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Fix "dig +nssearch" indefinitely hanging issue

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When finishing the NSSEARCH task and there is no more followup
lookups to start, dig does not destroy the last lookup, which
causes it to hang indefinitely.

Rename the unused `first_pass` member of `dig_query_t` to `started`
and make it `true` in the first callback after `start_udp()` or
`start_tcp()` of the query to indicate that the query has been
started.

Create a new `check_if_queries_done()` function to check whether
all of the queries inside a lookup have been started and finished,
or canceled.

Use the mentioned function in the TRACE code block in `recv_done()`
to check whether the current query is the last one in the lookup and
cancel the lookup in that case to free the resources.
This commit is contained in:
Aram Sargsyan 2022-03-20 13:54:39 +00:00 committed by Arаm Sаrgsyаn
parent 5b76f0f80e
commit 7d360bd05e
2 changed files with 37 additions and 4 deletions
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39
bin/dig/dighost.c
View File

@ -1551,6 +1551,30 @@ check_if_done(void) {
}
}
/*%
* Check if we're done with all the queries in the lookup, except for
* the `except_q` query (can be NULL if no exception is required).
* Expects `l` to be a valid and locked lookup.
*/
static bool
check_if_queries_done(dig_lookup_t *l, dig_query_t *except_q) {
dig_query_t *q = ISC_LIST_HEAD(l->q);
debug("check_if_queries_done(%p)", l);
while (q != NULL) {
if (!q->started || isc_refcount_current(&q->references) > 1) {
if (!q->canceled && q != except_q) {
debug("there is a pending query %p", q);
return (false);
}
}
q = ISC_LIST_NEXT(q, link);
}
return (true);
}
static void
_destroy_lookup(dig_lookup_t *lookup) {
dig_server_t *s;
@ -2126,7 +2150,6 @@ _new_query(dig_lookup_t *lookup, char *servname, char *userarg,
*query = (dig_query_t){ .sendbuf = lookup->renderbuf,
.servname = servname,
.userarg = userarg,
.first_pass = true,
.warn_id = true,
.recvspace = isc_mem_get(mctx, COMMSIZE),
.tmpsendspace = isc_mem_get(mctx, COMMSIZE) };
@ -3074,6 +3097,8 @@ udp_ready(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
dig_query_t *readquery = NULL;
int local_timeout = timeout * 1000;
query->started = true;
if (eresult == ISC_R_CANCELED || query->canceled) {
dig_lookup_t *l = query->lookup;
@ -3413,14 +3438,17 @@ tcp_connected(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
char sockstr[ISC_SOCKADDR_FORMATSIZE];
dig_lookup_t *l = NULL;
REQUIRE(DIG_VALID_QUERY(query));
REQUIRE(query->handle == NULL);
debug("tcp_connected()");
query->started = true;
if (atomic_load(&cancel_now)) {
return;
}
REQUIRE(DIG_VALID_QUERY(query));
REQUIRE(query->handle == NULL);
INSIST(!free_now);
debug("tcp_connected(%p, %s, %p)", handle, isc_result_totext(eresult),
@ -4310,7 +4338,12 @@ recv_done(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
l->trace_root = false;
usesearch = false;
} else {
/*
* This is a query in the followup lookup
*/
dighost_printmessage(query, &b, msg, true);
docancel = check_if_queries_done(l, query);
}
}
}

2
bin/dig/dighost.h
View File

@ -194,7 +194,7 @@ struct dig_lookup {
struct dig_query {
unsigned int magic;
dig_lookup_t *lookup;
bool first_pass;
bool started;
bool first_soa_rcvd;
bool second_rr_rcvd;
bool first_repeat_rcvd;