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resolved: include SOA records in LLMNR replies for non-existing RRs to allow negative caching

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This commit is contained in:
Lennart Poettering 2014-07-30 16:30:25 +02:00
parent ab0cf8f8ff
commit 8bf52d3d17
7 changed files with 107 additions and 42 deletions
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24
src/resolve/resolved-dns-answer.c
View file

@ -97,6 +97,30 @@ int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr) {
return 1;
}
int dns_answer_add_soa(DnsAnswer *a, const char *name) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *soa = NULL;
soa = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SOA, name);
if (!soa)
return -ENOMEM;
soa->soa.mname = strdup(name);
if (!soa->soa.mname)
return -ENOMEM;
soa->soa.rname = strappend("root.", name);
if (!soa->soa.rname)
return -ENOMEM;
soa->soa.serial = 1;
soa->soa.refresh = 1;
soa->soa.retry = 1;
soa->soa.expire = 1;
soa->soa.minimum = 1;
return dns_answer_add(a, soa);
}
int dns_answer_contains(DnsAnswer *a, DnsResourceKey *key) {
unsigned i;
int r;

1
src/resolve/resolved-dns-answer.h
View file

@ -38,6 +38,7 @@ DnsAnswer *dns_answer_ref(DnsAnswer *a);
DnsAnswer *dns_answer_unref(DnsAnswer *a);
int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr);
int dns_answer_add_soa(DnsAnswer *a, const char *name);
int dns_answer_contains(DnsAnswer *a, DnsResourceKey *key);
int dns_answer_find_soa(DnsAnswer *a, DnsResourceKey *key, DnsResourceRecord **ret);

10
src/resolve/resolved-dns-rr.c
View file

@ -172,6 +172,16 @@ DnsResourceRecord* dns_resource_record_new(DnsResourceKey *key) {
return rr;
}
DnsResourceRecord* dns_resource_record_new_full(uint16_t class, uint16_t type, const char *name) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
key = dns_resource_key_new(class, type, name);
if (!key)
return NULL;
return dns_resource_record_new(key);
}
DnsResourceRecord* dns_resource_record_ref(DnsResourceRecord *rr) {
if (!rr)
return NULL;

1
src/resolve/resolved-dns-rr.h
View file

@ -140,6 +140,7 @@ int dns_resource_key_compare_func(const void *a, const void *b);
DEFINE_TRIVIAL_CLEANUP_FUNC(DnsResourceKey*, dns_resource_key_unref);
DnsResourceRecord* dns_resource_record_new(DnsResourceKey *key);
DnsResourceRecord* dns_resource_record_new_full(uint16_t class, uint16_t type, const char *name);
DnsResourceRecord* dns_resource_record_ref(DnsResourceRecord *rr);
DnsResourceRecord* dns_resource_record_unref(DnsResourceRecord *rr);
int dns_resource_record_new_reverse(DnsResourceRecord **ret, int family, const union in_addr_union *address, const char *name);

28
src/resolve/resolved-dns-scope.c
View file

@ -389,14 +389,14 @@ int dns_scope_good_dns_server(DnsScope *s, int family, const union in_addr_union
return !!manager_find_dns_server(s->manager, family, address);
}
static int dns_scope_make_reply_packet(DnsScope *s, uint16_t id, int rcode, DnsQuestion *q, DnsAnswer *a, DnsPacket **ret) {
static int dns_scope_make_reply_packet(DnsScope *s, uint16_t id, int rcode, DnsQuestion *q, DnsAnswer *answer, DnsAnswer *soa, DnsPacket **ret) {
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
unsigned i;
int r;
assert(s);
if (q->n_keys <= 0 && a->n_rrs <= 0)
if (q->n_keys <= 0 && answer->n_rrs <= 0 && soa->n_rrs <= 0)
return -EINVAL;
r = dns_packet_new(&p, s->protocol, 0);
@ -425,14 +425,24 @@ static int dns_scope_make_reply_packet(DnsScope *s, uint16_t id, int rcode, DnsQ
DNS_PACKET_HEADER(p)->qdcount = htobe16(q->n_keys);
}
if (a) {
for (i = 0; i < a->n_rrs; i++) {
r = dns_packet_append_rr(p, a->rrs[i], NULL);
if (answer) {
for (i = 0; i < answer->n_rrs; i++) {
r = dns_packet_append_rr(p, answer->rrs[i], NULL);
if (r < 0)
return r;
}
DNS_PACKET_HEADER(p)->ancount = htobe16(a->n_rrs);
DNS_PACKET_HEADER(p)->ancount = htobe16(answer->n_rrs);
}
if (soa) {
for (i = 0; i < soa->n_rrs; i++) {
r = dns_packet_append_rr(p, soa->rrs[i], NULL);
if (r < 0)
return r;
}
DNS_PACKET_HEADER(p)->arcount = htobe16(soa->n_rrs);
}
*ret = p;
@ -443,7 +453,7 @@ static int dns_scope_make_reply_packet(DnsScope *s, uint16_t id, int rcode, DnsQ
void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
_cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
int r, fd;
assert(s);
@ -475,7 +485,7 @@ void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
return;
}
r = dns_zone_lookup(&s->zone, p->question, &answer);
r = dns_zone_lookup(&s->zone, p->question, &answer, &soa);
if (r < 0) {
log_debug("Failed to lookup key: %s", strerror(-r));
return;
@ -485,7 +495,7 @@ void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 0);
r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, &reply);
r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, &reply);
if (r < 0) {
log_debug("Failed to build reply packet: %s", strerror(-r));
return;

