Added a basic TUN, testing the implementation.

include/columnlynx/common/net/session_registry.hpp

@@ -21,6 +21,9 @@ namespace ColumnLynx::Net {
         std::atomic<uint64_t> sendCounter{0};
         std::chrono::steady_clock::time_point created = std::chrono::steady_clock::now();
         std::chrono::steady_clock::time_point expires{};
+        uint32_t clientTunIP;
+        uint32_t serverTunIP;
+        uint64_t sessionID;
         Nonce base_nonce{};
 
         ~SessionState() { sodium_memzero(aesKey.data(), aesKey.size()); }
@@ -29,7 +32,7 @@ namespace ColumnLynx::Net {
         SessionState(SessionState&&) = default;
         SessionState& operator=(SessionState&&) = default;
 
-        explicit SessionState(const SymmetricKey& k, std::chrono::seconds ttl = std::chrono::hours(24)) : aesKey(k) {
+        explicit SessionState(const SymmetricKey& k, std::chrono::seconds ttl = std::chrono::hours(24), uint32_t clientIP = 0, uint32_t serverIP = 0, uint64_t id = 0) : aesKey(k), clientTunIP(clientIP), serverTunIP(serverIP), sessionID(id) {
             expires = created + ttl;
         }
 
@@ -46,6 +49,7 @@ namespace ColumnLynx::Net {
             void put(uint64_t sessionID, std::shared_ptr<SessionState> state) {
                 std::unique_lock lock(mMutex);
                 mSessions[sessionID] = std::move(state);
+                mIPSessions[mSessions[sessionID]->clientTunIP] = mSessions[sessionID];
             }
 
             // Lookup
@@ -55,6 +59,12 @@ namespace ColumnLynx::Net {
                 return (it == mSessions.end()) ? nullptr : it->second;
             }
 
+            std::shared_ptr<const SessionState> getByIP(uint32_t ip) const {
+                std::shared_lock lock(mMutex);
+                auto it = mIPSessions.find(ip);
+                return (it == mIPSessions.end()) ? nullptr : it->second;
+            }
+
             std::unordered_map<uint64_t, std::shared_ptr<SessionState>> snapshot() const {
                 std::unordered_map<uint64_t, std::shared_ptr<SessionState>> snap;
                 std::shared_lock lock(mMutex);
@@ -79,10 +89,50 @@ namespace ColumnLynx::Net {
                         ++it;
                     }
                 }
+
+                for (auto it = mIPSessions.begin(); it != mIPSessions.end(); ) {
+                    if (it->second && it->second->expires <= now) {
+                        it = mIPSessions.erase(it);
+                    } else {
+                        ++it;
+                    }
+                }
+            }
+
+            int size() const {
+                std::shared_lock lock(mMutex);
+                return static_cast<int>(mSessions.size());
+            }
+
+            // IP management (simple for /24 subnet)
+
+            uint32_t getFirstAvailableIP() const {
+                std::shared_lock lock(mMutex);
+                uint32_t baseIP = 0x0A0A0002; // 10.10.0.2
+
+                // TODO: Expand to support larger subnets
+                for (uint32_t offset = 0; offset < 254; offset++) {
+                    uint32_t candidateIP = baseIP + offset;
+                    if (mSessionIPs.find(candidateIP) == mSessionIPs.end()) {
+                        return candidateIP;
+                    }                    
+                }
+            }
+
+            void lockIP(uint64_t sessionID, uint32_t ip) {
+                std::unique_lock lock(mMutex);
+                mSessionIPs[sessionID] = ip;
+            }
+
+            void deallocIP(uint64_t sessionID) {
+                std::unique_lock lock(mMutex);
+                mSessionIPs.erase(sessionID);
             }
 
         private:
             mutable std::shared_mutex mMutex;
             std::unordered_map<uint64_t, std::shared_ptr<SessionState>> mSessions;
+            std::unordered_map<uint64_t, uint32_t> mSessionIPs;
+            std::unordered_map<uint32_t, std::shared_ptr<SessionState>> mIPSessions;
     };
 }