Backport Bitcoin PR#9075: Decouple peer-processing-logic from block-c…

…onnection-logic (#3) (#1560)

* Remove pfrom parameter from ProcessNewBlock

This further decouples ProcessNewBlock from networking/peer logic.

* Replace CValidationState param in ProcessNewBlock with BlockChecked

src/main.cpp

@@ -3971,26 +3971,26 @@ static bool IsSuperMajority(int minVersion, const CBlockIndex* pstart, unsigned
 }
 
 
-bool ProcessNewBlock(CValidationState& state, const CChainParams& chainparams, CNode* pfrom, const CBlock* pblock, bool fForceProcessing, const CDiskBlockPos* dbp)
+bool ProcessNewBlock(const CChainParams& chainparams, const CBlock* pblock, bool fForceProcessing, const CDiskBlockPos* dbp, bool *fNewBlock)
 {
     {
         LOCK(cs_main);
 
         // Store to disk
         CBlockIndex *pindex = NULL;
-        bool fNewBlock = false;
-        bool ret = AcceptBlock(*pblock, state, chainparams, &pindex, fForceProcessing, dbp, &fNewBlock);
-        if (pindex && pfrom) {
-            mapBlockSource[pindex->GetBlockHash()] = pfrom->GetId();
-            if (fNewBlock) pfrom->nLastBlockTime = GetTime();
-        }
+        if (fNewBlock) *fNewBlock = false;
+        CValidationState state;
+        bool ret = AcceptBlock(*pblock, state, chainparams, &pindex, fForceProcessing, dbp, fNewBlock);
         CheckBlockIndex(chainparams.GetConsensus());
-        if (!ret)
+        if (!ret) {
+            GetMainSignals().BlockChecked(*pblock, state);
             return error("%s: AcceptBlock FAILED", __func__);
+        }
     }
 
     NotifyHeaderTip();
 
+    CValidationState state; // Only used to report errors, not invalidity - ignore it
     if (!ActivateBestChain(state, chainparams, pblock))
         return error("%s: ActivateBestChain failed", __func__);
 
@@ -6118,30 +6118,25 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
 
         pfrom->AddInventoryKnown(inv);
 
-        CValidationState state;
         // Process all blocks from whitelisted peers, even if not requested,
         // unless we're still syncing with the network.
         // Such an unrequested block may still be processed, subject to the
         // conditions in AcceptBlock().
         bool forceProcessing = pfrom->fWhitelisted && !IsInitialBlockDownload();
+        const uint256 hash(block.GetHash());
         {
             LOCK(cs_main);
             // Also always process if we requested the block explicitly, as we may
             // need it even though it is not a candidate for a new best tip.
-            forceProcessing |= MarkBlockAsReceived(block.GetHash());
-        }
-        ProcessNewBlock(state, chainparams, pfrom, &block, forceProcessing, NULL);
-        int nDoS;
-        if (state.IsInvalid(nDoS)) {
-            assert (state.GetRejectCode() < REJECT_INTERNAL); // Blocks are never rejected with internal reject codes
-            connman.PushMessage(pfrom, NetMsgType::REJECT, strCommand, (unsigned char)state.GetRejectCode(),
-                               state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), inv.hash);
-            if (nDoS > 0) {
-                LOCK(cs_main);
-                Misbehaving(pfrom->GetId(), nDoS);
-            }
+            forceProcessing |= MarkBlockAsReceived(hash);
+            // mapBlockSource is only used for sending reject messages and DoS scores,
+            // so the race between here and cs_main in ProcessNewBlock is fine.
+            mapBlockSource.emplace(hash, pfrom->GetId());
         }
-
+        bool fNewBlock = false;
+        ProcessNewBlock(chainparams, &block, forceProcessing, NULL, &fNewBlock);
+        if (fNewBlock)
+            pfrom->nLastBlockTime = GetTime();
     }
 
 

