backport: bitcoin#17428, #17785, #19109, #19610, #19804, #19879, #20022, #20027, #20090, #20131

src/coinjoin/client.cpp

@@ -666,7 +666,7 @@ bool CCoinJoinClientSession::SignFinalTransaction(const CTxMemPool& mempool, con
 
     // push all of our signatures to the Masternode
     WalletCJLogPrint(m_wallet, "CCoinJoinClientSession::%s -- pushing signed inputs to the masternode, finalMutableTransaction=%s", __func__, finalMutableTransaction.ToString()); /* Continued */
-    CNetMsgMaker msgMaker(peer.GetSendVersion());
+    CNetMsgMaker msgMaker(peer.GetCommonVersion());
     connman.PushMessage(&peer, msgMaker.Make(NetMsgType::DSSIGNFINALTX, signed_inputs));
     SetState(POOL_STATE_SIGNING);
     nTimeLastSuccessfulStep = GetTime();
@@ -1201,7 +1201,7 @@ bool CCoinJoinClientSession::ProcessPendingDsaRequest(CConnman& connman)
     bool fDone = connman.ForNode(pendingDsaRequest.GetAddr(), [this, &connman](CNode* pnode) {
         WalletCJLogPrint(m_wallet, "-- processing dsa queue for addr=%s\n", pnode->addr.ToString());
         nTimeLastSuccessfulStep = GetTime();
-        CNetMsgMaker msgMaker(pnode->GetSendVersion());
+        CNetMsgMaker msgMaker(pnode->GetCommonVersion());
         connman.PushMessage(pnode, msgMaker.Make(NetMsgType::DSACCEPT, pendingDsaRequest.GetDSA()));
         return true;
     });
@@ -1809,7 +1809,7 @@ void CCoinJoinClientSession::RelayIn(const CCoinJoinEntry& entry, CConnman& conn
 
     connman.ForNode(mixingMasternode->pdmnState->addr, [&entry, &connman, this](CNode* pnode) {
         WalletCJLogPrint(m_wallet, "CCoinJoinClientSession::RelayIn -- found master, relaying message to %s\n", pnode->addr.ToString());
-        CNetMsgMaker msgMaker(pnode->GetSendVersion());
+        CNetMsgMaker msgMaker(pnode->GetCommonVersion());
         connman.PushMessage(pnode, msgMaker.Make(NetMsgType::DSVIN, entry));
         return true;
     });

src/coinjoin/coinjoin.cpp

@@ -74,7 +74,7 @@ bool CCoinJoinQueue::CheckSignature(const CBLSPublicKey& blsPubKey) const
 bool CCoinJoinQueue::Relay(CConnman& connman)
 {
     connman.ForEachNode([&connman, this](CNode* pnode) {
-        CNetMsgMaker msgMaker(pnode->GetSendVersion());
+        CNetMsgMaker msgMaker(pnode->GetCommonVersion());
         if (pnode->fSendDSQueue) {
             connman.PushMessage(pnode, msgMaker.Make(NetMsgType::DSQUEUE, (*this)));
         }

src/coinjoin/server.cpp

@@ -794,7 +794,7 @@ void CCoinJoinServer::RelayFinalTransaction(const CTransaction& txFinal)
     // final mixing tx with empty signatures should be relayed to mixing participants only
     for (const auto& entry : vecEntries) {
         bool fOk = connman.ForNode(entry.addr, [&txFinal, this](CNode* pnode) {
-            CNetMsgMaker msgMaker(pnode->GetSendVersion());
+            CNetMsgMaker msgMaker(pnode->GetCommonVersion());
             connman.PushMessage(pnode, msgMaker.Make(NetMsgType::DSFINALTX, nSessionID.load(), txFinal));
             return true;
         });
@@ -809,7 +809,7 @@ void CCoinJoinServer::RelayFinalTransaction(const CTransaction& txFinal)
 void CCoinJoinServer::PushStatus(CNode& peer, PoolStatusUpdate nStatusUpdate, PoolMessage nMessageID) const
 {
     CCoinJoinStatusUpdate psssup(nSessionID, nState, 0, nStatusUpdate, nMessageID);
-    connman.PushMessage(&peer, CNetMsgMaker(peer.GetSendVersion()).Make(NetMsgType::DSSTATUSUPDATE, psssup));
+    connman.PushMessage(&peer, CNetMsgMaker(peer.GetCommonVersion()).Make(NetMsgType::DSSTATUSUPDATE, psssup));
 }
 
