1 files changed, 55 insertions, 15 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 7dd59fdea..71d425e15 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -281,9 +281,12 @@ bool CTransaction::IsStandard() const
         if (!txin.scriptSig.IsPushOnly())
             return false;
     }
-    BOOST_FOREACH(const CTxOut& txout, vout)
+    BOOST_FOREACH(const CTxOut& txout, vout) {
         if (!::IsStandard(txout.scriptPubKey))
             return false;
+        if (txout.nValue == 0)
+            return false;
+    }
     return true;
 }
 
@@ -653,8 +656,7 @@ bool CTxMemPool::remove(CTransaction &tx)
     return true;
 }
 
-void
-CTxMemPool::clear()
+void CTxMemPool::clear()
 {
     LOCK(cs);
     mapTx.clear();
@@ -1920,17 +1922,20 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
     }
 
 
-    // If don't already have its previous block, shunt it off to holding area until we get it
+    // If we don't already have its previous block, shunt it off to holding area until we get it
     if (!mapBlockIndex.count(pblock->hashPrevBlock))
     {
         printf("ProcessBlock: ORPHAN BLOCK, prev=%s\n", pblock->hashPrevBlock.ToString().substr(0,20).c_str());
-        CBlock* pblock2 = new CBlock(*pblock);
-        mapOrphanBlocks.insert(make_pair(hash, pblock2));
-        mapOrphanBlocksByPrev.insert(make_pair(pblock2->hashPrevBlock, pblock2));
 
-        // Ask this guy to fill in what we're missing
-        if (pfrom)
+        // Accept orphans as long as there is a node to request its parents from
+        if (pfrom) {
+            CBlock* pblock2 = new CBlock(*pblock);
+            mapOrphanBlocks.insert(make_pair(hash, pblock2));
+            mapOrphanBlocksByPrev.insert(make_pair(pblock2->hashPrevBlock, pblock2));
+
+            // Ask this guy to fill in what we're missing
             pfrom->PushGetBlocks(pindexBest, GetOrphanRoot(pblock2));
+        }
         return true;
     }
 
@@ -2317,6 +2322,28 @@ bool CAlert::ProcessAlert()
     if (!IsInEffect())
         return false;
 
+    // alert.nID=max is reserved for if the alert key is
+    // compromised. It must have a pre-defined message,
+    // must never expire, must apply to all versions,
+    // and must cancel all previous
+    // alerts or it will be ignored (so an attacker can't
+    // send an "everything is OK, don't panic" version that
+    // cannot be overridden):
+    int maxInt = std::numeric_limits<int>::max();
+    if (nID == maxInt)
+    {
+        if (!(
+                nExpiration == maxInt &&
+                nCancel == (maxInt-1) &&
+                nMinVer == 0 &&
+                nMaxVer == maxInt &&
+                setSubVer.empty() &&
+                nPriority == maxInt &&
+                strStatusBar == "URGENT: Alert key compromised, upgrade required"
+                ))
+            return false;
+    }
+
     {
         LOCK(cs_mapAlerts);
         // Cancel previous alerts
@@ -2992,14 +3019,27 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         CAlert alert;
         vRecv >> alert;
 
-        if (alert.ProcessAlert())
+        uint256 alertHash = alert.GetHash();
+        if (pfrom->setKnown.count(alertHash) == 0)
         {
-            // Relay
-            pfrom->setKnown.insert(alert.GetHash());
+            if (alert.ProcessAlert())
             {
-                LOCK(cs_vNodes);
-                BOOST_FOREACH(CNode* pnode, vNodes)
-                    alert.RelayTo(pnode);
+                // Relay
+                pfrom->setKnown.insert(alertHash);
+                {
+                    LOCK(cs_vNodes);
+                    BOOST_FOREACH(CNode* pnode, vNodes)
+                        alert.RelayTo(pnode);
+                }
+            }
+            else {
+                // Small DoS penalty so peers that send us lots of
+                // duplicate/expired/invalid-signature/whatever alerts
+                // eventually get banned.
+                // This isn't a Misbehaving(100) (immediate ban) because the
+                // peer might be an older or different implementation with
+                // a different signature key, etc.
+                pfrom->Misbehaving(10);
             }
         }
     }