From 005a29c1d5e38f9bfb92081c5aae24bc7ac7b17f Mon Sep 17 00:00:00 2001
From: unknownunknown1 <time_arrow@bk.ru>
Date: Mon, 29 Aug 2022 00:23:02 +1000
Subject: [PATCH 1/2] fix(RNG): add lookahead of 132 blocks

---
 contracts/standard/rng/BeaconRNGFallback.sol | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/contracts/standard/rng/BeaconRNGFallback.sol b/contracts/standard/rng/BeaconRNGFallback.sol
index bdc130b9..35fd7a24 100644
--- a/contracts/standard/rng/BeaconRNGFallback.sol
+++ b/contracts/standard/rng/BeaconRNGFallback.sol
@@ -1,6 +1,6 @@
  /**
- *  @authors: [@shalzz]
- *  @reviewers: [@jaybuidl*, @geaxed]
+ *  @authors: [@shalzz, @unknownunknown1]
+ *  @reviewers: [@jaybuidl*, @geaxed*]
  *  @auditors: []
  *  @bounties: []
  *  @deployments: []
@@ -18,6 +18,8 @@ contract BeaconRNGFallBack is RNG {
     RNG public beaconRNG;
     RNG public blockhashRNG;
 
+    uint public constant LOOKAHEAD = 132; // Number of blocks that has to pass before obtaining the random number. 4 epochs + 4 slots, according to EIP-4399.
+
     /** @dev Constructor.
      * @param _beaconRNG The beacon chain RNG deployed contract address
      * @param _blockhashRNG The blockhash RNG deployed contract address
@@ -65,6 +67,10 @@ contract BeaconRNGFallBack is RNG {
         // fallback to blockhash RNG
         if (RN == 0) {
             RN = blockhashRNG.getRN(_block);
+        } else if (block.number < _block + LOOKAHEAD) {
+            // Beacon chain returns the random number, but sufficient number of blocks hasn't been mined yet.
+            // In this case signal to the court that RN isn't ready.
+            RN = 0;
         }
     }
 }

From b845c79a66b454ff71521c90c5baa9f6f7e5004e Mon Sep 17 00:00:00 2001
From: jaybuidl <jb@kleros.io>
Date: Mon, 29 Aug 2022 11:46:51 +0100
Subject: [PATCH 2/2] docs: rab update

---
 contracts/standard/rng/BeaconRNGFallback.sol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contracts/standard/rng/BeaconRNGFallback.sol b/contracts/standard/rng/BeaconRNGFallback.sol
index 35fd7a24..54c5f9df 100644
--- a/contracts/standard/rng/BeaconRNGFallback.sol
+++ b/contracts/standard/rng/BeaconRNGFallback.sol
@@ -1,6 +1,6 @@
  /**
  *  @authors: [@shalzz, @unknownunknown1]
- *  @reviewers: [@jaybuidl*, @geaxed*]
+ *  @reviewers: [@jaybuidl, @geaxed*]
  *  @auditors: []
  *  @bounties: []
  *  @deployments: []