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Merge #15759: p2p: Add 2 outbound block-relay-only connections

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0ba08020c9 Disconnect peers violating blocks-only mode (Suhas Daftuar)
937eba91e1 doc: improve comments relating to block-relay-only peers (Suhas Daftuar)
430f489027 Don't relay addr messages to block-relay-only peers (Suhas Daftuar)
3a5e885306 Add 2 outbound block-relay-only connections (Suhas Daftuar)
b83f51a4bb Add comment explaining intended use of m_tx_relay (Suhas Daftuar)
e75c39cd42 Check that tx_relay is initialized before access (Suhas Daftuar)
c4aa2ba822 [refactor] Change tx_relay structure to be unique_ptr (Suhas Daftuar)
4de0dbac9b [refactor] Move tx relay state to separate structure (Suhas Daftuar)
26a93bce29 Remove unused variable (Suhas Daftuar)

Pull request description:

  Transaction relay is optimized for a combination of redundancy/robustness as well as bandwidth minimization -- as a result transaction relay leaks information that adversaries can use to infer the network topology.

  Network topology is better kept private for (at least) two reasons:

  (a) Knowledge of the network graph can make it easier to find the source IP of a given transaction.

  (b) Knowledge of the network graph could be used to split a target node or nodes from the honest network (eg by knowing which peers to attack in order to achieve a network split).

  We can eliminate the risks of (b) by separating block relay from transaction relay; inferring network connectivity from the relay of blocks/block headers is much more expensive for an adversary.

  After this commit, bitcoind will make 2 additional outbound connections that are only used for block relay. (In the future, we might consider rotating our transaction-relay peers to help limit the effects of (a).)

ACKs for top commit:
  sipa:
    ACK 0ba08020c9
  ajtowns:
    ACK 0ba08020c9 -- code review, ran tests. ran it on mainnet for a couple of days with MAX_BLOCKS_ONLY_CONNECTIONS upped from 2 to 16 and didn't observe any unexpected behaviour: it disconnected a couple of peers that tried sending inv's, and it successfully did compact block relay with some block relay peers.
  TheBlueMatt:
    re-utACK 0ba08020c9. Pointed out that stats.fRelayTxes was sometimes uninitialized for blocksonly peers (though its not a big deal and only effects RPC), which has since been fixed here. Otherwise changes are pretty trivial so looks good.
  jnewbery:
    utACK 0ba08020c9
  jamesob:
    ACK 0ba08020c9

