333 lines
11 KiB
Rust
333 lines
11 KiB
Rust
use core::fmt;
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use crate::{Error, Result};
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use crate::wire::ipv6option::Ipv6OptionsIterator;
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pub use super::IpProtocol as Protocol;
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/// A read/write wrapper around an IPv6 Hop-by-Hop Options Header.
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#[derive(Debug, PartialEq)]
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pub struct Header<T: AsRef<[u8]>> {
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buffer: T
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}
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// Format of the Hop-by-Hop Options Header
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//
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Next Header | Hdr Ext Len | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
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// | |
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// . .
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// . Options .
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// . .
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// | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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//
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//
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// See https://tools.ietf.org/html/rfc8200#section-4.3 for details.
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mod field {
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#![allow(non_snake_case)]
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use crate::wire::field::*;
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// Minimum size of the header.
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pub const MIN_HEADER_SIZE: usize = 8;
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// 8-bit identifier of the header immediately following this header.
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pub const NXT_HDR: usize = 0;
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// 8-bit unsigned integer. Length of the OPTIONS field in 8-octet units,
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// not including the first 8 octets.
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pub const LENGTH: usize = 1;
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// Variable-length field. Option-Type-specific data.
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//
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// Length of the header is in 8-octet units, not including the first 8 octets. The first two
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// octets are the next header type and the header length.
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pub fn OPTIONS(length_field: u8) -> Field {
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let bytes = length_field * 8 + 8;
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2..bytes as usize
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}
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}
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impl<T: AsRef<[u8]>> Header<T> {
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/// Create a raw octet buffer with an IPv6 Hop-by-Hop Options Header structure.
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pub fn new_unchecked(buffer: T) -> Header<T> {
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Header { buffer }
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}
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/// Shorthand for a combination of [new_unchecked] and [check_len].
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///
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/// [new_unchecked]: #method.new_unchecked
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/// [check_len]: #method.check_len
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pub fn new_checked(buffer: T) -> Result<Header<T>> {
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let header = Self::new_unchecked(buffer);
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header.check_len()?;
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Ok(header)
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}
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/// Ensure that no accessor method will panic if called.
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/// Returns `Err(Error::Truncated)` if the buffer is too short.
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///
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/// The result of this check is invalidated by calling [set_header_len].
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///
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/// [set_header_len]: #method.set_header_len
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pub fn check_len(&self) -> Result<()> {
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let data = self.buffer.as_ref();
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let len = data.len();
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if len < field::MIN_HEADER_SIZE {
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return Err(Error::Truncated);
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}
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let of = field::OPTIONS(data[field::LENGTH]);
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if len < of.end {
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return Err(Error::Truncated);
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}
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Ok(())
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}
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/// Consume the header, returning the underlying buffer.
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pub fn into_inner(self) -> T {
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self.buffer
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}
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/// Return the next header field.
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#[inline]
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pub fn next_header(&self) -> Protocol {
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let data = self.buffer.as_ref();
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Protocol::from(data[field::NXT_HDR])
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}
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/// Return length of the Hop-by-Hop Options header in 8-octet units, not including the first
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/// 8 octets.
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#[inline]
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pub fn header_len(&self) -> u8 {
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let data = self.buffer.as_ref();
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data[field::LENGTH]
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}
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}
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impl<'a, T: AsRef<[u8]> + ?Sized> Header<&'a T> {
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/// Return the option data.
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#[inline]
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pub fn options(&self) -> &'a[u8] {
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let data = self.buffer.as_ref();
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&data[field::OPTIONS(data[field::LENGTH])]
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}
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}
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impl<T: AsRef<[u8]> + AsMut<[u8]>> Header<T> {
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/// Set the next header field.
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#[inline]
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pub fn set_next_header(&mut self, value: Protocol) {
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let data = self.buffer.as_mut();
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data[field::NXT_HDR] = value.into();
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}
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/// Set the option data length. Length of the Hop-by-Hop Options header in 8-octet units,
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/// not including the first 8 octets.
