Update justification verification (#727)

# Description

- JustificationVerifier.verify() method now has Justification as an
input parameter and also executes block ancestry validation
- JustificationVerifier.verify() method checks if there are more than 3
votes cast by single authority. The vote with the smaller block number
is considered as the valid vote, other two are counted as equivocations.
- Replace PreCommit with SignedVote in all places and delete PreCommit
object

Fixes: #655 &
#648

src/main/java/com/limechain/grandpa/GrandpaService.java

@@ -14,7 +14,6 @@
 import com.limechain.network.protocol.grandpa.messages.vote.SignedMessage;
 import com.limechain.network.protocol.grandpa.messages.vote.VoteMessage;
 import com.limechain.network.protocol.warp.dto.BlockHeader;
-import com.limechain.network.protocol.warp.dto.PreCommit;
 import com.limechain.state.AbstractState;
 import com.limechain.state.StateManager;
 import com.limechain.storage.block.state.BlockState;
@@ -478,16 +477,13 @@ private List<Vote> getBlockDescendents(Vote vote, List<Vote> votes) {
      * 2. During attempt-to-finalize, broadcasting a commit message for the best candidate block of the current round.
      */
     private void broadcastCommitMessage(GrandpaRound grandpaRound) {
-        PreCommit[] precommits = transformToCompactJustificationFormat(grandpaRound.getPreCommits());
+        SignedVote[] preCommits = grandpaRound.getPreCommits().values().toArray(new SignedVote[0]);
 
         CommitMessage commitMessage = new CommitMessage();
         commitMessage.setSetId(stateManager.getGrandpaSetState().getSetId());
         commitMessage.setRoundNumber(grandpaRound.getRoundNumber());
-        commitMessage.setVote(
-                toVote(
-                        grandpaRound.getBestFinalCandidate()
-                ));
-        commitMessage.setPreCommits(precommits);
+        commitMessage.setVote(toVote(grandpaRound.getBestFinalCandidate()));
+        commitMessage.setPreCommits(preCommits);
 
         peerMessageCoordinator.sendCommitMessageToPeers(commitMessage);
     }
@@ -529,18 +525,6 @@ public void broadcastPreVoteMessage(GrandpaRound grandpaRound) {
         peerMessageCoordinator.sendVoteMessageToPeers(voteMessage);
     }
 
-    private PreCommit[] transformToCompactJustificationFormat(Map<Hash256, SignedVote> signedVotes) {
-        return signedVotes.values().stream()
-                .map(signedVote -> {
-                    PreCommit precommit = new PreCommit();
-                    precommit.setTargetHash(signedVote.getVote().getBlockHash());
-                    precommit.setTargetNumber(signedVote.getVote().getBlockNumber());
-                    precommit.setSignature(signedVote.getSignature());
-                    precommit.setAuthorityPublicKey(signedVote.getAuthorityPublicKey());
-                    return precommit;
-                }).toArray(PreCommit[]::new);
-    }
-
     private Vote toVote(BlockHeader blockHeader) {
         Vote vote = new Vote();
         vote.setBlockHash(blockHeader.getHash());

src/main/java/com/limechain/network/protocol/grandpa/messages/commit/CommitMessage.java

@@ -1,7 +1,7 @@
 package com.limechain.network.protocol.grandpa.messages.commit;
 
+import com.limechain.grandpa.vote.SignedVote;
 import com.limechain.grandpa.vote.Vote;
-import com.limechain.network.protocol.warp.dto.PreCommit;
 import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.NoArgsConstructor;
@@ -15,5 +15,5 @@ public class CommitMessage {
     private BigInteger roundNumber;
     private BigInteger setId;
     private Vote vote;
-    private PreCommit[] preCommits;
+    private SignedVote[] preCommits;
 }

src/main/java/com/limechain/network/protocol/grandpa/messages/commit/CompactJustificationScaleReader.java

