Use bytes to represent memo text

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 As this project is pre 1.0, breaking changes may happen for minor version bumps. A breaking change will get clearly notified in this log.
 
+## 0.12.0
+
+* Represent memo text contents as bytes because a memo text may not be valid UTF-8 string (https://github.com/stellar/java-stellar-sdk/issues/257).
+
 ## 0.11.0
 
 * Fix bug in `org.stellar.sdk.requests.OperationsRequestBuilder.operation(long operationId)`. The method submitted an HTTP request to Horizon with the following path, /operation/<id> , but the correct path is /operations/<id>

build.gradle

@@ -16,7 +16,7 @@ apply plugin: 'com.github.ben-manes.versions' // gradle dependencyUpdates -Drevi
 apply plugin: 'project-report' // gradle htmlDependencyReport
 
 sourceCompatibility = 1.6
-version = '0.11.0'
+version = '0.12.0'
 group = 'stellar'
 
 jar {

src/main/java/org/stellar/sdk/Memo.java

@@ -30,6 +30,15 @@ public static MemoText text(String text) {
         return new MemoText(text);
     }
 
+    /**
+     * Creates new {@link MemoText} instance.
+     * @param text
+     */
+    public static MemoText text(byte[] text) {
+        return new MemoText(text);
+    }
+
+
     /**
      * Creates new {@link MemoId} instance.
      * @param id

src/main/java/org/stellar/sdk/MemoText.java

@@ -4,26 +4,33 @@
 import org.stellar.sdk.xdr.MemoType;
 
 import java.nio.charset.Charset;
+import java.util.Arrays;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * Represents MEMO_TEXT.
  */
 public class MemoText extends Memo {
-  private String text;
+  private byte[] text;
 
   public MemoText(String text) {
-    this.text = checkNotNull(text, "text cannot be null");
+    this(checkNotNull(text, "text cannot be null").getBytes((Charset.forName("UTF-8"))));
+  }
 
-    int length = text.getBytes((Charset.forName("UTF-8"))).length;
-    if (length > 28) {
-      throw new MemoTooLongException("text must be <= 28 bytes. length=" + String.valueOf(length));
+  public MemoText(byte[] text) {
+    this.text = checkNotNull(text, "text cannot be null");
+    if (this.text.length > 28) {
+      throw new MemoTooLongException("text must be <= 28 bytes. length=" + String.valueOf(this.text.length));
     }
   }
 
   public String getText() {
-    return text;
+    return new String(this.text, Charset.forName("UTF-8"));
+  }
+
+  public byte[] getBytes() {
+    return this.text;
   }
 
   @Override
@@ -36,19 +43,19 @@ org.stellar.sdk.xdr.Memo toXdr() {
 
   @Override
   public int hashCode() {
-    return Objects.hashCode(this.text);
+    return Arrays.hashCode(this.text);
   }
 
   @Override
   public boolean equals(Object o) {
     if (this == o) return true;
     if (o == null || getClass() != o.getClass()) return false;
     MemoText memoText = (MemoText) o;
-    return Objects.equal(this.text, memoText.text);
+    return Arrays.equals(this.text, memoText.text);
   }
 
     @Override
     public String toString() {
-        return text == null ? "" : text;
+        return text == null ? "" : this.getText();
     }
 }

src/main/java/org/stellar/sdk/responses/TransactionDeserializer.java

@@ -9,7 +9,11 @@
 import com.google.gson.JsonParseException;
 
 import org.stellar.sdk.Memo;
+import org.stellar.sdk.xdr.TransactionEnvelope;
+import org.stellar.sdk.xdr.XdrDataInputStream;
 
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
 import java.lang.reflect.Type;
 
 public class TransactionDeserializer implements JsonDeserializer<TransactionResponse> {
@@ -31,12 +35,19 @@ public TransactionResponse deserialize(JsonElement json, Type typeOfT, JsonDeser
       // representation of a transaction. That's why we need to handle a special case
       // here.
       if (memoType.equals("text")) {
-        JsonElement memoField = json.getAsJsonObject().get("memo");
-        if (memoField != null) {
-          memo = Memo.text(memoField.getAsString());
-        } else {
-          memo = Memo.text("");
+        // we obtain the memo text from the xdr because the bytes may not be valid utf8
+        String envelopeXdr = json.getAsJsonObject().get("envelope_xdr").getAsString();
+        BaseEncoding base64Encoding = BaseEncoding.base64();
+        byte[] bytes = base64Encoding.decode(envelopeXdr);
+        TransactionEnvelope transactionEnvelope = null;
+        try {
+          transactionEnvelope = TransactionEnvelope.decode(new XdrDataInputStream(new ByteArrayInputStream(bytes)));
+        } catch (IOException e) {
+          // JsonDeserializer<TransactionResponse> cannot throw IOExceptions
+          // so we must throw it as a runtime exception
+          throw new RuntimeException(e);
         }
+        memo = Memo.text(transactionEnvelope.getTx().getMemo().getText());
       } else {
         String memoValue = json.getAsJsonObject().get("memo").getAsString();
         BaseEncoding base64Encoding = BaseEncoding.base64();

src/main/java/org/stellar/sdk/xdr/Memo.java

@@ -7,6 +7,7 @@
 import java.io.IOException;
 
 import com.google.common.base.Objects;
+import java.util.Arrays;
 
