bolt: implement tx_signatures message codec #28
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| //! BOLT 2 `tx_signatures` message. | ||
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| use super::BoltError; | ||
| use super::tlv::TlvStream; | ||
| use super::types::{ChannelId, Txid}; | ||
| use super::wire::WireFormat; | ||
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| /// A witness stack for a single transaction input. | ||
| /// | ||
| /// Each inner `Vec<u8>` is a single witness stack item. | ||
| #[derive(Debug, Clone, PartialEq, Eq)] | ||
| pub struct Witness(pub Vec<Vec<u8>>); | ||
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| /// BOLT 2 `tx_signatures` message (type 71). | ||
| /// | ||
| /// Sent during interactive transaction construction to provide the sender's | ||
| /// witnesses for the negotiated transaction. Both peers exchange | ||
| /// `tx_signatures` before broadcasting. | ||
| #[derive(Debug, Clone, PartialEq, Eq)] | ||
| pub struct TxSignatures { | ||
| /// The channel ID. | ||
| pub channel_id: ChannelId, | ||
| /// The transaction ID (little-endian, Bitcoin serialization). | ||
| pub txid: Txid, | ||
| /// Witnesses for the transaction inputs. | ||
| pub witnesses: Vec<Witness>, | ||
| /// Optional TLV extensions. | ||
| pub tlvs: TxSignaturesTlvs, | ||
| } | ||
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Owner
There was a problem hiding this comment. We also should implement the |
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| /// TLV extensions for the `tx_signatures` message. | ||
| #[derive(Debug, Clone, Default, PartialEq, Eq)] | ||
| pub struct TxSignaturesTlvs {} | ||
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Owner
There was a problem hiding this comment. Please actually implement the TLVs rather than ignoring them. |
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| impl TxSignatures { | ||
| /// Encodes to wire format (without message type prefix). | ||
| /// | ||
| /// # Panics | ||
| /// | ||
| /// Panics if the number of witnesses or the number of items in any witness | ||
| /// stack exceeds `u16::MAX`. | ||
| #[must_use] | ||
| pub fn encode(&self) -> Vec<u8> { | ||
| let mut out = Vec::new(); | ||
| self.channel_id.write(&mut out); | ||
| self.txid.write(&mut out); | ||
| assert!( | ||
| self.witnesses.len() <= usize::from(u16::MAX), | ||
| "witness count exceeds u16::MAX" | ||
| ); | ||
| #[allow(clippy::cast_possible_truncation)] | ||
| (self.witnesses.len() as u16).write(&mut out); | ||
| for witness in &self.witnesses { | ||
| assert!( | ||
| witness.0.len() <= usize::from(u16::MAX), | ||
| "witness stack item count exceeds u16::MAX" | ||
| ); | ||
| #[allow(clippy::cast_possible_truncation)] | ||
| (witness.0.len() as u16).write(&mut out); | ||
| for item in &witness.0 { | ||
| item.write(&mut out); | ||
| } | ||
| } | ||
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| // Encode TLVs | ||
| let tlv_stream = TlvStream::new(); | ||
| out.extend(tlv_stream.encode()); | ||
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| out | ||
| } | ||
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| /// Decodes from wire format (without message type prefix). | ||
| /// | ||
| /// # Errors | ||
| /// | ||
| /// Returns `Truncated` if the payload is too short for any fixed field or | ||
| /// declared variable-length data. | ||
| pub fn decode(payload: &[u8]) -> Result<Self, BoltError> { | ||
| let mut cursor = payload; | ||
| let channel_id: ChannelId = WireFormat::read(&mut cursor)?; | ||
| let txid: Txid = WireFormat::read(&mut cursor)?; | ||
| let num_witnesses: u16 = WireFormat::read(&mut cursor)?; | ||
| let mut witnesses = Vec::with_capacity(num_witnesses as usize); | ||
|
There was a problem hiding this comment. Looks like recipe for an Out-Of-Memory (OOM) crash in case the fuzzer decides on a high value for I'd say it's better to let the vector grow dynamically:
Owner
There was a problem hiding this comment. The fuzzer shouldn't be choosing values that get decoded, only values that get encoded. Either way, |
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| for _ in 0..num_witnesses { | ||
| let num_items: u16 = WireFormat::read(&mut cursor)?; | ||
| let mut stack = Vec::with_capacity(num_items as usize); | ||
| for _ in 0..num_items { | ||
| let item: Vec<u8> = WireFormat::read(&mut cursor)?; | ||
| stack.push(item); | ||
| } | ||
| witnesses.push(Witness(stack)); | ||
| } | ||
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| // Decode TLVs (remaining bytes); no known even types for this message. | ||
| let _tlv_stream = TlvStream::decode(cursor)?; | ||
| let tlvs = TxSignaturesTlvs {}; | ||
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| Ok(Self { | ||
| channel_id, | ||
| txid, | ||
| witnesses, | ||
| tlvs, | ||
| }) | ||
| } | ||
| } | ||
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| #[cfg(test)] | ||
| mod tests { | ||
| use super::super::{CHANNEL_ID_SIZE, TXID_SIZE}; | ||
| use super::*; | ||
| use secp256k1::hashes::Hash; | ||
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| fn sample_txid() -> Txid { | ||
| Txid::from_byte_array([0xcc; TXID_SIZE]) | ||
| } | ||
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| #[test] | ||
| fn roundtrip() { | ||
| let original = TxSignatures { | ||
| channel_id: ChannelId::new([0xab; CHANNEL_ID_SIZE]), | ||
| txid: sample_txid(), | ||
| witnesses: vec![ | ||
| Witness(vec![vec![0x01, 0x02], vec![0x03]]), | ||
| Witness(vec![vec![0xde, 0xad, 0xbe, 0xef]]), | ||
| ], | ||
| tlvs: TxSignaturesTlvs::default(), | ||
| }; | ||
| let encoded = original.encode(); | ||
| let decoded = TxSignatures::decode(&encoded).unwrap(); | ||
| assert_eq!(original, decoded); | ||
| } | ||
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| #[test] | ||
| fn roundtrip_empty_witnesses() { | ||
| let original = TxSignatures { | ||
| channel_id: ChannelId::new([0x00; CHANNEL_ID_SIZE]), | ||
| txid: sample_txid(), | ||
| witnesses: vec![], | ||
| tlvs: TxSignaturesTlvs::default(), | ||
| }; | ||
| let encoded = original.encode(); | ||
| // channel_id(32) + txid(32) + num_witnesses(2) = 66 | ||
| assert_eq!(encoded.len(), 66); | ||
| let decoded = TxSignatures::decode(&encoded).unwrap(); | ||
| assert_eq!(original, decoded); | ||
| } | ||
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| #[test] | ||
| fn roundtrip_empty_stack_items() { | ||
| // A witness with zero stack items is valid wire-wise. | ||
| let original = TxSignatures { | ||
| channel_id: ChannelId::new([0x11; CHANNEL_ID_SIZE]), | ||
| txid: sample_txid(), | ||
| witnesses: vec![Witness(vec![]), Witness(vec![])], | ||
| tlvs: TxSignaturesTlvs::default(), | ||
| }; | ||
| let encoded = original.encode(); | ||
| let decoded = TxSignatures::decode(&encoded).unwrap(); | ||
| assert_eq!(original, decoded); | ||
| } | ||
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| #[test] | ||
| fn decode_ignores_unknown_odd_tlv() { | ||
| let original = TxSignatures { | ||
| channel_id: ChannelId::new([0xff; CHANNEL_ID_SIZE]), | ||
