_ 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 OptionDeserWrapper<T: Readable>(pub Option<T>);
 293 impl<T: Readable> Readable for OptionDeserWrapper<T> {
 294         #[inline]
 295         fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
 296                 Ok(Self(Some(Readable::read(reader)?)))
 297         }
 298 }
 299 /// When handling `default_values`, we want to map the default-value T directly
 300 /// to a `OptionDeserWrapper<T>` in a way that works for `field: T = t;` as
 301 /// well. Thus, we assume `Into<T> for T` does nothing and use that.
 302 impl<T: Readable> From<T> for OptionDeserWrapper<T> {
 303         fn from(t: T) -> OptionDeserWrapper<T> { OptionDeserWrapper(Some(t)) }
 304 }
 305
 306 pub(crate) struct U48(pub u64);
 307 impl Writeable for U48 {
 308         #[inline]
 309         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 310                 writer.write_all(&be48_to_array(self.0))
 311         }
 312 }
 313 impl Readable for U48 {
 314         #[inline]
 315         fn read<R: Read>(reader: &mut R) -> Result<U48, DecodeError> {
 316                 let mut buf = [0; 6];
 317                 reader.read_exact(&mut buf)?;
 318                 Ok(U48(slice_to_be48(&buf)))
 319         }
 320 }
 321
 322 /// Lightning TLV uses a custom variable-length integer called `BigSize`. It is similar to Bitcoin's
 323 /// variable-length integers except that it is serialized in big-endian instead of little-endian.
 324 ///
 325 /// Like Bitcoin's variable-length integer, it exhibits ambiguity in that certain values can be
 326 /// encoded in several different ways, which we must check for at deserialization-time. Thus, if
 327 /// you're looking for an example of a variable-length integer to use for your own project, move
 328 /// along, this is a rather poor design.
 329 pub struct BigSize(pub u64);
 330 impl Writeable for BigSize {
 331         #[inline]
 332         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 333                 match self.0 {
 334                         0...0xFC => {
 335                                 (self.0 as u8).write(writer)
 336                         },
 337                         0xFD...0xFFFF => {
 338                                 0xFDu8.write(writer)?;
 339                                 (self.0 as u16).write(writer)
 340                         },
 341                         0x10000...0xFFFFFFFF => {
 342                                 0xFEu8.write(writer)?;
 343                                 (self.0 as u32).write(writer)
 344                         },
 345                         _ => {
 346                                 0xFFu8.write(writer)?;
 347                                 (self.0 as u64).write(writer)
 348                         },
 349                 }
 350         }
 351 }
 352 impl Readable for BigSize {
 353         #[inline]
 354         fn read<R: Read>(reader: &mut R) -> Result<BigSize, DecodeError> {
 355                 let n: u8 = Readable::read(reader)?;
 356                 match n {
 357                         0xFF => {
 358                                 let x: u64 = Readable::read(reader)?;
 359                                 if x < 0x100000000 {
 360                                         Err(DecodeError::InvalidValue)
 361                                 } else {
 362                                         Ok(BigSize(x))
 363                                 }
 364                         }
 365                         0xFE => {
 366                                 let x: u32 = Readable::read(reader)?;
 367                                 if x < 0x10000 {
 368                                         Err(DecodeError::InvalidValue)
 369                                 } else {
 370                                         Ok(BigSize(x as u64))
 371                                 }
 372                         }
 373                         0xFD => {
 374                                 let x: u16 = Readable::read(reader)?;
 375                                 if x < 0xFD {
 376                                         Err(DecodeError::InvalidValue)
 377                                 } else {
 378                                         Ok(BigSize(x as u64))
 379                                 }
 380                         }
 381                         n => Ok(BigSize(n as u64))
 382                 }
 383         }
 384 }
 385
 386 /// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
 387 /// primarily targets that, we must as well. However, because we may serialize objects that have
 388 /// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
 389 /// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
 390 /// "read eight more bytes".
