resolved: log server type when switching servers

I'm not defining _DNS_SERVER_TYPE_MAX/INVALID as usual in the enum,
because it wouldn't be used, and then gcc would complain that
various enums don't test for _DNS_SERVER_TYPE_MAX. It seems better
to define the macro rather than add assert_not_reached() in multiple
places.

2 files changed, 15 insertions, 2 deletions

diff --git a/src/resolve/resolved-dns-server.c b/src/resolve/resolved-dns-server.c
index e1d2025863..43ec92f4f0 100644
--- a/src/resolve/resolved-dns-server.c
+++ b/src/resolve/resolved-dns-server.c
@@ -657,7 +657,9 @@ DnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
                 return s;
 
         if (s)
-                log_info("Switching to system DNS server %s.", dns_server_string(s));
+                log_info("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);
@@ -675,7 +677,7 @@ DnsServer *manager_get_dns_server(Manager *m) {
         /* Try to read updates resolv.conf */
         manager_read_resolv_conf(m);
 
-        /* If no DNS server was chose so far, pick the first one */
+        /* If no DNS server was chosen so far, pick the first one */
         if (!m->current_dns_server)
                 manager_set_dns_server(m, m->dns_servers);
 
@@ -723,6 +725,13 @@ void manager_next_dns_server(Manager *m) {
                 manager_set_dns_server(m, m->dns_servers);
 }
 
+static const char* const dns_server_type_table[_DNS_SERVER_TYPE_MAX] = {
+        [DNS_SERVER_SYSTEM] = "system",
+        [DNS_SERVER_FALLBACK] = "fallback",
+        [DNS_SERVER_LINK] = "link",
+};
+DEFINE_STRING_TABLE_LOOKUP(dns_server_type, DnsServerType);
+
 static const char* const dns_server_feature_level_table[_DNS_SERVER_FEATURE_LEVEL_MAX] = {
         [DNS_SERVER_FEATURE_LEVEL_TCP] = "TCP",
         [DNS_SERVER_FEATURE_LEVEL_UDP] = "UDP",
diff --git a/src/resolve/resolved-dns-server.h b/src/resolve/resolved-dns-server.h
index 2a3c921678..7a885655a4 100644
--- a/src/resolve/resolved-dns-server.h
+++ b/src/resolve/resolved-dns-server.h
@@ -30,6 +30,10 @@ typedef enum DnsServerType {
         DNS_SERVER_FALLBACK,
         DNS_SERVER_LINK,
 } DnsServerType;
+#define _DNS_SERVER_TYPE_MAX (DNS_SERVER_LINK + 1)
+
+const char* dns_server_type_to_string(DnsServerType i) _const_;
+DnsServerType dns_server_type_from_string(const char *s) _pure_;
 
 typedef enum DnsServerFeatureLevel {
         DNS_SERVER_FEATURE_LEVEL_TCP,