Merge pull request #955 from poettering/resolved-localhost-xyz
resolved: enable synthesizing of A, AAAA and PTR records for "localhost"
This commit is contained in:
Tom Gundersen
commit
0125ed22e3
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@ -19,6 +19,8 @@
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "hostname-util.h"
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#include "dns-domain.h"
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#include "resolved-dns-query.h"
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@ -212,6 +214,156 @@ static int dns_query_add_transaction_split(DnsQuery *q, DnsScope *s) {
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return 0;
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}
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static int SYNTHESIZE_IFINDEX(int ifindex) {
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/* When the caller asked for resolving on a specific interface,
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* we synthesize the answer for that interface. However, if
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* nothing specific was claimed, we synthesize the answer for
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* localhost. */
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if (ifindex > 0)
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return ifindex;
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return LOOPBACK_IFINDEX;
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}
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static int SYNTHESIZE_FAMILY(uint64_t flags) {
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/* Picks an address family depending on set flags. This is
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* purely for synthesized answers, where the family we return
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* for the reply should match what was requested in the
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* question, even though we are synthesizing the answer
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* here. */
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if (!(flags & SD_RESOLVED_DNS)) {
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if (flags & SD_RESOLVED_LLMNR_IPV4)
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return AF_INET;
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if (flags & SD_RESOLVED_LLMNR_IPV6)
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return AF_INET6;
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}
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return AF_UNSPEC;
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}
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static DnsProtocol SYNTHESIZE_PROTOCOL(uint64_t flags) {
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/* Similar as SYNTHESIZE_FAMILY() but does this for the
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* protocol. If resolving via DNS was requested, we claim it
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* was DNS. Similar, if nothing specific was
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* requested. However, if only resolving via LLMNR was
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* requested we return that. */
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if (flags & SD_RESOLVED_DNS)
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return DNS_PROTOCOL_DNS;
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if (flags & SD_RESOLVED_LLMNR)
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return DNS_PROTOCOL_LLMNR;
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return DNS_PROTOCOL_DNS;
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}
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static void dns_query_synthesize_reply(DnsQuery *q, DnsTransactionState *state) {
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_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
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unsigned i;
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int r;
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assert(q);
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assert(state);
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/* Tries to synthesize localhost RR replies where appropriate */
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if (!IN_SET(*state,
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DNS_TRANSACTION_FAILURE,
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DNS_TRANSACTION_NO_SERVERS,
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DNS_TRANSACTION_TIMEOUT,
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DNS_TRANSACTION_ATTEMPTS_MAX_REACHED))
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return;
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for (i = 0; i < q->question->n_keys; i++) {
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_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
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const char *name;
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if (q->question->keys[i]->class != DNS_CLASS_IN &&
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q->question->keys[i]->class != DNS_CLASS_ANY)
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continue;
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name = DNS_RESOURCE_KEY_NAME(q->question->keys[i]);
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if (is_localhost(name)) {
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switch (q->question->keys[i]->type) {
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case DNS_TYPE_A:
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case DNS_TYPE_ANY:
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rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_A, name);
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if (!rr) {
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log_oom();
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return;
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}
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rr->a.in_addr.s_addr = htobe32(INADDR_LOOPBACK);
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break;
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case DNS_TYPE_AAAA:
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rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_AAAA, name);
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if (!rr) {
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log_oom();
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return;
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}
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rr->aaaa.in6_addr = in6addr_loopback;
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break;
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}
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} else if (IN_SET(q->question->keys[i]->type, DNS_TYPE_PTR, DNS_TYPE_ANY) &&
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(dns_name_endswith(name, "127.in-addr.arpa") > 0 ||
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dns_name_equal(name, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0)) {
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rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, name);
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if (!rr) {
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log_oom();
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return;
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}
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rr->ptr.name = strdup("localhost");
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if (!rr->ptr.name) {
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log_oom();
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return;
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}
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}
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if (!rr)
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continue;
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if (!answer) {
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answer = dns_answer_new(q->question->n_keys);
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if (!answer) {
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log_oom();
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return;
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}
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}
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r = dns_answer_add(answer, rr);
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if (r < 0) {
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log_error_errno(r, "Failed to add synthetic RR to answer: %m");
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return;
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}
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}
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if (!answer)
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return;
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dns_answer_unref(q->answer);
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q->answer = answer;
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answer = NULL;
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q->answer_ifindex = SYNTHESIZE_IFINDEX(q->ifindex);
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q->answer_family = SYNTHESIZE_FAMILY(q->flags);
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q->answer_protocol = SYNTHESIZE_PROTOCOL(q->flags);
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q->answer_rcode = DNS_RCODE_SUCCESS;
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*state = DNS_TRANSACTION_SUCCESS;
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}
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int dns_query_go(DnsQuery *q) {
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DnsScopeMatch found = DNS_SCOPE_NO;
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DnsScope *s, *first = NULL;
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@ -253,8 +405,17 @@ int dns_query_go(DnsQuery *q) {
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}
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}
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if (found == DNS_SCOPE_NO)
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if (found == DNS_SCOPE_NO) {
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DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS;
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dns_query_synthesize_reply(q, &state);
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if (state != DNS_TRANSACTION_NO_SERVERS) {
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dns_query_complete(q, state);
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return 1;
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}
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return -ESRCH;
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}
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r = dns_query_add_transaction_split(q, first);
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if (r < 0)
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@ -428,6 +589,9 @@ void dns_query_ready(DnsQuery *q) {
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q->answer_family = scope ? scope->family : AF_UNSPEC;
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}
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/* Try to synthesize a reply if we couldn't resolve something. */
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dns_query_synthesize_reply(q, &state);
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dns_query_complete(q, state);
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}
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@ -325,10 +325,6 @@ DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, co
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if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family) & flags) == 0)
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return DNS_SCOPE_NO;
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STRV_FOREACH(i, s->domains)
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if (dns_name_endswith(domain, *i) > 0)
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return DNS_SCOPE_YES;
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if (dns_name_root(domain) != 0)
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return DNS_SCOPE_NO;
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@ -340,6 +336,10 @@ DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, co
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dns_name_equal(domain, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0)
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return DNS_SCOPE_NO;
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STRV_FOREACH(i, s->domains)
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if (dns_name_endswith(domain, *i) > 0)
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return DNS_SCOPE_YES;
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if (s->protocol == DNS_PROTOCOL_DNS) {
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if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
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dns_name_endswith(domain, "0.8.e.f.ip6.arpa") == 0 &&
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