 391 ///
 392 /// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
 393 /// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
 394 /// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
 395 struct CollectionLength(pub u64);
 396 impl Writeable for CollectionLength {
 397         #[inline]
 398         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 399                 if self.0 < 0xffff {
 400                         (self.0 as u16).write(writer)
 401                 } else {
 402                         0xffffu16.write(writer)?;
 403                         (self.0 - 0xffff).write(writer)
 404                 }
 405         }
 406 }
 407
 408 impl Readable for CollectionLength {
 409         #[inline]
 410         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 411                 let mut val: u64 = <u16 as Readable>::read(r)? as u64;
 412                 if val == 0xffff {
 413                         val = <u64 as Readable>::read(r)?
 414                                 .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
 415                 }
 416                 Ok(CollectionLength(val))
 417         }
 418 }
 419
 420 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 421 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 422 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
 423 #[cfg_attr(test, derive(PartialEq, Eq, Debug))]
 424 pub(crate) struct HighZeroBytesDroppedBigSize<T>(pub T);
 425
 426 macro_rules! impl_writeable_primitive {
 427         ($val_type:ty, $len: expr) => {
 428                 impl Writeable for $val_type {
 429                         #[inline]
 430                         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 431                                 writer.write_all(&self.to_be_bytes())
 432                         }
 433                 }
 434                 impl Writeable for HighZeroBytesDroppedBigSize<$val_type> {
 435                         #[inline]
 436                         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 437                                 // Skip any full leading 0 bytes when writing (in BE):
 438                                 writer.write_all(&self.0.to_be_bytes()[(self.0.leading_zeros()/8) as usize..$len])
 439                         }
 440                 }
 441                 impl Readable for $val_type {
 442                         #[inline]
 443                         fn read<R: Read>(reader: &mut R) -> Result<$val_type, DecodeError> {
 444                                 let mut buf = [0; $len];
 445                                 reader.read_exact(&mut buf)?;
 446                                 Ok(<$val_type>::from_be_bytes(buf))
 447                         }
 448                 }
 449                 impl Readable for HighZeroBytesDroppedBigSize<$val_type> {
 450                         #[inline]
 451                         fn read<R: Read>(reader: &mut R) -> Result<HighZeroBytesDroppedBigSize<$val_type>, DecodeError> {
 452                                 // We need to accept short reads (read_len == 0) as "EOF" and handle them as simply
 453                                 // the high bytes being dropped. To do so, we start reading into the middle of buf
 454                                 // and then convert the appropriate number of bytes with extra high bytes out of
 455                                 // buf.
 456                                 let mut buf = [0; $len*2];
 457                                 let mut read_len = reader.read(&mut buf[$len..])?;
 458                                 let mut total_read_len = read_len;
 459                                 while read_len != 0 && total_read_len != $len {
 460                                         read_len = reader.read(&mut buf[($len + total_read_len)..])?;
 461                                         total_read_len += read_len;
 462                                 }
 463                                 if total_read_len == 0 || buf[$len] != 0 {
 464                                         let first_byte = $len - ($len - total_read_len);
 465                                         let mut bytes = [0; $len];
 466                                         bytes.copy_from_slice(&buf[first_byte..first_byte + $len]);
 467                                         Ok(HighZeroBytesDroppedBigSize(<$val_type>::from_be_bytes(bytes)))
 468                                 } else {
 469                                         // If the encoding had extra zero bytes, return a failure even though we know
 470                                         // what they meant (as the TLV test vectors require this)
 471                                         Err(DecodeError::InvalidValue)
 472                                 }
 473                         }
 474                 }
 475                 impl From<$val_type> for HighZeroBytesDroppedBigSize<$val_type> {
 476                         fn from(val: $val_type) -> Self { Self(val) }
 477                 }
 478         }
 479 }
 480
 481 impl_writeable_primitive!(u128, 16);
 482 impl_writeable_primitive!(u64, 8);
