Added util class for processing name transactions.

core/src/main/java/org/libdohj/names/NameTransactionUtils.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2016 Jeremy Rand.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.libdohj.names;
+
+import org.libdohj.script.NameScript;
+
+import org.bitcoinj.core.ScriptException;
+import org.bitcoinj.core.Transaction;
+import org.bitcoinj.core.TransactionOutput;
+import org.bitcoinj.script.Script;
+
+import java.io.UnsupportedEncodingException;
+
+// TODO: document this
+
+// TODO: look into allowing name and value to be ArrayList<byte> as an alternative to String.
+
+public class NameTransactionUtils {
+    
+    // Providing the name is, in theory, superfluous, since only 1 name output can exist per transaction.
+    // However, this might be changed in the future, to allow atomic updates of multiple names.
+    // This could enable things like CoinJoin for names.
+    public static TransactionOutput getNameAnyUpdateOutput(Transaction tx, String name) {
+        for (TransactionOutput output : tx.getOutputs()) {
+            try {
+                Script scriptPubKey = output.getScriptPubKey();
+                NameScript ns = new NameScript(scriptPubKey);
+                if(ns.isNameOp() && ns.isAnyUpdate() && new String(ns.getOpName().data, "ISO-8859-1").equals(name)) {
+                    return output;
+                }
+            } catch (ScriptException e) {
+                continue;
+            } catch (UnsupportedEncodingException e) {
+                continue;
+            }
+        }
+        
+        // No such output was found.
+        return null;
+    }
+    
+    public static NameScript getNameAnyUpdateScript(Transaction tx, String name) {
+        TransactionOutput output = getNameAnyUpdateOutput(tx, name);
+        
+        if (output == null) {
+            return null;
+        }
+        
+        Script scriptPubKey = output.getScriptPubKey();
+        return new NameScript(scriptPubKey);
+    }
+    
+    public static String getNameValueAsString(Transaction tx, String name) throws UnsupportedEncodingException {
+        NameScript ns = getNameAnyUpdateScript(tx, name);
+        
+        if (ns == null) {
+            return null;
+        }
+        
+        return new String(ns.getOpValue().data, "ISO-8859-1");
+    }
+}