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//! Generic WebSocket message stream. pub mod frame; mod message; pub use self::frame::CloseFrame; pub use self::message::Message; use log::*; use std::collections::VecDeque; use std::io::{ErrorKind as IoErrorKind, Read, Write}; use std::mem::replace; use self::frame::coding::{CloseCode, Control as OpCtl, Data as OpData, OpCode}; use self::frame::{Frame, FrameCodec}; use self::message::{IncompleteMessage, IncompleteMessageType}; use crate::error::{Error, Result}; use crate::util::NonBlockingResult; /// Indicates a Client or Server role of the websocket #[derive(Debug, Clone, Copy, PartialEq, Eq)] pub enum Role { /// This socket is a server Server, /// This socket is a client Client, } /// The configuration for WebSocket connection. #[derive(Debug, Clone, Copy)] pub struct WebSocketConfig { /// The size of the send queue. You can use it to turn on/off the backpressure features. `None` /// means here that the size of the queue is unlimited. The default value is the unlimited /// queue. pub max_send_queue: Option<usize>, /// The maximum size of a message. `None` means no size limit. The default value is 64 megabytes /// which should be reasonably big for all normal use-cases but small enough to prevent /// memory eating by a malicious user. pub max_message_size: Option<usize>, /// The maximum size of a single message frame. `None` means no size limit. The limit is for /// frame payload NOT including the frame header. The default value is 16 megabytes which should /// be reasonably big for all normal use-cases but small enough to prevent memory eating /// by a malicious user. pub max_frame_size: Option<usize>, } impl Default for WebSocketConfig { fn default() -> Self { WebSocketConfig { max_send_queue: None, max_message_size: Some(64 << 20), max_frame_size: Some(16 << 20), } } } /// WebSocket input-output stream. /// /// This is THE structure you want to create to be able to speak the WebSocket protocol. /// It may be created by calling `connect`, `accept` or `client` functions. #[derive(Debug)] pub struct WebSocket<Stream> { /// The underlying socket. socket: Stream, /// The context for managing a WebSocket. context: WebSocketContext, } impl<Stream> WebSocket<Stream> { /// Convert a raw socket into a WebSocket without performing a handshake. /// /// Call this function if you're using Tungstenite as a part of a web framework /// or together with an existing one. If you need an initial handshake, use /// `connect()` or `accept()` functions of the crate to construct a websocket. pub fn from_raw_socket(stream: Stream, role: Role, config: Option<WebSocketConfig>) -> Self { WebSocket { socket: stream, context: WebSocketContext::new(role, config), } } /// Convert a raw socket into a WebSocket without performing a handshake. /// /// Call this function if you're using Tungstenite as a part of a web framework /// or together with an existing one. If you need an initial handshake, use /// `connect()` or `accept()` functions of the crate to construct a websocket. pub fn from_partially_read( stream: Stream, part: Vec<u8>, role: Role, config: Option<WebSocketConfig>, ) -> Self { WebSocket { socket: stream, context: WebSocketContext::from_partially_read(part, role, config), } } /// Returns a shared reference to the inner stream. pub fn get_ref(&self) -> &Stream { &self.socket } /// Returns a mutable reference to the inner stream. pub fn get_mut(&mut self) -> &mut Stream { &mut self.socket } /// Change the configuration. pub fn set_config(&mut self, set_func: impl FnOnce(&mut WebSocketConfig)) { self.context.set_config(set_func) } /// Check if it is possible to read messages. /// /// Reading is impossible after receiving `Message::Close`. It is still possible after /// sending close frame since the peer still may send some data before confirming close. pub fn can_read(&self) -> bool { self.context.can_read() } /// Check if it is possible to write messages. /// /// Writing gets impossible immediately after sending or receiving `Message::Close`. pub fn can_write(&self) -> bool { self.context.can_write() } } impl<Stream: Read + Write> WebSocket<Stream> { /// Read a message from stream, if possible. /// /// This will queue responses to ping and close messages to be sent. It will call /// `write_pending` before trying to read in order to make sure that those responses /// make progress even if you never call `write_pending`. That does mean that they /// get sent out earliest on the next call to `read_message`, `write_message` or `write_pending`. /// /// ## Closing the connection /// When the remote endpoint decides to close the