 483 impl_writeable_primitive!(u32, 4);
 484 impl_writeable_primitive!(u16, 2);
 485
 486 impl Writeable for u8 {
 487         #[inline]
 488         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 489                 writer.write_all(&[*self])
 490         }
 491 }
 492 impl Readable for u8 {
 493         #[inline]
 494         fn read<R: Read>(reader: &mut R) -> Result<u8, DecodeError> {
 495                 let mut buf = [0; 1];
 496                 reader.read_exact(&mut buf)?;
 497                 Ok(buf[0])
 498         }
 499 }
 500
 501 impl Writeable for bool {
 502         #[inline]
 503         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 504                 writer.write_all(&[if *self {1} else {0}])
 505         }
 506 }
 507 impl Readable for bool {
 508         #[inline]
 509         fn read<R: Read>(reader: &mut R) -> Result<bool, DecodeError> {
 510                 let mut buf = [0; 1];
 511                 reader.read_exact(&mut buf)?;
 512                 if buf[0] != 0 && buf[0] != 1 {
 513                         return Err(DecodeError::InvalidValue);
 514                 }
 515                 Ok(buf[0] == 1)
 516         }
 517 }
 518
 519 // u8 arrays
 520 macro_rules! impl_array {
 521         ( $size:expr ) => (
 522                 impl Writeable for [u8; $size]
 523                 {
 524                         #[inline]
 525                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 526                                 w.write_all(self)
 527                         }
 528                 }
 529
 530                 impl Readable for [u8; $size]
 531                 {
 532                         #[inline]
 533                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 534                                 let mut buf = [0u8; $size];
 535                                 r.read_exact(&mut buf)?;
 536                                 Ok(buf)
 537                         }
 538                 }
 539         );
 540 }
 541
 542 impl_array!(3); // for rgb, ISO 4712 code
 543 impl_array!(4); // for IPv4
 544 impl_array!(12); // for OnionV2
 545 impl_array!(16); // for IPv6
 546 impl_array!(32); // for channel id & hmac
 547 impl_array!(PUBLIC_KEY_SIZE); // for PublicKey
 548 impl_array!(64); // for ecdsa::Signature and schnorr::Signature
 549 impl_array!(1300); // for OnionPacket.hop_data
 550
 551 impl Writeable for [u16; 8] {
 552         #[inline]
 553         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 554                 for v in self.iter() {
 555                         w.write_all(&v.to_be_bytes())?
 556                 }
 557                 Ok(())
 558         }
 559 }
 560
 561 impl Readable for [u16; 8] {
 562         #[inline]
 563         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 564                 let mut buf = [0u8; 16];
 565                 r.read_exact(&mut buf)?;
 566                 let mut res = [0u16; 8];
 567                 for (idx, v) in res.iter_mut().enumerate() {
 568                         *v = (buf[idx] as u16) << 8 | (buf[idx + 1] as u16)
 569                 }
 570                 Ok(res)
 571         }
 572 }
 573
 574 /// A type for variable-length values within TLV record where the length is encoded as part of the record.
 575 /// Used to prevent encoding the length twice.
 576 pub struct WithoutLength<T>(pub T);
 577
 578 impl Writeable for WithoutLength<&String> {
 579         #[inline]
 580         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 581                 w.write_all(self.0.as_bytes())
 582         }
 583 }
 584 impl Readable for WithoutLength<String> {
 585         #[inline]
 586         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 587                 let v: WithoutLength<Vec<u8>> = Readable::read(r)?;
 588                 Ok(Self(String::from_utf8(v.0).map_err(|_| DecodeError::InvalidValue)?))
 589         }
 590 }
 591 impl<'a> From<&'a String> for WithoutLength<&'a String> {
 592         fn from(s: &'a String) -> Self { Self(s) }
 593 }
 594
 595 impl<'a, T: Writeable> Writeable for WithoutLength<&'a Vec<T>> {
 596         #[inline]
 597         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 598                 for ref v in self.0.iter() {
 599                         v.write(writer)?;
 600                 }
 601                 Ok(())
 602         }
 603 }
 604
 605 impl<T: MaybeReadable> Readable for WithoutLength<Vec<T>> {
 606         #[inline]
 607         fn read<R: Read>(mut reader: &mut R) -> Result<Self, DecodeError> {
 608                 let mut values = Vec::new();
 609                 loop {
 610                         let mut track_read = ReadTrackingReader::new(&mut reader);
 611                         match MaybeReadable::read(&mut track_read) {
 612                                 Ok(Some(v)) => { values.push(v); },
 613                                 Ok(None) => { },
 614                                 // If we failed to read any bytes at all, we reached the end of our TLV
 615                                 // stream and have simply exhausted all entries.
