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Add support for TCP MSS option in TCP representation.

This commit is contained in:
whitequark 2017-01-27 01:09:34 +00:00
parent 4c3f454902
commit 077513fda6
3 changed files with 101 additions and 40 deletions
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17
src/iface/ethernet.rs
View File

@ -230,14 +230,15 @@ impl<'a, 'b, 'c, DeviceT: Device + 'a> Interface<'a, 'b, 'c, DeviceT> {
let tcp_packet = try!(TcpPacket::new(ipv4_packet.payload()));
if !tcp_packet.rst() {
let tcp_reply_repr = TcpRepr {
src_port: tcp_packet.dst_port(),
dst_port: tcp_packet.src_port(),
control: TcpControl::Rst,
seq_number: tcp_packet.ack_number(),
ack_number: Some(tcp_packet.seq_number() +
tcp_packet.segment_len()),
window_len: 0,
payload: &[]
src_port: tcp_packet.dst_port(),
dst_port: tcp_packet.src_port(),
control: TcpControl::Rst,
seq_number: tcp_packet.ack_number(),
ack_number: Some(tcp_packet.seq_number() +
tcp_packet.segment_len()),
window_len: 0,
max_seg_size: None,
payload: &[]
};
let ipv4_reply_repr = Ipv4Repr {
src_addr: dst_addr,

21
src/socket/tcp.rs
View File

@ -821,13 +821,14 @@ impl<'a> TcpSocket<'a> {
if self.remote_endpoint.is_unspecified() { return Err(Error::Exhausted) }
let mut repr = TcpRepr {
src_port: self.local_endpoint.port,
dst_port: self.remote_endpoint.port,
control: TcpControl::None,
seq_number: self.local_seq_no,
ack_number: None,
window_len: self.rx_buffer.window() as u16,
payload: &[]
src_port: self.local_endpoint.port,
dst_port: self.remote_endpoint.port,
control: TcpControl::None,
seq_number: self.local_seq_no,
ack_number: None,
window_len: self.rx_buffer.window() as u16,
max_seg_size: None,
payload: &[]
};
if self.state == State::Closed {
@ -1053,13 +1054,15 @@ mod test {
src_port: REMOTE_PORT, dst_port: LOCAL_PORT,
control: TcpControl::None,
seq_number: TcpSeqNumber(0), ack_number: Some(TcpSeqNumber(0)),
window_len: 256, payload: &[]
window_len: 256, max_seg_size: None,
payload: &[]
};
const RECV_TEMPL: TcpRepr<'static> = TcpRepr {
src_port: LOCAL_PORT, dst_port: REMOTE_PORT,
control: TcpControl::None,
seq_number: TcpSeqNumber(0), ack_number: Some(TcpSeqNumber(0)),
window_len: 64, payload: &[]
window_len: 64, max_seg_size: None,
payload: &[]
};
fn send(socket: &mut TcpSocket, timestamp: u64, repr: &TcpRepr) -> Result<(), Error> {

