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resolved: announce DNS-SD records in mDNS scopes

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This commit is contained in:
Dmitry Rozhkov 2017-10-04 10:07:44 +03:00
parent 6db6a4642e
commit a2bf8a19cc
5 changed files with 107 additions and 8 deletions
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13
src/resolve/resolved-dns-rr.c
View file

@ -182,6 +182,19 @@ bool dns_resource_key_is_address(const DnsResourceKey *key) {
return key->class == DNS_CLASS_IN && IN_SET(key->type, DNS_TYPE_A, DNS_TYPE_AAAA);
}
bool dns_resource_key_is_dnssd_ptr(const DnsResourceKey *key) {
assert(key);
/* Check if this is a PTR resource key used in
Service Instance Enumeration as described in RFC6763 p4.1. */
if (key->type != DNS_TYPE_PTR)
return false;
return dns_name_endswith(dns_resource_key_name(key), "_tcp.local") ||
dns_name_endswith(dns_resource_key_name(key), "_udp.local");
}
int dns_resource_key_equal(const DnsResourceKey *a, const DnsResourceKey *b) {
int r;

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

@ -298,6 +298,7 @@ DnsResourceKey* dns_resource_key_ref(DnsResourceKey *key);
DnsResourceKey* dns_resource_key_unref(DnsResourceKey *key);
const char* dns_resource_key_name(const DnsResourceKey *key);
bool dns_resource_key_is_address(const DnsResourceKey *key);
bool dns_resource_key_is_dnssd_ptr(const DnsResourceKey *key);
int dns_resource_key_equal(const DnsResourceKey *a, const DnsResourceKey *b);
int dns_resource_key_match_rr(const DnsResourceKey *key, DnsResourceRecord *rr, const char *search_domain);
int dns_resource_key_match_cname_or_dname(const DnsResourceKey *key, const DnsResourceKey *cname, const char *search_domain);

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

@ -29,6 +29,7 @@
#include "random-util.h"
#include "resolved-dnssd.h"
#include "resolved-dns-scope.h"
#include "resolved-dns-zone.h"
#include "resolved-llmnr.h"
#include "resolved-mdns.h"
#include "socket-util.h"
@ -1065,7 +1066,12 @@ static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userda
int dns_scope_announce(DnsScope *scope, bool goodbye) {
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
LinkAddress *a;
_cleanup_set_free_ Set *types = NULL;
DnsTransaction *t;
DnsZoneItem *z;
unsigned size = 0;
Iterator iterator;
char *service_type;
int r;
if (!scope)
@ -1074,18 +1080,79 @@ int dns_scope_announce(DnsScope *scope, bool goodbye) {
if (scope->protocol != DNS_PROTOCOL_MDNS)
return 0;
answer = dns_answer_new(scope->link->n_addresses * 2);
/* Check if we're done with probing. */
LIST_FOREACH(transactions_by_scope, t, scope->transactions)
if (DNS_TRANSACTION_IS_LIVE(t->state))
return 0;
/* Calculate answer's size. */
HASHMAP_FOREACH(z, scope->zone.by_key, iterator) {
if (z->state != DNS_ZONE_ITEM_ESTABLISHED)
continue;
if (z->rr->key->type == DNS_TYPE_PTR &&
!dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) {
char key_str[DNS_RESOURCE_KEY_STRING_MAX];
log_debug("Skip PTR RR <%s> since its counterparts seem to be withdrawn", dns_resource_key_to_string(z->rr->key, key_str, sizeof key_str));
z->state = DNS_ZONE_ITEM_WITHDRAWN;
continue;
}
/* Collect service types for _services._dns-sd._udp.local RRs in a set */
if (!scope->announced &&
dns_resource_key_is_dnssd_ptr(z->rr->key)) {
if (!set_contains(types, dns_resource_key_name(z->rr->key))) {
r = set_ensure_allocated(&types, &dns_name_hash_ops);
if (r < 0)
return log_debug_errno(r, "Failed to allocate set: %m");
r = set_put(types, dns_resource_key_name(z->rr->key));
if (r < 0)
return log_debug_errno(r, "Failed to add item to set: %m");
}
}
size++;
}
answer = dns_answer_new(size + set_size(types));
if (!answer)
return log_oom();
LIST_FOREACH(addresses, a, scope->link->addresses) {
r = dns_answer_add(answer, a->mdns_address_rr, 0, goodbye ? DNS_ANSWER_GOODBYE : DNS_ANSWER_CACHE_FLUSH);
if (r < 0)
return log_debug_errno(r, "Failed to add address RR to answer: %m");
/* Second iteration, actually add RRs to the answer. */
HASHMAP_FOREACH(z, scope->zone.by_key, iterator) {
DnsAnswerFlags flags;
r = dns_answer_add(answer, a->mdns_ptr_rr, 0, goodbye ? DNS_ANSWER_GOODBYE : DNS_ANSWER_CACHE_FLUSH);
if (z->state != DNS_ZONE_ITEM_ESTABLISHED)
continue;
if (dns_resource_key_is_dnssd_ptr(z->rr->key))
flags = goodbye ? DNS_ANSWER_GOODBYE : 0;
else
flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH;
r = dns_answer_add(answer, z->rr, 0 , flags);
if (r < 0)
return log_debug_errno(r, "Failed to add PTR RR to answer: %m");
return log_debug_errno(r, "Failed to add RR to announce: %m");
}
/* Since all the active services are in the zone make them discoverable now. */
SET_FOREACH(service_type, types, iterator) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr;
rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
"_services._dns-sd._udp.local");
rr->ptr.name = strdup(service_type);
rr->ttl = MDNS_DEFAULT_TTL;
r = dns_zone_put(&scope->zone, scope, rr, false);
if (r < 0)
log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone: %m");
r = dns_answer_add(answer, rr, 0 , 0);
if (r < 0)
return log_debug_errno(r, "Failed to add RR to announce: %m");
}
if (dns_answer_isempty(answer))

17
src/resolve/resolved-dns-zone.c
View file

@ -680,3 +680,20 @@ bool dns_zone_is_empty(DnsZone *zone) {
return hashmap_isempty(zone->by_key);
}
bool dns_zone_contains_name(DnsZone *z, const char *name) {
DnsZoneItem *i, *first;
first = hashmap_get(z->by_name, name);
if (!first)
return false;
LIST_FOREACH(by_name, i, first) {
if (!IN_SET(i->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING))
continue;
return true;
}
return false;
}

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

@ -84,3 +84,4 @@ void dns_zone_item_probe_stop(DnsZoneItem *i);
void dns_zone_dump(DnsZone *zone, FILE *f);
bool dns_zone_is_empty(DnsZone *zone);
bool dns_zone_contains_name(DnsZone *z, const char *name);