renet/src/wire/tcp.rs

635 lines
21 KiB
Rust
Raw Normal View History

2016-12-20 21:16:29 +08:00
use core::fmt;
2016-12-19 05:42:44 +08:00
use byteorder::{ByteOrder, NetworkEndian};
use Error;
use super::{IpProtocol, IpAddress};
2016-12-19 05:42:44 +08:00
use super::ip::checksum;
/// A read/write wrapper around an Transmission Control Protocol packet buffer.
#[derive(Debug)]
pub struct Packet<T: AsRef<[u8]>> {
buffer: T
}
mod field {
#![allow(non_snake_case)]
use wire::field::*;
pub const SRC_PORT: Field = 0..2;
pub const DST_PORT: Field = 2..4;
pub const SEQ_NUM: Field = 4..8;
pub const ACK_NUM: Field = 8..12;
pub const FLAGS: Field = 12..14;
pub const WIN_SIZE: Field = 14..16;
pub const CHECKSUM: Field = 16..18;
pub const URGENT: Field = 18..20;
pub const FLG_FIN: u16 = 0x001;
pub const FLG_SYN: u16 = 0x002;
pub const FLG_RST: u16 = 0x004;
pub const FLG_PSH: u16 = 0x008;
pub const FLG_ACK: u16 = 0x010;
pub const FLG_URG: u16 = 0x020;
pub const FLG_ECE: u16 = 0x040;
pub const FLG_CWR: u16 = 0x080;
pub const FLG_NS: u16 = 0x100;
}
impl<T: AsRef<[u8]>> Packet<T> {
/// Wrap a buffer with a TCP packet. Returns an error if the buffer
/// is too small to contain one.
pub fn new(buffer: T) -> Result<Packet<T>, Error> {
let len = buffer.as_ref().len();
if len < field::URGENT.end {
Err(Error::Truncated)
} else {
Ok(Packet { buffer: buffer })
}
}
/// Consumes the packet, returning the underlying buffer.
pub fn into_inner(self) -> T {
self.buffer
}
/// Return the source port field.
#[inline(always)]
pub fn src_port(&self) -> u16 {
let data = self.buffer.as_ref();
NetworkEndian::read_u16(&data[field::SRC_PORT])
}
/// Return the destination port field.
#[inline(always)]
pub fn dst_port(&self) -> u16 {
let data = self.buffer.as_ref();
NetworkEndian::read_u16(&data[field::DST_PORT])
}
/// Return the sequence number field.
#[inline(always)]
pub fn seq_number(&self) -> i32 {
2016-12-19 05:42:44 +08:00
let data = self.buffer.as_ref();
NetworkEndian::read_i32(&data[field::SEQ_NUM])
2016-12-19 05:42:44 +08:00
}
/// Return the acknowledgement number field.
#[inline(always)]
pub fn ack_number(&self) -> i32 {
2016-12-19 05:42:44 +08:00
let data = self.buffer.as_ref();
NetworkEndian::read_i32(&data[field::ACK_NUM])
2016-12-19 05:42:44 +08:00
}
/// Return the FIN flag.
#[inline(always)]
pub fn fin(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_FIN != 0
}
/// Return the SYN flag.
#[inline(always)]
pub fn syn(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_SYN != 0
}
/// Return the RST flag.
#[inline(always)]
pub fn rst(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_RST != 0
}
/// Return the PSH flag.
#[inline(always)]
pub fn psh(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_PSH != 0
}
/// Return the ACK flag.
#[inline(always)]
pub fn ack(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_ACK != 0
}
/// Return the URG flag.
#[inline(always)]
pub fn urg(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_URG != 0
}
/// Return the ECE flag.
#[inline(always)]
pub fn ece(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_ECE != 0
}
/// Return the CWR flag.
#[inline(always)]
pub fn cwr(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_CWR != 0
}
/// Return the NS flag.
#[inline(always)]
pub fn ns(&self) -> bool {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
raw & field::FLG_NS != 0
}
/// Return the header length, in octets.
#[inline(always)]
pub fn header_len(&self) -> u8 {
let data = self.buffer.as_ref();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
((raw >> 12) * 4) as u8
}
/// Return the window size field.
#[inline(always)]
pub fn window_len(&self) -> u16 {
let data = self.buffer.as_ref();
NetworkEndian::read_u16(&data[field::WIN_SIZE])
}
/// Return the checksum field.
#[inline(always)]
pub fn checksum(&self) -> u16 {
let data = self.buffer.as_ref();
NetworkEndian::read_u16(&data[field::CHECKSUM])
}
/// Return the urgent pointer field.
#[inline(always)]
pub fn urgent_at(&self) -> u16 {
let data = self.buffer.as_ref();
NetworkEndian::read_u16(&data[field::URGENT])
}
/// Validate the packet checksum.
///
/// # Panics
/// This function panics unless `src_addr` and `dst_addr` belong to the same family,
/// and that family is IPv4 or IPv6.
pub fn verify_checksum(&self, src_addr: &IpAddress, dst_addr: &IpAddress) -> bool {
2016-12-19 05:42:44 +08:00
let data = self.buffer.as_ref();
checksum::combine(&[
checksum::pseudo_header(src_addr, dst_addr, IpProtocol::Tcp,
2016-12-19 05:42:44 +08:00
data.len() as u32),
checksum::data(data)
]) == !0
}
}
impl<'a, T: AsRef<[u8]> + ?Sized> Packet<&'a T> {
/// Return a pointer to the payload.
#[inline(always)]
pub fn payload(&self) -> &'a [u8] {
let header_len = self.header_len() as usize;
let data = self.buffer.as_ref();
&data[header_len..]
}
}
impl<T: AsRef<[u8]> + AsMut<[u8]>> Packet<T> {
/// Set the source port field.
#[inline(always)]
pub fn set_src_port(&mut self, value: u16) {
let mut data = self.buffer.as_mut();
NetworkEndian::write_u16(&mut data[field::SRC_PORT], value)
}
/// Set the destination port field.
#[inline(always)]
pub fn set_dst_port(&mut self, value: u16) {
let mut data = self.buffer.as_mut();
NetworkEndian::write_u16(&mut data[field::DST_PORT], value)
}
/// Set the sequence number field.
#[inline(always)]
pub fn set_seq_number(&mut self, value: i32) {
2016-12-19 05:42:44 +08:00
let mut data = self.buffer.as_mut();
NetworkEndian::write_i32(&mut data[field::SEQ_NUM], value)
2016-12-19 05:42:44 +08:00
}
/// Set the acknowledgement number field.
#[inline(always)]
pub fn set_ack_number(&mut self, value: i32) {
2016-12-19 05:42:44 +08:00
let mut data = self.buffer.as_mut();
NetworkEndian::write_i32(&mut data[field::ACK_NUM], value)
2016-12-19 05:42:44 +08:00
}
/// Clear the entire flags field.
#[inline(always)]
pub fn clear_flags(&mut self) {
let data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = raw & !0x0fff;
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
2016-12-19 05:42:44 +08:00
/// Set the FIN flag.
#[inline(always)]
pub fn set_fin(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_FIN } else { raw & !field::FLG_FIN };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the SYN flag.
#[inline(always)]
pub fn set_syn(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_SYN } else { raw & !field::FLG_SYN };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the RST flag.
#[inline(always)]
pub fn set_rst(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_RST } else { raw & !field::FLG_RST };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the PSH flag.
#[inline(always)]
pub fn set_psh(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_PSH } else { raw & !field::FLG_PSH };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the ACK flag.
#[inline(always)]
pub fn set_ack(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_ACK } else { raw & !field::FLG_ACK };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the URG flag.
#[inline(always)]
pub fn set_urg(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_URG } else { raw & !field::FLG_URG };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the ECE flag.
#[inline(always)]
pub fn set_ece(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_ECE } else { raw & !field::FLG_ECE };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the CWR flag.
