From f2b467c8d7d761dd47e58ad9ed4d8ede92a24601 Mon Sep 17 00:00:00 2001
From: CryptoManiac <balthazar@yandex.ru>
Date: Sat, 12 Mar 2016 23:13:03 +0300
Subject: [PATCH] List of unconditionally banned blocks.

Unlike with checkpoints, block height doesn't matter here.
---
 src/checkpoints.cpp |   16 ++++++++++++++++
 src/checkpoints.h   |    3 +++
 src/main.cpp        |    7 +++++++
 3 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/src/checkpoints.cpp b/src/checkpoints.cpp
index dba4b21..095def3 100644
--- a/src/checkpoints.cpp
+++ b/src/checkpoints.cpp
@@ -4,6 +4,7 @@
 
 #include <boost/assign/list_of.hpp> // for 'map_list_of()'
 #include <boost/foreach.hpp>
+#include <algorithm>
 
 #include "checkpoints.h"
 
@@ -14,6 +15,7 @@
 namespace Checkpoints
 {
     typedef std::map<int, std::pair<uint256, unsigned int> > MapCheckpoints;
+    typedef std::list<uint256> ListBannedBlocks;
 
     //
     // What makes a good checkpoint block?
@@ -32,6 +34,12 @@ namespace Checkpoints
         ( 200000, std::make_pair(uint256("0x0000000000029f8bbf66e6ea6f3e5db55009404aae0fe395a53dd33142b2bff2"), 1441127233) )
         ( 221047, std::make_pair(uint256("0xa28aef712e7aa0c285bfe29351ca21ed416689139e3063ef770fc826a8b9e9da"), 1449431646) )
     ;
+    
+    static ListBannedBlocks listBanned =
+        boost::assign::list_of
+        // Invalid block #221047 with future timestamp of 2016/02/23 09:24:17 UTC
+        ( uint256("0x46223e5432ceffe650d5729b4bb8479dcdf0ca1e534fa8e69382dc87b42ea94b") )
+    ;
 
     // TestNet has no checkpoints
     static MapCheckpoints mapCheckpointsTestnet =
@@ -48,6 +56,14 @@ namespace Checkpoints
         return hash == i->second.first;
     }
 
+    bool CheckBanned(const uint256 &nHash)
+    {
+        if (fTestNet) // Testnet has no banned blocks
+            return true;
+        ListBannedBlocks::const_iterator it = std::find(listBanned.begin(), listBanned.end(), nHash);
+        return it == listBanned.end();
+    }
+
     int GetTotalBlocksEstimate()
     {
         MapCheckpoints& checkpoints = (fTestNet ? mapCheckpointsTestnet : mapCheckpoints);
diff --git a/src/checkpoints.h b/src/checkpoints.h
index 347b2d0..0250618 100644
--- a/src/checkpoints.h
+++ b/src/checkpoints.h
@@ -40,6 +40,9 @@ namespace Checkpoints
     // Returns true if block passes checkpoint checks
     bool CheckHardened(int nHeight, const uint256& hash);
 
+    // Returns true if block passes banlist checks
+    bool CheckBanned(const uint256 &nHash);
+
     // Return conservative estimate of total number of blocks, 0 if unknown
     int GetTotalBlocksEstimate();
 
diff --git a/src/main.cpp b/src/main.cpp
index bdc7e8d..1a90e51 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2528,6 +2528,13 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
     if (mapOrphanBlocks.count(hash))
         return error("ProcessBlock() : already have block (orphan) %s", hash.ToString().substr(0,20).c_str());
 
+    // Check that block isn't listed as unconditionally banned.
+    if (!Checkpoints::CheckBanned(hash)) {
+        if (pfrom)
+            pfrom->Misbehaving(100);
+        return error("ProcessBlock() : block %s is rejected by hard-coded banlist", hash.GetHex().substr(0,20).c_str());
+    }
+
     // Check proof-of-stake
     // Limited duplicity on stake: prevents block flood attack
     // Duplicate stake allowed only when there is orphan child block
-- 
1.7.1