_ Git - rust-lightning/blob - lightning/src/util/ser.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! A very simple serialization framework which is used to serialize/deserialize messages as well
  11 //! as [`ChannelManager`]s and [`ChannelMonitor`]s.
  12 //!
  13 //! [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
  14 //! [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
  15
  16 use crate::prelude::*;
  17 use crate::io::{self, Read, Seek, Write};
  18 use crate::io_extras::{copy, sink};
  19 use core::hash::Hash;
  20 use crate::sync::Mutex;
  21 use core::cmp;
  22 use core::convert::TryFrom;
  23 use core::ops::Deref;
  24
  25 use alloc::collections::BTreeMap;
  26
  27 use bitcoin::secp256k1::{PublicKey, SecretKey};
  28 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
  29 use bitcoin::secp256k1::ecdsa;
  30 use bitcoin::secp256k1::schnorr;
  31 use bitcoin::blockdata::constants::ChainHash;
  32 use bitcoin::blockdata::script::Script;
  33 use bitcoin::blockdata::transaction::{OutPoint, Transaction, TxOut};
  34 use bitcoin::consensus;
  35 use bitcoin::consensus::Encodable;
  36 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
  37 use bitcoin::hash_types::{Txid, BlockHash};
  38 use core::marker::Sized;
  39 use core::time::Duration;
  40 use crate::ln::msgs::DecodeError;
  41 use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
  42
  43 use crate::util::byte_utils::{be48_to_array, slice_to_be48};
  44
  45 /// serialization buffer size
  46 pub const MAX_BUF_SIZE: usize = 64 * 1024;
  47
  48 /// A simplified version of [`std::io::Write`] that exists largely for backwards compatibility.
  49 /// An impl is provided for any type that also impls [`std::io::Write`].
  50 ///
  51 /// (C-not exported) as we only export serialization to/from byte arrays instead
  52 pub trait Writer {
  53         /// Writes the given buf out. See std::io::Write::write_all for more
  54         fn write_all(&mut self, buf: &[u8]) -> Result<(), io::Error>;
  55 }
  56
  57 impl<W: Write> Writer for W {
  58         #[inline]
  59         fn write_all(&mut self, buf: &[u8]) -> Result<(), io::Error> {
  60                 <Self as io::Write>::write_all(self, buf)
  61         }
  62 }
  63
  64 pub(crate) struct WriterWriteAdaptor<'a, W: Writer + 'a>(pub &'a mut W);
  65 impl<'a, W: Writer + 'a> Write for WriterWriteAdaptor<'a, W> {
  66         #[inline]
  67         fn write_all(&mut self, buf: &[u8]) -> Result<(), io::Error> {
  68                 self.0.write_all(buf)
  69         }
  70         #[inline]
  71         fn write(&mut self, buf: &[u8]) -> Result<usize, io::Error> {
  72                 self.0.write_all(buf)?;
  73                 Ok(buf.len())
  74         }
  75         #[inline]
  76         fn flush(&mut self) -> Result<(), io::Error> {
  77                 Ok(())
  78         }
  79 }
  80
  81 pub(crate) struct VecWriter(pub Vec<u8>);
  82 impl Writer for VecWriter {
  83         #[inline]
  84         fn write_all(&mut self, buf: &[u8]) -> Result<(), io::Error> {
  85                 self.0.extend_from_slice(buf);
  86                 Ok(())
  87         }
  88 }
  89
  90 /// Writer that only tracks the amount of data written - useful if you need to calculate the length
  91 /// of some data when serialized but don't yet need the full data.
  92 pub struct LengthCalculatingWriter(pub usize);
  93 impl Writer for LengthCalculatingWriter {
  94         #[inline]
  95         fn write_all(&mut self, buf: &[u8]) -> Result<(), io::Error> {
  96                 self.0 += buf.len();
  97                 Ok(())
  98         }
  99 }
 100
 101 /// Essentially [`std::io::Take`] but a bit simpler and with a method to walk the underlying stream
 102 /// forward to ensure we always consume exactly the fixed length specified.
 103 pub struct FixedLengthReader<R: Read> {
 104         read: R,
 105         bytes_read: u64,
 106         total_bytes: u64,
 107 }
 108 impl<R: Read> FixedLengthReader<R> {
 109         /// Returns a new [`FixedLengthReader`].
 110         pub fn new(read: R, total_bytes: u64) -> Self {
 111                 Self { read, bytes_read: 0, total_bytes }
 112         }
 113
 114         /// Returns whether some bytes are remaining or not.
 115         #[inline]
 116         pub fn bytes_remain(&mut self) -> bool {
 117                 self.bytes_read != self.total_bytes
 118         }
 119
 120         /// Consumes the remaining bytes.
 121         #[inline]
 122         pub fn eat_remaining(&mut self) -> Result<(), DecodeError> {
 123                 copy(self, &mut sink()).unwrap();
 124                 if self.bytes_read != self.total_bytes {
 125                         Err(DecodeError::ShortRead)
 126                 } else {
 127                         Ok(())
 128                 }
 129         }
 130 }
 131 impl<R: Read> Read for FixedLengthReader<R> {
 132         #[inline]
 133         fn read(&mut self, dest: &mut [u8]) -> Result<usize, io::Error> {
 134                 if self.total_bytes == self.bytes_read {
 135                         Ok(0)
 136                 } else {
 137                         let read_len = cmp::min(dest.len() as u64, self.total_bytes - self.bytes_read);
 138                         match self.read.read(&mut dest[0..(read_len as usize)]) {
 139                                 Ok(v) => {
 140                                         self.bytes_read += v as u64;
 141                                         Ok(v)
 142                                 },
 143                                 Err(e) => Err(e),
 144                         }
 145                 }
 146         }
 147 }
 148
 149 impl<R: Read> LengthRead for FixedLengthReader<R> {
 150         #[inline]
 151         fn total_bytes(&self) -> u64 {
 152                 self.total_bytes
 153         }
 154 }
 155
 156 /// A [`Read`] implementation which tracks whether any bytes have been read at all. This allows us to distinguish
 157 /// between "EOF reached before we started" and "EOF reached mid-read".