 void CCoinJoinServer::RelayStatus(PoolStatusUpdate nStatusUpdate, PoolMessage nMessageID)
@@ -859,7 +859,7 @@ void CCoinJoinServer::RelayCompletedTransaction(PoolMessage nMessageID)
     LOCK(cs_coinjoin);
     for (const auto& entry : vecEntries) {
         bool fOk = connman.ForNode(entry.addr, [&nMessageID, this](CNode* pnode) {
-            CNetMsgMaker msgMaker(pnode->GetSendVersion());
+            CNetMsgMaker msgMaker(pnode->GetCommonVersion());
             connman.PushMessage(pnode, msgMaker.Make(NetMsgType::DSCOMPLETE, nSessionID.load(), nMessageID));
             return true;
         });

src/evo/mnauth.cpp

@@ -55,7 +55,7 @@ void CMNAuth::PushMNAUTH(CNode& peer, CConnman& connman, const CBlockIndex* tip)
 
     LogPrint(BCLog::NET_NETCONN, "CMNAuth::%s -- Sending MNAUTH, peer=%d\n", __func__, peer.GetId());
 
-    connman.PushMessage(&peer, CNetMsgMaker(peer.GetSendVersion()).Make(NetMsgType::MNAUTH, mnauth));
+    connman.PushMessage(&peer, CNetMsgMaker(peer.GetCommonVersion()).Make(NetMsgType::MNAUTH, mnauth));
 }
 
 PeerMsgRet CMNAuth::ProcessMessage(CNode& peer, CConnman& connman, std::string_view msg_type, CDataStream& vRecv)
@@ -180,7 +180,7 @@ PeerMsgRet CMNAuth::ProcessMessage(CNode& peer, CConnman& connman, std::string_v
         // Otherwise, the peer would only announce/send messages resulting from QRECSIG,
         // e.g. InstantSend locks or ChainLocks. SPV and regular full nodes should not send
         // this message as they are usually only interested in the higher level messages.
-        const CNetMsgMaker msgMaker(peer.GetSendVersion());
+        const CNetMsgMaker msgMaker(peer.GetCommonVersion());
         connman.PushMessage(&peer, msgMaker.Make(NetMsgType::QSENDRECSIGS, true));
         peer.m_masternode_iqr_connection = true;
     }

src/governance/governance.cpp

@@ -890,7 +890,7 @@ void CGovernanceManager::SyncSingleObjVotes(CNode& peer, const uint256& nProp, c
         ++nVoteCount;
     }
 
-    CNetMsgMaker msgMaker(peer.GetSendVersion());
+    CNetMsgMaker msgMaker(peer.GetCommonVersion());
     connman.PushMessage(&peer, msgMaker.Make(NetMsgType::SYNCSTATUSCOUNT, MASTERNODE_SYNC_GOVOBJ_VOTE, nVoteCount));
     LogPrint(BCLog::GOBJECT, "CGovernanceManager::%s -- sent %d votes to peer=%d\n", __func__, nVoteCount, peer.GetId());
 }
@@ -948,7 +948,7 @@ PeerMsgRet CGovernanceManager::SyncObjects(CNode& peer, CConnman& connman) const
         ++nObjCount;
     }
 
-    CNetMsgMaker msgMaker(peer.GetSendVersion());
+    CNetMsgMaker msgMaker(peer.GetCommonVersion());
     connman.PushMessage(&peer, msgMaker.Make(NetMsgType::SYNCSTATUSCOUNT, MASTERNODE_SYNC_GOVOBJ, nObjCount));
     LogPrint(BCLog::GOBJECT, "CGovernanceManager::%s -- sent %d objects to peer=%d\n", __func__, nObjCount, peer.GetId());
     return {};
@@ -1173,7 +1173,7 @@ void CGovernanceManager::RequestGovernanceObject(CNode* pfrom, const uint256& nH
 
