net: disable v1 connections, reconnections on clearnet

if `-v2onlyclearnet` is turned on,
- v1 addresses from addrman aren't selected and manual connections
aren't attempted for outbound connections if it's from IPV4/IPV6
networks.
- v1 downgrade mechainm is not attempted if v2 connection wasn't
successful

Author: stratospher

src/net.cpp

@@ -1892,7 +1892,7 @@ void CConnman::DisconnectNodes()
                 // Add to reconnection list if appropriate. We don't reconnect right here, because
                 // the creation of a connection is a blocking operation (up to several seconds),
                 // and we don't want to hold up the socket handler thread for that long.
-                if (pnode->m_transport->ShouldReconnectV1()) {
+                if (pnode->m_transport->ShouldReconnectV1() && !DisableV1OnClearnet(pnode->addr.GetNetClass())) {
                     reconnections_to_add.push_back({
                         .addr_connect = pnode->addr,
                         .grant = std::move(pnode->grantOutbound),
@@ -2766,6 +2766,11 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect, Spa
                 continue;
             }
 
+            bool use_v2transport(addr.nServices & GetLocalServices() & NODE_P2P_V2);
+            if (DisableV1OnClearnet(addr.GetNetClass()) && !use_v2transport) {
+                continue;
+            }
+
             // only consider very recently tried nodes after 30 failed attempts
             if (current_time - addr_last_try < 10min && nTries < 30) {
                 continue;
@@ -2948,6 +2953,19 @@ void CConnman::OpenNetworkConnection(const CAddress& addrConnect, bool fCountFai
     } else if (FindNode(std::string(pszDest)))
         return;
 
+    enum Network netclass;
+    if (pszDest) {
+        std::string host;
+        uint16_t port;
+        SplitHostPort(std::string(pszDest), port, host);
+        netclass = LookupHost(host, false).value().GetNetClass();
+    } else {
+        netclass = addrConnect.GetNetClass();
+    }
+    if (DisableV1OnClearnet(netclass) && !use_v2transport) {
+        return;
+    }
+
     CNode* pnode = ConnectNode(addrConnect, pszDest, fCountFailure, conn_type, use_v2transport);
 
     if (!pnode)

src/net_processing.cpp

@@ -3784,6 +3784,12 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
             return;
         }
 
+        const bool is_v1transport = pfrom.m_transport->GetInfo().transport_type == TransportProtocolType::V1;
+        if (pfrom.IsInboundConn() && is_v1transport && m_connman.DisableV1OnClearnet(pfrom.ConnectedThroughNetwork())){
+            pfrom.fDisconnect = true;
+            return;
+        }
+
         if (pfrom.IsInboundConn() && addrMe.IsRoutable())
         {
             SeenLocal(addrMe);