connection this will return /// the close message with an optional close frame. /// /// You should continue calling `read_message`, `write_message` or `write_pending` to drive /// the reply to the close frame until [Error::ConnectionClosed] is returned. Once that happens /// it is safe to drop the underlying connection. pub fn read_message(&mut self) -> Result<Message> { self.context.read_message(&mut self.socket) } /// Send a message to stream, if possible. /// /// WebSocket will buffer a configurable number of messages at a time, except to reply to Ping /// requests. A Pong reply will jump the queue because the /// [websocket RFC](https://tools.ietf.org/html/rfc6455#section-5.5.2) specifies it should be sent /// as soon as is practical. /// /// Note that upon receiving a ping message, tungstenite cues a pong reply automatically. /// When you call either `read_message`, `write_message` or `write_pending` next it will try to send /// that pong out if the underlying connection can take more data. This means you should not /// respond to ping frames manually. /// /// You can however send pong frames manually in order to indicate a unidirectional heartbeat /// as described in [RFC 6455](https://tools.ietf.org/html/rfc6455#section-5.5.3). Note that /// if `read_message` returns a ping, you should call `write_pending` until it doesn't return /// WouldBlock before passing a pong to `write_message`, otherwise the response to the /// ping will not be sent, but rather replaced by your custom pong message. /// /// ## Errors /// - If the WebSocket's send queue is full, `SendQueueFull` will be returned /// along with the passed message. Otherwise, the message is queued and Ok(()) is returned. /// - If the connection is closed and should be dropped, this will return [Error::ConnectionClosed]. /// - If you try again after [Error::ConnectionClosed] was returned either from here or from `read_message`, /// [Error::AlreadyClosed] will be returned. This indicates a program error on your part. /// - [Error::Io] is returned if the underlying connection returns an error /// (consider these fatal except for WouldBlock). /// - [Error::Capacity] if your message size is bigger than the configured max message size. pub fn write_message(&mut self, message: Message) -> Result<()> { self.context.write_message(&mut self.socket, message) } /// Flush the pending send queue. pub fn write_pending(&mut self) -> Result<()> { self.context.write_pending(&mut self.socket) } /// Close the connection. /// /// This function guarantees that the close frame will be queued. /// There is no need to call it again. Calling this function is /// the same as calling `write_message(Message::Close(..))`. /// /// After queing the close frame you should continue calling `read_message` or /// `write_pending` to drive the close handshake to completion. /// /// The websocket RFC defines that the underlying connection should be closed /// by the server. Tungstenite takes care of this asymmetry for you. /// /// When the close handshake is finished (we have both sent and received /// a close message), `read_message` or `write_pending` will return /// [Error::ConnectionClosed] if this endpoint is the server. /// /// If this endpoint is a client, [Error::ConnectionClosed] will only be /// returned after the server has closed the underlying connection. /// /// It is thus safe to drop the underlying connection as soon as [Error::ConnectionClosed] /// is returned from `read_message` or `write_pending`. pub fn close(&mut self, code: Option<CloseFrame>) -> Result<()> { self.context.close(&mut self.socket, code) } } /// A context for managing WebSocket stream. #[derive(Debug)] pub struct WebSocketContext { /// Server or client? role: Role, /// encoder/decoder of frame. frame: FrameCodec, /// The state of processing, either "active" or "closing". state: WebSocketState, /// Receive: an incomplete message being processed. incomplete: Option<IncompleteMessage>, /// Send: a data send queue. send_queue: VecDeque<Frame>, /// Send: an OOB pong message. pong: Option<Frame>, /// The configuration for the websocket session. config: WebSocketConfig, } impl WebSocketContext { /// Create a WebSocket context that manages a post-handshake stream. pub fn new(role: Role, config: Option<WebSocketConfig>) -> Self { WebSocketContext { role, frame: FrameCodec::new(), state: WebSocketState::Active, incomplete: None, send_queue: VecDeque::new(), pong: None, config: config.unwrap_or_else(WebSocketConfig::default), } } /// Create a WebSocket context that manages an post-handshake stream. pub fn from_partially_read(part: Vec<u8>, role: Role, config: Option<WebSocketConfig>) -> Self { WebSocketContext { frame: FrameCodec::from_partially_read(part), ..WebSocketContext::new(role, config) } } /// Change the configuration. pub fn set_config(&mut self, set_func: impl FnOnce(&mut WebSocketConfig)) { set_func(&mut self.config) } /// Check if it is possible to read messages. /// /// Reading is impossible after receiving `Message::Close`. It is still possible after /// sending close frame since the peer still may send some data before confirming close. pub fn can_read(&self) -> bool { self.state.can_read() } /// Check if it is possible to write messages. /// /// Writing gets impossible immediately after sending or receiving `Message::Close`. pub fn can_write(&self) -> bool { self.state.is_active() } /// Read a message from the provided stream, if possible. /// /// This function sends pong and close responses automatically. /// However, it never blocks on write. pub fn read_message<Stream>(&mut self, stream: &mut Stream) -> Result<Message> where Stream: Read + Write, { // Do not read from already closed connections. self.state.check_active()?; loop { // Since we may get ping or close, we need to reply to the messages even during read. // Thus we call write_pending() but ignore its blocking. self.write_pending(stream).no_block()?; // If we get here, either write blocks or we have nothing to write. // Thus if read blocks, just let it return WouldBlock. if let Some(message) = self.read_message_frame(stream)? { trace!("Received message {}", message); return Ok(message); } } } /// Send a message to the provided stream, if possible. /// /// WebSocket will buffer a configurable number of messages at a time, except to reply to Ping /// and Close requests. If the WebSocket's send queue is full, `SendQueueFull` will be returned /// along with the passed message. Otherwise, the message is queued and Ok(()) is returned. /// /// Note that only the last pong frame is stored to be sent, and only the /// most recent pong frame is sent if multiple pong frames are queued. pub fn write_message<Stream>(&mut self, stream: &mut Stream, message: Message) -> Result<()> where Stream: Read + Write, { // When terminated, return AlreadyClosed. self.state.check_active()?; // Do not write after sending a close frame. if !self.state.is_active() { return Err(Error::Protocol( "Sending after closing is not allowed".into(), )); } if let Some(max_send_queue) = self.config.max_send_queue { if self.send_queue.len() >= max_send_queue { // Try to make some room for the new message. // Do not return here if write would block, ignore WouldBlock silently // since we must queue the message anyway. self.write_pending(stream).no_block()?; } if self.send_queue.len() >= max_send_queue { return Err(Error::SendQueueFull(message)); } } let frame = match message { Message::Text(data) => Frame::message(data.into(), OpCode::Data(OpData::Text), true), Message::Binary(data) => Frame::message(data, OpCode::Data(OpData::Binary), true), Message::Ping(data) => Frame::ping(data), Message::Pong(data) => { self.pong = Some(Frame::pong(data)); return self.write_pending(stream); } Message::Close(code) => return self.close(stream, code), }; self.send_queue.push_back(frame); self.write_pending(stream) } /// Flush the pending send queue. pub fn write_pending<Stream>(&mut self, stream: &mut Stream) -> Result<()> where Stream: Read + Write, { // First, make sure we have no pending frame sending. self.frame.write_pending(stream)?; // Upon receipt of a Ping frame, an endpoint MUST send a Pong frame in // response, unless it already received a Close frame. It SHOULD // respond with Pong frame as soon as is practical. (RFC 6455) if let Some(pong) = self.pong.take() { trace!("Sending pong reply"); self.send_one_frame(stream, pong)?; } // If we have any unsent frames, send them. trace!("Frames still in queue: {}", self.send_queue.len()); while let Some(data) = self.send_queue.pop_front() { self.send_one_frame(stream, data)?; } // If we get to this point, the send queue is empty and the underlying socket is still // willing to take more data. // If we're closing and there is nothing to send anymore, we should close the connection. if self.role == Role::Server && !self.state.can_read() { // The underlying TCP connection, in most normal cases, SHOULD be closed // first by the server, so that it holds the TIME_WAIT state and not the // client (as this would prevent it from re-opening the connection for 2 // maximum segment lifetimes (2MSL), while there is no corresponding // server impact as a TIME_WAIT connection is immediately reopened upon // a new SYN with a higher seq number). (RFC 6455) self.state = WebSocketState::Terminated; Err(Error::ConnectionClosed) } else { Ok(()) } } /// Close the connection. /// /// This function guarantees that the close frame will be queued. /// There is no need to call it again. Calling this function is /// the same as calling `write(Message::Close(..))`. pub fn close<Stream>(&mut self, stream: &mut Stream, code: Option<CloseFrame>) -> Result<()> where Stream: Read + Write, { if let WebSocketState::Active = self.state { self.state = WebSocketState::ClosedByUs; let frame = Frame::close(code); self.send_queue.push_back(frame); } else { // Already closed, nothing to do. } self.write_pending(stream) } } impl WebSocketContext { /// Try to decode one message frame. May return None. fn read_message_frame<Stream>(&mut self, stream: &mut Stream) -> Result<Option<Message>> where Stream: Read + Write, { if let Some(mut frame) = self .frame .read_frame(stream, self.config.max_frame_size) .check_connection_reset(self.state)? { if !self.state.can_read() { return Err(Error::Protocol( "Remote sent frame after having sent a Close Frame".into(), )); } // MUST be 0 unless an extension is negotiated that defines meanings // for non-zero values. If a nonzero value is received and none of // the negotiated extensions defines the meaning of such a nonzero // value, the receiving endpoint MUST _Fail the WebSocket // Connection_. { let hdr = frame.header(); if hdr.rsv1 || hdr.rsv2 || hdr.rsv3 { return Err(Error::Protocol("Reserved bits are non-zero".into())); } } match self.role { Role::Server => { if frame.is_masked() { // A server MUST remove masking for data frames received from a client // as described in Section 5.3. (RFC 6455) frame.apply_mask() } else { // The server MUST close the connection upon receiving a // frame that is not masked. (RFC 6455) return Err(Error::Protocol( "Received an unmasked frame from client".into(), )); } } Role::Client => { if frame.is_masked() { // A client MUST close a connection if it detects a masked frame. (RFC 6455) return Err(Error::Protocol( "Received a masked frame from server".into(), )); } } } match frame.header().opcode { OpCode::Control(ctl) => { match ctl { // All control frames MUST have a payload length of 125 bytes or less // and MUST NOT be fragmented. (RFC 6455) _ if !frame.header().is_final => { Err(Error::Protocol("Fragmented control frame".into())) } _ if frame.payload().len() > 125 => { Err(Error::Protocol("Control frame too big".into())) } OpCtl::Close => Ok(self.do_close(frame.into_close()?).map(Message::Close)), OpCtl::Reserved(i) => Err(Error::Protocol( format!("Unknown control frame type {}", i).into(), )), OpCtl::Ping => { let data = frame.into_data(); // No ping processing after we sent a close frame. if self.state.is_active() { self.pong = Some(Frame::pong(data.clone())); } Ok(Some(Message::Ping(data))) } OpCtl::Pong => Ok(Some(Message::Pong(frame.into_data()))), } } OpCode::Data(data) => { let fin = frame.header().is_final; match data { OpData::Continue => { if let Some(ref mut msg) = self.incomplete { msg.extend(frame.into_data(), self.config.max_message_size)?; } else { return Err(Error::Protocol( "Continue frame but nothing to continue".into(), )); } if fin { Ok(Some(self.incomplete.take().unwrap().complete()?)) } else { Ok(None) } } c if self.incomplete.is_some() => Err(Error::Protocol( format!("Received {} while waiting for more fragments", c).into(), )), OpData::Text | OpData::Binary => { let msg = { let message_type = match data { OpData::Text => IncompleteMessageType::Text, OpData::Binary => IncompleteMessageType::Binary, _ => panic!("Bug: message is not text nor binary"), }; let mut m = IncompleteMessage::new(message_type); m.extend(frame.into_data(), self.config.max_message_size)?; m }; if fin { Ok(Some(msg.complete()?)) } else { self.incomplete = Some(msg); Ok(None) } } OpData::Reserved(i) => Err(Error::Protocol( format!("Unknown data frame type {}", i).into(), )), } } } // match opcode } else { // Connection closed by peer match replace(&mut self.state, WebSocketState::Terminated) { WebSocketState::ClosedByPeer | WebSocketState::CloseAcknowledged => { Err(Error::ConnectionClosed) } _ => Err(Error::Protocol( "Connection reset without closing handshake".into(), )), } } } /// Received a close frame. Tells if we need to return a close frame to the user. #[allow(clippy::option_option)] fn do_close<'t>(&mut self, close: Option<CloseFrame<'t>>) -> Option<Option<CloseFrame<'t>>> { debug!("Received close frame: {:?