Change in transaction pull scheduling to prevent InvBlock-related attacks
Co-authored-by: Suhas Daftuar <sdaftuar@gmail.com>
This commit is contained in:
parent
5029e94f85
commit
1cff3d6cb0
6 changed files with 168 additions and 81 deletions
36
src/net.cpp
36
src/net.cpp
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@ -85,8 +85,6 @@ std::map<CNetAddr, LocalServiceInfo> mapLocalHost GUARDED_BY(cs_mapLocalHost);
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static bool vfLimited[NET_MAX] GUARDED_BY(cs_mapLocalHost) = {};
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std::string strSubVersion;
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limitedmap<uint256, int64_t> mapAlreadyAskedFor(MAX_INV_SZ);
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void CConnman::AddOneShot(const std::string& strDest)
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{
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LOCK(cs_vOneShots);
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@ -2644,40 +2642,6 @@ CNode::~CNode()
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CloseSocket(hSocket);
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}
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void CNode::AskFor(const CInv& inv)
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{
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if (mapAskFor.size() > MAPASKFOR_MAX_SZ || setAskFor.size() > SETASKFOR_MAX_SZ)
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return;
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// a peer may not have multiple non-responded queue positions for a single inv item
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if (!setAskFor.insert(inv.hash).second)
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return;
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// We're using mapAskFor as a priority queue,
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// the key is the earliest time the request can be sent
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int64_t nRequestTime;
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limitedmap<uint256, int64_t>::const_iterator it = mapAlreadyAskedFor.find(inv.hash);
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if (it != mapAlreadyAskedFor.end())
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nRequestTime = it->second;
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else
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nRequestTime = 0;
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LogPrint(BCLog::NET, "askfor %s %d (%s) peer=%d\n", inv.ToString(), nRequestTime, FormatISO8601Time(nRequestTime/1000000), id);
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// Make sure not to reuse time indexes to keep things in the same order
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int64_t nNow = GetTimeMicros() - 1000000;
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static int64_t nLastTime;
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++nLastTime;
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nNow = std::max(nNow, nLastTime);
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nLastTime = nNow;
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// Each retry is 2 minutes after the last
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nRequestTime = std::max(nRequestTime + 2 * 60 * 1000000, nNow);
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if (it != mapAlreadyAskedFor.end())
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mapAlreadyAskedFor.update(it, nRequestTime);
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else
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mapAlreadyAskedFor.insert(std::make_pair(inv.hash, nRequestTime));
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mapAskFor.insert(std::make_pair(nRequestTime, inv));
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}
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bool CConnman::NodeFullyConnected(const CNode* pnode)
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{
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return pnode && pnode->fSuccessfullyConnected && !pnode->fDisconnect;
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10
src/net.h
10
src/net.h
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@ -67,10 +67,6 @@ static const bool DEFAULT_UPNP = USE_UPNP;
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#else
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static const bool DEFAULT_UPNP = false;
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#endif
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/** The maximum number of entries in mapAskFor */
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static const size_t MAPASKFOR_MAX_SZ = MAX_INV_SZ;
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/** The maximum number of entries in setAskFor (larger due to getdata latency)*/
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static const size_t SETASKFOR_MAX_SZ = 2 * MAX_INV_SZ;
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/** The maximum number of peer connections to maintain. */
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static const unsigned int DEFAULT_MAX_PEER_CONNECTIONS = 125;
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/** The default for -maxuploadtarget. 0 = Unlimited */
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@ -514,8 +510,6 @@ extern bool fDiscover;
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extern bool fListen;
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extern bool fRelayTxes;
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extern limitedmap<uint256, int64_t> mapAlreadyAskedFor;
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/** Subversion as sent to the P2P network in `version` messages */
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extern std::string strSubVersion;
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@ -704,8 +698,6 @@ public:
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// and in the order requested.
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std::vector<uint256> vInventoryBlockToSend GUARDED_BY(cs_inventory);
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CCriticalSection cs_inventory;
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std::set<uint256> setAskFor;
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std::multimap<int64_t, CInv> mapAskFor;
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int64_t nNextInvSend{0};
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// Used for headers announcements - unfiltered blocks to relay
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std::vector<uint256> vBlockHashesToAnnounce GUARDED_BY(cs_inventory);
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@ -852,8 +844,6 @@ public:
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vBlockHashesToAnnounce.push_back(hash);
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}
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void AskFor(const CInv& inv);
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void CloseSocketDisconnect();
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void copyStats(CNodeStats &stats);
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@ -64,6 +64,21 @@ static constexpr int STALE_RELAY_AGE_LIMIT = 30 * 24 * 60 * 60;
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/// Age after which a block is considered historical for purposes of rate
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/// limiting block relay. Set to one week, denominated in seconds.
