Fix some locks

This makes sure that cs_filter is never held while taking cs_main
or CNode::cs_vSend.

Author: sipa

src/main.cpp

@@ -4781,10 +4781,16 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
                         pfrom->PushMessage(NetMsgType::BLOCK, block);
                     else if (inv.type == MSG_FILTERED_BLOCK)
                     {
-                        LOCK(pfrom->cs_filter);
-                        if (pfrom->pfilter)
+                        bool send = false;
+                        CMerkleBlock merkleBlock;
                         {
-                            CMerkleBlock merkleBlock(block, *pfrom->pfilter);
+                            LOCK(pfrom->cs_filter);
+                            if (pfrom->pfilter) {
+                                send = true;
+                                merkleBlock = CMerkleBlock(block, *pfrom->pfilter);
+                            }
+                        }
+                        if (send) {
                             pfrom->PushMessage(NetMsgType::MERKLEBLOCK, merkleBlock);
                             // CMerkleBlock just contains hashes, so also push any transactions in the block the client did not see
                             // This avoids hurting performance by pointlessly requiring a round-trip
@@ -6052,8 +6058,6 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         CBloomFilter filter;
         vRecv >> filter;
 
-        LOCK(pfrom->cs_filter);
-
         if (!filter.IsWithinSizeConstraints())
         {
             // There is no excuse for sending a too-large filter
@@ -6062,11 +6066,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         }
         else
         {
+            LOCK(pfrom->cs_filter);
             delete pfrom->pfilter;
             pfrom->pfilter = new CBloomFilter(filter);
             pfrom->pfilter->UpdateEmptyFull();
+            pfrom->fRelayTxes = true;
         }
-        pfrom->fRelayTxes = true;
     }
 
 
@@ -6077,20 +6082,21 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
 
         // Nodes must NEVER send a data item > 520 bytes (the max size for a script data object,
         // and thus, the maximum size any matched object can have) in a filteradd message
-        if (vData.size() > MAX_SCRIPT_ELEMENT_SIZE)
-        {
-            LOCK(cs_main);
-            Misbehaving(pfrom->GetId(), 100);
+        bool bad = false;
+        if (vData.size() > MAX_SCRIPT_ELEMENT_SIZE) {
+            bad = true;
         } else {
             LOCK(pfrom->cs_filter);
-            if (pfrom->pfilter)
+            if (pfrom->pfilter) {
                 pfrom->pfilter->insert(vData);
-            else
-            {
-                LOCK(cs_main);
-                Misbehaving(pfrom->GetId(), 100);
+            } else {
+                bad = true;
             }
         }
+        if (bad) {
+            LOCK(cs_main);
+            Misbehaving(pfrom->GetId(), 100);
+        }
     }