batctl: introduce rtnl_open() helper function

index 13ba190..50bb834 100644
@@ -497,30 +497,27 @@ static void request_mac_resolve(int ai_family, const void *l3addr)
 	close(sock);
 }
 
-static int resolve_mac_from_cache_open(int ai_family)
+/**
+ * rtnl_open - open a socket to rtnl and send a request
+ * @nh: the header of the request to send
+ * @protocol: the protocol to use when opening the socket
+ *
+ * Return 0 on success or a negative error code otherwise
+ */
+static int rtnl_open(struct nlmsghdr *nh, int protocol)
 {
-	int socknl;
-	int ret;
-	struct {
-		struct nlmsghdr hdr;
-		struct ndmsg msg;
-	} nlreq;
-	struct sockaddr_nl addrnl;
 	static uint32_t nr_call = 0;
 	uint32_t pid = (++nr_call + getpid()) & 0x3FFFFF;
+	struct sockaddr_nl addrnl;
+	int socknl;
+	int ret;
 
 	memset(&addrnl, 0, sizeof(addrnl));
 	addrnl.nl_family = AF_NETLINK;
 	addrnl.nl_pid = pid;
 	addrnl.nl_groups = 0;
 
-	memset(&nlreq, 0, sizeof(nlreq));
-	nlreq.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(nlreq.msg));
-	nlreq.hdr.nlmsg_type = RTM_GETNEIGH;
-	nlreq.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
-	nlreq.msg.ndm_family = ai_family;
-
-	socknl = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+	socknl = socket(AF_NETLINK, SOCK_RAW, protocol);
 	if (socknl < 0)
 		goto out;
 

@@ -528,7 +525,7 @@ static int resolve_mac_from_cache_open(int ai_family)
 	if (ret < 0)
 		goto outclose;
 
-	ret = send(socknl, &nlreq, nlreq.hdr.nlmsg_len, 0);
+	ret = send(socknl, nh, nh->nlmsg_len, 0);
 	if (ret < 0)
 		goto outclose;
 out:

@@ -538,6 +535,22 @@ outclose:
 	return ret;
 }
 
+static int resolve_mac_from_cache_open(int ai_family)
+{
+	struct {
+		struct nlmsghdr hdr;
+		struct ndmsg msg;
+	} nlreq;
+
+	memset(&nlreq, 0, sizeof(nlreq));
+	nlreq.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(nlreq.msg));
+	nlreq.hdr.nlmsg_type = RTM_GETNEIGH;
+	nlreq.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+	nlreq.msg.ndm_family = ai_family;
+
+	return rtnl_open(&nlreq.hdr, NETLINK_ROUTE);
+}
+
 static ssize_t resolve_mac_from_cache_dump(int sock, void **buf, size_t *buflen)
 {
 	struct iovec iov;

index 50bb834..fdae6fa 100644
@@ -40,6 +40,7 @@
 #include <linux/neighbour.h>
 #include <sys/uio.h>
 #include <errno.h>
+#include <net/if.h>
 
 #include "main.h"
 #include "functions.h"