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#[inline]
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pub fn set_header_len(&mut self, value: u8) {
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let data = self.buffer.as_mut();
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data[field::LENGTH] = value;
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}
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}
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impl<'a, T: AsRef<[u8]> + AsMut<[u8]> + ?Sized> Header<&'a mut T> {
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/// Return a mutable pointer to the option data.
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#[inline]
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pub fn options_mut(&mut self) -> &mut [u8] {
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let data = self.buffer.as_mut();
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let len = data[field::LENGTH];
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&mut data[field::OPTIONS(len)]
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}
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}
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impl<'a, T: AsRef<[u8]> + ?Sized> fmt::Display for Header<&'a T> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match Repr::parse(self) {
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Ok(repr) => write!(f, "{}", repr),
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Err(err) => {
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write!(f, "IPv6 Hop-by-Hop Options ({})", err)?;
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Ok(())
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}
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}
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}
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}
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/// A high-level representation of an IPv6 Hop-by-Hop Options header.
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#[derive(Debug, PartialEq, Eq, Clone, Copy)]
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pub struct Repr<'a> {
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/// The type of header immediately following the Hop-by-Hop Options header.
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pub next_header: Protocol,
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/// Length of the Hop-by-Hop Options header in 8-octet units, not including the first 8 octets.
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pub length: u8,
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/// The options contained in the Hop-by-Hop Options header.
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pub options: &'a [u8]
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}
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impl<'a> Repr<'a> {
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/// Parse an IPv6 Hop-by-Hop Options Header and return a high-level representation.
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pub fn parse<T>(header: &Header<&'a T>) -> Result<Repr<'a>> where T: AsRef<[u8]> + ?Sized {
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Ok(Repr {
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next_header: header.next_header(),
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length: header.header_len(),
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options: header.options()
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})
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}
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/// Return the length, in bytes, of a header that will be emitted from this high-level
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/// representation.
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pub fn buffer_len(&self) -> usize {
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field::OPTIONS(self.length).end
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}
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/// Emit a high-level representation into an IPv6 Hop-by-Hop Options Header.
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pub fn emit<T: AsRef<[u8]> + AsMut<[u8]> + ?Sized>(&self, header: &mut Header<&mut T>) {
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header.set_next_header(self.next_header);
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header.set_header_len(self.length);
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header.options_mut().copy_from_slice(self.options);
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}
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/// Return an `Iterator` for the contained options.
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pub fn options(&self) -> Ipv6OptionsIterator {
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Ipv6OptionsIterator::new(self.options, self.buffer_len() - 2)
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}
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}
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impl<'a> fmt::Display for Repr<'a> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "IPv6 Hop-by-Hop Options next_hdr={} length={} ", self.next_header, self.length)
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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// A Hop-by-Hop Option header with a PadN option of option data length 4.
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static REPR_PACKET_PAD4: [u8; 8] = [0x6, 0x0, 0x1, 0x4,
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0x0, 0x0, 0x0, 0x0];
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// A Hop-by-Hop Option header with a PadN option of option data length 12.
