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|
use nom::bytes::streaming::take;
use nom::combinator::{complete, map, map_parser, opt};
use nom::error::{make_error, ErrorKind};
use nom::multi::many1;
use nom::number::streaming::be_u8;
pub use nom::{Err, IResult};
use nom_derive::*;
#[derive(Debug, PartialEq)]
pub enum NtpPacket<'a> {
V3(NtpV3Packet<'a>),
V4(NtpV4Packet<'a>),
}
#[derive(Clone, Copy, Debug, Eq, PartialEq, NomBE)]
pub struct NtpMode(pub u8);
#[allow(non_upper_case_globals)]
impl NtpMode {
pub const Reserved: NtpMode = NtpMode(0);
pub const SymmetricActive: NtpMode = NtpMode(1);
pub const SymmetricPassive: NtpMode = NtpMode(2);
pub const Client: NtpMode = NtpMode(3);
pub const Server: NtpMode = NtpMode(4);
pub const Broadcast: NtpMode = NtpMode(5);
pub const NtpControlMessage: NtpMode = NtpMode(6);
pub const Private: NtpMode = NtpMode(7);
}
/// An NTP version 3 packet
#[derive(Debug, PartialEq, NomBE)]
pub struct NtpV3Packet<'a> {
#[nom(PreExec = "let (i, b0) = be_u8(i)?;")]
#[nom(Value(b0 >> 6))]
pub li: u8,
#[nom(Value((b0 >> 3) & 0b111))]
pub version: u8,
#[nom(Value(NtpMode(b0 & 0b111)))]
pub mode: NtpMode,
pub stratum: u8,
pub poll: i8,
pub precision: i8,
pub root_delay: u32,
pub root_dispersion: u32,
pub ref_id: u32,
pub ts_ref: u64,
pub ts_orig: u64,
pub ts_recv: u64,
pub ts_xmit: u64,
#[nom(Parse = "opt(complete(take(12usize)))")]
pub authenticator: Option<&'a [u8]>,
}
/// An NTP version 4 packet
#[derive(Debug, PartialEq, NomBE)]
pub struct NtpV4Packet<'a> {
#[nom(PreExec = "let (i, b0) = be_u8(i)?;")]
#[nom(Value(b0 >> 6))]
pub li: u8,
#[nom(Value((b0 >> 3) & 0b111))]
pub version: u8,
#[nom(Value(NtpMode(b0 & 0b111)))]
pub mode: NtpMode,
pub stratum: u8,
pub poll: i8,
pub precision: i8,
pub root_delay: u32,
pub root_dispersion: u32,
pub ref_id: u32,
pub ts_ref: u64,
pub ts_orig: u64,
pub ts_recv: u64,
pub ts_xmit: u64,
#[nom(Parse = "try_parse_extensions")]
pub extensions: Vec<NtpExtension<'a>>,
#[nom(Cond(!i.is_empty()))]
pub auth: Option<NtpMac<'a>>,
}
impl<'a> NtpV4Packet<'a> {
pub fn get_precision(&self) -> f32 {
2.0_f32.powf(self.precision as f32)
}
}
#[derive(Debug, PartialEq, NomBE)]
pub struct NtpExtension<'a> {
pub field_type: u16,
pub length: u16,
#[nom(Parse = "take(length)")]
pub value: &'a [u8],
/*padding*/
}
#[derive(Debug, PartialEq, NomBE)]
pub struct NtpMac<'a> {
pub key_id: u32,
#[nom(Parse = "take(16usize)")]
pub mac: &'a [u8],
}
#[inline]
pub fn parse_ntp_extension(i: &[u8]) -> IResult<&[u8], NtpExtension> {
NtpExtension::parse(i)
}
// Attempt to parse extensions.
//
// See section 7.5 of [RFC5905] and [RFC7822]:
// In NTPv4, one or more extension fields can be inserted after the
// header and before the MAC, which is always present when an extension
// field is present.