 616                                 Err(ref e) if e == &DecodeError::ShortRead && !track_read.have_read => break,
 617                                 Err(e) => return Err(e),
 618                         }
 619                 }
 620                 Ok(Self(values))
 621         }
 622 }
 623 impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 624         fn from(v: &'a Vec<T>) -> Self { Self(v) }
 625 }
 626
 627 #[derive(Debug)]
 628 pub(crate) struct Iterable<'a, I: Iterator<Item = &'a T> + Clone, T: 'a>(pub I);
 629
 630 impl<'a, I: Iterator<Item = &'a T> + Clone, T: 'a + Writeable> Writeable for Iterable<'a, I, T> {
 631         #[inline]
 632         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 633                 for ref v in self.0.clone() {
 634                         v.write(writer)?;
 635                 }
 636                 Ok(())
 637         }
 638 }
 639
 640 #[cfg(test)]
 641 impl<'a, I: Iterator<Item = &'a T> + Clone, T: 'a + PartialEq> PartialEq for Iterable<'a, I, T> {
 642         fn eq(&self, other: &Self) -> bool {
 643                 self.0.clone().collect::<Vec<_>>() == other.0.clone().collect::<Vec<_>>()
 644         }
 645 }
 646
 647 macro_rules! impl_for_map {
 648         ($ty: ident, $keybound: ident, $constr: expr) => {
 649                 impl<K, V> Writeable for $ty<K, V>
 650                         where K: Writeable + Eq + $keybound, V: Writeable
 651                 {
 652                         #[inline]
 653                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 654                                 CollectionLength(self.len() as u64).write(w)?;
 655                                 for (key, value) in self.iter() {
 656                                         key.write(w)?;
 657                                         value.write(w)?;
 658                                 }
 659                                 Ok(())
 660                         }
 661                 }
 662
 663                 impl<K, V> Readable for $ty<K, V>
 664                         where K: Readable + Eq + $keybound, V: MaybeReadable
 665                 {
 666                         #[inline]
 667                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 668                                 let len: CollectionLength = Readable::read(r)?;
 669                                 let mut ret = $constr(len.0 as usize);
 670                                 for _ in 0..len.0 {
 671                                         let k = K::read(r)?;
 672                                         let v_opt = V::read(r)?;
 673                                         if let Some(v) = v_opt {
 674                                                 if ret.insert(k, v).is_some() {
 675                                                         return Err(DecodeError::InvalidValue);
 676                                                 }
 677                                         }
 678                                 }
 679                                 Ok(ret)
 680                         }
 681                 }
 682         }
 683 }
 684
 685 impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
 686 impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
 687
 688 // HashSet
 689 impl<T> Writeable for HashSet<T>
 690 where T: Writeable + Eq + Hash
 691 {
 692         #[inline]
 693         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 694                 CollectionLength(self.len() as u64).write(w)?;
 695                 for item in self.iter() {
 696                         item.write(w)?;
 697                 }
 698                 Ok(())
 699         }
 700 }
 701
 702 impl<T> Readable for HashSet<T>
 703 where T: Readable + Eq + Hash
 704 {
 705         #[inline]
 706         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 707                 let len: CollectionLength = Readable::read(r)?;
 708                 let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
 709                 for _ in 0..len.0 {
 710                         if !ret.insert(T::read(r)?) {
 711                                 return Err(DecodeError::InvalidValue)
 712                         }
 713                 }
 714                 Ok(ret)
 715         }
 716 }
 717
 718 // Vectors
 719 macro_rules! impl_for_vec {
 720         ($ty: ty $(, $name: ident)*) => {
 721                 impl<$($name : Writeable),*> Writeable for Vec<$ty> {
 722                         #[inline]
 723                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 724                                 CollectionLength(self.len() as u64).write(w)?;
 725                                 for elem in self.iter() {
 726                                         elem.write(w)?;
 727                                 }
 728                                 Ok(())
 729                         }
 730                 }
 731
 732                 impl<$($name : Readable),*> Readable for Vec<$ty> {
 733                         #[inline]
 734                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 735                                 let len: CollectionLength = Readable::read(r)?;
 736                                 let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
 737                                 for _ in 0..len.0 {
 738                                         if let Some(val) = MaybeReadable::read(r)? {
 739                                                 ret.push(val);
 740                                         }
 741                                 }
 742                                 Ok(ret)
 743                         }
 744                 }
 745         }
 746 }
 747
 748 impl Writeable for Vec<u8> {
 749         #[inline]
 750         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 751                 CollectionLength(self.len() as u64).write(w)?;
 752                 w.write_all(&self)
 753         }
 754 }
 755
 756 impl Readable for Vec<u8> {
 757         #[inline]
 758         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 759                 let mut len: CollectionLength = Readable::read(r)?;
 760                 let mut ret = Vec::new();
 761                 while len.0 > 0 {
 762                         let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
 763                         let readstart = ret.len();
 764                         ret.resize(readstart + readamt, 0);
 765                         r.read_exact(&mut ret[readstart..])?;
 766                         len.0 -= readamt as u64;
 767                 }
 768                 Ok(ret)
 769         }
 770 }
 771
 772 impl_for_vec!(ecdsa::Signature);
 773 impl_for_vec!(crate::ln::channelmanager::MonitorUpdateCompletionAction);
 774 impl_for_vec!((A, B), A, B);
 775
 776 impl Writeable for Script {
 777         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 778                 (self.len() as u16).write(w)?;
 779                 w.write_all(self.as_bytes())
 780         }
 781 }
 782
 783 impl Readable for Script {
 784         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 785                 let len = <u16 as Readable>::read(r)? as usize;
 786                 let mut buf = vec![0; len];
 787                 r.read_exact(&mut buf)?;
 788                 Ok(Script::from(buf))
 789         }
 790 }
 791
 792 impl Writeable for PublicKey {
 793         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 794                 self.serialize().write(w)
 795         }
 796         #[inline]
 797         fn serialized_length(&self) -> usize {
 798                 PUBLIC_KEY_SIZE
 799         }
 800 }
 801
 802 impl Readable for PublicKey {
 803         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 804                 let buf: [u8; PUBLIC_KEY_SIZE] = Readable::read(r)?;
 805                 match PublicKey::from_slice(&buf) {
 806                         Ok(key) => Ok(key),
 807                         Err(_) => return Err(DecodeError::InvalidValue),
 808                 }
 809         }
 810 }
 811
 812 impl Writeable for SecretKey {
 813         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 814                 let mut ser = [0; SECRET_KEY_SIZE];
 815                 ser.copy_from_slice(&self[..]);
 816                 ser.write(w)
 817         }
 818         #[inline]
 819         fn serialized_length(&self) -> usize {
 820                 SECRET_KEY_SIZE
 821         }
 822 }
 823
 824 impl Readable for SecretKey {
 825         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 826                 let buf: [u8; SECRET_KEY_SIZE] = Readable::read(r)?;
 827                 match SecretKey::from_slice(&buf) {
 828                         Ok(key) => Ok(key),
 829                         Err(_) => return Err(DecodeError::InvalidValue),
 830                 }
 831         }
 832 }
 833
 834 impl Writeable for Sha256dHash {
 835         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 836                 w.write_all(&self[..])
 837         }
 838 }
 839
 840 impl Readable for Sha256dHash {
 841         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 842                 use bitcoin::hashes::Hash;
 843
 844                 let buf: [u8; 32] = Readable::read(r)?;
 845                 Ok(Sha256dHash::from_slice(&buf[..]).unwrap())
 846         }
 847 }
 848
 849 impl Writeable for ecdsa::Signature {
 850         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 851                 self.serialize_compact().write(w)
 852         }
 853 }
 854
 855 impl Readable for ecdsa::Signature {
 856         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 857                 let buf: [u8; COMPACT_SIGNATURE_SIZE] = Readable::read(r)?;
 858                 match ecdsa::Signature::from_compact(&buf) {
 859                         Ok(sig) => Ok(sig),
 860                         Err(_) => return Err(DecodeError::InvalidValue),
 861                 }
 862         }
 863 }
 864
 865 impl Writeable for schnorr::Signature {
 866         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 867                 self.as_ref().write(w)
 868         }
 869 }
 870
 871 impl Readable for schnorr::Signature {
 872         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 873                 let buf: [u8; SCHNORR_SIGNATURE_SIZE] = Readable::read(r)?;
 874                 match schnorr::Signature::from_slice(&buf) {
 875                         Ok(sig) => Ok(sig),
 876                         Err(_) => return Err(DecodeError::InvalidValue),
 877                 }
 878         }
 879 }
 880
 881 impl Writeable for PaymentPreimage {
 882         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 883                 self.0.write(w)
 884         }
 885 }
 886
 887 impl Readable for PaymentPreimage {
 888         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 889                 let buf: [u8; 32] = Readable::read(r)?;
 890                 Ok(PaymentPreimage(buf))
 891         }
 892 }
 893
 894 impl Writeable for PaymentHash {
 895         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 896                 self.0.write(w)
 897         }
 898 }
 899
 900 impl Readable for PaymentHash {
 901         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 902                 let buf: [u8; 32] = Readable::read(r)?;
 903                 Ok(PaymentHash(buf))
 904         }
 905 }
 906
 907 impl Writeable for PaymentSecret {
 908         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 909                 self.0.write(w)
 910         }
 911 }
 912
 913 impl Readable for PaymentSecret {
 914         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 915                 let buf: [u8; 32] = Readable::read(r)?;
 916                 Ok(PaymentSecret(buf))
 917         }
 918 }
 919
 920 impl<T: Writeable> Writeable for Box<T> {
 921         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 922                 T::write(&**self, w)
 923         }
 924 }
 925
 926 impl<T: Readable> Readable for Box<T> {
 927         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 928                 Ok(Box::new(Readable::read(r)?))
 929         }
 930 }
 931
 932 impl<T: Writeable> Writeable for Option<T> {
 933         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 934                 match *self {
 935                         None => 0u8.write(w)?,
 936                         Some(ref data) => {
 937                                 BigSize(data.serialized_length() as u64 + 1).write(w)?;
 938                                 data.write(w)?;
 939                         }
 940                 }
 941                 Ok(())
 942         }
 943 }
 944
 945 impl<T: Readable> Readable for Option<T>
 946 {
 947         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 948                 let len: BigSize = Readable::read(r)?;
 949                 match len.0 {
 950                         0 => Ok(None),
 951                         len => {
 952                                 let mut reader = FixedLengthReader::new(r, len - 1);
 953                                 Ok(Some(Readable::read(&mut reader)?))
 954                         }
 955                 }
 956         }
 957 }
 958
 959 impl Writeable for Txid {
 960         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 961                 w.write_all(&self[..])
 962         }
 963 }
 964
 965 impl Readable for Txid {
 966         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 967                 use bitcoin::hashes::Hash;
 968
 969                 let buf: [u8; 32] = Readable::read(r)?;
 970                 Ok(Txid::from_slice(&buf[..]).unwrap())
 971         }
 972 }
 973
 974 impl Writeable for BlockHash {
 975         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 976                 w.write_all(&self[..])
 977         }
 978 }
 979
 980 impl Readable for BlockHash {
 981         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 982                 use bitcoin::hashes::Hash;
 983
 984                 let buf: [u8; 32] = Readable::read(r)?;
 985                 Ok(BlockHash::from_slice(&buf[..]).unwrap())
 986         }
 987 }
 988
 989 impl Writeable for ChainHash {
 990         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 991                 w.write_all(self.as_bytes())
 992         }
 993 }
 994
 995 impl Readable for ChainHash {
 996         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 997                 let buf: [u8; 32] = Readable::read(r)?;
