Rewrite asn1_item_ex_d2i_choice() using CBS.

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

ok tb@

1 files changed, 54 insertions, 73 deletions

diff --git a/src/lib/libcrypto/asn1/tasn_dec.c b/src/lib/libcrypto/asn1/tasn_dec.c
index 69e27a9f0f..db4424b6be 100644
--- a/src/lib/libcrypto/asn1/tasn_dec.c
+++ b/src/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: