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use crate::future::poll_fn; use crate::io::{AsyncRead, AsyncWrite, PollEvented, ReadBuf}; use crate::net::tcp::split::{split, ReadHalf, WriteHalf}; use crate::net::tcp::split_owned::{split_owned, OwnedReadHalf, OwnedWriteHalf}; use crate::net::{to_socket_addrs, ToSocketAddrs}; use std::convert::TryFrom; use std::fmt; use std::io::{self, Read, Write}; use std::net::{Shutdown, SocketAddr}; use std::pin::Pin; use std::task::{Context, Poll}; cfg_net! { /// A TCP stream between a local and a remote socket. /// /// A TCP stream can either be created by connecting to an endpoint, via the /// [`connect`] method, or by [accepting] a connection from a [listener]. /// /// Reading and writing to a `TcpStream` is usually done using the /// convenience methods found on the [`AsyncReadExt`] and [`AsyncWriteExt`] /// traits. Examples import these traits through [the prelude]. /// /// [`connect`]: method@TcpStream::connect /// [accepting]: method@crate::net::TcpListener::accept /// [listener]: struct@crate::net::TcpListener /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt /// [the prelude]: crate::prelude /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// use tokio::prelude::*; /// use std::error::Error; /// /// #[tokio::main] /// async fn main() -> Result<(), Box<dyn Error>> { /// // Connect to a peer /// let mut stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// // Write some data. /// stream.write_all(b"hello world!").await?; /// /// Ok(()) /// } /// ``` /// /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait. /// /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt pub struct TcpStream { io: PollEvented<mio::net::TcpStream>, } } impl TcpStream { /// Opens a TCP connection to a remote host. /// /// `addr` is an address of the remote host. Anything which implements the /// [`ToSocketAddrs`] trait can be supplied as the address. Note that /// strings only implement this trait when the **`net`** feature is enabled, /// as strings may contain domain names that need to be resolved. /// /// If `addr` yields multiple addresses, connect will be attempted with each /// of the addresses until a connection is successful. If none of the /// addresses result in a successful connection, the error returned from the /// last connection attempt (the last address) is returned. /// /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// use tokio::prelude::*; /// use std::error::Error; /// /// #[tokio::main] /// async fn main() -> Result<(), Box<dyn Error>> { /// // Connect to a peer /// let mut stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// // Write some data. /// stream.write_all(b"hello world!").await?; /// /// Ok(()) /// } /// ``` /// /// The [`write_all`] method is defined on the [`AsyncWriteExt`] trait. /// /// [`write_all`]: fn@crate::io::AsyncWriteExt::write_all /// [`AsyncWriteExt`]: trait@crate::io::AsyncWriteExt pub async fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<TcpStream> { let addrs = to_socket_addrs(addr).await?; let mut last_err = None; for addr in addrs { match TcpStream::connect_addr(addr).await { Ok(stream) => return Ok(stream), Err(e) => last_err = Some(e), } } Err(last_err.unwrap_or_else(|| { io::Error::new( io::ErrorKind::InvalidInput, "could not resolve to any address", ) })) } /// Establishes a connection to the specified `addr`. async fn connect_addr(addr: SocketAddr) -> io::Result<TcpStream> { let sys = mio::net::TcpStream::connect(addr)?; TcpStream::connect_mio(sys).await } pub(crate) async fn connect_mio(sys: mio::net::TcpStream) -> io::Result<TcpStream> { let stream = TcpStream::new(sys)?; // Once we've connected, wait for the stream to be writable as // that's when the actual connection has been initiated. Once we're // writable we check for `take_socket_error` to see if the connect // actually hit an error or not. // // If all that succeeded then we ship everything on up. poll_fn(|cx| stream.io.poll_write_ready(cx)).await?; if let Some(e) = stream.io.get_ref().take_error()? { return Err(e); } Ok(stream) } pub(crate) fn new(connected: mio::net::TcpStream) -> io::Result<TcpStream> { let io = PollEvented::new(connected)?; Ok(TcpStream { io }) } /// Creates new `TcpStream` from a `std::net::TcpStream`. /// /// This function will convert a TCP stream created by the standard library /// to a TCP stream ready to be used with the provided event loop handle. /// /// # Examples /// /// ```rust,no_run /// use std::error::Error; /// use tokio::net::TcpStream; /// /// #[tokio::main] /// async fn main() -> Result<(), Box<dyn Error>> { /// let std_stream = std::net::TcpStream::connect("127.0.0.1:34254")?; /// let stream = TcpStream::from_std(std_stream)?; /// Ok(()) /// } /// ``` /// /// # Panics /// /// This function panics if thread-local runtime is not set. /// /// The runtime is usually set implicitly when this function is called /// from a future driven by a tokio runtime, otherwise runtime can be set /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function. pub fn from_std(stream: std::net::TcpStream) -> io::Result<TcpStream> { let io = mio::net::TcpStream::from_std(stream); let io = PollEvented::new(io)?; Ok(TcpStream { io }) } /// Returns the local address that this stream is bound to. /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> { /// let stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// println!("{:?}", stream.local_addr()?); /// # Ok(()) /// # } /// ``` pub fn local_addr(&self) -> io::Result<SocketAddr> { self.io.get_ref().local_addr() } /// Returns the remote address that this stream is connected to. /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> { /// let stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// println!("{:?}", stream.peer_addr()?); /// # Ok(()) /// # } /// ``` pub fn peer_addr(&self) -> io::Result<SocketAddr> { self.io.get_ref().peer_addr() } /// Attempts to receive data on the socket, without removing that data from /// the queue, registering the current task for wakeup if data is not yet /// available. /// /// # Return value /// /// The function returns: /// /// * `Poll::Pending` if data is not yet available. /// * `Poll::Ready(Ok(n))` if data is available. `n` is the number of bytes peeked. /// * `Poll::Ready(Err(e))` if an error is encountered. /// /// # Errors /// /// This function may encounter any standard I/O error except `WouldBlock`. /// /// # Examples /// /// ```no_run /// use tokio::io; /// use tokio::net::TcpStream; /// /// use futures::future::poll_fn; /// /// #[tokio::main] /// async fn main() -> io::Result<()> { /// let stream = TcpStream::connect("127.0.0.1:8000").await?; /// let mut buf = [0; 10]; /// /// poll_fn(|cx| { /// stream.poll_peek(cx, &mut buf) /// }).await?; /// /// Ok(()) /// } /// ``` pub fn poll_peek(&self, cx: &mut Context<'_>, buf: &mut [u8]) -> Poll<io::Result<usize>> { loop { let ev = ready!(self.io.poll_read_ready(cx))?; match self.io.get_ref().peek(buf) { Ok(ret) => return Poll::Ready(Ok(ret)), Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => { self.io.clear_readiness(ev); } Err(e) => return Poll::Ready(Err(e)), } } } /// Receives data on the socket from the remote address to which it is /// connected, without removing that data from the queue. On success, /// returns the number of bytes peeked. /// /// Successive calls return the same data. This is accomplished by passing /// `MSG_PEEK` as a flag to the underlying recv system call. /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// use tokio::prelude::*; /// use std::error::Error; /// /// #[tokio::main] /// async fn main() -> Result<(), Box<dyn Error>> { /// // Connect to a peer /// let mut stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// let mut b1 = [0; 10]; /// let mut b2 = [0; 10]; /// /// // Peek at the data /// let n = stream.peek(&mut b1).await?; /// /// // Read the data /// assert_eq!(n, stream.read(&mut b2[..n]).await?); /// assert_eq!(&b1[..n], &b2[..n]); /// /// Ok(()) /// } /// ``` /// /// The [`read`] method is defined on the [`AsyncReadExt`] trait. /// /// [`read`]: fn@crate::io::AsyncReadExt::read /// [`AsyncReadExt`]: trait@crate::io::AsyncReadExt pub async fn peek(&self, buf: &mut [u8]) -> io::Result<usize> { self.io .async_io(mio::Interest::READABLE, |io| io.peek(buf)) .await } /// Shuts down the read, write, or both halves of this connection. /// /// This function will cause all pending and future I/O on the specified /// portions to return immediately with an appropriate value (see the /// documentation of `Shutdown`). /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// use std::error::Error; /// use std::net::Shutdown; /// /// #[tokio::main] /// async fn main() -> Result<(), Box<dyn Error>> { /// // Connect to a peer /// let stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// // Shutdown the stream /// stream.shutdown(Shutdown::Write)?; /// /// Ok(()) /// } /// ``` pub fn shutdown(&self, how: Shutdown) -> io::Result<()> { self.io.get_ref().shutdown(how) } /// Gets the value of the `TCP_NODELAY` option on this socket. /// /// For more information about this option, see [`set_nodelay`]. /// /// [`set_nodelay`]: TcpStream::set_nodelay /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> { /// let stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// println!("{:?}", stream.nodelay()?); /// # Ok(()) /// # } /// ``` pub fn nodelay(&self) -> io::Result<bool> { self.io.get_ref().nodelay() } /// Sets the value of the `TCP_NODELAY` option on this socket. /// /// If set, this option disables the Nagle algorithm. This means that /// segments are always sent as soon as possible, even if there is only a /// small amount of data. When not set, data is buffered until there is a /// sufficient amount to send out, thereby avoiding the frequent sending of /// small packets. /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> { /// let stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// stream.set_nodelay(true)?; /// # Ok(()) /// # } /// ``` pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> { self.io.get_ref().set_nodelay(nodelay) } /// Gets the value of the `IP_TTL` option for this socket. /// /// For more information about this option, see [`set_ttl`]. /// /// [`set_ttl`]: TcpStream::set_ttl /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> { /// let stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// println!