interfaces: expose network reachability to the GUI

Node::isReachable(Network) answers whether outbound connections to a network are allowed, from g_reachable_nets: the effect of -onlynet, -onion, -noonion and the onion proxy the Tor controller configures once it has connected. The DashPay GUI needs it to choose how it connects to evonodes the way Core connects to its peers, and reading -onlynet itself would miss everything but -onlynet.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: PastaPastaPasta

src/interfaces/node.h

@@ -413,6 +413,10 @@ class Node
     //! Get proxy.
     virtual bool getProxy(Network net, Proxy& proxy_info) = 0;
 
+    //! Whether outbound connections to this network are allowed (-onlynet,
+    //! -onion, -noonion and the onion proxy the Tor controller configures).
+    virtual bool isReachable(Network net) = 0;
+
     //! Get number of connections.
     virtual size_t getNodeCount(ConnectionDirection flags) = 0;
 

src/node/interfaces.cpp

@@ -957,6 +957,7 @@ class NodeImpl : public Node
     }
     void mapPort(bool use_upnp, bool use_natpmp) override { StartMapPort(use_upnp, use_natpmp); }
     bool getProxy(Network net, Proxy& proxy_info) override { return GetProxy(net, proxy_info); }
+    bool isReachable(Network net) override { return g_reachable_nets.Contains(net); }
     size_t getNodeCount(ConnectionDirection flags) override
     {
         return m_context->connman ? m_context->connman->GetNodeCount(flags) : 0;