Simplify DH_check_params a bit.

It makes no sense to allocate an entire BN_CTX if we only use it to
get a single BIGNUM, from which we subtract 1 to compare it to g.
We can just use a plain BIGNUM and delete a bunch of lines.

ok inoguchi jsing

diff --git a/lib/libcrypto/dh/dh_check.c b/lib/libcrypto/dh/dh_check.c
index 7b9fcbd..a3d2c98 100644 (file)
--- a/lib/libcrypto/dh/dh_check.c
+++ b/lib/libcrypto/dh/dh_check.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dh_check.c,v 1.21 2021/11/29 20:02:14 tb Exp $ */
+/* $OpenBSD: dh_check.c,v 1.22 2021/12/05 13:45:26 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -68,18 +68,11 @@
 int
 DH_check_params(const DH *dh, int *flags)
 {
-       BN_CTX *ctx = NULL;
-       BIGNUM *max_g;
+       BIGNUM *max_g = NULL;
        int ok = 0;
 
        *flags = 0;
 
-       if ((ctx = BN_CTX_new()) == NULL)
-               goto err;
-       BN_CTX_start(ctx);
-       if ((max_g = BN_CTX_get(ctx)) == NULL)
-               goto err;
-
        if (!BN_is_odd(dh->p))
                *flags |= DH_CHECK_P_NOT_PRIME;
 
@@ -90,7 +83,7 @@ DH_check_params(const DH *dh, int *flags)
        if (BN_cmp(dh->g, BN_value_one()) <= 0)
                *flags |= DH_NOT_SUITABLE_GENERATOR;
        /* max_g = p - 1 */
-       if (BN_copy(max_g, dh->p) == NULL)
+       if ((max_g = BN_dup(dh->p)) == NULL)
                goto err;
        if (!BN_sub_word(max_g, 1))
                goto err;
@@ -101,8 +94,7 @@ DH_check_params(const DH *dh, int *flags)
        ok = 1;
 
  err:
-       BN_CTX_end(ctx);
-       BN_CTX_free(ctx);
+       BN_free(max_g);
 
        return ok;
 }