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tcp: make match on (state, control, ack) more readable.

master
Dario Nieuwenhuis 2021-10-06 01:03:13 +02:00
parent 6fee12dcee
commit aea021cfa9
1 changed files with 10 additions and 59 deletions
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69
src/socket/tcp.rs
View File

@ -1279,17 +1279,10 @@ impl<'a> TcpSocket<'a> {
let control_len = (sent_syn as usize) + (sent_fin as usize);
// Reject unacceptable acknowledgements.
match (self.state, repr) {
match (self.state, repr.control, repr.ack_number) {
// An RST received in response to initial SYN is acceptable if it acknowledges
// the initial SYN.
(
State::SynSent,
&TcpRepr {
control: TcpControl::Rst,
ack_number: None,
..
},
) => {
(State::SynSent, TcpControl::Rst, None) => {
net_debug!(
"{}:{}:{}: unacceptable RST (expecting RST|ACK) \
in response to initial SYN",
@ -1299,14 +1292,7 @@ impl<'a> TcpSocket<'a> {
);
return Err(Error::Dropped);
}
(
State::SynSent,
&TcpRepr {
control: TcpControl::Rst,
ack_number: Some(ack_number),
..
},
) => {
(State::SynSent, TcpControl::Rst, Some(ack_number)) => {
if ack_number != self.local_seq_no + 1 {
net_debug!(
"{}:{}:{}: unacceptable RST|ACK in response to initial SYN",
@ -1318,35 +1304,13 @@ impl<'a> TcpSocket<'a> {
}
}
// Any other RST need only have a valid sequence number.
(
_,
&TcpRepr {
control: TcpControl::Rst,
..
},
) => (),
(_, TcpControl::Rst, _) => (),
// The initial SYN cannot contain an acknowledgement.
(
State::Listen,
&TcpRepr {
ack_number: None, ..
},
) => (),
(State::Listen, _, None) => (),
// This case is handled above.
(
State::Listen,
&TcpRepr {
ack_number: Some(_),
..
},
) => unreachable!(),
(State::Listen, _, Some(_)) => unreachable!(),
// Every packet after the initial SYN must be an acknowledgement.
(
_,
&TcpRepr {
ack_number: None, ..
},
) => {
(_, _, None) => {
net_debug!(
"{}:{}:{}: expecting an ACK",
self.meta.handle,
@ -1356,14 +1320,7 @@ impl<'a> TcpSocket<'a> {
return Err(Error::Dropped);
}
// SYN|ACK in the SYN-SENT state must have the exact ACK number.
(
State::SynSent,
&TcpRepr {
control: TcpControl::Syn,
ack_number: Some(ack_number),
..
},
) => {
(State::SynSent, TcpControl::Syn, Some(ack_number)) => {
if ack_number != self.local_seq_no + 1 {
net_debug!(
"{}:{}:{}: unacceptable SYN|ACK in response to initial SYN",
@ -1375,7 +1332,7 @@ impl<'a> TcpSocket<'a> {
}
}
// Anything else in the SYN-SENT state is invalid.
(State::SynSent, _) => {
(State::SynSent, _, _) => {
net_debug!(
"{}:{}:{}: expecting a SYN|ACK",
self.meta.handle,
@ -1386,13 +1343,7 @@ impl<'a> TcpSocket<'a> {
return Err(Error::Dropped);
}
// Every acknowledgement must be for transmitted but unacknowledged data.
(
_,
&TcpRepr {
ack_number: Some(ack_number),
..
},
) => {
(_, _, Some(ack_number)) => {
let unacknowledged = self.tx_buffer.len() + control_len;
// Acceptable ACK range (both inclusive)