 998                 Ok(ChainHash::from(&buf[..]))
 999         }
1000 }
1001
1002 impl Writeable for OutPoint {
1003         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1004                 self.txid.write(w)?;
1005                 self.vout.write(w)?;
1006                 Ok(())
1007         }
1008 }
1009
1010 impl Readable for OutPoint {
1011         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1012                 let txid = Readable::read(r)?;
1013                 let vout = Readable::read(r)?;
1014                 Ok(OutPoint {
1015                         txid,
1016                         vout,
1017                 })
1018         }
1019 }
1020
1021 macro_rules! impl_consensus_ser {
1022         ($bitcoin_type: ty) => {
1023                 impl Writeable for $bitcoin_type {
1024                         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
1025                                 match self.consensus_encode(&mut WriterWriteAdaptor(writer)) {
1026                                         Ok(_) => Ok(()),
1027                                         Err(e) => Err(e),
1028                                 }
1029                         }
1030                 }
1031
1032                 impl Readable for $bitcoin_type {
1033                         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1034                                 match consensus::encode::Decodable::consensus_decode(r) {
1035                                         Ok(t) => Ok(t),
1036                                         Err(consensus::encode::Error::Io(ref e)) if e.kind() == io::ErrorKind::UnexpectedEof => Err(DecodeError::ShortRead),
1037                                         Err(consensus::encode::Error::Io(e)) => Err(DecodeError::Io(e.kind())),
1038                                         Err(_) => Err(DecodeError::InvalidValue),
1039                                 }
1040                         }
1041                 }
1042         }
1043 }
1044 impl_consensus_ser!(Transaction);
1045 impl_consensus_ser!(TxOut);
1046
1047 impl<T: Readable> Readable for Mutex<T> {
1048         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1049                 let t: T = Readable::read(r)?;
1050                 Ok(Mutex::new(t))
1051         }
1052 }
1053 impl<T: Writeable> Writeable for Mutex<T> {
1054         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1055                 self.lock().unwrap().write(w)
1056         }
1057 }
1058
1059 impl<A: Readable, B: Readable> Readable for (A, B) {
1060         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1061                 let a: A = Readable::read(r)?;
1062                 let b: B = Readable::read(r)?;
1063                 Ok((a, b))
1064         }
1065 }
1066 impl<A: Writeable, B: Writeable> Writeable for (A, B) {
1067         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1068                 self.0.write(w)?;
1069                 self.1.write(w)
1070         }
1071 }
1072
1073 impl<A: Readable, B: Readable, C: Readable> Readable for (A, B, C) {
1074         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1075                 let a: A = Readable::read(r)?;
1076                 let b: B = Readable::read(r)?;
1077                 let c: C = Readable::read(r)?;
1078                 Ok((a, b, c))
1079         }
1080 }
1081 impl<A: Writeable, B: Writeable, C: Writeable> Writeable for (A, B, C) {
1082         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1083                 self.0.write(w)?;
1084                 self.1.write(w)?;
1085                 self.2.write(w)
1086         }
1087 }
1088
1089 impl<A: Readable, B: Readable, C: Readable, D: Readable> Readable for (A, B, C, D) {
1090         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1091                 let a: A = Readable::read(r)?;
1092                 let b: B = Readable::read(r)?;
1093                 let c: C = Readable::read(r)?;
1094                 let d: D = Readable::read(r)?;
1095                 Ok((a, b, c, d))
1096         }
1097 }
1098 impl<A: Writeable, B: Writeable, C: Writeable, D: Writeable> Writeable for (A, B, C, D) {
1099         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1100                 self.0.write(w)?;
1101                 self.1.write(w)?;
1102                 self.2.write(w)?;
1103                 self.3.write(w)
1104         }
1105 }
1106
1107 impl Writeable for () {
1108         fn write<W: Writer>(&self, _: &mut W) -> Result<(), io::Error> {
1109                 Ok(())
1110         }
1111 }
1112 impl Readable for () {
1113         fn read<R: Read>(_r: &mut R) -> Result<Self, DecodeError> {
1114                 Ok(())
1115         }
1116 }
1117
1118 impl Writeable for String {
1119         #[inline]
1120         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1121                 CollectionLength(self.len() as u64).write(w)?;
1122                 w.write_all(self.as_bytes())
1123         }
1124 }
1125 impl Readable for String {
1126         #[inline]
1127         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1128                 let v: Vec<u8> = Readable::read(r)?;
1129                 let ret = String::from_utf8(v).map_err(|_| DecodeError::InvalidValue)?;
1130                 Ok(ret)
1131         }
1132 }
1133
1134 /// Represents a hostname for serialization purposes.