 158 pub struct ReadTrackingReader<R: Read> {
 159         read: R,
 160         /// Returns whether we have read from this reader or not yet.
 161         pub have_read: bool,
 162 }
 163 impl<R: Read> ReadTrackingReader<R> {
 164         /// Returns a new [`ReadTrackingReader`].
 165         pub fn new(read: R) -> Self {
 166                 Self { read, have_read: false }
 167         }
 168 }
 169 impl<R: Read> Read for ReadTrackingReader<R> {
 170         #[inline]
 171         fn read(&mut self, dest: &mut [u8]) -> Result<usize, io::Error> {
 172                 match self.read.read(dest) {
 173                         Ok(0) => Ok(0),
 174                         Ok(len) => {
 175                                 self.have_read = true;
 176                                 Ok(len)
 177                         },
 178                         Err(e) => Err(e),
 179                 }
 180         }
 181 }
 182
 183 /// A trait that various LDK types implement allowing them to be written out to a [`Writer`].
 184 ///
 185 /// (C-not exported) as we only export serialization to/from byte arrays instead
 186 pub trait Writeable {
 187         /// Writes `self` out to the given [`Writer`].
 188         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error>;
 189
 190         /// Writes `self` out to a `Vec<u8>`.
 191         fn encode(&self) -> Vec<u8> {
 192                 let mut msg = VecWriter(Vec::new());
 193                 self.write(&mut msg).unwrap();
 194                 msg.0
 195         }
 196
 197         /// Writes `self` out to a `Vec<u8>`.
 198         #[cfg(test)]
 199         fn encode_with_len(&self) -> Vec<u8> {
 200                 let mut msg = VecWriter(Vec::new());
 201                 0u16.write(&mut msg).unwrap();
 202                 self.write(&mut msg).unwrap();
 203                 let len = msg.0.len();
 204                 msg.0[..2].copy_from_slice(&(len as u16 - 2).to_be_bytes());
 205                 msg.0
 206         }
 207
 208         /// Gets the length of this object after it has been serialized. This can be overridden to
 209         /// optimize cases where we prepend an object with its length.
 210         // Note that LLVM optimizes this away in most cases! Check that it isn't before you override!
 211         #[inline]
 212         fn serialized_length(&self) -> usize {
 213                 let mut len_calc = LengthCalculatingWriter(0);
 214                 self.write(&mut len_calc).expect("No in-memory data may fail to serialize");
 215                 len_calc.0
 216         }
 217 }
 218
 219 impl<'a, T: Writeable> Writeable for &'a T {
 220         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> { (*self).write(writer) }
 221 }
 222
 223 /// A trait that various LDK types implement allowing them to be read in from a [`Read`].
 224 ///
 225 /// (C-not exported) as we only export serialization to/from byte arrays instead
 226 pub trait Readable
 227         where Self: Sized
 228 {
 229         /// Reads a `Self` in from the given [`Read`].
 230         fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError>;
 231 }
 232
 233 /// A trait that various LDK types implement allowing them to be read in from a
 234 /// [`Read`]` + `[`Seek`].
 235 pub(crate) trait SeekReadable where Self: Sized {
 236         /// Reads a `Self` in from the given [`Read`].
 237         fn read<R: Read + Seek>(reader: &mut R) -> Result<Self, DecodeError>;
 238 }
 239
 240 /// A trait that various higher-level LDK types implement allowing them to be read in
 241 /// from a [`Read`] given some additional set of arguments which is required to deserialize.
 242 ///
 243 /// (C-not exported) as we only export serialization to/from byte arrays instead
 244 pub trait ReadableArgs<P>
 245         where Self: Sized
 246 {
 247         /// Reads a `Self` in from the given [`Read`].
 248         fn read<R: Read>(reader: &mut R, params: P) -> Result<Self, DecodeError>;
 249 }
 250
 251 /// A [`std::io::Read`] that also provides the total bytes available to be read.
 252 pub(crate) trait LengthRead: Read {
 253         /// The total number of bytes available to be read.
 254         fn total_bytes(&self) -> u64;
 255 }
 256
 257 /// A trait that various higher-level LDK types implement allowing them to be read in
 258 /// from a Read given some additional set of arguments which is required to deserialize, requiring
 259 /// the implementer to provide the total length of the read.
 260 pub(crate) trait LengthReadableArgs<P> where Self: Sized
 261 {
 262         /// Reads a `Self` in from the given [`LengthRead`].
 263         fn read<R: LengthRead>(reader: &mut R, params: P) -> Result<Self, DecodeError>;
 264 }
 265
 266 /// A trait that various higher-level LDK types implement allowing them to be read in
 267 /// from a [`Read`], requiring the implementer to provide the total length of the read.
 268 pub(crate) trait LengthReadable where Self: Sized
 269 {
 270         /// Reads a `Self` in from the given [`LengthRead`].
 271         fn read<R: LengthRead>(reader: &mut R) -> Result<Self, DecodeError>;
 272 }
 273
 274 /// A trait that various LDK types implement allowing them to (maybe) be read in from a [`Read`].
 275 ///
 276 /// (C-not exported) as we only export serialization to/from byte arrays instead
 277 pub trait MaybeReadable
 278         where Self: Sized
 279 {
 280         /// Reads a `Self` in from the given [`Read`].
 281         fn read<R: Read>(reader: &mut R) -> Result<Option<Self>, DecodeError>;
 282 }
 283
 284 impl<T: Readable> MaybeReadable for T {
 285         #[inline]
 286         fn read<R: Read>(reader: &mut R) -> Result<Option<T>, DecodeError> {
 287                 Ok(Some(Readable::read(reader)?))
 288         }
 289 }
 290
 291 /// Wrapper to read a required (non-optional) TLV record.
 292 pub struct RequiredWrapper<T>(pub Option<T>);
 293 impl<T: Readable> Readable for RequiredWrapper<T> {
 294         #[inline]
 295         fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
 296                 Ok(Self(Some(Readable::read(reader)?)))
 297         }
 298 }
 299 impl<A, T: ReadableArgs<A>> ReadableArgs<A> for RequiredWrapper<T> {
 300         #[inline]
 301         fn read<R: Read>(reader: &mut R, args: A) -> Result<Self, DecodeError> {
 302                 Ok(Self(Some(ReadableArgs::read(reader, args)?)))
 303         }
 304 }
 305 /// When handling `default_values`, we want to map the default-value T directly
 306 /// to a `RequiredWrapper<T>` in a way that works for `field: T = t;` as
 307 /// well. Thus, we assume `Into<T> for T` does nothing and use that.
 308 impl<T> From<T> for RequiredWrapper<T> {
 309         fn from(t: T) -> RequiredWrapper<T> { RequiredWrapper(Some(t)) }
 310 }
 311
 312 /// Wrapper to read a required (non-optional) TLV record that may have been upgraded without
 313 /// backwards compat.
 314 pub struct UpgradableRequired<T: MaybeReadable>(pub Option<T>);
 315 impl<T: MaybeReadable> MaybeReadable for UpgradableRequired<T> {
 316         #[inline]
 317         fn read<R: Read>(reader: &mut R) -> Result<Option<Self>, DecodeError> {
 318                 let tlv = MaybeReadable::read(reader)?;
 319                 if let Some(tlv) = tlv { return Ok(Some(Self(Some(tlv)))) }
 320                 Ok(None)
 321         }
 322 }
 323
 324 pub(crate) struct U48(pub u64);
 325 impl Writeable for U48 {
 326         #[inline]
 327         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 328                 writer.write_all(&be48_to_array(self.0))
 329         }
 330 }
 331 impl Readable for U48 {
 332         #[inline]
 333         fn read<R: Read>(reader: &mut R) -> Result<U48, DecodeError> {
 334                 let mut buf = [0; 6];
 335                 reader.read_exact(&mut buf)?;
 336                 Ok(U48(slice_to_be48(&buf)))
 337         }
 338 }
 339
 340 /// Lightning TLV uses a custom variable-length integer called `BigSize`. It is similar to Bitcoin's
 341 /// variable-length integers except that it is serialized in big-endian instead of little-endian.
 342 ///
 343 /// Like Bitcoin's variable-length integer, it exhibits ambiguity in that certain values can be
 344 /// encoded in several different ways, which we must check for at deserialization-time. Thus, if
 345 /// you're looking for an example of a variable-length integer to use for your own project, move
 346 /// along, this is a rather poor design.
 347 pub struct BigSize(pub u64);
 348 impl Writeable for BigSize {
 349         #[inline]
 350         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 351                 match self.0 {
 352                         0...0xFC => {
 353                                 (self.0 as u8).write(writer)
 354                         },
 355                         0xFD...0xFFFF => {
 356                                 0xFDu8.write(writer)?;
 357                                 (self.0 as u16).write(writer)
 358                         },
 359                         0x10000...0xFFFFFFFF => {
 360                                 0xFEu8.write(writer)?;
 361                                 (self.0 as u32).write(writer)
 362                         },
 363                         _ => {
 364                                 0xFFu8.write(writer)?;
 365                                 (self.0 as u64).write(writer)
 366                         },
 367                 }
 368         }
 369 }
 370 impl Readable for BigSize {
 371         #[inline]
 372         fn read<R: Read>(reader: &mut R) -> Result<BigSize, DecodeError> {
 373                 let n: u8 = Readable::read(reader)?;
 374                 match n {
 375                         0xFF => {
 376                                 let x: u64 = Readable::read(reader)?;
 377                                 if x < 0x100000000 {
 378                                         Err(DecodeError::InvalidValue)
 379                                 } else {
 380                                         Ok(BigSize(x))
 381                                 }
 382                         }
 383                         0xFE => {
 384                                 let x: u32 = Readable::read(reader)?;
 385                                 if x < 0x10000 {
 386                                         Err(DecodeError::InvalidValue)
 387                                 } else {
 388                                         Ok(BigSize(x as u64))
 389                                 }
 390                         }
 391                         0xFD => {
 392                                 let x: u16 = Readable::read(reader)?;
 393                                 if x < 0xFD {
 394                                         Err(DecodeError::InvalidValue)
 395                                 } else {
 396                                         Ok(BigSize(x as u64))
 397                                 }
 398                         }
 399                         n => Ok(BigSize(n as u64))
 400                 }
 401         }
 402 }
 403
 404 /// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
 405 /// primarily targets that, we must as well. However, because we may serialize objects that have
 406 /// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
 407 /// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
 408 /// "read eight more bytes".
 409 ///
 410 /// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
 411 /// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
 412 /// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
 413 struct CollectionLength(pub u64);
 414 impl Writeable for CollectionLength {
 415         #[inline]
 416         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 417                 if self.0 < 0xffff {
 418                         (self.0 as u16).write(writer)
 419                 } else {
 420                         0xffffu16.write(writer)?;
 421                         (self.0 - 0xffff).write(writer)
 422                 }
 423         }
 424 }
 425
 426 impl Readable for CollectionLength {
 427         #[inline]
 428         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 429                 let mut val: u64 = <u16 as Readable>::read(r)? as u64;
 430                 if val == 0xffff {
 431                         val = <u64 as Readable>::read(r)?
