PPCoin: Synchronized checkpoint accepting descendant blocks only

[novacoin.git] / src / checkpoints.cpp

diff --git a/src/checkpoints.cpp b/src/checkpoints.cpp
index 4afdab9..888d106 100644 (file)
--- a/src/checkpoints.cpp
+++ b/src/checkpoints.cpp
@@ -77,25 +77,29 @@ namespace Checkpoints
 
         CBlockIndex* pindex = pindexCheckpointRecv;
         while (pindex->nHeight > pindexSyncCheckpoint->nHeight)
-            pindex = pindex->pprev;
+            if (!(pindex = pindex->pprev))
+                return error("ValidateSyncCheckpoint: pprev null - block index structure failure");
         if (pindex->GetBlockHash() != hashSyncCheckpoint)
             return error("ValidateSyncCheckpoint: new sync-checkpoint %s is not a descendant of current sync-checkpoint %s", hashCheckpoint.ToString().c_str(), hashSyncCheckpoint.ToString().c_str());
         return true;
     }
 
-    bool AcceptPendingSyncCheckpoint(uint256 hashAcceptedBlock)
+    bool AcceptPendingSyncCheckpoint()
     {
-        if (!mapBlockIndex.count(hashAcceptedBlock))
-            return false;
-
         CRITICAL_BLOCK(cs_hashSyncCheckpoint)
-            if ((!checkpointMessagePending.IsNull()) && checkpointMessagePending.hashCheckpoint == hashAcceptedBlock)
+            if ((!checkpointMessagePending.IsNull()) && mapBlockIndex.count(checkpointMessagePending.hashCheckpoint))
             {
                 if (!ValidateSyncCheckpoint(checkpointMessagePending.hashCheckpoint))
                 {
                     checkpointMessagePending.SetNull();
                     return false;
                 }
+
+                CTxDB txdb;
+                if (!txdb.WriteSyncCheckpoint(checkpointMessagePending.hashCheckpoint))
+                    return error("AcceptPendingSyncCheckpoint() : failed to write to db sync checkpoint %s\n", checkpointMessagePending.hashCheckpoint.ToString().c_str());
+                txdb.Close();
+
                 hashSyncCheckpoint = checkpointMessagePending.hashCheckpoint;
                 checkpointMessage = checkpointMessagePending;
                 checkpointMessagePending.SetNull();
@@ -109,6 +113,45 @@ namespace Checkpoints
         return false;
     }
 
+    uint256 AutoSelectSyncCheckpoint()
+    {
+        // select block roughly 8 hours ago
+        CBlockIndex *pindex = mapBlockIndex[hashSyncCheckpoint];
+        while (pindex->pnext && pindex->pnext->GetBlockTime() + AUTO_CHECKPOINT_MIN_SPAN <= GetAdjustedTime())
+            pindex = pindex->pnext;
+        return pindex->GetBlockHash();
+    }
+
+    // Check against synchronized checkpoint
+    bool CheckSync(const uint256& hashBlock, const CBlockIndex* pindexPrev)
+    {
+        if (fTestNet) return true; // Testnet has no checkpoints
+        int nHeight = pindexPrev->nHeight + 1;
+
+        CRITICAL_BLOCK(cs_hashSyncCheckpoint)
+        {
+            // sync-checkpoint should always be accepted block
+            assert(mapBlockIndex.count(hashSyncCheckpoint));
+            const CBlockIndex* pindexSync = mapBlockIndex[hashSyncCheckpoint];
+
+            if (nHeight > pindexSync->nHeight)
+            {
+                // trace back to same height as sync-checkpoint
+                const CBlockIndex* pindex = pindexPrev;
+                while (pindex->nHeight > pindexSync->nHeight)
+                    if (!(pindex = pindex->pprev))
+                        return error("CheckSync: pprev null - block index structure failure");
+                if (pindex->nHeight < pindexSync->nHeight || pindex->GetBlockHash() != hashSyncCheckpoint)
+                    return false; // only descendant of sync-checkpoint can pass check
+            }
+            if (nHeight == pindexSync->nHeight && hashBlock != hashSyncCheckpoint)
+                return false; // same height with sync-checkpoint
+            if (nHeight < pindexSync->nHeight && !mapBlockIndex.count(hashBlock))
+                return false; // lower height than sync-checkpoint
+        }
+        return true;
+    }
+
     // ppcoin: automatic checkpoint (represented by height of checkpoint)
     int nAutoCheckpoint = 0;
     int nBranchPoint = 0;    // branch point to alternative branch
@@ -247,6 +290,12 @@ bool CSyncCheckpoint::ProcessSyncCheckpoint(CNode* pfrom)
         }
         if (!Checkpoints::ValidateSyncCheckpoint(hashCheckpoint))
             return false;
+
+        CTxDB txdb;
+        if (!txdb.WriteSyncCheckpoint(this->hashCheckpoint))
+            return error("ProcessSyncCheckpoint() : failed to write to db sync checkpoint %s\n", this->hashCheckpoint.ToString().c_str());
+        txdb.Close();
+
         Checkpoints::hashSyncCheckpoint = this->hashCheckpoint;
         Checkpoints::checkpointMessage = *this;
         Checkpoints::checkpointMessagePending.SetNull();