resolved: beef up DNS server configuration logic

We now maintain two lists of DNS servers: system servers and fallback
servers.

system servers are used in combination with any per-link servers.

fallback servers are only used if there are no system servers or
per-link servers configured.

The system server list is supposed to be populated from a foreign tool's
/etc/resolv.conf (not implemented yet).

Also adds a configuration switch for LLMNR, that allows configuring
whether LLMNR shall be used simply for resolving or also for responding.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/resolve/resolved-dns-server.h b/src/resolve/resolved-dns-server.h
index 574616ef0f..358bbd43d6 100644
--- a/src/resolve/resolved-dns-server.h
+++ b/src/resolve/resolved-dns-server.h
@@ -30,9 +30,17 @@ typedef enum DnsServerSource DnsServerSource;
 #include "resolved-link.h"
 #include "resolved-dns-server.h"
 
+typedef enum DnsServerType {
+        DNS_SERVER_SYSTEM,
+        DNS_SERVER_FALLBACK,
+        DNS_SERVER_LINK,
+} DnsServerType;
+
 struct DnsServer {
         Manager *manager;
 
+        DnsServerType type;
+
         Link *link;
 
         int family;
@@ -46,6 +54,7 @@ struct DnsServer {
 int dns_server_new(
                 Manager *m,
                 DnsServer **s,
+                DnsServerType type,
                 Link *l,
                 int family,
                 const union in_addr_union *address);