283 lines
10 KiB
Rust
283 lines
10 KiB
Rust
use std::{net::SocketAddr, time::Duration};
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use anyhow::Context;
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use buffers::{ByteBuf, ByteString};
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use clone_to_owned::CloneToOwned;
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use librqbit_core::{lengths::ChunkInfo, peer_id::try_decode_peer_id};
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use log::{debug, trace};
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use peer_binary_protocol::{
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extended::{handshake::ExtendedHandshake, ExtendedMessage},
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serialize_piece_preamble, Handshake, Message, MessageBorrowed, MessageDeserializeError,
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MessageOwned, PIECE_MESSAGE_DEFAULT_LEN,
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};
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use tokio::time::timeout;
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pub trait PeerConnectionHandler {
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fn get_have_bytes(&self) -> u64;
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fn serialize_bitfield_message_to_buf(&self, buf: &mut Vec<u8>) -> Option<usize>;
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fn on_handshake(&self, handshake: Handshake) -> anyhow::Result<()>;
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fn on_extended_handshake(
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&self,
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extended_handshake: &ExtendedHandshake<ByteBuf>,
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) -> anyhow::Result<()>;
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fn on_received_message(&self, msg: Message<ByteBuf<'_>>) -> anyhow::Result<()>;
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fn on_uploaded_bytes(&self, bytes: u32);
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fn read_chunk(&self, chunk: &ChunkInfo, buf: &mut [u8]) -> anyhow::Result<()>;
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}
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#[derive(Debug)]
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pub enum WriterRequest {
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Message(MessageOwned),
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ReadChunkRequest(ChunkInfo),
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}
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pub struct PeerConnection<H> {
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handler: H,
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addr: SocketAddr,
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info_hash: [u8; 20],
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peer_id: [u8; 20],
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}
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// async fn read_one<'a, R: AsyncReadExt + Unpin>(
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// mut reader: R,
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// read_buf: &'a mut Vec<u8>,
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// read_so_far: &mut usize,
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// ) -> anyhow::Result<(MessageBorrowed<'a>, usize)> {
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// loop {
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// match MessageBorrowed::deserialize(&read_buf[..*read_so_far]) {
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// Ok((msg, size)) => return Ok((msg, size)),
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// Err(MessageDeserializeError::NotEnoughData(d, _)) => {
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// if read_buf.len() < *read_so_far + d {
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// read_buf.reserve(d);
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// read_buf.resize(read_buf.capacity(), 0);
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// }
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// let size = reader
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// .read(&mut read_buf[*read_so_far..])
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// .await
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// .context("error reading from peer")?;
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// if size == 0 {
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// anyhow::bail!("disconnected while reading, read so far: {}", *read_so_far)
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// }
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// *read_so_far += size;
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// }
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// Err(e) => return Err(e.into()),
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// }
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// }
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// }
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macro_rules! read_one {
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($conn:ident, $read_buf:ident, $read_so_far:ident) => {{
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let (extended, size) = loop {
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match MessageBorrowed::deserialize(&$read_buf[..$read_so_far]) {
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Ok((msg, size)) => break (msg, size),
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Err(MessageDeserializeError::NotEnoughData(d, _)) => {
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if $read_buf.len() < $read_so_far + d {
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$read_buf.reserve(d);
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$read_buf.resize($read_buf.capacity(), 0);
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}
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let size = $conn
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.read(&mut $read_buf[$read_so_far..])
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.await
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.context("error reading from peer")?;
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if size == 0 {
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anyhow::bail!("disconnected while reading, read so far: {}", $read_so_far)
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}
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$read_so_far += size;
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}
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Err(e) => return Err(e.into()),
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}
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};
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(extended, size)
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}};
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}
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impl<H: PeerConnectionHandler> PeerConnection<H> {
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pub fn new(addr: SocketAddr, info_hash: [u8; 20], peer_id: [u8; 20], handler: H) -> Self {
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PeerConnection {
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handler,
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addr,
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info_hash,
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peer_id,
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}
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}
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pub fn into_handler(self) -> H {
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self.handler
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}
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pub async fn manage_peer(
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&self,
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mut outgoing_chan: tokio::sync::mpsc::UnboundedReceiver<WriterRequest>,
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) -> anyhow::Result<()> {
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use tokio::io::AsyncReadExt;
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use tokio::io::AsyncWriteExt;
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let mut conn = match timeout(
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Duration::from_secs(10),
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tokio::net::TcpStream::connect(self.addr),
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)
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.await
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{
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Ok(conn) => conn.context("error connecting")?,
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Err(_) => anyhow::bail!("timeout connecting to {}", self.addr),
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};
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let mut write_buf = Vec::<u8>::with_capacity(PIECE_MESSAGE_DEFAULT_LEN);
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let handshake = Handshake::new(self.info_hash, self.peer_id);
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handshake.serialize(&mut write_buf);
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conn.write_all(&write_buf)
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.await
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.context("error writing handshake")?;
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write_buf.clear();
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let mut read_buf = vec![0u8; PIECE_MESSAGE_DEFAULT_LEN * 2];
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let mut read_so_far = conn
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.read(&mut read_buf)
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.await
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.context("error reading handshake")?;
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if read_so_far == 0 {
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anyhow::bail!("bad handshake");
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}
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let (h, size) = Handshake::deserialize(&read_buf[..read_so_far])
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.map_err(|e| anyhow::anyhow!("error deserializing handshake: {:?}", e))?;
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debug!(
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"connected peer {}: {:?}",
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self.addr,
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try_decode_peer_id(h.peer_id)
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);
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if h.info_hash != self.info_hash {
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anyhow::bail!("info hash does not match");
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}
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let mut extended_handshake: Option<ExtendedHandshake<ByteString>> = None;
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let supports_extended = h.supports_extended();
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self.handler.on_handshake(h)?;
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if read_so_far > size {
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read_buf.copy_within(size..read_so_far, 0);
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}
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read_so_far -= size;
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if supports_extended {
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let my_extended =
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Message::Extended(ExtendedMessage::Handshake(ExtendedHandshake::new()));
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trace!(
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"sending extended handshake to {}: {:?}",
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self.addr,
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&my_extended
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);
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my_extended.serialize(&mut write_buf, None).unwrap();
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conn.write_all(&write_buf)
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.await
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.context("error writing extended handshake")?;
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write_buf.clear();
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let (extended, size) = read_one!(conn, read_buf, read_so_far);
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match extended {
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Message::Extended(ExtendedMessage::Handshake(h)) => {
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trace!("received from {}: {:?}", self.addr, &h);
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self.handler.on_extended_handshake(&h)?;
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extended_handshake = Some(h.clone_to_owned())
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}
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other => anyhow::bail!("expected extended handshake, but got {:?}", other),
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};
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if read_so_far > size {
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read_buf.copy_within(size..read_so_far, 0);
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}
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read_so_far -= size;
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}
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let (mut read_half, mut write_half) = tokio::io::split(conn);
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let writer = async move {
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let keep_alive_interval = Duration::from_secs(120);
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if self.handler.get_have_bytes() > 0 {
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if let Some(len) = self
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.handler
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.serialize_bitfield_message_to_buf(&mut write_buf)
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{
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write_half
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.write_all(&write_buf[..len])
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.await
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.context("error writing bitfield to peer")?;
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debug!("sent bitfield to {}", self.addr);
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}
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}
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loop {
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let req = match timeout(keep_alive_interval, outgoing_chan.recv()).await {
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Ok(Some(msg)) => msg,
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Ok(None) => {
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anyhow::bail!("closing writer, channel closed")
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}
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Err(_) => WriterRequest::Message(MessageOwned::KeepAlive),
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};
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let mut uploaded_add = None;
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let len = match &req {
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WriterRequest::Message(msg) => {
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msg.serialize(&mut write_buf, extended_handshake.as_ref())?
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}
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WriterRequest::ReadChunkRequest(chunk) => {
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// this whole section is an optimization
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write_buf.resize(PIECE_MESSAGE_DEFAULT_LEN, 0);
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let preamble_len = serialize_piece_preamble(&chunk, &mut write_buf);
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let full_len = preamble_len + chunk.size as usize;
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write_buf.resize(full_len, 0);
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self.handler
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.read_chunk(chunk, &mut write_buf[preamble_len..])
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.with_context(|| format!("error reading chunk {:?}", chunk))?;
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uploaded_add = Some(chunk.size);
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full_len
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}
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};
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debug!("sending to {}: {:?}, length={}", self.addr, &req, len);
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write_half
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.write_all(&write_buf[..len])
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.await
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.context("error writing the message to peer")?;
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write_buf.clear();
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if let Some(uploaded_add) = uploaded_add {
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self.handler.on_uploaded_bytes(uploaded_add)
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}
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}
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// For type inference.
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#[allow(unreachable_code)]
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Ok::<_, anyhow::Error>(())
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};
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let reader = async move {
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loop {
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let (message, size) = read_one!(read_half, read_buf, read_so_far);
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trace!("received from {}: {:?}", self.addr, &message);
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self.handler
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.on_received_message(message)
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.context("error in handler.on_received_message()")?;
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if read_so_far > size {
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read_buf.copy_within(size..read_so_far, 0);
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}
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read_so_far -= size;
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}
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// For type inference.
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#[allow(unreachable_code)]
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Ok::<_, anyhow::Error>(())
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};
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let r = tokio::select! {
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r = reader => {r}
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r = writer => {r}
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};
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debug!("{}: either reader or writer are done, exiting", self.addr);
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r
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}
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}
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