The previous commit to crypto/stack/*.[ch] pulled the type-safety strings

yet tighter, and also put some heat on the rest of the library by
insisting (correctly) that compare callbacks used in stacks are prototyped
with "const" parameters. This has led to a depth-first explosion of
compiler warnings in the code where 1 constification has led to 3 or 4
more. Fortunately these have all been resolved to completion and the code
seems cleaner as a result - in particular many of the _cmp() functions
should have been prototyped with "const"s, and now are. There was one
little problem however;

X509_cmp() should by rights compare "const X509 *" pointers, and it is now
declared as such. However, it's internal workings can involve
recalculating hash values and extensions if they have not already been
setup. Someone with a more intricate understanding of the flow control of
X509 might be able to tighten this up, but for now - this seemed the
obvious place to stop the "depth-first" constification of the code by
using an evil cast (they have migrated all the way here from safestack.h).

Fortunately, this is the only place in the code where this was required
to complete these type-safety changes, and it's reasonably clear and
commented, and seemed the least unacceptable of the options. Trying to
take the constification further ends up exploding out considerably, and
indeed leads directly into generalised ASN functions which are not likely
to cooperate well with this.

4 files changed, 37 insertions, 26 deletions

diff --git a/crypto/x509/x509.h b/crypto/x509/x509.h
index a0aaad8366..a5cb555589 100644
--- a/crypto/x509/x509.h
+++ b/crypto/x509/x509.h
@@ -659,11 +659,14 @@ int X509_REQ_sign(X509_REQ *x, EVP_PKEY *pkey, const EVP_MD *md);
 int X509_CRL_sign(X509_CRL *x, EVP_PKEY *pkey, const EVP_MD *md);
 int NETSCAPE_SPKI_sign(NETSCAPE_SPKI *x, EVP_PKEY *pkey, const EVP_MD *md);
 
-int X509_digest(X509 *data,const EVP_MD *type,unsigned char *md,unsigned int *len);
-int X509_CRL_digest(X509_CRL *data,const EVP_MD *type,unsigned char *md,unsigned int *len);
-int X509_REQ_digest(X509_REQ *data,const EVP_MD *type,unsigned char *md,unsigned int *len);
-int X509_NAME_digest(X509_NAME *data,const EVP_MD *type,
-	unsigned char *md,unsigned int *len);
+int X509_digest(const X509 *data,const EVP_MD *type,
+		unsigned char *md, unsigned int *len);
+int X509_CRL_digest(const X509_CRL *data,const EVP_MD *type,
+		unsigned char *md, unsigned int *len);
+int X509_REQ_digest(const X509_REQ *data,const EVP_MD *type,
+		unsigned char *md, unsigned int *len);
+int X509_NAME_digest(const X509_NAME *data,const EVP_MD *type,
+		unsigned char *md, unsigned int *len);
 #endif
 
 #ifndef NO_FP_API
@@ -963,20 +966,20 @@ int X509_REQ_add1_attr_by_txt(X509_REQ *req,
 
 int		X509_check_private_key(X509 *x509,EVP_PKEY *pkey);
 
-int		X509_issuer_and_serial_cmp(X509 *a, X509 *b);
+int		X509_issuer_and_serial_cmp(const X509 *a, const X509 *b);
 unsigned long	X509_issuer_and_serial_hash(X509 *a);
 
-int		X509_issuer_name_cmp(X509 *a, X509 *b);
+int		X509_issuer_name_cmp(const X509 *a, const X509 *b);
 unsigned long	X509_issuer_name_hash(X509 *a);
 
-int		X509_subject_name_cmp(X509 *a,X509 *b);
+int		X509_subject_name_cmp(const X509 *a, const X509 *b);
 unsigned long	X509_subject_name_hash(X509 *x);
 
-int		X509_cmp (X509 *a, X509 *b);
-int		X509_NAME_cmp (X509_NAME *a, X509_NAME *b);
+int		X509_cmp(const X509 *a, const X509 *b);
+int		X509_NAME_cmp(const X509_NAME *a, const X509_NAME *b);
 unsigned long	X509_NAME_hash(X509_NAME *x);
 
-int		X509_CRL_cmp(X509_CRL *a,X509_CRL *b);
+int		X509_CRL_cmp(const X509_CRL *a, const X509_CRL *b);
 #ifndef NO_FP_API
 int		X509_print_fp(FILE *bp,X509 *x);
 int		X509_CRL_print_fp(FILE *bp,X509_CRL *x);
diff --git a/crypto/x509/x509_cmp.c b/crypto/x509/x509_cmp.c
index a8a5ca8b03..0452b025b9 100644
--- a/crypto/x509/x509_cmp.c
+++ b/crypto/x509/x509_cmp.c
@@ -63,7 +63,7 @@
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>
 
-int X509_issuer_and_serial_cmp(X509 *a, X509 *b)
+int X509_issuer_and_serial_cmp(const X509 *a, const X509 *b)
 	{
 	int i;
 	X509_CINF *ai,*bi;
@@ -97,17 +97,17 @@ unsigned long X509_issuer_and_serial_hash(X509 *a)
 	}
 #endif
 	
