Merge pull request #5875

aa8c827 P2P regression test for new AcceptBlock behavior (Suhas Daftuar)
9be0e68 Be stricter in processing unrequested blocks (Suhas Daftuar)

qa/pull-tester/rpc-tests.sh

@@ -51,6 +51,7 @@ testScriptsExt=(
     'invalidblockrequest.py'
     'rawtransactions.py'
 #    'forknotify.py'
+    'p2p-acceptblock.py'
 );
 
 extArg="-extended"

qa/rpc-tests/p2p-acceptblock.py

@@ -0,0 +1,226 @@
+#!/usr/bin/env python2
+#
+# Distributed under the MIT/X11 software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+
+from test_framework.mininode import *
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import *
+import time
+from test_framework.blocktools import create_block, create_coinbase
+
+'''
+AcceptBlockTest -- test processing of unrequested blocks.
+
+Since behavior differs when receiving unrequested blocks from whitelisted peers
+versus non-whitelisted peers, this tests the behavior of both (effectively two
+separate tests running in parallel).
+
+Setup: two nodes, node0 and node1, not connected to each other.  Node0 does not
+whitelist localhost, but node1 does. They will each be on their own chain for
+this test.
+
+We have one NodeConn connection to each, test_node and white_node respectively.
+
+The test:
+1. Generate one block on each node, to leave IBD.
+
+2. Mine a new block on each tip, and deliver to each node from node's peer.
+   The tip should advance.
+
+3. Mine a block that forks the previous block, and deliver to each node from
+   corresponding peer.
+   Node0 should not process this block (just accept the header), because it is
+   unrequested and doesn't have more work than the tip.
+   Node1 should process because this is coming from a whitelisted peer.
+
+4. Send another block that builds on the forking block.
+   Node0 should process this block but be stuck on the shorter chain, because
+   it's missing an intermediate block.
+   Node1 should reorg to this longer chain.
+
+5. Send a duplicate of the block in #3 to Node0.
+   Node0 should not process the block because it is unrequested, and stay on
+   the shorter chain.
+
+6. Send Node0 an inv for the height 3 block produced in #4 above.
+   Node0 should figure out that Node0 has the missing height 2 block and send a
+   getdata.
+
+7. Send Node0 the missing block again.
+   Node0 should process and the tip should advance.
+'''
+
+# TestNode: bare-bones "peer".  Used mostly as a conduit for a test to sending
+# p2p messages to a node, generating the messages in the main testing logic.
+class TestNode(NodeConnCB):
+    def __init__(self):
+        NodeConnCB.__init__(self)
+        self.create_callback_map()
+        self.connection = None
+
+    def add_connection(self, conn):
+        self.connection = conn
+
+    # Track the last getdata message we receive (used in the test)
+    def on_getdata(self, conn, message):
+        self.last_getdata = message
+
+    # Spin until verack message is received from the node.
+    # We use this to signal that our test can begin. This
+    # is called from the testing thread, so it needs to acquire
+    # the global lock.
+    def wait_for_verack(self):
+        while True:
+            with mininode_lock:
+                if self.verack_received:
+                    return
+            time.sleep(0.05)
+
+    # Wrapper for the NodeConn's send_message function
+    def send_message(self, message):
+        self.connection.send_message(message)
+
+class AcceptBlockTest(BitcoinTestFramework):
+    def add_options(self, parser):
+        parser.add_option("--testbinary", dest="testbinary",
+                          default=os.getenv("BITCOIND", "bitcoind"),
+                          help="bitcoind binary to test")
+
+    def setup_chain(self):
+        initialize_chain_clean(self.options.tmpdir, 2)
+
+    def setup_network(self):
+        # Node0 will be used to test behavior of processing unrequested blocks
+        # from peers which are not whitelisted, while Node1 will be used for
+        # the whitelisted case.
+        self.nodes = []
+        self.nodes.append(start_node(0, self.options.tmpdir, ["-debug"],
+                                     binary=self.options.testbinary))
+        self.nodes.append(start_node(1, self.options.tmpdir,
+                                     ["-debug", "-whitelist=127.0.0.1"],
+                                     binary=self.options.testbinary))
+
+    def run_test(self):
+        # Setup the p2p connections and start up the network thread.
+        test_node = TestNode()   # connects to node0 (not whitelisted)
+        white_node = TestNode()  # connects to node1 (whitelisted)
+
+        connections = []
+        connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], test_node))
+        connections.append(NodeConn('127.0.0.1', p2p_port(1), self.nodes[1], white_node))
+        test_node.add_connection(connections[0])
+        white_node.add_connection(connections[1])
+
