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use anyhow::Context;
use std::net::IpAddr;
use crate::{
constants,
nlas::{NlaBuffer, NlasIterator},
parsers::parse_ip,
route::nlas::Nla,
traits::{Emitable, Parseable},
DecodeError,
};
bitflags! {
#[non_exhaustive]
pub struct NextHopFlags: u8 {
const RTNH_F_EMPTY = 0;
const RTNH_F_DEAD = constants::RTNH_F_DEAD;
const RTNH_F_PERVASIVE = constants::RTNH_F_PERVASIVE;
const RTNH_F_ONLINK = constants::RTNH_F_ONLINK;
const RTNH_F_OFFLOAD = constants::RTNH_F_OFFLOAD;
const RTNH_F_LINKDOWN = constants::RTNH_F_LINKDOWN;
const RTNH_F_UNRESOLVED = constants::RTNH_F_UNRESOLVED;
}
}
const PAYLOAD_OFFSET: usize = 8;
buffer!(NextHopBuffer {
length: (u16, 0..2),
flags: (u8, 2),
hops: (u8, 3),
interface_id: (u32, 4..8),
payload: (slice, PAYLOAD_OFFSET..),
});
impl<T: AsRef<[u8]>> NextHopBuffer<T> {
pub fn new_checked(buffer: T) -> Result<Self, DecodeError> {
let packet = Self::new(buffer);
packet.check_buffer_length()?;
Ok(packet)
}
fn check_buffer_length(&self) -> Result<(), DecodeError> {
let len = self.buffer.as_ref().len();
if len < PAYLOAD_OFFSET {
return Err(format!(
"invalid NextHopBuffer: length {len} < {PAYLOAD_OFFSET}"
)
.into());
}
if len < self.length() as usize {
return Err(format!(
"invalid NextHopBuffer: length {} < {}",
len,
8 + self.length()
)
.into());
}
Ok(())
}
}
impl<'a, T: AsRef<[u8]> + ?Sized> NextHopBuffer<&'a T> {
pub fn nlas(
&self,
) -> impl Iterator<Item = Result<NlaBuffer<&'a [u8]>, DecodeError>> {
NlasIterator::new(
&self.payload()[..(self.length() as usize - PAYLOAD_OFFSET)],
)
}
}
#[derive(Debug, Clone, Eq, PartialEq)]
#[non_exhaustive]
pub struct NextHop {
pub flags: NextHopFlags,
pub hops: u8,
pub interface_id: u32,
pub nlas: Vec<Nla>,
}
impl<'a, T: AsRef<[u8]>> Parseable<NextHopBuffer<&'a T>> for NextHop {
fn parse(buf: &NextHopBuffer<&T>) -> Result<NextHop, DecodeError> {
let nlas = Vec::<Nla>::parse(
&NextHopBuffer::new_checked(buf.buffer)
.context("cannot parse route attributes in next-hop")?,
)
.context("cannot parse route attributes in next-hop")?;
Ok(NextHop {
flags: NextHopFlags::from_bits_truncate(buf.flags()),
hops: buf.hops(),
interface_id: buf.interface_id(),
nlas,
})
}
}
impl<'a, T: AsRef<[u8]> + 'a> Parseable<NextHopBuffer<&'a T>> for Vec<Nla> {
fn parse(buf: &NextHopBuffer<&'a T>) -> Result<Self, DecodeError> {
let mut nlas = vec![];
for nla_buf in buf.nlas() {
nlas.push(Nla::parse(&nla_buf?)?);
}
Ok(nlas)
}
}
impl Emitable for NextHop {
fn buffer_len(&self) -> usize {
PAYLOAD_OFFSET + self.nlas.as_slice().buffer_len()
}
fn emit(&self, buffer: &mut [u8]) {
let mut nh_buffer = NextHopBuffer::new(buffer);
nh_buffer.set_length(self.buffer_len() as u16);
nh_buffer.set_flags(self.flags.bits());
nh_buffer.set_hops(self.hops);
nh_buffer.set_interface_id(self.interface_id);
self.nlas.as_slice().emit(nh_buffer.payload_mut())
}
}
impl NextHop {
pub fn gateway(&self) -> Option<IpAddr> {
self.nlas.iter().find_map(|nla| {
if let Nla::Gateway(ip) = nla {
parse_ip(ip).ok()
} else {
None
}
})
}
}