83
src/resolve/resolved-dns-zone.c
View file

@ -192,21 +192,23 @@ int dns_zone_put(DnsZone *z, DnsResourceRecord *rr) {
return 0;
}
int dns_zone_lookup(DnsZone *z, DnsQuestion *q, DnsAnswer **ret) {
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
bool has_other_rrs = false;
unsigned i, n = 0;
int dns_zone_lookup(DnsZone *z, DnsQuestion *q, DnsAnswer **ret_answer, DnsAnswer **ret_soa) {
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
unsigned i, n_answer = 0, n_soa = 0;
int r;
assert(z);
assert(q);
assert(ret);
assert(ret_answer);
assert(ret_soa);
if (q->n_keys <= 0) {
*ret = NULL;
*ret_answer = NULL;
*ret_soa = NULL;
return 0;
}
/* First iteration, count what we have */
for (i = 0; i < q->n_keys; i++) {
DnsZoneItem *j;
@ -220,40 +222,46 @@ int dns_zone_lookup(DnsZone *z, DnsQuestion *q, DnsAnswer **ret) {
j = hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(q->keys[i]));
LIST_FOREACH(by_name, j, j) {
has_other_rrs = true;
k = dns_resource_key_match_rr(q->keys[i], j->rr);
if (k < 0)
return k;
if (k == 0)
continue;
n++;
n_soa++;
else
n_answer++;
}
} else {
j = hashmap_get(z->by_key, q->keys[i]);
if (!j) {
if (j) {
LIST_FOREACH(by_key, j, j)
n_answer++;
} else {
if (hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(q->keys[i])))
has_other_rrs = true;
continue;
n_soa ++;
}
LIST_FOREACH(by_key, j, j)
n++;
}
}
if (n <= 0) {
*ret = NULL;
return has_other_rrs;
if (n_answer <= 0 && n_soa <= 0) {
*ret_answer = NULL;
*ret_soa = NULL;
return 0;
}
answer = dns_answer_new(n);
if (!answer)
return -ENOMEM;
if (n_answer > 0) {
answer = dns_answer_new(n_answer);
if (!answer)
return -ENOMEM;
}
if (n_soa > 0) {
soa = dns_answer_new(n_soa);
if (!soa)
return -ENOMEM;
}
/* Second iteration, actually add the RRs to the answers */
for (i = 0; i < q->n_keys; i++) {
DnsZoneItem *j;
@ -267,25 +275,36 @@ int dns_zone_lookup(DnsZone *z, DnsQuestion *q, DnsAnswer **ret) {
if (k < 0)
return k;
if (k == 0)
continue;
r = dns_answer_add(answer, j->rr);
r = dns_answer_add_soa(soa, DNS_RESOURCE_KEY_NAME(q->keys[i]));
else
r = dns_answer_add(answer, j->rr);
if (r < 0)
return r;
}
} else {
j = hashmap_get(z->by_key, q->keys[i]);
LIST_FOREACH(by_key, j, j) {
r = dns_answer_add(answer, j->rr);
if (r < 0)
return r;
if (j) {
LIST_FOREACH(by_key, j, j) {
r = dns_answer_add(answer, j->rr);
if (r < 0)
return r;
}
} else {
if (hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(q->keys[i]))) {
r = dns_answer_add_soa(soa, DNS_RESOURCE_KEY_NAME(q->keys[i]));
if (r < 0)
return r;
}
}
}
}
*ret = answer;
*ret_answer = answer;
answer = NULL;
*ret_soa = soa;
soa = NULL;
return 1;
}

2
src/resolve/resolved-dns-zone.h
View file

@ -37,4 +37,4 @@ void dns_zone_flush(DnsZone *z);
int dns_zone_put(DnsZone *z, DnsResourceRecord *rr);
void dns_zone_remove_rr(DnsZone *z, DnsResourceRecord *rr);
int dns_zone_lookup(DnsZone *z, DnsQuestion *q, DnsAnswer **answer);
int dns_zone_lookup(DnsZone *z, DnsQuestion *q, DnsAnswer **answer, DnsAnswer **soa);