src/pluto/mp_defs.c

@@ -0,0 +1,70 @@
+/* some multiprecision utilities
+ * Copyright (C) 1998-2001  D. Hugh Redelmeier.
+ *
+ * This program 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 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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.
+ *
+ * RCSID $Id: mp_defs.c,v 1.1 2006/01/05 12:37:11 as Exp $
+ */
+
+#include <freeswan.h>
+
+#include "constants.h"
+#include "defs.h"
+#include "mp_defs.h"
+#include "log.h"
+
+/* Convert MP_INT to network form (binary octets, big-endian).
+ * We do the malloc; caller must eventually do free.
+ */
+chunk_t
+mpz_to_n(const MP_INT *mp, size_t bytes)
+{
+    chunk_t r;
+    MP_INT temp1, temp2;
+    int i;
+
+    r.len = bytes;
+    r.ptr = alloc_bytes(r.len, "host representation of large integer");
+
+    mpz_init(&temp1);
+    mpz_init(&temp2);
+
+    mpz_set(&temp1, mp);
+
+    for (i = r.len-1; i >= 0; i--)
+    {
+	r.ptr[i] = mpz_mdivmod_ui(&temp2, NULL, &temp1, 1 << BITS_PER_BYTE);
+	mpz_set(&temp1, &temp2);
+    }
+
+    passert(mpz_sgn(&temp1) == 0);	/* we must have done all the bits */
+    mpz_clear(&temp1);
+    mpz_clear(&temp2);
+
+    return r;
+}
+
+/* Convert network form (binary bytes, big-endian) to MP_INT.
+ * The *mp must not be previously mpz_inited.
+ */
+void
+n_to_mpz(MP_INT *mp, const u_char *nbytes, size_t nlen)
+{
+    size_t i;
+
+    mpz_init_set_ui(mp, 0);
+
+    for (i = 0; i != nlen; i++)
+    {
+	mpz_mul_ui(mp, mp, 1 << BITS_PER_BYTE);
+	mpz_add_ui(mp, mp, nbytes[i]);
+    }
+}