Implement TCP packet support.

2016-12-18 21:42:44 +00:00 · 2016-12-18 21:42:44 +00:00 · 9c922d0306
parent 71fc81b7c5
commit 9c922d0306
3 changed files with 444 additions and 1 deletions
--- a/src/wire/mod.rs
+++ b/src/wire/mod.rs
@ -86,6 +86,7 @@ mod ip;
 mod ipv4;
 mod icmpv4;
 mod udp;
+mod tcp;

 pub use self::pretty_print::PrettyPrinter;

@ -116,3 +117,5 @@ pub use self::icmpv4::Repr as Icmpv4Repr;

 pub use self::udp::Packet as UdpPacket;
 pub use self::udp::Repr as UdpRepr;
+
+pub use self::tcp::Packet as TcpPacket;
--- a/src/wire/tcp.rs
+++ b/src/wire/tcp.rs
@ -0,0 +1,440 @@
+use byteorder::{ByteOrder, NetworkEndian};
+
+use Error;
+use super::{InternetProtocolType, InternetAddress};
+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) -> u32 {
+        let data = self.buffer.as_ref();
+        NetworkEndian::read_u32(&data[field::SEQ_NUM])
+    }
+
+    /// Return the acknowledgement number field.
+    #[inline(always)]
+    pub fn ack_number(&self) -> u32 {
+        let data = self.buffer.as_ref();
+        NetworkEndian::read_u32(&data[field::ACK_NUM])
+    }
+
+    /// 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: &InternetAddress, dst_addr: &InternetAddress) -> bool {
+        let data = self.buffer.as_ref();
+        checksum::combine(&[
+            checksum::pseudo_header(src_addr, dst_addr, InternetProtocolType::Tcp,
+                                    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: u32) {
+        let mut data = self.buffer.as_mut();
+        NetworkEndian::write_u32(&mut data[field::SEQ_NUM], value)
+    }
+
+    /// Set the acknowledgement number field.
+    #[inline(always)]
+    pub fn set_ack_number(&mut self, value: u32) {
+        let mut data = self.buffer.as_mut();
+        NetworkEndian::write_u32(&mut data[field::ACK_NUM], value)
+    }
+
+    /// 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: &InternetAddress, dst_addr: &InternetAddress) {
+        self.set_checksum(0);
+        let checksum = {
+            let data = self.buffer.as_ref();
+            !checksum::combine(&[
+                checksum::pseudo_header(src_addr, dst_addr, InternetProtocolType::Tcp,
+                                        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..]
+    }
+}
+
+#[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(), 0x89abcdef);
+        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(0x89abcdef);
+        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[..]);
+    }
+}
--- a/src/wire/udp.rs
+++ b/src/wire/udp.rs
@ -150,7 +150,7 @@ impl<T: AsRef<[u8]> + AsMut<[u8]>> Packet<T> {
 }

 impl<'a, T: AsRef<[u8]> + AsMut<[u8]> + ?Sized> Packet<&'a mut T> {
-    /// Return a mutable pointer to the type-specific data.
+    /// Return a mutable pointer to the payload.
    #[inline(always)]
    pub fn payload_mut(&mut self) -> &mut [u8] {
        let length = self.len();