routing/alfred/patches/0001-alfred-vis-Use-rtnl-to-query-list-of-hardifs-of-mesh.patch

From: Sven Eckelmann <sven@narfation.org>
Date: Wed, 19 Jun 2019 21:38:09 +0200
Subject: alfred: vis: Use rtnl to query list of hardifs of meshif

The normal way of network related programs to query the state of interfaces
is to use the rtnetlink. Most of these data can also be queried via sysfs
but it is better to use the same way for both retrieving the list of
interfaces and modifying the list of interfaces.

Also the sysfs files are deprecated and cause warnings when access:

  batman_adv: [Deprecated]: batadv-vis (pid 832) Use of sysfs file "mesh_iface".
  Use batadv genl family instead

In worst case, the file doesn't even exist when batman-adv was compiled
without sysfs support.

Reported-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

Origin: upstream, https://git.open-mesh.org/alfred.git/commit/a34f044de561ce90f67b5760059f818bfb35b449

diff --git a/vis/vis.c b/vis/vis.c
index beaeca150bcac583e9506b9504fa026131f50d5d..37956b100fad72257f5bab2b9f49908da59520cc 100644
--- a/vis/vis.c
+++ b/vis/vis.c
@@ -372,70 +372,146 @@ static void clear_lists(struct globals *globals)
 	}
 }
 
+static int query_rtnl_link(int ifindex, nl_recvmsg_msg_cb_t func, void *arg)
+{
+	struct ifinfomsg rt_hdr = {
+		.ifi_family = IFLA_UNSPEC,
+	};
+	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, func, 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;
+	}
+
+	ret = nla_put_u32(msg, IFLA_MASTER, ifindex);
+	if (ret < 0) {
+		err = -ENOMEM;
+		goto err_free_msg;
+	}
+
+	ret = nl_send_auto_complete(sock, msg);
+	if (ret < 0)
+		goto err_free_msg;
+
+	nl_recvmsgs(sock, cb);
+
+err_free_msg:
+	nlmsg_free(msg);
+err_free_cb:
+	nl_cb_put(cb);
+err_free_sock:
+	nl_socket_free(sock);
+
+	return err;
+}
+
+struct register_interfaces_rtnl_arg {
+	struct globals *globals;
+	int ifindex;
+};
+
+static struct nla_policy link_policy[IFLA_MAX + 1] = {
+	[IFLA_IFNAME] = { .type = NLA_STRING, .maxlen = IFNAMSIZ },
+	[IFLA_MASTER] = { .type = NLA_U32 },
+};
+
+static int register_interfaces_rtnl_parse(struct nl_msg *msg, void *arg)
+{
+	struct register_interfaces_rtnl_arg *register_arg = arg;
+	struct nlattr *attrs[IFLA_MAX + 1];
+	char path_buff[PATH_BUFF_LEN];
+	struct ifinfomsg *ifm;
+	char *content_newline;
+	char *file_content;
+	char *ifname;
+	int master;
+	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;
+
+	if (!attrs[IFLA_MASTER])
+		goto err;
+
+	ifname = nla_get_string(attrs[IFLA_IFNAME]);
+	master = nla_get_u32(attrs[IFLA_MASTER]);
+
+	/* required on older kernels which don't prefilter the results */
+	if (master != register_arg->ifindex)
+		goto err;
+
+	snprintf(path_buff, PATH_BUFF_LEN, SYS_IFACE_STATUS_FMT, ifname);
+	file_content = read_file(path_buff);
+	if (!file_content)
+		goto free_file;
+
+	content_newline = strstr(file_content, "\n");
+	if (content_newline)
+		*content_newline = '\0';
+
+	if (strcmp(file_content, "active") != 0)
+		goto err;
+
+	get_if_index_byname(register_arg->globals, ifname);
+
+free_file:
+	free(file_content);
+	file_content = NULL;
+err:
+	return NL_OK;
+}
+
 static int register_interfaces(struct globals *globals)
 {
-	DIR *iface_base_dir;
-	struct dirent *iface_dir;
-	char *path_buff, *file_content;
-	char *content_newline;
+	struct register_interfaces_rtnl_arg register_arg = {
+		.globals = globals,
+	};
 
-	path_buff = malloc(PATH_BUFF_LEN);
-	if (!path_buff) {
-		perror("Error - could not allocate path buffer");
-		goto err;
-	}
+	register_arg.ifindex = if_nametoindex(globals->interface);
+	if (!globals->interface)
+		return EXIT_FAILURE;
 
-	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 err_buff;
-	}
 
-	while ((iface_dir = readdir(iface_base_dir)) != NULL) {
-		snprintf(path_buff, PATH_BUFF_LEN, SYS_MESH_IFACE_FMT, iface_dir->d_name);
-		file_content = read_file(path_buff);
-		if (!file_content)
-			continue;
+	query_rtnl_link(register_arg.ifindex, register_interfaces_rtnl_parse,
+			&register_arg);
 
-		if (file_content[strlen(file_content) - 1] == '\n')
-			file_content[strlen(file_content) - 1] = '\0';
-
-		if (strcmp(file_content, "none") == 0)
-			goto free_line;
-
-		if (strcmp(file_content, globals->interface) != 0)
-			goto free_line;
-
-		free(file_content);
-		file_content = NULL;
-
-		snprintf(path_buff, PATH_BUFF_LEN, SYS_IFACE_STATUS_FMT, iface_dir->d_name);
-		file_content = read_file(path_buff);
-		if (!file_content)
-			continue;
-
-		content_newline = strstr(file_content, "\n");
-		if (content_newline)
-			*content_newline = '\0';
-
-		if (strcmp(file_content, "active") == 0)
-			get_if_index_byname(globals, iface_dir->d_name);
-
-free_line:
-		free(file_content);
-		file_content = NULL;
-	}
-
-	free(path_buff);
-	closedir(iface_base_dir);
 	return EXIT_SUCCESS;
-
-err_buff:
-	free(path_buff);
-err:
-	return EXIT_FAILURE;
 }
 
 static const int parse_orig_list_mandatory[] = {
diff --git a/vis/vis.h b/vis/vis.h
index 6870dd4ad8570135f4ab2edf0219d74778b7d061..b04a89351778806e84acae88ff3869cf68bcb1a3 100644
--- a/vis/vis.h
+++ b/vis/vis.h
@@ -25,7 +25,6 @@
 
 #define SYS_IFACE_PATH				"/sys/class/net"
 #define DEBUG_BATIF_PATH_FMT			"%s/batman_adv/%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"