move udpproxy files into repo root

sessioncache.go

@@ -0,0 +1,41 @@
+package udpproxy
+
+import "sync"
+
+// sessionCache tracks connection sessions
+type sessionCache struct {
+	mu   sync.RWMutex
+	data map[string]*session
+}
+
+// newSessionCache creates a usable sessionCache.
+func newSessionCache() sessionCache {
+	return sessionCache{
+		data: make(map[string]*session),
+	}
+}
+
+// read returns the associated session for an addr
+func (sc *sessionCache) read(addr string) (*session, bool) {
+	sc.mu.RLock()
+	defer sc.mu.RUnlock()
+
+	v, ok := sc.data[addr]
+	return v, ok
+}
+
+// insert adds a session for a given addr.
+func (sc *sessionCache) insert(addr string, session *session) {
+	sc.mu.Lock()
+	defer sc.mu.Unlock()
+
+	sc.data[addr] = session
+}
+
+// delete removes the session for the given addr.
+func (sc *sessionCache) delete(addr string) {
+	sc.mu.Lock()
+	defer sc.mu.Unlock()
+
+	delete(sc.data, addr)
+}