/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2014 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include "list.h" #include "resolved-dns-zone.h" #include "resolved-dns-domain.h" #include "resolved-dns-packet.h" /* Never allow more than 1K entries */ #define ZONE_MAX 1024 void dns_zone_item_probe_stop(DnsZoneItem *i) { DnsTransaction *t; assert(i); if (!i->probe_transaction) return; t = i->probe_transaction; i->probe_transaction = NULL; set_remove(t->zone_items, i); dns_transaction_gc(t); } static void dns_zone_item_free(DnsZoneItem *i) { if (!i) return; dns_zone_item_probe_stop(i); dns_resource_record_unref(i->rr); free(i); } DEFINE_TRIVIAL_CLEANUP_FUNC(DnsZoneItem*, dns_zone_item_free); static void dns_zone_item_remove_and_free(DnsZone *z, DnsZoneItem *i) { DnsZoneItem *first; assert(z); if (!i) return; first = hashmap_get(z->by_key, i->rr->key); LIST_REMOVE(by_key, first, i); if (first) assert_se(hashmap_replace(z->by_key, first->rr->key, first) >= 0); else hashmap_remove(z->by_key, i->rr->key); first = hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(i->rr->key)); LIST_REMOVE(by_name, first, i); if (first) assert_se(hashmap_replace(z->by_name, DNS_RESOURCE_KEY_NAME(first->rr->key), first) >= 0); else hashmap_remove(z->by_name, DNS_RESOURCE_KEY_NAME(i->rr->key)); dns_zone_item_free(i); } void dns_zone_flush(DnsZone *z) { DnsZoneItem *i; assert(z); while ((i = hashmap_first(z->by_key))) dns_zone_item_remove_and_free(z, i); assert(hashmap_size(z->by_key) == 0); assert(hashmap_size(z->by_name) == 0); hashmap_free(z->by_key); z->by_key = NULL; hashmap_free(z->by_name); z->by_name = NULL; } static DnsZoneItem* dns_zone_get(DnsZone *z, DnsResourceRecord *rr) { DnsZoneItem *i; assert(z); assert(rr); LIST_FOREACH(by_key, i, hashmap_get(z->by_key, rr->key)) if (dns_resource_record_equal(i->rr, rr) > 0) return i; return NULL; } void dns_zone_remove_rr(DnsZone *z, DnsResourceRecord *rr) { DnsZoneItem *i; assert(z); assert(rr); i = dns_zone_get(z, rr); if (i) dns_zone_item_remove_and_free(z, i); } static int dns_zone_init(DnsZone *z) { int r; assert(z); r = hashmap_ensure_allocated(&z->by_key, &dns_resource_key_hash_ops); if (r < 0) return r; r = hashmap_ensure_allocated(&z->by_name, &dns_name_hash_ops); if (r < 0) return r; return 0; } static int dns_zone_link_item(DnsZone *z, DnsZoneItem *i) { DnsZoneItem *first; int r; first = hashmap_get(z->by_key, i->rr->key); if (first) { LIST_PREPEND(by_key, first, i); assert_se(hashmap_replace(z->by_key, first->rr->key, first) >= 0); } else { r = hashmap_put(z->by_key, i->rr->key, i); if (r < 0) return r; } first = hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(i->rr->key)); if (first) { LIST_PREPEND(by_name, first, i); assert_se(hashmap_replace(z->by_name, DNS_RESOURCE_KEY_NAME(first->rr->key), first) >= 0); } else { r = hashmap_put(z->by_name, DNS_RESOURCE_KEY_NAME(i->rr->key), i); if (r < 0) return r; } return 0; } static int dns_zone_item_probe_start(DnsZoneItem *i) { _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL; DnsTransaction *t; int r; assert(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; question = dns_question_new(1); if (!question) return -ENOMEM; r = dns_question_add(question, key); if (r < 0) return r; t = dns_scope_find_transaction(i->scope, question, false); if (!t) { r = dns_transaction_new(&t, i->scope, question); if (r < 0) return r; } r = set_ensure_allocated(&t->zone_items, NULL); if (r < 0) goto gc; r = set_put(t->zone_items, i); if (r < 0) goto gc; i->probe_transaction = t; if (t->state == DNS_TRANSACTION_NULL) { i->block_ready++; r = dns_transaction_go(t); i->block_ready--; if (r < 0) { dns_zone_item_probe_stop(i); return r; } } dns_zone_item_ready(i); return 0; gc: dns_transaction_gc(t); return r; } int dns_zone_put(DnsZone *z, DnsScope *s, DnsResourceRecord *rr, bool probe) { _cleanup_(dns_zone_item_freep) DnsZoneItem *i = NULL; DnsZoneItem *existing; int r; assert(z); assert(s); assert(rr); if (rr->key->class == DNS_CLASS_ANY) return -EINVAL; if (rr->key->type == DNS_TYPE_ANY) return -EINVAL; existing = dns_zone_get(z, rr); if (existing) return 0; r = dns_zone_init(z); if (r < 0) return r; i = new0(DnsZoneItem, 1); if (!i) return -ENOMEM; i->scope = s; i->rr = dns_resource_record_ref(rr); i->probing_enabled = probe; r = dns_zone_link_item(z, i); if (r < 0) return r; if (probe) { DnsZoneItem *first, *j; bool established = false; /* Check if there's already an RR with the same name * established. If so, it has been probed already, and * we don't ned to probe again. */ LIST_FIND_HEAD(by_name, i, first); LIST_FOREACH(by_name, j, first) { if (i == j) continue; if (j->state == DNS_ZONE_ITEM_ESTABLISHED) established = true; } if (established) i->state = DNS_ZONE_ITEM_ESTABLISHED; else { i->state = DNS_ZONE_ITEM_PROBING; r = dns_zone_item_probe_start(i); if (r < 0) { dns_zone_item_remove_and_free(z, i); i = NULL; return r; } } } else i->state = DNS_ZONE_ITEM_ESTABLISHED; i = NULL; return 0; } int dns_zone_lookup(DnsZone *z, DnsQuestion *q, DnsAnswer **ret_answer, DnsAnswer **ret_soa, bool *ret_tentative) { _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL; unsigned i, n_answer = 0, n_soa = 0; bool tentative = true; int r; assert(z); assert(q); assert(ret_answer); assert(ret_soa); if (q->n_keys <= 0) { *ret_answer = NULL; *ret_soa = NULL; if (ret_tentative) *ret_tentative = false; return 0; } /* First iteration, count what we have */ for (i = 0; i < q->n_keys; i++) { DnsZoneItem *j, *first; if (q->keys[i]->type == DNS_TYPE_ANY || q->keys[i]->class == DNS_CLASS_ANY) { bool found = false, added = false; int k; /* If this is a generic match, then we have to * go through the list by the name and look * for everything manually */ first = hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(q->keys[i])); LIST_FOREACH(by_name, j, first) { if (!IN_SET(j->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING)) continue; found = true; k = dns_resource_key_match_rr(q->keys[i], j->rr); if (k < 0) return k; if (k > 0) { n_answer++; added = true; } } if (found && !added) n_soa++; } else { bool found = false; /* If this is a specific match, then look for * the right key immediately */ first = hashmap_get(z->by_key, q->keys[i]); LIST_FOREACH(by_key, j, first) { if (!IN_SET(j->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING)) continue; found = true; n_answer++; } if (!found) { first = hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(q->keys[i])); LIST_FOREACH(by_name, j, first) { if (!IN_SET(j->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING)) continue; n_soa++; break; } } } } if (n_answer <= 0 && n_soa <= 0) { *ret_answer = NULL; *ret_soa = NULL; if (ret_tentative) *ret_tentative = false; return 0; } 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, *first; if (q->keys[i]->type == DNS_TYPE_ANY || q->keys[i]->class == DNS_CLASS_ANY) { bool found = false, added = false; int k; first = hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(q->keys[i])); LIST_FOREACH(by_name, j, first) { if (!IN_SET(j->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING)) continue; found = true; if (j->state != DNS_ZONE_ITEM_PROBING) tentative = false; k = dns_resource_key_match_rr(q->keys[i], j->rr); if (k < 0) return k; if (k > 0) { r = dns_answer_add(answer, j->rr); if (r < 0) return r; added = true; } } if (found && !added) { r = dns_answer_add_soa(soa, DNS_RESOURCE_KEY_NAME(q->keys[i]), LLMNR_DEFAULT_TTL); if (r < 0) return r; } } else { bool found = false; first = hashmap_get(z->by_key, q->keys[i]); LIST_FOREACH(by_key, j, first) { if (!IN_SET(j->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING)) continue; found = true; if (j->state != DNS_ZONE_ITEM_PROBING) tentative = false; r = dns_answer_add(answer, j->rr); if (r < 0) return r; } if (!found) { bool add_soa = false; first = hashmap_get(z->by_name, DNS_RESOURCE_KEY_NAME(q->keys[i])); LIST_FOREACH(by_name, j, first) { if (!IN_SET(j->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING)) continue; if (j->state != DNS_ZONE_ITEM_PROBING) tentative = false; add_soa = true; } if (add_soa) { r = dns_answer_add_soa(soa, DNS_RESOURCE_KEY_NAME(q->keys[i]), LLMNR_DEFAULT_TTL); if (r < 0) return r; } } } } *ret_answer = answer; answer = NULL; *ret_soa = soa; soa = NULL; if (ret_tentative) *ret_tentative = tentative; return 1; } void dns_zone_item_conflict(DnsZoneItem *i) { _cleanup_free_ char *pretty = NULL; assert(i); if (!IN_SET(i->state, DNS_ZONE_ITEM_PROBING, DNS_ZONE_ITEM_VERIFYING, DNS_ZONE_ITEM_ESTABLISHED)) return; dns_resource_record_to_string(i->rr, &pretty); log_info("Detected conflict on %s", strna(pretty)); dns_zone_item_probe_stop(i); /* Withdraw the conflict item */ i->state = DNS_ZONE_ITEM_WITHDRAWN; /* Maybe change the hostname */ if (dns_name_equal(i->scope->manager->hostname, DNS_RESOURCE_KEY_NAME(i->rr->key)) > 0) manager_next_hostname(i->scope->manager); } void dns_zone_item_ready(DnsZoneItem *i) { _cleanup_free_ char *pretty = NULL; assert(i); assert(i->probe_transaction); if (i->block_ready > 0) return; if (IN_SET(i->probe_transaction->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING)) return; if (i->probe_transaction->state == DNS_TRANSACTION_SUCCESS) { bool we_lost = false; /* The probe got a successful reply. If we so far * weren't established we just give up. If we already * were established, and the peer has the * lexicographically larger IP address we continue * and defend it. */ if (!IN_SET(i->state, DNS_ZONE_ITEM_ESTABLISHED, DNS_ZONE_ITEM_VERIFYING)) { log_debug("Got a successful probe for not yet established RR, we lost."); we_lost = true; } else { assert(i->probe_transaction->received); we_lost = memcmp(&i->probe_transaction->received->sender, &i->probe_transaction->received->destination, FAMILY_ADDRESS_SIZE(i->probe_transaction->received->family)) < 0; if (we_lost) log_debug("Got a successful probe reply for an established RR, and we have a lexicographically larger IP address and thus lost."); } if (we_lost) { dns_zone_item_conflict(i); return; } log_debug("Got a successful probe reply, but peer has lexicographically lower IP address and thus lost."); } dns_resource_record_to_string(i->rr, &pretty); log_debug("Record %s successfully probed.", strna(pretty)); dns_zone_item_probe_stop(i); i->state = DNS_ZONE_ITEM_ESTABLISHED; } static int dns_zone_item_verify(DnsZoneItem *i) { _cleanup_free_ char *pretty = NULL; int r; assert(i); if (i->state != DNS_ZONE_ITEM_ESTABLISHED) return 0; dns_resource_record_to_string(i->rr, &pretty); log_debug("Verifying RR %s", strna(pretty)); i->state = DNS_ZONE_ITEM_VERIFYING; r = dns_zone_item_probe_start(i); if (r < 0) { log_error_errno(r, "Failed to start probing for verifying RR: %m"); i->state = DNS_ZONE_ITEM_ESTABLISHED; return r; } return 0; } int dns_zone_check_conflicts(DnsZone *zone, DnsResourceRecord *rr) { DnsZoneItem *i, *first; int c = 0; assert(zone); assert(rr); /* This checks whether a response RR we received from somebody * else is one that we actually thought was uniquely ours. If * so, we'll verify our RRs. */ /* No conflict if we don't have the name at all. */ first = hashmap_get(zone->by_name, DNS_RESOURCE_KEY_NAME(rr->key)); if (!first) return 0; /* No conflict if we have the exact same RR */ if (dns_zone_get(zone, rr)) return 0; /* OK, somebody else has RRs for the same name. Yuck! Let's * start probing again */ LIST_FOREACH(by_name, i, first) { if (dns_resource_record_equal(i->rr, rr)) continue; dns_zone_item_verify(i); c++; } return c; } int dns_zone_verify_conflicts(DnsZone *zone, DnsResourceKey *key) { DnsZoneItem *i, *first; int c = 0; assert(zone); /* Somebody else notified us about a possible conflict. Let's * verify if that's true. */ first = hashmap_get(zone->by_name, DNS_RESOURCE_KEY_NAME(key)); if (!first) return 0; LIST_FOREACH(by_name, i, first) { dns_zone_item_verify(i); c++; } return c; } void dns_zone_verify_all(DnsZone *zone) { DnsZoneItem *i; Iterator iterator; assert(zone); HASHMAP_FOREACH(i, zone->by_key, iterator) { DnsZoneItem *j; LIST_FOREACH(by_key, j, i) dns_zone_item_verify(j); } }