Give the WebSocket backend some chance of working

This is all untested code.

json-rpc-shell.c

@@ -74,6 +74,13 @@ static struct config_item g_config_table[] =
 
 // --- Main program ------------------------------------------------------------
 
+// HTTP/S and WS/S require significantly different handling.  While for HTTP we
+// can just use the cURL easy interface, with WebSockets it gets a bit more
+// complicated and we implement it all by ourselves.
+//
+// Luckily on a higher level the application doesn't need to bother itself with
+// the details and the backend API can be very simple..
+
 struct app_context;
 
 struct backend_iface
@@ -108,18 +115,32 @@ enum ws_handler_state
 
 struct ws_context
 {
+	// Configuration:
+
 	char *endpoint;                     ///< Endpoint URL
 	struct http_parser_url url;         ///< Parsed URL
+	struct str_vector extra_headers;    ///< Extra headers for the handshake
 
-	enum ws_handler_state state;        ///< State
+	// Events:
-	char *key;                          ///< Key for the current handshake
+
-	struct str *response_buffer;        ///< Buffer for the response
+	bool waiting_for_event;             ///< Running a separate loop to wait?
+	struct error *e;                    ///< Error while waiting for event
+
+	ev_timer timeout_watcher;           ///< Connection timeout watcher
+	struct str *response_buffer;        ///< Buffer for the incoming messages
+
+	// The TCP transport:
 
 	int server_fd;                      ///< Socket FD of the server
 	ev_io read_watcher;                 ///< Server FD read watcher
 	SSL_CTX *ssl_ctx;                   ///< SSL context
 	SSL *ssl;                           ///< SSL connection
 
+	// WebSockets protocol handling:
+
+	enum ws_handler_state state;        ///< State
+	char *key;                          ///< Key for the current handshake
+
 	http_parser hp;                     ///< HTTP parser
 	bool parsing_header_value;          ///< Parsing header value or field?
 	struct str field;                   ///< Field part buffer
@@ -131,14 +152,15 @@ struct ws_context
 
 	enum ws_opcode message_opcode;      ///< Opcode for the current message
 	struct str message_data;            ///< Concatenated message data
-
-	struct str_vector extra_headers;    ///< Extra headers for the handshake
 };
 
 static void
 ws_context_init (struct ws_context *self)
 {
 	memset (self, 0, sizeof *self);
+	ev_timer_init (&self->timeout_watcher, NULL, 0, 0);
+	self->server_fd = -1;
+	ev_io_init (&self->read_watcher, NULL, 0, 0);
 	http_parser_init (&self->hp, HTTP_RESPONSE);
 	str_init (&self->field);
 	str_init (&self->value);
@@ -755,14 +777,15 @@ backend_ws_on_data (struct app_context *ctx, const void *data, size_t len)
 		struct error *e = NULL;
 		if (!backend_ws_finish_handshake (ctx, &e))
 		{
-			print_debug ("WS handshake failed: %s", e->message);
+			print_error ("WS handshake failed: %s", e->message);
 			error_free (e);
 			return false;
 		}
 
+		// Finished the handshake, return to caller
+		// (we run a separate loop to wait for the handshake to finish)
 		self->state = WS_HANDLER_OPEN;
-
+		ev_unloop (EV_DEFAULT_ EVUNLOOP_ONE);
-		// TODO: set the event loop to quit?
 
 		if ((len -= n_parsed))
 			return ws_parser_push (&self->parser,
@@ -775,15 +798,47 @@ backend_ws_on_data (struct app_context *ctx, const void *data, size_t len)
 	if (n_parsed != len || err != HPE_OK)
 	{
 		if (err == HPE_CB_headers_complete)
-			print_debug ("WS handshake failed: %s", "missing `Upgrade' field");
+			print_error ("WS handshake failed: %s", "missing `Upgrade' field");
 		else
-			print_debug ("WS handshake failed: %s",
+			print_error ("WS handshake failed: %s",
 				http_errno_description (err));
 		return false;
 	}
 	return true;
 }
 
+static void
+backend_ws_close_connection (struct app_context *ctx)
+{
+	struct ws_context *self = &ctx->ws;
+	if (self->server_fd == -1)
+		return;
+
+	ev_io_stop (EV_DEFAULT_ &self->read_watcher);
+
+	if (self->ssl)
+	{
+		(void) SSL_shutdown (self->ssl);
+		SSL_free (self->ssl);
+		self->ssl = NULL;
+	}
+
+	xclose (self->server_fd);
+	self->server_fd = -1;
+
+	self->state = WS_HANDLER_CLOSED;
+
+	// That would have no way of succeeding
+	// XXX: what if we're waiting for the close?
+	if (self->waiting_for_event)
+	{
+		if (!self->e)
+			error_set (&self->e, "unexpected connection close");
+
+		ev_unloop (EV_DEFAULT_ EVUNLOOP_ONE);
+	}
+}
+
 static void
 backend_ws_on_fd_ready (EV_P_ ev_io *handle, int revents)
 {
@@ -793,44 +848,46 @@ backend_ws_on_fd_ready (EV_P_ ev_io *handle, int revents)
 	struct app_context *ctx = handle->data;
 	struct ws_context *self = &ctx->ws;
 
-	(void) set_blocking (self->server_fd, false);
-
 	enum ws_read_result (*fill_buffer)(struct app_context *, void *, size_t *)
 		= self->ssl
 		? backend_ws_fill_read_buffer_tls
 		: backend_ws_fill_read_buffer;
-	bool disconnected = false;
+	bool close_connection = false;
 
 	uint8_t buf[8192];
 	while (true)
 	{
+		// Try to read some data in a non-blocking manner
 		size_t n_read = sizeof buf;
-		switch (fill_buffer (ctx, buf, &n_read))
+		(void) set_blocking (self->server_fd, false);
+		enum ws_read_result result = fill_buffer (ctx, buf, &n_read);
+		(void) set_blocking (self->server_fd, true);
+
+		switch (result)
 		{
 		case WS_READ_AGAIN:
 			goto end;
 		case WS_READ_ERROR:
 			print_error ("reading from the server failed");
-			disconnected = true;
+			close_connection = true;
 			goto end;
 		case WS_READ_EOF:
 			print_status ("the server closed the connection");
-			disconnected = true;
+			close_connection = true;
 			goto end;
 		case WS_READ_OK:
-			// XXX: this is a bit ugly
+			if (backend_ws_on_data (ctx, buf, n_read))
-			(void) set_blocking (self->server_fd, true);
+				break;
-			// TODO: use the return value
+
-			backend_ws_on_data (ctx, buf, n_read);
+			// XXX: maybe we should wait until we receive an EOF
-			(void) set_blocking (self->server_fd, false);
+			close_connection = true;
-			break;
+			goto end;
 		}
 	}
 
 end:
-	(void) set_blocking (self->server_fd, true);
+	if (close_connection)
-	if (disconnected)
+		backend_ws_close_connection (ctx);
-		;  // TODO
 }
 
 static bool
@@ -855,8 +912,6 @@ backend_ws_write (struct app_context *ctx, const void *data, size_t len)
 		print_debug ("%s: %s: %s", __func__, "write", strerror (errno));
 		result = false;
 	}
-
-	// TODO: destroy the connection on failure?
 	return result;
 }
 
@@ -1012,7 +1067,7 @@ backend_ws_send_message (struct app_context *ctx,
 	return result;
 }
 
-static void
+static bool
 backend_ws_send_control (struct app_context *ctx,
 	enum ws_opcode opcode, const void *data, size_t len)
 {
@@ -1023,22 +1078,22 @@ backend_ws_send_control (struct app_context *ctx,
 		len = WS_MAX_CONTROL_PAYLOAD_LEN;
 	}
 
-	backend_ws_send_control (ctx, opcode, data, len);
+	return backend_ws_send_message (ctx, opcode, data, len);
 }
 
-static void
+static bool
 backend_ws_fail (struct app_context *ctx, enum ws_status reason)
 {
-	uint8_t payload[2] = { reason << 8, reason };
+	struct ws_context *self = &ctx->ws;
-	backend_ws_send_control (ctx, WS_OPCODE_CLOSE, payload, sizeof payload);
 
-	// TODO: set the close timer, ignore all further incoming input (either set
+	uint8_t payload[2] = { reason << 8, reason };
-	//   some flag for the case that we're in the middle of backend_ws_push(),
+	(void) backend_ws_send_control (ctx, WS_OPCODE_CLOSE,
-	//   and/or add a mechanism to stop the caller from polling the socket for
+		payload, sizeof payload);
-	//   reads).
+
-	// TODO: set the state to FAILED (not CLOSED as that means the TCP
+	// The caller should immediately proceed to close the TCP connection,
-	//   connection is closed) and wait until all is sent?
+	// e.g. by returning false from a handler
-	// TODO: make sure we don't send pings after the close
+	self->state = WS_HANDLER_CLOSING;
+	return false;
 }
 
