFAULT_FREQ);
	text_input_reset(state->text_input);
	text_input_set_result_callback(
			state->text_input,
			freq_input_cb,
			state,
			state->text_input_store,
			sizeof(state->text_input_store),
			true);
	text_input_set_validator(
			state->text_input,
			freq_input_validator,
			state);
	text_input_set_header_text(
			state->text_input,
			"Frequency");

	view_dispatcher_switch_to_view(state->view_dispatcher, ESubGhzChatView_Input);
}

/* Handles scene manager events for the frequency input scene. */
static bool scene_on_event_freq_input(void* context, SceneManagerEvent event)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_event_freq_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	bool consumed = false;

	switch(event.type) {
	case SceneManagerEventTypeCustom:
		switch(event.event) {
		/* switch to password input scene */
		case ESubGhzChatEvent_FreqEntered:
			scene_manager_next_scene(state->scene_manager,
					ESubGhzChatScene_PassInput);
			consumed = true;
			break;
		}
		break;

	case SceneManagerEventTypeBack:
		/* stop the application if the user presses back here */
		view_dispatcher_stop(state->view_dispatcher);
		consumed = true;
		break;

	default:
		consumed = false;
		break;
	}

	return consumed;
}

/* Cleans up the frequency input scene. */
static void scene_on_exit_freq_input(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_exit_freq_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	text_input_reset(state->text_input);
}

/* Prepares the password input scene. */
static void scene_on_enter_pass_input(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_enter_pass_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	state->text_input_store[0] = 0;
	text_input_reset(state->text_input);
	text_input_set_result_callback(
			state->text_input,
			pass_input_cb,
			state,
			state->text_input_store,
			sizeof(state->text_input_store),
			true);
	text_input_set_validator(
			state->text_input,
			pass_input_validator,
			state);
	text_input_set_header_text(
			state->text_input,
#ifdef FW_ORIGIN_Official
			"Password (space for no encr.)");
#else /* FW_ORIGIN_Official */
			"Password (empty for no encr.)");
	text_input_set_minimum_length(state->text_input, 0);
#endif /* FW_ORIGIN_Official */

	view_dispatcher_switch_to_view(state->view_dispatcher, ESubGhzChatView_Input);
}

/* Handles scene manager events for the password input scene. */
static bool scene_on_event_pass_input(void* context, SceneManagerEvent event)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_event_pass_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	bool consumed = false;

	switch(event.type) {
	case SceneManagerEventTypeCustom:
		switch(event.event) {
		/* switch to message input scene */
		case ESubGhzChatEvent_PassEntered:
			scene_manager_next_scene(state->scene_manager,
					ESubGhzChatScene_ChatInput);
			consumed = true;
			break;
		}
		break;

	case SceneManagerEventTypeBack:
		/* stop the application if the user presses back here */
		view_dispatcher_stop(state->view_dispatcher);
		consumed = true;
		break;

	default:
		consumed = false;
		break;
	}

	return consumed;
}

/* Cleans up the password input scene. */
static void scene_on_exit_pass_input(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_exit_pass_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	text_input_reset(state->text_input);
}

/* Prepares the message input scene. */
static void scene_on_enter_chat_input(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_enter_chat_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	state->text_input_store[0] = 0;
	text_input_reset(state->text_input);
	text_input_set_result_callback(
			state->text_input,
			chat_input_cb,
			state,
			state->text_input_store,
			sizeof(state->text_input_store),
			true);
	text_input_set_validator(
			state->text_input,
			NULL,
			NULL);
	text_input_set_header_text(
			state->text_input,
#ifdef FW_ORIGIN_Official
			"Message (space for none)");
#else /* FW_ORIGIN_Official */
			"Message");
	text_input_set_minimum_length(state->text_input, 0);
#endif /* FW_ORIGIN_Official */

	view_dispatcher_switch_to_view(state->view_dispatcher, ESubGhzChatView_Input);
}

/* Handles scene manager events for the message input scene. */
static bool scene_on_event_chat_input(void* context, SceneManagerEvent event)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_event_chat_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	bool consumed = false;

	switch(event.type) {
	case SceneManagerEventTypeCustom:
		switch(event.event) {
		/* switch to text box scene */
		case ESubGhzChatEvent_MsgEntered:
			scene_manager_next_scene(state->scene_manager,
					ESubGhzChatScene_ChatBox);
			consumed = true;
			break;
		}
		break;

	case SceneManagerEventTypeBack:
		/* stop the application if the user presses back here */
		view_dispatcher_stop(state->view_dispatcher);
		consumed = true;
		break;

	default:
		consumed = false;
		break;
	}

	return consumed;
}

/* Cleans up the password input scene. */
static void scene_on_exit_chat_input(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_exit_chat_input");

	furi_assert(context);
	ESubGhzChatState* state = context;

	text_input_reset(state->text_input);
}

/* Prepares the text box scene. */
static void scene_on_enter_chat_box(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_enter_chat_box");

	furi_assert(context);
	ESubGhzChatState* state = context;

	text_box_reset(state->chat_box);
	text_box_set_text(state->chat_box,
			furi_string_get_cstr(state->chat_box_store));
	text_box_set_focus(state->chat_box, TextBoxFocusEnd);

	view_dispatcher_switch_to_view(state->view_dispatcher, ESubGhzChatView_ChatBox);
}

/* Handles scene manager events for the text box scene. No events are handled
 * here. */
static bool scene_on_event_chat_box(void* context, SceneManagerEvent event)
{
	UNUSED(event);

	FURI_LOG_T(APPLICATION_NAME, "scene_on_event_chat_box");

	furi_assert(context);

	return false;
}

/* Cleans up the text box scene. */
static void scene_on_exit_chat_box(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "scene_on_exit_chat_box");

	furi_assert(context);
	ESubGhzChatState* state = context;

	text_box_reset(state->chat_box);
}

/* Scene entry handlers. */
static void (*const esubghz_chat_scene_on_enter_handlers[])(void*) = {
	scene_on_enter_freq_input,
	scene_on_enter_pass_input,
	scene_on_enter_chat_input,
	scene_on_enter_chat_box
};

/* Scene event handlers. */
static bool (*const esubghz_chat_scene_on_event_handlers[])(void*, SceneManagerEvent) = {
	scene_on_event_freq_input,
	scene_on_event_pass_input,
	scene_on_event_chat_input,
	scene_on_event_chat_box
};

/* Scene exit handlers. */
static void (*const esubghz_chat_scene_on_exit_handlers[])(void*) = {
	scene_on_exit_freq_input,
	scene_on_exit_pass_input,
	scene_on_exit_chat_input,
	scene_on_exit_chat_box
};

/* Handlers for the scene manager. */
static const SceneManagerHandlers esubghz_chat_scene_event_handlers = {
	.on_enter_handlers = esubghz_chat_scene_on_enter_handlers,
	.on_event_handlers = esubghz_chat_scene_on_event_handlers,
	.on_exit_handlers = esubghz_chat_scene_on_exit_handlers,
	.scene_num = ESubGhzChatScene_MAX};

/* Whether or not to display the locked message. */
static bool kbd_lock_msg_display(ESubGhzChatState *state)
{
	return (state->kbd_lock_msg_ticks != 0);
}

/* Whether or not to hide the locked message again. */
static bool kbd_lock_msg_reset_timeout(ESubGhzChatState *state)
{
	if (state->kbd_lock_msg_ticks == 0) {
		return false;
	}

	if (furi_get_tick() - state->kbd_lock_msg_ticks > KBD_UNLOCK_TIMEOUT) {
		return true;
	}

	return false;
}

/* Resets the timeout for the locked message and turns off the backlight if
 * specified. */
static void kbd_lock_msg_reset(ESubGhzChatState *state, bool backlight_off)
{
	state->kbd_lock_msg_ticks = 0;
	state->kbd_lock_count = 0;

	if (backlight_off) {
		notification_message(state->notification,
				&sequence_display_backlight_off);
	}
}

/* Locks the keyboard. */
static void kbd_lock(ESubGhzChatState *state)
{
	state->kbd_locked = true;
	kbd_lock_msg_reset(state, true);
}

/* Unlocks the keyboard. */
static void kbd_unlock(ESubGhzChatState *state)
{
	state->kbd_locked = false;
	kbd_lock_msg_reset(state, false);
}

/* Custom event callback for view dispatcher. Just calls scene manager. */
static bool esubghz_chat_custom_event_callback(void* context, uint32_t event)
{
	FURI_LOG_T(APPLICATION_NAME, "esubghz_chat_custom_event_callback");
	furi_assert(context);
	ESubGhzChatState* state = context;
	return scene_manager_handle_custom_event(state->scene_manager, event);
}

/* Navigation event callback for view dispatcher. Just calls scene manager. */
static bool esubghz_chat_navigation_event_callback(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "esubghz_chat_navigation_event_callback");
	furi_assert(context);
	ESubGhzChatState* state = context;
	return scene_manager_handle_back_event(state->scene_manager);
}

/* Tick event callback for view dispatcher. Called every TICK_INTERVAL. Resets
 * the locked message if necessary. Retrieves a received message from the
 * Sub-GHz worker and calls post_rx(). Then calls the scene manager. */
static void esubghz_chat_tick_event_callback(void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "esubghz_chat_tick_event_callback");

	furi_assert(context);
	ESubGhzChatState* state = context;

	/* reset locked message if necessary */
	if (kbd_lock_msg_reset_timeout(state)) {
		kbd_lock_msg_reset(state, true);
	}

	/* if the maximum message size was reached or the
	 * MESSAGE_COMPLETION_TIMEOUT has expired, retrieve a message and call
	 * post_rx() */
	size_t avail = 0;
	while ((avail = subghz_tx_rx_worker_available(state->subghz_worker)) >
			0) {
		volatile uint32_t since_last_rx = furi_get_tick() -
			state->last_time_rx_data;
		if (avail < RX_TX_BUFFER_SIZE && since_last_rx <
				MESSAGE_COMPLETION_TIMEOUT) {
			break;
		}

		size_t rx_size = subghz_tx_rx_worker_read(state->subghz_worker,
				state->rx_buffer, RX_TX_BUFFER_SIZE);
		post_rx(state, rx_size);
	}

	/* call scene manager */
	scene_manager_handle_tick_event(state->scene_manager);
}

/* Hooks into the view port's draw callback to overlay the keyboard locked
 * message. */
static void esubghz_hooked_draw_callback(Canvas* canvas, void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "esubghz_hooked_draw_callback");

	furi_assert(canvas);

	furi_assert(context);
	ESubGhzChatState* state = context;

	/* call original callback */
	state->orig_draw_cb(canvas, state->view_dispatcher);

	/* display if the keyboard is locked */
	if (state->kbd_locked) {
		canvas_set_font(canvas, FontPrimary);
		elements_multiline_text_framed(canvas, 42, 30, "Locked");
	}

	/* display the unlock message if necessary */
	if (kbd_lock_msg_display(state)) {
		canvas_set_font(canvas, FontSecondary);
		elements_bold_rounded_frame(canvas, 14, 8, 99, 48);
		elements_multiline_text(canvas, 65, 26, "To unlock\npress:");
		canvas_draw_icon(canvas, 65, 42, &I_Pin_back_arrow_10x8);
		canvas_draw_icon(canvas, 80, 42, &I_Pin_back_arrow_10x8);
		canvas_draw_icon(canvas, 95, 42, &I_Pin_back_arrow_10x8);
		canvas_draw_icon(canvas, 16, 13, &I_WarningDolphin_45x42);
	}
}

/* Hooks into the view port's input callback to handle the user locking the
 * keyboard. */
static void esubghz_hooked_input_callback(InputEvent* event, void* context)
{
	FURI_LOG_T(APPLICATION_NAME, "esubghz_hooked_input_callback");

	furi_assert(event);

	furi_assert(context);
	ESubGhzChatState* state = context;

	/* if the keyboard is locked no key presses are forwarded */
	if (state->kbd_locked) {
		/* key has been pressed, display the unlock message and
		 * initiate the timer */
		if (state->kbd_lock_count == 0) {
			state->kbd_lock_msg_ticks = furi_get_tick();
		}

		/* back button has been pressed, increase the lock counter */
		if (event->key == InputKeyBack && event->type ==
				InputTypeShort) {
			state->kbd_lock_count++;
		}

		/* unlock the keyboard */
		if (state->kbd_lock_count >= KBD_UNLOCK_CNT) {
			kbd_unlock(state);
		}

		/* do not handle the event */
		return;
	}

	if (event->key == InputKeyOk) {
		/* if we are in the chat view and no input is ongoing, allow
		 * locking */
		if (state->view_dispatcher->current_view ==
				text_box_get_view(state->chat_box) &&
				!(state->kbd_ok_input_ongoing)) {
			/* lock keyboard upon long press of Ok button */
			if (event->type == InputTypeLong) {
				kbd_lock(state);
			}

			/* do not handle any Ok key events to prevent blocking
			 * of other keys */
			return;
		}

		/* handle ongoing inputs when chaning to chat view */
		if (event->type == InputTypePress) {
			state->kbd_ok_input_ongoing = true;
		} else if (event->type == InputTypeRelease) {
			state->kbd_ok_input_ongoing = false;
		}
	}

	/* call original callback */
	state->orig_input_cb(event, state->view_dispatcher);
}

static bool helper_strings_alloc(ESubGhzChatState *state)
{
	furi_assert(state);

	state->name_prefix = furi_string_alloc();
	if (state->name_prefix == NULL) {
		return false;
	}

	state->msg_input = furi_string_alloc();
	if (state->msg_input == NULL) {
		furi_string_free(state->name_prefix);
		return false;
	}

	return true;
}

static void helper_strings_free(ESubGhzChatState *state)
{
	furi_assert(state);

	furi_string_free(state->name_prefix);
	furi_string_free(state->msg_input);
}

static bool chat_box_alloc(ESubGhzChatState *state)
{
	furi_assert(state);

	state->chat_box = text_box_alloc();
	if (state->chat_box == NULL) {
		return false;
	}

	state->chat_box_store = furi_string_alloc();
	if (state->chat_box_store == NULL) {
		text_box_free(state->chat_box);
		return false;
	}

	furi_string_reserve(state->chat_box_store, CHAT_BOX_STORE_SIZE);
	furi_string_set_char(state->chat_box_store, 0, 0);
	text_box_set_text(state->chat_box,
			furi_string_get_cstr(state->chat_box_store));
	text_box_set_focus(state->chat_box, TextBoxFocusEnd);

	return true;
}

static void chat_box_free(ESubGhzChatState *state)
{
	furi_assert(state);

	text_box_free(state->chat_box);
	furi_string_free(state->chat_box_store);
}

int32_t esubghz_chat(void)
{
	/* init the GCM and AES tables */
	gcm_initialize();

	int32_t err = -1;

	FURI_LOG_I(APPLICATION_NAME, "Starting...");

	/* allocate necessary structs and buffers */

	ESubGhzChatState *state = malloc(sizeof(ESubGhzChatState));
	if (state == NULL) {
		goto err_alloc;
	}
	memset(state, 0, sizeof(*state));

	state->scene_manager = scene_manager_alloc(
			&esubghz_chat_scene_event_handlers, state);
	if (state->scene_manager == NULL) {
		goto err_alloc_sm;
	}

	state->view_dispatcher = view_dispatcher_alloc();
	if (state->view_dispatcher == NULL) {
		goto err_alloc_vd;
	}

	if (!helper_strings_alloc(state)) {
		goto err_alloc_hs;
	}

	state->text_input = text_input_alloc();
	if (state->text_input == NULL) {
		goto err_alloc_ti;
	}

	if (!chat_box_alloc(state)) {
		goto err_alloc_cb;
	}

	state->subghz_worker = subghz_tx_rx_worker_alloc();
	if (state->subghz_worker == NULL) {
		goto err_alloc_worker;
	}

	/* set the have_read callback of the Sub-GHz worker */
	subghz_tx_rx_worker_set_callback_have_read(state->subghz_worker,
			have_read_cb, state);

	/* enter suppress charge mode */
	furi_hal_power_suppress_charge_enter();