#[inline(always)]
pub fn set_cwr(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_CWR } else { raw & !field::FLG_CWR };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the NS flag.
#[inline(always)]
pub fn set_ns(&mut self, value: bool) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = if value { raw | field::FLG_NS } else { raw & !field::FLG_NS };
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Set the header length, in octets.
#[inline(always)]
pub fn set_header_len(&mut self, value: u8) {
let mut data = self.buffer.as_mut();
let raw = NetworkEndian::read_u16(&data[field::FLAGS]);
let raw = (raw & !0xf000) | ((value as u16) / 4) << 12;
NetworkEndian::write_u16(&mut data[field::FLAGS], raw)
}
/// Return the window size field.
#[inline(always)]
pub fn set_window_len(&mut self, value: u16) {
let mut data = self.buffer.as_mut();
NetworkEndian::write_u16(&mut data[field::WIN_SIZE], value)
}
/// Set the checksum field.
#[inline(always)]
pub fn set_checksum(&mut self, value: u16) {
let mut data = self.buffer.as_mut();
NetworkEndian::write_u16(&mut data[field::CHECKSUM], value)
}
/// Set the urgent pointer field.
#[inline(always)]
pub fn set_urgent_at(&mut self, value: u16) {
let mut data = self.buffer.as_mut();
NetworkEndian::write_u16(&mut data[field::URGENT], value)
}
/// Compute and fill in the header checksum.
///
/// # Panics
/// This function panics unless `src_addr` and `dst_addr` belong to the same family,
/// and that family is IPv4 or IPv6.
pub fn fill_checksum(&mut self, src_addr: &IpAddress, dst_addr: &IpAddress) {
2016-12-19 05:42:44 +08:00
self.set_checksum(0);
let checksum = {
let data = self.buffer.as_ref();
!checksum::combine(&[
checksum::pseudo_header(src_addr, dst_addr, IpProtocol::Tcp,
2016-12-19 05:42:44 +08:00
data.len() as u32),
checksum::data(data)
])
};
self.set_checksum(checksum)
}
}
impl<'a, T: AsRef<[u8]> + AsMut<[u8]> + ?Sized> Packet<&'a mut T> {
/// Return a mutable pointer to the payload data.
#[inline(always)]
pub fn payload_mut(&mut self) -> &mut [u8] {
let header_len = self.header_len() as usize;
let mut data = self.buffer.as_mut();
&mut data[header_len..]
}
}
/// A high-level representation of a Transmission Control Protocol packet.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct Repr<'a> {
2016-12-20 21:44:41 +08:00
pub src_port: u16,
pub dst_port: u16,
pub control: Control,
pub seq_number: i32,
pub ack_number: Option<i32>,
2016-12-20 21:44:41 +08:00
pub window_len: u16,
pub payload: &'a [u8]
}
/// The control flags of a Transmission Control Protocol packet.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum Control {
None,
Syn,
Fin,
Rst
}
impl<'a> Repr<'a> {
/// Parse a Transmission Control Protocol packet and return a high-level representation.
pub fn parse<T: ?Sized>(packet: &Packet<&'a T>,
src_addr: &IpAddress,
dst_addr: &IpAddress) -> Result<Repr<'a>, Error>
where T: AsRef<[u8]> {
// Source and destination ports must be present.
if packet.src_port() == 0 { return Err(Error::Malformed) }
if packet.dst_port() == 0 { return Err(Error::Malformed) }
// Valid checksum is expected...
if !packet.verify_checksum(src_addr, dst_addr) { return Err(Error::Checksum) }
let control =
match (packet.syn(), packet.fin(), packet.rst()) {
(false, false, false) => Control::None,
(true, false, false) => Control::Syn,
(false, true, false) => Control::Fin,
(false, false, true ) => Control::Rst,
_ => return Err(Error::Malformed)
};
let ack_number =
match packet.ack() {
true => Some(packet.ack_number()),
false => None
};
// The PSH flag is ignored.