 // === xdr source ============================================================
 
@@ -15,7 +16,7 @@
 //  case MEMO_NONE:
 //      void;
 //  case MEMO_TEXT:
-//      string text<28>;
+//      opaque text<28>;
 //  case MEMO_ID:
 //      uint64 id;
 //  case MEMO_HASH:
@@ -34,11 +35,11 @@ public MemoType getDiscriminant() {
   public void setDiscriminant(MemoType value) {
     this.type = value;
   }
-  private String text;
-  public String getText() {
+  private byte[] text;
+  public byte[] getText() {
     return this.text;
   }
-  public void setText(String value) {
+  public void setText(byte[] value) {
     this.text = value;
   }
   private Uint64 id;
@@ -70,7 +71,9 @@ public static void encode(XdrDataOutputStream stream, Memo encodedMemo) throws I
   case MEMO_NONE:
   break;
   case MEMO_TEXT:
-  stream.writeString(encodedMemo.text);
+  int textsize = encodedMemo.text.length;
+  stream.writeInt(textsize);
+  stream.write(encodedMemo.getText(), 0, textsize);
   break;
   case MEMO_ID:
   Uint64.encode(stream, encodedMemo.id);
@@ -94,7 +97,9 @@ public static Memo decode(XdrDataInputStream stream) throws IOException {
   case MEMO_NONE:
   break;
   case MEMO_TEXT:
-  decodedMemo.text = stream.readString();
+  int textsize = stream.readInt();
+  decodedMemo.text = new byte[textsize];
+  stream.read(decodedMemo.text, 0, textsize);
   break;
   case MEMO_ID:
   decodedMemo.id = Uint64.decode(stream);
@@ -110,7 +115,7 @@ public static Memo decode(XdrDataInputStream stream) throws IOException {
   }
   @Override
   public int hashCode() {
-    return Objects.hashCode(this.text, this.id, this.hash, this.retHash, this.type);
+    return Objects.hashCode(Arrays.hashCode(this.text), this.id, this.hash, this.retHash, this.type);
   }
   @Override
   public boolean equals(Object object) {
@@ -119,6 +124,6 @@ public boolean equals(Object object) {
     }
 
     Memo other = (Memo) object;
-    return Objects.equal(this.text, other.text) && Objects.equal(this.id, other.id) && Objects.equal(this.hash, other.hash) && Objects.equal(this.retHash, other.retHash) && Objects.equal(this.type, other.type);
+    return Arrays.equals(this.text, other.text) && Objects.equal(this.id, other.id) && Objects.equal(this.hash, other.hash) && Objects.equal(this.retHash, other.retHash) && Objects.equal(this.type, other.type);
   }
 }

src/test/java/org/stellar/sdk/xdr/TransactionDecodeTest.java

@@ -2,8 +2,11 @@
 
 import com.google.common.io.BaseEncoding;
 import org.junit.Test;
+import org.stellar.sdk.Memo;
+import org.stellar.sdk.MemoText;
 
 import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.util.Arrays;
 
@@ -59,4 +62,19 @@ public void testTransactionEnvelopeWithMemo() throws IOException {
         assertTrue(Arrays.equals(new byte[]{'G', 'O', 'L', 'D'}, transactionEnvelope.getTx().getOperations()[0].getBody().getPaymentOp().getAsset().getAlphaNum4().getAssetCode().getAssetCode4()));
     }
 
+    @Test
+    public void testRoundtrip() throws IOException {
+        String txBody = "AAAAAM6jLgjKjuXxWkir4M7v0NqoOfODXcFnn6AGlP+d4RxAAAAAZAAIiE4AAAABAAAAAAAAAAEAAAAcyKMl+WDSzuttWkF2DvzKAkkEqeSZ4cZihjGJEAAAAAEAAAAAAAAAAQAAAAAgECmBaDwiRPE1z2vAE36J+45toU/ZxdvpR38tc0HvmgAAAAAAAAAAAJiWgAAAAAAAAAABneEcQAAAAECeXDKebJoAbST1T2AbDBui9K0TbSM8sfbhXUAZ2ROAoCRs5cG1pRvY+ityyPWFEKPd7+3qEupavkAZ/+L7/28G";
+        BaseEncoding base64Encoding = BaseEncoding.base64();
+        byte[] bytes = base64Encoding.decode(txBody);
+
+        TransactionEnvelope transactionEnvelope = TransactionEnvelope.decode(new XdrDataInputStream(new ByteArrayInputStream(bytes)));
+        ByteArrayOutputStream byteOutputStream = new ByteArrayOutputStream();
+
+        transactionEnvelope.encode(new XdrDataOutputStream(byteOutputStream));
+        String serialized = base64Encoding.encode(byteOutputStream.toByteArray());
+        // fails here
+        assertEquals(serialized, txBody);
+    }
+
 }

xdr/Stellar-transaction.x

@@ -335,7 +335,7 @@ union Memo switch (MemoType type)
 case MEMO_NONE:
     void;
 case MEMO_TEXT:
-    string text<28>;
+    opaque text<28>;
 case MEMO_ID:
     uint64 id;
 case MEMO_HASH: