socks5-impl 0.9.1

use crate::protocol::{Address, AsyncStreamOperation, Reply, Response};
use std::{
    marker::PhantomData,
    net::{SocketAddr, ToSocketAddrs},
    pin::Pin,
    task::{Context, Poll},
};
use tokio::{
    io::{AsyncRead, AsyncWrite, AsyncWriteExt, ReadBuf},
    net::{
        TcpListener, TcpStream,
        tcp::{ReadHalf, WriteHalf},
    },
};

/// Socks5 command type `Bind`
///
/// By [`wait_request`](crate::server::connection::Authenticated::wait_request)
/// on an [`Authenticated`](crate::server::connection::Authenticated) from SOCKS5 client,
/// you may get a `Bind<NeedFirstReply>`. After replying the client 2 times
/// using [`reply()`](crate::server::connection::Bind::reply),
/// you will get a `Bind<Ready>`, which can be used as a regular async TCP stream.
///
/// A `Bind<S>` can be converted to a regular tokio [`TcpStream`](https://docs.rs/tokio/latest/tokio/net/struct.TcpStream.html) by using the `From` trait.
#[derive(Debug)]
pub struct Bind<S> {
    stream: TcpStream,
    _state: PhantomData<S>,
}

/// Marker type indicating that the connection needs its first reply.
#[derive(Debug, Default)]
pub struct NeedFirstReply;

/// Marker type indicating that the connection needs its second reply.
#[derive(Debug, Default)]
pub struct NeedSecondReply;

/// Marker type indicating that the connection is ready to use as a regular TCP stream.
#[derive(Debug, Default)]
pub struct Ready;

impl Bind<NeedFirstReply> {
    #[inline]
    pub(super) fn new(stream: TcpStream) -> Self {
        Self {
            stream,
            _state: PhantomData,
        }
    }

    /// Reply to the SOCKS5 client with the given reply and address.
    ///
    /// If encountered an error while writing the reply, the error alongside the original `TcpStream` is returned.
    pub async fn reply(mut self, reply: Reply, addr: Address) -> std::io::Result<Bind<NeedSecondReply>> {
        let resp = Response::new(reply, addr);
        resp.write_to_async_stream(&mut self.stream).await?;
        Ok(Bind::<NeedSecondReply>::new(self.stream))
    }

    /// Accept an incoming connection for SOCKS5 BIND.
    ///
    /// This binds a TCP listener to the requested `bind_addr`, sends the first BIND
    /// reply with the actual bound address, then waits for the remote peer to connect.
    /// The returned `Bind<NeedSecondReply>` can be used to send the second reply.
    pub async fn accept(self, bind_addr: Address) -> std::io::Result<(Bind<NeedSecondReply>, TcpStream)> {
        let bind_addr = bind_addr
            .to_socket_addrs()?
            .next()
            .ok_or_else(|| std::io::Error::new(std::io::ErrorKind::InvalidInput, "invalid bind address"))?;

        let listener = match TcpListener::bind(bind_addr).await {
            Ok(listener) => listener,
            Err(err) => {
                let _ = self.reply(Reply::GeneralFailure, Address::unspecified()).await;
                return Err(err);
            }
        };

        let local_addr = listener.local_addr()?;
        let bind = self.reply(Reply::Succeeded, Address::from(local_addr)).await?;
        let (incoming, _) = listener.accept().await?;
        Ok((bind, incoming))
    }

    /// Fully complete BIND handling, including first reply, accept, and second reply.
    pub async fn bind(self, bind_addr: Address) -> std::io::Result<(Bind<Ready>, TcpStream)> {
        let (bind, incoming) = self.accept(bind_addr).await?;
        let remote_addr = incoming.peer_addr()?;
        let conn = match bind.reply(Reply::Succeeded, Address::from(remote_addr)).await {
            Ok(conn) => conn,
            Err((err, _stream)) => return Err(err),
        };
        Ok((conn, incoming))
    }

    /// Causes the other peer to receive a read of length 0, indicating that no more data will be sent. This only closes the stream in one direction.
    #[inline]
    pub async fn shutdown(&mut self) -> std::io::Result<()> {
        self.stream.shutdown().await
    }

    /// Returns the local address that this stream is bound to.
    #[inline]
    pub fn local_addr(&self) -> std::io::Result<SocketAddr> {
        self.stream.local_addr()
    }

    /// Returns the remote address that this stream is connected to.
    #[inline]
    pub fn peer_addr(&self) -> std::io::Result<SocketAddr> {
        self.stream.peer_addr()
    }

    /// Gets the value of the `TCP_NODELAY` option on this socket.
    ///
    /// For more information about this option, see [`set_nodelay`](crate::server::connection::Bind::set_nodelay).
    #[inline]
    pub fn nodelay(&self) -> std::io::Result<bool> {
        self.stream.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.
    pub fn set_nodelay(&self, nodelay: bool) -> std::io::Result<()> {
        self.stream.set_nodelay(nodelay)
    }

    /// Gets the value of the `IP_TTL` option for this socket.
    ///
    /// For more information about this option, see [`set_ttl`](crate::server::connection::Bind::set_ttl).
    pub fn ttl(&self) -> std::io::Result<u32> {
        self.stream.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.
    pub fn set_ttl(&self, ttl: u32) -> std::io::Result<()> {
        self.stream.set_ttl(ttl)
    }
}

impl Bind<NeedSecondReply> {
    #[inline]
    fn new(stream: TcpStream) -> Self {
        Self {
            stream,
            _state: PhantomData,
        }
    }

    /// Reply to the SOCKS5 client with the given reply and address.
    ///
    /// If encountered an error while writing the reply, the error alongside the original `TcpStream` is returned.
    pub async fn reply(mut self, reply: Reply, addr: Address) -> Result<Bind<Ready>, (std::io::Error, TcpStream)> {
        let resp = Response::new(reply, addr);

        if let Err(err) = resp.write_to_async_stream(&mut self.stream).await {
            return Err((err, self.stream));
        }

        Ok(Bind::<Ready>::new(self.stream))
    }

    /// Causes the other peer to receive a read of length 0, indicating that no more data will be sent. This only closes the stream in one direction.
    #[inline]
    pub async fn shutdown(&mut self) -> std::io::Result<()> {
        self.stream.shutdown().await
    }

    /// Returns the local address that this stream is bound to.
    #[inline]
    pub fn local_addr(&self) -> std::io::Result<SocketAddr> {
        self.stream.local_addr()
    }

    /// Returns the remote address that this stream is connected to.
    #[inline]
    pub fn peer_addr(&self) -> std::io::Result<SocketAddr> {
        self.stream.peer_addr()
    }

    /// Gets the value of the `TCP_NODELAY` option on this socket.
    ///
    /// For more information about this option, see
    /// [`set_nodelay`](crate::server::connection::Bind::set_nodelay).
    #[inline]
    pub fn nodelay(&self) -> std::io::Result<bool> {
        self.stream.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.
    pub fn set_nodelay(&self, nodelay: bool) -> std::io::Result<()> {
        self.stream.set_nodelay(nodelay)
    }

    /// Gets the value of the `IP_TTL` option for this socket.
    ///
    /// For more information about this option, see [`set_ttl`](crate::server::connection::Bind::set_ttl).
    pub fn ttl(&self) -> std::io::Result<u32> {
        self.stream.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.
    pub fn set_ttl(&self, ttl: u32) -> std::io::Result<()> {
        self.stream.set_ttl(ttl)
    }
}

impl Bind<Ready> {
    #[inline]
    fn new(stream: TcpStream) -> Self {
        Self {
            stream,
            _state: PhantomData,
        }
    }

    /// Split the connection into a read and a write half.
    #[inline]
    pub fn split(&mut self) -> (ReadHalf<'_>, WriteHalf<'_>) {
        self.stream.split()
    }
}

impl std::ops::Deref for Bind<Ready> {
    type Target = TcpStream;

    #[inline]
    fn deref(&self) -> &Self::Target {
        &self.stream
    }
}

impl std::ops::DerefMut for Bind<Ready> {
    #[inline]
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.stream
    }
}

impl AsyncRead for Bind<Ready> {
    #[inline]
    fn poll_read(mut self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>) -> Poll<std::io::Result<()>> {
        Pin::new(&mut self.stream).poll_read(cx, buf)
    }
}

impl AsyncWrite for Bind<Ready> {
    #[inline]
    fn poll_write(mut self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<std::io::Result<usize>> {
        Pin::new(&mut self.stream).poll_write(cx, buf)
    }

    #[inline]
    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
        Pin::new(&mut self.stream).poll_flush(cx)
    }

    #[inline]
    fn poll_shutdown(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
        Pin::new(&mut self.stream).poll_shutdown(cx)
    }
}

impl<S> From<Bind<S>> for TcpStream {
    #[inline]
    fn from(conn: Bind<S>) -> Self {
        conn.stream
    }
}