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static constexpr int HISTORICAL_BLOCK_AGE = 7 * 24 * 60 * 60;
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/** Maximum number of in-flight transactions from a peer */
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static constexpr int32_t MAX_PEER_TX_IN_FLIGHT = 100;
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/** Maximum number of announced transactions from a peer */
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static constexpr int32_t MAX_PEER_TX_ANNOUNCEMENTS = 2 * MAX_INV_SZ;
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/** How many microseconds to delay requesting transactions from inbound peers */
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static constexpr int64_t INBOUND_PEER_TX_DELAY = 2 * 1000000;
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/** How long to wait (in microseconds) before downloading a transaction from an additional peer */
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static constexpr int64_t GETDATA_TX_INTERVAL = 60 * 1000000;
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/** Maximum delay (in microseconds) for transaction requests to avoid biasing some peers over others. */
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static constexpr int64_t MAX_GETDATA_RANDOM_DELAY = 2 * 1000000;
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static_assert(INBOUND_PEER_TX_DELAY >= MAX_GETDATA_RANDOM_DELAY,
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"To preserve security, MAX_GETDATA_RANDOM_DELAY should not exceed INBOUND_PEER_DELAY");
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/** Limit to avoid sending big packets. Not used in processing incoming GETDATA for compatibility */
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static const unsigned int MAX_GETDATA_SZ = 1000;
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struct COrphanTx {
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// When modifying, adapt the copy of this definition in tests/DoS_tests.
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@ -274,6 +289,66 @@ struct CNodeState {
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//! Time of last new block announcement
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int64_t m_last_block_announcement;
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/*
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* State associated with transaction download.
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*
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* Tx download algorithm:
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*
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* When inv comes in, queue up (process_time, txid) inside the peer's
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* CNodeState (m_tx_process_time) as long as m_tx_announced for the peer
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* isn't too big (MAX_PEER_TX_ANNOUNCEMENTS).
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*
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* The process_time for a transaction is set to nNow for outbound peers,
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* nNow + 2 seconds for inbound peers. This is the time at which we'll
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* consider trying to request the transaction from the peer in
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* SendMessages(). The delay for inbound peers is to allow outbound peers
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* a chance to announce before we request from inbound peers, to prevent
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* an adversary from using inbound connections to blind us to a
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* transaction (InvBlock).
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*
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* When we call SendMessages() for a given peer,
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* we will loop over the transactions in m_tx_process_time, looking
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* at the transactions whose process_time <= nNow. We'll request each
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* such transaction that we don't have already and that hasn't been
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* requested from another peer recently, up until we hit the
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* MAX_PEER_TX_IN_FLIGHT limit for the peer. Then we'll update
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* g_already_asked_for for each requested txid, storing the time of the
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* GETDATA request. We use g_already_asked_for to coordinate transaction
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* requests amongst our peers.
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*
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* For transactions that we still need but we have already recently
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* requested from some other peer, we'll reinsert (process_time, txid)
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* back into the peer's m_tx_process_time at the point in the future at
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* which the most recent GETDATA request would time out (ie
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* GETDATA_TX_INTERVAL + the request time stored in g_already_asked_for).
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* We add an additional delay for inbound peers, again to prefer
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* attempting download from outbound peers first.
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* We also add an extra small random delay up to 2 seconds
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* to avoid biasing some peers over others. (e.g., due to fixed ordering
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* of peer processing in ThreadMessageHandler).
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*
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* When we receive a transaction from a peer, we remove the txid from the
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* peer's m_tx_in_flight set and from their recently announced set
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* (m_tx_announced). We also clear g_already_asked_for for that entry, so
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* that if somehow the transaction is not accepted but also not added to
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* the reject filter, then we will eventually redownload from other
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* peers.
