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use crate::*;
use core::slice::from_raw_parts;
///A slice containing a single vlan header of a network package.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SingleVlanHeaderSlice<'a> {
slice: &'a [u8],
}
impl<'a> SingleVlanHeaderSlice<'a> {
///Creates a vlan header slice from a slice.
#[inline]
pub fn from_slice(slice: &'a [u8]) -> Result<SingleVlanHeaderSlice<'a>, err::LenError> {
//check length
if slice.len() < SingleVlanHeader::LEN {
return Err(err::LenError {
required_len: SingleVlanHeader::LEN,
len: slice.len(),
len_source: LenSource::Slice,
layer: err::Layer::VlanHeader,
layer_start_offset: 0,
});
}
//all done
Ok(SingleVlanHeaderSlice::<'a> {
// SAFETY:
// Safe as the slice length is checked beforehand to have
// at least the length of SingleVlanHeader::LEN (4)
slice: unsafe { from_raw_parts(slice.as_ptr(), SingleVlanHeader::LEN) },
})
}
/// Converts the given slice into a vlan header slice WITHOUT any
/// checks to ensure that the data present is an vlan header or that the
/// slice length is matching the header length.
///
/// If you are not sure what this means, use [`SingleVlanHeaderSlice::from_slice`]
/// instead.
///
/// # Safety
///
/// The caller must ensured that the given slice has the length of
/// [`SingleVlanHeader::LEN`]
#[inline]
pub(crate) unsafe fn from_slice_unchecked(slice: &[u8]) -> SingleVlanHeaderSlice {
SingleVlanHeaderSlice { slice }
}
/// Returns the slice containing the single vlan header
#[inline]
pub fn slice(&self) -> &'a [u8] {
self.slice
}
/// Read the "priority_code_point" field from the slice. This is a 3 bit number which refers to the IEEE 802.1p class of service and maps to the frame priority level.
#[inline]
pub fn priority_code_point(&self) -> VlanPcp {
unsafe {
// SAFETY: Safe as slice len checked in constructor to be at least 4 &
// the bitmask guarantees values does not exceed 0b0000_0111.
VlanPcp::new_unchecked((*self.slice.get_unchecked(0) >> 5) & 0b0000_0111)
}
}
/// Read the "drop_eligible_indicator" flag from the slice. Indicates that the frame may be dropped under the presence of congestion.
#[inline]
pub fn drop_eligible_indicator(&self) -> bool {
// SAFETY:
// Slice len checked in constructor to be at least 4.
unsafe { 0 != (*self.slice.get_unchecked(0) & 0x10) }
}
/// Reads the 12 bits "vland identifier" field from the slice.
#[inline]
pub fn vlan_identifier(&self) -> VlanId {
// SAFETY:
// Slice len checked in constructor to be at least 4 &
// value and the value is guaranteed not to exceed
// 0b0000_1111_1111_1111 as the upper bits have been
// bitmasked out.
unsafe {
VlanId::new_unchecked(u16::from_be_bytes([
*self.slice.get_unchecked(0) & 0b0000_1111,
*self.slice.get_unchecked(1),
]))
}
}
/// Read the "Tag protocol identifier" field from the slice. Refer to the "EtherType" for a list of possible supported values.
#[inline]
pub fn ether_type(&self) -> EtherType {
// SAFETY:
// Slice len checked in constructor to be at least 4.
EtherType(unsafe { get_unchecked_be_u16(self.slice.as_ptr().add(2)) })
}
/// Decode all the fields and copy the results to a SingleVlanHeader struct
#[inline]
pub fn to_header(&self) -> SingleVlanHeader {
SingleVlanHeader {
pcp: self.priority_code_point(),
drop_eligible_indicator: self.drop_eligible_indicator(),
vlan_id: self.vlan_identifier(),
ether_type: self.ether_type(),
}
}
}
#[cfg(test)]
mod test {
use crate::{test_gens::*, *};
use alloc::{format, vec::Vec};
use proptest::prelude::*;
proptest! {
#[test]
fn from_slice(
input in vlan_single_any(),
dummy_data in proptest::collection::vec(any::<u8>(), 0..20)
) {
// serialize
let mut buffer: Vec<u8> = Vec::with_capacity(input.header_len() + dummy_data.len());
input.write(&mut buffer).unwrap();
buffer.extend(&dummy_data[..]);
// normal
{
let slice = SingleVlanHeaderSlice::from_slice(&buffer).unwrap();
assert_eq!(slice.slice(), &buffer[..4]);
}
// slice length to small
for len in 0..4 {
assert_eq!(
SingleVlanHeaderSlice::from_slice(&buffer[..len])
.unwrap_err(),
err::LenError{
required_len: 4,
len: len,
len_source: LenSource::Slice,
layer: err::Layer::VlanHeader,
layer_start_offset: 0,
}
);
}
}
}
proptest! {
#[test]
fn getters(input in vlan_single_any()) {
let bytes = input.to_bytes();
let slice = SingleVlanHeaderSlice::from_slice(&bytes).unwrap();
assert_eq!(input.pcp, slice.priority_code_point());
assert_eq!(input.drop_eligible_indicator, slice.drop_eligible_indicator());
assert_eq!(input.vlan_id, slice.vlan_identifier());
assert_eq!(input.ether_type, slice.ether_type());
}
}
proptest! {
#[test]
fn to_header(input in vlan_single_any()) {
let bytes = input.to_bytes();
let slice = SingleVlanHeaderSlice::from_slice(&bytes).unwrap();
assert_eq!(input, slice.to_header());
}
}
proptest! {
#[test]
fn clone_eq(input in vlan_single_any()) {
let bytes = input.to_bytes();
let slice = SingleVlanHeaderSlice::from_slice(&bytes).unwrap();
assert_eq!(slice, slice.clone());
}
}
proptest! {
#[test]
fn dbg(input in vlan_single_any()) {
let bytes = input.to_bytes();
let slice = SingleVlanHeaderSlice::from_slice(&bytes).unwrap();
assert_eq!(
&format!(
"SingleVlanHeaderSlice {{ slice: {:?} }}",
slice.slice(),
),
&format!("{:?}", slice)
);
}
}
}