103
src/wire/tcp.rs
View File

@ -576,13 +576,14 @@ pub enum Control {
/// A high-level representation of a Transmission Control Protocol packet.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct Repr<'a> {
pub src_port: u16,
pub dst_port: u16,
pub control: Control,
pub seq_number: SeqNumber,
pub ack_number: Option<SeqNumber>,
pub window_len: u16,
pub payload: &'a [u8]
pub src_port: u16,
pub dst_port: u16,
pub control: Control,
pub seq_number: SeqNumber,
pub ack_number: Option<SeqNumber>,
pub window_len: u16,
pub max_seg_size: Option<u16>,
pub payload: &'a [u8]
}
impl<'a> Repr<'a> {
@ -615,20 +616,44 @@ impl<'a> Repr<'a> {
// however, most deployed systems (e.g. Linux) are *not* standards-compliant, and would
// cut the byte at the urgent pointer from the stream.
let mut max_seg_size = None;
let mut options = packet.options();
while options.len() > 0 {
let (next_options, option) = TcpOption::parse(options)?;
match option {
TcpOption::EndOfList => break,
TcpOption::NoOperation => (),
TcpOption::MaxSegmentSize(value) =>
max_seg_size = Some(value),
_ => ()
}
options = next_options;
}
Ok(Repr {
src_port: packet.src_port(),
dst_port: packet.dst_port(),
control: control,
seq_number: packet.seq_number(),
ack_number: ack_number,
window_len: packet.window_len(),
payload: packet.payload()
src_port: packet.src_port(),
dst_port: packet.dst_port(),
control: control,
seq_number: packet.seq_number(),
ack_number: ack_number,
window_len: packet.window_len(),
max_seg_size: max_seg_size,
payload: packet.payload()
})
}
/// Return the length of a header that will be emitted from this high-level representation.
pub fn header_len(&self) -> usize {
let mut length = field::URGENT.end;
if self.max_seg_size.is_some() {
length += 4
}
length
}
/// Return the length of a packet that will be emitted from this high-level representation.
pub fn buffer_len(&self) -> usize {
field::URGENT.end + self.payload.len()
self.header_len() + self.payload.len()
}
/// Emit a high-level representation into a Transmission Control Protocol packet.
@ -641,7 +666,7 @@ impl<'a> Repr<'a> {
packet.set_seq_number(self.seq_number);
packet.set_ack_number(self.ack_number.unwrap_or(SeqNumber(0)));
packet.set_window_len(self.window_len);
packet.set_header_len(field::URGENT.end as u8);
packet.set_header_len(self.header_len() as u8);
packet.clear_flags();
match self.control {
Control::None => (),
@ -650,6 +675,15 @@ impl<'a> Repr<'a> {
Control::Rst => packet.set_rst(true)
}
packet.set_ack(self.ack_number.is_some());
{
let mut options = packet.options_mut();
if let Some(value) = self.max_seg_size {
let tmp = options; options = TcpOption::MaxSegmentSize(value).emit(tmp);
}
if options.len() > 0 {
TcpOption::EndOfList.emit(options);
}
}
packet.payload_mut().copy_from_slice(self.payload);
packet.fill_checksum(src_addr, dst_addr)
}
@ -676,6 +710,25 @@ impl<'a, T: AsRef<[u8]> + ?Sized> fmt::Display for Packet<&'a T> {
try!(write!(f, " urg={}", self.urgent_at()))
}
try!(write!(f, " len={}", self.payload().len()));
let mut options = self.options();
while options.len() > 0 {
let (next_options, option) =
match TcpOption::parse(options) {
Ok(res) => res,
Err(err) => return write!(f, " ({})", err)
};
match option {
TcpOption::EndOfList => break,
TcpOption::NoOperation => (),
TcpOption::MaxSegmentSize(value) =>
try!(write!(f, " mss={}", value)),
TcpOption::WindowScale(value) =>
try!(write!(f, " ws={}", value)),
TcpOption::Unknown { kind, .. } =>
try!(write!(f, " opt({})", kind)),
}
options = next_options;
}
Ok(())
}
}
@ -696,6 +749,9 @@ impl<'a> fmt::Display for Repr<'a> {
}
try!(write!(f, " win={}", self.window_len));
try!(write!(f, " len={}", self.payload.len()));
if let Some(max_seg_size) = self.max_seg_size {
try!(write!(f, " mss={}", max_seg_size));
}
Ok(())
}
}
@ -791,13 +847,14 @@ mod test {
fn packet_repr() -> Repr<'static> {
Repr {
src_port: 48896,
dst_port: 80,
seq_number: SeqNumber(0x01234567),
ack_number: None,
window_len: 0x0123,
control: Control::Syn,
payload: &PAYLOAD_BYTES
src_port: 48896,
dst_port: 80,
seq_number: SeqNumber(0x01234567),
ack_number: None,
window_len: 0x0123,
control: Control::Syn,
max_seg_size: None,
payload: &PAYLOAD_BYTES
}
}