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resolved: optionally, allocate DnsResourceKey objects on the stack

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Sometimes when looking up entries in hashmaps indexed by a
DnsResourceKey it is helpful not having to allocate a full
DnsResourceKey dynamically just to use it as search key. Instead,
optionally allow allocation of a DnsResourceKey on the stack. Resource
keys allocated like that of course are subject to other lifetime cycles
than the usual Resource keys, hence initialize the reference counter to
to (unsigned) -1.

While we are at it, remove the prototype for
dns_resource_key_new_dname() which was never implemented.
This commit is contained in:
Lennart Poettering 2015-12-03 17:27:13 +01:00
parent 2a44bec4f6
commit 1b4f6e79ec
4 changed files with 28 additions and 30 deletions
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19
src/resolve/resolved-dns-cache.c
View file

@ -522,7 +522,6 @@ fail:
}
static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, DnsResourceKey *k) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *nsec_key = NULL, *cname_key = NULL;
DnsCacheItem *i;
const char *n;
int r;
@ -540,35 +539,23 @@ static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, D
n = DNS_RESOURCE_KEY_NAME(k);
/* Check if we have an NSEC record instead for the name. */
nsec_key = dns_resource_key_new(k->class, DNS_TYPE_NSEC, n);
if (!nsec_key)
return NULL;
i = hashmap_get(c->by_key, nsec_key);
i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_NSEC, n));
if (i)
return i;
/* Check if we have a CNAME record instead */
cname_key = dns_resource_key_new_cname(k);
if (!cname_key)
return NULL;
i = hashmap_get(c->by_key, cname_key);
i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_CNAME, n));
if (i)
return i;
/* OK, let's look for cached DNAME records. */
for (;;) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *dname_key = NULL;
char label[DNS_LABEL_MAX];
if (isempty(n))
return NULL;
dname_key = dns_resource_key_new(k->class, DNS_TYPE_DNAME, n);
if (!dname_key)
return NULL;
i = hashmap_get(c->by_key, dname_key);
i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_DNAME, n));
if (i)
return i;

11
src/resolve/resolved-dns-rr.c
View file

@ -51,12 +51,6 @@ DnsResourceKey* dns_resource_key_new(uint16_t class, uint16_t type, const char *
return k;
}
DnsResourceKey* dns_resource_key_new_cname(const DnsResourceKey *key) {
assert(key);
return dns_resource_key_new(key->class, DNS_TYPE_CNAME, DNS_RESOURCE_KEY_NAME(key));
}
DnsResourceKey* dns_resource_key_new_redirect(const DnsResourceKey *key, const DnsResourceRecord *cname) {
int r;
@ -137,6 +131,10 @@ DnsResourceKey* dns_resource_key_ref(DnsResourceKey *k) {
if (!k)
return NULL;
/* Static/const keys created with DNS_RESOURCE_KEY_CONST will
* set this to -1, they should not be reffed/unreffed */
assert(k->n_ref != (unsigned) -1);
assert(k->n_ref > 0);
k->n_ref++;
@ -147,6 +145,7 @@ DnsResourceKey* dns_resource_key_unref(DnsResourceKey *k) {
if (!k)
return NULL;
assert(k->n_ref != (unsigned) -1);
assert(k->n_ref > 0);
if (k->n_ref == 1) {

15
src/resolve/resolved-dns-rr.h
View file

@ -78,6 +78,19 @@ struct DnsResourceKey {
char *_name; /* don't access directy, use DNS_RESOURCE_KEY_NAME()! */
};
/* Creates a temporary resource key. This is only useful to quickly
* look up something, without allocating a full DnsResourceKey object
* for it. Note that it is not OK to take references to this kind of
* resource key object. */
#define DNS_RESOURCE_KEY_CONST(c, t, n) \
((DnsResourceKey) { \
.n_ref = (unsigned) -1, \
.class = c, \
.type = t, \
._name = (char*) n, \
})
struct DnsTxtItem {
size_t length;
LIST_FIELDS(DnsTxtItem, items);
@ -221,8 +234,6 @@ static inline const char* DNS_RESOURCE_KEY_NAME(const DnsResourceKey *key) {
}
DnsResourceKey* dns_resource_key_new(uint16_t class, uint16_t type, const char *name);
DnsResourceKey* dns_resource_key_new_cname(const DnsResourceKey *key);
DnsResourceKey* dns_resource_key_new_dname(const DnsResourceKey *key);
DnsResourceKey* dns_resource_key_new_redirect(const DnsResourceKey *key, const DnsResourceRecord *cname);
int dns_resource_key_new_append_suffix(DnsResourceKey **ret, DnsResourceKey *key, char *name);
DnsResourceKey* dns_resource_key_new_consume(uint16_t class, uint16_t type, char *name);

13
src/resolve/resolved-dns-zone.c
View file

@ -163,7 +163,6 @@ static int dns_zone_link_item(DnsZone *z, DnsZoneItem *i) {
}
static int dns_zone_item_probe_start(DnsZoneItem *i) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
DnsTransaction *t;
int r;
@ -172,12 +171,14 @@ static int dns_zone_item_probe_start(DnsZoneItem *i) {
if (i->probe_transaction)
return 0;
key = dns_resource_key_new(i->rr->key->class, DNS_TYPE_ANY, DNS_RESOURCE_KEY_NAME(i->rr->key));
if (!key)
return -ENOMEM;
t = dns_scope_find_transaction(i->scope, key, false);
t = dns_scope_find_transaction(i->scope, &DNS_RESOURCE_KEY_CONST(i->rr->key->class, DNS_TYPE_ANY, DNS_RESOURCE_KEY_NAME(i->rr->key)), false);
if (!t) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
key = dns_resource_key_new(i->rr->key->class, DNS_TYPE_ANY, DNS_RESOURCE_KEY_NAME(i->rr->key));
if (!key)
return -ENOMEM;
r = dns_transaction_new(&t, i->scope, key);
if (r < 0)
return r;