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to avoid any possibility of the pipe getting full and blocking we now

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only allow one query in the async dns pipe at a time. The others are
queued in the parent.
This commit is contained in:
Andrew Tridgell 0001-01-01 00:00:00 +00:00
parent cc6e770663
commit f1004dd52a
1 changed files with 58 additions and 27 deletions
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85
source/nmbd/asyncdns.c
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@ -67,9 +67,11 @@ struct query_record {
struct in_addr result;
};
/* a queue of pending requests waiting for DNS responses */
/* a queue of pending requests waiting to be sent to the DNS child */
static struct packet_struct *dns_queue;
/* the packet currently being processed by the dns child */
static struct packet_struct *dns_current;
/***************************************************************************
@ -140,20 +142,26 @@ void start_async_dns(void)
/***************************************************************************
check if a particular name is already being queried
****************************************************************************/
static BOOL query_in_queue(struct query_record *r)
static BOOL query_current(struct query_record *r)
{
struct packet_struct *p;
for (p = dns_queue; p; p = p->next) {
struct nmb_packet *nmb = &p->packet.nmb;
struct nmb_name *question = &nmb->question.question_name;
if (name_equal(question, &r->name))
return True;
}
return False;
return dns_current &&
name_equal(&r->name,
&dns_current->packet.nmb.question.question_name);
}
/***************************************************************************
write a query to the child process
****************************************************************************/
static BOOL write_child(struct packet_struct *p)
{
struct query_record r;
r.name = p->packet.nmb.question.question_name;
return write_data(fd_out, (char *)&r, sizeof(r)) == sizeof(r);
}
/***************************************************************************
check the DNS queue
****************************************************************************/
@ -173,6 +181,19 @@ void run_dns_queue(void)
add_dns_result(&r.name, r.result);
if (dns_current) {
if (query_current(&r)) {
DEBUG(3,("DNS calling reply_name_query\n"));
in_dns = 1;
reply_name_query(dns_current);
in_dns = 0;
}
dns_current->locked = False;
free_packet(dns_current);
dns_current = NULL;
}
/* loop over the whole dns queue looking for entries that
match the result we just got */
for (p = dns_queue; p;) {
@ -200,6 +221,18 @@ void run_dns_queue(void)
}
}
if (dns_queue) {
dns_current = dns_queue;
dns_queue = dns_queue->next;
if (dns_queue) dns_queue->prev = NULL;
dns_current->next = NULL;
if (!write_child(dns_current)) {
DEBUG(3,("failed to send DNS query to child!\n"));
return;
}
}
}
/***************************************************************************
@ -208,27 +241,25 @@ queue a DNS query
BOOL queue_dns_query(struct packet_struct *p,struct nmb_name *question,
struct name_record **n)
{
struct query_record r;
if (in_dns || fd_in == -1)
return False;
r.name = *question;
if (!query_in_queue(&r) &&
!write_data(fd_out, (char *)&r, sizeof(r))) {
DEBUG(3,("failed to send DNS query to child!\n"));
return False;
if (!dns_current) {
if (!write_child(p)) {
DEBUG(3,("failed to send DNS query to child!\n"));
return False;
}
dns_current = p;
p->locked = True;
} else {
p->locked = True;
p->next = dns_queue;
p->prev = NULL;
if (p->next)
p->next->prev = p;
dns_queue = p;
}
p->locked = True;
p->next = dns_queue;
p->prev = NULL;
if (p->next)
p->next->prev = p;
dns_queue = p;
DEBUG(3,("added DNS query for %s\n", namestr(question)));
return True;
}