	/* init internal device */
	subghz_devices_init();
	state->subghz_device = subghz_devices_get_by_name(SUBGHZ_DEVICE_CC1101_INT_NAME);

	/* set chat name prefix */
	// TODO: handle escape chars here somehow
	furi_string_printf(state->name_prefix, "\033[0;33m%s\033[0m: ",
			furi_hal_version_get_name_ptr());

	/* get notification record, we use this to make the flipper vibrate */
	/* no error handling here, don't know how */
	state->notification = furi_record_open(RECORD_NOTIFICATION);

	/* hook into the view port's draw and input callbacks */
	state->orig_draw_cb = state->view_dispatcher->view_port->draw_callback;
	state->orig_input_cb = state->view_dispatcher->view_port->input_callback;
	view_port_draw_callback_set(state->view_dispatcher->view_port,
			esubghz_hooked_draw_callback, state);
	view_port_input_callback_set(state->view_dispatcher->view_port,
			esubghz_hooked_input_callback, state);

	view_dispatcher_enable_queue(state->view_dispatcher);

	/* set callbacks for view dispatcher */
	view_dispatcher_set_event_callback_context(state->view_dispatcher, state);
	view_dispatcher_set_custom_event_callback(
			state->view_dispatcher,
			esubghz_chat_custom_event_callback);
	view_dispatcher_set_navigation_event_callback(
			state->view_dispatcher,
			esubghz_chat_navigation_event_callback);
	view_dispatcher_set_tick_event_callback(
			state->view_dispatcher,
			esubghz_chat_tick_event_callback,
			TICK_INTERVAL);

	/* add our two views to the view dispatcher */
	view_dispatcher_add_view(state->view_dispatcher, ESubGhzChatView_Input,
			text_input_get_view(state->text_input));
	view_dispatcher_add_view(state->view_dispatcher, ESubGhzChatView_ChatBox,
			text_box_get_view(state->chat_box));

	/* get the GUI record and attach the view dispatcher to the GUI */
	/* no error handling here, don't know how */
	Gui *gui = furi_record_open(RECORD_GUI);
	view_dispatcher_attach_to_gui(state->view_dispatcher, gui,
			ViewDispatcherTypeFullscreen);

	/* switch to the frequency input scene */
	scene_manager_next_scene(state->scene_manager, ESubGhzChatScene_FreqInput);

	/* run the view dispatcher, this call only returns when we close the
	 * application */
	view_dispatcher_run(state->view_dispatcher);

	/* if it is running, stop the Sub-GHz worker */
	if (subghz_tx_rx_worker_is_running(state->subghz_worker)) {
		subghz_tx_rx_worker_stop(state->subghz_worker);
	}

	err = 0;

	/* close GUI record */
	furi_record_close(RECORD_GUI);

	/* remove our two views from the view dispatcher */
	view_dispatcher_remove_view(state->view_dispatcher,
			ESubGhzChatView_Input);
	view_dispatcher_remove_view(state->view_dispatcher,
			ESubGhzChatView_ChatBox);

	/* close notification record */
	furi_record_close(RECORD_NOTIFICATION);

	/* clear the key and potential password */
	esubghz_chat_explicit_bzero(state->text_input_store,
			sizeof(state->text_input_store));
	esubghz_chat_explicit_bzero(&(state->gcm_ctx), sizeof(state->gcm_ctx));

	/* deinit devices */
	subghz_devices_deinit();

	/* exit suppress charge mode */
	furi_hal_power_suppress_charge_exit();

	/* free everything we allocated */

	subghz_tx_rx_worker_free(state->subghz_worker);

err_alloc_worker:
	chat_box_free(state);

err_alloc_cb:
	text_input_free(state->text_input);

err_alloc_ti:
	helper_strings_free(state);

err_alloc_hs:
	view_dispatcher_free(state->view_dispatcher);

err_alloc_vd:
	scene_manager_free(state->scene_manager);

err_alloc_sm:
	free(state);

err_alloc:
	if (err != 0) {
		FURI_LOG_E(APPLICATION_NAME, "Failed to launch (alloc error)!");
	} else {
		FURI_LOG_I(APPLICATION_NAME, "Clean exit.");
	}

	return err;
}