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dns_cache: handle TTL=0 properly

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Existing entries should be expired, new entries should not be created.
This commit is contained in:
Martine Lenders 2022-08-11 14:04:16 +02:00
parent a93ba1ef80
commit 883c3fdffa
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GPG Key ID: 2134D77A5336DD80
1 changed files with 10 additions and 3 deletions
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13
sys/net/application_layer/dns/cache.c
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@ -174,14 +174,21 @@ void dns_cache_add(const char *domain_name, const void *addr_out,
DEBUG("dns_cache: lifetime of %s is %"PRIu32" s\n", domain_name, ttl);
mutex_lock(&cache_mutex);
/* iterate even if TTL = 0 just in case we need to expire */
for (unsigned i = 0; i < CONFIG_DNS_CACHE_SIZE; ++i) {
if (now > cache[i].expires || _is_empty(i)) {
if (ttl && (now > cache[i].expires || _is_empty(i))) {
_add_entry(i, hash, addr_out, addr_len, now + ttl);
goto exit;
}
if (cache[i].hash == hash && _get_len(i) == addr_len) {
DEBUG("dns_cache[%u] update ttl\n", i);
cache[i].expires = now + ttl;
if (ttl) {
cache[i].expires = now + ttl;
}
else {
/* put one second into past so that it is immediately expired */
cache[i].expires = now - 1;
}
goto exit;
}
uint32_t _ttl = cache[i].expires - now;
@ -191,7 +198,7 @@ void dns_cache_add(const char *domain_name, const void *addr_out,
}
}
if (idx >= 0) {
if (ttl && idx >= 0) {
DEBUG("dns_cache: evict first entry to expire\n");
_add_entry(idx, hash, addr_out, addr_len, now + ttl);
}