 432                                 .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
 433                 }
 434                 Ok(CollectionLength(val))
 435         }
 436 }
 437
 438 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 439 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 440 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
 441 #[cfg_attr(test, derive(PartialEq, Eq, Debug))]
 442 pub(crate) struct HighZeroBytesDroppedBigSize<T>(pub T);
 443
 444 macro_rules! impl_writeable_primitive {
 445         ($val_type:ty, $len: expr) => {
 446                 impl Writeable for $val_type {
 447                         #[inline]
 448                         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 449                                 writer.write_all(&self.to_be_bytes())
 450                         }
 451                 }
 452                 impl Writeable for HighZeroBytesDroppedBigSize<$val_type> {
 453                         #[inline]
 454                         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 455                                 // Skip any full leading 0 bytes when writing (in BE):
 456                                 writer.write_all(&self.0.to_be_bytes()[(self.0.leading_zeros()/8) as usize..$len])
 457                         }
 458                 }
 459                 impl Readable for $val_type {
 460                         #[inline]
 461                         fn read<R: Read>(reader: &mut R) -> Result<$val_type, DecodeError> {
 462                                 let mut buf = [0; $len];
 463                                 reader.read_exact(&mut buf)?;
 464                                 Ok(<$val_type>::from_be_bytes(buf))
 465                         }
 466                 }
 467                 impl Readable for HighZeroBytesDroppedBigSize<$val_type> {
 468                         #[inline]
 469                         fn read<R: Read>(reader: &mut R) -> Result<HighZeroBytesDroppedBigSize<$val_type>, DecodeError> {
 470                                 // We need to accept short reads (read_len == 0) as "EOF" and handle them as simply
 471                                 // the high bytes being dropped. To do so, we start reading into the middle of buf
 472                                 // and then convert the appropriate number of bytes with extra high bytes out of
 473                                 // buf.
 474                                 let mut buf = [0; $len*2];
 475                                 let mut read_len = reader.read(&mut buf[$len..])?;
 476                                 let mut total_read_len = read_len;
 477                                 while read_len != 0 && total_read_len != $len {
 478                                         read_len = reader.read(&mut buf[($len + total_read_len)..])?;
 479                                         total_read_len += read_len;
 480                                 }
 481                                 if total_read_len == 0 || buf[$len] != 0 {
 482                                         let first_byte = $len - ($len - total_read_len);
 483                                         let mut bytes = [0; $len];
 484                                         bytes.copy_from_slice(&buf[first_byte..first_byte + $len]);
 485                                         Ok(HighZeroBytesDroppedBigSize(<$val_type>::from_be_bytes(bytes)))
 486                                 } else {
 487                                         // If the encoding had extra zero bytes, return a failure even though we know
 488                                         // what they meant (as the TLV test vectors require this)
 489                                         Err(DecodeError::InvalidValue)
 490                                 }
 491                         }
 492                 }
 493                 impl From<$val_type> for HighZeroBytesDroppedBigSize<$val_type> {
 494                         fn from(val: $val_type) -> Self { Self(val) }
 495                 }
 496         }
 497 }
 498
 499 impl_writeable_primitive!(u128, 16);
 500 impl_writeable_primitive!(u64, 8);
 501 impl_writeable_primitive!(u32, 4);
 502 impl_writeable_primitive!(u16, 2);
 503
 504 impl Writeable for u8 {
 505         #[inline]
 506         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 507                 writer.write_all(&[*self])
 508         }
 509 }
 510 impl Readable for u8 {
 511         #[inline]
 512         fn read<R: Read>(reader: &mut R) -> Result<u8, DecodeError> {
 513                 let mut buf = [0; 1];
 514                 reader.read_exact(&mut buf)?;
 515                 Ok(buf[0])
 516         }
 517 }
 518
 519 impl Writeable for bool {
 520         #[inline]
 521         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 522                 writer.write_all(&[if *self {1} else {0}])
 523         }
 524 }
 525 impl Readable for bool {
 526         #[inline]
 527         fn read<R: Read>(reader: &mut R) -> Result<bool, DecodeError> {
 528                 let mut buf = [0; 1];
 529                 reader.read_exact(&mut buf)?;
 530                 if buf[0] != 0 && buf[0] != 1 {
 531                         return Err(DecodeError::InvalidValue);
 532                 }
 533                 Ok(buf[0] == 1)
 534         }
 535 }
 536
 537 // u8 arrays
 538 macro_rules! impl_array {
 539         ( $size:expr ) => (
 540                 impl Writeable for [u8; $size]
 541                 {
 542                         #[inline]
 543                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 544                                 w.write_all(self)
 545                         }
 546                 }
 547
 548                 impl Readable for [u8; $size]
 549                 {
 550                         #[inline]
 551                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 552                                 let mut buf = [0u8; $size];
 553                                 r.read_exact(&mut buf)?;
 554                                 Ok(buf)
 555                         }
 556                 }
 557         );
 558 }
 559
 560 impl_array!(3); // for rgb, ISO 4712 code
 561 impl_array!(4); // for IPv4
 562 impl_array!(12); // for OnionV2
 563 impl_array!(16); // for IPv6
 564 impl_array!(32); // for channel id & hmac
 565 impl_array!(PUBLIC_KEY_SIZE); // for PublicKey
 566 impl_array!(64); // for ecdsa::Signature and schnorr::Signature
 567 impl_array!(1300); // for OnionPacket.hop_data
 568
 569 impl Writeable for [u16; 8] {
 570         #[inline]
 571         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 572                 for v in self.iter() {
 573                         w.write_all(&v.to_be_bytes())?
 574                 }
 575                 Ok(())
 576         }
 577 }
 578
 579 impl Readable for [u16; 8] {
 580         #[inline]
 581         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 582                 let mut buf = [0u8; 16];
 583                 r.read_exact(&mut buf)?;
 584                 let mut res = [0u16; 8];
 585                 for (idx, v) in res.iter_mut().enumerate() {
 586                         *v = (buf[idx] as u16) << 8 | (buf[idx + 1] as u16)
 587                 }
 588                 Ok(res)
 589         }
 590 }
 591
 592 /// A type for variable-length values within TLV record where the length is encoded as part of the record.
 593 /// Used to prevent encoding the length twice.
 594 pub struct WithoutLength<T>(pub T);
 595
 596 impl Writeable for WithoutLength<&String> {
 597         #[inline]
 598         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 599                 w.write_all(self.0.as_bytes())
 600         }
 601 }
 602 impl Readable for WithoutLength<String> {
 603         #[inline]
 604         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 605                 let v: WithoutLength<Vec<u8>> = Readable::read(r)?;
 606                 Ok(Self(String::from_utf8(v.0).map_err(|_| DecodeError::InvalidValue)?))
 607         }
 608 }
 609 impl<'a> From<&'a String> for WithoutLength<&'a String> {
 610         fn from(s: &'a String) -> Self { Self(s) }
 611 }
 612
 613 impl<'a, T: Writeable> Writeable for WithoutLength<&'a Vec<T>> {
 614         #[inline]
 615         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 616                 for ref v in self.0.iter() {
 617                         v.write(writer)?;
 618                 }
 619                 Ok(())
 620         }
 621 }
 622
 623 impl<T: MaybeReadable> Readable for WithoutLength<Vec<T>> {
 624         #[inline]
 625         fn read<R: Read>(mut reader: &mut R) -> Result<Self, DecodeError> {
 626                 let mut values = Vec::new();
 627                 loop {
 628                         let mut track_read = ReadTrackingReader::new(&mut reader);
 629                         match MaybeReadable::read(&mut track_read) {
 630                                 Ok(Some(v)) => { values.push(v); },
 631                                 Ok(None) => { },
 632                                 // If we failed to read any bytes at all, we reached the end of our TLV
 633                                 // stream and have simply exhausted all entries.
 634                                 Err(ref e) if e == &DecodeError::ShortRead && !track_read.have_read => break,
 635                                 Err(e) => return Err(e),
 636                         }
 637                 }
 638                 Ok(Self(values))
 639         }
 640 }
 641 impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 642         fn from(v: &'a Vec<T>) -> Self { Self(v) }
 643 }
 644
 645 #[derive(Debug)]
 646 pub(crate) struct Iterable<'a, I: Iterator<Item = &'a T> + Clone, T: 'a>(pub I);
 647
 648 impl<'a, I: Iterator<Item = &'a T> + Clone, T: 'a + Writeable> Writeable for Iterable<'a, I, T> {
 649         #[inline]
 650         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 651                 for ref v in self.0.clone() {
 652                         v.write(writer)?;
 653                 }
 654                 Ok(())
 655         }
 656 }
 657
 658 #[cfg(test)]
 659 impl<'a, I: Iterator<Item = &'a T> + Clone, T: 'a + PartialEq> PartialEq for Iterable<'a, I, T> {
 660         fn eq(&self, other: &Self) -> bool {
 661                 self.0.clone().collect::<Vec<_>>() == other.0.clone().collect::<Vec<_>>()
 662         }
 663 }
 664
 665 macro_rules! impl_for_map {
 666         ($ty: ident, $keybound: ident, $constr: expr) => {
 667                 impl<K, V> Writeable for $ty<K, V>
 668                         where K: Writeable + Eq + $keybound, V: Writeable
 669                 {
 670                         #[inline]
 671                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 672                                 CollectionLength(self.len() as u64).write(w)?;
 673                                 for (key, value) in self.iter() {
 674                                         key.write(w)?;
 675                                         value.write(w)?;
 676                                 }
 677                                 Ok(())
 678                         }
 679                 }
 680
 681                 impl<K, V> Readable for $ty<K, V>
 682                         where K: Readable + Eq + $keybound, V: MaybeReadable
 683                 {
 684                         #[inline]
 685                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 686                                 let len: CollectionLength = Readable::read(r)?;
 687                                 let mut ret = $constr(len.0 as usize);
 688                                 for _ in 0..len.0 {
 689                                         let k = K::read(r)?;
 690                                         let v_opt = V::read(r)?;
 691                                         if let Some(v) = v_opt {
 692                                                 if ret.insert(k, v).is_some() {
 693                                                         return Err(DecodeError::InvalidValue);
 694                                                 }
 695                                         }
 696                                 }
 697                                 Ok(ret)
 698                         }
 699                 }
 700         }
 701 }
 702
 703 impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
 704 impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
 705
 706 // HashSet
 707 impl<T> Writeable for HashSet<T>
 708 where T: Writeable + Eq + Hash
 709 {
 710         #[inline]
 711         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 712                 CollectionLength(self.len() as u64).write(w)?;
 713                 for item in self.iter() {
 714                         item.write(w)?;
 715                 }
 716                 Ok(())
 717         }
 718 }
 719
 720 impl<T> Readable for HashSet<T>
 721 where T: Readable + Eq + Hash
 722 {
 723         #[inline]
 724         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 725                 let len: CollectionLength = Readable::read(r)?;
 726                 let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
 727                 for _ in 0..len.0 {
 728                         if !ret.insert(T::read(r)?) {
 729                                 return Err(DecodeError::InvalidValue)
 730                         }
 731                 }
 732                 Ok(ret)
 733         }
 734 }
 735
 736 // Vectors
 737 macro_rules! impl_for_vec {
 738         ($ty: ty $(, $name: ident)*) => {
 739                 impl<$($name : Writeable),*> Writeable for Vec<$ty> {
 740                         #[inline]
 741                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 742                                 CollectionLength(self.len() as u64).write(w)?;
 743                                 for elem in self.iter() {
 744                                         elem.write(w)?;
 745                                 }
 746                                 Ok(())
 747                         }
 748                 }
 749
 750                 impl<$($name : Readable),*> Readable for Vec<$ty> {
 751                         #[inline]
 752                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 753                                 let len: CollectionLength = Readable::read(r)?;
 754                                 let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
 755                                 for _ in 0..len.0 {
 756                                         if let Some(val) = MaybeReadable::read(r)? {
 757                                                 ret.push(val);
 758                                         }
 759                                 }
 760                                 Ok(ret)
 761                         }
 762                 }
 763         }
 764 }
 765
 766 impl Writeable for Vec<u8> {
 767         #[inline]
 768         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 769                 CollectionLength(self.len() as u64).write(w)?;
 770                 w.write_all(&self)
 771         }
 772 }
 773
 774 impl Readable for Vec<u8> {
 775         #[inline]
 776         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 777                 let mut len: CollectionLength = Readable::read(r)?;
 778                 let mut ret = Vec::new();
 779                 while len.0 > 0 {
 780                         let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
 781                         let readstart = ret.len();
 782                         ret.resize(readstart + readamt, 0);
 783                         r.read_exact(&mut ret[readstart..])?;
 784                         len.0 -= readamt as u64;
 785                 }
 786                 Ok(ret)
 787         }
 788 }
 789
 790 impl_for_vec!(ecdsa::Signature);
 791 impl_for_vec!(crate::ln::channelmanager::MonitorUpdateCompletionAction);
 792 impl_for_vec!((A, B), A, B);
 793
 794 impl Writeable for Script {
 795         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 796                 (self.len() as u16).write(w)?;
 797                 w.write_all(self.as_bytes())
 798         }
 799 }
 800
 801 impl Readable for Script {
 802         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 803                 let len = <u16 as Readable>::read(r)? as usize;
 804                 let mut buf = vec![0; len];
 805                 r.read_exact(&mut buf)?;
 806                 Ok(Script::from(buf))
 807         }
 808 }
 809
 810 impl Writeable for PublicKey {
 811         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 812                 self.serialize().write(w)
 813         }
 814         #[inline]
 815         fn serialized_length(&self) -> usize {
 816                 PUBLIC_KEY_SIZE
 817         }
 818 }
 819
 820 impl Readable for PublicKey {
 821         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 822                 let buf: [u8; PUBLIC_KEY_SIZE] = Readable::read(r)?;
 823                 match PublicKey::from_slice(&buf) {
 824                         Ok(key) => Ok(key),
 825                         Err(_) => return Err(DecodeError::InvalidValue),
 826                 }
 827         }
 828 }
 829
 830 impl Writeable for SecretKey {
 831         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 832                 let mut ser = [0; SECRET_KEY_SIZE];
 833                 ser.copy_from_slice(&self[..]);
 834                 ser.write(w)
 835         }
 836         #[inline]
 837         fn serialized_length(&self) -> usize {
 838                 SECRET_KEY_SIZE
 839         }
 840 }
 841
 842 impl Readable for SecretKey {
 843         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 844                 let buf: [u8; SECRET_KEY_SIZE] = Readable::read(r)?;
 845                 match SecretKey::from_slice(&buf) {
 846                         Ok(key) => Ok(key),
 847                         Err(_) => return Err(DecodeError::InvalidValue),
 848                 }
 849         }
 850 }
 851
 852 impl Writeable for Sha256dHash {
 853         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 854                 w.write_all(&self[..])
 855         }
 856 }
 857
 858 impl Readable for Sha256dHash {
 859         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 860                 use bitcoin::hashes::Hash;
 861
 862                 let buf: [u8; 32] = Readable::read(r)?;
 863                 Ok(Sha256dHash::from_slice(&buf[..]).unwrap())
 864         }
 865 }
 866
 867 impl Writeable for ecdsa::Signature {
 868         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 869                 self.serialize_compact().write(w)
 870         }
 871 }
 872
 873 impl Readable for ecdsa::Signature {
 874         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 875                 let buf: [u8; COMPACT_SIGNATURE_SIZE] = Readable::read(r)?;
 876                 match ecdsa::Signature::from_compact(&buf) {
 877                         Ok(sig) => Ok(sig),
 878                         Err(_) => return Err(DecodeError::InvalidValue),
 879                 }
 880         }
 881 }
 882
 883 impl Writeable for schnorr::Signature {
 884         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 885                 self.as_ref().write(w)
 886         }
 887 }
 888
 889 impl Readable for schnorr::Signature {
 890         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 891                 let buf: [u8; SCHNORR_SIGNATURE_SIZE] = Readable::read(r)?;
 892                 match schnorr::Signature::from_slice(&buf) {
 893                         Ok(sig) => Ok(sig),
 894                         Err(_) => return Err(DecodeError::InvalidValue),
 895                 }
 896         }
 897 }
 898
 899 impl Writeable for PaymentPreimage {
 900         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 901                 self.0.write(w)
 902         }
 903 }
 904
 905 impl Readable for PaymentPreimage {
 906         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 907                 let buf: [u8; 32] = Readable::read(r)?;
 908                 Ok(PaymentPreimage(buf))
 909         }
 910 }
 911
 912 impl Writeable for PaymentHash {
 913         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 914                 self.0.write(w)
 915         }
 916 }
 917
 918 impl Readable for PaymentHash {
 919         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 920                 let buf: [u8; 32] = Readable::read(r)?;
 921                 Ok(PaymentHash(buf))
 922         }
 923 }
 924
 925 impl Writeable for PaymentSecret {
 926         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 927                 self.0.write(w)
 928         }
 929 }
 930
 931 impl Readable for PaymentSecret {
 932         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 933                 let buf: [u8; 32] = Readable::read(r)?;
 934                 Ok(PaymentSecret(buf))
 935         }
 936 }
 937
 938 impl<T: Writeable> Writeable for Box<T> {
 939         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 940                 T::write(&**self, w)
 941         }
 942 }
 943
 944 impl<T: Readable> Readable for Box<T> {
 945         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 946                 Ok(Box::new(Readable::read(r)?))
