Incremental cleanups to bn_lib.c.

- Add missing bn_check_top() calls and relocate some others
- Use BN_is_zero() where appropriate
- Remove assert()s that bn_check_top() is already covering
- Simplify the code in places (esp. bn_expand2())
- Only keep ambiguous zero handling if BN_STRICT isn't defined
- Remove some white-space and make some other aesthetic tweaks

1 files changed, 38 insertions, 48 deletions

diff --git a/crypto/bn/bn_lib.c b/crypto/bn/bn_lib.c
index 3bc67f9de2..d29a7cc8df 100644
--- a/crypto/bn/bn_lib.c
+++ b/crypto/bn/bn_lib.c
@@ -244,16 +244,11 @@ int BN_num_bits_word(BN_ULONG l)
 
 int BN_num_bits(const BIGNUM *a)
 	{
-	BN_ULONG l;
-	int i;
-
+	int i = a->top - 1;
 	bn_check_top(a);
 
-	if (a->top == 0) return(0);
-	l=a->d[a->top-1];
-	assert(l != 0);
-	i=(a->top-1)*BN_BITS2;
-	return(i+BN_num_bits_word(l));
+	if (BN_is_zero(a)) return 0;
+	return ((i*BN_BITS2) + BN_num_bits_word(a->d[i]));
 	}
 
 void BN_clear_free(BIGNUM *a)
@@ -261,6 +256,7 @@ void BN_clear_free(BIGNUM *a)
 	int i;
 
 	if (a == NULL) return;
+	bn_check_top(a);
 	if (a->d != NULL)
 		{
 		OPENSSL_cleanse(a->d,a->dmax*sizeof(a->d[0]));
@@ -276,6 +272,7 @@ void BN_clear_free(BIGNUM *a)
 void BN_free(BIGNUM *a)
 	{
 	if (a == NULL) return;
+	bn_check_top(a);
 	if ((a->d != NULL) && !(BN_get_flags(a,BN_FLG_STATIC_DATA)))
 		OPENSSL_free(a->d);
 	if (a->flags & BN_FLG_MALLOCED)
@@ -321,13 +318,13 @@ static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
 	const BN_ULONG *B;
 	int i;
 
+	bn_check_top(b);
+
 	if (words > (INT_MAX/(4*BN_BITS2)))
 		{
 		BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_BIGNUM_TOO_LONG);
 		return NULL;
 		}
-
-	bn_check_top(b);	
 	if (BN_get_flags(b,BN_FLG_STATIC_DATA))
 		{
 		BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
@@ -394,12 +391,14 @@ BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
 	{
 	BIGNUM *r = NULL;
 
+	bn_check_top(b);
+
 	/* This function does not work if
 	 *      words <= b->dmax && top < words
 	 * because BN_dup() does not preserve 'dmax'!
 	 * (But bn_dup_expand() is not used anywhere yet.)
 	 */
-	
+
 	if (words > b->dmax)
 		{
 		BN_ULONG *a = bn_expand_internal(b, words);
@@ -443,23 +442,19 @@ BIGNUM *bn_expand2(BIGNUM *b, int words)
 	BN_ULONG *A;
 	int i;
 
+	bn_check_top(b);
+
 	if (words > b->dmax)
 		{
 		BN_ULONG *a = bn_expand_internal(b, words);
-
-		if (a)
-			{
-			if (b->d)
-				OPENSSL_free(b->d);
-			b->d=a;
-			b->dmax=words;
-			}
-		else
-			b = NULL;
+		if(!a) return NULL;
+		if(b->d) OPENSSL_free(b->d);
+		b->d=a;
+		b->dmax=words;
 		}
-	
+
 	/* NB: bn_wexpand() calls this only if the BIGNUM really has to grow */
-	if ((b != NULL) && (b->top < b->dmax))
+	if (b->top < b->dmax)
 		{
 		A = &(b->d[b->top]);
 		for (i=(b->dmax - b->top)>>3; i>0; i--,A+=8)
@@ -471,26 +466,26 @@ BIGNUM *bn_expand2(BIGNUM *b, int words)
 			A[0]=0;
 		assert(A == &(b->d[b->dmax]));
 		}
-	else if(b) bn_check_top(b);
+	bn_check_top(b);
 	return b;
 	}
 
