Refactor asn1_ex_c2i()

The asn1_ex_c2i() function currently handles the V_ASN1_ANY case inline,
which means there multiple special cases, with  pointer fudging and
restoring. Instead, split asn1_ex_c2i() into three functions - one that
only handles storage into a primitive type (asn1_ex_c2i_primitive()), one
that handles the V_ASN1_ANY case (asn1_ex_c2i_any()) and calls
asn1_ex_c2i_primitive() with the correct pointer and an asn1_ex_c2i()
that handles the custom functions case, before dispatching to
asn1_ex_c2i_any() or asn1_ex_c2i_primitive(), as appropriate.

This results in cleaner and simpler code.

With input from and ok tb@

diff --git a/lib/libcrypto/asn1/tasn_dec.c b/lib/libcrypto/asn1/tasn_dec.c
index 103774f..f04ec66 100644 (file)
--- a/lib/libcrypto/asn1/tasn_dec.c
+++ b/lib/libcrypto/asn1/tasn_dec.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tasn_dec.c,v 1.58 2022/05/05 19:18:56 jsing Exp $ */
+/* $OpenBSD: tasn_dec.c,v 1.59 2022/05/07 10:03:49 jsing Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2000.
  */
@@ -771,47 +771,21 @@ asn1_d2i_ex_primitive(ASN1_VALUE **pval, const unsigned char **in, long inlen,
        return ret;
 }
 
-/* Translate ASN.1 content octets into a structure. */
 static int
-asn1_ex_c2i(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *it)
+asn1_ex_c2i_primitive(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *it)
 {
-       ASN1_VALUE **opval = NULL;
        ASN1_STRING *stmp;
-       ASN1_TYPE *typ = NULL;
        ASN1_INTEGER **tint;
        ASN1_BOOLEAN *tbool;
        uint8_t u8val;
        int ret = 0;
 
-       if (CBS_len(content) > INT_MAX)
+       if (it->funcs != NULL)
                return 0;
 
-       if (it->funcs != NULL) {
-               const ASN1_PRIMITIVE_FUNCS *pf = it->funcs;
-               char free_content = 0;
-
-               if (pf->prim_c2i == NULL)
-                       return 0;
-
-               return pf->prim_c2i(pval, CBS_data(content), CBS_len(content),
-                   utype, &free_content, it);
-       }
+       if (CBS_len(content) > INT_MAX)
+               return 0;
 
-       /* If ANY type clear type and set pointer to internal value */
-       if (it->utype == V_ASN1_ANY) {
-               if (!*pval) {
-                       typ = ASN1_TYPE_new();
-                       if (typ == NULL)
-                               goto err;
-                       *pval = (ASN1_VALUE *)typ;
-               } else
-                       typ = (ASN1_TYPE *)*pval;
-
-               if (utype != typ->type)
-                       ASN1_TYPE_set(typ, utype, NULL);
-               opval = pval;
-               pval = &typ->value.asn1_value;
-       }
        switch (utype) {
        case V_ASN1_OBJECT:
                if (!c2i_ASN1_OBJECT_cbs((ASN1_OBJECT **)pval, content))
@@ -895,21 +869,67 @@ asn1_ex_c2i(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *it)
                }
                break;
        }
-       /* If ASN1_ANY and NULL type fix up value */
-       if (typ && (utype == V_ASN1_NULL))
-               typ->value.ptr = NULL;
 
        ret = 1;
 
  err:
-       if (!ret) {
-               ASN1_TYPE_free(typ);
-               if (opval)
-                       *opval = NULL;
-       }
        return ret;
 }
 
+static int
+asn1_ex_c2i_any(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *it)
+{
+       ASN1_TYPE *atype;
+
+       if (it->utype != V_ASN1_ANY || it->funcs != NULL)
+               return 0;
+
+       if (*pval != NULL) {
+               ASN1_TYPE_free((ASN1_TYPE *)*pval);
+               *pval = NULL;
+       }
+
+       if ((atype = ASN1_TYPE_new()) == NULL)
+               return 0;
+
+       if (!asn1_ex_c2i_primitive(&atype->value.asn1_value, content, utype, it)) {
+               ASN1_TYPE_free(atype);
+               return 0;
+       }
+       atype->type = utype;
+
+       /* Fix up value for ASN.1 NULL. */
+       if (atype->type == V_ASN1_NULL)
+               atype->value.ptr = NULL;
+
+       *pval = (ASN1_VALUE *)atype;
+
+       return 1;
+}
+
+static int
+asn1_ex_c2i(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *it)
+{
+       if (CBS_len(content) > INT_MAX)
+               return 0;
+
+       if (it->funcs != NULL) {
+               const ASN1_PRIMITIVE_FUNCS *pf = it->funcs;
+               char free_content = 0;
+
+               if (pf->prim_c2i == NULL)
+                       return 0;
+
+               return pf->prim_c2i(pval, CBS_data(content), CBS_len(content),
+                   utype, &free_content, it);
+       }
+
+       if (it->utype == V_ASN1_ANY)
+               return asn1_ex_c2i_any(pval, content, utype, it);
+
+       return asn1_ex_c2i_primitive(pval, content, utype, it);
+}
+
 /* Find the end of an ASN.1 object. */
 static int
 asn1_find_end(CBS *cbs, size_t length, char indefinite)