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Added code to parse variable length block headers, necessary for DOGE.

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This commit is contained in:
CalDescent 2021-07-29 09:00:55 +01:00
parent ed997af043
commit 130f3f6d41
1 changed files with 35 additions and 6 deletions
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41
src/main/java/org/qortal/crosschain/ElectrumX.java
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@ -33,6 +33,7 @@ import org.qortal.crypto.TrustlessSSLSocketFactory;
import com.google.common.hash.HashCode; import com.google.common.hash.HashCode;
import com.google.common.primitives.Bytes; import com.google.common.primitives.Bytes;
import org.qortal.utils.BitTwiddling;
/** ElectrumX network support for querying Bitcoiny-related info like block headers, transaction outputs, etc. */ /** ElectrumX network support for querying Bitcoiny-related info like block headers, transaction outputs, etc. */
public class ElectrumX extends BitcoinyBlockchainProvider { public class ElectrumX extends BitcoinyBlockchainProvider {
@ -171,13 +172,41 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
Long returnedCount = (Long) countObj; Long returnedCount = (Long) countObj;
String hex = (String) hexObj; String hex = (String) hexObj;
byte[] raw = HashCode.fromString(hex).asBytes();
if (raw.length != returnedCount * BLOCK_HEADER_LENGTH)
throw new ForeignBlockchainException.NetworkException("Unexpected raw header length in JSON from ElectrumX blockchain.block.headers RPC");
List<byte[]> rawBlockHeaders = new ArrayList<>(returnedCount.intValue()); List<byte[]> rawBlockHeaders = new ArrayList<>(returnedCount.intValue());
for (int i = 0; i < returnedCount; ++i)
rawBlockHeaders.add(Arrays.copyOfRange(raw, i * BLOCK_HEADER_LENGTH, (i + 1) * BLOCK_HEADER_LENGTH)); byte[] raw = HashCode.fromString(hex).asBytes();
// Most chains use a fixed length 80 byte header, so block headers can be split up by dividing the hex into
// 80-byte segments. However, some chains such as DOGE use variable length headers due to AuxPoW or other
// reasons. In these cases we can identify the start of each block header by the location of the block version
// numbers. Each block starts with a version number, and for DOGE this is easily identifiable (6422788) at the
// time of writing (Jul 2021). If we encounter a chain that is using more generic version numbers (e.g. 1)
// and can't be used to accurately identify block indexes, then there are sufficient checks to ensure an
// exception is thrown.
if (raw.length == returnedCount * BLOCK_HEADER_LENGTH) {
// Fixed-length header (BTC, LTC, etc)
for (int i = 0; i < returnedCount; ++i) {
rawBlockHeaders.add(Arrays.copyOfRange(raw, i * BLOCK_HEADER_LENGTH, (i + 1) * BLOCK_HEADER_LENGTH));
}
}
else if (raw.length > returnedCount * BLOCK_HEADER_LENGTH) {
// Assume AuxPoW variable length header (DOGE)
int referenceVersion = BitTwiddling.intFromLEBytes(raw, 0); // DOGE uses 6422788 at time of commit (Jul 2021)
for (int i = 0; i < raw.length - 4; ++i) {
// Locate the start of each block by its version number
if (BitTwiddling.intFromLEBytes(raw, i) == referenceVersion) {
rawBlockHeaders.add(Arrays.copyOfRange(raw, i, i + BLOCK_HEADER_LENGTH));
}
}
// Ensure that we found the correct number of block headers
if (rawBlockHeaders.size() != count) {
throw new ForeignBlockchainException.NetworkException("Unexpected raw header contents in JSON from ElectrumX blockchain.block.headers RPC.");
}
}
else if (raw.length != returnedCount * BLOCK_HEADER_LENGTH) {
throw new ForeignBlockchainException.NetworkException("Unexpected raw header length in JSON from ElectrumX blockchain.block.headers RPC");
}
return rawBlockHeaders; return rawBlockHeaders;
} }