validation with LYD_OPT_OBSOLETE ignores obsolete nodes

[olivier-matz-6wind]

Hi,

Calling lyd_validate() with the LYD_OPT_OBSOLETE flag does not return an error when the configuration contains an obsolete leaf. The following C file shows the issue:

#include <stdio.h>

#include <libyang/libyang.h>

const char *yang =
"module deprecation {\n"
"  yang-version 1.1;\n"
"\n"
"  namespace \"urn:deprecation\";\n"
"  prefix \"deprecation\";\n"
"\n"
"  container test-deprecation {\n"
"    leaf deprecated {\n"
"       type string;\n"
"       status deprecated;\n"
"    }\n"
"\n"
"    leaf obsolete {\n"
"       type string;\n"
"       status obsolete;\n"
"    }\n"
"  }\n"
"}\n"
;

const char *data =
"<test-deprecation xmlns=\"urn:deprecation\">"
  "<deprecated>foo</deprecated>"
  "<obsolete>bar</obsolete>"
"</test-deprecation>"
;

/* same than lyd_find_path() except it expects to match only one node */
static struct lyd_node *
lyd_find_path_one(const struct lyd_node *root, const char *path)
{
        struct ly_set *set = NULL;
        struct lyd_node *dnode;

        set = lyd_find_path(root, path);
        if (set == NULL)
                goto fail;
        if (set->number != 1)
                goto fail;
        dnode = set->set.d[0];
        ly_set_free(set);
        return dnode;

fail:
        ly_set_free(set);
        return NULL;
}

int main(void)
{
        const struct lys_module *mod;
        struct ly_ctx *ctx;
        struct lyd_node *conf, *dnode;
        int flags;

        /* libyang context */
        ctx = ly_ctx_new(NULL, 0);
        if (ctx == NULL) {
                fprintf(stderr, "Failed to create context.\n");
                return 1;
        }

        mod = lys_parse_mem(ctx, yang, LYS_IN_YANG);
        if (mod == NULL) {
                fprintf(stderr, "Failed to parse yang\n");
                return 1;
        }

        conf = lyd_parse_mem(ctx, data, LYD_XML, LYD_OPT_CONFIG);
        if (conf == NULL) {
                fprintf(stderr, "Failed to parse configuration\n");
                return 1;
        }

        lyd_print_file(stdout, conf, LYD_XML, LYP_FORMAT);
        dnode = lyd_find_path_one(conf,
                        "/deprecation:test-deprecation/obsolete");
        if (dnode == NULL) {
                fprintf(stderr, "Failed to retrieve obsolete node\n");
                return -1;
        }
        printf("Obsolete flag for '/test-deprecation/obsolete' node: %d\n",
                !!(dnode->schema->flags & LYS_STATUS_OBSLT));

        printf("== Check validation without obsolete flag:\n");
        flags = LYD_OPT_STRICT | LYD_OPT_CONFIG;
        ly_errno = LY_SUCCESS;
        if (lyd_validate(&conf, flags, ctx) < 0 || ly_errno != LY_SUCCESS) {
                printf("  Invalid configuration\n");
        } else {
                printf("  Valid configuration\n");
        }

        printf("== Check validation with obsolete flag:\n");
        flags |= LYD_OPT_OBSOLETE;
        ly_errno = LY_SUCCESS;
        if (lyd_validate(&conf, flags, ctx) < 0 || ly_errno != LY_SUCCESS) {
                printf("  Invalid configuration\n");
        } else {
                printf("  Valid configuration\n");
        }

        return 0;
}

Result of execution:

root@ubuntu1804:~$ gcc deprecation.c -lyang -Wall -Werror -Wextra
root@ubuntu1804:~$ ./a.out 
<test-deprecation xmlns="urn:deprecation">
  <deprecated>foo</deprecated>
  <obsolete>bar</obsolete>
</test-deprecation>
Obsolete flag for '/test-deprecation/obsolete' node: 1
== Check validation without obsolete flag:
  Valid configuration
== Check validation with obsolete flag:
  Valid configuration

Thanks,
Olivier

[michalvasko]

Hi Olivier,
the problem here is validation caching. Whenever a data tree is validated (also happens after parsing), it is remembered. When you validate it the next time, the nodes that were not changed are not validated it again. It is true that this approach only works correctly when you are always using the same validation flags, but that is a reasonable expectation.

So, if you want to see the error, use

conf = lyd_parse_mem(ctx, data, LYD_XML, LYD_OPT_CONFIG | LYD_OPT_OBSOLETE);

Regards,
Michal

[olivier-matz-6wind]

Hi Michal,

Thanks for the explanation, I can use this workaround.

Some more information about my use-case: our cli provides a "validate" command, with an optional parameter "check-obsolete". So, in my case, the flags are not always the same, they depend on the user input.

Regards,
Olivier

[michalvasko]

Hi Olivier,
I see. There are a number of solutions I can think of (check obsolete with LYD_OPT_OBSOLETE every time, introduce a new flag to force full revalidation, something else ...) but if you do not require it, we would like to keep it the way it is.

Regards,
Michal

[olivier-matz-6wind]

IMHO, the current behavior can be confusing for the libyang user.
That said, the workaround you proposed solves my problem, so I'm fine with it.

Thanks!