1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411
//! Provides an in-memory socket abstraction. //! //! The `memory-socket` crate provides the [`MemoryListener`] and [`MemorySocket`] types which can //! be thought of as in-memory versions of the standard library `TcpListener` and `TcpStream` //! types. //! //! ## Feature flags //! //! - `async`: Adds async support for [`MemorySocket`] and [`MemoryListener`] //! //! [`MemoryListener`]: struct.MemoryListener.html //! [`MemorySocket`]: struct.MemorySocket.html use bytes::{buf::BufExt, Buf, Bytes, BytesMut}; use flume::{Receiver, Sender}; use once_cell::sync::Lazy; use std::{ collections::HashMap, io::{ErrorKind, Read, Result, Write}, num::NonZeroU16, sync::Mutex, }; #[cfg(feature = "async")] mod r#async; #[cfg(feature = "async")] pub use r#async::IncomingStream; static SWITCHBOARD: Lazy<Mutex<SwitchBoard>> = Lazy::new(|| Mutex::new(SwitchBoard(HashMap::default(), 1))); struct SwitchBoard(HashMap<NonZeroU16, Sender<MemorySocket>>, u16); /// An in-memory socket server, listening for connections. /// /// After creating a `MemoryListener` by [`bind`]ing it to a socket address, it listens /// for incoming connections. These can be accepted by calling [`accept`] or by iterating over /// iterating over the [`Incoming`] iterator returned by [`incoming`][`MemoryListener::incoming`]. /// /// The socket will be closed when the value is dropped. /// /// [`accept`]: #method.accept /// [`bind`]: #method.bind /// [`Incoming`]: struct.Incoming.html /// [`MemoryListener::incoming`]: #method.incoming /// /// # Examples /// /// ```no_run /// use std::io::{Read, Result, Write}; /// /// use memory_socket::{MemoryListener, MemorySocket}; /// /// fn write_stormlight(mut stream: MemorySocket) -> Result<()> { /// let msg = b"The most important step a person can take is always the next one."; /// stream.write_all(msg)?; /// stream.flush() /// } /// /// fn main() -> Result<()> { /// let mut listener = MemoryListener::bind(16)?; /// /// // accept connections and process them serially /// for stream in listener.incoming() { /// write_stormlight(stream?)?; /// } /// Ok(()) /// } /// ``` pub struct MemoryListener { incoming: Receiver<MemorySocket>, port: NonZeroU16, } impl Drop for MemoryListener { fn drop(&mut self) { let mut switchboard = (&*SWITCHBOARD).lock().unwrap(); // Remove the Sending side of the channel in the switchboard when // MemoryListener is dropped switchboard.0.remove(&self.port); } } impl MemoryListener { /// Creates a new `MemoryListener` which will be bound to the specified /// port. /// /// The returned listener is ready for accepting connections. /// /// Binding with a port number of `0` will request that a port be assigned /// to this listener. The port allocated can be queried via the /// [`local_addr`] method. /// /// [`local_addr`]: #method.local_addr /// /// # Examples /// /// Create a MemoryListener bound to port 16: /// /// ```no_run /// use memory_socket::MemoryListener; /// /// # fn main () -> ::std::io::Result<()> { /// let listener = MemoryListener::bind(16)?; /// # Ok(())} /// ``` pub fn bind(port: u16) -> Result<Self> { let mut switchboard = (&*SWITCHBOARD).lock().unwrap(); // Get the port we should bind to. If 0 was given, use a random port let port = if let Some(port) = NonZeroU16::new(port) { if switchboard.0.contains_key(&port) { return Err(ErrorKind::AddrInUse.into()); } port } else { loop { let port = NonZeroU16::new(switchboard.1).unwrap_or_else(|| unreachable!()); // The switchboard is full and all ports are in use if switchboard.0.len() == (std::u16::MAX - 1) as usize { return Err(ErrorKind::AddrInUse.into()); } // Instead of overflowing to 0, resume searching at port 1 since port 0 isn't a // valid port to bind to. if switchboard.1 == std::u16::MAX { switchboard.1 = 1; } else { switchboard.1 += 1; } if !switchboard.0.contains_key(&port) { break port; } } }; let (sender, receiver) = flume::unbounded(); switchboard.0.insert(port, sender); Ok(Self { incoming: receiver, port, }) } /// Returns the local address that this listener is bound to. /// /// This can be useful, for example, when binding to port `0` to figure out /// which port was actually bound. /// /// # Examples /// /// ``` /// use memory_socket::MemoryListener; /// /// # fn main () -> ::std::io::Result<()> { /// let listener = MemoryListener::bind(16)?; /// /// assert_eq!(listener.local_addr(), 16); /// # Ok(())} /// ``` pub fn local_addr(&self) -> u16 { self.port.get() } /// Returns an iterator over the connections being received on this /// listener. /// /// The returned iterator will never return `None`. Iterating over /// it is equivalent to calling [`accept`] in a loop. /// /// [`accept`]: #method.accept /// /// # Examples /// /// ```no_run /// use memory_socket::MemoryListener; /// use std::io::{Read, Write}; /// /// let mut listener = MemoryListener::bind(80).unwrap(); /// /// for stream in listener.incoming() { /// match stream { /// Ok(stream) => { /// println!