 947         }
 948 }
 949
 950 impl<T: Writeable> Writeable for Option<T> {
 951         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 952                 match *self {
 953                         None => 0u8.write(w)?,
 954                         Some(ref data) => {
 955                                 BigSize(data.serialized_length() as u64 + 1).write(w)?;
 956                                 data.write(w)?;
 957                         }
 958                 }
 959                 Ok(())
 960         }
 961 }
 962
 963 impl<T: Readable> Readable for Option<T>
 964 {
 965         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 966                 let len: BigSize = Readable::read(r)?;
 967                 match len.0 {
 968                         0 => Ok(None),
 969                         len => {
 970                                 let mut reader = FixedLengthReader::new(r, len - 1);
 971                                 Ok(Some(Readable::read(&mut reader)?))
 972                         }
 973                 }
 974         }
 975 }
 976
 977 impl Writeable for Txid {
 978         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 979                 w.write_all(&self[..])
 980         }
 981 }
 982
 983 impl Readable for Txid {
 984         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 985                 use bitcoin::hashes::Hash;
 986
 987                 let buf: [u8; 32] = Readable::read(r)?;
 988                 Ok(Txid::from_slice(&buf[..]).unwrap())
 989         }
 990 }
 991
 992 impl Writeable for BlockHash {
 993         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 994                 w.write_all(&self[..])
 995         }
 996 }
 997
 998 impl Readable for BlockHash {
 999         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1000                 use bitcoin::hashes::Hash;
1001
1002                 let buf: [u8; 32] = Readable::read(r)?;
1003                 Ok(BlockHash::from_slice(&buf[..]).unwrap())
1004         }
1005 }
1006
1007 impl Writeable for ChainHash {
1008         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1009                 w.write_all(self.as_bytes())
1010         }
1011 }
1012
1013 impl Readable for ChainHash {
1014         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1015                 let buf: [u8; 32] = Readable::read(r)?;
1016                 Ok(ChainHash::from(&buf[..]))
1017         }
1018 }
1019
1020 impl Writeable for OutPoint {
1021         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1022                 self.txid.write(w)?;
1023                 self.vout.write(w)?;
1024                 Ok(())
1025         }
1026 }
1027
1028 impl Readable for OutPoint {
1029         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1030                 let txid = Readable::read(r)?;
1031                 let vout = Readable::read(r)?;
1032                 Ok(OutPoint {
1033                         txid,
1034                         vout,
1035                 })
1036         }
1037 }
1038
1039 macro_rules! impl_consensus_ser {
1040         ($bitcoin_type: ty) => {
1041                 impl Writeable for $bitcoin_type {
1042                         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
1043                                 match self.consensus_encode(&mut WriterWriteAdaptor(writer)) {
1044                                         Ok(_) => Ok(()),
1045                                         Err(e) => Err(e),
1046                                 }
1047                         }
1048                 }
1049
1050                 impl Readable for $bitcoin_type {
1051                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1052                                 match consensus::encode::Decodable::consensus_decode(r) {
1053                                         Ok(t) => Ok(t),
1054                                         Err(consensus::encode::Error::Io(ref e)) if e.kind() == io::ErrorKind::UnexpectedEof => Err(DecodeError::ShortRead),
1055                                         Err(consensus::encode::Error::Io(e)) => Err(DecodeError::Io(e.kind())),
1056                                         Err(_) => Err(DecodeError::InvalidValue),
1057                                 }
1058                         }
1059                 }
1060         }
1061 }
1062 impl_consensus_ser!(Transaction);
1063 impl_consensus_ser!(TxOut);
1064
1065 impl<T: Readable> Readable for Mutex<T> {
1066         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1067                 let t: T = Readable::read(r)?;
1068                 Ok(Mutex::new(t))
1069         }
1070 }
1071 impl<T: Writeable> Writeable for Mutex<T> {
1072         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1073                 self.lock().unwrap().write(w)
1074         }
1075 }
1076
1077 impl<A: Readable, B: Readable> Readable for (A, B) {
1078         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1079                 let a: A = Readable::read(r)?;
1080                 let b: B = Readable::read(r)?;
1081                 Ok((a, b))
1082         }
1083 }
1084 impl<A: Writeable, B: Writeable> Writeable for (A, B) {
1085         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1086                 self.0.write(w)?;
1087                 self.1.write(w)
1088         }
1089 }
1090
1091 impl<A: Readable, B: Readable, C: Readable> Readable for (A, B, C) {
1092         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1093                 let a: A = Readable::read(r)?;
1094                 let b: B = Readable::read(r)?;
1095                 let c: C = Readable::read(r)?;
1096                 Ok((a, b, c))
1097         }
1098 }
1099 impl<A: Writeable, B: Writeable, C: Writeable> Writeable for (A, B, C) {
1100         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1101                 self.0.write(w)?;
1102                 self.1.write(w)?;
1103                 self.2.write(w)
1104         }
1105 }
1106
1107 impl<A: Readable, B: Readable, C: Readable, D: Readable> Readable for (A, B, C, D) {
1108         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1109                 let a: A = Readable::read(r)?;
1110                 let b: B = Readable::read(r)?;
1111                 let c: C = Readable::read(r)?;
1112                 let d: D = Readable::read(r)?;
1113                 Ok((a, b, c, d))
1114         }
1115 }
1116 impl<A: Writeable, B: Writeable, C: Writeable, D: Writeable> Writeable for (A, B, C, D) {
1117         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1118                 self.0.write(w)?;
1119                 self.1.write(w)?;
1120                 self.2.write(w)?;
1121                 self.3.write(w)
1122         }
1123 }
1124
1125 impl Writeable for () {
1126         fn write<W: Writer>(&self, _: &mut W) -> Result<(), io::Error> {
1127                 Ok(())
1128         }
1129 }
1130 impl Readable for () {
1131         fn read<R: Read>(_r: &mut R) -> Result<Self, DecodeError> {
1132                 Ok(())
1133         }
1134 }
1135
1136 impl Writeable for String {
1137         #[inline]
1138         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1139                 CollectionLength(self.len() as u64).write(w)?;
1140                 w.write_all(self.as_bytes())
1141         }
1142 }
1143 impl Readable for String {
1144         #[inline]
1145         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1146                 let v: Vec<u8> = Readable::read(r)?;
1147                 let ret = String::from_utf8(v).map_err(|_| DecodeError::InvalidValue)?;
1148                 Ok(ret)
1149         }
1150 }
1151
1152 /// Represents a hostname for serialization purposes.
