add first sketch of a DB backend
diff --git a/src/db.h b/src/db.h
new file mode 100644
index 0000000..edf1655
--- /dev/null
+++ b/src/db.h
@@ -0,0 +1,23 @@
+#include <stdint.h>
+
+#define NUMBER_LENGTH 32
+
+typedef struct {
+ uint64_t imsi;
+ uint64_t tmsi;
+ char number[NUMBER_LENGTH];
+ uint16_t lac;
+} db_subscriber;
+
+int db_init();
+int db_prepare();
+int db_fini();
+
+int db_insert_imei(uint64_t imei);
+
+int db_insert_imsi(uint64_t imsi);
+int db_imsi_set_tmsi(uint64_t imsi, uint64_t tmsi);
+int db_imsi_set_lac(uint64_t imsi, uint16_t lac);
+int db_imsi_get_subscriber(uint64_t imsi, db_subscriber* subscriber);
+int db_tmsi_get_subscriber(uint64_t tmsi, db_subscriber* subscriber);
+