Tree-SHA512: 4c3629434472c7dd4125253417b1be41967a508c3cfec8af5a34cad685464fbebbb6558f0f8f5c0d4463e3ffa4fa3aabd58247692cb9ab8395f4993078b9bcdf
This commit is contained in:
fanquake
2019-09-07 17:24:05 +08:00
parent b5a8d0cff1 0ba08020c9
commit 189c19e012
6 changed files with 318 additions and 231 deletions
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107
src/net.h
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@@ -61,10 +61,12 @@ static const unsigned int MAX_ADDR_TO_SEND = 1000;
static const unsigned int MAX_PROTOCOL_MESSAGE_LENGTH = 4 * 1000 * 1000;
/** Maximum length of the user agent string in `version` message */
static const unsigned int MAX_SUBVERSION_LENGTH = 256;
/** Maximum number of automatic outgoing nodes */
static const int MAX_OUTBOUND_CONNECTIONS = 8;
/** Maximum number of automatic outgoing nodes over which we'll relay everything (blocks, tx, addrs, etc) */
static const int MAX_OUTBOUND_FULL_RELAY_CONNECTIONS = 8;
/** Maximum number of addnode outgoing nodes */
static const int MAX_ADDNODE_CONNECTIONS = 8;
/** Maximum number of block-relay-only outgoing connections */
static const int MAX_BLOCKS_ONLY_CONNECTIONS = 2;
/** -listen default */
static const bool DEFAULT_LISTEN = true;
/** -upnp default */
@@ -131,7 +133,8 @@ public:
{
ServiceFlags nLocalServices = NODE_NONE;
int nMaxConnections = 0;
int nMaxOutbound = 0;
int m_max_outbound_full_relay = 0;
int m_max_outbound_block_relay = 0;
int nMaxAddnode = 0;
int nMaxFeeler = 0;
int nBestHeight = 0;
@@ -155,10 +158,12 @@ public:
void Init(const Options& connOptions) {
nLocalServices = connOptions.nLocalServices;
nMaxConnections = connOptions.nMaxConnections;
nMaxOutbound = std::min(connOptions.nMaxOutbound, connOptions.nMaxConnections);
m_max_outbound_full_relay = std::min(connOptions.m_max_outbound_full_relay, connOptions.nMaxConnections);
m_max_outbound_block_relay = connOptions.m_max_outbound_block_relay;
m_use_addrman_outgoing = connOptions.m_use_addrman_outgoing;
nMaxAddnode = connOptions.nMaxAddnode;
nMaxFeeler = connOptions.nMaxFeeler;
m_max_outbound = m_max_outbound_full_relay + m_max_outbound_block_relay + nMaxFeeler;
nBestHeight = connOptions.nBestHeight;
clientInterface = connOptions.uiInterface;
m_banman = connOptions.m_banman;
@@ -197,7 +202,7 @@ public:
bool GetNetworkActive() const { return fNetworkActive; };
bool GetUseAddrmanOutgoing() const { return m_use_addrman_outgoing; };
void SetNetworkActive(bool active);
void OpenNetworkConnection(const CAddress& addrConnect, bool fCountFailure, CSemaphoreGrant *grantOutbound = nullptr, const char *strDest = nullptr, bool fOneShot = false, bool fFeeler = false, bool manual_connection = false);
void OpenNetworkConnection(const CAddress& addrConnect, bool fCountFailure, CSemaphoreGrant *grantOutbound = nullptr, const char *strDest = nullptr, bool fOneShot = false, bool fFeeler = false, bool manual_connection = false, bool block_relay_only = false);
bool CheckIncomingNonce(uint64_t nonce);
bool ForNode(NodeId id, std::function<bool(CNode* pnode)> func);
@@ -253,7 +258,7 @@ public:
void AddNewAddresses(const std::vector<CAddress>& vAddr, const CAddress& addrFrom, int64_t nTimePenalty = 0);
std::vector<CAddress> GetAddresses();
// This allows temporarily exceeding nMaxOutbound, with the goal of finding
// This allows temporarily exceeding m_max_outbound_full_relay, with the goal of finding
// a peer that is better than all our current peers.
void SetTryNewOutboundPeer(bool flag);
bool GetTryNewOutboundPeer();
@@ -355,7 +360,7 @@ private:
CNode* FindNode(const CService& addr);
bool AttemptToEvictConnection();
CNode* ConnectNode(CAddress addrConnect, const char *pszDest, bool fCountFailure, bool manual_connection);
CNode* ConnectNode(CAddress addrConnect, const char *pszDest, bool fCountFailure, bool manual_connection, bool block_relay_only);
void AddWhitelistPermissionFlags(NetPermissionFlags& flags, const CNetAddr &addr) const;
void DeleteNode(CNode* pnode);
@@ -414,9 +419,17 @@ private:
std::unique_ptr<CSemaphore> semOutbound;
std::unique_ptr<CSemaphore> semAddnode;
int nMaxConnections;
int nMaxOutbound;
// How many full-relay (tx, block, addr) outbound peers we want
int m_max_outbound_full_relay;
// How many block-relay only outbound peers we want
// We do not relay tx or addr messages with these peers
int m_max_outbound_block_relay;
int nMaxAddnode;
int nMaxFeeler;
int m_max_outbound;
bool m_use_addrman_outgoing;
std::atomic<int> nBestHeight;
CClientUIInterface* clientInterface;
@@ -442,7 +455,7 @@ private:
std::thread threadMessageHandler;
/** flag for deciding to connect to an extra outbound peer,
* in excess of nMaxOutbound
* in excess of m_max_outbound_full_relay
* This takes the place of a feeler connection */
std::atomic_bool m_try_another_outbound_peer;
@@ -681,15 +694,8 @@ public:
// Setting fDisconnect to true will cause the node to be disconnected the
// next time DisconnectNodes() runs
