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Fix TCP FIN,ACK behaviour

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This commit is contained in:
_Frky 2021-12-31 11:21:33 +01:00
parent 797c30ce91
commit 0749e23eea
1 changed files with 11 additions and 3 deletions
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14
src/layer_4/tcp.rs
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@ -78,10 +78,18 @@ pub fn repl<'a, 'b>(
/* answer here when server needs to speak first after handshake */ /* answer here when server needs to speak first after handshake */
return None; return None;
} }
/* Answer to RST and FIN: nothing */ /* Answer to RST: nothing */
flags if (flags == TcpFlags::RST || flags == (TcpFlags::FIN | TcpFlags::ACK)) => { flags if flags == TcpFlags::RST => {
return None; return None;
} }
/* Answer to FIN,ACK with FIN,ACK */
flags if flags == (TcpFlags::FIN | TcpFlags::ACK) => {
tcp_repl = MutableTcpPacket::owned(vec![0; MutableTcpPacket::minimum_packet_size()])
.expect("error constructing a TCP packet");
tcp_repl.set_flags(TcpFlags::FIN | TcpFlags::ACK);
tcp_repl.set_acknowledgement(tcp_req.get_sequence() + 1);
tcp_repl.set_sequence(tcp_req.get_acknowledgement());
}
/* Answer to SYN */ /* Answer to SYN */
flags if flags & TcpFlags::SYN == TcpFlags::SYN => { flags if flags & TcpFlags::SYN == TcpFlags::SYN => {
tcp_repl = MutableTcpPacket::owned(vec![0; MutableTcpPacket::minimum_packet_size()]) tcp_repl = MutableTcpPacket::owned(vec![0; MutableTcpPacket::minimum_packet_size()])
@ -165,7 +173,7 @@ mod tests {
assert!(tcp_repl.get_flags() == (TcpFlags::FIN | TcpFlags::ACK)); assert!(tcp_repl.get_flags() == (TcpFlags::FIN | TcpFlags::ACK));
/* check reply seq and ack */ /* check reply seq and ack */
assert!(tcp_repl.get_sequence() == ack); assert!(tcp_repl.get_sequence() == ack);
assert!(tcp_repl.get_acknowledgement() == seq); assert!(tcp_repl.get_acknowledgement() == seq + 1);
} }
#[test] #[test]