+        NetworkThread().start() # Start up network handling in another thread
+
+        # Test logic begins here
+        test_node.wait_for_verack()
+        white_node.wait_for_verack()
+
+        # 1. Have both nodes mine a block (leave IBD)
+        [ n.generate(1) for n in self.nodes ]
+        tips = [ int ("0x" + n.getbestblockhash() + "L", 0) for n in self.nodes ]
+
+        # 2. Send one block that builds on each tip.
+        # This should be accepted.
+        blocks_h2 = []  # the height 2 blocks on each node's chain
+        for i in xrange(2):
+            blocks_h2.append(create_block(tips[i], create_coinbase(), time.time()+1))
+            blocks_h2[i].solve()
+        test_node.send_message(msg_block(blocks_h2[0]))
+        white_node.send_message(msg_block(blocks_h2[1]))
+
+        time.sleep(1)
+        assert_equal(self.nodes[0].getblockcount(), 2)
+        assert_equal(self.nodes[1].getblockcount(), 2)
+        print "First height 2 block accepted by both nodes"
+
+        # 3. Send another block that builds on the original tip.
+        blocks_h2f = []  # Blocks at height 2 that fork off the main chain
+        for i in xrange(2):
+            blocks_h2f.append(create_block(tips[i], create_coinbase(), blocks_h2[i].nTime+1))
+            blocks_h2f[i].solve()
+        test_node.send_message(msg_block(blocks_h2f[0]))
+        white_node.send_message(msg_block(blocks_h2f[1]))
+
+        time.sleep(1)  # Give time to process the block
+        for x in self.nodes[0].getchaintips():
+            if x['hash'] == blocks_h2f[0].hash:
+                assert_equal(x['status'], "headers-only")
+
+        for x in self.nodes[1].getchaintips():
+            if x['hash'] == blocks_h2f[1].hash:
+                assert_equal(x['status'], "valid-headers")
+
+        print "Second height 2 block accepted only from whitelisted peer"
+
+        # 4. Now send another block that builds on the forking chain.
+        blocks_h3 = []
+        for i in xrange(2):
+            blocks_h3.append(create_block(blocks_h2f[i].sha256, create_coinbase(), blocks_h2f[i].nTime+1))
+            blocks_h3[i].solve()
+        test_node.send_message(msg_block(blocks_h3[0]))
+        white_node.send_message(msg_block(blocks_h3[1]))
+
+        time.sleep(1)
+        # Since the earlier block was not processed by node0, the new block
+        # can't be fully validated.
+        for x in self.nodes[0].getchaintips():
+            if x['hash'] == blocks_h3[0].hash:
+                assert_equal(x['status'], "headers-only")
+
+        # But this block should be accepted by node0 since it has more work.
+        try:
+            self.nodes[0].getblock(blocks_h3[0].hash)
+            print "Unrequested more-work block accepted from non-whitelisted peer"
+        except:
+            raise AssertionError("Unrequested more work block was not processed")
+
+        # Node1 should have accepted and reorged.
+        assert_equal(self.nodes[1].getblockcount(), 3)
+        print "Successfully reorged to length 3 chain from whitelisted peer"
+
+        # 5. Test handling of unrequested block on the node that didn't process
+        # Should still not be processed (even though it has a child that has more
+        # work).
+        test_node.send_message(msg_block(blocks_h2f[0]))
+
+        # Here, if the sleep is too short, the test could falsely succeed (if the
+        # node hasn't processed the block by the time the sleep returns, and then
+        # the node processes it and incorrectly advances the tip).
+        # But this would be caught later on, when we verify that an inv triggers
+        # a getdata request for this block.
+        time.sleep(1)
+        assert_equal(self.nodes[0].getblockcount(), 2)
+        print "Unrequested block that would complete more-work chain was ignored"
+
+        # 6. Try to get node to request the missing block.
+        # Poke the node with an inv for block at height 3 and see if that
+        # triggers a getdata on block 2 (it should if block 2 is missing).
+        with mininode_lock:
+            # Clear state so we can check the getdata request
+            test_node.last_getdata = None
+            test_node.send_message(msg_inv([CInv(2, blocks_h3[0].sha256)]))
+
+        time.sleep(1)
+        with mininode_lock:
+            getdata = test_node.last_getdata
+
+        # Check that the getdata is for the right block
+        assert_equal(len(getdata.inv), 1)
+        assert_equal(getdata.inv[0].hash, blocks_h2f[0].sha256)
+        print "Inv at tip triggered getdata for unprocessed block"
+
+        # 7. Send the missing block for the third time (now it is requested)
+        test_node.send_message(msg_block(blocks_h2f[0]))
+
+        time.sleep(1)
+        assert_equal(self.nodes[0].getblockcount(), 3)
+        print "Successfully reorged to length 3 chain from non-whitelisted peer"
+
+        [ c.disconnect_node() for c in connections ]
+
+if __name__ == '__main__':
+    AcceptBlockTest().main()