     LogPrint(BCLog::GOBJECT, "CGovernanceManager::RequestGovernanceObject -- nHash %s peer=%d\n", nHash.ToString(), pfrom->GetId());
 
-    CNetMsgMaker msgMaker(pfrom->GetSendVersion());
+    CNetMsgMaker msgMaker(pfrom->GetCommonVersion());
 
     CBloomFilter filter;
 

src/llmq/quorums.cpp

@@ -481,7 +481,7 @@ bool CQuorumManager::RequestQuorumData(CNode* pfrom, Consensus::LLMQType llmqTyp
     LogPrint(BCLog::LLMQ, "CQuorumManager::%s -- sending QGETDATA quorumHash[%s] llmqType[%d] proRegTx[%s]\n", __func__, key.quorumHash.ToString(),
              ToUnderlying(key.llmqType), key.proRegTx.ToString());
 
-    CNetMsgMaker msgMaker(pfrom->GetSendVersion());
+    CNetMsgMaker msgMaker(pfrom->GetCommonVersion());
     connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::QGETDATA, request));
 
     return true;
@@ -682,8 +682,8 @@ PeerMsgRet CQuorumManager::ProcessMessage(CNode& pfrom, const std::string& msg_t
                     break;
             }
             request.SetError(nError);
-            CDataStream ssResponse(SER_NETWORK, pfrom.GetSendVersion(), request, body);
-            connman.PushMessage(&pfrom, CNetMsgMaker(pfrom.GetSendVersion()).Make(NetMsgType::QDATA, ssResponse));
+            CDataStream ssResponse(SER_NETWORK, pfrom.GetCommonVersion(), request, body);
+            connman.PushMessage(&pfrom, CNetMsgMaker(pfrom.GetCommonVersion()).Make(NetMsgType::QDATA, ssResponse));
             return ret;
         };
 
@@ -715,7 +715,7 @@ PeerMsgRet CQuorumManager::ProcessMessage(CNode& pfrom, const std::string& msg_t
             return sendQDATA(CQuorumDataRequest::Errors::QUORUM_NOT_FOUND, request_limit_exceeded);
         }
 
-        CDataStream ssResponseData(SER_NETWORK, pfrom.GetSendVersion());
+        CDataStream ssResponseData(SER_NETWORK, pfrom.GetCommonVersion());
 
         // Check if request wants QUORUM_VERIFICATION_VECTOR data
         if (request.GetDataMask() & CQuorumDataRequest::QUORUM_VERIFICATION_VECTOR) {

src/llmq/signing_shares.cpp

@@ -1118,7 +1118,7 @@ bool CSigSharesManager::SendMessages()
     bool didSend = false;
 
     for (auto& pnode : vNodesCopy) {
-        CNetMsgMaker msgMaker(pnode->GetSendVersion());
+        CNetMsgMaker msgMaker(pnode->GetCommonVersion());
 
         if (const auto it1 = sigSessionAnnouncements.find(pnode->GetId()); it1 != sigSessionAnnouncements.end()) {
             std::vector<CSigSesAnn> msgs;

src/masternode/sync.cpp

@@ -152,7 +152,7 @@ void CMasternodeSync::ProcessTick()
 
     for (auto& pnode : vNodesCopy)
     {
-        CNetMsgMaker msgMaker(pnode->GetSendVersion());
+        CNetMsgMaker msgMaker(pnode->GetCommonVersion());
 
         // Don't try to sync any data from outbound non-relay "masternode" connections.
         // Inbound connection this early is most likely a "masternode" connection
@@ -301,7 +301,7 @@ void CMasternodeSync::ProcessTick()
 
 void CMasternodeSync::SendGovernanceSyncRequest(CNode* pnode) const
 {
-    CNetMsgMaker msgMaker(pnode->GetSendVersion());
+    CNetMsgMaker msgMaker(pnode->GetCommonVersion());
 
