Add macros for building TLV (de)serializers.

There's quite a bit of machinery included here, but it neatly
avoids any dynamic allocation during TLV deserialization, and the
calling side looks nice and simple. The macro-generated code is
pretty nice, though has some redundant if statements (I haven't
checked if they get optimized out yet, but I can't imagine they
don't).

Author: TheBlueMatt

lightning/src/util/ser_macros.rs

@@ -1,3 +1,109 @@
+macro_rules! encode_tlv {
+	($stream: expr, {$(($type: expr, $field: expr)),*}) => { {
+		use util::ser::{BigSize, LengthCalculatingWriter};
+		$(
+			BigSize($type).write($stream)?;
+			let mut len_calc = LengthCalculatingWriter(0);
+			$field.write(&mut len_calc)?;
+			BigSize(len_calc.0 as u64).write($stream)?;
+			$field.write($stream)?;
+		)*
+	} }
+}
+
+macro_rules! encode_varint_length_prefixed_tlv {
+	($stream: expr, {$(($type: expr, $field: expr)),*}) => { {
+		use util::ser::{BigSize, LengthCalculatingWriter};
+		let mut len = LengthCalculatingWriter(0);
+		{
+			$(
+				BigSize($type).write(&mut len)?;
+				let mut field_len = LengthCalculatingWriter(0);
+				$field.write(&mut field_len)?;
+				BigSize(field_len.0 as u64).write(&mut len)?;
+				len.0 += field_len.0;
+			)*
+		}
+
+		BigSize(len.0 as u64).write($stream)?;
+		encode_tlv!($stream, {
+			$(($type, $field)),*
+		});
+	} }
+}
+
+macro_rules! decode_tlv {
+	($stream: expr, {$(($reqtype: expr, $reqfield: ident)),*}, {$(($type: expr, $field: ident)),*}) => { {
+		use ln::msgs::DecodeError;
+		let mut last_seen_type: Option<u64> = None;
+		'tlv_read: loop {
+			use util::ser;
+
+			// First decode the type of this TLV:
+			let typ: ser::BigSize = {
+				// We track whether any bytes were read during the consensus_decode call to
+				// determine whether we should break or return ShortRead if we get an
+				// UnexpectedEof. This should in every case be largely cosmetic, but its nice to
+				// pass the TLV test vectors exactly, which requre this distinction.
+				let mut tracking_reader = ser::ReadTrackingReader::new($stream);
+				match ser::Readable::read(&mut tracking_reader) {
+					Err(DecodeError::ShortRead) => {
+						if !tracking_reader.have_read {
+							break 'tlv_read
+						} else {
+							Err(DecodeError::ShortRead)?
+						}
+					},
+					Err(e) => Err(e)?,
+					Ok(t) => t,
+				}
+			};
+
+			// Types must be unique and monotonically increasing:
+			match last_seen_type {
+				Some(t) if typ.0 <= t => {
+					Err(DecodeError::InvalidValue)?
+				},
+				_ => {},
+			}
+			// As we read types, make sure we hit every required type:
+			$(if (last_seen_type.is_none() || last_seen_type.unwrap() < $reqtype) && typ.0 > $reqtype {
+				Err(DecodeError::InvalidValue)?
+			})*
+			last_seen_type = Some(typ.0);
+
+			// Finally, read the length and value itself:
+			let length: ser::BigSize = Readable::read($stream)?;
+			let mut s = ser::FixedLengthReader::new($stream, length.0);
+			match typ.0 {
+				$($reqtype => {
+					$reqfield = ser::Readable::read(&mut s)?;
+					if s.bytes_remain() {
+						s.eat_remaining()?; // Return ShortRead if there's actually not enough bytes
+						Err(DecodeError::InvalidValue)?
+					}
+				},)*
+				$($type => {
+					$field = Some(ser::Readable::read(&mut s)?);
+					if s.bytes_remain() {
+						s.eat_remaining()?; // Return ShortRead if there's actually not enough bytes
+						Err(DecodeError::InvalidValue)?
+					}
+				},)*
+				x if x % 2 == 0 => {
+					Err(DecodeError::UnknownRequiredFeature)?
