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Improved error handling
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Reintroduces use of unstable features, though a number of them are
stabilized in fix rust-lang/rust#23430
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@willem66745
willem66745 committed Mar 20, 2015
1 parent 27f7164 commit 610c48b
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Showing 2 changed files with 51 additions and 46 deletions.
6 changes: 3 additions & 3 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ extern crate byteorder;

mod ntp;

use std::net::{UdpSocket};
use std::net::UdpSocket;
use time::Timespec;

const NTP_PORT: u16 = 123;
Expand All @@ -16,7 +16,7 @@ const UDP_LOCAL: &'static str = "0.0.0.0:35000";
/// * `host` - The NTP server (i.e. sundial.columbia.edu).
pub fn retrieve_ntp_timestamp(host: &str) -> Result<Timespec, std::io::Error> {
let header = ntp::NTPHeader::new();
let message = header.encode();
let message = try!(header.encode());

let socket = try!(UdpSocket::bind(UDP_LOCAL));

Expand All @@ -30,7 +30,7 @@ pub fn retrieve_ntp_timestamp(host: &str) -> Result<Timespec, std::io::Error> {

drop(socket);

let header = ntp::NTPHeader::decode(amt, &buf);
let header = try!(ntp::NTPHeader::decode(amt, &buf));

Ok(header.transmit_timestamp.as_timespec())
}
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91 changes: 48 additions & 43 deletions src/ntp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@ use std::num::Float;
use time::Timespec;
use std::io::Cursor;
use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
use std::io::Error as IoError;
use std::io::ErrorKind as IoErrorKind;

const NTP_CLIENT: u8 = 3;
const NTP_HEADER_SIZE: usize = 48; // 12 words
Expand Down Expand Up @@ -61,66 +63,69 @@ impl NTPHeader {
}
}

fn encode_first_word<T>(&self, w: &mut T) where T: WriteBytesExt {
w.write_u8(self.leap << LEAP_SHIFT | self.version << VERSION_SHIFT | self.mode).unwrap();
w.write_u8(self.stratum).unwrap();
w.write_u8(self.poll).unwrap();
w.write_u8(self.precision).unwrap();
fn encode_first_word<T>(&self, w: &mut T) -> Result<(), IoError> where T: WriteBytesExt {
try!(w.write_u8(self.leap << LEAP_SHIFT | self.version << VERSION_SHIFT | self.mode));
try!(w.write_u8(self.stratum));
try!(w.write_u8(self.poll));
try!(w.write_u8(self.precision));
Ok(())
}

pub fn encode(&self) -> Vec<u8> {
pub fn encode(&self) -> Result<Vec<u8>, IoError> {
let mut vec = Vec::<u8>::new();

// TODO: since Vec still implements old_io::Write trait the next 4 lines does not compile
//vec.write_u8(self.leap << LEAP_SHIFT | self.version << VERSION_SHIFT | self.mode).unwrap();
//vec.write_u8(self.stratum).unwrap();
//vec.write_u8(self.poll).unwrap();
//vec.write_u8(self.precision).unwrap();
//try!(vec.write_u8(self.leap << LEAP_SHIFT | self.version << VERSION_SHIFT | self.mode));
//try!(vec.write_u8(self.stratum));
//try!(vec.write_u8(self.poll));
//try!(vec.write_u8(self.precision));

// TODO: remove workaround when possible
self.encode_first_word(&mut vec);

vec.write_u32::<BigEndian>(self.root_delay).unwrap();
vec.write_u32::<BigEndian>(self.root_dispersion).unwrap();
vec.write_u32::<BigEndian>(self.reference_id).unwrap();
vec.write_u32::<BigEndian>(self.reference_timestamp.seconds).unwrap();
vec.write_u32::<BigEndian>(self.reference_timestamp.fraction).unwrap();
vec.write_u32::<BigEndian>(self.origin_timestamp.seconds).unwrap();
vec.write_u32::<BigEndian>(self.origin_timestamp.fraction).unwrap();
vec.write_u32::<BigEndian>(self.receive_timestamp.seconds).unwrap();
vec.write_u32::<BigEndian>(self.receive_timestamp.fraction).unwrap();
vec.write_u32::<BigEndian>(self.transmit_timestamp.seconds).unwrap();
vec.write_u32::<BigEndian>(self.transmit_timestamp.fraction).unwrap();
vec
try!(self.encode_first_word(&mut vec));