src/main.h

@@ -193,15 +193,21 @@ static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
  * Process an incoming block. This only returns after the best known valid
  * block is made active. Note that it does not, however, guarantee that the
  * specific block passed to it has been checked for validity!
+ *
+ * If you want to *possibly* get feedback on whether pblock is valid, you must
+ * install a CValidationInterface (see validationinterface.h) - this will have
+ * its BlockChecked method called whenever *any* block completes validation.
+ *
+ * Note that we guarantee that either the proof-of-work is valid on pblock, or
+ * (and possibly also) BlockChecked will have been called.
  * 
- * @param[out]  state   This may be set to an Error state if any error occurred processing it, including during validation/connection/etc of otherwise unrelated blocks during reorganisation; or it may be set to an Invalid state if pblock is itself invalid (but this is not guaranteed even when the block is checked). If you want to *possibly* get feedback on whether pblock is valid, you must also install a CValidationInterface (see validationinterface.h) - this will have its BlockChecked method called whenever *any* block completes validation.
- * @param[in]   pfrom   The node which we are receiving the block from; it is added to mapBlockSource and may be penalised if the block is invalid.
  * @param[in]   pblock  The block we want to process.
  * @param[in]   fForceProcessing Process this block even if unrequested; used for non-network block sources and whitelisted peers.
  * @param[out]  dbp     The already known disk position of pblock, or NULL if not yet stored.
+ * @param[out]  fNewBlock A boolean which is set to indicate if the block was first received via this call
  * @return True if state.IsValid()
  */
-bool ProcessNewBlock(CValidationState& state, const CChainParams& chainparams, CNode* pfrom, const CBlock* pblock, bool fForceProcessing, const CDiskBlockPos* dbp);
+bool ProcessNewBlock(const CChainParams& chainparams, const CBlock* pblock, bool fForceProcessing, const CDiskBlockPos* dbp, bool* fNewBlock);
 /** Check whether enough disk space is available for an incoming block */
 bool CheckDiskSpace(uint64_t nAdditionalBytes = 0);
 /** Open a block file (blk?????.dat) */

src/miner.cpp

@@ -392,8 +392,7 @@ static bool ProcessBlockFound(const CBlock* pblock, const CChainParams& chainpar
     GetMainSignals().BlockFound(pblock->GetHash());
 
     // Process this block the same as if we had received it from another node
-    CValidationState state;
-    if (!ProcessNewBlock(state, chainparams, NULL, pblock, true, NULL))
+    if (!ProcessNewBlock(chainparams, pblock, true, NULL, NULL))
         return error("ProcessBlockFound -- ProcessNewBlock() failed, block not accepted");
 
     return true;

src/rpc/mining.cpp

@@ -177,8 +177,7 @@ UniValue generate(const UniValue& params, bool fHelp)
             // target -- 1 in 2^(2^32). That ain't gonna happen.
             ++pblock->nNonce;
         }
-        CValidationState state;
-        if (!ProcessNewBlock(state, Params(), NULL, pblock, true, NULL))
+        if (!ProcessNewBlock(Params(), pblock, true, NULL, NULL))
             throw JSONRPCError(RPC_INTERNAL_ERROR, "ProcessNewBlock, block not accepted");
         ++nHeight;
         blockHashes.push_back(pblock->GetHash().GetHex());
@@ -794,24 +793,19 @@ UniValue submitblock(const UniValue& params, bool fHelp)
         }
     }
 
-    CValidationState state;
     submitblock_StateCatcher sc(block.GetHash());
     RegisterValidationInterface(&sc);
-    bool fAccepted = ProcessNewBlock(state, Params(), NULL, &block, true, NULL);
+    bool fAccepted = ProcessNewBlock(Params(), &block, true, NULL, NULL);
     UnregisterValidationInterface(&sc);
     if (fBlockPresent)
     {
         if (fAccepted && !sc.found)
             return "duplicate-inconclusive";
         return "duplicate";
     }
-    if (fAccepted)
-    {
-        if (!sc.found)
-            return "inconclusive";
-        state = sc.state;
-    }
-    return BIP22ValidationResult(state);
+    if (!sc.found)
+        return "inconclusive";
+    return BIP22ValidationResult(sc.state);
 }
 
 UniValue estimatefee(const UniValue& params, bool fHelp)

src/test/miner_tests.cpp

@@ -117,9 +117,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
             txFirst.push_back(new CTransaction(pblock->vtx[0]));
         pblock->hashMerkleRoot = BlockMerkleRoot(*pblock);
         pblock->nNonce = blockinfo[i].nonce;
-        CValidationState state;
-        BOOST_CHECK(ProcessNewBlock(state, chainparams, NULL, pblock, true, NULL));
-        BOOST_CHECK(state.IsValid());
+        BOOST_CHECK(ProcessNewBlock(chainparams, pblock, true, NULL, NULL));
         pblock->hashPrevBlock = pblock->GetHash();
     }
     delete pblocktemplate;

src/test/test_dash.cpp

@@ -135,8 +135,7 @@ TestChain100Setup::CreateAndProcessBlock(const std::vector<CMutableTransaction>&
 
     while (!CheckProofOfWork(block.GetHash(), block.nBits, chainparams.GetConsensus())) ++block.nNonce;
 
-    CValidationState state;
-    ProcessNewBlock(state, chainparams, NULL, &block, true, NULL);
+    ProcessNewBlock(chainparams, &block, true, NULL, NULL);
 
     CBlock result = block;
     delete pblocktemplate;