From 36df92f8ad0ca049d934e06ca44b4553ec10ea36 Mon Sep 17 00:00:00 2001
From: Harper <harper.jme@gmail.com>
Date: Fri, 12 May 2023 13:01:44 +0100
Subject: [PATCH] fix: ignore duplicate consumed inputs (#257)

---
 pallas-traverse/src/input.rs | 30 ++++++++++++++++++++++++++++++
 pallas-traverse/src/lib.rs   |  2 +-
 pallas-traverse/src/tx.rs    | 25 ++++++++++++++++++++++---
 test_data/duplicateinput.tx  |  1 +
 4 files changed, 54 insertions(+), 4 deletions(-)
 create mode 100644 test_data/duplicateinput.tx

diff --git a/pallas-traverse/src/input.rs b/pallas-traverse/src/input.rs
index d7272e1..f3a9afb 100644
--- a/pallas-traverse/src/input.rs
+++ b/pallas-traverse/src/input.rs
@@ -138,6 +138,36 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_duplicate_consumed_inputs() {
+        let tx_bytecode_hex = include_str!("../../test_data/duplicateinput.tx");
+        let bytecode = hex::decode(tx_bytecode_hex).unwrap();
+        let tx = MultiEraTx::decode(Era::Alonzo, &bytecode).unwrap();
+
+        let expected_inputs = vec![
+            "4d9cb6bf1c2e349f1bcd454a632d2b721d5badcf687220430c316588f39506ab#1",
+            "4d9cb6bf1c2e349f1bcd454a632d2b721d5badcf687220430c316588f39506ab#1",
+        ];
+
+        let inputs: Vec<String> = tx
+            .inputs()
+            .into_iter()
+            .map(|x| x.output_ref().to_string())
+            .collect();
+
+        let expected_consumed =
+            vec!["4d9cb6bf1c2e349f1bcd454a632d2b721d5badcf687220430c316588f39506ab#1"];
+
+        let consumed: Vec<String> = tx
+            .consumes()
+            .into_iter()
+            .map(|x| x.output_ref().to_string())
+            .collect();
+
+        assert_eq!(inputs, expected_inputs);
+        assert_eq!(consumed, expected_consumed);
+    }
+
     #[test]
     fn test_utxo_ref_parsing() {
         let valid_vectors = [
diff --git a/pallas-traverse/src/lib.rs b/pallas-traverse/src/lib.rs
index 6d9191a..328b0bf 100644
--- a/pallas-traverse/src/lib.rs
+++ b/pallas-traverse/src/lib.rs
@@ -135,7 +135,7 @@ pub enum MultiEraSigners<'b> {
     AlonzoCompatible(&'b alonzo::RequiredSigners),
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct OutputRef(Hash<32>, u64);
 
 #[derive(Debug, Error)]
diff --git a/pallas-traverse/src/tx.rs b/pallas-traverse/src/tx.rs
index 3965c25..91374e6 100644
--- a/pallas-traverse/src/tx.rs
+++ b/pallas-traverse/src/tx.rs
@@ -1,4 +1,4 @@
-use std::{borrow::Cow, ops::Deref};
+use std::{borrow::Cow, collections::HashSet, ops::Deref};
 
 use pallas_codec::{minicbor, utils::KeepRaw};
 use pallas_crypto::hash::Hash;
@@ -114,6 +114,10 @@ impl<'b> MultiEraTx<'b> {
         }
     }
 
+    /// Return the transaction inputs
+    ///
+    /// NOTE: It is possible for this to return duplicates. See
+    /// https://github.com/input-output-hk/cardano-ledger/commit/a342b74f5db3d3a75eae3e2abe358a169701b1e7
     pub fn inputs(&self) -> Vec<MultiEraInput> {
         match self {
             MultiEraTx::AlonzoCompatible(x, _) => x
@@ -137,6 +141,10 @@ impl<'b> MultiEraTx<'b> {
         }
     }
 
+    /// Return the transaction reference inputs
+    ///
+    /// NOTE: It is possible for this to return duplicates. See
+    /// https://github.com/input-output-hk/cardano-ledger/commit/a342b74f5db3d3a75eae3e2abe358a169701b1e7
     pub fn reference_inputs(&self) -> Vec<MultiEraInput> {
         match self {
             MultiEraTx::Babbage(x) => x
@@ -192,6 +200,10 @@ impl<'b> MultiEraTx<'b> {
         }
     }
 
+    /// Return the transaction collateral inputs
+    ///
+    /// NOTE: It is possible for this to return duplicates. See
+    /// https://github.com/input-output-hk/cardano-ledger/commit/a342b74f5db3d3a75eae3e2abe358a169701b1e7
     pub fn collateral(&self) -> Vec<MultiEraInput> {
         match self {
             MultiEraTx::AlonzoCompatible(x, _) => x
@@ -230,10 +242,17 @@ impl<'b> MultiEraTx<'b> {
     /// will return the list of inputs. If the tx is invalid, it will return the
     /// collateral.
     pub fn consumes(&self) -> Vec<MultiEraInput> {
-        match self.is_valid() {
+        let consumed = match self.is_valid() {
             true => self.inputs(),
             false => self.collateral(),
-        }
+        };
+
+        let mut unique_consumed = HashSet::new();
+
+        consumed
+            .into_iter()
+            .filter(|i| unique_consumed.insert(i.output_ref()))
+            .collect()
     }
 
     /// Returns a list of tuples of the outputs produced by the Tx with their
diff --git a/test_data/duplicateinput.tx b/test_data/duplicateinput.tx
new file mode 100644
index 0000000..6b8cecc
--- /dev/null
+++ b/test_data/duplicateinput.tx
@@ -0,0 +1 @@
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
\ No newline at end of file