 static bool
@@ -1057,37 +1112,66 @@ backend_ws_on_frame_header (void *user_data, const struct ws_parser *parser)
 	 || (!ws_is_control_frame (parser->opcode) &&
 		(self->expecting_continuation && parser->opcode != WS_OPCODE_CONT))
 	 || parser->payload_len >= 0x8000000000000000ULL)
-		backend_ws_fail (ctx, WS_STATUS_PROTOCOL_ERROR);
+		return backend_ws_fail (ctx, WS_STATUS_PROTOCOL_ERROR);
 	else if (parser->payload_len > BACKEND_WS_MAX_PAYLOAD_LEN)
-		backend_ws_fail (ctx, WS_STATUS_MESSAGE_TOO_BIG);
+		return backend_ws_fail (ctx, WS_STATUS_MESSAGE_TOO_BIG);
-	else
+	return true;
-		return true;
+}
-	return false;
+
+static bool
+backend_ws_finish_closing_handshake
+	(struct app_context *ctx, const struct ws_parser *parser)
+{
+	struct str reason;
+	str_init (&reason);
+
+	if (parser->payload_len >= 2)
+	{
+		struct msg_unpacker unpacker;
+		msg_unpacker_init (&unpacker, parser->input.str, parser->payload_len);
+
+		uint16_t status_code;
+		msg_unpacker_u16 (&unpacker, &status_code);
+		print_debug ("close status code: %d", status_code);
+
+		str_append_data (&reason,
+			parser->input.str + 2, parser->payload_len - 2);
+	}
+
+	char *s = iconv_xstrdup (ctx->term_from_utf8,
+		reason.str, reason.len, NULL);
+	print_status ("server closed the connection (%s)", s);
+	str_free (&reason);
+	free (s);
+
+	return backend_ws_send_control (ctx, WS_OPCODE_CLOSE,
+		parser->input.str, parser->payload_len);
 }
 
 static bool
 backend_ws_on_control_frame
 	(struct app_context *ctx, const struct ws_parser *parser)
 {
+	struct ws_context *self = &ctx->ws;
 	switch (parser->opcode)
 	{
 	case WS_OPCODE_CLOSE:
-		// TODO: confirm the close
+		// We've received an unsolicited server close
-		// TODO: change the state to CLOSING
+		if (self->state != WS_HANDLER_CLOSING)
-		// TODO: call "on_close"
+			(void) backend_ws_finish_closing_handshake (ctx, parser);
-		// NOTE: the reason is an empty string if omitted
+
-		break;
+		return false;
 	case WS_OPCODE_PING:
-		backend_ws_send_control (ctx, WS_OPCODE_PONG,
+		if (!backend_ws_send_control (ctx, WS_OPCODE_PONG,
-			parser->input.str, parser->payload_len);
+			parser->input.str, parser->payload_len))
+			return false;
 		break;
 	case WS_OPCODE_PONG:
 		// Not sending any pings but w/e
 		break;
 	default:
 		// Unknown control frame
-		backend_ws_fail (ctx, WS_STATUS_PROTOCOL_ERROR);
+		return backend_ws_fail (ctx, WS_STATUS_PROTOCOL_ERROR);
-		return false;
 	}
 	return true;
 }
@@ -1099,19 +1183,16 @@ backend_ws_on_message (struct app_context *ctx,
 	struct ws_context *self = &ctx->ws;
 
 	if (type != WS_OPCODE_TEXT)
-	{
+		return backend_ws_fail (ctx, WS_STATUS_UNSUPPORTED_DATA);
-		backend_ws_fail (ctx, WS_STATUS_UNSUPPORTED_DATA);
-		return false;
-	}
 
-	if (!self->response_buffer)
+	if (!self->waiting_for_event || !self->response_buffer)
 	{
-		// TODO: warn about unexpected messages
+		print_warning ("unexpected message received");
 		return true;
 	}
 
 	str_append_data (self->response_buffer, data, len);
-	// TODO: exit the event loop
+	ev_unloop (EV_DEFAULT_ EVUNLOOP_ONE);
 	return true;
 }
 
@@ -1126,10 +1207,7 @@ backend_ws_on_frame (void *user_data, const struct ws_parser *parser)
 	// TODO: do this rather in "on_frame_header"
 	if (self->message_data.len + parser->payload_len
 		> BACKEND_WS_MAX_PAYLOAD_LEN)
-	{
+		return backend_ws_fail (ctx, WS_STATUS_MESSAGE_TOO_BIG);
-		backend_ws_fail (ctx, WS_STATUS_MESSAGE_TOO_BIG);
-		return false;
-	}
 
 	if (!self->expecting_continuation)
 		self->message_opcode = parser->opcode;
@@ -1143,10 +1221,7 @@ backend_ws_on_frame (void *user_data, const struct ws_parser *parser)
 
 	if (self->message_opcode == WS_OPCODE_TEXT
 	 && !utf8_validate (self->parser.input.str, self->parser.input.len))
-	{
+		return backend_ws_fail (ctx, WS_STATUS_INVALID_PAYLOAD_DATA);
-		backend_ws_fail (ctx, WS_STATUS_INVALID_PAYLOAD_DATA);
-		return false;
-	}
 
 	bool result = backend_ws_on_message (ctx, self->message_opcode,
 		self->message_data.str, self->message_data.len);
@@ -1154,6 +1229,20 @@ backend_ws_on_frame (void *user_data, const struct ws_parser *parser)
 	return result;
 }
 
