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fix: add backward compat for DlcOffer without protocol_version #238

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Merged
matthewjablack merged 1 commit into from
Jun 27, 2026
+17 −2
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fix: add backward compat for DlcOffer without protocol_version #238

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19 changes: 17 additions & 2 deletions packages/messaging/lib/messages/DlcOffer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -127,8 +127,23 @@ export class DlcOffer implements IDlcMessage {
);
}

// Read protocol_version as 4 bytes (u32) as per dlcspecs PR #163
instance.protocolVersion = reader.readUInt32BE();
// BACKWARD COMPATIBILITY: Detect old vs new format
// New format: [type][protocol_version: 4 bytes][contract_flags: 1 byte][chain_hash: 32 bytes]
// Old format: [type][contract_flags: 1 byte][chain_hash: 32 bytes]
//
// Heuristic: peek first 4 bytes as u32. In new format this is protocol_version (1-10).
// In old format these are contract_flags (0x00/0x01) + first 3 chain_hash bytes,
// which always produces values outside 1-10 for any Bitcoin network.
const peekBuf = Buffer.from(
reader.buffer.subarray(reader.position, reader.position + 4),
);
const possibleProtocolVersion = new BufferReader(peekBuf).readUInt32BE();

if (possibleProtocolVersion >= 1 && possibleProtocolVersion <= 10) {
instance.protocolVersion = reader.readUInt32BE();
} else {
instance.protocolVersion = 1;
}
instance.contractFlags = reader.readBytes(1);

instance.chainHash = reader.readBytes(32);
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