resolved: rework synthesizing logic

With this change we'll now also generate synthesized RRs for the local
LLMNR hostname (first label of system hostname), the local mDNS hostname
(first label of system hostname suffixed with .local), the "gateway"
hostname and all the reverse PTRs. This hence takes over part of what
nss-myhostname already implemented.

Local hostnames resolve to the set of local IP addresses. Since the
addresses are possibly on different interfaces it is necessary to change
the internal DnsAnswer object to track per-RR interface indexes, and to
change the bus API to always return the interface per-address rather than
per-reply. This change also patches  the existing clients for resolved
accordingly (nss-resolve + systemd-resolve-host).

This also changes the routing logic for queries slightly: we now ensure
that the local hostname is never resolved via LLMNR, thus making it
trustable on the local system.

1 files changed, 6 insertions, 3 deletions

diff --git a/src/resolve/resolved-manager.h b/src/resolve/resolved-manager.h
index 53b5acb33c..6f7972bbf3 100644
--- a/src/resolve/resolved-manager.h
+++ b/src/resolve/resolved-manager.h
@@ -91,9 +91,10 @@ struct Manager {
         sd_event_source *bus_retry_event_source;
 
         /* The hostname we publish on LLMNR and mDNS */
-        char *hostname;
-        DnsResourceKey *host_ipv4_key;
-        DnsResourceKey *host_ipv6_key;
+        char *llmnr_hostname;
+        char *mdns_hostname;
+        DnsResourceKey *llmnr_host_ipv4_key;
+        DnsResourceKey *llmnr_host_ipv6_key;
 
         /* Watch the system hostname */
         int hostname_fd;
@@ -140,5 +141,7 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free);
 
 #define EXTRA_CMSG_SPACE 1024
 
+int manager_is_own_hostname(Manager *m, const char *name);
+
 const char* support_to_string(Support p) _const_;
 int support_from_string(const char *s) _pure_;