Correctly treat TCP ACKs that acknowledge both data and a FIN.

This commit is contained in:
whitequark 2017-01-23 21:02:28 +00:00
parent 368b954a3c
commit 497aa5919a
1 changed files with 48 additions and 18 deletions

View File

@ -575,6 +575,18 @@ impl<'a> TcpSocket<'a> {
if !self.remote_endpoint.addr.is_unspecified() &&
self.remote_endpoint.addr != ip_repr.src_addr() { return Err(Error::Rejected) }
// Consider how much the sequence number space differs from the transmit buffer space.
let (sent_syn, sent_fin) = match self.state {
// In SYN-SENT or SYN-RECEIVED, we've just sent a SYN.
State::SynSent | State::SynReceived => (true, false),
// In FIN-WAIT-1, LAST-ACK, or CLOSING, we've just sent a FIN.
State::FinWait1 | State::LastAck | State::Closing => (false, true),
// In all other states we've already got acknowledgemetns for
// all of the control flags we sent.
_ => (false, false)
};
let control_len = (sent_syn as usize) + (sent_fin as usize);
// Reject unacceptable acknowledgements.
match (self.state, repr) {
// The initial SYN (or whatever) cannot contain an acknowledgement.
@ -609,16 +621,7 @@ impl<'a> TcpSocket<'a> {
return Err(Error::Malformed)
}
// Every acknowledgement must be for transmitted but unacknowledged data.
(state, TcpRepr { ack_number: Some(ack_number), .. }) => {
let control_len = match state {
// In SYN-SENT or SYN-RECEIVED, we've just sent a SYN.
State::SynSent | State::SynReceived => 1,
// In FIN-WAIT-1, LAST-ACK, or CLOSING, we've just sent a FIN.
State::FinWait1 | State::LastAck | State::Closing => 1,
// In all other states we've already got acknowledgemetns for
// all of the control flags we sent.
_ => 0
};
(_, TcpRepr { ack_number: Some(ack_number), .. }) => {
let unacknowledged = self.tx_buffer.len() + control_len;
if !(ack_number >= self.local_seq_no &&
ack_number <= (self.local_seq_no + unacknowledged)) {
@ -708,7 +711,6 @@ impl<'a> TcpSocket<'a> {
// ACK packets in the SYN-RECEIVED state change it to ESTABLISHED.
(State::SynReceived, TcpRepr { control: TcpControl::None, .. }) => {
self.local_seq_no += 1;
self.set_state(State::Established);
self.retransmit.reset();
}
@ -725,7 +727,6 @@ impl<'a> TcpSocket<'a> {
// ACK packets in FIN-WAIT-1 state change it to FIN-WAIT-2.
(State::FinWait1, TcpRepr { control: TcpControl::None, .. }) => {
self.local_seq_no += 1;
self.set_state(State::FinWait2);
}
@ -745,7 +746,6 @@ impl<'a> TcpSocket<'a> {
// ACK packets in CLOSING state change it to TIME-WAIT.
(State::Closing, TcpRepr { control: TcpControl::None, .. }) => {
self.local_seq_no += 1;
self.set_state(State::TimeWait);
self.retransmit.reset();
}
@ -758,7 +758,6 @@ impl<'a> TcpSocket<'a> {
// Clear the remote endpoint, or we'll send an RST there.
self.set_state(State::Closed);
self.remote_endpoint = IpEndpoint::default();
self.local_seq_no += 1;
}
_ => {
@ -770,13 +769,23 @@ impl<'a> TcpSocket<'a> {
// Dequeue acknowledged octets.
if let Some(ack_number) = repr.ack_number {
let ack_length = ack_number - self.local_seq_no;
if ack_length > 0 {
let mut ack_len = ack_number - self.local_seq_no;
// There could have been no data sent before the SYN, so we always remove it
// from the sequence space.
if sent_syn {
ack_len -= 1
}
// We could've sent data before the FIN, so only remove FIN from the sequence
// space if all of that data is acknowledged.
if sent_fin && self.tx_buffer.len() + 1 == ack_len {
ack_len -= 1
}
if ack_len > 0 {
net_trace!("[{}]{}:{}: tx buffer: dequeueing {} octets (now {})",
self.debug_id, self.local_endpoint, self.remote_endpoint,
ack_length, self.tx_buffer.len() - ack_length);
ack_len, self.tx_buffer.len() - ack_len);
}
self.tx_buffer.advance(ack_length);
self.tx_buffer.advance(ack_len);
self.local_seq_no = ack_number;
}
@ -1962,6 +1971,27 @@ mod test {
}])
}
#[test]
fn test_mutual_close_with_data() {
let mut s = socket_established();
s.send_slice(b"abcdef").unwrap();
s.close();
assert_eq!(s.state, State::FinWait1);
recv!(s, [TcpRepr {
control: TcpControl::Fin,
seq_number: LOCAL_SEQ + 1,
ack_number: Some(REMOTE_SEQ + 1),
payload: &b"abcdef"[..],
..RECV_TEMPL
}]);
send!(s, TcpRepr {
control: TcpControl::Fin,
seq_number: REMOTE_SEQ + 1,
ack_number: Some(LOCAL_SEQ + 1 + 6 + 1),
..SEND_TEMPL
});
}
// =========================================================================================//
// Tests for retransmission on packet loss.
// =========================================================================================//