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|
use std::io::Read;
use std::io::{self, Cursor};
use std::net::Ipv4Addr;
/// A VRRP version 2 packet.
///
/// Packet format
///
/// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// |Version| Type | Virtual Rtr ID| Priority | Count IP Addrs|
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Auth Type | Adver Int | Checksum |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | IP Address (1) |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | . |
/// | . |
/// | . |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | IP Address (n) |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Authentication Data (1) |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Authentication Data (2) |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
#[derive(Debug, PartialEq)]
pub struct VRRPv2 {
pub virtual_router_id: u8,
pub priority: u8,
pub count_ip_addrs: u8,
pub auth_type: VRRPv2AuthType,
pub advertisement_interval: u8,
pub checksum: u16,
pub ip_addrs: Vec<Ipv4Addr>,
}
#[derive(Debug, Clone, PartialEq)]
pub enum VRRPv2Error {
InvalidAuthType,
InvalidChecksum,
InvalidType,
InvalidVersion,
ParseError,
}
#[derive(Debug, PartialEq)]
pub enum VRRPv2AuthType {
VRRPv2AuthNoAuth = 0x00,
VRRPv2AuthReserved1 = 0x01,
VRRPv2AuthReserved2 = 0x02,
}
trait ByteReader {
fn read_u8(&mut self) -> io::Result<u8>;
fn read_u16(&mut self) -> io::Result<u16>;
fn read_u32(&mut self) -> io::Result<u32>;
}
impl<T: AsRef<[u8]>> ByteReader for Cursor<T> {
fn read_u8(&mut self) -> io::Result<u8> {
let mut buffer = [0; 1];
self.read_exact(&mut buffer)?;
Ok(u8::from_be_bytes(buffer))
}
fn read_u16(&mut self) -> io::Result<u16> {
let mut buffer = [0; 2];
self.read_exact(&mut buffer)?;
Ok(u16::from_be_bytes(buffer))
}
fn read_u32(&mut self) -> io::Result<u32> {
let mut buffer = [0; 4];
self.read_exact(&mut buffer)?;
Ok(u32::from_be_bytes(buffer))
}
}
fn parse(bytes: &[u8]) -> Result<VRRPv2, VRRPv2Error> {
let mut rdr = Cursor::new(bytes);
let Ok(vertype) = rdr.read_u8() else {
return Err(VRRPv2Error::ParseError);
};
if (vertype & 0xF) != 1 {
return Err(VRRPv2Error::InvalidType);
}
if (vertype >> 4) != 2 {
return Err(VRRPv2Error::InvalidVersion);
}
let Ok(virtual_router_id) = rdr.read_u8() else {
return Err(VRRPv2Error::ParseError);
};
let Ok(priority) = rdr.read_u8() else {
return Err(VRRPv2Error::ParseError);
};
let Ok(count_ip_addrs) = rdr.read_u8() else {
return Err(VRRPv2Error::ParseError);
};
let Ok(auth_type) = rdr.read_u8() else {
return Err(VRRPv2Error::ParseError);
};
let auth_type = match auth_type {
0 => VRRPv2AuthType::VRRPv2AuthNoAuth,
1 => VRRPv2AuthType::VRRPv2AuthReserved1,
2 => VRRPv2AuthType::VRRPv2AuthReserved2,
_ => return Err(VRRPv2Error::InvalidAuthType),
};
let Ok(advertisement_interval) = rdr.read_u8() else {
return Err(VRRPv2Error::ParseError);
};
let Ok(checksum) = rdr.read_u16() else {
return Err(VRRPv2Error::ParseError);
};
let mut ip_addrs = Vec::with_capacity(count_ip_addrs as usize);
for _i in 0..count_ip_addrs {
let Ok(b) = rdr.read_u32() else {
return Err(VRRPv2Error::ParseError);
};
ip_addrs.push(Ipv4Addr::from(b));
}
Ok(VRRPv2 {
virtual_router_id,
priority,
count_ip_addrs,
auth_type,
advertisement_interval,
checksum,
ip_addrs,
})
}
/// Parse and validate a byte array to construct a VRRPv2 struct.
