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After dig request errors, try to use other servers when they exist

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When timing-out or having other types of socket errors during a query,
dig isn't trying to perform the lookup using other servers which exist
in the lookup's queries list.

After configured amount of timeout retries, or after a socket error,
check if there are other queries/servers in the lookup's queries list,
and start the next one if it exists, instead of unconditionally failing.
This commit is contained in:
Aram Sargsyan
2022-03-11 19:37:27 +00:00
parent da0d85d748
commit bc203d6082
1 changed files with 101 additions and 32 deletions
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133
bin/dig/dighost.c
View File

@@ -3280,9 +3280,9 @@ tcp_connected(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
}
if (l->retries > 1) {
l->retries--;
debug("making new TCP request, %d tries left",
l->retries);
l->retries--;
requeue_lookup(l, true);
next = NULL;
} else if ((l->current_query != NULL) &&
@@ -3622,50 +3622,119 @@ recv_done(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
TIME_NOW(&query->time_recv);
}
if (eresult == ISC_R_TIMEDOUT && !l->tcp_mode && l->retries > 1) {
dig_query_t *newq = NULL;
l->retries--;
debug("making new UDP request, %d tries left", l->retries);
newq = new_query(l, query->servname, query->userarg);
ISC_LIST_INSERTAFTER(l->q, query, newq, link);
if (l->current_query == query) {
query_detach(&l->current_query);
}
start_udp(newq);
goto detach_query;
}
if ((!l->pending && !l->ns_search_only) || atomic_load(&cancel_now)) {
debug("no longer pending. Got %s", isc_result_totext(eresult));
goto next_lookup;
}
if (eresult != ISC_R_SUCCESS) {
if (eresult == ISC_R_TIMEDOUT) {
if (l->retries > 1 && !l->tcp_mode) {
dig_query_t *newq = NULL;
/*
* For UDP, insert a copy of the current query just
* after itself in the list, and start it to retry the
* request.
*/
newq = new_query(l, query->servname, query->userarg);
ISC_LIST_INSERTAFTER(l->q, query, newq, link);
if (l->current_query == query) {
query_detach(&l->current_query);
}
if (l->current_query == NULL) {
l->retries--;
debug("making new UDP request, %d tries left",
l->retries);
start_udp(newq);
}
goto detach_query;
} else if (l->retries > 1 && l->tcp_mode) {
/*
* For TCP, we have to requeue the whole lookup, see
* the comments above the start_tcp() function.
*/
l->retries--;
debug("making new TCP request, %d tries left",
l->retries);
requeue_lookup(l, true);
if (keep != NULL) {
isc_nmhandle_detach(&keep);
}
goto cancel_lookup;
} else {
dig_query_t *next = ISC_LIST_NEXT(query, link);
/*
* No retries left, go to the next query, if there is
* one.
*/
if (next != NULL) {
if (l->current_query == query) {
query_detach(&l->current_query);
}
if (l->current_query == NULL) {
debug("starting next query %p", next);
if (l->tcp_mode) {
start_tcp(next);
} else {
start_udp(next);
}
}
goto detach_query;
}
/*
* Otherwise, print the cmdline and an error message,
* and cancel the lookup.
*/
printf("%s", l->cmdline);
dighost_error("connection timed out; "
"no servers could be reached\n");
if (exitcode < 9) {
exitcode = 9;
}
if (keep != NULL) {
isc_nmhandle_detach(&keep);
}
goto cancel_lookup;
}
} else if (eresult != ISC_R_SUCCESS) {
dig_query_t *next = ISC_LIST_NEXT(query, link);
char sockstr[ISC_SOCKADDR_FORMATSIZE];
isc_sockaddr_format(&query->sockaddr, sockstr, sizeof(sockstr));
if (eresult == ISC_R_TIMEDOUT) {
if (l->retries > 1) {
debug("making new TCP request, %d tries left",
l->retries);
l->retries--;
requeue_lookup(l, true);
} else {
printf("%s", l->cmdline);
dighost_error("connection timed out; "
"no servers could be reached\n");
if (exitcode < 9) {
exitcode = 9;
/*
* There was a communication error with the current query,
* go to the next query, if there is one.
*/
if (next != NULL) {
if (l->current_query == query) {
query_detach(&l->current_query);
}
if (l->current_query == NULL) {
debug("starting next query %p", next);
if (l->tcp_mode) {
start_tcp(next);
} else {
start_udp(next);
}
}
} else {
dighost_error("communications error to %s: %s\n",
sockstr, isc_result_totext(eresult));
goto detach_query;
}
/*
* Otherwise, print an error message and cancel the
* lookup.
*/
dighost_error("communications error to %s: %s\n", sockstr,
isc_result_totext(eresult));
if (keep != NULL) {
isc_nmhandle_detach(&keep);
}