}", close); match self.state { WebSocketState::Active => { let close_code = close.as_ref().map(|f| f.code); self.state = WebSocketState::ClosedByPeer; let reply = if let Some(code) = close_code { if code.is_allowed() { Frame::close(Some(CloseFrame { code: CloseCode::Normal, reason: "".into(), })) } else { Frame::close(Some(CloseFrame { code: CloseCode::Protocol, reason: "Protocol violation".into(), })) } } else { Frame::close(None) }; debug!("Replying to close with {:?}", reply); self.send_queue.push_back(reply); Some(close) } WebSocketState::ClosedByPeer | WebSocketState::CloseAcknowledged => { // It is already closed, just ignore. None } WebSocketState::ClosedByUs => { // We received a reply. self.state = WebSocketState::CloseAcknowledged; Some(close) } WebSocketState::Terminated => unreachable!(), } } /// Send a single pending frame. fn send_one_frame<Stream>(&mut self, stream: &mut Stream, mut frame: Frame) -> Result<()> where Stream: Read + Write, { match self.role { Role::Server => {} Role::Client => { // 5. If the data is being sent by the client, the frame(s) MUST be // masked as defined in Section 5.3. (RFC 6455) frame.set_random_mask(); } } trace!("Sending frame: {:?}", frame); self.frame .write_frame(stream, frame) .check_connection_reset(self.state) } } /// The current connection state. #[derive(Debug, PartialEq, Eq, Clone, Copy)] enum WebSocketState { /// The connection is active. Active, /// We initiated a close handshake. ClosedByUs, /// The peer initiated a close handshake. ClosedByPeer, /// The peer replied to our close handshake. CloseAcknowledged, /// The connection does not exist anymore. Terminated, } impl WebSocketState { /// Tell if we're allowed to process normal messages. fn is_active(self) -> bool { match self { WebSocketState::Active => true, _ => false, } } /// Tell if we should process incoming data. Note that if we send a close frame /// but the remote hasn't confirmed, they might have sent data before they receive our /// close frame, so we should still pass those to client code, hence ClosedByUs is valid. fn can_read(self) -> bool { match self { WebSocketState::Active | WebSocketState::ClosedByUs => true, _ => false, } } /// Check if the state is active, return error if not. fn check_active(self) -> Result<()> { match self { WebSocketState::Terminated => Err(Error::AlreadyClosed), _ => Ok(()), } } } /// Translate "Connection reset by peer" into `ConnectionClosed` if appropriate. trait CheckConnectionReset { fn check_connection_reset(self, state: WebSocketState) -> Self; } impl<T> CheckConnectionReset for Result<T> { fn check_connection_reset(self, state: WebSocketState) -> Self { match self { Err(Error::Io(io_error)) => Err({ if !state.can_read() && io_error.kind() == IoErrorKind::ConnectionReset { Error::ConnectionClosed } else { Error::Io(io_error) } }), x => x, } } } #[cfg(test)] mod tests { use super::{Message, Role, WebSocket, WebSocketConfig}; use std::io; use std::io::Cursor; struct WriteMoc<Stream>(Stream); impl<Stream> io::Write for WriteMoc<Stream> { fn write(&mut self, buf: &[u8]) -> io::Result<usize> { Ok(buf.len()) } fn flush(&mut self) -> io::Result<()> { Ok(()) } } impl<Stream: io::Read> io::Read for WriteMoc<Stream> { fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { self.0.read(buf) } } #[test] fn receive_messages() { let incoming = Cursor::new(vec![ 0x89, 0x02, 0x01, 0x02, 0x8a, 0x01, 0x03, 0x01, 0x07, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0x80, 0x06, 0x57, 0x6f, 0x72, 0x6c, 0x64, 0x21, 0x82, 0x03, 0x01, 0x02, 0x03, ]); let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, None); assert_eq!(socket.read_message().unwrap(), Message::Ping(vec![1, 2])); assert_eq!(socket.read_message().unwrap(), Message::Pong(vec![3])); assert_eq!( socket.read_message().unwrap(), Message::Text("Hello, World!".into()) ); assert_eq!( socket.read_message().unwrap(), Message::Binary(vec![0x01, 0x02, 0x03]) ); } #[test] fn size_limiting_text_fragmented() { let incoming = Cursor::new(vec![ 0x01, 0x07, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0x80, 0x06, 0x57, 0x6f, 0x72, 0x6c, 0x64, 0x21, ]); let limit = WebSocketConfig { max_message_size: Some(10), ..WebSocketConfig::default() }; let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, Some(limit)); assert_eq!( socket.read_message().unwrap_err().to_string(), "Space limit exceeded: Message too big: 7 + 6 > 10" ); } #[test] fn size_limiting_binary() { let incoming = Cursor::new(vec![0x82, 0x03, 0x01, 0x02, 0x03]); let limit = WebSocketConfig { max_message_size: Some(2), ..WebSocketConfig::default() }; let mut socket = WebSocket::from_raw_socket(WriteMoc(incoming), Role::Client, Some(limit)); assert_eq!( socket.read_message().unwrap_err().to_string(), "Space limit exceeded: Message too big: 0 + 3 > 2" ); } }