static void dns_transaction_next_dns_server(DnsTransaction *t) {
assert(t);
t->server = dns_server_unref(t->server);
t->dns_udp_event_source = sd_event_source_unref(t->dns_udp_event_source);
t->dns_udp_fd = safe_close(t->dns_udp_fd);
dns_scope_next_dns_server(t->scope);
}
DnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
assert(m);
if (m->current_dns_server == s)
return s;
if (s)
log_debug("Switching to %s DNS server %s.",
dns_server_type_to_string(s->type),
dns_server_string(s));
dns_server_unref(m->current_dns_server);
m->current_dns_server = dns_server_ref(s);
if (m->unicast_scope)
dns_cache_flush(&m->unicast_scope->cache);
return s;
}
void dns_server_unlink(DnsServer *s) {
assert(s);
assert(s->manager);
/* This removes the specified server from the linked list of
* servers, but any server might still stay around if it has
* refs, for example from an ongoing transaction. */
if (!s->linked)
return;
switch (s->type) {
case DNS_SERVER_LINK:
assert(s->link);
assert(s->link->n_dns_servers > 0);
LIST_REMOVE(servers, s->link->dns_servers, s);
s->link->n_dns_servers--;
break;
case DNS_SERVER_SYSTEM:
assert(s->manager->n_dns_servers > 0);
LIST_REMOVE(servers, s->manager->dns_servers, s);
s->manager->n_dns_servers--;
break;
case DNS_SERVER_FALLBACK:
assert(s->manager->n_dns_servers > 0);
LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);
s->manager->n_dns_servers--;
break;
}
s->linked = false;
if (s->link && s->link->current_dns_server == s)
link_set_dns_server(s->link, NULL);
if (s->manager->current_dns_server == s)
manager_set_dns_server(s->manager, NULL);
dns_server_unref(s);
}
DnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
assert(m);
if (m->current_dns_server == s)
return s;
if (s) {
_cleanup_free_ char *ip = NULL;
in_addr_to_string(s->family, &s->address, &ip);
log_info("Switching to system DNS server %s.", strna(ip));
}
dns_server_unref(m->current_dns_server);
m->current_dns_server = dns_server_ref(s);
if (m->unicast_scope)
dns_cache_flush(&m->unicast_scope->cache);
return s;
}
DnsTransaction* dns_transaction_free(DnsTransaction *t) {
DnsQuery *q;
DnsZoneItem *i;
if (!t)
return NULL;
sd_event_source_unref(t->timeout_event_source);
dns_packet_unref(t->sent);
dns_packet_unref(t->received);
dns_answer_unref(t->cached);
sd_event_source_unref(t->dns_udp_event_source);
safe_close(t->dns_udp_fd);
dns_server_unref(t->server);
dns_stream_free(t->stream);
if (t->scope) {
hashmap_remove(t->scope->transactions, t->key);
if (t->id != 0)
hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id));
}
dns_resource_key_unref(t->key);
while ((q = set_steal_first(t->queries)))
set_remove(q->transactions, t);
set_free(t->queries);
while ((i = set_steal_first(t->zone_items)))
i->probe_transaction = NULL;
set_free(t->zone_items);
free(t);
return NULL;
}
static int dns_transaction_open_tcp(DnsTransaction *t) {
DnsServer *server = NULL;
_cleanup_close_ int fd = -1;
int r;
assert(t);
if (t->stream)
return 0;
switch (t->scope->protocol) {
case DNS_PROTOCOL_DNS:
fd = dns_scope_tcp_socket(t->scope, AF_UNSPEC, NULL, 53, &server);
break;
case DNS_PROTOCOL_LLMNR:
/* When we already received a reply to this (but it was truncated), send to its sender address */
if (t->received)
fd = dns_scope_tcp_socket(t->scope, t->received->family, &t->received->sender, t->received->sender_port, NULL);
else {
union in_addr_union address;
int family = AF_UNSPEC;
/* Otherwise, try to talk to the owner of a
* the IP address, in case this is a reverse
* PTR lookup */
r = dns_name_address(DNS_RESOURCE_KEY_NAME(t->key), &family, &address);
if (r < 0)
return r;
if (r == 0)
return -EINVAL;
if (family != t->scope->family)
return -ESRCH;
fd = dns_scope_tcp_socket(t->scope, family, &address, LLMNR_PORT, NULL);
}
break;
default:
return -EAFNOSUPPORT;
}
if (fd < 0)
return fd;
r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd);
if (r < 0)
return r;
fd = -1;
r = dns_stream_write_packet(t->stream, t->sent);
if (r < 0) {
t->stream = dns_stream_free(t->stream);
return r;
}
dns_server_unref(t->server);
t->server = dns_server_ref(server);
t->received = dns_packet_unref(t->received);
t->stream->complete = on_stream_complete;
t->stream->transaction = t;
/* The interface index is difficult to determine if we are
* connecting to the local host, hence fill this in right away
* instead of determining it from the socket */
if (t->scope->link)
t->stream->ifindex = t->scope->link->ifindex;
return 0;
}
