From 6ba301b6b825697b1157693b2541a3371975cc9e Mon Sep 17 00:00:00 2001
From: jamescarlyle <james@r3cev.com>
Date: Fri, 19 Aug 2016 17:45:25 +0100
Subject: [PATCH] Updated based on feedback to check that the encumbered state
 does not refer to itself as the encumbrance.

---
 .../core/contracts/TransactionTypes.kt        | 12 +++++++-
 .../contracts/TransactionEncumbranceTests.kt  | 29 +++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/core/src/main/kotlin/com/r3corda/core/contracts/TransactionTypes.kt b/core/src/main/kotlin/com/r3corda/core/contracts/TransactionTypes.kt
index 994f1e2de6..c7ead96939 100644
--- a/core/src/main/kotlin/com/r3corda/core/contracts/TransactionTypes.kt
+++ b/core/src/main/kotlin/com/r3corda/core/contracts/TransactionTypes.kt
@@ -81,11 +81,21 @@ sealed class TransactionType {
             // Validate that all encumbrances exist within the set of input states.
             tx.inputs.filter { it.state.data.encumbrance != null }.forEach {
                 encumberedInput ->
-                if (tx.inputs.none { it.ref.txhash == encumberedInput.ref.txhash && it.ref.index == encumberedInput.state.data.encumbrance }) {
+                if (tx.inputs.none { it.ref.txhash == encumberedInput.ref.txhash &&
+                        it.ref.index == encumberedInput.state.data.encumbrance }) {
                     throw TransactionVerificationException.TransactionMissingEncumbranceException(tx)
                 }
             }
 
+            // Check that an encumbered state does not refer to itself as the encumbrance, and that the number of outputs
+            // can contain the encumbrance.
+            tx.outputs.forEachIndexed { i, it ->
+                if (it.data.encumbrance != null) {
+                    if (it.data.encumbrance == i || it.data.encumbrance!! >= tx.outputs.size) {
+                        throw TransactionVerificationException.TransactionMissingEncumbranceException(tx)
+                    }
+                }
+            }
         }
 
         override fun getRequiredSigners(tx: LedgerTransaction) = tx.commands.flatMap { it.signers }.toSet()
diff --git a/core/src/test/kotlin/com/r3corda/core/contracts/TransactionEncumbranceTests.kt b/core/src/test/kotlin/com/r3corda/core/contracts/TransactionEncumbranceTests.kt
index 87b6d1187b..b6f1a52c9f 100644
--- a/core/src/test/kotlin/com/r3corda/core/contracts/TransactionEncumbranceTests.kt
+++ b/core/src/test/kotlin/com/r3corda/core/contracts/TransactionEncumbranceTests.kt
@@ -67,6 +67,35 @@ class TransactionEncumbranceTests {
                 this.verifies()
             }
         }
+        // An encumbered state must not be encumbered by itself.
+        assertFailsWith(TransactionVerificationException.TransactionMissingEncumbranceException::class) {
+            transaction {
+                input { unencumberedState }
+                input { unencumberedState }
+                output { unencumberedState }
+                // The encumbered state refers to an encumbrance in position 1, so what follows is wrong.
+                output { encumberedState }
+                command(DUMMY_PUBKEY_1) { Cash.Commands.Move() }
+                this.verifies()
+            }
+        }
+        // An encumbered state must not reference an index greater than the size of the output states.
+        assertFailsWith(TransactionVerificationException.TransactionMissingEncumbranceException::class) {
+            transaction {
+                input { unencumberedState }
+                input { unencumberedState }
+                output { unencumberedState }
+                // The encumbered state refers to an encumbrance in position 1, so what follows is wrong.
+                output { encumberedState }
+                command(DUMMY_PUBKEY_1) { Cash.Commands.Move() }
+                this.verifies()
+            }
+        }
+
+    }
+
+    @Test
+    fun testEncumbranceEffects() {
         // A transaction containing an input state that is encumbered must fail if the encumbrance is not in the correct position.
         assertFailsWith(TransactionVerificationException.TransactionMissingEncumbranceException::class) {
             ledger {