 BIGNUM *BN_dup(const BIGNUM *a)
 	{
-	BIGNUM *r, *t;
+	BIGNUM *t;
 
 	if (a == NULL) return NULL;
-
 	bn_check_top(a);
 
 	t = BN_new();
-	if (t == NULL) return(NULL);
-	r = BN_copy(t, a);
-	/* now  r == t || r == NULL */
-	if (r == NULL)
+	if (t == NULL) return NULL;
+	if(!BN_copy(t, a))
+		{
 		BN_free(t);
-	bn_check_top(r);
-	return r;
+		return NULL;
+		}
+	bn_check_top(t);
+	return t;
 	}
 
 BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
@@ -524,10 +519,11 @@ BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
 	memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
 #endif
 
-/*	memset(&(a->d[b->top]),0,sizeof(a->d[0])*(a->max-b->top));*/
 	a->top=b->top;
+#ifndef BN_STRICT
 	if ((a->top == 0) && (a->d != NULL))
 		a->d[0]=0;
+#endif
 	a->neg=b->neg;
 	bn_check_top(a);
 	return(a);
@@ -540,18 +536,15 @@ BIGNUM *BN_ncopy(BIGNUM *a, const BIGNUM *b, size_t n)
 	const BN_ULONG *B;
 
 	bn_check_top(b);
-
 	if (a == b)
 		return a;
 
 	min = (b->top < (int)n)? b->top: (int)n;
-
 	if (!min)
 		{
 		BN_zero(a);
 		return a;
 		}
-
 	if (bn_wexpand(a, min) == NULL)
 		return NULL;
 
@@ -571,11 +564,8 @@ BIGNUM *BN_ncopy(BIGNUM *a, const BIGNUM *b, size_t n)
 		case 0: ;
 		}
 	a->top = min;
-
 	a->neg = b->neg;
 	bn_correct_top(a);
-
-	bn_check_top(a);
 	return(a);
 	}
 
@@ -612,7 +602,6 @@ void BN_swap(BIGNUM *a, BIGNUM *b)
 	bn_check_top(b);
 	}
 
-
 void BN_clear(BIGNUM *a)
 	{
 	bn_check_top(a);
@@ -743,7 +732,7 @@ int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
 		t1= ap[i];
 		t2= bp[i];
 		if (t1 != t2)
-			return(t1 > t2?1:-1);
+			return((t1 > t2) ? 1 : -1);
 		}
 	return(0);
 	}
@@ -815,8 +804,8 @@ int BN_clear_bit(BIGNUM *a, int n)
 	{
 	int i,j;
 
-	if (n < 0)
-		return 0;
+	bn_check_top(a);
+	if (n < 0) return 0;
 
 	i=n/BN_BITS2;
 	j=n%BN_BITS2;
@@ -831,10 +820,11 @@ int BN_is_bit_set(const BIGNUM *a, int n)
 	{
 	int i,j;
 
-	if (n < 0) return(0);
+	bn_check_top(a);
+	if (n < 0) return 0;
 	i=n/BN_BITS2;
 	j=n%BN_BITS2;
-	if (a->top <= i) return(0);
+	if (a->top <= i) return 0;
 	return((a->d[i]&(((BN_ULONG)1)<<j))?1:0);
 	}
 
@@ -842,12 +832,12 @@ int BN_mask_bits(BIGNUM *a, int n)
 	{
 	int b,w;
 
-	if (n < 0)
-		return 0;
+	bn_check_top(a);
+	if (n < 0) return 0;
 
 	w=n/BN_BITS2;
 	b=n%BN_BITS2;
-	if (w >= a->top) return(0);
+	if (w >= a->top) return 0;
 	if (b == 0)
 		a->top=w;
 	else