Rewrite asn1_item_ex_d2i_choice() using CBS.

Now that combine no longer exists, we can also free and reallocate.

ok tb@

diff --git a/lib/libcrypto/asn1/tasn_dec.c b/lib/libcrypto/asn1/tasn_dec.c
index 69e27a9..db4424b 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 1.65 2022/05/12 19:33:19 jsing Exp $ */
+/* $OpenBSD: tasn_dec.c,v 1.66 2022/05/12 19:52:31 jsing Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2000.
  */
@@ -125,119 +125,100 @@ ASN1_template_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
 }
 
 static int
-asn1_item_ex_d2i_choice(ASN1_VALUE **pval, const unsigned char **in, long len,
-    const ASN1_ITEM *it, int tag, int aclass, char opt, int depth)
+asn1_item_ex_d2i_choice(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
+    int tag_number, int tag_class, char optional, int depth)
 {
        const ASN1_TEMPLATE *tt, *errtt = NULL;
        const ASN1_AUX *aux = it->funcs;
        ASN1_aux_cb *asn1_cb = NULL;
+       ASN1_VALUE *achoice = NULL;
        ASN1_VALUE **pchptr;
-       const unsigned char *p = NULL;
-       int i;
-       int ret = 0;
+       int i, ret;
 
        if (it->itype != ASN1_ITYPE_CHOICE)
                goto err;
 
-       if (aux && aux->asn1_cb)
-               asn1_cb = aux->asn1_cb;
-
        /*
-        * It never makes sense for CHOICE types to have implicit
-        * tagging, so if tag != -1, then this looks like an error in
-        * the template.
+        * It never makes sense for CHOICE types to have implicit tagging, so
+        * if tag_number != -1, then this looks like an error in the template.
         */
-       if (tag != -1) {
+       if (tag_number != -1) {
                ASN1error(ASN1_R_BAD_TEMPLATE);
                goto err;
        }
 
-       if (asn1_cb && !asn1_cb(ASN1_OP_D2I_PRE, pval, it, NULL))
-               goto auxerr;
+       if (*pval != NULL) {
+               ASN1_item_ex_free(pval, it);
+               *pval = NULL;
+       }
 
-       if (*pval) {
-               /* Free up and zero CHOICE value if initialised */
-               i = asn1_get_choice_selector(pval, it);
-               if ((i >= 0) && (i < it->tcount)) {
-                       tt = it->templates + i;
-                       pchptr = asn1_get_field_ptr(pval, tt);
-                       ASN1_template_free(pchptr, tt);
-                       asn1_set_choice_selector(pval, -1, it);
-               }
-       } else if (!ASN1_item_ex_new(pval, it)) {
-               ASN1error(ERR_R_NESTED_ASN1_ERROR);
+       if (aux != NULL)
+               asn1_cb = aux->asn1_cb;
+
+       if (asn1_cb != NULL && !asn1_cb(ASN1_OP_D2I_PRE, &achoice, it, NULL)) {
+               ASN1error(ASN1_R_AUX_ERROR);
                goto err;
        }
-       /* CHOICE type, try each possibility in turn */
-       p = *in;
+
+       if (achoice == NULL) {
+               if (!ASN1_item_ex_new(&achoice, it)) {
+                       ASN1error(ERR_R_NESTED_ASN1_ERROR);
+                       goto err;
+               }
+       }
+
+       /* Try each possible CHOICE in turn. */
        for (i = 0, tt = it->templates; i < it->tcount; i++, tt++) {
-               pchptr = asn1_get_field_ptr(pval, tt);
-               /* We mark field as OPTIONAL so its absence
-                * can be recognised.
-                */
-               ret = asn1_template_ex_d2i(pchptr, &p, len, tt, 1,
-                   depth);
+               pchptr = asn1_get_field_ptr(&achoice, tt);
+
+               /* Mark field as OPTIONAL so its absence can be identified. */
+               ret = asn1_template_ex_d2i_cbs(pchptr, cbs, tt, 1, depth);
+
                /* If field not present, try the next one */
                if (ret == -1)
                        continue;
-               /* If positive return, read OK, break loop */
-               if (ret > 0)
-                       break;
-               /* Otherwise must be an ASN1 parsing error */
-               errtt = tt;
-               ASN1error(ERR_R_NESTED_ASN1_ERROR);
-               goto err;
+
+               if (ret != 1) {
+                       ASN1error(ERR_R_NESTED_ASN1_ERROR);
+                       errtt = tt;
+                       goto err;
+               }
+
+               /* We've successfully decoded an ASN.1 object. */
+               asn1_set_choice_selector(&achoice, i, it);
+               break;
        }
 
        /* Did we fall off the end without reading anything? */
        if (i == it->tcount) {
-               /* If OPTIONAL, this is OK */
-               if (opt) {
-                       /* Free and zero it */
-                       ASN1_item_ex_free(pval, it);
+               if (optional) {
+                       ASN1_item_ex_free(&achoice, it);
                        return -1;
                }
                ASN1error(ASN1_R_NO_MATCHING_CHOICE_TYPE);
                goto err;
        }
 
-       asn1_set_choice_selector(pval, i, it);
-       *in = p;
-       if (asn1_cb && !asn1_cb(ASN1_OP_D2I_POST, pval, it, NULL))
-               goto auxerr;
+       if (asn1_cb != NULL && !asn1_cb(ASN1_OP_D2I_POST, &achoice, it, NULL)) {
+               ASN1error(ASN1_R_AUX_ERROR);
+               goto err;
+       }
+
+       *pval = achoice;
+       achoice = NULL;
+
        return 1;
 
- auxerr:
-       ASN1error(ASN1_R_AUX_ERROR);
  err:
-       ASN1_item_ex_free(pval, it);
+       ASN1_item_ex_free(&achoice, it);
 
        if (errtt)
                ERR_asprintf_error_data("Field=%s, Type=%s", errtt->field_name,
                    it->sname);
        else
                ERR_asprintf_error_data("Type=%s", it->sname);
-       return 0;
-}
 
-static int
-asn1_item_ex_d2i_choice_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
-    int tag_number, int tag_class, char optional, int depth)
-{
-       const unsigned char *p;
-       int ret;
-
-       if (CBS_len(cbs) > LONG_MAX)
-               return 0;
-
-       p = CBS_data(cbs);
-       ret = asn1_item_ex_d2i_choice(pval, &p, (long)CBS_len(cbs), it,
-           tag_number, tag_class, optional, depth);
-       if (ret == 1) {
-               if (!CBS_skip(cbs, p - CBS_data(cbs)))
-                       return 0;
-       }
-       return ret;
+       return 0;
 }
 
 static int
@@ -518,7 +499,7 @@ asn1_item_ex_d2i_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
                return ret;
 
        case ASN1_ITYPE_CHOICE:
-               return asn1_item_ex_d2i_choice_cbs(pval, cbs, it, tag_number,
+               return asn1_item_ex_d2i_choice(pval, cbs, it, tag_number,
                    tag_class, optional, depth);
 
        case ASN1_ITYPE_NDEF_SEQUENCE: