Woo we can draw over the network now

autistdraw.c

@@ -39,6 +39,17 @@
 
 #define BITMAP_BLOCK_SIZE  50           ///< Step for extending bitmap size
 
+#define PROTOCOL_VERSION    1           ///< Network protocol version
+
+enum
+{
+	MESSAGE_HELLO,                      ///< Server/client hello
+	MESSAGE_GET_BITMAP,                 ///< Request bitmap data
+	MESSAGE_PUT_POINT,                  ///< Request to place a point
+
+	MESSAGE_COUNT                       ///< Total number of messages
+};
+
 typedef enum network_mode network_mode_t;
 enum network_mode
 {
@@ -47,12 +58,20 @@ enum network_mode
 	NETWORK_MODE_CLIENT                 ///< We're a client
 };
 
+typedef struct write_req write_req_t;
+struct write_req
+{
+	uv_write_t req;                     ///< libuv write request
+	uv_buf_t buf;                       ///< The data to be written
+};
+
 typedef struct client client_t;
 struct client
 {
 	LIST_HEADER (client_t)
 
 	uv_tcp_t handle;                    ///< TCP connection handle
+	struct msg_reader msg_reader;       ///< Client message reader
 };
 
 typedef struct app_context app_context_t;
@@ -70,6 +89,7 @@ struct app_context
 
 	// Client:
 	uv_tcp_t server_fd;                 ///< Connection to the server
+	struct msg_reader msg_reader;       ///< Server message reader
 
 	// Server:
 	uv_tcp_t listen_fd;                 ///< Listening FD
@@ -98,20 +118,14 @@ struct app_context
 	uint8_t current_color_right;        ///< Right mouse button color
 };
 
+static void remove_client (app_context_t *app, client_t *client);
+static void on_server_disconnected (app_context_t *app);
+
 static void
 app_init (app_context_t *self)
 {
 	memset (self, 0, sizeof *self);
-}
+	msg_reader_init (&self->msg_reader);
-
-static void
-remove_client (app_context_t *app, client_t *client)
-{
-	// TODO: cancel any write requests?
-	// XXX: should we unref it?
-	uv_close ((uv_handle_t *) &client->handle, NULL);
-	LIST_UNLINK (app->clients, client);
-	free (client);
 }
 
 static void
@@ -120,11 +134,150 @@ app_free (app_context_t *self)
 	if (self->tk)
 		termo_destroy (self->tk);
 	while (self->clients)
+		// XXX: we probably shouldn't do this from here
 		remove_client (self, self->clients);
 
