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Code Issues Releases Wiki Activity

minor refactoring of resume_qmin() for clarity

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make the code flow clearer by enumerating the result codes that
are treated as success conditions for an intermediate minimized
query (ISC_R_SUCCESS, DNS_R_DELEGATION, DNS_R_NXRRSET, etc), rather
than just folding them all into the 'default' branch of a switch
statement.
This commit is contained in:
Evan Hunt
2023-06-28 09:28:01 -07:00
parent 98d532abb9
commit 352d542d27
1 changed files with 37 additions and 18 deletions
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55
lib/dns/resolver.c
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@@ -4051,9 +4051,9 @@ fctx_try(fetchctx_t *fctx, bool retrying, bool badcache) {
}
/*
* Turn on NOFOLLOW in relaxed mode so that QNAME minimisation
* Turn on NOFOLLOW in relaxed mode so that QNAME minimization
* doesn't cause additional queries to resolve the target of the
* QNAME minimisation request when a referral is returned. This
* QNAME minimization request when a referral is returned. This
* will also reduce the impact of mis-matched NS RRsets where
* the child's NS RRset is garbage. If a delegation is
* discovered DNS_R_DELEGATION will be returned to resume_qmin.
@@ -4150,31 +4150,50 @@ resume_qmin(void *arg) {
case ISC_R_SHUTTINGDOWN:
case ISC_R_CANCELED:
goto cleanup;
case DNS_R_NXDOMAIN:
case DNS_R_NCACHENXDOMAIN:
case DNS_R_FORMERR:
case DNS_R_REMOTEFORMERR:
case ISC_R_FAILURE:
if ((fctx->options & DNS_FETCHOPT_QMIN_STRICT) == 0) {
/* Disable minimization in relaxed mode */
fctx->qmin_labels = DNS_NAME_MAXLABELS;
/*
* We store the result. If we succeed in the end
* we'll issue a warning that the server is
* broken.
*/
fctx->qmin_warning = result;
} else {
/* fail in strict mode */
if ((fctx->options & DNS_FETCHOPT_QMIN_STRICT) != 0) {
/* These results cause a hard fail in strict mode */
goto cleanup;
}
break;
default:
/* ...or disable minimization in relaxed mode */
fctx->qmin_labels = DNS_NAME_MAXLABELS;
/*
* When DNS_FETCHOPT_NOFOLLOW is set and a delegation
* was discovered, DNS_R_DELEGATION is returned and is
* processed here.
* We store the result. If we succeed in the end
* we'll issue a warning that the server is
* broken.
*/
fctx->qmin_warning = result;
break;
case ISC_R_SUCCESS:
case DNS_R_DELEGATION:
case DNS_R_NXRRSET:
case DNS_R_NCACHENXRRSET:
case DNS_R_CNAME:
case DNS_R_DNAME:
/*
* Any other result will *not* cause a failure in strict
* mode, or cause minimization to be disabled in relaxed
* mode.
*
* If DNS_R_DELEGATION is set here, it implies that
* DNS_FETCHOPT_NOFOLLOW was set, and a delegation was
* discovered but not followed; we will do so now.
*/
break;
default:
isc_log_write(dns_lctx, DNS_LOGCATEGORY_RESOLVER,
DNS_LOGMODULE_RESOLVER, ISC_LOG_DEBUG(5),
"QNAME minimization: unexpected result %s",
isc_result_totext(result));
break;
}