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Fixed bug #36899 DNS TTL 0 is cached for a long time

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This commit is contained in:
goldsimon 2012-08-13 21:32:44 +02:00
parent a070751061
commit 556a2126b5
2 changed files with 12 additions and 1 deletions
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3
CHANGELOG
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@ -80,6 +80,9 @@ HISTORY
++ Bugfixes:
2012-08-13: Simon Goldschmidt
* dns.c: fixed bug #36899 DNS TTL 0 is cached for a long time
2012-05-11: Simon Goldschmidt (patch by Marty)
* memp.c: fixed bug #36412: memp.c does not compile when
MEMP_OVERFLOW_CHECK > zero and MEMP_SEPARATE_POOLS == 1

10
src/core/dns.c
View File

@ -694,7 +694,7 @@ dns_check_entry(u8_t i)
case DNS_STATE_DONE: {
/* if the time to live is nul */
if (--pEntry->ttl == 0) {
if ((pEntry->ttl == 0) || (--pEntry->ttl == 0)) {
LWIP_DEBUGF(DNS_DEBUG, ("dns_check_entry: \"%s\": flush\n", pEntry->name));
/* flush this entry */
pEntry->state = DNS_STATE_UNUSED;
@ -816,6 +816,13 @@ dns_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *addr, u16_t
if (pEntry->found) {
(*pEntry->found)(pEntry->name, &pEntry->ipaddr, pEntry->arg);
}
if (pEntry->ttl == 0) {
/* RFC 883, page 29: "Zero values are
interpreted to mean that the RR can only be used for the
transaction in progress, and should not be cached."
-> flush this entry now */
goto flushentry;
}
/* deallocate memory and return */
goto memerr;
} else {
@ -838,6 +845,7 @@ responseerr:
if (pEntry->found) {
(*pEntry->found)(pEntry->name, NULL, pEntry->arg);
}
flushentry:
/* flush this entry */
pEntry->state = DNS_STATE_UNUSED;
pEntry->found = NULL;