1 files changed, 82 insertions, 0 deletions
diff --git a/src/index.go b/src/index.go
new file mode 100644
index 0000000..83a7e29
--- /dev/null
+++ b/src/index.go
@@ -0,0 +1,82 @@
+package main
+
+import (
+	"crypto/rand"
+	"sync"
+)
+
+/* Index=0 is reserved for unset indecies
+ *
+ */
+
+type IndexTable struct {
+	mutex      sync.RWMutex
+	keypairs   map[uint32]*KeyPair
+	handshakes map[uint32]*Handshake
+}
+
+func randUint32() (uint32, error) {
+	var buff [4]byte
+	_, err := rand.Read(buff[:])
+	id := uint32(buff[0])
+	id <<= 8
+	id |= uint32(buff[1])
+	id <<= 8
+	id |= uint32(buff[2])
+	id <<= 8
+	id |= uint32(buff[3])
+	return id, err
+}
+
+func (table *IndexTable) Init() {
+	table.mutex.Lock()
+	defer table.mutex.Unlock()
+	table.keypairs = make(map[uint32]*KeyPair)
+	table.handshakes = make(map[uint32]*Handshake)
+}
+
+func (table *IndexTable) NewIndex(handshake *Handshake) (uint32, error) {
+	table.mutex.Lock()
+	defer table.mutex.Unlock()
+	for {
+		// generate random index
+
+		id, err := randUint32()
+		if err != nil {
+			return id, err
+		}
+		if id == 0 {
+			continue
+		}
+
+		// check if index used
+
+		_, ok := table.keypairs[id]
+		if ok {
+			continue
+		}
+		_, ok = table.handshakes[id]
+		if ok {
+			continue
+		}
+
+		// update the index
+
+		delete(table.handshakes, handshake.localIndex)
+		handshake.localIndex = id
+		table.handshakes[id] = handshake
+		return id, nil
+	}
+}
+
+func (table *IndexTable) LookupKeyPair(id uint32) *KeyPair {
+	table.mutex.RLock()
+	defer table.mutex.RUnlock()
+	return table.keypairs[id]
+}
+
+func (table *IndexTable) LookupHandshake(id uint32) *Handshake {
+	table.mutex.RLock()
+	defer table.mutex.RUnlock()
+	return table.handshakes[id]
+}