@@ -1,8 +1,8 @@
 package com.limechain.network.protocol.grandpa.messages.commit;
 
 import com.limechain.exception.network.SignatureCountMismatchException;
+import com.limechain.grandpa.vote.SignedVote;
 import com.limechain.grandpa.vote.Vote;
-import com.limechain.network.protocol.warp.dto.PreCommit;
 import io.emeraldpay.polkaj.scale.ScaleCodecReader;
 import io.emeraldpay.polkaj.scale.ScaleReader;
 import io.emeraldpay.polkaj.scale.reader.ListReader;
@@ -11,7 +11,7 @@
 
 import java.util.List;
 
-public class CompactJustificationScaleReader implements ScaleReader<PreCommit[]> {
+public class CompactJustificationScaleReader implements ScaleReader<SignedVote[]> {
 
     private static final CompactJustificationScaleReader INSTANCE = new CompactJustificationScaleReader();
 
@@ -27,17 +27,15 @@ public static CompactJustificationScaleReader getInstance() {
     }
 
     @Override
-    public PreCommit[] read(ScaleCodecReader reader) {
+    public SignedVote[] read(ScaleCodecReader reader) {
         List<Vote> votes = voteListReader.read(reader);
 
         int preCommitsCount = votes.size();
-        PreCommit[] preCommits = new PreCommit[preCommitsCount];
+        SignedVote[] preCommits = new SignedVote[preCommitsCount];
 
         for (int i = 0; i < preCommitsCount; i++) {
-            Vote vote = votes.get(i);
-            preCommits[i] = new PreCommit();
-            preCommits[i].setTargetHash(vote.getBlockHash());
-            preCommits[i].setTargetNumber(vote.getBlockNumber());
+            preCommits[i] = new SignedVote();
+            preCommits[i].setVote(votes.get(i));
         }
 
         int signaturesCount = reader.readCompactInt();

src/main/java/com/limechain/network/protocol/grandpa/messages/commit/CompactJustificationScaleWriter.java

@@ -1,13 +1,12 @@
 package com.limechain.network.protocol.grandpa.messages.commit;
 
-import com.limechain.grandpa.vote.Vote;
-import com.limechain.network.protocol.warp.dto.PreCommit;
+import com.limechain.grandpa.vote.SignedVote;
 import io.emeraldpay.polkaj.scale.ScaleCodecWriter;
 import io.emeraldpay.polkaj.scale.ScaleWriter;
 
 import java.io.IOException;
 
-public class CompactJustificationScaleWriter implements ScaleWriter<PreCommit[]> {
+public class CompactJustificationScaleWriter implements ScaleWriter<SignedVote[]> {
 
     private static final CompactJustificationScaleWriter INSTANCE = new CompactJustificationScaleWriter();
 
@@ -22,21 +21,16 @@ public static CompactJustificationScaleWriter getInstance() {
     }
 
     @Override
-    public void write(ScaleCodecWriter writer, PreCommit[] preCommits) throws IOException {
+    public void write(ScaleCodecWriter writer, SignedVote[] preCommits) throws IOException {
         writer.writeCompact(preCommits.length);
 
-        for (int i = 0; i < preCommits.length; i++) {
-            PreCommit preCommit = preCommits[i];
-            Vote vote = new Vote();
-            vote.setBlockHash(preCommit.getTargetHash());
-            vote.setBlockNumber(preCommit.getTargetNumber());
-            voteScaleWriter.write(writer, vote);
+        for (SignedVote preCommit : preCommits) {
+            voteScaleWriter.write(writer, preCommit.getVote());
         }
 
         writer.writeCompact(preCommits.length);
 
-        for (int i = 0; i < preCommits.length; i++) {
-            PreCommit preCommit = preCommits[i];
+        for (SignedVote preCommit : preCommits) {
             writer.writeByteArray(preCommit.getSignature().getBytes());
             writer.writeUint256(preCommit.getAuthorityPublicKey().getBytes());
         }

src/main/java/com/limechain/network/protocol/warp/dto/Justification.java

@@ -1,31 +1,40 @@
 package com.limechain.network.protocol.warp.dto;
 
+import com.limechain.grandpa.vote.SignedVote;
+import com.limechain.network.protocol.grandpa.messages.commit.CommitMessage;
 import io.emeraldpay.polkaj.types.Hash256;
 import lombok.Getter;
 import lombok.Setter;
-import lombok.extern.java.Log;
 
 import java.math.BigInteger;
 import java.util.Arrays;
 
 @Setter
 @Getter
-@Log
 public class Justification {
 
-    private BigInteger round;
+    private BigInteger roundNumber;
     private Hash256 targetHash;
     private BigInteger targetBlock;
-    private PreCommit[] preCommits;
+    private SignedVote[] signedVotes; // either preCommis or preVotes
     private BlockHeader[] ancestryVotes;
 
+    public static Justification fromCommitMessage(CommitMessage commitMessage) {
+        Justification justification = new Justification();
+        justification.setRoundNumber(commitMessage.getRoundNumber());
+        justification.setTargetHash(commitMessage.getVote().getBlockHash());
+        justification.setTargetBlock(commitMessage.getVote().getBlockNumber());
+        justification.setSignedVotes(commitMessage.getPreCommits());
+        return justification;
+    }
+
     @Override
     public String toString() {
-        return "WarpSyncJustification{" +
-                "round=" + round +
+        return "Justification{" +
+                "roundNumber=" + roundNumber +
                 ", targetHash=" + targetHash +
                 ", targetBlock=" + targetBlock +
-                ", preCommits=" + Arrays.toString(preCommits) +
+                ", signedVotes=" + Arrays.toString(signedVotes) +
                 ", ancestryVotes=" + Arrays.toString(ancestryVotes) +
                 '}';
     }

src/main/java/com/limechain/network/protocol/warp/scale/reader/JustificationReader.java

@@ -1,8 +1,9 @@
 package com.limechain.network.protocol.warp.scale.reader;
 
+import com.limechain.grandpa.vote.SignedVote;
+import com.limechain.network.protocol.grandpa.messages.catchup.res.SignedVoteScaleReader;
 import com.limechain.network.protocol.warp.dto.BlockHeader;
 import com.limechain.network.protocol.warp.dto.Justification;
-import com.limechain.network.protocol.warp.dto.PreCommit;
 import io.emeraldpay.polkaj.scale.ScaleCodecReader;
 import io.emeraldpay.polkaj.scale.ScaleReader;
 import io.emeraldpay.polkaj.scale.reader.UInt64Reader;
@@ -22,20 +23,20 @@ public static JustificationReader getInstance() {
     @Override
     public Justification read(ScaleCodecReader reader) {
         Justification justification = new Justification();
-        justification.setRound(new UInt64Reader().read(reader));
+        justification.setRoundNumber(new UInt64Reader().read(reader));
 
         // Target hash and target block constitute the "GRANDPA Vote":
         // https://spec.polkadot.network/sect-finality#defn-vote
         justification.setTargetHash(new Hash256(reader.readUint256()));
         justification.setTargetBlock(BlockNumberReader.getInstance().read(reader));
 
-        int preCommitsCount = reader.readCompactInt();
-        PreCommit[] preCommits = new PreCommit[preCommitsCount];
-        PreCommitReader preCommitReader = PreCommitReader.getInstance();
-        for (int i = 0; i < preCommitsCount; i++) {
-            preCommits[i] = preCommitReader.read(reader);
+        int signedVotesCount = reader.readCompactInt();
+        SignedVote[] signedVotes = new SignedVote[signedVotesCount];
+        SignedVoteScaleReader signedVoteReader = SignedVoteScaleReader.getInstance();
+        for (int i = 0; i < signedVotesCount; i++) {
+            signedVotes[i] = signedVoteReader.read(reader);
         }
-        justification.setPreCommits(preCommits);
+        justification.setSignedVotes(signedVotes);
 
         int ancestryCount = reader.readCompactInt();
         BlockHeader[] ancestries = new BlockHeader[ancestryCount];