///
/// # Examples
///
/// ```
/// use vrrpd::vrrpv2::VRRPv2;
/// use vrrpd::vrrpv2::VRRPv2AuthType;
/// use vrrpd::vrrpv2::from_bytes;
/// use std::net::Ipv4Addr;
///
/// let bytes = [
/// 0x21, 0x01, 0x64, 0x01, 0x00, 0x01, 0xba, 0x52, 0xc0, 0xa8, 0x00, 0x01, 0x00, 0x00, 0x00,
/// 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
/// ];
/// let expected = VRRPv2 {
/// virtual_router_id: 1,
/// priority: 100,
/// count_ip_addrs: 1,
/// auth_type: VRRPv2AuthType::VRRPv2AuthNoAuth,
/// checksum: 47698,
/// advertisement_interval: 1,
/// ip_addrs: vec![Ipv4Addr::from([192, 168, 0, 1])],
/// };
/// assert_eq!(from_bytes(&bytes), Ok(expected));
/// ```
pub fn from_bytes(bytes: &[u8]) -> Result<VRRPv2, VRRPv2Error> {
let vrrpv2 = parse(bytes)?;
if checksum(bytes) != 0 {
return Err(VRRPv2Error::InvalidChecksum);
}
Ok(vrrpv2)
}
fn checksum(bytes: &[u8]) -> u16 {
let (chunks, remainder) = bytes.as_chunks::<2>();
let mut sum = chunks
.iter()
.fold(0, |acc, x| acc + u32::from(u16::from_be_bytes(*x)));
if !remainder.is_empty() {
sum += u32::from(remainder[0]);
}
while (sum >> 16) > 0 {
sum = (sum & 0xffff) + (sum >> 16);
}
!(sum as u16)
}
#[test]
fn test_incomplete_bytes() {
let bytes = [0x21, 0x01];
assert_eq!(from_bytes(&bytes), Err(VRRPv2Error::ParseError));
}
#[test]
fn test_invalid_version() {
let bytes = [
0x31, 0x1, 0x2a, 0x0, 0x0, 0x1, 0xb5, 0xfd, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0,
];
assert_eq!(from_bytes(&bytes), Err(VRRPv2Error::InvalidVersion));
}
#[test]
fn test_invalid_type() {
let bytes = [
0x20, 0x2a, 0x64, 0x1, 0x0, 0x1, 0xaa, 0x29, 0xc0, 0xa8, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0,
];
assert_eq!(from_bytes(&bytes), Err(VRRPv2Error::InvalidType));
}
#[test]
fn test_invalid_auth_type() {
let bytes = [
0x21, 0x01, 0x64, 0x01, 0x03, 0x01, 0xba, 0x52, 0xc0, 0xa8, 0x00, 0x01, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
];
assert_eq!(from_bytes(&bytes), Err(VRRPv2Error::InvalidAuthType));
}
#[test]
fn test_invalid_checksum() {
let bytes = [
0x21, 0x01, 0x64, 0x01, 0x00, 0x01, 0xbb, 0x52, 0xc0, 0xa8, 0x00, 0x01, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
];
assert_eq!(from_bytes(&bytes), Err(VRRPv2Error::InvalidChecksum));
}
#[test]
fn test_checksum() {
let bytes = [0x00, 0x01, 0xf2, 0x03, 0xf4, 0xf5, 0xf6, 0xf7];
assert_eq!(checksum(&bytes), 0x220d);
}
#[test]
fn test_checksum_singlebyte() {
let bytes = [0; 1];
assert_eq!(checksum(&bytes), 0xffff);
}
#[test]
fn test_checksum_twobytes() {
let bytes = [0x00, 0xff];
assert_eq!(checksum(&bytes), 0xff00);
}
#[test]
fn test_checksum_another() {
let bytes = [0xe3, 0x4f, 0x23, 0x96, 0x44, 0x27, 0x99, 0xf3];
assert_eq!(checksum(&bytes), 0x1aff);
}
|
