blanket-v2-only option

src/init.cpp

@@ -938,6 +938,13 @@ bool AppInitParameterInteraction(const ArgsManager& args)
     // Signal NODE_P2P_V2 if BIP324 v2 transport is enabled.
     if (args.GetBoolArg("-v2transport", DEFAULT_V2_TRANSPORT)) {
         nLocalServices = ServiceFlags(nLocalServices | NODE_P2P_V2);
+    } else {
+        std::optional<std::string> cmd = args.GetArg("-v2transport");
+        if (cmd.has_value() && cmd.value() == "only") {
+            nLocalServices = ServiceFlags(nLocalServices | NODE_P2P_V2);
+            g_v2_only = true;
+            LogPrintf("### BLANKET V2 ONLY OPTION SET\n");
+        }
     }
 
     // Signal NODE_COMPACT_FILTERS if peerblockfilters and basic filters index are both enabled.

src/net.cpp

@@ -1793,6 +1793,13 @@ void CConnman::CreateNodeFromAcceptedSocket(std::unique_ptr<Sock>&& sock,
     // detected, so use it whenever we signal NODE_P2P_V2.
     const bool use_v2transport(nLocalServices & NODE_P2P_V2);
 
+    if (g_v2_only && !use_v2transport) {
+        //TODO: do we really need to log? do we log connection was accepted?
+        LogPrint(BCLog::NET, "### 1. NOT V2 PEER - INBOUND CONNECTION\n");
+        LogPrint(BCLog::NET, "connection from %s dropped (v1 disabled)\n", addr.ToStringAddrPort());
+        return;
+    }
+
     CNode* pnode = new CNode(id,
                              std::move(sock),
                              addr,
@@ -1893,7 +1900,7 @@ 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 (!g_v2_only && pnode->m_transport->ShouldReconnectV1()) {
                     reconnections_to_add.push_back({
                         .addr_connect = pnode->addr,
                         .grant = std::move(pnode->grantOutbound),
@@ -2346,6 +2353,13 @@ void CConnman::ProcessAddrFetch()
     // Attempt v2 connection if we support v2 - we'll reconnect with v1 if our
     // peer doesn't support it or immediately disconnects us for another reason.
     const bool use_v2transport(GetLocalServices() & NODE_P2P_V2);
+    if (g_v2_only && !use_v2transport) {
+        //TODO: better if this can be handled in OpenNetworkConnection() itself
+        //because this is at a loss of addrfetch connection
+        // TODO: check how connections are made only if a specific service flag is advertised
+        LogPrint(BCLog::NET, "### 2. NOT V2 PEER FOR ADDR_FETCH\n");
+        return;
+    }
     CAddress addr;
     CSemaphoreGrant grant(*semOutbound, /*fTry=*/true);
     if (grant) {
@@ -2463,6 +2477,11 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
         // Attempt v2 connection if we support v2 - we'll reconnect with v1 if our
         // peer doesn't support it or immediately disconnects us for another reason.
         const bool use_v2transport(GetLocalServices() & NODE_P2P_V2);
+        if (g_v2_only && !use_v2transport) {
+            //TODO: IMP: does this break out of the next for loop too?
+            LogPrint(BCLog::NET, "### 3. NOT V2 PEER - BEFORE MANUAL (INSIDE OPENCON)\n");
+            return;
+        }
         for (int64_t nLoop = 0;; nLoop++)
         {
             for (const std::string& strAddr : connect)
@@ -2766,6 +2785,11 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
                 continue;
             }
 
+            bool use_v2transport(addr.nServices & GetLocalServices() & NODE_P2P_V2);
+            if (g_v2_only && !use_v2transport) {
+                LogPrint(BCLog::NET, "### 4.0 NOT V2 PEER (IN OPENCON) - WE TRY AGAIN FOR V2\n");
+                continue;
+            }
             addrConnect = addr;
             break;
         }
@@ -2883,6 +2907,7 @@ void CConnman::ThreadOpenAddedConnections()
             }
             tried = true;
             CAddress addr(CService(), NODE_NONE);
+            //TODO
             OpenNetworkConnection(addr, false, std::move(grant), info.m_params.m_added_node.c_str(), ConnectionType::MANUAL, info.m_params.m_use_v2transport);
             if (!interruptNet.sleep_for(std::chrono::milliseconds(500))) return;
             grant = CSemaphoreGrant(*semAddnode, /*fTry=*/true);
@@ -2916,7 +2941,12 @@ void CConnman::OpenNetworkConnection(const CAddress& addrConnect, bool fCountFai
             return;
         }
     } else if (FindNode(std::string(pszDest)))
+        return; //todo: how is it possible to hit this path
+
+    if (g_v2_only && !use_v2transport) {
+        LogPrint(BCLog::NET, "### 5. NOT V2 PEER (IN OPENNETWORKCONN())\n");
         return;
+    }
 
     CNode* pnode = ConnectNode(addrConnect, pszDest, fCountFailure, conn_type, use_v2transport);
 

src/netbase.cpp

@@ -41,6 +41,7 @@ std::chrono::milliseconds g_socks5_recv_timeout = 20s;
 CThreadInterrupt g_socks5_interrupt;
 
 ReachableNets g_reachable_nets;
+bool g_v2_only = false;
 
 std::vector<CNetAddr> WrappedGetAddrInfo(const std::string& name, bool allow_lookup)
 {

src/netbase.h

@@ -149,6 +149,7 @@ class ReachableNets {
 };
 
 extern ReachableNets g_reachable_nets;
+extern bool g_v2_only;
 
 /**
  * Wrapper for getaddrinfo(3). Do not use directly: call Lookup/LookupHost/LookupNumeric/LookupSubNet.

src/rpc/net.cpp

@@ -335,6 +335,7 @@ static RPCHelpMan addnode()
     const auto node_arg{self.Arg<std::string>("node")};
     bool node_v2transport = connman.GetLocalServices() & NODE_P2P_V2;
     bool use_v2transport = self.MaybeArg<bool>("v2transport").value_or(node_v2transport);
+    //TODO: disallow v1 if v2_only = true; (throw an error)
 
     if (use_v2transport && !node_v2transport) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Error: v2transport requested but not enabled (see -v2transport)");