     CBloomFilter filter;
 

src/net.cpp

@@ -753,32 +753,6 @@ bool CNode::ReceiveMsgBytes(Span<const uint8_t> msg_bytes, bool& complete)
     return true;
 }
 
-void CNode::SetSendVersion(int nVersionIn)
-{
-    // Send version may only be changed in the version message, and
-    // only one version message is allowed per session. We can therefore
-    // treat this value as const and even atomic as long as it's only used
-    // once a version message has been successfully processed. Any attempt to
-    // set this twice is an error.
-    if (nSendVersion != 0) {
-        error("Send version already set for node: %i. Refusing to change from %i to %i", id, nSendVersion, nVersionIn);
-    } else {
-        nSendVersion = nVersionIn;
-    }
-}
-
-int CNode::GetSendVersion() const
-{
-    // The send version should always be explicitly set to
-    // INIT_PROTO_VERSION rather than using this value until SetSendVersion
-    // has been called.
-    if (nSendVersion == 0) {
-        error("Requesting unset send version for node: %i. Using %i", id, INIT_PROTO_VERSION);
-        return INIT_PROTO_VERSION;
-    }
-    return nSendVersion;
-}
-
 int V1TransportDeserializer::readHeader(Span<const uint8_t> msg_bytes)
 {
     // copy data to temporary parsing buffer
@@ -2364,18 +2338,23 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
 
         ConnectionType conn_type = ConnectionType::OUTBOUND_FULL_RELAY;
         int64_t nTime = GetTimeMicros();
+        bool anchor = false;
         bool fFeeler = false;
 
         // Determine what type of connection to open. Opening
-        // OUTBOUND_FULL_RELAY connections gets the highest priority until we
+        // BLOCK_RELAY connections to addresses from anchors.dat gets the highest
+        // priority. Then we open OUTBOUND_FULL_RELAY priority until we
         // meet our full-relay capacity. Then we open BLOCK_RELAY connection
         // until we hit our block-relay-only peer limit.
         // GetTryNewOutboundPeer() gets set when a stale tip is detected, so we
         // try opening an additional OUTBOUND_FULL_RELAY connection. If none of
         // these conditions are met, check the nNextFeeler timer to decide if
         // we should open a FEELER.
 
-        if (nOutboundFullRelay < m_max_outbound_full_relay) {
+        if (!m_anchors.empty() && (nOutboundBlockRelay < m_max_outbound_block_relay)) {
+            conn_type = ConnectionType::BLOCK_RELAY;
+            anchor = true;
+        } else if (nOutboundFullRelay < m_max_outbound_full_relay) {
             // OUTBOUND_FULL_RELAY
         } else if (nOutboundBlockRelay < m_max_outbound_block_relay) {
             conn_type = ConnectionType::BLOCK_RELAY;
@@ -2398,6 +2377,17 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
         int nTries = 0;
         while (!interruptNet)
         {
+            if (anchor && !m_anchors.empty()) {
+                const CAddress addr = m_anchors.back();
+                m_anchors.pop_back();
+                if (!addr.IsValid() || IsLocal(addr) || !IsReachable(addr) ||
+                    !HasAllDesirableServiceFlags(addr.nServices) ||
+                    setConnected.count(addr.GetGroup(addrman.m_asmap))) continue;
+                addrConnect = addr;
+                LogPrint(BCLog::NET, "Trying to make an anchor connection to %s\n", addrConnect.ToString());
+                break;
+            }
+
             // If we didn't find an appropriate destination after trying 100 addresses fetched from addrman,
             // stop this loop, and let the outer loop run again (which sleeps, adds seed nodes, recalculates
             // already-connected network ranges, ...) before trying new addrman addresses.
@@ -3601,7 +3591,7 @@ void CConnman::SetMasternodeQuorumRelayMembers(Consensus::LLMQType llmqType, con
             // Otherwise the peer would only announce/send messages resulting from QRECSIG,
             // e.g. InstantSend locks or ChainLocks. SPV and regular full nodes should not send
             // this message as they are usually only interested in the higher level messages.
-            const CNetMsgMaker msgMaker(pnode->GetSendVersion());
+            const CNetMsgMaker msgMaker(pnode->GetCommonVersion());
             PushMessage(pnode, msgMaker.Make(NetMsgType::QSENDRECSIGS, true));
             pnode->m_masternode_iqr_connection = true;
         }

src/net.h

@@ -134,7 +134,10 @@ struct CSerializedNetMsg
 
 /** Different types of connections to a peer. This enum encapsulates the
  * information we have available at the time of opening or accepting the
- * connection. Aside from INBOUND, all types are initiated by us. */
+ * connection. Aside from INBOUND, all types are initiated by us.
+ *
+ * If adding or removing types, please update CONNECTION_TYPE_DOC in
+ * src/rpc/net.cpp. */
 enum class ConnectionType {
     /**
      * Inbound connections are those initiated by a peer. This is the only
@@ -182,7 +185,9 @@ enum class ConnectionType {
      * attacks. By not relaying transactions or addresses, these connections
      * are harder to detect by a third party, thus helping obfuscate the
      * network topology. We automatically attempt to open
-     * MAX_BLOCK_RELAY_ONLY_CONNECTIONS using addresses from our AddrMan.
+     * MAX_BLOCK_RELAY_ONLY_ANCHORS using addresses from our anchors.dat. Then
+     * addresses from our AddrMan if MAX_BLOCK_RELAY_ONLY_CONNECTIONS
+     * isn't reached yet.
      */
     BLOCK_RELAY,
 
@@ -195,15 +200,6 @@ enum class ConnectionType {
     ADDR_FETCH,
 };
 
-const std::vector<std::string> CONNECTION_TYPE_DOC{
-    "outbound-full-relay (default automatic connections)",
-    "block-relay-only (does not relay transactions or addresses)",
-    "inbound (initiated by the peer)",
-    "manual (added via addnode RPC or -addnode/-connect configuration options)",
-    "addr-fetch (short-lived automatic connection for soliciting addresses)",
-    "feeler (short-lived automatic connection for testing addresses)"};
-
-
 class NetEventsInterface;
 class CConnman
 {
@@ -1129,7 +1125,6 @@ class CNode
     RecursiveMutex cs_sendProcessing;
 
     uint64_t nRecvBytes GUARDED_BY(cs_vRecv){0};
-    std::atomic<int> nRecvVersion{INIT_PROTO_VERSION};
 
     std::atomic<int64_t> nLastSend{0};
     std::atomic<int64_t> nLastRecv{0};
@@ -1358,6 +1353,7 @@ class CNode
     const NodeId id;
     const uint64_t nLocalHostNonce;
     const ConnectionType m_conn_type;
+    std::atomic<int> m_greatest_common_version{INIT_PROTO_VERSION};
 
     //! Services offered to this peer.
     //!
@@ -1376,7 +1372,6 @@ class CNode
     //! service advertisements.
     const ServiceFlags nLocalServices;
 
-    int nSendVersion {0};
     std::list<CNetMessage> vRecvMsg;  // Used only by SocketHandler thread
 
     mutable RecursiveMutex cs_addrName;
@@ -1423,16 +1418,14 @@ class CNode
      */
     bool ReceiveMsgBytes(Span<const uint8_t> msg_bytes, bool& complete);
 
-    void SetRecvVersion(int nVersionIn)
+    void SetCommonVersion(int greatest_common_version)
     {
-        nRecvVersion = nVersionIn;
+        m_greatest_common_version = greatest_common_version;
     }
-    int GetRecvVersion() const
+    int GetCommonVersion() const
     {
-        return nRecvVersion;
+        return m_greatest_common_version;
     }
-    void SetSendVersion(int nVersionIn);
-    int GetSendVersion() const;
 
     CService GetAddrLocal() const;
     //! May not be called more than once