#68 Allow custom network ID

Author: martti007

src/main/java/org/unicitylabs/sdk/api/NetworkId.java

@@ -3,19 +3,44 @@
 /**
  * Unicity network identifier ({@code α}). Used to scope token ids and other
  * network-bound values so they cannot be replayed across networks.
- *
- * <p>{@code 0} is reserved as an uninitialized sentinel and is rejected by
- * {@link #fromId(short)}.
  */
-public enum NetworkId {
-  MAINNET((short) 1),
-  TESTNET((short) 2),
-  LOCAL((short) 3);
+public final class NetworkId {
+
+  public static final NetworkId MAINNET = new NetworkId((short) 1, "MAINNET");
+  public static final NetworkId TESTNET = new NetworkId((short) 2, "TESTNET");
+  public static final NetworkId LOCAL = new NetworkId((short) 3, "LOCAL");
 
   private final short id;
+  private final String name;
 
-  NetworkId(short id) {
+  private NetworkId(short id, String name) {
     this.id = id;
+    this.name = name;
+  }
+
+  private NetworkId(short id) {
+    this(id, null);
+  }
+
+  /**
+   * Resolve a NetworkId from its numeric identifier. Returns the registered
+   * singleton for known ids; constructs a new (unnamed) instance for any
+   * other 16-bit value.
+   *
+   * @param id numeric network identifier
+   * @return NetworkId for the given identifier
+   */
+  public static NetworkId fromId(short id) {
+    if (id == MAINNET.id) {
+      return MAINNET;
+    }
+    if (id == TESTNET.id) {
+      return TESTNET;
+    }
+    if (id == LOCAL.id) {
+      return LOCAL;
+    }
+    return new NetworkId(id);
   }
 
   /**
@@ -27,19 +52,24 @@ public short getId() {
     return this.id;
   }
 
-  /**
-   * Look up a NetworkId by its numeric identifier.
-   *
-   * @param id numeric network identifier
-   * @return matching network identifier
-   * @throws IllegalArgumentException if {@code id} is not a registered network
-   */
-  public static NetworkId fromId(short id) {
-    for (NetworkId network : NetworkId.values()) {
-      if (network.id == id) {
-        return network;
-      }
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
     }
-    throw new IllegalArgumentException("Unknown network identifier: " + id);
+    if (!(o instanceof NetworkId)) {
+      return false;
+    }
+    return this.id == ((NetworkId) o).id;
+  }
+
+  @Override
+  public int hashCode() {
+    return Short.hashCode(this.id);
+  }
+
+  @Override
+  public String toString() {
+    return "NetworkId[" + (this.name != null ? this.name : this.id) + "]";
   }
-}
+}

src/main/java/org/unicitylabs/sdk/api/bft/verification/UnicityCertificateVerification.java

@@ -29,7 +29,7 @@ public static UnicityCertificateVerificationResult verify(RootTrustBase trustBas
                                                             InclusionProof inclusionProof) {
     ArrayList<VerificationResult<?>> results = new ArrayList<>();
 
-    if (inclusionProof.getUnicityCertificate().getUnicitySeal().getNetworkId() != trustBase.getNetworkId()) {
+    if (!inclusionProof.getUnicityCertificate().getUnicitySeal().getNetworkId().equals(trustBase.getNetworkId())) {
       results.add(new VerificationResult<>("UnicitySealNetworkMatchesTrustBaseRule", VerificationStatus.FAIL));
       return UnicityCertificateVerificationResult.fail(results);
     }

src/main/java/org/unicitylabs/sdk/payment/SplitMintJustificationVerifier.java

@@ -1,5 +1,6 @@
 package org.unicitylabs.sdk.payment;
 
+import org.unicitylabs.sdk.api.NetworkId;
 import org.unicitylabs.sdk.api.bft.RootTrustBase;
 import org.unicitylabs.sdk.crypto.hash.DataHash;
 import org.unicitylabs.sdk.payment.asset.Asset;
@@ -69,6 +70,19 @@ public VerificationResult<VerificationStatus> verify(CertifiedMintTransaction tr
       );
     }
 
+    NetworkId sourceNetworkId = justification.getToken().getGenesis().getNetworkId();
+    if (!transaction.getNetworkId().equals(sourceNetworkId)) {
+      return new VerificationResult<>(
+              "SplitMintJustificationVerificationRule",
+              VerificationStatus.FAIL,
+              String.format(
+                      "Network identifier mismatch: mint is on %s, source token is on %s.",
+                      transaction.getNetworkId(),
+                      sourceNetworkId
+              )
+      );
+    }
+
     VerificationResult<VerificationStatus> verificationResult = justification.getToken()
             .verify(trustBase, predicateVerifier, mintJustificationVerifier);
     if (verificationResult.getStatus() != VerificationStatus.OK) {

src/main/java/org/unicitylabs/sdk/payment/TokenSplit.java

@@ -20,7 +20,6 @@
 import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;

src/main/java/org/unicitylabs/sdk/transaction/verification/CertifiedMintTransactionVerificationRule.java

@@ -44,7 +44,7 @@ public static VerificationResult<VerificationStatus> verify(
   ) {
     List<VerificationResult<?>> results = new ArrayList<>();
 
-    if (transaction.getNetworkId() != trustBase.getNetworkId()) {
+    if (!transaction.getNetworkId().equals(trustBase.getNetworkId())) {
       results.add(new VerificationResult<>("MintNetworkMatchesTrustBaseRule", VerificationStatus.FAIL));
       return new VerificationResult<>("CertifiedMintTransactionVerificationRule",
               VerificationStatus.FAIL, "Mint network does not match trust base.", results);

src/test/java/org/unicitylabs/sdk/utils/TokenUtils.java

@@ -33,7 +33,7 @@ public static Token mintToken(
           Predicate recipient
   ) throws Exception {
     return TokenUtils.mintToken(client, trustBase, predicateVerifier, mintJustificationVerifier,
-            recipient, null);
+            recipient, (byte[]) null);
   }
 
   public static Token mintToken(