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use crate::{err::*, *};
/// Slice containing a VLAN header & payload.
#[derive(Clone, Eq, PartialEq)]
pub struct SingleVlanSlice<'a> {
pub(crate) slice: &'a [u8],
}
impl<'a> SingleVlanSlice<'a> {
/// Try creating a [`SingleVlanSlice`] from a slice containing the
/// VLAN header & payload.
pub fn from_slice(slice: &'a [u8]) -> Result<SingleVlanSlice<'a>, 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,
});
}
Ok(SingleVlanSlice { slice })
}
/// Returns the slice containing the VLAN header and payload.
#[inline]
pub fn slice(&self) -> &'a [u8] {
self.slice
}
/// Read the "priority_code_point" field of the VLAN header.
///
/// 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 bit mask guarantees values does not exceed 0b0000_0111.
VlanPcp::new_unchecked((*self.slice.get_unchecked(0) >> 5) & 0b0000_0111)
}
}
/// Read the "drop_eligible_indicator" flag of the VLAN header.
///
/// 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 "vlan identifier" field from the VLAN header.
#[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
// bit-masked 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 VLAN header.
///
/// 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(),
}
}
/// Slice containing the Ethernet 2 header.
pub fn header_slice(&self) -> &[u8] {
unsafe {
// SAFETY:
// Safe as the constructor checks that the slice has
// at least the length of SingleVlanHeader::LEN (4).
core::slice::from_raw_parts(self.slice.as_ptr(), SingleVlanHeader::LEN)
}
}
/// Returns the slice containing the VLAN payload & ether type
/// identifying it's content type.
#[inline]
pub fn payload(&self) -> EtherPayloadSlice<'a> {
EtherPayloadSlice {
ether_type: self.ether_type(),
len_source: LenSource::Slice,
payload: self.payload_slice(),
}
}
/// Returns the slice containing the VLAN payload.
#[inline]
pub fn payload_slice(&self) -> &'a [u8] {
unsafe {
// SAFETY:
// Safe as the constructor checks that the slice has
// at least the length of SingleVlanHeader::LEN (4).
core::slice::from_raw_parts(
self.slice.as_ptr().add(SingleVlanHeader::LEN),
self.slice.len() - SingleVlanHeader::LEN,
)
}
}
/// Length of the VLAN header in bytes (equal to
/// [`crate::SingleVlanHeader::LEN`]).
#[inline]
pub const fn header_len(&self) -> usize {
SingleVlanHeader::LEN
}
}
impl core::fmt::Debug for SingleVlanSlice<'_> {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
f.debug_struct("SingleVlanSlice")
.field("header", &self.to_header())
.field("payload", &self.payload())
.finish()
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::test_gens::*;
use alloc::{format, vec::Vec};
use proptest::prelude::*;
proptest! {
#[test]
fn debug_clone_eq(
vlan in vlan_single_any()
) {
let payload: [u8;8] = [1,2,3,4,5,6,7,8];
let mut data = Vec::with_capacity(
vlan.header_len() +
payload.len()
);
data.extend_from_slice(&vlan.to_bytes());
data.extend_from_slice(&payload);
// decode packet
let slice = SingleVlanSlice::from_slice(&data).unwrap();
// check debug output
prop_assert_eq!(
format!("{:?}", slice),
format!(
"SingleVlanSlice {{ header: {:?}, payload: {:?} }}",
slice.to_header(),
slice.payload(),
)
);
prop_assert_eq!(slice.clone(), slice);
}
}
proptest! {
#[test]
fn getters(vlan in vlan_single_any()) {
let payload: [u8;8] = [1,2,3,4,5,6,7,8];
let mut data = Vec::with_capacity(
vlan.header_len() +
payload.len()
);
data.extend_from_slice(&vlan.to_bytes());
data.extend_from_slice(&payload);
let slice = SingleVlanSlice::from_slice(&data).unwrap();
assert_eq!(&data, slice.slice());
assert_eq!(vlan.pcp, slice.priority_code_point());
assert_eq!(vlan.drop_eligible_indicator, slice.drop_eligible_indicator());
assert_eq!(vlan.vlan_id, slice.vlan_identifier());
assert_eq!(vlan.ether_type, slice.ether_type());
assert_eq!(vlan, slice.to_header());
assert_eq!(&data[..SingleVlanHeader::LEN], slice.header_slice());
assert_eq!(
EtherPayloadSlice {
ether_type: vlan.ether_type,
len_source: LenSource::Slice,
payload: &data[SingleVlanHeader::LEN..],
},
slice.payload()
);
assert_eq!(&data[SingleVlanHeader::LEN..], slice.payload_slice());
assert_eq!(SingleVlanHeader::LEN, slice.header_len());
}
}
proptest! {
#[test]
fn from_slice(vlan in vlan_single_any()) {
let payload: [u8;10] = [1,2,3,4,5,6,7,8,9,10];
let data = {
let mut data = Vec::with_capacity(
vlan.header_len() +
payload.len()
);
data.extend_from_slice(&vlan.to_bytes());
data.extend_from_slice(&payload);
data
};
// normal decode
{
let slice = SingleVlanSlice::from_slice(&data).unwrap();
assert_eq!(slice.to_header(), vlan);
assert_eq!(slice.payload_slice(), &payload);
}
// length error
for len in 0..SingleVlanHeader::LEN {
assert_eq!(
SingleVlanSlice::from_slice(&data[..len]).unwrap_err(),
LenError{
required_len: SingleVlanHeader::LEN,
len,
len_source: LenSource::Slice,
layer: Layer::VlanHeader,
layer_start_offset: 0
}
);
}
}
}
}