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use byteorder::{BigEndian, ReadBytesExt};
use std::convert::TryFrom;
use std::io::{Cursor, Error, ErrorKind, Read};
use crate::*;
/// Used when announcing routes to non-IPv4 addresses.
#[derive(Debug, Clone)]
pub struct MPReachNLRI {
/// The Address Family Identifier of the routes being announced.
pub afi: AFI,
/// The Subsequent Address Family Identifier of the routes being announced.
pub safi: SAFI,
/// The next hop of the announced routes.
pub next_hop: Vec<u8>,
/// The routes that are being announced.
pub announced_routes: Vec<NLRIEncoding>,
}
impl MPReachNLRI {
/// Parse MPUnreachNLRI information
pub(crate) fn parse(
stream: &mut impl Read,
length: u16,
capabilities: &Capabilities,
) -> Result<MPReachNLRI, Error> {
let afi = AFI::try_from(stream.read_u16::<BigEndian>()?)?;
let safi = SAFI::try_from(stream.read_u8()?)?;
let next_hop_length = stream.read_u8()?;
let mut next_hop = vec![0; usize::from(next_hop_length)];
stream.read_exact(&mut next_hop)?;
let _reserved = stream.read_u8()?;
// ----------------------------
// Read NLRI
// ----------------------------
let size = length - u16::from(5 + next_hop_length);
let mut buffer = vec![0; usize::from(size)];
stream.read_exact(&mut buffer)?;
let mut cursor = Cursor::new(buffer);
let mut announced_routes: Vec<NLRIEncoding> = Vec::with_capacity(4);
match afi {
AFI::IPV4 | AFI::IPV6 => {
while cursor.position() < u64::from(size) {
match safi {
// Labelled nexthop
// TODO Add label parsing and support capabilities.MULTIPLE_LABELS
SAFI::Mpls => {
let path_id = if util::detect_add_path_prefix(&mut cursor, 255)? {
Some(cursor.read_u32::<BigEndian>()?)
} else {
None
};
let len_bits = cursor.read_u8()?;
// Protect against malformed messages
if len_bits == 0 {
return Err(Error::new(
ErrorKind::Other,
"Invalid prefix length 0",
));
}
let len_bytes = (f32::from(len_bits) / 8.0).ceil() as u8;
// discard label, resv and s-bit for now
cursor.read_exact(&mut [0u8; 3])?;
let remaining = (len_bytes - 3) as usize;
let mut pfx_buf = afi.empty_buffer();
cursor.read_exact(&mut pfx_buf[..remaining])?;
// len_bits - MPLS info
let pfx_len = len_bits - 24;
let prefix = Prefix::new(afi, pfx_len, pfx_buf);
match path_id {
Some(path_id) => announced_routes.push(
NLRIEncoding::IP_MPLS_WITH_PATH_ID((prefix, 0u32, path_id)),
),
None => {
announced_routes.push(NLRIEncoding::IP_MPLS((prefix, 0u32)))
}
};
}
SAFI::MplsVpn => {
let len_bits = cursor.read_u8()?;
let len_bytes = (f32::from(len_bits) / 8.0).ceil() as u8;
// discard label, resv and s-bit for now
cursor.read_exact(&mut [0u8; 3])?;
let remaining = (len_bytes - 3) as usize;
let rd = cursor.read_u64::<BigEndian>()?;
let mut pfx_buf = afi.empty_buffer();
cursor.read_exact(&mut pfx_buf[..(remaining - 8)])?;
// len_bits - MPLS info - Route Distinguisher
let pfx_len = len_bits - 24 - 64;
let prefix = Prefix::new(afi, pfx_len, pfx_buf);
announced_routes.push(NLRIEncoding::IP_VPN_MPLS((rd, prefix, 0u32)));
}
#[cfg(feature = "flowspec")]
SAFI::Flowspec => {
let mut nlri_length = cursor.read_u8()?;
let mut filters: Vec<FlowspecFilter> = vec![];
while nlri_length > 0 {
let cur_position = cursor.position();
filters.push(FlowspecFilter::parse(&mut cursor, afi)?);
nlri_length -= (cursor.position() - cur_position) as u8;
}
announced_routes.push(NLRIEncoding::FLOWSPEC(filters));
}
#[cfg(feature = "flowspec")]
SAFI::FlowspecVPN => {
unimplemented!();
}
_ => {
if capabilities.EXTENDED_PATH_NLRI_SUPPORT {
while cursor.position() < u64::from(size) {
let path_id = cursor.read_u32::<BigEndian>()?;
let prefix = Prefix::parse(&mut cursor, afi)?;
announced_routes
.push(NLRIEncoding::IP_WITH_PATH_ID((prefix, path_id)));
}
} else {
while cursor.position() < u64::from(size) {
let prefix = Prefix::parse(&mut cursor, afi)?;
announced_routes.push(NLRIEncoding::IP(prefix));
}
}
}
};
}
}
AFI::L2VPN => {
let _len = cursor.read_u16::<BigEndian>()?;
let rd = cursor.read_u64::<BigEndian>()?;
let ve_id = cursor.read_u16::<BigEndian>()?;
let label_block_offset = cursor.read_u16::<BigEndian>()?;
let label_block_size = cursor.read_u16::<BigEndian>()?;
let label_base = cursor.read_u24::<BigEndian>()?;
announced_routes.push(NLRIEncoding::L2VPN((
rd,
ve_id,
label_block_offset,
label_block_size,
label_base,
)));
}
AFI::BGPLS => unimplemented!(),
};
Ok(MPReachNLRI {
afi,
safi,
next_hop,
announced_routes,
})
}
/// Encode Multiprotocol Reach NLRI to bytes
pub fn encode(&self, mut buf: &mut impl Write) -> Result<(), Error> {
buf.write_u16::<BigEndian>(self.afi as u16)?;
buf.write_u8(self.safi as u8)?;
buf.write_u8(self.next_hop.len() as u8)?;
buf.write_all(&self.next_hop)?;
buf.write_u8(0u8)?; // Reserved
for nlri in &self.announced_routes {
nlri.encode(&mut buf)?;
}
Ok(())
}
}
/// Used when withdrawing routes to non-IPv4 addresses.
