dhcp: export the DHCPv6 FQDN option

The dhclient backend already exports all the option passed by
dhclient, including the FDQN. Export it also for the systemd backend.

src/dhcp/nm-dhcp-options.c

@@ -183,6 +183,7 @@ const NMDhcpOption _nm_dhcp_option_dhcp6_options[] = {
 	REQ (NM_DHCP_OPTION_DHCP6_DNS_SERVERS,                      "dhcp6_name_servers",  TRUE ),
 	REQ (NM_DHCP_OPTION_DHCP6_DOMAIN_LIST,                      "dhcp6_domain_search", TRUE ),
 	REQ (NM_DHCP_OPTION_DHCP6_SNTP_SERVERS,                     "dhcp6_sntp_servers",  TRUE ),
+	REQ (NM_DHCP_OPTION_DHCP6_FQDN,                             "fqdn_fqdn",           FALSE ),
 	REQ (NM_DHCP_OPTION_DHCP6_MUD_URL,                          "dhcp6_mud_url",       FALSE ),
 
 	/* Internal values */

src/dhcp/nm-dhcp-options.h

@@ -160,7 +160,9 @@ typedef enum {
 	NM_DHCP_OPTION_DHCP6_DNS_SERVERS       = 23,
 	NM_DHCP_OPTION_DHCP6_DOMAIN_LIST       = 24,
 	NM_DHCP_OPTION_DHCP6_SNTP_SERVERS      = 31,
+	NM_DHCP_OPTION_DHCP6_FQDN              = 39,
 	NM_DHCP_OPTION_DHCP6_MUD_URL           = 112,
+
 	/* Internal values */
 	NM_DHCP_OPTION_DHCP6_NM_IP_ADDRESS     = 1026,
 	NM_DHCP_OPTION_DHCP6_NM_PREFIXLEN      = 1027,

src/dhcp/nm-dhcp-systemd.c

@@ -740,6 +740,7 @@ lease_to_ip6_config (NMDedupMultiIndex *multi_idx,
 	uint32_t lft_pref, lft_valid;
 	char addr_str[NM_UTILS_INET_ADDRSTRLEN];
 	char **domains;
+	const char *s;
 	nm_auto_free_gstring GString *str = NULL;
 	int num, i;
 
@@ -808,6 +809,13 @@ lease_to_ip6_config (NMDedupMultiIndex *multi_idx,
 		                           str->str);
 	}
 
+	if (sd_dhcp6_lease_get_fqdn (lease, &s) >= 0) {
+		nm_dhcp_option_add_option (options,
+		                           _nm_dhcp_option_dhcp6_options,
+		                           NM_DHCP_OPTION_DHCP6_FQDN,
+		                           s);
+	}
+
 	NM_SET_OUT (out_options, g_steal_pointer (&options));
 	return g_steal_pointer (&ip6_config);
 }