1153 /// Only the character set and length will be validated.
1154 /// The character set consists of ASCII alphanumeric characters, hyphens, and periods.
1155 /// Its length is guaranteed to be representable by a single byte.
1156 /// This serialization is used by [`BOLT 7`] hostnames.
1157 ///
1158 /// [`BOLT 7`]: https://github.com/lightning/bolts/blob/master/07-routing-gossip.md
1159 #[derive(Clone, Debug, PartialEq, Eq)]
1160 pub struct Hostname(String);
1161 impl Hostname {
1162         /// Returns the length of the hostname.
1163         pub fn len(&self) -> u8 {
1164                 (&self.0).len() as u8
1165         }
1166 }
1167 impl Deref for Hostname {
1168         type Target = String;
1169
1170         fn deref(&self) -> &Self::Target {
1171                 &self.0
1172         }
1173 }
1174 impl From<Hostname> for String {
1175         fn from(hostname: Hostname) -> Self {
1176                 hostname.0
1177         }
1178 }
1179 impl TryFrom<Vec<u8>> for Hostname {
1180         type Error = ();
1181
1182         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
1183                 if let Ok(s) = String::from_utf8(bytes) {
1184                         Hostname::try_from(s)
1185                 } else {
1186                         Err(())
1187                 }
1188         }
1189 }
1190 impl TryFrom<String> for Hostname {
1191         type Error = ();
1192
1193         fn try_from(s: String) -> Result<Self, Self::Error> {
1194                 if s.len() <= 255 && s.chars().all(|c|
1195                         c.is_ascii_alphanumeric() ||
1196                         c == '.' ||
1197                         c == '-'
1198                 ) {
1199                         Ok(Hostname(s))
1200                 } else {
1201                         Err(())
1202                 }
1203         }
1204 }
1205 impl Writeable for Hostname {
1206         #[inline]
1207         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1208                 self.len().write(w)?;
1209                 w.write_all(self.as_bytes())
1210         }
1211 }
1212 impl Readable for Hostname {
1213         #[inline]
1214         fn read<R: Read>(r: &mut R) -> Result<Hostname, DecodeError> {
1215                 let len: u8 = Readable::read(r)?;
1216                 let mut vec = Vec::with_capacity(len.into());
1217                 vec.resize(len.into(), 0);
1218                 r.read_exact(&mut vec)?;
1219                 Hostname::try_from(vec).map_err(|_| DecodeError::InvalidValue)
1220         }
1221 }
1222
1223 impl Writeable for Duration {
1224         #[inline]
1225         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1226                 self.as_secs().write(w)?;
1227                 self.subsec_nanos().write(w)
1228         }
1229 }
1230 impl Readable for Duration {
1231         #[inline]
1232         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1233                 let secs = Readable::read(r)?;
1234                 let nanos = Readable::read(r)?;
1235                 Ok(Duration::new(secs, nanos))
1236         }
1237 }
1238
1239 #[cfg(test)]
1240 mod tests {
1241         use core::convert::TryFrom;
1242         use crate::util::ser::{Readable, Hostname, Writeable};
1243
1244         #[test]
1245         fn hostname_conversion() {
1246                 assert_eq!(Hostname::try_from(String::from("a-test.com")).unwrap().as_str(), "a-test.com");
1247
1248                 assert!(Hostname::try_from(String::from("\"")).is_err());
1249                 assert!(Hostname::try_from(String::from("$")).is_err());
1250                 assert!(Hostname::try_from(String::from("⚡")).is_err());
1251                 let mut large_vec = Vec::with_capacity(256);
1252                 large_vec.resize(256, b'A');
1253                 assert!(Hostname::try_from(String::from_utf8(large_vec).unwrap()).is_err());
1254         }
1255
1256         #[test]
1257         fn hostname_serialization() {
1258                 let hostname = Hostname::try_from(String::from("test")).unwrap();
1259                 let mut buf: Vec<u8> = Vec::new();
1260                 hostname.write(&mut buf).unwrap();
1261                 assert_eq!(Hostname::read(&mut buf.as_slice()).unwrap().as_str(), "test");
1262         }
1263 }