partial bitcoin#23706: getblockfrompeer followups

excludes:
- 8d1a3e6498de6087501969a9d243b0697ca3fe97
- 809d66bb65aa78048e27c2a878d6f7becaecfe11
- 60243cac7286e4c4bdda7094bef4cf6d1564b583

src/net_processing.cpp

@@ -398,7 +398,7 @@ public:
 
     /** Implement PeerManager */
     void CheckForStaleTipAndEvictPeers() override;
-    bool FetchBlock(NodeId id, const uint256& hash, const CBlockIndex& index) override;
+    std::optional<std::string> FetchBlock(NodeId peer_id, const CBlockIndex& block_index) override;
     bool GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) const override EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);
     bool IgnoresIncomingTxs() override { return m_ignore_incoming_txs; }
     void SendPings() override EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);;
@@ -1863,37 +1863,37 @@ bool PeerManagerImpl::BlockRequestAllowed(const CBlockIndex* pindex)
         (GetBlockProofEquivalentTime(*pindexBestHeader, *pindex, *pindexBestHeader, m_chainparams.GetConsensus()) < STALE_RELAY_AGE_LIMIT);
 }
 
-bool PeerManagerImpl::FetchBlock(NodeId id, const uint256& hash, const CBlockIndex& index)
+std::optional<std::string> PeerManagerImpl::FetchBlock(NodeId peer_id, const CBlockIndex& block_index)
 {
-    if (fImporting || fReindex) return false;
+    if (fImporting) return "Importing...";
+    if (fReindex) return "Reindexing...";
 
     LOCK(cs_main);
     // Ensure this peer exists and hasn't been disconnected
-    CNodeState* state = State(id);
+    CNodeState* state = State(peer_id);
-    if (state == nullptr) return false;
+    if (state == nullptr) return "Peer does not exist";
 
-    // Mark block as in-flight unless it already is
+    // Mark block as in-flight unless it already is (for this peer).
-    if (!MarkBlockAsInFlight(id, index.GetBlockHash(), &index)) return false;
+    // If a block was already in-flight for a different peer, its BLOCKTXN
+    // response will be dropped.
+    const uint256& hash{block_index.GetBlockHash()};
+    if (!MarkBlockAsInFlight(peer_id, hash, &block_index)) return "Already requested from this peer";
 
     // Construct message to request the block
     std::vector<CInv> invs{CInv(MSG_BLOCK, hash)};
 
     // Send block request message to the peer
-    bool success = m_connman.ForNode(id, [this, &invs](CNode* node) {
+    bool success = m_connman.ForNode(peer_id, [this, &invs](CNode* node) {
         const CNetMsgMaker msgMaker(node->GetCommonVersion());
         this->m_connman.PushMessage(node, msgMaker.Make(NetMsgType::GETDATA, invs));
         return true;
     });
 
-    if (success) {
+    if (!success) return "Peer not fully connected";
-        LogPrint(BCLog::NET, "Requesting block %s from peer=%d\n",
+
-                 hash.ToString(), id);
+    LogPrint(BCLog::NET, "Requesting block %s from peer=%d\n",
-    } else {
+                 hash.ToString(), peer_id);
-        MarkBlockAsReceived(hash);
+    return std::nullopt;
-        LogPrint(BCLog::NET, "Failed to request block %s from peer=%d\n",
-                 hash.ToString(), id);
-    }
-    return success;
 }
 
 std::unique_ptr<PeerManager> PeerManager::make(const CChainParams& chainparams, CConnman& connman, AddrMan& addrman, BanMan* banman,

src/net_processing.h

@@ -69,12 +69,11 @@ public:
     /**
      * Attempt to manually fetch block from a given peer. We must already have the header.
      *
-     * @param[in]  id       The peer id
+     * @param[in]  peer_id      The peer id
-     * @param[in]  hash     The block hash
+     * @param[in]  block_index  The blockindex
-     * @param[in]  pindex   The blockindex
+     * @returns std::nullopt if a request was successfully made, otherwise an error message
-     * @returns             Whether a request was successfully made
      */
-    virtual bool FetchBlock(NodeId id, const uint256& hash, const CBlockIndex& pindex) = 0;
+    virtual std::optional<std::string> FetchBlock(NodeId peer_id, const CBlockIndex& block_index) = 0;
 
     /** Get statistics from node state */
     virtual bool GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) const = 0;

src/rpc/blockchain.cpp

@@ -775,8 +775,8 @@ static RPCHelpMan getblockfrompeer()
         "\nWe must have the header for this block, e.g. using submitheader.\n"
         "\nReturns {} if a block-request was successfully scheduled\n",
         {
-            {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
+            {"block_hash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash to try to fetch"},
-            {"nodeid", RPCArg::Type::NUM, RPCArg::Optional::NO, "The node ID (see getpeerinfo for node IDs)"},
+            {"peer_id", RPCArg::Type::NUM, RPCArg::Optional::NO, "The peer to fetch it from (see getpeerinfo for peer IDs)"},
         },
         RPCResult{RPCResult::Type::OBJ, "", "",
         {
@@ -791,18 +791,11 @@ static RPCHelpMan getblockfrompeer()
     const NodeContext& node = EnsureAnyNodeContext(request.context);
     ChainstateManager& chainman = EnsureChainman(node);
     PeerManager& peerman = EnsurePeerman(node);
-    CConnman& connman = EnsureConnman(node);
 
