resolved: also add a way to flush all caches via the bus

And expose it in "resolve-tool --flush-caches".

5 files changed, 67 insertions, 4 deletions

diff --git a/man/systemd-resolve.xml b/man/systemd-resolve.xml
index 4b66f836a2..b917ac20a2 100644
--- a/man/systemd-resolve.xml
+++ b/man/systemd-resolve.xml
@@ -288,6 +288,12 @@
         <listitem><para>Resets the statistics counters shown in <option>--statistics</option> to zero.</para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>--flush-caches</option></term>
+
+        <listitem><para>Flushes all DNS resource record caches the service maintains locally.</para></listitem>
+      </varlistentry>
+
       <xi:include href="standard-options.xml" xpointer="help" />
       <xi:include href="standard-options.xml" xpointer="version" />
     </variablelist>
diff --git a/src/resolve/resolve-tool.c b/src/resolve/resolve-tool.c
index 7e145c64c4..bc6dcf04a4 100644
--- a/src/resolve/resolve-tool.c
+++ b/src/resolve/resolve-tool.c
@@ -66,6 +66,7 @@ static enum {
         MODE_RESOLVE_TLSA,
         MODE_STATISTICS,
         MODE_RESET_STATISTICS,
+        MODE_FLUSH_CACHES,
 } arg_mode = MODE_RESOLVE_HOST;
 
 static ServiceFamily service_family_from_string(const char *s) {
@@ -1037,6 +1038,24 @@ static int reset_statistics(sd_bus *bus) {
         return 0;
 }
 
+static int flush_caches(sd_bus *bus) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        int r;
+
+        r = sd_bus_call_method(bus,
+                               "org.freedesktop.resolve1",
+                               "/org/freedesktop/resolve1",
+                               "org.freedesktop.resolve1.Manager",
+                               "FlushCaches",
+                               &error,
+                               NULL,
+                               NULL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to flush caches: %s", bus_error_message(&error, r));
+
+        return 0;
+}
+
 static void help_protocol_types(void) {
         if (arg_legend)
                 puts("Known protocol types:");
@@ -1097,6 +1116,7 @@ static void help(void) {
                "     --legend=BOOL          Print headers and additional info (default: yes)\n"
                "     --statistics           Show resolver statistics\n"
                "     --reset-statistics     Reset resolver statistics\n"
+               "     --flush-caches         Flush all local DNS caches\n"
                , program_invocation_short_name);
 }
 
@@ -1114,6 +1134,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_SEARCH,
                 ARG_STATISTICS,
                 ARG_RESET_STATISTICS,
+                ARG_FLUSH_CACHES,
         };
 
         static const struct option options[] = {
@@ -1134,6 +1155,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "search",           required_argument, NULL, ARG_SEARCH           },
                 { "statistics",       no_argument,       NULL, ARG_STATISTICS,      },
                 { "reset-statistics", no_argument,       NULL, ARG_RESET_STATISTICS },
+                { "flush-caches",     no_argument,       NULL, ARG_FLUSH_CACHES     },
                 {}
         };
 
@@ -1307,6 +1329,10 @@ static int parse_argv(int argc, char *argv[]) {
                         arg_mode = MODE_RESET_STATISTICS;
                         break;
 
+                case ARG_FLUSH_CACHES:
+                        arg_mode = MODE_FLUSH_CACHES;
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -1473,6 +1499,16 @@ int main(int argc, char **argv) {
 
                 r = reset_statistics(bus);
                 break;
+
+        case MODE_FLUSH_CACHES:
+                if (argc > optind) {
+                        log_error("Too many arguments.");
+                        r = -EINVAL;
+                        goto finish;
+                }
+
+                r = flush_caches(bus);
+                break;
         }
 
 finish:
diff --git a/src/resolve/resolved-bus.c b/src/resolve/resolved-bus.c
index 6d4e5746f7..a72a03cfad 100644
--- a/src/resolve/resolved-bus.c
+++ b/src/resolve/resolved-bus.c
@@ -1535,6 +1535,17 @@ static int bus_method_get_link(sd_bus_message *message, void *userdata, sd_bus_e
         return sd_bus_reply_method_return(message, "o", p);
 }
 
+static int bus_method_flush_caches(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        Manager *m = userdata;
+
+        assert(message);
+        assert(m);
+
+        manager_flush_caches(m);
+
+        return sd_bus_reply_method_return(message, NULL);
+}
+
 static const sd_bus_vtable resolve_vtable[] = {
         SD_BUS_VTABLE_START(0),
         SD_BUS_PROPERTY("LLMNRHostname", "s", NULL, offsetof(Manager, llmnr_hostname), 0),
@@ -1550,6 +1561,7 @@ static const sd_bus_vtable resolve_vtable[] = {
         SD_BUS_METHOD("ResolveRecord", "isqqt", "a(iqqay)t", bus_method_resolve_record, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("ResolveService", "isssit", "a(qqqsa(iiay)s)aayssst", bus_method_resolve_service, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("ResetStatistics", NULL, NULL, bus_method_reset_statistics, 0),
+        SD_BUS_METHOD("FlushCaches", NULL, NULL, bus_method_flush_caches, 0),
         SD_BUS_METHOD("GetLink", "i", "o", bus_method_get_link, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("SetLinkDNS", "ia(iay)", NULL, bus_method_set_link_dns_servers, 0),
         SD_BUS_METHOD("SetLinkDomains", "ia(sb)", NULL, bus_method_set_link_domains, 0),
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 6cf75f9183..a46f13b92f 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -468,16 +468,14 @@ static int manager_sigusr1(sd_event_source *s, const struct signalfd_siginfo *si
 
 static int manager_sigusr2(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
         Manager *m = userdata;
-        DnsScope *scope;
 
         assert(s);
         assert(si);
         assert(m);
 
-        LIST_FOREACH(scopes, scope, m->dns_scopes)
-                dns_cache_flush(&scope->cache);
-
+        manager_flush_caches(m);
         log_info("Flushed all caches.");
+
         return 0;
 }
 
@@ -1251,3 +1249,12 @@ bool manager_routable(Manager *m, int family) {
 
         return false;
 }
+
+void manager_flush_caches(Manager *m) {
+        DnsScope *scope;
+
+        assert(m);
+
+        LIST_FOREACH(scopes, scope, m->dns_scopes)
+                dns_cache_flush(&scope->cache);
+}
diff --git a/src/resolve/resolved-manager.h b/src/resolve/resolved-manager.h
index 97f75ace79..ef71202ef9 100644
--- a/src/resolve/resolved-manager.h
+++ b/src/resolve/resolved-manager.h
@@ -170,3 +170,5 @@ bool manager_dnssec_supported(Manager *m);
 void manager_dnssec_verdict(Manager *m, DnssecVerdict verdict, const DnsResourceKey *key);
 
 bool manager_routable(Manager *m, int family);
+
+void manager_flush_caches(Manager *m);