[1/3] batctl: Switch active routing algo list to netlink

diff --git a/routing_algo.c b/routing_algo.c
index 7171c52..5fa360b 100644
--- a/routing_algo.c
+++ b/routing_algo.c
@@ -6,7 +6,6 @@ 
  * License-Filename: LICENSES/preferred/GPL-2.0
  */
 
-#include <dirent.h>
 #include <errno.h>
 #include <getopt.h>
 #include <netinet/if_ether.h>
@@ -159,14 +158,130 @@  static int print_routing_algos(void)
 	return err;
 }
 
+static struct nla_policy link_policy[IFLA_MAX + 1] = {
+	[IFLA_IFNAME] = { .type = NLA_STRING, .maxlen = IFNAMSIZ },
+};
+
+struct print_ra_interfaces_rtnl_arg {
+	uint8_t header_shown:1;
+};
+
+static int print_ra_interfaces_rtnl_parse(struct nl_msg *msg, void *arg)
+{
+	struct print_ra_interfaces_rtnl_arg *print_arg = arg;
+	struct nlattr *attrs[IFLA_MAX + 1];
+	char algoname[256];
+	struct ifinfomsg *ifm;
+	char *mesh_iface;
+	int ret;
+
+	ifm = nlmsg_data(nlmsg_hdr(msg));
+	ret = nlmsg_parse(nlmsg_hdr(msg), sizeof(*ifm), attrs, IFLA_MAX,
+			  link_policy);
+	if (ret < 0)
+		goto err;
+
+	if (!attrs[IFLA_IFNAME])
+		goto err;
+
+	mesh_iface = nla_get_string(attrs[IFLA_IFNAME]);
+
+	ret = get_algoname_netlink(mesh_iface, algoname, sizeof(algoname));
+	if (ret < 0)
+		goto err;
+
+	if(!print_arg->header_shown) {
+		print_arg->header_shown = true;
+		printf("Active routing protocol configuration:\n");
+	}
+
+	printf(" * %s: %s\n", mesh_iface, algoname);
+
+err:
+	return NL_OK;
+}
+
+static int print_ra_interfaces(void)
+{
+	struct print_ra_interfaces_rtnl_arg print_arg = {};
+
+	struct ifinfomsg rt_hdr = {
+		.ifi_family = IFLA_UNSPEC,
+	};
+	struct nlattr *linkinfo;
+	struct nl_sock *sock;
+	struct nl_msg *msg;
+	struct nl_cb *cb;
+	int err = 0;
+	int ret;
+
+	sock = nl_socket_alloc();
+	if (!sock)
+		return -ENOMEM;
+
+	ret = nl_connect(sock, NETLINK_ROUTE);
+	if (ret < 0) {
+		err = -ENOMEM;
+		goto err_free_sock;
+	}
+
+	cb = nl_cb_alloc(NL_CB_DEFAULT);
+	if (!cb) {
+		err = -ENOMEM;
+		goto err_free_sock;
+	}
+
+	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, print_ra_interfaces_rtnl_parse,
+		 &print_arg);
+
+	msg = nlmsg_alloc_simple(RTM_GETLINK, NLM_F_REQUEST | NLM_F_DUMP);
+	if (!msg) {
+		err = -ENOMEM;
+		goto err_free_cb;
+	}
+
+	ret = nlmsg_append(msg, &rt_hdr, sizeof(rt_hdr), NLMSG_ALIGNTO);
+	if (ret < 0) {
+		err = -ENOMEM;
+		goto err_free_msg;
+	}
+
+	linkinfo = nla_nest_start(msg, IFLA_LINKINFO);
+	if (!linkinfo) {
+		err = -ENOMEM;
+		goto err_free_msg;
+	}
+
+	ret = nla_put_string(msg, IFLA_INFO_KIND, "batadv");
+	if (ret < 0) {
+		err = -ENOMEM;
+		goto err_free_msg;
+	}
+	nla_nest_end(msg, linkinfo);
+
+	ret = nl_send_auto_complete(sock, msg);
+	if (ret < 0)
+		goto err_free_msg;
+
+	nl_recvmsgs(sock, cb);
+
+	if (print_arg.header_shown)
+		printf("\n");
+
+err_free_msg:
+	nlmsg_free(msg);
+err_free_cb:
+	nl_cb_put(cb);
+err_free_sock:
+	nl_socket_free(sock);
+
+	return err;
+}
+
 static int routing_algo(struct state *state __maybe_unused, int argc, char **argv)
 {
-	DIR *iface_base_dir;
-	struct dirent *iface_dir;
 	int optchar;
-	char *path_buff;
 	int res = EXIT_FAILURE;
-	int first_iface = 1;
 
 	while ((optchar = getopt(argc, argv, "h")) != -1) {
 		switch (optchar) {
@@ -183,48 +298,10 @@  static int routing_algo(struct state *state __maybe_unused, int argc, char **arg
 
 	if (argc == 2) {
 		res = write_file(SYS_SELECTED_RA_PATH, "", argv[1], NULL);
-		goto out;
-	}
-
-	path_buff = malloc(PATH_BUFF_LEN);
-	if (!path_buff) {
-		fprintf(stderr, "Error - could not allocate path buffer: out of memory ?\n");
-		goto out;
-	}
-
-	iface_base_dir = opendir(SYS_IFACE_PATH);
-	if (!iface_base_dir) {
-		fprintf(stderr, "Error - the directory '%s' could not be read: %s\n",
-			SYS_IFACE_PATH, strerror(errno));
-		fprintf(stderr, "Is the batman-adv module loaded and sysfs mounted ?\n");
-		goto free_buff;
-	}
-
-	while ((iface_dir = readdir(iface_base_dir)) != NULL) {
-		snprintf(path_buff, PATH_BUFF_LEN, SYS_ROUTING_ALGO_FMT, iface_dir->d_name);
-		res = read_file("", path_buff, USE_READ_BUFF | SILENCE_ERRORS, 0, 0, 0);
-		if (res != EXIT_SUCCESS)
-			continue;
-
-		if (line_ptr[strlen(line_ptr) - 1] == '\n')
-			line_ptr[strlen(line_ptr) - 1] = '\0';
-
-		if (first_iface) {
-			first_iface = 0;
-			printf("Active routing protocol configuration:\n");
-		}
-
-		printf(" * %s: %s\n", iface_dir->d_name, line_ptr);
-
-		free(line_ptr);
-		line_ptr = NULL;
+		return EXIT_FAILURE;
 	}
 
-	closedir(iface_base_dir);
-	free(path_buff);
-
-	if (!first_iface)
-		printf("\n");
+	print_ra_interfaces();
 
 	res = read_file("", SYS_SELECTED_RA_PATH, USE_READ_BUFF, 0, 0, 0);
 	if (res != EXIT_SUCCESS)
@@ -237,11 +314,6 @@  static int routing_algo(struct state *state __maybe_unused, int argc, char **arg
 
 	print_routing_algos();
 	return EXIT_SUCCESS;
-
-free_buff:
-	free(path_buff);
-out:
-	return res;
 }
 
 COMMAND(SUBCOMMAND, routing_algo, "ra", 0, NULL,