add der_sequence_shrink()

in case you want to keep a sequence over a longer time, but you don't
need all the raw constructed, set or sequence data

src/headers/tomcrypt_pk.h

@@ -540,6 +540,7 @@ int der_decode_sequence_multi(const unsigned char *in, unsigned long inlen, ...)
 int  der_decode_sequence_flexi(const unsigned char *in, unsigned long *inlen, ltc_asn1_list **out);
 #define der_free_sequence_flexi         der_sequence_free
 void der_sequence_free(ltc_asn1_list *in);
+void der_sequence_shrink(ltc_asn1_list *in);
 
 /* BOOLEAN */
 int der_length_boolean(unsigned long *outlen);

src/pk/asn1/der/sequence/der_sequence_shrink.c

@@ -0,0 +1,52 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
+ */
+#include "tomcrypt.h"
+
+/**
+  @file der_sequence_shrink.c
+  Free memory allocated for CONSTRUCTED, SET or SEQUENCE elements by der_decode_sequence_flexi(), Steffen Jaeckel
+*/
+
+#ifdef LTC_DER
+
+/**
+  Free memory allocated for CONSTRUCTED,
+  SET or SEQUENCE elements by der_decode_sequence_flexi()
+  @param in     The list to shrink
+*/
+void der_sequence_shrink(ltc_asn1_list *in)
+{
+   if (!in) return;
+
+   /* now walk the list and free stuff */
+   while (in != NULL) {
+      /* is there a child? */
+      if (in->child) {
+         der_sequence_shrink(in->child);
+      }
+
+      switch (in->type) {
+         case LTC_ASN1_CONSTRUCTED:
+         case LTC_ASN1_SET:
+         case LTC_ASN1_SEQUENCE : if (in->data != NULL) { XFREE(in->data); in->data = NULL; } break;
+         default: break;
+      }
+
+      /* move to next and free current */
+      in = in->next;
+   }
+}
+
+#endif
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */