netconfig: Track local domains lists

Cache the latest v4 and v6 domain string lists in struct netconfig state
to be able to more easily detect changes in those values in future
commits.  For that split netconfig_set_domains's code into this function,
which now only commits the values in netconfig->v{4,6}_domain{,s} to the
resolver, and netconfig_domains_update() which figures out the active
domains string list and saves it into netconfig->v{4,6}_domain{,s}.  This
probably saves some cycles as the callers can now decide to only
recalculate the domains list which may have changed.

While there simplify netconfig_set_domains return type to void as the
result was always 0 anyway and was never checked by callers.

src/netconfig.c

@@ -67,6 +67,8 @@ struct netconfig {
 	struct ie_fils_ip_addr_response_info *fils_override;
 	char *v4_gateway_str;
 	char *v6_gateway_str;
+	char *v4_domain;
+	char **v6_domains;
 
 	const struct l_settings *active_settings;
 
@@ -353,19 +355,34 @@ static void append_domain(char **domains, unsigned int *n_domains,
 	*n_domains += 1;
 }
 
-static int netconfig_set_domains(struct netconfig *netconfig)
+static void netconfig_set_domains(struct netconfig *netconfig)
 {
 	char *domains[31];
 	unsigned int n_domains = 0;
-	char *v4_domain = NULL;
-	char **v6_domains = NULL;
 	char **p;
 
 	memset(domains, 0, sizeof(domains));
 
+	append_domain(domains, &n_domains,
+			L_ARRAY_SIZE(domains) - 1, netconfig->v4_domain);
+
+	for (p = netconfig->v6_domains; p && *p; p++)
+		append_domain(domains, &n_domains,
+				L_ARRAY_SIZE(domains) - 1, *p);
+
+	resolve_set_domains(netconfig->resolve, domains);
+}
+
+static bool netconfig_domains_update(struct netconfig *netconfig, uint8_t af)
+{
+	bool changed = false;
+
+	if (af == AF_INET) {
 		/* Allow to override the DHCP domain name with setting entry. */
-	v4_domain = l_settings_get_string(netconfig->active_settings,
+		char *v4_domain = l_settings_get_string(
+						netconfig->active_settings,
 						"IPv4", "DomainName");
+
 		if (!v4_domain && netconfig->rtm_protocol == RTPROT_DHCP) {
 			const struct l_dhcp_lease *lease =
 				l_dhcp_client_get_lease(netconfig->dhcp_client);
@@ -374,26 +391,35 @@ static int netconfig_set_domains(struct netconfig *netconfig)
 				v4_domain = l_dhcp_lease_get_domain_name(lease);
 		}
 
-	append_domain(domains, &n_domains,
+		if (l_streq0(v4_domain, netconfig->v4_domain))
-					L_ARRAY_SIZE(domains) - 1, v4_domain);
+			l_free(v4_domain);
+		else {
+			l_free(netconfig->v4_domain);
+			netconfig->v4_domain = v4_domain;
+			changed = true;
+		}
+	} else {
+		char **v6_domains = NULL;
 
 		if (netconfig->rtm_v6_protocol == RTPROT_DHCP) {
 			const struct l_dhcp6_lease *lease =
-			l_dhcp6_client_get_lease(netconfig->dhcp6_client);
+				l_dhcp6_client_get_lease(
+						netconfig->dhcp6_client);
 
 			if (lease)
 				v6_domains = l_dhcp6_lease_get_domains(lease);
 		}
 
-	for (p = v6_domains; p && *p; p++)
+		if (l_strv_eq(netconfig->v6_domains, v6_domains))
-		append_domain(domains, &n_domains,
-					L_ARRAY_SIZE(domains) - 1, *p);
-
-	resolve_set_domains(netconfig->resolve, domains);
 			l_strv_free(v6_domains);
-	l_free(v4_domain);
+		else {
+			l_strv_free(netconfig->v6_domains);
+			netconfig->v6_domains = v6_domains;
+			changed = true;
+		}
+	}
 
-	return 0;
+	return changed;
 }
 
 static struct l_rtnl_address *netconfig_get_static4_address(
@@ -1022,6 +1048,7 @@ static void netconfig_ipv4_dhcp_event_handler(struct l_dhcp_client *client,
 		}
 
 		netconfig_dns_list_update(netconfig, AF_INET);
+		netconfig_domains_update(netconfig, AF_INET);
 
 		L_WARN_ON(!(netconfig->addr4_add_cmd_id =
 				l_rtnl_ifaddr_add(rtnl, netconfig->ifindex,
@@ -1093,6 +1120,7 @@ static void netconfig_dhcp6_event_handler(struct l_dhcp6_client *client,
 		netconfig->v6_address = address;
 
 		netconfig_dns_list_update(netconfig, AF_INET6);
+		netconfig_domains_update(netconfig, AF_INET6);
 		netconfig_set_dns(netconfig);
 		netconfig_set_domains(netconfig);
 		break;
@@ -1100,6 +1128,7 @@ static void netconfig_dhcp6_event_handler(struct l_dhcp6_client *client,
 	case L_DHCP6_CLIENT_EVENT_LEASE_EXPIRED:
 		l_debug("Lease for interface %u expired", netconfig->ifindex);
 		netconfig_dns_list_update(netconfig, AF_INET6);
+		netconfig_domains_update(netconfig, AF_INET6);
 		netconfig_set_dns(netconfig);
 		netconfig_set_domains(netconfig);
 		l_rtnl_address_free(netconfig->v6_address);
@@ -1143,6 +1172,8 @@ static void netconfig_reset_v4(struct netconfig *netconfig)
 		netconfig->acd = NULL;
 
 		l_free(l_steal_ptr(netconfig->v4_gateway_str));
+
+		l_free(l_steal_ptr(netconfig->v4_domain));
 	}
 }
 
@@ -1220,6 +1251,7 @@ static bool netconfig_ipv4_select_and_install(struct netconfig *netconfig)
 			return false;
 
 		netconfig_dns_list_update(netconfig, AF_INET);
+		netconfig_domains_update(netconfig, AF_INET);
 
 		netconfig->acd = l_acd_new(netconfig->ifindex);
 		l_acd_set_event_handler(netconfig->acd,
@@ -1542,6 +1574,8 @@ bool netconfig_reset(struct netconfig *netconfig)
 						"disable_ipv6", "1");
 
 		l_free(l_steal_ptr(netconfig->v6_gateway_str));
+
+		l_strv_free(l_steal_ptr(netconfig->v6_domains));
 	}
 
 	l_free(l_steal_ptr(netconfig->fils_override));