//
// So:
// if == 20, only MAC
// if > 20, ext + MAC
// if == 0, nothing
// else error
fn try_parse_extensions(i: &[u8]) -> IResult<&[u8], Vec<NtpExtension>> {
if i.is_empty() || i.len() == 20 {
// if empty, or if remaining length is exactly the MAC length (20), assume we do not have
// extensions
return Ok((i, Vec::new()));
}
if i.len() < 20 {
return Err(Err::Error(make_error(i, ErrorKind::Eof)));
}
map_parser(take(i.len() - 20), many1(complete(parse_ntp_extension)))(i)
}
/// Parse an NTP version 3 packet (RFC 1305)
#[inline]
pub fn parse_ntpv3(i: &[u8]) -> IResult<&[u8], NtpV3Packet> {
NtpV3Packet::parse(i)
}
/// Parse an NTP version 4 packet (RFC 1305)
#[inline]
pub fn parse_ntpv4(i: &[u8]) -> IResult<&[u8], NtpV4Packet> {
NtpV4Packet::parse(i)
}
/// Parse an NTP packet, version 3 or 4
#[inline]
pub fn parse_ntp(i: &[u8]) -> IResult<&[u8], NtpPacket> {
let (_, b0) = be_u8(i)?;
match (b0 >> 3) & 0b111 {
3 => map(NtpV3Packet::parse, NtpPacket::V3)(i),
4 => map(NtpV4Packet::parse, NtpPacket::V4)(i),
_ => Err(Err::Error(make_error(i, ErrorKind::Tag))),
}
}
#[cfg(test)]
mod tests {
use crate::ntp::*;
static NTP_REQ1: &[u8] = &[
0xd9, 0x00, 0x0a, 0xfa, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x90, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc5, 0x02, 0x04, 0xec, 0xec,
0x42, 0xee, 0x92,
];
#[test]
fn test_ntp_packet_simple() {
let empty = &b""[..];
let bytes = NTP_REQ1;
let expected = NtpV4Packet {
li: 3,
version: 3,
mode: NtpMode::SymmetricActive,
stratum: 0,
poll: 10,
precision: -6,
root_delay: 0,
root_dispersion: 0x010290,
ref_id: 0,
ts_ref: 0,
ts_orig: 0,
ts_recv: 0,
ts_xmit: 14195914391047827090u64,
extensions: Vec::new(),
auth: None,
};
let res = parse_ntpv4(&bytes);
assert_eq!(res, Ok((empty, expected)));
}
static NTP_REQ2: &[u8] = &[
0x23, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xcc, 0x25, 0xcc, 0x13, 0x2b,
0x02, 0x10, 0x00, 0x00, 0x00, 0x00, 0x01, 0x52, 0x80, 0x0c, 0x2b, 0x59, 0x00, 0x64, 0x66,
0x84, 0xf4, 0x4c, 0xa4, 0xee, 0xce, 0x12, 0xb8,
];
#[test]
fn test_ntp_packet_mac() {
let empty = &b""[..];
let bytes = NTP_REQ2;
let expected = NtpV4Packet {
li: 0,
version: 4,
mode: NtpMode::Client,
stratum: 0,
poll: 0,
precision: 0,
root_delay: 12,
root_dispersion: 0,
ref_id: 0,
ts_ref: 0,
ts_orig: 0,
ts_recv: 0,
ts_xmit: 14710388140573593600,
extensions: Vec::new(),
auth: Some(NtpMac {
key_id: 1,
mac: &bytes[52..],
}),
};
let res = parse_ntpv4(&bytes);
assert_eq!(res, Ok((empty, expected)));
}
static NTP_REQ2B: &[u8] = &[
0x23, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xcc, 0x25, 0xcc, 0x13, 0x2b,
0x02, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x52, 0x80, 0x0c, 0x2b,
0x59, 0x00, 0x64, 0x66, 0x84, 0xf4, 0x4c, 0xa4, 0xee, 0xce, 0x12, 0xb8,
];
#[test]
fn test_ntp_packet_extension() {
let empty = &b""[..];
let bytes = NTP_REQ2B;
let expected = NtpV4Packet {
li: 0,
version: 4,
mode: NtpMode::Client,
stratum: 0,
poll: 0,
precision: 0,
root_delay: 12,
root_dispersion: 0,
ref_id: 0,
ts_ref: 0,
ts_orig: 0,
ts_recv: 0,
ts_xmit: 14710388140573593600,
extensions: vec![NtpExtension {
field_type: 0,
length: 0,
value: empty,
}],
auth: Some(NtpMac {
key_id: 1,
mac: &bytes[56..],
}),
};
let res = parse_ntpv4(&bytes);
assert_eq!(res, Ok((empty, expected)));
}
// from wireshark test captures 'ntp.pcap'
static NTPV3_REQ: &[u8] = &[
0x1b, 0x04, 0x06, 0xf5, 0x00, 0x00, 0x10, 0x0d, 0x00, 0x00, 0x05, 0x57, 0x82, 0xdc, 0x18,
0x18, 0xba, 0x29, 0x66, 0x36, 0x7d, 0xd0, 0x00, 0x00, 0xba, 0x29, 0x66, 0x36, 0x7d, 0x58,
0x40, 0x00, 0xba, 0x29, 0x66, 0x36, 0x7d, 0xd0, 0x00, 0x00, 0xba, 0x29, 0x66, 0x76, 0x7d,
0x50, 0x50, 0x00,
];
#[test]
fn test_ntp_packet_v3() {
let empty = &b""[..];
let bytes = NTPV3_REQ;
let expected = NtpV3Packet {
li: 0,
version: 3,
mode: NtpMode::Client,
stratum: 4,
poll: 6,
precision: -11,
root_delay: 4109,
root_dispersion: 0x0557,
ref_id: 0x82dc1818,
ts_ref: 0xba296636_7dd00000,
ts_orig: 0xba296636_7d584000,
ts_recv: 0xba296636_7dd00000,
ts_xmit: 0xba296676_7d505000,
authenticator: None,
};
let res = NtpV3Packet::parse(&bytes);
assert_eq!(res, Ok((empty, expected)));
}
}
|
