From 7c1d4d9a5b63330d71884dc78fefcefaf8b384d5 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Sun, 18 Aug 2019 23:56:15 +0100
Subject: [PATCH] Log distinct error cases in Equihash verification

---
 Cargo.lock                             | 10 ++++++++++
 zcash_primitives/Cargo.toml            |  1 +
 zcash_primitives/src/block/equihash.rs |  7 ++++---
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index d6f658a..623bcc0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -317,6 +317,14 @@ dependencies = [
  "zcash_proofs 0.0.0",
 ]
 
+[[package]]
+name = "log"
+version = "0.4.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "nodrop"
 version = "0.1.13"
@@ -535,6 +543,7 @@ dependencies = [
  "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "hex-literal 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "pairing 0.14.2",
  "rand 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -594,6 +603,7 @@ dependencies = [
 "checksum hex-literal-impl 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "520870c3213943eb8d7803e80180d12a6c7ceb4ae74602544529d1643dc4ddda"
 "checksum lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bc5729f27f159ddd61f4df6228e827e86643d4d3e7c32183cb30a1c08f604a14"
 "checksum libc 0.2.61 (registry+https://github.com/rust-lang/crates.io-index)" = "c665266eb592905e8503ba3403020f4b8794d26263f412ca33171600eca9a6fa"
+"checksum log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)" = "14b6052be84e6b71ab17edffc2eeabf5c2c3ae1fdb464aae35ac50c67a44e1f7"
 "checksum nodrop 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "2f9667ddcc6cc8a43afc9b7917599d7216aa09c463919ea32c59ed6cac8bc945"
 "checksum num-bigint 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "57450397855d951f1a41305e54851b1a7b8f5d2e349543a02a2effe25459f718"
 "checksum num-integer 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)" = "b85e541ef8255f6cf42bbfe4ef361305c6c135d10919ecc26126c4e5ae94bc09"
diff --git a/zcash_primitives/Cargo.toml b/zcash_primitives/Cargo.toml
index 5e1bf91..7019dec 100644
--- a/zcash_primitives/Cargo.toml
+++ b/zcash_primitives/Cargo.toml
@@ -16,6 +16,7 @@ ff = { path = "../ff" }
 fpe = "0.2"
 hex = "0.3"
 lazy_static = "1"
+log = "0.4"
 pairing = { path = "../pairing" }
 rand = "0.7"
 rand_core = "0.5"
diff --git a/zcash_primitives/src/block/equihash.rs b/zcash_primitives/src/block/equihash.rs
index 9710dc9..2a3bb66 100644
--- a/zcash_primitives/src/block/equihash.rs
+++ b/zcash_primitives/src/block/equihash.rs
@@ -1,5 +1,6 @@
 use blake2b_simd::{Hash as Blake2bHash, Params as Blake2bParams, State as Blake2bState};
 use byteorder::{BigEndian, LittleEndian, ReadBytesExt, WriteBytesExt};
+use log::error;
 use std::io::Cursor;
 use std::mem::size_of;
 
@@ -196,13 +197,13 @@ fn distinct_indices(a: &Node, b: &Node) -> bool {
 
 fn validate_subtrees(p: &Params, a: &Node, b: &Node) -> bool {
     if !has_collision(a, b, p.collision_byte_length()) {
-        // error!("Invalid solution: invalid collision length between StepRows");
+        error!("Invalid solution: invalid collision length between StepRows");
         false
     } else if b.indices_before(a) {
-        // error!("Invalid solution: Index tree incorrectly ordered");
+        error!("Invalid solution: Index tree incorrectly ordered");
         false
     } else if !distinct_indices(a, b) {
-        // error!("Invalid solution: duplicate indices");
+        error!("Invalid solution: duplicate indices");
         false
     } else {
         true