1 files changed, 65 insertions, 0 deletions
diff --git a/src/netbase.h b/src/netbase.h
index 1da4f5c51d..8b7da4109f 100644
--- a/src/netbase.h
+++ b/src/netbase.h
@@ -19,6 +19,7 @@
 #include <stdint.h>
 #include <string>
 #include <type_traits>
+#include <unordered_set>
 #include <vector>
 
 extern int nConnectTimeout;
@@ -65,6 +66,61 @@ struct ProxyCredentials
 };
 
 /**
+ * List of reachable networks. Everything is reachable by default.
+ */
+class ReachableNets {
+public:
+    void Add(Network net) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex)
+    {
+        AssertLockNotHeld(m_mutex);
+        LOCK(m_mutex);
+        m_reachable.insert(net);
+    }
+
+    void Remove(Network net) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex)
+    {
+        AssertLockNotHeld(m_mutex);
+        LOCK(m_mutex);
+        m_reachable.erase(net);
+    }
+
+    void RemoveAll() EXCLUSIVE_LOCKS_REQUIRED(!m_mutex)
+    {
+        AssertLockNotHeld(m_mutex);
+        LOCK(m_mutex);
+        m_reachable.clear();
+    }
+
+    [[nodiscard]] bool Contains(Network net) const EXCLUSIVE_LOCKS_REQUIRED(!m_mutex)
+    {
+        AssertLockNotHeld(m_mutex);
+        LOCK(m_mutex);
+        return m_reachable.count(net) > 0;
+    }
+
+    [[nodiscard]] bool Contains(const CNetAddr& addr) const EXCLUSIVE_LOCKS_REQUIRED(!m_mutex)
+    {
+        AssertLockNotHeld(m_mutex);
+        return Contains(addr.GetNetwork());
+    }
+
+private:
+    mutable Mutex m_mutex;
+
+    std::unordered_set<Network> m_reachable GUARDED_BY(m_mutex){
+        NET_UNROUTABLE,
+        NET_IPV4,
+        NET_IPV6,
+        NET_ONION,
+        NET_I2P,
+        NET_CJDNS,
+        NET_INTERNAL
+    };
+};
+
+extern ReachableNets g_reachable_nets;
+
+/**
  * Wrapper for getaddrinfo(3). Do not use directly: call Lookup/LookupHost/LookupNumeric/LookupSubNet.
  */
 std::vector<CNetAddr> WrappedGetAddrInfo(const std::string& name, bool allow_lookup);
@@ -251,4 +307,13 @@ bool Socks5(const std::string& strDest, uint16_t port, const ProxyCredentials* a
  */
 bool IsBadPort(uint16_t port);
 
+/**
+ * If an IPv6 address belongs to the address range used by the CJDNS network and
+ * the CJDNS network is reachable (-cjdnsreachable config is set), then change
+ * the type from NET_IPV6 to NET_CJDNS.
+ * @param[in] service Address to potentially convert.
+ * @return a copy of `service` either unmodified or changed to CJDNS.
+ */
+CService MaybeFlipIPv6toCJDNS(const CService& service);
+
 #endif // BITCOIN_NETBASE_H