@@ -764,3 +765,167 @@ struct ether_addr *resolve_mac(const char *asc)
 out:
 	return mac_result;
 }
+
+/**
+ * vlan_get_link_parse - parse a get_link rtnl message and extract the important
+ *  data
+ * @nh: the reply header
+ * @iface: pointer to the buffer where the link interface has to be stored (it
+ *  is allocated by this function)
+ *
+ * Return the vid in case of success or -1 otherwise
+ */
+static int vlan_get_link_parse(struct nlmsghdr *nh, char **iface)
+{
+	struct ifinfomsg *ifi = NLMSG_DATA(nh);
+	size_t vlan_len, info_len, len = nh->nlmsg_len;
+	struct rtattr *rta, *info, *vlan;
+	int idx = -1, vid = -1;
+
+	*iface = NULL;
+
+	rta = IFLA_RTA(ifi);
+	while (RTA_OK(rta, len)) {
+		/* check if the interface is a vlan */
+		if (rta->rta_type == IFLA_LINKINFO) {
+			info = RTA_DATA(rta);
+			info_len = RTA_PAYLOAD(rta);
+
+			while (RTA_OK(info, info_len)) {
+				if (info->rta_type == IFLA_INFO_KIND &&
+				    strcmp(RTA_DATA(info), "vlan"))
+					goto err;
+
+				if (info->rta_type == IFLA_INFO_DATA) {
+					vlan = RTA_DATA(info);
+					vlan_len = RTA_PAYLOAD(info);
+
+					while (RTA_OK(vlan, vlan_len)) {
+						if (vlan->rta_type == IFLA_VLAN_ID)
+							vid = *(int *)RTA_DATA(vlan);
+						vlan = RTA_NEXT(vlan, vlan_len);
+					}
+				}
+				info = RTA_NEXT(info, info_len);
+			}
+		}
+
+		/* extract the name of the "link" interface */
+		if (rta->rta_type == IFLA_LINK) {
+			idx = *(int *)RTA_DATA(rta);
+
+			*iface = malloc(IFNAMSIZ + 1);
+			if (!if_indextoname(idx, *iface))
+				goto err;
+		}
+		rta = RTA_NEXT(rta, len);
+	}
+
+	if (vid == -1)
+		goto err;
+
+	if (idx <= 0)
+		goto err;
+
+	return vid;
+err:
+	free(*iface);
+	return -1;
+}
+
+/**
+ * vlan_get_link_dump - receive and dump a get_link rtnl reply
+ * @sock: the socket to listen for the reply on
+ * @buf: buffer where the reply has to be dumped to
+ * @buflen: length of the buffer
+ *
+ * Returns the amount of dumped bytes
+ */
+static ssize_t vlan_get_link_dump(int sock, void *buf, size_t buflen)
+{
+	struct sockaddr_nl nladdr;
+	struct msghdr msg;
+	struct iovec iov;
+
+	memset(&msg, 0, sizeof(msg));
+	memset(&iov, 0, sizeof(iov));
+
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	msg.msg_controllen = 0;
+	msg.msg_control = NULL;
+	msg.msg_flags = 0;
+	msg.msg_name = &nladdr;
+	msg.msg_namelen = sizeof(nladdr);
+
+	iov.iov_len = buflen;
+	iov.iov_base = buf;
+
+	return recvmsg(sock, &msg, 0);
+}
+
+/**
+ * vlan_get_link_open - send a get_link request
+ * @ifname: the interface to query
+ *
+ * Returns 0 in case of success or a negative error code otherwise
+ */
+static int vlan_get_link_open(const char *ifname)
+{
+	struct {
+		struct nlmsghdr hdr;
+		struct ifinfomsg ifi;
+		/* attribute has to be NLMSG aligned */
+		struct rtattr rta_ifname __attribute__ ((aligned(NLMSG_ALIGNTO)));
+		char ifname[IFNAMSIZ + 1];
+	} nlreq;
+
+	memset(&nlreq, 0, sizeof(nlreq));
+	nlreq.hdr.nlmsg_len = sizeof(nlreq);
+	nlreq.hdr.nlmsg_type = RTM_GETLINK;
+	nlreq.hdr.nlmsg_flags = NLM_F_REQUEST;
+	nlreq.ifi.ifi_family = AF_UNSPEC;
+
+	nlreq.rta_ifname.rta_type = IFLA_IFNAME;
+	nlreq.rta_ifname.rta_len = IFNAMSIZ + 1;
+	strncpy(nlreq.ifname, ifname, IFNAMSIZ);
+
+	return rtnl_open(&nlreq.hdr, 0);
+}
+
+/**
+ * vlan_get_link - convert a VLAN interface into its parent one
+ * @ifname: the interface to convert
+ * @parent: buffer where the parent interface name will be written (allocated by
+ *  this function)
+ *
+ * Returns the vlan identifier on success or -1 on error
+ */
+int vlan_get_link(const char *ifname, char **parent)
+{
+	int vid = -1, socknl;
+	void *buf = NULL;
+	size_t buflen;
+	ssize_t len;
+
+	buflen = 8192;
+	buf = malloc(buflen);
+	if (!buf)
+		goto err;
+
+	socknl = vlan_get_link_open(ifname);
+	if (socknl < 0)
+		goto err;
+
+	len = vlan_get_link_dump(socknl, buf, buflen);
+	if (len < 0)
+		goto err_sock;
+
+	vid = vlan_get_link_parse(buf, parent);
+
+err_sock:
+	close(socknl);
+err:
+	free(buf);
+	return vid;
+}

index 522c607..14ba525 100644
@@ -42,6 +42,7 @@ int write_file(const char *dir, const char *fname, const char *arg1,
 	       const char *arg2);
 struct ether_addr *translate_mac(char *mesh_iface, struct ether_addr *mac);
 struct ether_addr *resolve_mac(const char *asc);
+int vlan_get_link(const char *ifname, char **parent);
 
 extern char *line_ptr;
 

index aab2e11..a37c0b7 100644
@@ -46,7 +46,7 @@ static void print_usage(void)
 
 	fprintf(stderr, "Usage: batctl [options] command|debug table [parameters]\n");
 	fprintf(stderr, "options:\n");
-	fprintf(stderr, " \t-m mesh interface (default 'bat0')\n");
+	fprintf(stderr, " \t-m mesh interface or VLAN created on top of a mesh interface (default 'bat0')\n");
 	fprintf(stderr, " \t-h print this help (or 'batctl <command|debug table> -h' for the parameter help)\n");
 	fprintf(stderr, " \t-v print version\n");
 	fprintf(stderr, "\n");

index 2a508e2..5cebf52 100644
@@ -372,8 +372,8 @@ static void settings_usage(int setting)
 
 int handle_sys_setting(char *mesh_iface, int setting, int argc, char **argv)
 {
-	int optchar, res = EXIT_FAILURE;
-	char *path_buff;
+	int vid, optchar, res = EXIT_FAILURE;
+	char *path_buff, *base_dev = NULL;
 	const char **ptr;
 
 	while ((optchar = getopt(argc, argv, "h")) != -1) {

@@ -387,10 +387,20 @@ int handle_sys_setting(char *mesh_iface, int setting, int argc, char **argv)
 		}
 	}
 
+	/* prepare the classic path */
 	path_buff = malloc(PATH_BUFF_LEN);
 	snprintf(path_buff, PATH_BUFF_LEN, SYS_BATIF_PATH_FMT, mesh_iface);
 	path_buff[PATH_BUFF_LEN - 1] = '\0';
 
+	/* if the specified interface is a VLAN then change the path to point
+	 * to the proper "vlan%{vid}" subfolder in the sysfs tree.
+	 */
+	vid = vlan_get_link(mesh_iface, &base_dev);
+	if (vid >= 0) {
+		snprintf(path_buff, PATH_BUFF_LEN, SYS_VLAN_PATH, base_dev, vid);
+		path_buff[PATH_BUFF_LEN - 1] = '\0';
+	}
+
 	if (argc == 1) {
 		res = read_file(path_buff, (char *)batctl_settings[setting].sysfs_name,
 				NO_FLAGS, 0, 0, 0);

@@ -425,6 +435,7 @@ write_file:
 
 out:
 	free(path_buff);
+	free(base_dev);
 	return res;
 }
 

index 8934978..2cbbcfb 100644
@@ -24,16 +24,18 @@
 
 #include "main.h"
 
-#define SYS_BATIF_PATH_FMT "/sys/class/net/%s/mesh/"
-#define SYS_LOG_LEVEL "log_level"
-#define SYS_LOG "log"
-#define SYS_GW_MODE "gw_mode"
-#define SYS_GW_SEL "gw_sel_class"
-#define SYS_GW_BW "gw_bandwidth"
-#define SYS_IFACE_PATH "/sys/class/net"
-#define SYS_IFACE_DIR SYS_IFACE_PATH"/%s/"
-#define SYS_MESH_IFACE_FMT SYS_IFACE_PATH"/%s/batman_adv/mesh_iface"
-#define SYS_IFACE_STATUS_FMT SYS_IFACE_PATH"/%s/batman_adv/iface_status"
+#define SYS_BATIF_PATH_FMT	"/sys/class/net/%s/mesh/"
+#define SYS_LOG_LEVEL		"log_level"
+#define SYS_LOG			"log"
+#define SYS_GW_MODE		"gw_mode"
+#define SYS_GW_SEL		"gw_sel_class"
+#define SYS_GW_BW		"gw_bandwidth"
+#define SYS_IFACE_PATH		"/sys/class/net"
+#define SYS_IFACE_DIR		SYS_IFACE_PATH"/%s/"
+#define SYS_MESH_IFACE_FMT	SYS_IFACE_PATH"/%s/batman_adv/mesh_iface"
+#define SYS_IFACE_STATUS_FMT	SYS_IFACE_PATH"/%s/batman_adv/iface_status"
+#define SYS_VLAN_PATH		SYS_IFACE_PATH"/%s/mesh/vlan%d/"
+#define VLAN_ID_MAX_LEN		4
 
 enum batctl_settings_list {
 	BATCTL_SETTINGS_ORIG_INTERVAL,