std::atomic_bool fDisconnect{false};
// We use fRelayTxes for two purposes -
// a) it allows us to not relay tx invs before receiving the peer's version message
// b) the peer may tell us in its version message that we should not relay tx invs
// unless it loads a bloom filter.
bool fRelayTxes GUARDED_BY(cs_filter){false};
bool fSentAddr{false};
CSemaphoreGrant grantOutbound;
mutable CCriticalSection cs_filter;
std::unique_ptr<CBloomFilter> pfilter PT_GUARDED_BY(cs_filter);
std::atomic<int> nRefCount{0};
const uint64_t nKeyedNetGroup;
@@ -708,28 +714,51 @@ public:
std::vector<CAddress> vAddrToSend;
CRollingBloomFilter addrKnown;
bool fGetAddr{false};
std::set<uint256> setKnown;
int64_t nNextAddrSend GUARDED_BY(cs_sendProcessing){0};
int64_t nNextLocalAddrSend GUARDED_BY(cs_sendProcessing){0};
// inventory based relay
CRollingBloomFilter filterInventoryKnown GUARDED_BY(cs_inventory);
// Set of transaction ids we still have to announce.
// They are sorted by the mempool before relay, so the order is not important.
std::set<uint256> setInventoryTxToSend;
const bool m_addr_relay_peer;
bool IsAddrRelayPeer() const { return m_addr_relay_peer; }
// List of block ids we still have announce.
// There is no final sorting before sending, as they are always sent immediately
// and in the order requested.
std::vector<uint256> vInventoryBlockToSend GUARDED_BY(cs_inventory);
CCriticalSection cs_inventory;
int64_t nNextInvSend{0};
struct TxRelay {
TxRelay() { pfilter = MakeUnique<CBloomFilter>(); }
mutable CCriticalSection cs_filter;
// We use fRelayTxes for two purposes -
// a) it allows us to not relay tx invs before receiving the peer's version message
// b) the peer may tell us in its version message that we should not relay tx invs
// unless it loads a bloom filter.
bool fRelayTxes GUARDED_BY(cs_filter){false};
std::unique_ptr<CBloomFilter> pfilter PT_GUARDED_BY(cs_filter) GUARDED_BY(cs_filter);
mutable CCriticalSection cs_tx_inventory;
CRollingBloomFilter filterInventoryKnown GUARDED_BY(cs_tx_inventory){50000, 0.000001};
// Set of transaction ids we still have to announce.
// They are sorted by the mempool before relay, so the order is not important.
std::set<uint256> setInventoryTxToSend;
// Used for BIP35 mempool sending
bool fSendMempool GUARDED_BY(cs_tx_inventory){false};
// Last time a "MEMPOOL" request was serviced.
std::atomic<int64_t> timeLastMempoolReq{0};
int64_t nNextInvSend{0};
CCriticalSection cs_feeFilter;
// Minimum fee rate with which to filter inv's to this node
CAmount minFeeFilter GUARDED_BY(cs_feeFilter){0};
CAmount lastSentFeeFilter{0};
int64_t nextSendTimeFeeFilter{0};
};
// m_tx_relay == nullptr if we're not relaying transactions with this peer
std::unique_ptr<TxRelay> m_tx_relay;
// Used for headers announcements - unfiltered blocks to relay
std::vector<uint256> vBlockHashesToAnnounce GUARDED_BY(cs_inventory);
// Used for BIP35 mempool sending
bool fSendMempool GUARDED_BY(cs_inventory){false};
// Last time a "MEMPOOL" request was serviced.
std::atomic<int64_t> timeLastMempoolReq{0};
// Block and TXN accept times
std::atomic<int64_t> nLastBlockTime{0};
@@ -746,15 +775,10 @@ public:
std::atomic<int64_t> nMinPingUsecTime{std::numeric_limits<int64_t>::max()};
// Whether a ping is requested.
std::atomic<bool> fPingQueued{false};
// Minimum fee rate with which to filter inv's to this node
CAmount minFeeFilter GUARDED_BY(cs_feeFilter){0};
CCriticalSection cs_feeFilter;
CAmount lastSentFeeFilter{0};
int64_t nextSendTimeFeeFilter{0};
std::set<uint256> orphan_work_set;
CNode(NodeId id, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn, SOCKET hSocketIn, const CAddress &addrIn, uint64_t nKeyedNetGroupIn, uint64_t nLocalHostNonceIn, const CAddress &addrBindIn, const std::string &addrNameIn = "", bool fInboundIn = false);
CNode(NodeId id, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn, SOCKET hSocketIn, const CAddress &addrIn, uint64_t nKeyedNetGroupIn, uint64_t nLocalHostNonceIn, const CAddress &addrBindIn, const std::string &addrNameIn = "", bool fInboundIn = false, bool block_relay_only = false);
~CNode();
CNode(const CNode&) = delete;
CNode& operator=(const CNode&) = delete;
@@ -847,20 +871,21 @@ public:
void AddInventoryKnown(const CInv& inv)
{
{
LOCK(cs_inventory);
filterInventoryKnown.insert(inv.hash);
if (m_tx_relay != nullptr) {
LOCK(m_tx_relay->cs_tx_inventory);
m_tx_relay->filterInventoryKnown.insert(inv.hash);
}
}
void PushInventory(const CInv& inv)
{
LOCK(cs_inventory);
if (inv.type == MSG_TX) {
if (!filterInventoryKnown.contains(inv.hash)) {
setInventoryTxToSend.insert(inv.hash);
if (inv.type == MSG_TX && m_tx_relay != nullptr) {
LOCK(m_tx_relay->cs_tx_inventory);
if (!m_tx_relay->filterInventoryKnown.contains(inv.hash)) {
m_tx_relay->setInventoryTxToSend.insert(inv.hash);
}
} else if (inv.type == MSG_BLOCK) {
LOCK(cs_inventory);
vInventoryBlockToSend.push_back(inv.hash);
}
}