diff --git a/db.h b/db.h
new file mode 100644
index 0000000..fd4c149
--- /dev/null
+++ b/db.h
@@ -0,0 +1,44 @@
+#include <stdint.h>
+
+#include <pair>
+#include <set>
+#include <map>
+#include <vector>
+#include <deque>
+
+#include "netbase.h"
+#include "protocol.h"
+#include "util.h"
+
+class CAddrInfo {
+private:
+  CIP ip;
+  uint64_t services;
+  uint32_t lastTry;
+  uint32_t ourLastTry;
+  double reliabity;
+  double weight;
+}
+
+class CAddrDb {
+private:
+  CCriticalSection cs;
+  int nId; // number of address id's
+  map<int, CAddrInfo> idToInfo; // map address id to address info
+  map<CIP, int> ipToId; // map ip to id
+  deque<int> ourId; // sequence of tracked nodes, in order we have tried connecting to them
+  set<int> unkId; // set of nodes not yet tried
+  set<int> goodId; // set of good nodes 
+  map<CIP, pair<uint32_t, uint32_t> > banned; // nodes that are banned, with their from/to ban time
+  
+public:
+  void Add(const CAddress &addr);
+  void Add(const vector<CAddress> &vAddr);
+  void Good(const CIP &addr);
+  void Bad(const CIP &addr, int fail);
+  CIP Get();
+}
+
+extern "C" {
+  int GetIPv4Address(struct in_addr *addr, int max);
+}
diff --git a/util.h b/util.h
index 6bdd2e1..6da6331 100644
--- a/util.h
+++ b/util.h
@@ -1,6 +1,8 @@
 #ifndef _UTIL_H_
 #define _UTIL_H_ 1
 
+#include <pthread.h>
+
 #define loop                for (;;)
 #define BEGIN(a)            ((char*)&(a))
 #define END(a)              ((char*)&((&(a))[1]))
@@ -34,4 +36,31 @@ inline int myclosesocket(SOCKET& hSocket)
 }
 #define closesocket(s)      myclosesocket(s)
 
+
+// Wrapper to automatically initialize mutex
+class CCriticalSection
+{
+protected:
+    pthread_mutex_t mutex;
+public:
+    explicit CCriticalSection() { pthread_mutex_init(&mutex, NULL); }
+    ~CCriticalSection() { pthread_mutex_destroy(&mutex); }
+    void Enter() { pthread_mutex_lock(&mutex); }
+    void Leave() { pthread_mutex_unlock(&mutex); }
+};
+
+// Automatically leave critical section when leaving block, needed for exception safety
+class CCriticalBlock
+{
+protected:
+    CCriticalSection* pcs;
+public:
+    CCriticalBlock(CCriticalSection& cs) : pcs(&cs) { pcs->Enter(); }
+    operator bool() const { return true; }
+    ~CCriticalBlock() { pcs->Leave(); }
+};
+
+#define CRITICAL_BLOCK(cs)     \
+    if (CCriticalBlock criticalblock = CCriticalBlock(cs))
+
 #endif