From cfdf0d2f0a94ebf7d3f6968627df4bbfdd73fee0 Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Mon, 27 Jul 2015 14:38:06 -0700
Subject: [PATCH] Remove a ledger from the set of present ledgers where needed
 * If we encounter it in RPC * If we fully-validate a ledger that doesn't have
 it in its history

---
 src/ripple/app/ledger/impl/LedgerMaster.cpp |  9 +++++++++
 src/ripple/rpc/impl/LookupLedger.cpp        | 13 +++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/ripple/app/ledger/impl/LedgerMaster.cpp b/src/ripple/app/ledger/impl/LedgerMaster.cpp
index 1934225d1..97c1fb11f 100644
--- a/src/ripple/app/ledger/impl/LedgerMaster.cpp
+++ b/src/ripple/app/ledger/impl/LedgerMaster.cpp
@@ -695,6 +695,15 @@ public:
         if (isCurrent)
             mLedgerHistory.addLedger(ledger, true);
 
+        {
+            // Check the SQL database's entry for the sequence before this ledger,
+            // if it's not this ledger's parent, invalidate it
+            uint256 prevHash = Ledger::getHashByIndex (ledger->info().seq - 1);
+            if (prevHash.isNonZero () && (prevHash != ledger->info().parentHash))
+                clearLedger (ledger->info().seq - 1);
+        }
+
+
         ledger->pendSaveValidated (isSynchronous, isCurrent);
 
         {
diff --git a/src/ripple/rpc/impl/LookupLedger.cpp b/src/ripple/rpc/impl/LookupLedger.cpp
index 4a036d6ac..68330ddb6 100644
--- a/src/ripple/rpc/impl/LookupLedger.cpp
+++ b/src/ripple/rpc/impl/LookupLedger.cpp
@@ -152,8 +152,21 @@ bool isValidated (LedgerMaster& ledgerMaster, ReadView const& ledger)
         // comes before the last validated ledger (and thus has been
         // validated).
         auto hash = ledgerMaster.walkHashBySeq (seq);
+
         if (ledger.info().hash != hash)
+        {
+            // This ledger's hash is not the hash of the validated ledger
+            if (hash.isNonZero ())
+            {
+                uint256 valHash = Ledger::getHashByIndex (seq);
+                if (valHash == ledger.info().hash)
+                {
+                    // SQL database doesn't match ledger chain
+                    ledgerMaster.clearLedger (seq);
+                }
+            }
             return false;
+        }
     }
     catch (SHAMapMissingNode const&)
     {