+static void
+backend_ws_on_connection_timeout (EV_P_ ev_io *handle, int revents)
+{
+	(void) loop;
+	(void) revents;
+
+	struct app_context *ctx = handle->data;
+	struct ws_context *self = &ctx->ws;
+
+	hard_assert (self->waiting_for_event);
+	error_set (&self->e, "connection timeout");
+	backend_ws_close_connection (ctx);
+}
+
 static bool
 backend_ws_connect (struct app_context *ctx, struct error **e)
 {
@@ -1223,7 +1312,7 @@ backend_ws_connect (struct app_context *ctx, struct error **e)
 	http_parser_init (&self->hp, HTTP_RESPONSE);
 	str_reset (&self->field);
 	str_reset (&self->value);
-	// TODO: write a function to free self->headers and call it here
+	str_map_clear (&self->headers);
 	ws_parser_free (&self->parser);
 	ws_parser_init (&self->parser);
 	self->parser.on_frame_header = backend_ws_on_frame_header;
@@ -1235,10 +1324,28 @@ backend_ws_connect (struct app_context *ctx, struct error **e)
 	self->read_watcher.data = ctx;
 	ev_io_start (EV_DEFAULT_ &self->read_watcher);
 
-	// TODO: set a timeout timer
+	// XXX: we should do everything non-blocking and include establishing
-	// TODO: run an event loop to process the handshake response
+	//   the TCP connection in the timeout, but that requires a rewrite.
+	//   As it is, this isn't really too useful.
+	ev_timer_init (&self->timeout_watcher,
+		backend_ws_on_connection_timeout, 30, 0);
 
-	result = true;
+	// Run an event loop to process the handshake
+	ev_timer_start (EV_DEFAULT_ &self->timeout_watcher);
+	self->waiting_for_event = true;
+
+	ev_loop (EV_DEFAULT_ 0);
+
+	self->waiting_for_event = false;
+	ev_timer_stop (EV_DEFAULT_ &self->timeout_watcher);
+
+	if (self->e)
+	{
+		error_propagate (e, self->e);
+		self->e = NULL;
+	}
+	else
+		result = true;
 
 fail_2:
 	if (!result)
@@ -1269,16 +1376,28 @@ backend_ws_make_call (struct app_context *ctx,
 		if (backend_ws_send_message (ctx,
 			WS_OPCODE_TEXT, request, strlen (request)))
 			break;
-		print_status ("connection failed");
+		print_status ("connection failed, reconnecting");
 		if (!backend_ws_connect (ctx, e))
 			return false;
 	}
 
 	if (expect_content)
 	{
+		// Run an event loop to retrieve the response
 		self->response_buffer = buf;
-		// TODO: run an event loop to retrieve the answer into "buf"
+		self->waiting_for_event = true;
+
+		ev_loop (EV_DEFAULT_ 0);
+
+		self->waiting_for_event = false;
 		self->response_buffer = NULL;
+
+		if (self->e)
+		{
+			error_propagate (e, self->e);
+			self->e = NULL;
+			return false;
+		}
 	}
 	return true;
 }
@@ -1286,7 +1405,26 @@ backend_ws_make_call (struct app_context *ctx,
 static void
 backend_ws_destroy (struct app_context *ctx)
 {
-	// TODO
+	struct ws_context *self = &ctx->ws;
+
+	// TODO: maybe attempt a graceful shutdown, but for that there should
+	//   probably be another backend method that runs an event loop
+	if (self->server_fd != -1)
+		backend_ws_close_connection (ctx);
+
+	free (self->endpoint);
+	str_vector_free (&self->extra_headers);
+	if (self->e)
+		error_free (self->e);
+	ev_timer_stop (EV_DEFAULT_ &self->timeout_watcher);
+	if (self->ssl_ctx)
+		SSL_CTX_free (self->ssl_ctx);
+	free (self->key);
+	str_free (&self->field);
+	str_free (&self->value);
+	str_map_free (&self->headers);
+	ws_parser_free (&self->parser);
+	str_free (&self->message_data);
 }
 
 static struct backend_iface g_backend_ws =