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resolvectl: add resolvectl command for dumping cache contents

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A wrapper around the new varlink call, showing the data either in its
native JSON or in a more human readable textual form.
This commit is contained in:
Lennart Poettering 2023-06-12 16:46:04 +02:00
parent 25165c1dea
commit 6050e8b550
2 changed files with 160 additions and 0 deletions
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7
man/resolvectl.xml
View file

@ -212,6 +212,13 @@
output.</para></listitem>
</varlistentry>
<varlistentry>
<term><command>show-cache</command></term>
<listitem><para>Show current cache content, per scope. Use <option>--json=</option> to enable JSON
output.</para></listitem>
</varlistentry>
<xi:include href="systemctl.xml" xpointer="log-level" />
</variablelist>
</refsect1>

153
src/resolve/resolvectl.c
View file

@ -2779,6 +2779,157 @@ static int verb_monitor(int argc, char *argv[], void *userdata) {
return c;
}
static int dump_cache_item(JsonVariant *item) {
struct item_info {
JsonVariant *key;
JsonVariant *rrs;
const char *type;
uint64_t until;
} item_info = {};
static const JsonDispatch dispatch_table[] = {
{ "key", JSON_VARIANT_OBJECT, json_dispatch_variant_noref, offsetof(struct item_info, key), JSON_MANDATORY },
{ "rrs", JSON_VARIANT_ARRAY, json_dispatch_variant_noref, offsetof(struct item_info, rrs), 0 },
{ "type", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(struct item_info, type), 0 },
{ "until", JSON_VARIANT_UNSIGNED, json_dispatch_uint64, offsetof(struct item_info, until), 0 },
{},
};
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *k = NULL;
int r, c = 0;
r = json_dispatch(item, dispatch_table, NULL, JSON_LOG, &item_info);
if (r < 0)
return r;
r = dns_resource_key_from_json(item_info.key, &k);
if (r < 0)
return log_error_errno(r, "Failed to turn JSON data to resource key: %m");
if (item_info.type)
printf("%s %s%s%s\n", DNS_RESOURCE_KEY_TO_STRING(k), ansi_highlight_red(), item_info.type, ansi_normal());
else {
JsonVariant *i;
JSON_VARIANT_ARRAY_FOREACH(i, item_info.rrs) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
_cleanup_free_ void *data = NULL;
JsonVariant *raw;
size_t size;
raw = json_variant_by_key(i, "raw");
if (!raw)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "raw field missing from RR JSON data.");
r = json_variant_unbase64(raw, &data, &size);
if (r < 0)
return log_error_errno(r, "Unable to decode raw RR JSON data: %m");
r = dns_resource_record_new_from_raw(&rr, data, size);
if (r < 0)
return log_error_errno(r, "Failed to parse DNS data: %m");
printf("%s\n", dns_resource_record_to_string(rr));
c++;
}
}
return c;
}
static int dump_cache_scope(JsonVariant *scope) {
struct scope_info {
const char *protocol;
int family;
int ifindex;
const char *ifname;
JsonVariant *cache;
} scope_info = {
.family = AF_UNSPEC,
};
JsonVariant *i;
int r, c = 0;
static const JsonDispatch dispatch_table[] = {
{ "protocol", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(struct scope_info, protocol), JSON_MANDATORY },
{ "family", JSON_VARIANT_INTEGER, json_dispatch_int, offsetof(struct scope_info, family), 0 },
{ "ifindex", JSON_VARIANT_INTEGER, json_dispatch_int, offsetof(struct scope_info, ifindex), 0 },
{ "ifname", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(struct scope_info, ifname), 0 },
{ "cache", JSON_VARIANT_ARRAY, json_dispatch_variant_noref, offsetof(struct scope_info, cache), JSON_MANDATORY },
{},
};
r = json_dispatch(scope, dispatch_table, NULL, JSON_LOG, &scope_info);
if (r < 0)
return r;
printf("%sScope protocol=%s", ansi_underline(), scope_info.protocol);
if (scope_info.family != AF_UNSPEC)
printf(" family=%s", af_to_name(scope_info.family));
if (scope_info.ifindex > 0)
printf(" ifindex=%i", scope_info.ifindex);
if (scope_info.ifname)
printf(" ifname=%s", scope_info.ifname);
printf("%s\n", ansi_normal());
JSON_VARIANT_ARRAY_FOREACH(i, scope_info.cache) {
r = dump_cache_item(i);
if (r < 0)
return r;
c += r;
}
if (c == 0)
printf("%sNo entries.%s\n\n", ansi_grey(), ansi_normal());
else
printf("\n");
return 0;
}
static int verb_show_cache(int argc, char *argv[], void *userdata) {
_cleanup_(json_variant_unrefp) JsonVariant *d = NULL, *reply = NULL;
_cleanup_(varlink_unrefp) Varlink *vl = NULL;
int r;
r = varlink_connect_address(&vl, "/run/systemd/resolve/io.systemd.Resolve.Monitor");
if (r < 0)
return log_error_errno(r, "Failed to connect to query monitoring service /run/systemd/resolve/io.systemd.Resolve.Monitor: %m");
r = varlink_call(vl, "io.systemd.Resolve.Monitor.DumpCache", NULL, &reply, NULL, 0);
if (r < 0)
return log_error_errno(r, "Failed to issue DumpCache() varlink call: %m");
d = json_variant_by_key(reply, "dump");
if (!d)
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
"DumpCache() response is missing 'dump' key.");
if (!json_variant_is_array(d))
return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
"DumpCache() response 'dump' field not an array");
if (FLAGS_SET(arg_json_format_flags, JSON_FORMAT_OFF)) {
JsonVariant *i;
JSON_VARIANT_ARRAY_FOREACH(i, d) {
r = dump_cache_scope(i);
if (r < 0)
return r;
}
return 0;
}
return json_variant_dump(d, arg_json_format_flags, NULL, NULL);
}
static void help_protocol_types(void) {
if (arg_legend)
puts("Known protocol types:");
@ -2885,6 +3036,7 @@ static int native_help(void) {
" flush-caches Flush all local DNS caches\n"
" reset-server-features Forget learnt DNS server feature levels\n"
" monitor Monitor DNS queries\n"
" show-cache Show cache contents\n"
" dns [LINK [SERVER...]] Get/set per-interface DNS server address\n"
" domain [LINK [DOMAIN...]] Get/set per-interface search domain\n"
" default-route [LINK [BOOL]] Get/set per-interface default route flag\n"
@ -3531,6 +3683,7 @@ static int native_main(int argc, char *argv[], sd_bus *bus) {
{ "revert", VERB_ANY, 2, 0, verb_revert_link },
{ "log-level", VERB_ANY, 2, 0, verb_log_level },
{ "monitor", VERB_ANY, 1, 0, verb_monitor },
{ "show-cache", VERB_ANY, 1, 0, verb_show_cache },
{}
};