// The URG flag and the urgent field is ignored. This behavior is standards-compliant,
// however, most deployed systems (e.g. Linux) are *not* standards-compliant, and would
// cut the byte at the urgent pointer from the stream.
Ok(Repr {
src_port: packet.src_port(),
dst_port: packet.dst_port(),
2016-12-20 21:16:29 +08:00
control: control,
seq_number: packet.seq_number(),
ack_number: ack_number,
window_len: packet.window_len(),
payload: packet.payload()
})
}
/// 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()
}
/// Emit a high-level representation into a Transmission Control Protocol packet.
pub fn emit<T: ?Sized>(&self, packet: &mut Packet<&mut T>,
src_addr: &IpAddress,
dst_addr: &IpAddress)
where T: AsRef<[u8]> + AsMut<[u8]> {
packet.set_src_port(self.src_port);
packet.set_dst_port(self.dst_port);
packet.set_seq_number(self.seq_number);
packet.set_ack_number(self.ack_number.unwrap_or(0));
packet.set_window_len(self.window_len);
packet.set_header_len(field::URGENT.end as u8);
packet.clear_flags();
match self.control {
Control::None => (),
Control::Syn => packet.set_syn(true),
Control::Fin => packet.set_fin(true),
Control::Rst => packet.set_rst(true)
}
packet.set_ack(self.ack_number.is_some());
packet.payload_mut().copy_from_slice(self.payload);
packet.fill_checksum(src_addr, dst_addr)
}
}
2016-12-20 21:16:29 +08:00
impl<'a, T: AsRef<[u8]> + ?Sized> fmt::Display for Packet<&'a T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
// Cannot use Repr::parse because we don't have the IP addresses.
try!(write!(f, "TCP src={} dst={}",
self.src_port(), self.dst_port()));
if self.syn() { try!(write!(f, " syn")) }
if self.fin() { try!(write!(f, " fin")) }
if self.rst() { try!(write!(f, " rst")) }
if self.psh() { try!(write!(f, " psh")) }
if self.ece() { try!(write!(f, " ece")) }
if self.cwr() { try!(write!(f, " cwr")) }
if self.ns() { try!(write!(f, " ns" )) }
try!(write!(f, " seq={}", self.seq_number() as u32));
2016-12-20 21:16:29 +08:00
if self.ack() {
try!(write!(f, " ack={}", self.ack_number() as u32));
2016-12-20 21:16:29 +08:00
}
try!(write!(f, " win={}", self.window_len()));
if self.urg() {
try!(write!(f, " urg={}", self.urgent_at()))
}
try!(write!(f, " len={}", self.payload().len()));
Ok(())
}
}
impl<'a> fmt::Display for Repr<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
try!(write!(f, "TCP src={} dst={} ",
self.src_port, self.dst_port));
match self.control {
Control::Syn => try!(write!(f, " syn")),
Control::Fin => try!(write!(f, " fin")),
Control::Rst => try!(write!(f, " rst")),
Control::None => ()
}
try!(write!(f, " seq={}", self.seq_number as u32));
2016-12-20 21:16:29 +08:00
if let Some(ack_number) = self.ack_number {
try!(write!(f, " ack={}", ack_number as u32));
2016-12-20 21:16:29 +08:00
}
try!(write!(f, " win={}", self.window_len));
try!(write!(f, " len={}", self.payload.len()));
Ok(())
}
}
use super::pretty_print::{PrettyPrint, PrettyIndent};
impl<T: AsRef<[u8]>> PrettyPrint for Packet<T> {
fn pretty_print(buffer: &AsRef<[u8]>, f: &mut fmt::Formatter,
indent: &mut PrettyIndent) -> fmt::Result {
match Packet::new(buffer) {
Err(err) => write!(f, "{}({})\n", indent, err),
Ok(packet) => write!(f, "{}{}\n", indent, packet)
}
}
}
2016-12-19 05:42:44 +08:00
#[cfg(test)]
mod test {
use wire::Ipv4Address;
use super::*;
const SRC_ADDR: Ipv4Address = Ipv4Address([192, 168, 1, 1]);
const DST_ADDR: Ipv4Address = Ipv4Address([192, 168, 1, 2]);
static PACKET_BYTES: [u8; 24] =
[0xbf, 0x00, 0x00, 0x50,
0x01, 0x23, 0x45, 0x67,
0x89, 0xab, 0xcd, 0xef,
0x50, 0x35, 0x01, 0x23,
0x20, 0xbe, 0x02, 0x01,
0xaa, 0x00, 0x00, 0xff];
static PAYLOAD_BYTES: [u8; 4] =
[0xaa, 0x00, 0x00, 0xff];
#[test]
fn test_deconstruct() {
let packet = Packet::new(&PACKET_BYTES[..]).unwrap();
assert_eq!(packet.src_port(), 48896);
assert_eq!(packet.dst_port(), 80);
assert_eq!(packet.seq_number(), 0x01234567);
assert_eq!(packet.ack_number(), 0x89abcdefu32 as i32);
2016-12-19 05:42:44 +08:00
assert_eq!(packet.header_len(), 20);
assert_eq!(packet.fin(), true);
assert_eq!(packet.syn(), false);
assert_eq!(packet.rst(), true);
assert_eq!(packet.psh(), false);
assert_eq!(packet.ack(), true);
assert_eq!(packet.urg(), true);
assert_eq!(packet.window_len(), 0x0123);
assert_eq!(packet.urgent_at(), 0x0201);
assert_eq!(packet.checksum(), 0x20be);
assert_eq!(packet.payload(), &PAYLOAD_BYTES[..]);
assert_eq!(packet.verify_checksum(&SRC_ADDR.into(), &DST_ADDR.into()), true);
}
#[test]
fn test_construct() {
let mut bytes = vec![0; 24];
let mut packet = Packet::new(&mut bytes).unwrap();
packet.set_src_port(48896);
packet.set_dst_port(80);
packet.set_seq_number(0x01234567);
packet.set_ack_number(0x89abcdefu32 as i32);
2016-12-19 05:42:44 +08:00
packet.set_header_len(20);
packet.set_fin(true);
packet.set_syn(false);
packet.set_rst(true);
packet.set_psh(false);
packet.set_ack(true);
packet.set_urg(true);
packet.set_window_len(0x0123);
packet.set_urgent_at(0x0201);
packet.set_checksum(0xEEEE);
packet.payload_mut().copy_from_slice(&PAYLOAD_BYTES[..]);
packet.fill_checksum(&SRC_ADDR.into(), &DST_ADDR.into());
assert_eq!(&packet.into_inner()[..], &PACKET_BYTES[..]);
}
static SYN_PACKET_BYTES: [u8; 24] =
[0xbf, 0x00, 0x00, 0x50,
0x01, 0x23, 0x45, 0x67,
0x00, 0x00, 0x00, 0x00,
0x50, 0x02, 0x01, 0x23,
0x7a, 0x8d, 0x00, 0x00,
0xaa, 0x00, 0x00, 0xff];
fn packet_repr() -> Repr<'static> {
Repr {
src_port: 48896,
dst_port: 80,
seq_number: 0x01234567,
ack_number: None,
window_len: 0x0123,
control: Control::Syn,
payload: &PAYLOAD_BYTES
}
}
#[test]
fn test_parse() {
let packet = Packet::new(&SYN_PACKET_BYTES[..]).unwrap();
let repr = Repr::parse(&packet, &SRC_ADDR.into(), &DST_ADDR.into()).unwrap();
assert_eq!(repr, packet_repr());
}
#[test]
fn test_emit() {
let repr = packet_repr();
let mut bytes = vec![0; repr.buffer_len()];
let mut packet = Packet::new(&mut bytes).unwrap();
repr.emit(&mut packet, &SRC_ADDR.into(), &DST_ADDR.into());
assert_eq!(&packet.into_inner()[..], &SYN_PACKET_BYTES[..]);
}
2016-12-19 05:42:44 +08:00
}