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*/
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struct TxDownloadState {
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/* Track when to attempt download of announced transactions (process
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* time in micros -> txid)
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*/
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std::multimap<int64_t, uint256> m_tx_process_time;
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//! Store all the transactions a peer has recently announced
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std::set<uint256> m_tx_announced;
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//! Store transactions which were requested by us
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std::set<uint256> m_tx_in_flight;
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};
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TxDownloadState m_tx_download;
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CNodeState(CAddress addrIn, std::string addrNameIn) : address(addrIn), name(addrNameIn) {
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fCurrentlyConnected = false;
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nMisbehavior = 0;
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@ -301,6 +376,9 @@ struct CNodeState {
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}
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};
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// Keeps track of the time (in microseconds) when transactions were requested last time
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limitedmap<uint256, int64_t> g_already_asked_for GUARDED_BY(cs_main)(MAX_INV_SZ);
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/** Map maintaining per-node state. */
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static std::map<NodeId, CNodeState> mapNodeState GUARDED_BY(cs_main);
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@ -591,6 +669,58 @@ static void FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vec
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}
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}
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void EraseTxRequest(const uint256& txid) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
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{
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g_already_asked_for.erase(txid);
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}
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int64_t GetTxRequestTime(const uint256& txid) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
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{
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auto it = g_already_asked_for.find(txid);
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if (it != g_already_asked_for.end()) {
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return it->second;
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}
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return 0;
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}
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void UpdateTxRequestTime(const uint256& txid, int64_t request_time) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
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{
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auto it = g_already_asked_for.find(txid);
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if (it == g_already_asked_for.end()) {
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g_already_asked_for.insert(std::make_pair(txid, request_time));
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} else {
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g_already_asked_for.update(it, request_time);
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}
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}
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void RequestTx(CNodeState* state, const uint256& txid, int64_t nNow) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
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{
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CNodeState::TxDownloadState& peer_download_state = state->m_tx_download;
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if (peer_download_state.m_tx_announced.size() >= MAX_PEER_TX_ANNOUNCEMENTS || peer_download_state.m_tx_announced.count(txid)) {
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// Too many queued announcements from this peer, or we already have
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// this announcement
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return;
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}
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peer_download_state.m_tx_announced.insert(txid);
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int64_t process_time;
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int64_t last_request_time = GetTxRequestTime(txid);
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// First time requesting this tx
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if (last_request_time == 0) {
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process_time = nNow;
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} else {
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// Randomize the delay to avoid biasing some peers over others (such as due to
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// fixed ordering of peer processing in ThreadMessageHandler)
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process_time = last_request_time + GETDATA_TX_INTERVAL + GetRand(MAX_GETDATA_RANDOM_DELAY);
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}
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// We delay processing announcements from non-preferred (eg inbound) peers
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if (!state->fPreferredDownload) process_time += INBOUND_PEER_TX_DELAY;
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peer_download_state.m_tx_process_time.emplace(process_time, txid);
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}
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} // namespace
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// This function is used for testing the stale tip eviction logic, see
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@ -1945,6 +2075,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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LOCK(cs_main);
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uint32_t nFetchFlags = GetFetchFlags(pfrom);
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int64_t nNow = GetTimeMicros();
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for (CInv &inv : vInv)
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{
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@ -1976,7 +2107,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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if (fBlocksOnly) {
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LogPrint(BCLog::NET, "transaction (%s) inv sent in violation of protocol peer=%d\n", inv.hash.ToString(), pfrom->GetId());
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} else if (!fAlreadyHave && !fImporting && !fReindex && !IsInitialBlockDownload()) {
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pfrom->AskFor(inv);
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RequestTx(State(pfrom->GetId()), inv.hash, nNow);
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}
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}
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}
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@ -2211,8 +2342,10 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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bool fMissingInputs = false;
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CValidationState state;
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pfrom->setAskFor.erase(inv.hash);
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mapAlreadyAskedFor.erase(inv.hash);
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CNodeState* nodestate = State(pfrom->GetId());
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nodestate->m_tx_download.m_tx_announced.erase(inv.hash);
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nodestate->m_tx_download.m_tx_in_flight.erase(inv.hash);
