1 files changed, 79 insertions, 0 deletions
diff --git a/src/gns/gns_common.c b/src/gns/gns_common.c
new file mode 100644
index 0000000..88b365d
--- /dev/null
+++ b/src/gns/gns_common.c
@@ -0,0 +1,79 @@
+/*
+     This file is part of GNUnet.
+     (C) 2012 Christian Grothoff (and other contributing authors)
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+/**
+ *
+ * @file gns/gns_common.c
+ * @brief helper functions shared between GNS service and block plugin
+ * @author Martin Schanzenbach
+ */
+#include "platform.h"
+#include "gns_common.h"
+
+
+/**
+ * Compute the DHT key for a name in a zone.
+ * DHT key is H(name) xor H(pubkey).
+ *
+ * @param name name of the record
+ * @param zone GADS zone
+ * @param key where to store the DHT key for records under this name in the given zone
+ */
+void 
+GNUNET_GNS_get_key_for_record (const char *name,
+			       const struct GNUNET_CRYPTO_ShortHashCode *zone,
+			       struct GNUNET_HashCode *key)
+{
+  struct GNUNET_CRYPTO_ShortHashCode name_hash;
+  struct GNUNET_HashCode name_hash_double;
+  struct GNUNET_HashCode zone_hash_double;
+
+  GNUNET_CRYPTO_short_hash (name,
+			    strlen (name),
+			    &name_hash);
+  GNUNET_CRYPTO_short_hash_double (&name_hash, &name_hash_double);
+  GNUNET_CRYPTO_short_hash_double (zone, &zone_hash_double);
+  GNUNET_CRYPTO_hash_xor(&name_hash_double, &zone_hash_double, key);
+}
+
+
+/**
+ * Compute the zone identifier from a given DHT key and record name.
+ *
+ * @param name name of the record
+ * @param key DHT key of the record
+ * @param zone set to the corresponding zone hash
+ */
+void 
+GNUNET_GNS_get_zone_from_key (const char *name,
+			      const struct GNUNET_HashCode *key,			       
+			      struct GNUNET_CRYPTO_ShortHashCode *zone)
+{
+  struct GNUNET_CRYPTO_ShortHashCode name_hash;
+  struct GNUNET_HashCode name_hash_double;
+  struct GNUNET_HashCode zone_hash_double;
+
+  GNUNET_CRYPTO_short_hash(name, strlen(name), &name_hash);
+  GNUNET_CRYPTO_short_hash_double(&name_hash, &name_hash_double);
+  GNUNET_CRYPTO_hash_xor(key, &name_hash_double, &zone_hash_double);
+  GNUNET_CRYPTO_short_hash_from_truncation (&zone_hash_double, zone);
+}			       
+
+
+/* end of gns_common.c */