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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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43
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 * 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 * will also reduce the impact of mis-matched NS RRsets where
* the child's NS RRset is garbage. If a delegation is * the child's NS RRset is garbage. If a delegation is
* discovered DNS_R_DELEGATION will be returned to resume_qmin. * discovered DNS_R_DELEGATION will be returned to resume_qmin.
@@ -4150,32 +4150,51 @@ resume_qmin(void *arg) {
case ISC_R_SHUTTINGDOWN: case ISC_R_SHUTTINGDOWN:
case ISC_R_CANCELED: case ISC_R_CANCELED:
goto cleanup; goto cleanup;
case DNS_R_NXDOMAIN: case DNS_R_NXDOMAIN:
case DNS_R_NCACHENXDOMAIN: case DNS_R_NCACHENXDOMAIN:
case DNS_R_FORMERR: case DNS_R_FORMERR:
case DNS_R_REMOTEFORMERR: case DNS_R_REMOTEFORMERR:
case ISC_R_FAILURE: case ISC_R_FAILURE:
if ((fctx->options & DNS_FETCHOPT_QMIN_STRICT) == 0) { if ((fctx->options & DNS_FETCHOPT_QMIN_STRICT) != 0) {
/* Disable minimization in relaxed mode */ /* These results cause a hard fail in strict mode */
goto cleanup;
}
/* ...or disable minimization in relaxed mode */
fctx->qmin_labels = DNS_NAME_MAXLABELS; fctx->qmin_labels = DNS_NAME_MAXLABELS;
/* /*
* We store the result. If we succeed in the end * We store the result. If we succeed in the end
* we'll issue a warning that the server is * we'll issue a warning that the server is
* broken. * broken.
*/ */
fctx->qmin_warning = result; fctx->qmin_warning = result;
} else {
/* fail in strict mode */
goto cleanup;
}
break; break;
default:
case ISC_R_SUCCESS:
case DNS_R_DELEGATION:
case DNS_R_NXRRSET:
case DNS_R_NCACHENXRRSET:
case DNS_R_CNAME:
case DNS_R_DNAME:
/* /*
* When DNS_FETCHOPT_NOFOLLOW is set and a delegation * Any other result will *not* cause a failure in strict
* was discovered, DNS_R_DELEGATION is returned and is * mode, or cause minimization to be disabled in relaxed
* processed here. * 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; 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;
} }
if (dns_rdataset_isassociated(&fctx->nameservers)) { if (dns_rdataset_isassociated(&fctx->nameservers)) {