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Send a challenge ACK in response to an unacceptable TCP ACK.

This commit is contained in:
whitequark 2017-09-08 00:06:31 +00:00
parent 844843c4bc
commit 9b242c7099
1 changed files with 9 additions and 4 deletions
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13
src/socket/tcp.rs
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@ -734,19 +734,20 @@ impl<'a> TcpSocket<'a> {
// Every acknowledgement must be for transmitted but unacknowledged data. // Every acknowledgement must be for transmitted but unacknowledged data.
(_, &TcpRepr { ack_number: Some(ack_number), .. }) => { (_, &TcpRepr { ack_number: Some(ack_number), .. }) => {
let unacknowledged = self.tx_buffer.len() + control_len; let unacknowledged = self.tx_buffer.len() + control_len;
if ack_number < self.local_seq_no { if ack_number < self.local_seq_no {
net_debug!("[{}]{}:{}: duplicate ACK ({} not in {}...{})", net_debug!("[{}]{}:{}: duplicate ACK ({} not in {}...{})",
self.debug_id, self.local_endpoint, self.remote_endpoint, self.debug_id, self.local_endpoint, self.remote_endpoint,
ack_number, self.local_seq_no, self.local_seq_no + unacknowledged); ack_number, self.local_seq_no, self.local_seq_no + unacknowledged);
// FIXME: instead of waiting for the retransmit timer to kick in, // FIXME: implement fast retransmit
// reset it here.
return Err(Error::Dropped) return Err(Error::Dropped)
} }
if ack_number > self.local_seq_no + unacknowledged { if ack_number > self.local_seq_no + unacknowledged {
net_debug!("[{}]{}:{}: unacceptable ACK ({} not in {}...{})", net_debug!("[{}]{}:{}: unacceptable ACK ({} not in {}...{})",
self.debug_id, self.local_endpoint, self.remote_endpoint, self.debug_id, self.local_endpoint, self.remote_endpoint,
ack_number, self.local_seq_no, self.local_seq_no + unacknowledged); ack_number, self.local_seq_no, self.local_seq_no + unacknowledged);
return Err(Error::Dropped) return Ok(Some(self.ack_reply(ip_repr, &repr)))
} }
} }
} }
@ -1870,7 +1871,11 @@ mod test {
seq_number: REMOTE_SEQ + 1, seq_number: REMOTE_SEQ + 1,
ack_number: Some(LOCAL_SEQ + 10), ack_number: Some(LOCAL_SEQ + 10),
..SEND_TEMPL ..SEND_TEMPL
}, Err(Error::Dropped)); }, Ok(Some(TcpRepr {
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1),
..RECV_TEMPL
})));
assert_eq!(s.local_seq_no, LOCAL_SEQ + 1); assert_eq!(s.local_seq_no, LOCAL_SEQ + 1);
} }