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Only trigger fast retransmit for data to send 

This fixes entering a loop when both endpoints
are stuck in retransmission.

https://github.com/m-labs/smoltcp/issues/224

Closes: #233
Approved by: whitequark
This commit is contained in:
Kai Lüke 2018-06-12 15:19:48 +09:00 committed by Homu
parent 272baab3ef
commit b23df24a2a
1 changed files with 34 additions and 3 deletions
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37
src/socket/tcp.rs
View File

@ -1157,9 +1157,10 @@ impl<'a> TcpSocket<'a> {
// Duplicate ACK if payload empty and ACK doesn't move send window ->
// Increment duplicate ACK count and set for retransmit if we just recived
// the third duplicate ACK
Some(ref mut last_rx_ack) if
Some(ref last_rx_ack) if
repr.payload.len() == 0 &&
*last_rx_ack == ack_number => {
*last_rx_ack == ack_number &&
ack_number < self.remote_last_seq => {
// Increment duplicate ACK count
self.local_rx_dup_acks = self.local_rx_dup_acks.saturating_add(1);
@ -3326,6 +3327,14 @@ mod test {
fn test_fast_retransmit_duplicate_detection_with_data() {
let mut s = socket_established();
s.send_slice(b"abc").unwrap(); // This is lost
recv!(s, time 1000, Ok(TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1),
payload: &b"abc"[..],
..RECV_TEMPL
}));
// Normal ACK of previously recieved segment
send!(s, TcpRepr {
seq_number: REMOTE_SEQ + 1,
@ -3345,6 +3354,9 @@ mod test {
..SEND_TEMPL
});
assert_eq!(s.local_rx_dup_acks, 2,
"duplicate ACK counter is not set");
// This packet has content, hence should not be detected
// as a duplicate ACK and should reset the duplicate ACK count
send!(s, TcpRepr {
@ -3355,7 +3367,7 @@ mod test {
});
recv!(s, [TcpRepr {
seq_number: LOCAL_SEQ + 1,
seq_number: LOCAL_SEQ + 1 + 3,
ack_number: Some(REMOTE_SEQ + 1 + 6),
window_len: 58,
..RECV_TEMPL
@ -3377,6 +3389,17 @@ mod test {
..SEND_TEMPL
});
// First duplicate, should not be counted as there is nothing to resend
send!(s, time 0, TcpRepr {
seq_number: REMOTE_SEQ + 1,
ack_number: Some(LOCAL_SEQ + 1),
window_len: 6,
..SEND_TEMPL
});
assert_eq!(s.local_rx_dup_acks, 0,
"duplicate ACK counter is set but wound not transmit data");
// Send a long string of text divided into several packets
// because of previously recieved "window_len"
s.send_slice(b"xxxxxxyyyyyywwwwwwzzzzzz").unwrap();
@ -3444,6 +3467,14 @@ mod test {
fn test_fast_retransmit_dup_acks_counter() {
let mut s = socket_established();
s.send_slice(b"abc").unwrap(); // This is lost
recv!(s, time 0, Ok(TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1),
payload: &b"abc"[..],
..RECV_TEMPL
}));
send!(s, time 0, TcpRepr {
seq_number: REMOTE_SEQ + 1,
ack_number: Some(LOCAL_SEQ + 1),