#[derive(Debug, Clone)]
pub struct MPUnreachNLRI {
/// The Address Family Identifier of the routes being withdrawn.
pub afi: AFI,
/// The Subsequent Address Family Identifier of the routes being withdrawn.
pub safi: SAFI,
/// The routes being withdrawn.
pub withdrawn_routes: Vec<NLRIEncoding>,
}
impl MPUnreachNLRI {
/// Parse MPUnreachNLRI information
pub(crate) fn parse(
stream: &mut impl Read,
length: u16,
capabilities: &Capabilities,
) -> Result<MPUnreachNLRI, Error> {
let afi = AFI::try_from(stream.read_u16::<BigEndian>()?)?;
let safi = SAFI::try_from(stream.read_u8()?)?;
// ----------------------------
// Read NLRI
// ----------------------------
let size = length - 3;
let mut buffer = vec![0; usize::from(size)];
stream.read_exact(&mut buffer)?;
let mut cursor = Cursor::new(buffer);
let mut withdrawn_routes: Vec<NLRIEncoding> = Vec::with_capacity(4);
while cursor.position() < u64::from(size) {
match safi {
// Labelled nexthop
// TODO Add label parsing and support capabilities.MULTIPLE_LABELS
SAFI::Mpls => {
let path_id = if util::detect_add_path_prefix(&mut cursor, 255)? {
Some(cursor.read_u32::<BigEndian>()?)
} else {
None
};
let len_bits = cursor.read_u8()?;
// Protect against malformed messages
if len_bits == 0 {
return Err(Error::new(ErrorKind::Other, "Invalid prefix length 0"));
}
let len_bytes = (f32::from(len_bits) / 8.0).ceil() as u8;
// discard label, resv and s-bit for now
cursor.read_exact(&mut [0u8; 3])?;
let remaining = (len_bytes - 3) as usize;
let mut pfx_buf = afi.empty_buffer();
cursor.read_exact(&mut pfx_buf[..remaining])?;
// len_bits - MPLS info
let pfx_len = len_bits - 24;
match path_id {
Some(path_id) => withdrawn_routes.push(NLRIEncoding::IP_MPLS_WITH_PATH_ID(
(Prefix::new(afi, pfx_len, pfx_buf), 0, path_id),
)),
None => withdrawn_routes.push(NLRIEncoding::IP_MPLS((
Prefix::new(afi, pfx_len, pfx_buf),
0,
))),
};
}
SAFI::MplsVpn => {
let len_bits = cursor.read_u8()?;
let len_bytes = (f32::from(len_bits) / 8.0).ceil() as u8;
// Upon reception, the value of the Compatibility field MUST be ignored.
cursor.read_exact(&mut [0u8; 3])?;
let remaining = (len_bytes - 3) as usize;
let rd = cursor.read_u64::<BigEndian>()?;
let mut pfx_buf = afi.empty_buffer();
cursor.read_exact(&mut pfx_buf[..(remaining - 8)])?;
// len_bits - MPLS info - Route Distinguisher
let pfx_len = len_bits - 24 - 64;
withdrawn_routes.push(NLRIEncoding::IP_VPN_MPLS((
rd,
Prefix::new(afi, pfx_len, pfx_buf),
0u32,
)));
}
#[cfg(feature = "flowspec")]
SAFI::Flowspec => {
let mut nlri_length = cursor.read_u8()?;
let mut filters: Vec<FlowspecFilter> = vec![];
while nlri_length > 0 {
let cur_position = cursor.position();
filters.push(FlowspecFilter::parse(&mut cursor, afi)?);
nlri_length -= (cursor.position() - cur_position) as u8;
}
withdrawn_routes.push(NLRIEncoding::FLOWSPEC(filters));
}
#[cfg(feature = "flowspec")]
SAFI::FlowspecVPN => {
unimplemented!();
}
// DEFAULT
_ => {
if capabilities.EXTENDED_PATH_NLRI_SUPPORT {
while cursor.position() < u64::from(size) {
let path_id = cursor.read_u32::<BigEndian>()?;
let prefix = Prefix::parse(&mut cursor, afi)?;
withdrawn_routes.push(NLRIEncoding::IP_WITH_PATH_ID((prefix, path_id)));
}
} else {
while cursor.position() < u64::from(size) {
let prefix = Prefix::parse(&mut cursor, afi)?;
withdrawn_routes.push(NLRIEncoding::IP(prefix));
}
}
}
};
}
Ok(MPUnreachNLRI {
afi,
safi,
withdrawn_routes,
})
}
/// Encode Multiprotocol Reach NLRI to bytes
pub fn encode(&self, buf: &mut impl Write) -> Result<(), Error> {
buf.write_u16::<BigEndian>(self.afi as u16)?;
buf.write_u8(self.safi as u8)?;
for nlri in &self.withdrawn_routes {
nlri.encode(buf)?;
}
Ok(())
}
}