("{:?}", stream.ttl()?); /// # Ok(()) /// # } /// ``` pub fn ttl(&self) -> io::Result<u32> { self.io.get_ref().ttl() } /// Sets the value for the `IP_TTL` option on this socket. /// /// This value sets the time-to-live field that is used in every packet sent /// from this socket. /// /// # Examples /// /// ```no_run /// use tokio::net::TcpStream; /// /// # async fn dox() -> Result<(), Box<dyn std::error::Error>> { /// let stream = TcpStream::connect("127.0.0.1:8080").await?; /// /// stream.set_ttl(123)?; /// # Ok(()) /// # } /// ``` pub fn set_ttl(&self, ttl: u32) -> io::Result<()> { self.io.get_ref().set_ttl(ttl) } // These lifetime markers also appear in the generated documentation, and make // it more clear that this is a *borrowed* split. #[allow(clippy::needless_lifetimes)] /// Splits a `TcpStream` into a read half and a write half, which can be used /// to read and write the stream concurrently. /// /// This method is more efficient than [`into_split`], but the halves cannot be /// moved into independently spawned tasks. /// /// [`into_split`]: TcpStream::into_split() pub fn split<'a>(&'a mut self) -> (ReadHalf<'a>, WriteHalf<'a>) { split(self) } /// Splits a `TcpStream` into a read half and a write half, which can be used /// to read and write the stream concurrently. /// /// Unlike [`split`], the owned halves can be moved to separate tasks, however /// this comes at the cost of a heap allocation. /// /// **Note:** Dropping the write half will shut down the write half of the TCP /// stream. This is equivalent to calling [`shutdown(Write)`] on the `TcpStream`. /// /// [`split`]: TcpStream::split() /// [`shutdown(Write)`]: fn@crate::net::TcpStream::shutdown pub fn into_split(self) -> (OwnedReadHalf, OwnedWriteHalf) { split_owned(self) } // == Poll IO functions that takes `&self` == // // They are not public because (taken from the doc of `PollEvented`): // // While `PollEvented` is `Sync` (if the underlying I/O type is `Sync`), the // caller must ensure that there are at most two tasks that use a // `PollEvented` instance concurrently. One for reading and one for writing. // While violating this requirement is "safe" from a Rust memory model point // of view, it will result in unexpected behavior in the form of lost // notifications and tasks hanging. pub(crate) fn poll_read_priv( &self, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>, ) -> Poll<io::Result<()>> { loop { let ev = ready!(self.io.poll_read_ready(cx))?; // Safety: `TcpStream::read` will not peek at the maybe uinitialized bytes. let b = unsafe { &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]) }; match self.io.get_ref().read(b) { Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => { self.io.clear_readiness(ev); } Ok(n) => { // Safety: We trust `TcpStream::read` to have filled up `n` bytes // in the buffer. unsafe { buf.assume_init(n); } buf.advance(n); return Poll::Ready(Ok(())); } Err(e) => return Poll::Ready(Err(e)), } } } pub(super) fn poll_write_priv( &self, cx: &mut Context<'_>, buf: &[u8], ) -> Poll<io::Result<usize>> { loop { let ev = ready!(self.io.poll_write_ready(cx))?; match self.io.get_ref().write(buf) { Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => { self.io.clear_readiness(ev); } x => return Poll::Ready(x), } } } } impl TryFrom<std::net::TcpStream> for TcpStream { type Error = io::Error; /// Consumes stream, returning the tokio I/O object. /// /// This is equivalent to /// [`TcpStream::from_std(stream)`](TcpStream::from_std). fn try_from(stream: std::net::TcpStream) -> Result<Self, Self::Error> { Self::from_std(stream) } } // ===== impl Read / Write ===== impl AsyncRead for TcpStream { fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>, ) -> Poll<io::Result<()>> { self.poll_read_priv(cx, buf) } } impl AsyncWrite for TcpStream { fn poll_write( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8], ) -> Poll<io::Result<usize>> { self.poll_write_priv(cx, buf) } #[inline] fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> { // tcp flush is a no-op Poll::Ready(Ok(())) } fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<()>> { self.shutdown(std::net::Shutdown::Write)?; Poll::Ready(Ok(())) } } impl fmt::Debug for TcpStream { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { self.io.get_ref().fmt(f) } } #[cfg(unix)] mod sys { use super::TcpStream; use std::os::unix::prelude::*; impl AsRawFd for TcpStream { fn as_raw_fd(&self) -> RawFd { self.io.get_ref().as_raw_fd() } } } #[cfg(windows)] mod sys { use super::TcpStream; use std::os::windows::prelude::*; impl AsRawSocket for TcpStream { fn as_raw_socket(&self) -> RawSocket { self.io.get_ref().as_raw_socket() } } }