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EraseTxRequest(inv.hash);
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std::list<CTransactionRef> lRemovedTxn;
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@ -2303,10 +2436,12 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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}
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if (!fRejectedParents) {
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uint32_t nFetchFlags = GetFetchFlags(pfrom);
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int64_t nNow = GetTimeMicros();
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for (const CTxIn& txin : tx.vin) {
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CInv _inv(MSG_TX | nFetchFlags, txin.prevout.hash);
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pfrom->AddInventoryKnown(_inv);
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if (!AlreadyHave(_inv)) pfrom->AskFor(_inv);
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if (!AlreadyHave(_inv)) RequestTx(State(pfrom->GetId()), _inv.hash, nNow);
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}
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AddOrphanTx(ptx, pfrom->GetId());
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@ -3731,24 +3866,39 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
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//
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// Message: getdata (non-blocks)
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//
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while (!pto->mapAskFor.empty() && (*pto->mapAskFor.begin()).first <= nNow)
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{
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const CInv& inv = (*pto->mapAskFor.begin()).second;
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if (!AlreadyHave(inv))
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{
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LogPrint(BCLog::NET, "Requesting %s peer=%d\n", inv.ToString(), pto->GetId());
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vGetData.push_back(inv);
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if (vGetData.size() >= 1000)
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{
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connman->PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
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vGetData.clear();
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auto& tx_process_time = state.m_tx_download.m_tx_process_time;
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while (!tx_process_time.empty() && tx_process_time.begin()->first <= nNow && state.m_tx_download.m_tx_in_flight.size() < MAX_PEER_TX_IN_FLIGHT) {
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const uint256& txid = tx_process_time.begin()->second;
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CInv inv(MSG_TX | GetFetchFlags(pto), txid);
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if (!AlreadyHave(inv)) {
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// If this transaction was last requested more than 1 minute ago,
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// then request.
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int64_t last_request_time = GetTxRequestTime(inv.hash);
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if (last_request_time <= nNow - GETDATA_TX_INTERVAL) {
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LogPrint(BCLog::NET, "Requesting %s peer=%d\n", inv.ToString(), pto->GetId());
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vGetData.push_back(inv);
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if (vGetData.size() >= MAX_GETDATA_SZ) {
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connman->PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
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vGetData.clear();
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}
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UpdateTxRequestTime(inv.hash, nNow);
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state.m_tx_download.m_tx_in_flight.insert(inv.hash);
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} else {
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// This transaction is in flight from someone else; queue
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// up processing to happen after the download times out
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// (with a slight delay for inbound peers, to prefer
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// requests to outbound peers).
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RequestTx(&state, txid, nNow);
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}
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} else {
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//If we're not going to ask, don't expect a response.
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pto->setAskFor.erase(inv.hash);
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// We have already seen this transaction, no need to download.
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state.m_tx_download.m_tx_announced.erase(inv.hash);
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state.m_tx_download.m_tx_in_flight.erase(inv.hash);
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}
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pto->mapAskFor.erase(pto->mapAskFor.begin());
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tx_process_time.erase(tx_process_time.begin());
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}
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if (!vGetData.empty())
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connman->PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
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@ -169,11 +169,6 @@ BOOST_AUTO_TEST_CASE(util_FormatISO8601Date)
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BOOST_CHECK_EQUAL(FormatISO8601Date(1317425777), "2011-09-30");
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}
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BOOST_AUTO_TEST_CASE(util_FormatISO8601Time)
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{
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BOOST_CHECK_EQUAL(FormatISO8601Time(1317425777), "23:36:17Z");
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}
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struct TestArgsManager : public ArgsManager
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{
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TestArgsManager() { m_network_only_args.clear(); }
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@ -97,14 +97,3 @@ std::string FormatISO8601Date(int64_t nTime) {
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#endif
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return strprintf("%04i-%02i-%02i", ts.tm_year + 1900, ts.tm_mon + 1, ts.tm_mday);
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}
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std::string FormatISO8601Time(int64_t nTime) {
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struct tm ts;
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time_t time_val = nTime;
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#ifdef _MSC_VER
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gmtime_s(&ts, &time_val);
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#else
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gmtime_r(&time_val, &ts);
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#endif
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return strprintf("%02i:%02i:%02iZ", ts.tm_hour, ts.tm_min, ts.tm_sec);
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}
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@ -33,6 +33,5 @@ void MilliSleep(int64_t n);
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*/
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std::string FormatISO8601DateTime(int64_t nTime);
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std::string FormatISO8601Date(int64_t nTime);
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std::string FormatISO8601Time(int64_t nTime);
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#endif // BITCOIN_UTIL_TIME_H
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