 	free (self->bitmap);
+	msg_reader_free (&self->msg_reader);
 }
 
+// --- Server-client messaging -------------------------------------------------
+
+static write_req_t *
+flush_writer (struct msg_writer *writer)
+{
+	size_t len;
+	void *data = msg_writer_flush (writer, &len);
+	write_req_t *req = xcalloc (1, sizeof *req);
+	req->buf = uv_buf_init (data, len);
+	return req;
+}
+
+static void
+on_data_written_to_client (uv_write_t *req, int status)
+{
+	write_req_t *wr = (write_req_t *) req;
+	app_context_t *app = req->handle->loop->data;
+	client_t *client = req->data;
+
+	if (status)
+		// Write failed
+		remove_client (app, client);
+
+	free (wr->buf.base);
+	free (wr);
+}
+
+static void
+flush_writer_to_client (struct msg_writer *writer, client_t *client)
+{
+	write_req_t *wr = flush_writer (writer);
+	wr->req.data = client;
+	(void) uv_write (&wr->req, (uv_stream_t *) &client->handle,
+		&wr->buf, 1, on_data_written_to_client);
+	// XXX: should we put the request on a list so that we can get rid of it?
+}
+
+static void
+on_data_written_to_server (uv_write_t *req, int status)
+{
+	write_req_t *wr = (write_req_t *) req;
+	app_context_t *app = req->handle->loop->data;
+
+	if (status)
+		// Write failed
+		on_server_disconnected (app);
+
+	free (wr->buf.base);
+	free (wr);
+}
+
+static void
+flush_writer_to_server (struct msg_writer *writer, app_context_t *app)
+{
+	write_req_t *wr = flush_writer (writer);
+	(void) uv_write (&wr->req, (uv_stream_t *) &app->server_fd,
+		&wr->buf, 1, on_data_written_to_server);
+	// XXX: should we put the request on a list so that we can get rid of it?
+}
+
+static void
+send_draw_point_response (client_t *client, int x, int y, uint8_t color)
+{
+	struct msg_writer writer;
+	msg_writer_init (&writer);
+	msg_writer_u8 (&writer, MESSAGE_PUT_POINT);
+	msg_writer_i32 (&writer, x);
+	msg_writer_i32 (&writer, y);
+	msg_writer_u8 (&writer, color);
+
+	flush_writer_to_client (&writer, client);
+}
+
+static void
+send_draw_point_request (app_context_t *app, int x, int y, uint8_t color)
+{
+	struct msg_writer writer;
+	msg_writer_init (&writer);
+	msg_writer_u8 (&writer, MESSAGE_PUT_POINT);
+	msg_writer_i32 (&writer, x);
+	msg_writer_i32 (&writer, y);
+	msg_writer_u8 (&writer, color);
+
+	flush_writer_to_server (&writer, app);
+}
+
+static void
+send_hello_request (app_context_t *app)
+{
+	struct msg_writer writer;
+	msg_writer_init (&writer);
+	msg_writer_u8 (&writer, MESSAGE_HELLO);
+	msg_writer_u8 (&writer, PROTOCOL_VERSION);
+
+	flush_writer_to_server (&writer, app);
+}
+
+static void
+send_hello_response (client_t *client)
+{
+	struct msg_writer writer;
+	msg_writer_init (&writer);
+	msg_writer_u8 (&writer, MESSAGE_HELLO);
+	msg_writer_u8 (&writer, PROTOCOL_VERSION);
+
+	flush_writer_to_client (&writer, client);
+}
+
+static void
+send_get_bitmap_request (app_context_t *app)
+{
+	struct msg_writer writer;
+	msg_writer_init (&writer);
+	msg_writer_u8 (&writer, MESSAGE_GET_BITMAP);
+
+	flush_writer_to_server (&writer, app);
+}
+
+static void
+send_get_bitmap_response (client_t *client, app_context_t *app)
+{
+	struct msg_writer writer;
+	msg_writer_init (&writer);
+	msg_writer_u8 (&writer, MESSAGE_GET_BITMAP);
+	msg_writer_i32 (&writer, app->bitmap_x);
+	msg_writer_i32 (&writer, app->bitmap_y);
+	msg_writer_u64 (&writer, app->bitmap_w);
+	msg_writer_u64 (&writer, app->bitmap_h);
+
+	msg_writer_blob (&writer, app->bitmap,
+		app->bitmap_w * app->bitmap_h * sizeof *app->bitmap);
+
+	flush_writer_to_client (&writer, client);
+}
+
+// --- Server-client messaging -------------------------------------------------
+
 static void
 display (const char *format, ...)
 {
@@ -306,6 +459,11 @@ draw_point (app_context_t *app, int x, int y, uint8_t color)
 		addch (app->palette[color]);
 		refresh ();
 	}
+
+	// Broadcast the clients about the event
+	if (app->mode == NETWORK_MODE_SERVER)
+		for (client_t *iter = app->clients; iter; iter = iter->next)
+			send_draw_point_response (iter, x, y, color);
 }
 
 // --- Exports -----------------------------------------------------------------
@@ -538,7 +696,8 @@ on_key (app_context_t *app, termo_key_t *key)
 	if (event != TERMO_MOUSE_PRESS && event != TERMO_MOUSE_DRAG)
 		return true;
 