-int X509_issuer_name_cmp(X509 *a, X509 *b)
+int X509_issuer_name_cmp(const X509 *a, const X509 *b)
 	{
 	return(X509_NAME_cmp(a->cert_info->issuer,b->cert_info->issuer));
 	}
 
-int X509_subject_name_cmp(X509 *a, X509 *b)
+int X509_subject_name_cmp(const X509 *a, const X509 *b)
 	{
 	return(X509_NAME_cmp(a->cert_info->subject,b->cert_info->subject));
 	}
 
-int X509_CRL_cmp(X509_CRL *a, X509_CRL *b)
+int X509_CRL_cmp(const X509_CRL *a, const X509_CRL *b)
 	{
 	return(X509_NAME_cmp(a->crl->issuer,b->crl->issuer));
 	}
@@ -139,19 +139,25 @@ unsigned long X509_subject_name_hash(X509 *x)
 
 #ifndef NO_SHA
 /* Compare two certificates: they must be identical for
- * this to work.
+ * this to work. NB: Although "cmp" operations are generally
+ * prototyped to take "const" arguments (eg. for use in
+ * STACKs), the way X509 handling is - these operations may
+ * involve ensuring the hashes are up-to-date and ensuring
+ * certain cert information is cached. So this is the point
+ * where the "depth-first" constification tree has to halt
+ * with an evil cast.
  */
-int X509_cmp(X509 *a, X509 *b)
+int X509_cmp(const X509 *a, const X509 *b)
 {
 	/* ensure hash is valid */
-	X509_check_purpose(a, -1, 0);
-	X509_check_purpose(b, -1, 0);
+	X509_check_purpose((X509 *)a, -1, 0);
+	X509_check_purpose((X509 *)b, -1, 0);
 
 	return memcmp(a->sha1_hash, b->sha1_hash, SHA_DIGEST_LENGTH);
 }
 #endif
 
-int X509_NAME_cmp(X509_NAME *a, X509_NAME *b)
+int X509_NAME_cmp(const X509_NAME *a, const X509_NAME *b)
 	{
 	int i,j;
 	X509_NAME_ENTRY *na,*nb;
diff --git a/crypto/x509/x509_trs.c b/crypto/x509/x509_trs.c
index c779aaf94d..8637e56d9c 100644
--- a/crypto/x509/x509_trs.c
+++ b/crypto/x509/x509_trs.c
@@ -61,7 +61,8 @@
 #include <openssl/x509v3.h>
 
 
-static int tr_cmp(X509_TRUST **a, X509_TRUST **b);
+static int tr_cmp(const X509_TRUST * const *a,
+		const X509_TRUST * const *b);
 static void trtable_free(X509_TRUST *p);
 
 static int trust_1oidany(X509_TRUST *trust, X509 *x, int flags);
@@ -88,7 +89,8 @@ IMPLEMENT_STACK_OF(X509_TRUST)
 
 static STACK_OF(X509_TRUST) *trtable = NULL;
 
-static int tr_cmp(X509_TRUST **a, X509_TRUST **b)
+static int tr_cmp(const X509_TRUST * const *a,
+		const X509_TRUST * const *b)
 {
 	return (*a)->trust - (*b)->trust;
 }
diff --git a/crypto/x509/x_all.c b/crypto/x509/x_all.c
index b67ca243dc..dd5796e205 100644
--- a/crypto/x509/x_all.c
+++ b/crypto/x509/x_all.c
@@ -411,25 +411,25 @@ X509_NAME_ENTRY *X509_NAME_ENTRY_dup(X509_NAME_ENTRY *ne)
 		(char *(*)())d2i_X509_NAME_ENTRY,(char *)ne));
 	}
 
-int X509_digest(X509 *data, const EVP_MD *type, unsigned char *md,
+int X509_digest(const X509 *data, const EVP_MD *type, unsigned char *md,
 	     unsigned int *len)
 	{
 	return(ASN1_digest((int (*)())i2d_X509,type,(char *)data,md,len));
 	}
 
-int X509_CRL_digest(X509_CRL *data, const EVP_MD *type, unsigned char *md,
+int X509_CRL_digest(const X509_CRL *data, const EVP_MD *type, unsigned char *md,
 	     unsigned int *len)
 	{
 	return(ASN1_digest((int (*)())i2d_X509_CRL,type,(char *)data,md,len));
 	}
 
-int X509_REQ_digest(X509_REQ *data, const EVP_MD *type, unsigned char *md,
+int X509_REQ_digest(const X509_REQ *data, const EVP_MD *type, unsigned char *md,
 	     unsigned int *len)
 	{
 	return(ASN1_digest((int (*)())i2d_X509_REQ,type,(char *)data,md,len));
 	}
 
-int X509_NAME_digest(X509_NAME *data, const EVP_MD *type, unsigned char *md,
+int X509_NAME_digest(const X509_NAME *data, const EVP_MD *type, unsigned char *md,
 	     unsigned int *len)
 	{
 	return(ASN1_digest((int (*)())i2d_X509_NAME,type,(char *)data,md,len));