renet/renet
renet
/
renet
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Don't instantly ACK every received TCP segment. 

This is prohibited by RFC 1122. Instead, aggregate them, and respond
once in the egress function.

However, still instantly send challenge ACKs to trigger fast
retransmit.
This commit is contained in:
whitequark 2017-09-05 23:23:50 +00:00
parent bdb9c03081
commit 27a23ed3c3
1 changed files with 36 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
src/socket/tcp.rs
View File

@ -856,10 +856,18 @@ impl<'a> TcpSocket<'a> {
_ => {
let mut send_challenge_ack = false;
let window_start = self.remote_seq_no;
let window_end = window_start + self.rx_buffer.capacity();
let window_start = self.remote_seq_no + self.rx_buffer.len();
let window_end = self.remote_seq_no + self.rx_buffer.capacity();
let segment_start = repr.seq_number;
let segment_end = segment_start + repr.segment_len();
let segment_end = repr.seq_number + repr.segment_len();
if window_start == window_end && segment_start != segment_end {
net_debug!("[{}]{}:{}: non-zero-length segment with zero receive window, \
will only send an ACK",
self.debug_id, self.local_endpoint, self.remote_endpoint);
send_challenge_ack = true;
}
if !((window_start <= segment_start && segment_start <= window_end) ||
(window_start <= segment_end && segment_end <= window_end)) {
net_debug!("[{}]{}:{}: segment not in receive window \
@ -870,11 +878,11 @@ impl<'a> TcpSocket<'a> {
}
// For now, do not actually try to reassemble out-of-order segments.
if segment_start != window_start + self.rx_buffer.len() {
if segment_start != window_start {
net_debug!("[{}]{}:{}: out-of-order SEQ ({} not equal to {}), \
will send challenge ACK",
self.debug_id, self.local_endpoint, self.remote_endpoint,
segment_start, window_start + self.rx_buffer.len());
segment_start, window_start);
// Some segments between what we have last received and this segment
// went missing. Send a duplicate ACK; RFC 793 does not specify the behavior
// required when receiving a duplicate ACK, but in practice (see RFC 1122
@ -1092,16 +1100,9 @@ impl<'a> TcpSocket<'a> {
self.debug_id, self.local_endpoint, self.remote_endpoint,
repr.payload.len(), self.rx_buffer.len() + repr.payload.len());
self.rx_buffer.enqueue_slice(repr.payload);
// Send an acknowledgement.
self.remote_last_ack = Some(self.remote_seq_no + self.rx_buffer.len());
self.remote_last_win = self.rx_buffer.window() as u16;
Ok(Some(self.ack_reply(ip_repr, &repr)))
} else {
// No data to acknowledge; the logic to acknowledge SYN and FIN flags
// resides in dispatch().
Ok(None)
}
Ok(None)
}
fn seq_to_transmit(&self, control: TcpControl) -> bool {
@ -1664,12 +1665,13 @@ mod test {
ack_number: Some(LOCAL_SEQ + 1),
payload: &b"abcdef"[..],
..SEND_TEMPL
}, Ok(Some(TcpRepr {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1 + 6 + 1),
window_len: 58,
..RECV_TEMPL
})));
}]);
assert_eq!(s.state, State::CloseWait);
sanity!(s, TcpSocket {
remote_last_ack: Some(REMOTE_SEQ + 1 + 6 + 1),
@ -1881,12 +1883,13 @@ mod test {
ack_number: Some(LOCAL_SEQ + 1),
payload: &b"abcdef"[..],
..SEND_TEMPL
}, Ok(Some(TcpRepr {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1 + 6),
window_len: 58,
..RECV_TEMPL
})));
}]);
assert_eq!(s.rx_buffer.dequeue(6), &b"abcdef"[..]);
}
@ -2610,12 +2613,13 @@ mod test {
ack_number: Some(LOCAL_SEQ + 1),
payload: &b"abcdef"[..],
..SEND_TEMPL
}, Ok(Some(TcpRepr {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1 + 6),
window_len: 58,
..RECV_TEMPL
})));
}]);
s
}
@ -2644,12 +2648,13 @@ mod test {
ack_number: Some(LOCAL_SEQ + 1),
payload: &b"abcdef"[..],
..SEND_TEMPL
}, Ok(Some(TcpRepr {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1 + 6),
window_len: 58,
..RECV_TEMPL
})));
}]);
send!(s, TcpRepr {
seq_number: REMOTE_SEQ + 1 + 6 + 6,
ack_number: Some(LOCAL_SEQ + 1),
@ -2950,12 +2955,13 @@ mod test {
ack_number: Some(LOCAL_SEQ + 1),
payload: &b"abcdef"[..],
..SEND_TEMPL
}, Ok(Some(TcpRepr {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1 + 6),
window_len: 58,
..RECV_TEMPL
})));
}]);
}
#[test]
@ -2967,12 +2973,13 @@ mod test {
ack_number: Some(LOCAL_SEQ + 1),
payload: &b"abcdef"[..],
..SEND_TEMPL
}, Ok(Some(TcpRepr {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1 + 6),
window_len: 0,
..RECV_TEMPL
})));
}]);
send!(s, TcpRepr {
seq_number: REMOTE_SEQ + 1 + 6,
ack_number: Some(LOCAL_SEQ + 1),
@ -2995,12 +3002,13 @@ mod test {
ack_number: Some(LOCAL_SEQ + 1),
payload: &b"abcdef"[..],
..SEND_TEMPL
}, Ok(Some(TcpRepr {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1 + 6),
window_len: 0,
..RECV_TEMPL
})));
}]);
recv!(s, time 0, Err(Error::Exhausted));
assert_eq!(s.recv(3), Ok(&b"abc"[..]));
recv!(s, time 0, Ok(TcpRepr {