-	if (button == 2)
+	// Middle mouse button, or Ctrl + left mouse button, moves the canvas
+	if (button == 2 || (button == 1 && key->modifiers == TERMO_KEYMOD_CTRL))
 	{
 		if (event == TERMO_MOUSE_DRAG)
 		{
@@ -568,7 +727,12 @@ on_key (app_context_t *app, termo_key_t *key)
 	int canvas_y = app->corner_y + screen_y - TOP_BAR_CUTOFF;
 
 	if (screen_y >= TOP_BAR_CUTOFF)
+	{
+		if (app->mode == NETWORK_MODE_CLIENT)
+			send_draw_point_request (app, canvas_x, canvas_y, *color);
+		else
 			draw_point (app, canvas_x, canvas_y, *color);
+	}
 	else if (screen_y > 0 && event != TERMO_MOUSE_DRAG)
 	{
 		int pair = (float) screen_x / COLS * PALETTE_WIDTH;
@@ -650,14 +814,13 @@ app_uv_allocator (uv_handle_t *handle, size_t suggested_size, uv_buf_t *buf)
 	buf->len = sizeof app->read_buf;
 }
 
-static void
+// --- Client-specific stuff ---------------------------------------------------
-on_server_data (uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf)
-{
-	(void) buf;
 
-	app_context_t *app = stream->loop->data;
+typedef void (*server_handler_fn) (app_context_t *, struct msg_unpacker *);
-	if (nread == UV_EOF || nread < 0)
+
-	{
+static void
+on_server_disconnected (app_context_t *app)
+{
 	// TODO: cancel any write requests?
 	// XXX: should we unref it?
 	uv_close ((uv_handle_t *) &app->server_fd, NULL);
@@ -668,26 +831,214 @@ on_server_data (uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf)
 	// Let the user save the picture at least.
 	// Also prevents us from trying to use the dead server handle.
 	app->mode = NETWORK_MODE_STANDALONE;
+}
+
+static void
+on_server_hello (app_context_t *app, struct msg_unpacker *unpacker)
+{
+	(void) app;
+
+	uint8_t version;
+	if (!msg_unpacker_u8 (unpacker, &version))
+		return;
+
+	if (version != PROTOCOL_VERSION)
+		// XXX: possibly incompatible version, disconnect?
+		return;
+}
+
+static void
+on_server_get_bitmap (app_context_t *app, struct msg_unpacker *unpacker)
+{
+	int32_t x, y;
+	uint64_t w, h;
+	if (!msg_unpacker_i32 (unpacker, &x)
+	 || !msg_unpacker_i32 (unpacker, &y)
+	 || !msg_unpacker_u64 (unpacker, &w)
+	 || !msg_unpacker_u64 (unpacker, &h))
+		return;
+
+	// TODO: employ at least some RLE encoding
+	size_t size = w * h * sizeof *app->bitmap;
+	if ((h && w > SIZE_MAX / h) || w > SIZE_MAX || h > SIZE_MAX)
+		return;
+
+	const void *data;
+	if (!msg_unpacker_blob (unpacker, &data, size))
+		return;
+
+	free (app->bitmap);
+	app->bitmap = memcpy (xcalloc (1, size), data, size);
+	app->bitmap_x = x;
+	app->bitmap_y = y;
+	app->bitmap_w = w;
+	app->bitmap_h = h;
+
+	redraw_canvas (app);
+}
+
+static void
+on_server_put_point (app_context_t *app, struct msg_unpacker *unpacker)
+{
+	int32_t x, y;
+	uint8_t color;
+
+	if (!msg_unpacker_i32 (unpacker, &x)
+	 || !msg_unpacker_i32 (unpacker, &y)
+	 || !msg_unpacker_u8 (unpacker, &color))
+		return;
+
+	draw_point (app, x, y, color);
+}
+
+static void
+on_server_data (uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf)
+{
+	app_context_t *app = stream->loop->data;
+	if (nread == UV_EOF || nread < 0)
+	{
+		on_server_disconnected (app);
 		return;
 	}
 
-	// TODO: process the data
+	msg_reader_feed (&app->msg_reader, buf->base, nread);
+
+	static const server_handler_fn handlers[MESSAGE_COUNT] =
+	{
+		[MESSAGE_HELLO]      = on_server_hello,
+		[MESSAGE_GET_BITMAP] = on_server_get_bitmap,
+		[MESSAGE_PUT_POINT]  = on_server_put_point,
+	};
+
+	void *msg;
+	size_t len;
+	while ((msg = msg_reader_get (&app->msg_reader, &len)))
+	{
+		struct msg_unpacker unpacker;
+		msg_unpacker_init (&unpacker, msg, len);
+
+		uint8_t type;
+		if (!msg_unpacker_u8 (&unpacker, &type)
+		 || type >= MESSAGE_COUNT)
+			// XXX: unknown message, disconnect?
+			continue;
+
+		server_handler_fn handler = handlers[type];
+		if (!handler)
+			// XXX: unknown message, disconnect?
+			continue;
+
+		handler (app, &unpacker);
+
+		if (msg_unpacker_get_available (&unpacker) > 0)
+			// XXX: overlong message, disconnect?
+			continue;
+	}
+}
+
+// --- Server-specific stuff ---------------------------------------------------
+
+typedef bool (*client_handler_fn)
+	(app_context_t *, client_t *, struct msg_unpacker *);
+
+static void
+remove_client (app_context_t *app, client_t *client)
+{
+	// TODO: cancel any write requests?
+	// XXX: should we unref it?
+	uv_close ((uv_handle_t *) &client->handle, NULL);
+	LIST_UNLINK (app->clients, client);
+	msg_reader_free (&client->msg_reader);
+	free (client);
+}
+
+static bool
+on_client_hello (app_context_t *app, client_t *client,
+	struct msg_unpacker *unpacker)
+{
+	(void) app;
+
+	uint8_t version;
+	if (!msg_unpacker_u8 (unpacker, &version)
+	 || version != PROTOCOL_VERSION)
+		// Nope, I don't like you
+		return false;
+
+	send_hello_response (client);
+	return true;
+}
+
+static bool
+on_client_get_bitmap (app_context_t *app, client_t *client,
+	struct msg_unpacker *unpacker)
+{
+	(void) unpacker;
+
+	send_get_bitmap_response (client, app);
+	return true;
+}
+
+static bool
+on_client_put_point (app_context_t *app, client_t *client,
+	struct msg_unpacker *unpacker)
+{
+	(void) client;
+
+	int32_t x, y;
+	uint8_t color;
+	if (!msg_unpacker_i32 (unpacker, &x)
+	 || !msg_unpacker_i32 (unpacker, &y)
+	 || !msg_unpacker_u8 (unpacker, &color))
+		return false;
+
+	// The function takes care of broadcasting to all the other clients,
+	// as well as back to the original sender
+	draw_point (app, x, y, color);
+	return true;
 }
 
 static void
 on_client_data (uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf)
 {
-	(void) buf;
-
 	app_context_t *app = stream->loop->data;
 	client_t *client = stream->data;
 	if (nread == UV_EOF || nread < 0)
-	{
+		goto disconnect;  // Connection closed or error
-		remove_client (app, client);
-		return;
-	}
 
-	// TODO: process the data
+	msg_reader_feed (&client->msg_reader, buf->base, nread);
+
+	static const client_handler_fn handlers[MESSAGE_COUNT] =
+	{
+		[MESSAGE_HELLO]      = on_client_hello,
+		[MESSAGE_GET_BITMAP] = on_client_get_bitmap,
+		[MESSAGE_PUT_POINT]  = on_client_put_point,
+	};
+
+	void *msg;
+	size_t len;
+	while ((msg = msg_reader_get (&client->msg_reader, &len)))
+	{
+		struct msg_unpacker unpacker;
+		msg_unpacker_init (&unpacker, msg, len);
+
+		uint8_t type;
+		if (!msg_unpacker_u8 (&unpacker, &type))
+			goto disconnect;  // Invalid message
+		if (type >= MESSAGE_COUNT)
+			goto disconnect;  // Unknown message
+
+		client_handler_fn handler = handlers[type];
+		if (!handler)
+			goto disconnect;  // Unknown message
+		if (!handler (app, client, &unpacker))
+			goto disconnect;  // Invalid message
+		if (msg_unpacker_get_available (&unpacker) > 0)
+			goto disconnect;  // Overlong message data
+	}
+	return;
+
+disconnect:
+	remove_client (app, client);
 }
 
 static void
@@ -708,6 +1059,7 @@ on_new_client (uv_stream_t *server, int status)
 		goto free_handle;
 
 	client->handle.data = client;
+	msg_reader_init (&client->msg_reader);
 	LIST_PREPEND (app->clients, client);
 	return;
 
@@ -907,6 +1259,9 @@ initialize_client (app_context_t *app, struct addrinfo *address)
 			"error", "initialization failed", uv_strerror (err));
 		exit (EXIT_FAILURE);
 	}
+
+	send_hello_request (app);
+	send_get_bitmap_request (app);
 }
 
 static void

utils.c

@@ -216,6 +216,20 @@ str_append_printf (struct str *self, const char *fmt, ...)
 	return size;
 }
 
+static void
+str_remove_slice (struct str *self, size_t start, size_t length)
+{
+	size_t end = start + length;
+	if (end > self->len)
+		end = self->len;
+	memmove (self->str + start, self->str + end, self->len - end);
+	self->str[self->len -= length] = '\0';
+
+	// Shrink the string if the allocation becomes way too large
+	if (self->alloc >= STR_SHRINK_THRESHOLD && self->len < (self->alloc >> 2))
+		self->str = xrealloc (self->str, self->alloc >>= 2);
+}
+
 // --- Utilities ---------------------------------------------------------------
 
 static bool
@@ -270,6 +284,208 @@ xstrtoul (unsigned long *out, const char *s, int base)
 	return errno == 0 && !*end && end != s;
 }
 
+// --- Message reader ----------------------------------------------------------
+
+struct msg_reader
+{
+	struct str buf;                     ///< Input buffer
+	uint64_t offset;                    ///< Current offset in the buffer
+};
+
+static void
+msg_reader_init (struct msg_reader *self)
+{
+	str_init (&self->buf);
+	self->offset = 0;
+}
+
+static void
+msg_reader_free (struct msg_reader *self)
+{
+	str_free (&self->buf);
+}
+
+static void
+msg_reader_compact (struct msg_reader *self)
+{
+	str_remove_slice (&self->buf, 0, self->offset);
+	self->offset = 0;
+}
+
+static void
+msg_reader_feed (struct msg_reader *self, const void *data, size_t len)
+{
+	// TODO: have some mechanism to prevent flooding
+	msg_reader_compact (self);
+	str_append_data (&self->buf, data, len);
+}
+
+static void *
+msg_reader_get (struct msg_reader *self, size_t *len)
+{
+	// Try to read in the length of the message
+	if (self->offset + sizeof (uint64_t) > self->buf.len)
+		return NULL;
+
+	uint8_t *x = (uint8_t *) self->buf.str + self->offset;
+	uint64_t msg_len
+		= (uint64_t) x[0] << 56 | (uint64_t) x[1] << 48
+		| (uint64_t) x[2] << 40 | (uint64_t) x[3] << 32
+		| (uint64_t) x[4] << 24 | (uint64_t) x[5] << 16
+		| (uint64_t) x[6] << 8  | (uint64_t) x[7];
+
+	if (msg_len < sizeof msg_len)
+	{
+		// The message is shorter than its header
+		// TODO: have some mechanism to report errors
+		return NULL;
+	}
+
+	if (self->offset + msg_len < self->offset)
+	{
+		// Trying to read an insane amount of data but whatever
+		msg_reader_compact (self);
+		return NULL;
+	}
+
+	// Check if we've got the full message in the buffer and return it
+	if (self->offset + msg_len > self->buf.len)
+		return NULL;
+
+	// We have to subtract the header from the reported length
+	void *data = self->buf.str + self->offset + sizeof msg_len;
+	self->offset += msg_len;
+	*len = msg_len - sizeof msg_len;
+	return data;
+}
+
+// --- Message unpacker --------------------------------------------------------
+
+struct msg_unpacker
+{
+	const char *data;
+	size_t offset;
+	size_t len;
+};
+
+static void
+msg_unpacker_init (struct msg_unpacker *self, const void *data, size_t len)
+{
+	self->data = data;
+	self->len = len;
+	self->offset = 0;
+}
+
+static size_t
+msg_unpacker_get_available (struct msg_unpacker *self)
+{
+	return self->len - self->offset;
+}
+
+static bool
+msg_unpacker_blob (struct msg_unpacker *self, const void **data, size_t len)
+{
+	if (self->len - self->offset < len)
+		return false;
+	*data = self->data + self->offset;
+	self->offset += len;
+	return true;
+}
+
+#define UNPACKER_INT_BEGIN                                                     \
+	if (self->len - self->offset < sizeof *value)                              \
+		return false;                                                          \
+	uint8_t *x = (uint8_t *) self->data + self->offset;                        \
+	self->offset += sizeof *value;
+
+static bool
+msg_unpacker_u8 (struct msg_unpacker *self, uint8_t *value)
+{
+	UNPACKER_INT_BEGIN
+	*value = x[0];
+	return true;
+}
+
+static bool
+msg_unpacker_i32 (struct msg_unpacker *self, int32_t *value)
+{
+	UNPACKER_INT_BEGIN
+	*value
+		= (uint32_t) x[0] << 24 | (uint32_t) x[1] << 16
+		| (uint32_t) x[2] << 8  | (uint32_t) x[3];
+	return true;
+}
+
+static bool
+msg_unpacker_u64 (struct msg_unpacker *self, uint64_t *value)
+{
+	UNPACKER_INT_BEGIN
+	*value
+		= (uint64_t) x[0] << 56 | (uint64_t) x[1] << 48
+		| (uint64_t) x[2] << 40 | (uint64_t) x[3] << 32
+		| (uint64_t) x[4] << 24 | (uint64_t) x[5] << 16
+		| (uint64_t) x[6] << 8  | (uint64_t) x[7];
+	return true;
+}
+
+#undef UNPACKER_INT_BEGIN
+
+// --- Message packer and writer -----------------------------------------------
+
+struct msg_writer
+{
+	struct str buf;                     ///< Holds the message data
+};
+
+static void
+msg_writer_init (struct msg_writer *self)
+{
+	str_init (&self->buf);
+	// Placeholder for message length
+	str_append_data (&self->buf, "\x00\x00\x00\x00" "\x00\x00\x00\x00", 8);
+}
+
+static void
+msg_writer_blob (struct msg_writer *self, const void *data, size_t len)
+{
+	str_append_data (&self->buf, data, len);
+}
+
+static void
+msg_writer_u8 (struct msg_writer *self, uint8_t x)
+{
+	str_append_data (&self->buf, &x, 1);
+}
+
+static void
+msg_writer_i32 (struct msg_writer *self, int32_t x)
+{
+	uint32_t u = x;
+	uint8_t tmp[4] = { u >> 24, u >> 16, u >> 8, u };
+	str_append_data (&self->buf, tmp, sizeof tmp);
+}
+
+static void
+msg_writer_u64 (struct msg_writer *self, uint64_t x)
+{
+	uint8_t tmp[8] =
+		{ x >> 56, x >> 48, x >> 40, x >> 32, x >> 24, x >> 16, x >> 8, x };
+	str_append_data (&self->buf, tmp, sizeof tmp);
+}
+
+static void *
+msg_writer_flush (struct msg_writer *self, size_t *len)
+{
+	// Update the message length
+	uint64_t x = self->buf.len;
+	uint8_t tmp[8] =
+		{ x >> 56, x >> 48, x >> 40, x >> 32, x >> 24, x >> 16, x >> 8, x };
+	memcpy (self->buf.str, tmp, sizeof tmp);
+
+	*len = x;
+	return str_steal (&self->buf);
+}
+
 // --- Option handler ----------------------------------------------------------
 
 // Simple wrapper for the getopt_long API to make it easier to use and maintain.