src/main.cpp

@@ -296,7 +296,8 @@ void FinalizeNode(NodeId nodeid) {
 }
 
 // Requires cs_main.
-void MarkBlockAsReceived(const uint256& hash) {
+// Returns a bool indicating whether we requested this block.
+bool MarkBlockAsReceived(const uint256& hash) {
     map<uint256, pair<NodeId, list<QueuedBlock>::iterator> >::iterator itInFlight = mapBlocksInFlight.find(hash);
     if (itInFlight != mapBlocksInFlight.end()) {
         CNodeState *state = State(itInFlight->second.first);
@@ -306,7 +307,9 @@ void MarkBlockAsReceived(const uint256& hash) {
         state->nBlocksInFlight--;
         state->nStallingSince = 0;
         mapBlocksInFlight.erase(itInFlight);
+        return true;
     }
+    return false;
 }
 
 // Requires cs_main.
@@ -2826,7 +2829,7 @@ bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, CBloc
     return true;
 }
 
-bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex, CDiskBlockPos* dbp)
+bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex, bool fRequested, CDiskBlockPos* dbp)
 {
     const CChainParams& chainparams = Params();
     AssertLockHeld(cs_main);
@@ -2836,13 +2839,18 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
     if (!AcceptBlockHeader(block, state, &pindex))
         return false;
 
-    // If we're pruning, ensure that we don't allow a peer to dump a copy
-    // of old blocks.  But we might need blocks that are not on the main chain
-    // to handle a reorg, even if we've processed once.
-    if (pindex->nStatus & BLOCK_HAVE_DATA || chainActive.Contains(pindex)) {
-        // TODO: deal better with duplicate blocks.
-        // return state.DoS(20, error("AcceptBlock(): already have block %d %s", pindex->nHeight, pindex->GetBlockHash().ToString()), REJECT_DUPLICATE, "duplicate");
-        return true;
+    // Try to process all requested blocks that we don't have, but only
+    // process an unrequested block if it's new and has enough work to
+    // advance our tip.
+    bool fAlreadyHave = pindex->nStatus & BLOCK_HAVE_DATA;
+    bool fHasMoreWork = (chainActive.Tip() ? pindex->nChainWork > chainActive.Tip()->nChainWork : true);
+
+    // TODO: deal better with return value and error conditions for duplicate
+    // and unrequested blocks.
+    if (fAlreadyHave) return true;
+    if (!fRequested) {  // If we didn't ask for it:
+        if (pindex->nTx != 0) return true;  // This is a previously-processed block that was pruned
+        if (!fHasMoreWork) return true;     // Don't process less-work chains
     }
 
     if ((!CheckBlock(block, state)) || !ContextualCheckBlock(block, state, pindex->pprev)) {
@@ -2891,21 +2899,22 @@ static bool IsSuperMajority(int minVersion, const CBlockIndex* pstart, unsigned
 }
 
 
-bool ProcessNewBlock(CValidationState &state, CNode* pfrom, CBlock* pblock, CDiskBlockPos *dbp)
+bool ProcessNewBlock(CValidationState &state, CNode* pfrom, CBlock* pblock, bool fForceProcessing, CDiskBlockPos *dbp)
 {
     // Preliminary checks
     bool checked = CheckBlock(*pblock, state);
 
     {
         LOCK(cs_main);
-        MarkBlockAsReceived(pblock->GetHash());
+        bool fRequested = MarkBlockAsReceived(pblock->GetHash());
+        fRequested |= fForceProcessing;
         if (!checked) {
             return error("%s: CheckBlock FAILED", __func__);
         }
 
         // Store to disk
         CBlockIndex *pindex = NULL;
-        bool ret = AcceptBlock(*pblock, state, &pindex, dbp);
+        bool ret = AcceptBlock(*pblock, state, &pindex, fRequested, dbp);
         if (pindex && pfrom) {
             mapBlockSource[pindex->GetBlockHash()] = pfrom->GetId();
         }
@@ -3453,7 +3462,7 @@ bool LoadExternalBlockFile(FILE* fileIn, CDiskBlockPos *dbp)
                 // process in case the block isn't known yet
                 if (mapBlockIndex.count(hash) == 0 || (mapBlockIndex[hash]->nStatus & BLOCK_HAVE_DATA) == 0) {
                     CValidationState state;
-                    if (ProcessNewBlock(state, NULL, &block, dbp))
+                    if (ProcessNewBlock(state, NULL, &block, true, dbp))
                         nLoaded++;
                     if (state.IsError())
                         break;
@@ -3475,7 +3484,7 @@ bool LoadExternalBlockFile(FILE* fileIn, CDiskBlockPos *dbp)
                             LogPrintf("%s: Processing out of order child %s of %s\n", __func__, block.GetHash().ToString(),
                                     head.ToString());
                             CValidationState dummy;
-                            if (ProcessNewBlock(dummy, NULL, &block, &it->second))
+                            if (ProcessNewBlock(dummy, NULL, &block, true, &it->second))
                             {
                                 nLoaded++;
                                 queue.push_back(block.GetHash());
@@ -4462,7 +4471,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         pfrom->AddInventoryKnown(inv);
 
         CValidationState state;
-        ProcessNewBlock(state, pfrom, &block);
+        // Process all blocks from whitelisted peers, even if not requested.
+        ProcessNewBlock(state, pfrom, &block, pfrom->fWhitelisted, NULL);
         int nDoS;
         if (state.IsInvalid(nDoS)) {
             pfrom->PushMessage("reject", strCommand, state.GetRejectCode(),

src/main.h

@@ -153,10 +153,11 @@ void UnregisterNodeSignals(CNodeSignals& nodeSignals);
  * @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     If pblock is stored to disk (or already there), this will be set to its location.
  * @return True if state.IsValid()
  */
-bool ProcessNewBlock(CValidationState &state, CNode* pfrom, CBlock* pblock, CDiskBlockPos *dbp = NULL);
+bool ProcessNewBlock(CValidationState &state, CNode* pfrom, CBlock* pblock, bool fForceProcessing, CDiskBlockPos *dbp);
 /** Check whether enough disk space is available for an incoming block */
 bool CheckDiskSpace(uint64_t nAdditionalBytes = 0);
 /** Open a block file (blk?????.dat) */
@@ -400,8 +401,8 @@ bool ContextualCheckBlock(const CBlock& block, CValidationState& state, CBlockIn
 /** Check a block is completely valid from start to finish (only works on top of our current best block, with cs_main held) */
 bool TestBlockValidity(CValidationState &state, const CBlock& block, CBlockIndex *pindexPrev, bool fCheckPOW = true, bool fCheckMerkleRoot = true);
 
-/** Store block on disk. If dbp is provided, the file is known to already reside on disk */
-bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex **pindex, CDiskBlockPos* dbp = NULL);
+/** Store block on disk. If dbp is non-NULL, the file is known to already reside on disk */
+bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex **pindex, bool fRequested, CDiskBlockPos* dbp);
 bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex **ppindex= NULL);
 
 

src/miner.cpp

@@ -434,7 +434,7 @@ static bool ProcessBlockFound(CBlock* pblock, CWallet& wallet, CReserveKey& rese
 
     // Process this block the same as if we had received it from another node
     CValidationState state;
-    if (!ProcessNewBlock(state, NULL, pblock))
+    if (!ProcessNewBlock(state, NULL, pblock, true, NULL))
         return error("BitcoinMiner: ProcessNewBlock, block not accepted");
 
     return true;

src/rpcmining.cpp

@@ -164,7 +164,7 @@ Value generate(const Array& params, bool fHelp)
             ++pblock->nNonce;
         }
         CValidationState state;
-        if (!ProcessNewBlock(state, NULL, pblock))
+        if (!ProcessNewBlock(state, NULL, pblock, true, NULL))
             throw JSONRPCError(RPC_INTERNAL_ERROR, "ProcessNewBlock, block not accepted");
         ++nHeight;
         blockHashes.push_back(pblock->GetHash().GetHex());
@@ -650,7 +650,7 @@ Value submitblock(const Array& params, bool fHelp)
     CValidationState state;
     submitblock_StateCatcher sc(block.GetHash());
     RegisterValidationInterface(&sc);
-    bool fAccepted = ProcessNewBlock(state, NULL, &block);
+    bool fAccepted = ProcessNewBlock(state, NULL, &block, true, NULL);
     UnregisterValidationInterface(&sc);
     if (fBlockPresent)
     {