From 438cc590f616a68d478a9c01a6749fdbafb7c6d7 Mon Sep 17 00:00:00 2001
From: Peter Fox <peter.rd.fox@gmail.com>
Date: Thu, 18 Oct 2018 15:55:06 +0100
Subject: [PATCH] When decoding a payload that has no recipients, return an
 empty list without further inspection of the byte buffer.

This reduces the need to calling methods to determine ahead of time
which of the decode methods should be called.
---
 .../transaction/PayloadEncoderImpl.java       |  5 ++++
 .../transaction/PayloadEncoderTest.java       | 25 +++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/tessera-core/src/main/java/com/quorum/tessera/transaction/PayloadEncoderImpl.java b/tessera-core/src/main/java/com/quorum/tessera/transaction/PayloadEncoderImpl.java
index dacf203555..f468f496cf 100644
--- a/tessera-core/src/main/java/com/quorum/tessera/transaction/PayloadEncoderImpl.java
+++ b/tessera-core/src/main/java/com/quorum/tessera/transaction/PayloadEncoderImpl.java
@@ -127,6 +127,11 @@ public EncodedPayloadWithRecipients decodePayloadWithRecipients(final byte[] inp
                 new Nonce(recipientNonce)
         );
 
+        //this means there are no recipients in the payload (which we receive when we are a participant)
+        if (!buffer.hasRemaining()) {
+            return new EncodedPayloadWithRecipients(payload, emptyList());
+        }
+
         final long recipientLength = buffer.getLong();
 
         final List<byte[]> recipientKeys = new ArrayList<>();
diff --git a/tessera-core/src/test/java/com/quorum/tessera/transaction/PayloadEncoderTest.java b/tessera-core/src/test/java/com/quorum/tessera/transaction/PayloadEncoderTest.java
index 070fff2b33..d8ef4520ae 100644
--- a/tessera-core/src/test/java/com/quorum/tessera/transaction/PayloadEncoderTest.java
+++ b/tessera-core/src/test/java/com/quorum/tessera/transaction/PayloadEncoderTest.java
@@ -179,4 +179,29 @@ public void decodePayloadWithRecipients() {
         assertThat(result.getEncodedPayload().getRecipientBoxes()).isNotEqualTo(control.getEncodedPayload().getRecipientBoxes());
     }
 
+    @Test
+    public void decodeWithNoRecipientsGivesEmptyList() {
+
+        final byte[] input = new byte[]{0, 0, 0, 0, 0, 0, 0, 32, -51, 40, -97, 78, 121, 47, -26, -66, 10, -21, -80, -22, -33, 78, 30, 85, -61, 56, 22, -100, 70, 124, 114, -34, -41, 36, -62, 6, 109, 63, -17, 8, 0, 0, 0, 0, 0, 0, 0, 28, 120, 111, 63, -100, 97, -12, -103, 20, 2, -48, 37, -86, -115, -112, -75, -27, 55, 12, -1, 120, 13, 0, 86, 92, 52, 77, -4, 45, 0, 0, 0, 0, 0, 0, 0, 24, -115, -84, -58, 14, 82, 118, 4, -118, -53, 86, 3, 14, 112, 70, -4, 81, 121, 84, -24, -3, -73, -17, 6, 124, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 48, -87, -102, 0, 95, -13, 48, 76, -115, -115, 62, 54, -55, -78, 125, -54, -34, -71, -11, -95, -85, 78, -24, -30, 47, 65, 5, 88, 38, -111, -12, -41, -97, 103, -60, -101, 43, -57, -68, 68, -109, 36, 49, -63, -123, 62, 21, 67, -28, 0, 0, 0, 0, 0, 0, 0, 24, -63, 5, 86, 42, -85, -12, -36, 16, -108, 48, 26, 36, 44, -82, 15, -38, -19, 6, -101, 107, 110, -30, 95, 5};
+
+        final byte[] senderKey = new byte[]{-51, 40, -97, 78, 121, 47, -26, -66, 10, -21, -80, -22, -33, 78, 30, 85, -61, 56, 22, -100, 70, 124, 114, -34, -41, 36, -62, 6, 109, 63, -17, 8};
+        final byte[] ciphertext = new byte[]{120, 111, 63, -100, 97, -12, -103, 20, 2, -48, 37, -86, -115, -112, -75, -27, 55, 12, -1, 120, 13, 0, 86, 92, 52, 77, -4, 45};
+        final byte[] nonce = new byte[]{-115, -84, -58, 14, 82, 118, 4, -118, -53, 86, 3, 14, 112, 70, -4, 81, 121, 84, -24, -3, -73, -17, 6, 124};
+        final byte[] recipientnonce = new byte[]{-63, 5, 86, 42, -85, -12, -36, 16, -108, 48, 26, 36, 44, -82, 15, -38, -19, 6, -101, 107, 110, -30, 95, 5};
+        final byte[] recipient = new byte[]{-87, -102, 0, 95, -13, 48, 76, -115, -115, 62, 54, -55, -78, 125, -54, -34, -71, -11, -95, -85, 78, -24, -30, 47, 65, 5, 88, 38, -111, -12, -41, -97, 103, -60, -101, 43, -57, -68, 68, -109, 36, 49, -63, -123, 62, 21, 67, -28};
+
+        final EncodedPayloadWithRecipients encodedPayloadWithRecipients = payloadEncoder.decodePayloadWithRecipients(input);
+        final EncodedPayload encodedPayload = encodedPayloadWithRecipients.getEncodedPayload();
+
+        assertThat(encodedPayloadWithRecipients.getRecipientKeys()).isEmpty();
+
+        assertThat(encodedPayload.getSenderKey()).isEqualTo(PublicKey.from(senderKey));
+        assertThat(encodedPayload.getCipherText()).containsExactly(ciphertext);
+        assertThat(encodedPayload.getCipherTextNonce()).isEqualTo(new Nonce(nonce));
+        assertThat(encodedPayload.getRecipientNonce()).isEqualTo(new Nonce(recipientnonce));
+        assertThat(encodedPayload.getRecipientBoxes()).hasSize(1);
+        assertThat(encodedPayload.getRecipientBoxes().get(0)).containsExactly(recipient);
+
+    }
+
 }