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static REPR_PACKET_PAD12: [u8; 16] = [0x06, 0x1, 0x1, 0x12,
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0x0, 0x0, 0x0, 0x0,
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0x0, 0x0, 0x0, 0x0,
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0x0, 0x0, 0x0, 0x0];
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#[test]
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fn test_check_len() {
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// zero byte buffer
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assert_eq!(Err(Error::Truncated),
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Header::new_unchecked(&REPR_PACKET_PAD4[..0]).check_len());
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// no length field
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assert_eq!(Err(Error::Truncated),
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Header::new_unchecked(&REPR_PACKET_PAD4[..1]).check_len());
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// less than 8 bytes
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assert_eq!(Err(Error::Truncated),
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Header::new_unchecked(&REPR_PACKET_PAD4[..7]).check_len());
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// valid
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assert_eq!(Ok(()),
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Header::new_unchecked(&REPR_PACKET_PAD4).check_len());
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// valid
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assert_eq!(Ok(()),
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Header::new_unchecked(&REPR_PACKET_PAD12).check_len());
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// length field value greater than number of bytes
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let header: [u8; 8] = [0x06, 0x2, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0];
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assert_eq!(Err(Error::Truncated),
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Header::new_unchecked(&header).check_len());
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}
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#[test]
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fn test_header_deconstruct() {
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let header = Header::new_unchecked(&REPR_PACKET_PAD4);
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assert_eq!(header.next_header(), Protocol::Tcp);
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assert_eq!(header.header_len(), 0);
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assert_eq!(header.options(), &REPR_PACKET_PAD4[2..]);
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let header = Header::new_unchecked(&REPR_PACKET_PAD12);
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assert_eq!(header.next_header(), Protocol::Tcp);
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assert_eq!(header.header_len(), 1);
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assert_eq!(header.options(), &REPR_PACKET_PAD12[2..]);
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}
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#[test]
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fn test_overlong() {
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let mut bytes = vec![];
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bytes.extend(&REPR_PACKET_PAD4[..]);
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bytes.push(0);
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assert_eq!(Header::new_unchecked(&bytes).options().len(),
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REPR_PACKET_PAD4[2..].len());
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assert_eq!(Header::new_unchecked(&mut bytes).options_mut().len(),
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REPR_PACKET_PAD4[2..].len());
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let mut bytes = vec![];
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bytes.extend(&REPR_PACKET_PAD12[..]);
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bytes.push(0);
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assert_eq!(Header::new_unchecked(&bytes).options().len(),
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REPR_PACKET_PAD12[2..].len());
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assert_eq!(Header::new_unchecked(&mut bytes).options_mut().len(),
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REPR_PACKET_PAD12[2..].len());
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}
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#[test]
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fn test_header_len_overflow() {
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let mut bytes = vec![];
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bytes.extend(&REPR_PACKET_PAD4);
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let len = bytes.len() as u8;
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Header::new_unchecked(&mut bytes).set_header_len(len + 1);
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assert_eq!(Header::new_checked(&bytes).unwrap_err(), Error::Truncated);
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let mut bytes = vec![];
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bytes.extend(&REPR_PACKET_PAD12);
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let len = bytes.len() as u8;
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Header::new_unchecked(&mut bytes).set_header_len(len + 1);
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assert_eq!(Header::new_checked(&bytes).unwrap_err(), Error::Truncated);
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}
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#[test]
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fn test_repr_parse_valid() {
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let header = Header::new_unchecked(&REPR_PACKET_PAD4);
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let repr = Repr::parse(&header).unwrap();
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assert_eq!(repr, Repr {
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next_header: Protocol::Tcp, length: 0, options: &REPR_PACKET_PAD4[2..]
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});
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let header = Header::new_unchecked(&REPR_PACKET_PAD12);
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let repr = Repr::parse(&header).unwrap();
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assert_eq!(repr, Repr {
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next_header: Protocol::Tcp, length: 1, options: &REPR_PACKET_PAD12[2..]
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});
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}
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#[test]
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fn test_repr_emit() {
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let repr = Repr{ next_header: Protocol::Tcp, length: 0, options: &REPR_PACKET_PAD4[2..] };
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let mut bytes = [0u8; 8];
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let mut header = Header::new_unchecked(&mut bytes);
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repr.emit(&mut header);
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assert_eq!(header.into_inner(), &REPR_PACKET_PAD4[..]);
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let repr = Repr{ next_header: Protocol::Tcp, length: 1, options: &REPR_PACKET_PAD12[2..] };
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let mut bytes = [0u8; 16];
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let mut header = Header::new_unchecked(&mut bytes);
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repr.emit(&mut header);
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assert_eq!(header.into_inner(), &REPR_PACKET_PAD12[..]);
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}
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#[test]
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fn test_buffer_len() {
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let header = Header::new_unchecked(&REPR_PACKET_PAD4);
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let repr = Repr::parse(&header).unwrap();
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assert_eq!(repr.buffer_len(), REPR_PACKET_PAD4.len());
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let header = Header::new_unchecked(&REPR_PACKET_PAD12);
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let repr = Repr::parse(&header).unwrap();
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assert_eq!(repr.buffer_len(), REPR_PACKET_PAD12.len());
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}
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}
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