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resolved: add an option to control the DNS stub listener

This commit is contained in:
David Michael 2016-08-31 15:34:29 -07:00
parent 07f264e40a
commit 1ae4329575
8 changed files with 63 additions and 16 deletions
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12
man/resolved.conf.xml
View File

@ -213,6 +213,18 @@
(such as 127.0.0.1 or ::1), in order to avoid duplicate local caching.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>DNSStubListener=</varname></term>
<listitem><para>Takes a boolean argument or one of <literal>udp</literal> and <literal>tcp</literal>. If
<literal>udp</literal> (the default), a DNS stub resolver will listen for UDP requests on address 127.0.0.53
port 53. If <literal>tcp</literal>, the stub will listen for TCP requests on the same address and port. If
<literal>yes</literal>, the stub listens for both UDP and TCP requests. If <literal>no</literal>, the stub
listener is disabled.</para>
<para>Note that the DNS stub listener is turned off implicitly when its listening address and port are already
in use.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>

11
src/resolve/resolved-conf.c
View File

@ -23,8 +23,19 @@
#include "extract-word.h"
#include "parse-util.h"
#include "resolved-conf.h"
#include "string-table.h"
#include "string-util.h"
DEFINE_CONFIG_PARSE_ENUM(config_parse_dns_stub_listener_mode, dns_stub_listener_mode, DnsStubListenerMode, "Failed to parse DNS stub listener mode setting");
static const char* const dns_stub_listener_mode_table[_DNS_STUB_LISTENER_MODE_MAX] = {
[DNS_STUB_LISTENER_NO] = "no",
[DNS_STUB_LISTENER_UDP] = "udp",
[DNS_STUB_LISTENER_TCP] = "tcp",
[DNS_STUB_LISTENER_YES] = "yes",
};
DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(dns_stub_listener_mode, DnsStubListenerMode, DNS_STUB_LISTENER_YES);
int manager_add_dns_server_by_string(Manager *m, DnsServerType type, const char *word) {
union in_addr_union address;
int family, r, ifindex = 0;

15
src/resolve/resolved-conf.h
View File

@ -19,6 +19,17 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
typedef enum DnsStubListenerMode DnsStubListenerMode;
enum DnsStubListenerMode {
DNS_STUB_LISTENER_NO,
DNS_STUB_LISTENER_UDP,
DNS_STUB_LISTENER_TCP,
DNS_STUB_LISTENER_YES,
_DNS_STUB_LISTENER_MODE_MAX,
_DNS_STUB_LISTENER_MODE_INVALID = -1
};
#include "resolved-manager.h"
#include "resolved-dns-server.h"
@ -34,3 +45,7 @@ const struct ConfigPerfItem* resolved_gperf_lookup(const char *key, unsigned len
int config_parse_dns_servers(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
int config_parse_search_domains(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
int config_parse_dns_stub_listener_mode(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
const char* dns_stub_listener_mode_to_string(DnsStubListenerMode p) _const_;
DnsStubListenerMode dns_stub_listener_mode_from_string(const char *s) _pure_;

24
src/resolve/resolved-dns-stub.c
View File

@ -540,17 +540,21 @@ int manager_dns_stub_start(Manager *m) {
assert(m);
r = manager_dns_stub_udp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_UDP)) {
r = manager_dns_stub_udp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
}
r = manager_dns_stub_tcp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_TCP)) {
r = manager_dns_stub_tcp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
}
return 0;

13
src/resolve/resolved-gperf.gperf
View File

@ -14,9 +14,10 @@ struct ConfigPerfItem;
%struct-type
%includes
%%
Resolve.DNS, config_parse_dns_servers, DNS_SERVER_SYSTEM, 0
Resolve.FallbackDNS, config_parse_dns_servers, DNS_SERVER_FALLBACK, 0
Resolve.Domains, config_parse_search_domains, 0, 0
Resolve.LLMNR, config_parse_resolve_support, 0, offsetof(Manager, llmnr_support)
Resolve.DNSSEC, config_parse_dnssec_mode, 0, offsetof(Manager, dnssec_mode)
Resolve.Cache, config_parse_bool, 0, offsetof(Manager, enable_cache)
Resolve.DNS, config_parse_dns_servers, DNS_SERVER_SYSTEM, 0
Resolve.FallbackDNS, config_parse_dns_servers, DNS_SERVER_FALLBACK, 0
Resolve.Domains, config_parse_search_domains, 0, 0
Resolve.LLMNR, config_parse_resolve_support, 0, offsetof(Manager, llmnr_support)
Resolve.DNSSEC, config_parse_dnssec_mode, 0, offsetof(Manager, dnssec_mode)
Resolve.Cache, config_parse_bool, 0, offsetof(Manager, enable_cache)
Resolve.DNSStubListener, config_parse_dns_stub_listener_mode, 0, offsetof(Manager, dns_stub_listener_mode)

1
src/resolve/resolved-manager.c
View File

@ -501,6 +501,7 @@ int manager_new(Manager **ret) {
m->mdns_support = RESOLVE_SUPPORT_NO;
m->dnssec_mode = DEFAULT_DNSSEC_MODE;
m->enable_cache = true;
m->dns_stub_listener_mode = DNS_STUB_LISTENER_UDP;
m->read_resolv_conf = true;
m->need_builtin_fallbacks = true;
m->etc_hosts_last = m->etc_hosts_mtime = USEC_INFINITY;

2
src/resolve/resolved-manager.h
View File

@ -30,6 +30,7 @@
typedef struct Manager Manager;
#include "resolved-conf.h"
#include "resolved-dns-query.h"
#include "resolved-dns-search-domain.h"
#include "resolved-dns-server.h"
@ -47,6 +48,7 @@ struct Manager {
ResolveSupport mdns_support;
DnssecMode dnssec_mode;
bool enable_cache;
DnsStubListenerMode dns_stub_listener_mode;
/* Network */
Hashmap *links;

1
src/resolve/resolved.conf.in
View File

@ -18,3 +18,4 @@
#LLMNR=yes
#DNSSEC=@DEFAULT_DNSSEC_MODE@
#Cache=yes
#DNSStubListener=udp