-    uint256 hash(ParseHashV(request.params[0], "hash"));
+    const uint256& block_hash{ParseHashV(request.params[0], "block_hash")};
+    const NodeId peer_id{request.params[1].get_int64()};
 
-    const NodeId nodeid = static_cast<NodeId>(request.params[1].get_int64());
+    const CBlockIndex* const index = WITH_LOCK(cs_main, return chainman.m_blockman.LookupBlockIndex(block_hash););
-
-    // Check that the peer with nodeid exists
-    if (!connman.ForNode(nodeid, [](CNode* node) {return true;})) {
-        throw JSONRPCError(RPC_MISC_ERROR, strprintf("Peer nodeid %d does not exist", nodeid));
-    }
-
-    const CBlockIndex* const index = WITH_LOCK(cs_main, return chainman.m_blockman.LookupBlockIndex(hash););
 
     if (!index) {
         throw JSONRPCError(RPC_MISC_ERROR, "Block header missing");
@@ -812,8 +805,8 @@ static RPCHelpMan getblockfrompeer()
 
     if (index->nStatus & BLOCK_HAVE_DATA) {
         result.pushKV("warnings", "Block already downloaded");
-    } else if (!peerman.FetchBlock(nodeid, hash, *index)) {
+    } else if (const auto err{peerman.FetchBlock(peer_id, *index)}) {
-        throw JSONRPCError(RPC_MISC_ERROR, "Failed to fetch block from peer");
+        throw JSONRPCError(RPC_MISC_ERROR, err.value());
     }
     return result;
 },
@@ -3053,7 +3046,7 @@ static const CRPCCommand commands[] =
     { "blockchain",         "getbestchainlock",       &getbestchainlock,       {} },
     { "blockchain",         "getblockcount",          &getblockcount,          {} },
     { "blockchain",         "getblock",               &getblock,               {"blockhash","verbosity|verbose"} },
-    { "blockchain",         "getblockfrompeer",       &getblockfrompeer,       {"blockhash", "nodeid"}},
+    { "blockchain",         "getblockfrompeer",       &getblockfrompeer,       {"block_hash", "peer_id"}},
     { "blockchain",         "getblockhashes",         &getblockhashes,         {"high","low"} },
     { "blockchain",         "getblockhash",           &getblockhash,           {"height"} },
     { "blockchain",         "getblockheader",         &getblockheader,         {"blockhash","verbose"} },

src/rpc/client.cpp

@@ -66,7 +66,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "getbalance", 2, "addlocked" },
     { "getbalance", 3, "include_watchonly" },
     { "getbalance", 4, "avoid_reuse" },
-    { "getblockfrompeer", 1, "nodeid" },
+    { "getblockfrompeer", 1, "peer_id" },
     { "getchaintips", 0, "count" },
     { "getchaintips", 1, "branchlen" },
     { "getblockhash", 0, "height" },

test/functional/rpc_getblockfrompeer.py

@@ -40,12 +40,8 @@ class GetBlockFromPeerTest(BitcoinTestFramework):
         self.sync_blocks()
 
         self.log.info("Node 0 should only have the header for node 1's block 3")
-        for x in self.nodes[0].getchaintips():
+        x = next(filter(lambda x: x['hash'] == short_tip, self.nodes[0].getchaintips()))
-            if x['hash'] == short_tip:
+        assert_equal(x['status'], "headers-only")
-                assert_equal(x['status'], "headers-only")
-                break
-        else:
-            raise AssertionError("short tip not synced")
         assert_raises_rpc_error(-1, "Block not found on disk", self.nodes[0].getblock, short_tip)
 
         self.log.info("Fetch block from node 1")
@@ -60,7 +56,7 @@ class GetBlockFromPeerTest(BitcoinTestFramework):
         assert_raises_rpc_error(-1, "Block header missing", self.nodes[0].getblockfrompeer, "00" * 32, 0)
 
         self.log.info("Non-existent peer generates error")
-        assert_raises_rpc_error(-1, f"Peer nodeid {peer_0_peer_1_id + 1} does not exist", self.nodes[0].getblockfrompeer, short_tip, peer_0_peer_1_id + 1)
+        assert_raises_rpc_error(-1, "Peer does not exist", self.nodes[0].getblockfrompeer, short_tip, peer_0_peer_1_id + 1)
 
         self.log.info("Successful fetch")
         result = self.nodes[0].getblockfrompeer(short_tip, peer_0_peer_1_id)