man/org.freedesktop.resolve1.xml

@@ -115,6 +115,7 @@ node /org/freedesktop/resolve1 {
       ResetStatistics();
       FlushCaches();
       ResetServerFeatures();
+      GetMulticastHosts(out a(stiiay) UNNAMED);
     properties:
       readonly s LLMNRHostname = '...';
       @org.freedesktop.DBus.Property.EmitsChangedSignal("false")
@@ -164,6 +165,8 @@ node /org/freedesktop/resolve1 {
 
     <!--method ResetServerFeatures is not documented!-->
 
+    <!--method GetMulticastHosts is not documented!-->
+
     <!--property DNSSECNegativeTrustAnchors is not documented!-->
 
     <!--Autogenerated cross-references for systemd.directives, do not edit-->
@@ -212,6 +215,8 @@ node /org/freedesktop/resolve1 {
 
     <variablelist class="dbus-method" generated="True" extra-ref="ResetServerFeatures()"/>
 
+    <variablelist class="dbus-method" generated="True" extra-ref="GetMulticastHosts()"/>
+
     <variablelist class="dbus-property" generated="True" extra-ref="LLMNRHostname"/>
 
     <variablelist class="dbus-property" generated="True" extra-ref="LLMNR"/>

man/resolvectl.xml

@@ -180,6 +180,13 @@
         automatically, an explicit reverting is not necessary in that case.</para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><command>show-multicast</command></term>
+
+        <listitem><para>Display the discovered LLMNR and mDNS hostnames along with their IPv4/IPv6 addresses.
+        </para></listitem>
+      </varlistentry>
+
       <xi:include href="systemctl.xml" xpointer="log-level" />
     </variablelist>
   </refsect1>

mkosi.postinst

@@ -0,0 +1,5 @@
+#!/bin/sh
+set -e
+
+mkdir -p /root/build
+echo "directory /root/build" > ~/.gdbinit

src/basic/fs-util.c

@@ -1656,37 +1656,23 @@ int conservative_renameat(
                 goto do_rename;
 
         for (;;) {
-                uint8_t buf1[16*1024];
+                char buf1[16*1024];
-                uint8_t buf2[sizeof(buf1)];
+                char buf2[sizeof(buf1) + 1];
                 ssize_t l1, l2;
 
                 l1 = read(old_fd, buf1, sizeof(buf1));
                 if (l1 < 0)
                         goto do_rename;
 
-                if (l1 == sizeof(buf1))
-                        /* Read the full block, hence read a full block in the other file too */
-
-                        l2 = read(new_fd, buf2, l1);
-                else {
-                        assert((size_t) l1 < sizeof(buf1));
-
-                        /* Short read. This hence was the last block in the first file, and then came
-                         * EOF. Read one byte more in the second file, so that we can verify we hit EOF there
-                         * too. */
-
-                        assert((size_t) (l1 + 1) <= sizeof(buf2));
                 l2 = read(new_fd, buf2, l1 + 1);
-                }
+                if (l1 != l2)
-                if (l2 != l1)
                         goto do_rename;
 
+                if (l1 == 0) /* EOF on both! And everything's the same so far, yay! */
+                        break;
+
                 if (memcmp(buf1, buf2, l1) != 0)
                         goto do_rename;
-
-                if ((size_t) l1 < sizeof(buf1)) /* We hit EOF on the first file, and the second file too, hence exit
-                                                 * now. */
-                        break;
         }
 
 is_same:

src/resolve/resolvectl.c

@@ -2500,6 +2500,90 @@ static int verb_log_level(int argc, char *argv[], void *userdata) {
         return 0;
 }
 
+static const char *resolve_flags_to_string(uint64_t flags) {
+        return flags & SD_RESOLVED_DNS         ? "DNS" :
+                flags & SD_RESOLVED_LLMNR_IPV4 ? "LLMNR/IPv4" :
+                flags & SD_RESOLVED_LLMNR_IPV6 ? "LLMNR/IPv6" :
+                flags & SD_RESOLVED_MDNS_IPV4  ? "mDNS/IPv4" :
+                flags & SD_RESOLVED_MDNS_IPV6  ? "mDNS/IPv6" :
+                                                 "";
+}
+
+static int verb_show_multicast(int argc, char *argv[], void *userdata) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        _cleanup_(table_unrefp) Table *table = NULL;
+        sd_bus *bus = userdata;
+        int r;
+
+        assert(bus);
+
+        table = table_new("Hostname", "Address", "Source");
+        if (!table)
+                return log_oom();
+
+        r = bus_call_method(bus, bus_resolve_mgr, "GetMulticastHosts", &error, &reply, NULL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to query systemd-resolved: %s", bus_error_message(&error, r));
+
+        r = sd_bus_message_enter_container(reply, 'a', "(stiiay)");
+        if (r < 0)
+                return bus_log_parse_error(r);
+
+        while ((r = sd_bus_message_enter_container(reply, 'r', "stiiay")) > 0) {
+                char *canonical;
+                uint64_t flags;
+                _cleanup_free_ char *pretty = NULL;
+                int ifindex, family;
+                union in_addr_union a;
+
+                r = sd_bus_message_read(reply, "st", &canonical, &flags);
+                if (r < 0)
+                        return bus_log_parse_error(r);
+
+                r = sd_bus_message_read(reply, "i", &ifindex);
+                if (r < 0)
+                        return bus_log_parse_error(r);
+
+                sd_bus_error_free(&error);
+                r = bus_message_read_in_addr_auto(reply, &error, &family, &a);
+                if (r < 0)
+                        return log_error_errno(
+                                r,
+                                "systemd-resolved returned invalid result: %s",
+                                bus_error_message(&error, r));
+
+                r = sd_bus_message_exit_container(reply);
+                if (r < 0)
+                        return bus_log_parse_error(r);
+
+                r = in_addr_ifindex_to_string(family, &a, ifindex, &pretty);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to print address: %m");
+
+                r = table_add_many(
+                        table,
+                        TABLE_STRING,
+                        canonical,
+                        TABLE_STRING,
+                        pretty,
+                        TABLE_STRING,
+                        resolve_flags_to_string(flags));
+                if (r < 0)
+                        return table_log_add_error(r);
+        }
+
+        r = sd_bus_message_exit_container(reply);
+        if (r < 0)
+                return bus_log_parse_error(r);
+
+        r = table_print(table, NULL);
+        if (r < 0)
+                return table_log_print_error(r);
+
+        return 0;
+}
+
 static void help_protocol_types(void) {
         if (arg_legend)
                 puts("Known protocol types:");
@@ -2609,6 +2693,7 @@ static int native_help(void) {
                "  nta [LINK [DOMAIN...]]       Get/set per-interface DNSSEC NTA\n"
                "  revert LINK                  Revert per-interface configuration\n"
                "  log-level [LEVEL]            Get/set logging threshold for systemd-resolved\n"
+               "  show-multicast               Show domain names discovered via LLMNR/mDNS\n"
                "\nOptions:\n"
                "  -h --help                    Show this help\n"
                "     --version                 Show package version\n"
@@ -3152,7 +3237,7 @@ static int native_parse_argv(int argc, char *argv[]) {
 }
 
 static int native_main(int argc, char *argv[], sd_bus *bus) {
-
+        /* clang-format off */
         static const Verb verbs[] = {
                 { "help",                  VERB_ANY, VERB_ANY, 0,            verb_help             },
                 { "status",                VERB_ANY, VERB_ANY, VERB_DEFAULT, verb_status           },
@@ -3174,8 +3259,10 @@ static int native_main(int argc, char *argv[], sd_bus *bus) {
                 { "nta",                   VERB_ANY, VERB_ANY, 0,            verb_nta              },
                 { "revert",                VERB_ANY, 2,        0,            verb_revert_link      },
                 { "log-level",             VERB_ANY, 2,        0,            verb_log_level        },
+                { "show-multicast",        VERB_ANY, VERB_ANY, 0,            verb_show_multicast   },
                 {}
         };
+        /* clang-format on */
 
         return dispatch_verb(argc, argv, verbs, bus);
 }

src/resolve/resolved-bus.c

@@ -132,15 +132,17 @@ static int reply_query_state(DnsQuery *q) {
         }
 }
 
-static int append_address(sd_bus_message *reply, DnsResourceRecord *rr, int ifindex) {
+static int append_address(sd_bus_message *reply, DnsResourceRecord *rr, int ifindex, bool is_container) {
         int r;
 
         assert(reply);
         assert(rr);
 
+        if (is_container) {
                 r = sd_bus_message_open_container(reply, 'r', "iiay");
                 if (r < 0)
                         return r;
+        }
 
         r = sd_bus_message_append(reply, "i", ifindex);
         if (r < 0)
@@ -165,9 +167,11 @@ static int append_address(sd_bus_message *reply, DnsResourceRecord *rr, int ifin
         if (r < 0)
                 return r;
 
+        if (is_container) {
                 r = sd_bus_message_close_container(reply);
                 if (r < 0)
                         return r;
+        }
 
         return 0;
 }
@@ -216,7 +220,7 @@ static void bus_method_resolve_hostname_complete(DnsQuery *q) {
                 if (r == 0)
                         continue;
 
-                r = append_address(reply, rr, ifindex);
+                r = append_address(reply, rr, ifindex, true);
                 if (r < 0)
                         goto finish;
 
@@ -851,7 +855,7 @@ static int append_srv(DnsQuery *q, sd_bus_message *reply, DnsResourceRecord *rr)
                                 if (r == 0)
                                         continue;
 
-                                r = append_address(reply, zz, ifindex);
+                                r = append_address(reply, zz, ifindex, true);
                                 if (r < 0)
                                         return r;
                         }
@@ -2000,6 +2004,76 @@ static int bus_method_unregister_service(sd_bus_message *message, void *userdata
         return call_dnssd_method(m, message, bus_dnssd_method_unregister, error);
 }
 
+static int bus_method_get_multicast_hosts(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        DnsScope *s;
+        Manager *m = userdata;
+        int r;
+
+        assert(message);
+        assert(m);
+
+        r = sd_bus_message_new_method_return(message, &reply);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(reply, 'a', "(stiiay)");
+        if (r < 0)
+                return r;
+
+        LIST_FOREACH(scopes, s, m->dns_scopes) {
+                _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+                DnsResourceRecord *rr;
+                DnsAnswerFlags flags;
+                int ifindex;
+
+                if (s->protocol == DNS_PROTOCOL_DNS)
+                        continue;
+
+                r = dns_cache_dump_to_answer(&s->cache, &answer);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        continue;
+
+                DNS_ANSWER_FOREACH_FULL(rr, ifindex, flags, answer) {
+                        _cleanup_free_ char *normalized = NULL;
+                        bool authenticated = FLAGS_SET(flags, DNS_ANSWER_AUTHENTICATED);
+
+                        r = dns_name_normalize(dns_resource_key_name(rr->key), 0, &normalized);
+                        if (r < 0)
+                                return r;
+
+                        r = sd_bus_message_open_container(reply, 'r', "stiiay");
+                        if (r < 0)
+                                return r;
+
+                        r = sd_bus_message_append(
+                                reply,
+                                "st",
+                                normalized,
+                                SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, authenticated));
+                        if (r < 0)
+                                return r;
+
+                        r = append_address(reply, rr, ifindex, false);
+                        if (r < 0)
+                                return r;
+
+                        r = sd_bus_message_close_container(reply);
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        r = sd_bus_message_close_container(reply);
+        if (r < 0)
+                return r;
+
+        return sd_bus_reply(message, reply);
+}
+
+/* clang-format off */
 static const sd_bus_vtable resolve_vtable[] = {
         SD_BUS_VTABLE_START(0),
         SD_BUS_PROPERTY("LLMNRHostname", "s", NULL, offsetof(Manager, llmnr_hostname), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
@@ -2138,9 +2212,14 @@ static const sd_bus_vtable resolve_vtable[] = {
                                 SD_BUS_NO_RESULT,
                                 bus_method_reset_server_features,
                                 SD_BUS_VTABLE_UNPRIVILEGED),
-
+        SD_BUS_METHOD_WITH_ARGS("GetMulticastHosts",
+                                SD_BUS_NO_ARGS,
+                                SD_BUS_RESULT("a(stiiay)", addresses),
+                                bus_method_get_multicast_hosts,
+                                SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_VTABLE_END,
 };
+/* clang-format on */
 
 const BusObjectImplementation manager_object = {
         "/org/freedesktop/resolve1",

src/resolve/resolved-dns-cache.c

@@ -1066,7 +1066,55 @@ int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
         return 0;
 }
 
-void dns_cache_dump(DnsCache *cache, FILE *f) {
+int dns_cache_dump_to_answer(DnsCache *cache, DnsAnswer **ret) {
+        _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+        DnsCacheItem *i;
+        size_t n = 0;
+        int r;
+
+        assert(cache);
+        assert(ret);
+
+        HASHMAP_FOREACH(i, cache->by_key) {
+                DnsCacheItem *j;
+
+                LIST_FOREACH(by_key, j, i) {
+                        if (!j->rr)
+                                continue;
+
+                        n++;
+                }
+        }
+
+        if (n == 0) {
+                *ret = NULL;
+                return 0;
+        }
+
+        answer = dns_answer_new(n);
+        if (!answer)
+                return -ENOMEM;
+
+        HASHMAP_FOREACH(i, cache->by_key) {
+                DnsCacheItem *j;
+
+                LIST_FOREACH(by_key, j, i) {
+                        if (!j->rr)
+                                continue;
+
+                        r = dns_answer_add(
+                                answer, j->rr, j->ifindex, j->authenticated ? DNS_ANSWER_AUTHENTICATED : 0);
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        *ret = TAKE_PTR(answer);
+
+        return n;
+}
+
+void dns_cache_dump_to_file(DnsCache *cache, FILE *f) {
         DnsCacheItem *i;
 
         if (!cache)

src/resolve/resolved-dns-cache.h

@@ -27,7 +27,8 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, bool clamp_ttl, int *rcod
 
 int dns_cache_check_conflicts(DnsCache *cache, DnsResourceRecord *rr, int owner_family, const union in_addr_union *owner_address);
 
-void dns_cache_dump(DnsCache *cache, FILE *f);
+void dns_cache_dump_to_file(DnsCache *cache, FILE *f);
+int dns_cache_dump_to_answer(DnsCache *cache, DnsAnswer **answer);
 bool dns_cache_is_empty(DnsCache *cache);
 
 unsigned dns_cache_size(DnsCache *cache);

src/resolve/resolved-dns-scope.c

@@ -1159,7 +1159,7 @@ void dns_scope_dump(DnsScope *s, FILE *f) {
 
         if (!dns_cache_is_empty(&s->cache)) {
                 fputs("CACHE:\n", f);
-                dns_cache_dump(&s->cache, f);
+                dns_cache_dump_to_file(&s->cache, f);
         }
 }
 

src/test/test-fs-util.c

@@ -11,7 +11,6 @@
 #include "macro.h"
 #include "mkdir.h"
 #include "path-util.h"
-#include "random-util.h"
 #include "rm-rf.h"
 #include "stdio-util.h"
 #include "string-util.h"
@@ -837,24 +836,12 @@ static void test_path_is_encrypted(void) {
         test_path_is_encrypted_one("/dev", booted > 0 ? false : -1);
 }
 
-static void create_binary_file(const char *p, const void *data, size_t l) {
-        _cleanup_close_ int fd = -1;
-
-        fd = open(p, O_CREAT|O_WRONLY|O_EXCL|O_CLOEXEC, 0600);
-        assert_se(fd >= 0);
-        assert_se(write(fd, data, l) == (ssize_t) l);
-}
-
 static void test_conservative_rename(void) {
         _cleanup_(unlink_and_freep) char *p = NULL;
         _cleanup_free_ char *q = NULL;
-        size_t l = 16*1024 + random_u64() % (32 * 1024); /* some randomly sized buffer 16k…48k */
-        uint8_t buffer[l+1];
-
-        random_bytes(buffer, l);
 
         assert_se(tempfn_random_child(NULL, NULL, &p) >= 0);
-        create_binary_file(p, buffer, l);
+        assert_se(write_string_file(p, "this is a test", WRITE_STRING_FILE_CREATE) >= 0);
 
         assert_se(tempfn_random_child(NULL, NULL, &q) >= 0);
 
@@ -869,30 +856,27 @@ static void test_conservative_rename(void) {
         assert_se(access(q, F_OK) < 0 && errno == ENOENT);
 
         /* Check that a manual new writeout is also detected */
-        create_binary_file(q, buffer, l);
+        assert_se(write_string_file(q, "this is a test", WRITE_STRING_FILE_CREATE) >= 0);
         assert_se(conservative_renameat(AT_FDCWD, q, AT_FDCWD, p) == 0);
         assert_se(access(q, F_OK) < 0 && errno == ENOENT);
 
         /* Check that a minimally changed version is detected */
-        buffer[47] = ~buffer[47];
+        assert_se(write_string_file(q, "this is a_test", WRITE_STRING_FILE_CREATE) >= 0);
-        create_binary_file(q, buffer, l);
         assert_se(conservative_renameat(AT_FDCWD, q, AT_FDCWD, p) > 0);
         assert_se(access(q, F_OK) < 0 && errno == ENOENT);
 
         /* Check that this really is new updated version */
-        create_binary_file(q, buffer, l);
+        assert_se(write_string_file(q, "this is a_test", WRITE_STRING_FILE_CREATE) >= 0);
         assert_se(conservative_renameat(AT_FDCWD, q, AT_FDCWD, p) == 0);
         assert_se(access(q, F_OK) < 0 && errno == ENOENT);
 
         /* Make sure we detect extended files */
-        buffer[l++] = 47;
+        assert_se(write_string_file(q, "this is a_testx", WRITE_STRING_FILE_CREATE) >= 0);
-        create_binary_file(q, buffer, l);
         assert_se(conservative_renameat(AT_FDCWD, q, AT_FDCWD, p) > 0);
         assert_se(access(q, F_OK) < 0 && errno == ENOENT);
 
         /* Make sure we detect truncated files */
-        l--;
+        assert_se(write_string_file(q, "this is a_test", WRITE_STRING_FILE_CREATE) >= 0);
-        create_binary_file(q, buffer, l);
         assert_se(conservative_renameat(AT_FDCWD, q, AT_FDCWD, p) > 0);
         assert_se(access(q, F_OK) < 0 && errno == ENOENT);
 }