("new client!"); /// } /// Err(e) => { /* connection failed */ } /// } /// } /// ``` pub fn incoming(&self) -> Incoming<'_> { Incoming { inner: self } } /// Accept a new incoming connection from this listener. /// /// This function will block the calling thread until a new connection /// is established. When established, the corresponding [`MemorySocket`] /// will be returned. /// /// [`MemorySocket`]: struct.MemorySocket.html /// /// # Examples /// /// ```no_run /// use std::net::TcpListener; /// use memory_socket::MemoryListener; /// /// let mut listener = MemoryListener::bind(8080).unwrap(); /// match listener.accept() { /// Ok(_socket) => println!("new client!"), /// Err(e) => println!("couldn't get client: {:?}", e), /// } /// ``` pub fn accept(&self) -> Result<MemorySocket> { self.incoming.iter().next().ok_or_else(|| unreachable!()) } } /// An iterator that infinitely [`accept`]s connections on a [`MemoryListener`]. /// /// This `struct` is created by the [`incoming`] method on [`MemoryListener`]. /// See its documentation for more info. /// /// [`accept`]: struct.MemoryListener.html#method.accept /// [`incoming`]: struct.MemoryListener.html#method.incoming /// [`MemoryListener`]: struct.MemoryListener.html pub struct Incoming<'a> { inner: &'a MemoryListener, } impl<'a> Iterator for Incoming<'a> { type Item = Result<MemorySocket>; fn next(&mut self) -> Option<Self::Item> { Some(self.inner.accept()) } } /// An in-memory stream between two local sockets. /// /// A `MemorySocket` can either be created by connecting to an endpoint, via the /// [`connect`] method, or by [accepting] a connection from a [listener]. /// It can be read or written to using the `Read` and `Write` traits. /// /// # Examples /// /// ``` /// use std::io::{Read, Result, Write}; /// use memory_socket::MemorySocket; /// /// # fn main() -> Result<()> { /// let (mut socket_a, mut socket_b) = MemorySocket::new_pair(); /// /// socket_a.write_all(b"stormlight")?; /// socket_a.flush()?; /// /// let mut buf = [0; 10]; /// socket_b.read_exact(&mut buf)?; /// assert_eq!(&buf, b"stormlight"); /// /// # Ok(())} /// ``` /// /// [`connect`]: struct.MemorySocket.html#method.connect /// [accepting]: struct.MemoryListener.html#method.accept /// [listener]: struct.MemoryListener.html pub struct MemorySocket { incoming: Receiver<Bytes>, outgoing: Sender<Bytes>, write_buffer: BytesMut, current_buffer: Option<Bytes>, seen_eof: bool, } impl MemorySocket { fn new(incoming: Receiver<Bytes>, outgoing: Sender<Bytes>) -> Self { Self { incoming, outgoing, write_buffer: BytesMut::new(), current_buffer: None, seen_eof: false, } } /// Construct both sides of an in-memory socket. /// /// # Examples /// /// ``` /// use memory_socket::MemorySocket; /// /// let (socket_a, socket_b) = MemorySocket::new_pair(); /// ``` pub fn new_pair() -> (Self, Self) { let (a_tx, a_rx) = flume::unbounded(); let (b_tx, b_rx) = flume::unbounded(); let a = Self::new(a_rx, b_tx); let b = Self::new(b_rx, a_tx); (a, b) } /// Create a new in-memory Socket connected to the specified port. /// /// This function will create a new MemorySocket socket and attempt to connect it to /// the `port` provided. /// /// # Examples /// /// ``` /// use memory_socket::MemorySocket; /// /// # fn main () -> ::std::io::Result<()> { /// # let _listener = memory_socket::MemoryListener::bind(16)?; /// let socket = MemorySocket::connect(16)?; /// # Ok(())} /// ``` pub fn connect(port: u16) -> Result<MemorySocket> { let mut switchboard = (&*SWITCHBOARD).lock().unwrap(); // Find port to connect to let port = NonZeroU16::new(port).ok_or_else(|| ErrorKind::AddrNotAvailable)?; let sender = switchboard .0 .get_mut(&port) .ok_or_else(|| ErrorKind::AddrNotAvailable)?; let (socket_a, socket_b) = Self::new_pair(); // Send the socket to the listener sender .send(socket_a) .map_err(|_| ErrorKind::AddrNotAvailable)?; Ok(socket_b) } } impl Read for MemorySocket { fn read(&mut self, buf: &mut [u8]) -> Result<usize> { let mut bytes_read = 0; loop { // If we've already filled up the buffer then we can return if bytes_read == buf.len() { return Ok(bytes_read); } match self.current_buffer { // We still have data to copy to `buf` Some(ref mut current_buffer) if current_buffer.has_remaining() => { let bytes_to_read = ::std::cmp::min(buf.len() - bytes_read, current_buffer.remaining()); debug_assert!(bytes_to_read > 0); current_buffer .take(bytes_to_read) .copy_to_slice(&mut buf[bytes_read..(bytes_read + bytes_to_read)]); bytes_read += bytes_to_read; } // Either we've exhausted our current buffer or we don't have one _ => { // If we've read anything up to this point return the bytes read if bytes_read > 0 { return Ok(bytes_read); } self.current_buffer = match self.incoming.recv() { Ok(buf) => Some(buf), // The remote side hung up, if this is the first time we've seen EOF then // we should return `Ok(0)` otherwise an UnexpectedEof Error Err(_) => { if self.seen_eof { return Err(ErrorKind::UnexpectedEof.into()); } else { self.seen_eof = true; return Ok(0); } } } } } } } } impl Write for MemorySocket { fn write(&mut self, buf: &[u8]) -> Result<usize> { self.write_buffer.extend_from_slice(buf); Ok(buf.len()) } fn flush(&mut self) -> Result<()> { if !self.write_buffer.is_empty() { self.outgoing .send(self.write_buffer.split().freeze()) .map_err(|_| ErrorKind::BrokenPipe.into()) } else { Ok(()) } } }