try!(vec.write_u32::<BigEndian>(self.root_delay));
try!(vec.write_u32::<BigEndian>(self.root_dispersion));
try!(vec.write_u32::<BigEndian>(self.reference_id));
try!(vec.write_u32::<BigEndian>(self.reference_timestamp.seconds));
try!(vec.write_u32::<BigEndian>(self.reference_timestamp.fraction));
try!(vec.write_u32::<BigEndian>(self.origin_timestamp.seconds));
try!(vec.write_u32::<BigEndian>(self.origin_timestamp.fraction));
try!(vec.write_u32::<BigEndian>(self.receive_timestamp.seconds));
try!(vec.write_u32::<BigEndian>(self.receive_timestamp.fraction));
try!(vec.write_u32::<BigEndian>(self.transmit_timestamp.seconds));
try!(vec.write_u32::<BigEndian>(self.transmit_timestamp.fraction));
Ok(vec)
}

pub fn decode(size: usize, buf: & [u8]) -> NTPHeader {
pub fn decode(size: usize, buf: & [u8]) -> Result<NTPHeader, IoError> {
let mut reader = Cursor::new(buf);
let mut header = NTPHeader::new();

if size < NTP_HEADER_SIZE {
panic!("{} bytes expected in NTP header; {} bytes received", NTP_HEADER_SIZE, size);
return Err(IoError::new(IoErrorKind::Other,
"Unexpected number of bytes in NTP datagram",
Option::Some(format!("{} bytes expected in NTP header; {} bytes received", NTP_HEADER_SIZE, size))));
}

let leap_version_mode = reader.read_u8().unwrap();
let leap_version_mode = try!(reader.read_u8());
header.leap = (leap_version_mode >> LEAP_SHIFT) & 0b11;
header.version = (leap_version_mode >> VERSION_SHIFT) & 0b111;
header.mode = leap_version_mode & 0b111;
header.stratum = reader.read_u8().unwrap();
header.poll = reader.read_u8().unwrap();
header.precision = reader.read_u8().unwrap();
header.root_delay = reader.read_u32::<BigEndian>().unwrap();
header.root_dispersion = reader.read_u32::<BigEndian>().unwrap();
header.reference_id = reader.read_u32::<BigEndian>().unwrap();
header.reference_timestamp.seconds = reader.read_u32::<BigEndian>().unwrap();
header.reference_timestamp.fraction = reader.read_u32::<BigEndian>().unwrap();
header.origin_timestamp.seconds = reader.read_u32::<BigEndian>().unwrap();
header.origin_timestamp.fraction = reader.read_u32::<BigEndian>().unwrap();
header.receive_timestamp.seconds = reader.read_u32::<BigEndian>().unwrap();
header.receive_timestamp.fraction = reader.read_u32::<BigEndian>().unwrap();
header.transmit_timestamp.seconds = reader.read_u32::<BigEndian>().unwrap();
header.transmit_timestamp.fraction = reader.read_u32::<BigEndian>().unwrap();

header
header.stratum = try!(reader.read_u8());
header.poll = try!(reader.read_u8());
header.precision = try!(reader.read_u8());
header.root_delay = try!(reader.read_u32::<BigEndian>());
header.root_dispersion = try!(reader.read_u32::<BigEndian>());
header.reference_id = try!(reader.read_u32::<BigEndian>());
header.reference_timestamp.seconds = try!(reader.read_u32::<BigEndian>());
header.reference_timestamp.fraction = try!(reader.read_u32::<BigEndian>());
header.origin_timestamp.seconds = try!(reader.read_u32::<BigEndian>());
header.origin_timestamp.fraction = try!(reader.read_u32::<BigEndian>());
header.receive_timestamp.seconds = try!(reader.read_u32::<BigEndian>());
header.receive_timestamp.fraction = try!(reader.read_u32::<BigEndian>());
header.transmit_timestamp.seconds = try!(reader.read_u32::<BigEndian>());
header.transmit_timestamp.fraction = try!(reader.read_u32::<BigEndian>());

Ok(header)
}
}

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