| txid: sample_txid(), | ||
| witnesses: vec![], | ||
| tlvs: TxSignaturesTlvs::default(), | ||
| }; | ||
| let mut encoded = original.encode(); | ||
| // Append unknown odd TLV: type=3, length=2, value=[0xaa, 0xbb] | ||
| encoded.extend_from_slice(&[0x03, 0x02, 0xaa, 0xbb]); | ||
| let decoded = TxSignatures::decode(&encoded).unwrap(); | ||
| assert_eq!(decoded, original); | ||
| } | ||
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| #[test] | ||
| fn encode_size() { | ||
| // channel_id(32) + txid(32) + num_witnesses(2) + num_items(2) + item_len(2) + item(3) = 73 | ||
| let msg = TxSignatures { | ||
| channel_id: ChannelId::new([0x42; CHANNEL_ID_SIZE]), | ||
| txid: sample_txid(), | ||
| witnesses: vec![Witness(vec![vec![0xaa, 0xbb, 0xcc]])], | ||
| tlvs: TxSignaturesTlvs::default(), | ||
| }; | ||
| let encoded = msg.encode(); | ||
| assert_eq!(encoded.len(), 32 + 32 + 2 + 2 + 2 + 3); | ||
| } | ||
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| #[test] | ||
| fn decode_empty() { | ||
| assert_eq!( | ||
| TxSignatures::decode(&[]), | ||
| Err(BoltError::Truncated { | ||
| expected: CHANNEL_ID_SIZE, | ||
| actual: 0 | ||
| }) | ||
| ); | ||
| } | ||
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| #[test] | ||
| fn decode_truncated_channel_id() { | ||
| assert_eq!( | ||
| TxSignatures::decode(&[0x00; 20]), | ||
| Err(BoltError::Truncated { | ||
| expected: CHANNEL_ID_SIZE, | ||
| actual: 20 | ||
| }) | ||
| ); | ||
| } | ||
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| #[test] | ||
| fn decode_truncated_txid() { | ||
| let mut data = vec![0xaa; CHANNEL_ID_SIZE]; | ||
| data.extend_from_slice(&[0x00; 20]); // only 20 bytes of txid | ||
| assert_eq!( | ||
| TxSignatures::decode(&data), | ||
| Err(BoltError::Truncated { | ||
| expected: TXID_SIZE, | ||
| actual: 20 | ||
| }) | ||
| ); | ||
| } | ||
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| #[test] | ||
| fn decode_truncated_witnesses_count() { | ||
| let mut data = vec![0xaa; CHANNEL_ID_SIZE]; | ||
| data.extend_from_slice(&[0xcc; TXID_SIZE]); | ||
| data.push(0x00); // only 1 byte of witnesses count | ||
| assert_eq!( | ||
| TxSignatures::decode(&data), | ||
| Err(BoltError::Truncated { | ||
| expected: 2, | ||
| actual: 1 | ||
| }) | ||
| ); | ||
| } | ||
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| #[test] | ||
| fn decode_truncated_stack_items_count() { | ||
| let mut data = vec![0xaa; CHANNEL_ID_SIZE]; | ||
| data.extend_from_slice(&[0xcc; TXID_SIZE]); | ||
| data.extend_from_slice(&[0x00, 0x01]); // num_witnesses = 1 | ||
| data.push(0x00); // only 1 byte of stack items count | ||
| assert_eq!( | ||
| TxSignatures::decode(&data), | ||
| Err(BoltError::Truncated { | ||
| expected: 2, | ||
| actual: 1 | ||
| }) | ||
| ); | ||
| } | ||
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| #[test] | ||
| fn decode_truncated_item_data() { | ||
| let mut data = vec![0xaa; CHANNEL_ID_SIZE]; | ||
| data.extend_from_slice(&[0xcc; TXID_SIZE]); | ||
| data.extend_from_slice(&[0x00, 0x01]); // num_witnesses = 1 | ||
| data.extend_from_slice(&[0x00, 0x01]); // num_stack_items = 1 | ||
| data.extend_from_slice(&[0x00, 0x05]); // item_len = 5 | ||
| data.extend_from_slice(&[0x11, 0x22]); // only 2 bytes of item data | ||
| assert_eq!( | ||
| TxSignatures::decode(&data), | ||
| Err(BoltError::Truncated { | ||
| expected: 5, | ||
| actual: 2 | ||
| }) | ||
| ); | ||
| } | ||
| } | ||
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IIUC, a witness should just be
Vec<u8>, notVec<Vec<u8>>.