1135 /// Only the character set and length will be validated.
1136 /// The character set consists of ASCII alphanumeric characters, hyphens, and periods.
1137 /// Its length is guaranteed to be representable by a single byte.
1138 /// This serialization is used by [`BOLT 7`] hostnames.
1139 ///
1140 /// [`BOLT 7`]: https://github.com/lightning/bolts/blob/master/07-routing-gossip.md
1141 #[derive(Clone, Debug, PartialEq, Eq)]
1142 pub struct Hostname(String);
1143 impl Hostname {
1144         /// Returns the length of the hostname.
1145         pub fn len(&self) -> u8 {
1146                 (&self.0).len() as u8
1147         }
1148 }
1149 impl Deref for Hostname {
1150         type Target = String;
1151
1152         fn deref(&self) -> &Self::Target {
1153                 &self.0
1154         }
1155 }
1156 impl From<Hostname> for String {
1157         fn from(hostname: Hostname) -> Self {
1158                 hostname.0
1159         }
1160 }
1161 impl TryFrom<Vec<u8>> for Hostname {
1162         type Error = ();
1163
1164         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
1165                 if let Ok(s) = String::from_utf8(bytes) {
1166                         Hostname::try_from(s)
1167                 } else {
1168                         Err(())
1169                 }
1170         }
1171 }
1172 impl TryFrom<String> for Hostname {
1173         type Error = ();
1174
1175         fn try_from(s: String) -> Result<Self, Self::Error> {
1176                 if s.len() <= 255 && s.chars().all(|c|
1177                         c.is_ascii_alphanumeric() ||
1178                         c == '.' ||
1179                         c == '-'
1180                 ) {
1181                         Ok(Hostname(s))
1182                 } else {
1183                         Err(())
1184                 }
1185         }
1186 }
1187 impl Writeable for Hostname {
1188         #[inline]
1189         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1190                 self.len().write(w)?;
1191                 w.write_all(self.as_bytes())
1192         }
1193 }
1194 impl Readable for Hostname {
1195         #[inline]
1196         fn read<R: Read>(r: &mut R) -> Result<Hostname, DecodeError> {
1197                 let len: u8 = Readable::read(r)?;
1198                 let mut vec = Vec::with_capacity(len.into());
1199                 vec.resize(len.into(), 0);
1200                 r.read_exact(&mut vec)?;
1201                 Hostname::try_from(vec).map_err(|_| DecodeError::InvalidValue)
1202         }
1203 }
1204
1205 impl Writeable for Duration {
1206         #[inline]
1207         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1208                 self.as_secs().write(w)?;
1209                 self.subsec_nanos().write(w)
1210         }
1211 }
1212 impl Readable for Duration {
1213         #[inline]
1214         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
1215                 let secs = Readable::read(r)?;
1216                 let nanos = Readable::read(r)?;
1217                 Ok(Duration::new(secs, nanos))
1218         }
1219 }
1220
1221 #[cfg(test)]
1222 mod tests {
1223         use core::convert::TryFrom;
1224         use crate::util::ser::{Readable, Hostname, Writeable};
1225
1226         #[test]
1227         fn hostname_conversion() {
1228                 assert_eq!(Hostname::try_from(String::from("a-test.com")).unwrap().as_str(), "a-test.com");
1229
1230                 assert!(Hostname::try_from(String::from("\"")).is_err());
1231                 assert!(Hostname::try_from(String::from("$")).is_err());
1232                 assert!(Hostname::try_from(String::from("⚡")).is_err());
1233                 let mut large_vec = Vec::with_capacity(256);
1234                 large_vec.resize(256, b'A');
1235                 assert!(Hostname::try_from(String::from_utf8(large_vec).unwrap()).is_err());
1236         }
1237
1238         #[test]
1239         fn hostname_serialization() {
1240                 let hostname = Hostname::try_from(String::from("test")).unwrap();
1241                 let mut buf: Vec<u8> = Vec::new();
1242                 hostname.write(&mut buf).unwrap();
1243                 assert_eq!(Hostname::read(&mut buf.as_slice()).unwrap().as_str(), "test");
1244         }
1245 }