+				},
+				_ => {},
+			}
+			s.eat_remaining()?;
+		}
+		// Make sure we got to each required type after we've read every TLV:
+		$(if last_seen_type.is_none() || last_seen_type.unwrap() < $reqtype {
+			Err(DecodeError::InvalidValue)?
+		})*
+	} }
+}
+
 macro_rules! impl_writeable {
 	($st:ident, $len: expr, {$($field:ident),*}) => {
 		impl ::util::ser::Writeable for $st {
@@ -40,3 +146,224 @@ macro_rules! impl_writeable_len_match {
 		}
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use std::io::{Cursor, Read};
+	use ln::msgs::DecodeError;
+	use util::ser::{Readable, Writeable, HighZeroBytesDroppedVarInt, VecWriter};
+	use secp256k1::PublicKey;
+
+	// The BOLT TLV test cases don't include any tests which use our "required-value" logic since
+	// the encoding layer in the BOLTs has no such concept, though it makes our macros easier to
+	// work with so they're baked into the decoder. Thus, we have a few additional tests below
+	fn tlv_reader(s: &[u8]) -> Result<(u64, u32, Option<u32>), DecodeError> {
+		let mut s = Cursor::new(s);
+		let mut a: u64 = 0;
+		let mut b: u32 = 0;
+		let mut c: Option<u32> = None;
+		decode_tlv!(&mut s, {(2, a), (3, b)}, {(4, c)});
+		Ok((a, b, c))
+	}
+
+	#[test]
+	fn tlv_v_short_read() {
+		// We only expect a u32 for type 3 (which we are given), but the L says its 8 bytes.
+		if let Err(DecodeError::ShortRead) = tlv_reader(&::hex::decode(
+				concat!("0100", "0208deadbeef1badbeef", "0308deadbeef")
+				).unwrap()[..]) {
+		} else { panic!(); }
+	}
+
+	#[test]
+	fn tlv_types_out_of_order() {
+		if let Err(DecodeError::InvalidValue) = tlv_reader(&::hex::decode(
+				concat!("0100", "0304deadbeef", "0208deadbeef1badbeef")
+				).unwrap()[..]) {
+		} else { panic!(); }
+		// ...even if its some field we don't understand
+		if let Err(DecodeError::InvalidValue) = tlv_reader(&::hex::decode(
+				concat!("0208deadbeef1badbeef", "0100", "0304deadbeef")
+				).unwrap()[..]) {
+		} else { panic!(); }
+	}
+
+	#[test]
+	fn tlv_req_type_missing_or_extra() {
+		// It's also bad if they included even fields we don't understand
+		if let Err(DecodeError::UnknownRequiredFeature) = tlv_reader(&::hex::decode(
+				concat!("0100", "0208deadbeef1badbeef", "0304deadbeef", "0600")
+				).unwrap()[..]) {
+		} else { panic!(); }
+		// ... or if they're missing fields we need
+		if let Err(DecodeError::InvalidValue) = tlv_reader(&::hex::decode(
+				concat!("0100", "0208deadbeef1badbeef")
+				).unwrap()[..]) {
+		} else { panic!(); }
+		// ... even if that field is even
+		if let Err(DecodeError::InvalidValue) = tlv_reader(&::hex::decode(
+				concat!("0304deadbeef", "0500")
+				).unwrap()[..]) {
+		} else { panic!(); }
+	}
+
+	#[test]
+	fn tlv_simple_good_cases() {
+		assert_eq!(tlv_reader(&::hex::decode(
+				concat!("0208deadbeef1badbeef", "03041bad1dea")
+				).unwrap()[..]).unwrap(),
+			(0xdeadbeef1badbeef, 0x1bad1dea, None));
+		assert_eq!(tlv_reader(&::hex::decode(
+				concat!("0208deadbeef1badbeef", "03041bad1dea", "040401020304")
+				).unwrap()[..]).unwrap(),
+			(0xdeadbeef1badbeef, 0x1bad1dea, Some(0x01020304)));
+	}
+
+	impl<R: Read> Readable<R> for (PublicKey, u64, u64) {
+		#[inline]
+		fn read(reader: &mut R) -> Result<(PublicKey, u64, u64), DecodeError> {
+			Ok((Readable::read(reader)?, Readable::read(reader)?, Readable::read(reader)?))
+		}
+	}
+
+	// BOLT TLV test cases
+	fn tlv_reader_n1(s: &[u8]) -> Result<(Option<HighZeroBytesDroppedVarInt<u64>>, Option<u64>, Option<(PublicKey, u64, u64)>, Option<u16>), DecodeError> {
+		let mut s = Cursor::new(s);
+		let mut tlv1: Option<HighZeroBytesDroppedVarInt<u64>> = None;
+		let mut tlv2: Option<u64> = None;
+		let mut tlv3: Option<(PublicKey, u64, u64)> = None;
+		let mut tlv4: Option<u16> = None;
+		decode_tlv!(&mut s, {}, {(1, tlv1), (2, tlv2), (3, tlv3), (254, tlv4)});
+		Ok((tlv1, tlv2, tlv3, tlv4))
+	}
+
+	#[test]
+	fn bolt_tlv_bogus_stream() {
+		macro_rules! do_test {
+			($stream: expr, $reason: ident) => {
+				if let Err(DecodeError::$reason) = tlv_reader_n1(&::hex::decode($stream).unwrap()[..]) {
+				} else { panic!(); }
+			}
+		}
+
+		// TLVs from the BOLT test cases which should not decode as either n1 or n2
+		do_test!(concat!("fd01"), ShortRead);
+		do_test!(concat!("fd0001", "00"), InvalidValue);
+		do_test!(concat!("fd0101"), ShortRead);
+		do_test!(concat!("0f", "fd"), ShortRead);
+		do_test!(concat!("0f", "fd26"), ShortRead);
+		do_test!(concat!("0f", "fd2602"), ShortRead);
+		do_test!(concat!("0f", "fd0001", "00"), InvalidValue);
+		do_test!(concat!("0f", "fd0201", "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"), ShortRead);
+
+		do_test!(concat!("12", "00"), UnknownRequiredFeature);
+		do_test!(concat!("fd0102", "00"), UnknownRequiredFeature);
+		do_test!(concat!("fe01000002", "00"), UnknownRequiredFeature);
+		do_test!(concat!("ff0100000000000002", "00"), UnknownRequiredFeature);
+	}
+
+	#[test]
+	fn bolt_tlv_bogus_n1_stream() {
+		macro_rules! do_test {
+			($stream: expr, $reason: ident) => {
+				if let Err(DecodeError::$reason) = tlv_reader_n1(&::hex::decode($stream).unwrap()[..]) {
+				} else { panic!(); }
+			}
+		}
+
+		// TLVs from the BOLT test cases which should not decode as n1
+		do_test!(concat!("01", "09", "ffffffffffffffffff"), InvalidValue);
+		do_test!(concat!("01", "01", "00"), InvalidValue);
+		do_test!(concat!("01", "02", "0001"), InvalidValue);
+		do_test!(concat!("01", "03", "000100"), InvalidValue);
+		do_test!(concat!("01", "04", "00010000"), InvalidValue);
+		do_test!(concat!("01", "05", "0001000000"), InvalidValue);
+		do_test!(concat!("01", "06", "000100000000"), InvalidValue);
+		do_test!(concat!("01", "07", "00010000000000"), InvalidValue);
+		do_test!(concat!("01", "08", "0001000000000000"), InvalidValue);
+		do_test!(concat!("02", "07", "01010101010101"), ShortRead);
+		do_test!(concat!("02", "09", "010101010101010101"), InvalidValue);
+		do_test!(concat!("03", "21", "023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb"), ShortRead);
+		do_test!(concat!("03", "29", "023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb0000000000000001"), ShortRead);
+		do_test!(concat!("03", "30", "023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb000000000000000100000000000001"), ShortRead);
+		do_test!(concat!("03", "31", "043da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb00000000000000010000000000000002"), InvalidValue);
+		do_test!(concat!("03", "32", "023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb0000000000000001000000000000000001"), InvalidValue);
+		do_test!(concat!("fd00fe", "00"), ShortRead);
+		do_test!(concat!("fd00fe", "01", "01"), ShortRead);
+		do_test!(concat!("fd00fe", "03", "010101"), InvalidValue);
+		do_test!(concat!("00", "00"), UnknownRequiredFeature);
+
+		do_test!(concat!("02", "08", "0000000000000226", "01", "01", "2a"), InvalidValue);
+		do_test!(concat!("02", "08", "0000000000000231", "02", "08", "0000000000000451"), InvalidValue);
+		do_test!(concat!("1f", "00", "0f", "01", "2a"), InvalidValue);
+		do_test!(concat!("1f", "00", "1f", "01", "2a"), InvalidValue);
+
+		// The last BOLT test modified to not require creating a new decoder for one trivial test.
+		do_test!(concat!("ffffffffffffffffff", "00", "01", "00"), InvalidValue);
+	}
+
+	#[test]
+	fn bolt_tlv_valid_n1_stream() {
+		macro_rules! do_test {
+			($stream: expr, $tlv1: expr, $tlv2: expr, $tlv3: expr, $tlv4: expr) => {
+				if let Ok((tlv1, tlv2, tlv3, tlv4)) = tlv_reader_n1(&::hex::decode($stream).unwrap()[..]) {
+					assert_eq!(tlv1.map(|v| v.0), $tlv1);
+					assert_eq!(tlv2, $tlv2);
+					assert_eq!(tlv3, $tlv3);
+					assert_eq!(tlv4, $tlv4);
+				} else { panic!(); }
+			}
+		}
+
+		do_test!(concat!(""), None, None, None, None);
+		do_test!(concat!("21", "00"), None, None, None, None);
+		do_test!(concat!("fd0201", "00"), None, None, None, None);
+		do_test!(concat!("fd00fd", "00"), None, None, None, None);
+		do_test!(concat!("fd00ff", "00"), None, None, None, None);
+		do_test!(concat!("fe02000001", "00"), None, None, None, None);
+		do_test!(concat!("ff0200000000000001", "00"), None, None, None, None);
+
+		do_test!(concat!("01", "00"), Some(0), None, None, None);
+		do_test!(concat!("01", "01", "01"), Some(1), None, None, None);
+		do_test!(concat!("01", "02", "0100"), Some(256), None, None, None);
+		do_test!(concat!("01", "03", "010000"), Some(65536), None, None, None);
+		do_test!(concat!("01", "04", "01000000"), Some(16777216), None, None, None);
+		do_test!(concat!("01", "05", "0100000000"), Some(4294967296), None, None, None);
+		do_test!(concat!("01", "06", "010000000000"), Some(1099511627776), None, None, None);
+		do_test!(concat!("01", "07", "01000000000000"), Some(281474976710656), None, None, None);
+		do_test!(concat!("01", "08", "0100000000000000"), Some(72057594037927936), None, None, None);
+		do_test!(concat!("02", "08", "0000000000000226"), None, Some((0 << 30) | (0 << 5) | (550 << 0)), None, None);
+		do_test!(concat!("03", "31", "023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb00000000000000010000000000000002"),
+			None, None, Some((
+				PublicKey::from_slice(&::hex::decode("023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb").unwrap()[..]).unwrap(), 1, 2)),
+			None);
+		do_test!(concat!("fd00fe", "02", "0226"), None, None, None, Some(550));
+	}
+
+	fn do_simple_test_tlv_write() -> Result<(), ::std::io::Error> {
+		let mut stream = VecWriter(Vec::new());
+
+		stream.0.clear();
+		encode_varint_length_prefixed_tlv!(&mut stream, { (1, 1u8) });
+		assert_eq!(stream.0, ::hex::decode("03010101").unwrap());
+
+		stream.0.clear();
+		encode_varint_length_prefixed_tlv!(&mut stream, { (4, 0xabcdu16) });
+		assert_eq!(stream.0, ::hex::decode("040402abcd").unwrap());
+
+		stream.0.clear();
+		encode_varint_length_prefixed_tlv!(&mut stream, { (0xff, 0xabcdu16) });
+		assert_eq!(stream.0, ::hex::decode("06fd00ff02abcd").unwrap());
+
+		stream.0.clear();
+		encode_varint_length_prefixed_tlv!(&mut stream, { (0, 1u64), (0xff, HighZeroBytesDroppedVarInt(0u64)) });
+		assert_eq!(stream.0, ::hex::decode("0e00080000000000000001fd00ff00").unwrap());
+
+		Ok(())
+	}
+
+	#[test]
+	fn simple_test_tlv_write() {
+		do_simple_test_tlv_write().unwrap();
+	}
+}