openwrt-routing/alfred/patches/0002-alfred-vis-Retrieve-hardif-status-via-generic-netlin.patch

From: Sven Eckelmann <sven@narfation.org>
Date: Wed, 19 Jun 2019 21:38:10 +0200
Subject: alfred: vis: Retrieve hardif status via generic netlink

The batman-adv kernel module can now be compiled without support for sysfs.
But the batadv-vis interface retriever can only get the status via the per
hardif sysfs file iface_status. To still have some information, use
BATADV_CMD_GET_HARDIF to retrieve the status and fall back to sysfs when
the status could not retrieved via generic netlink.

This also solved the warning about deprecated sysfs file access

  batman_adv: [Deprecated]: batadv-vis (pid 1365) Use of sysfs file "iface_status".
  Use batadv genl family instead

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/0fc6e6674428ce7085b07645895ef837604e18b5

diff --git a/vis/vis.c b/vis/vis.c
index 37956b100fad72257f5bab2b9f49908da59520cc..947456343125458845f26dc38b53f18d6fd42d75 100644
--- a/vis/vis.c
+++ b/vis/vis.c
@@ -27,6 +27,8 @@
 #include "netlink.h"
 #include "debugfs.h"
 
+#define IFACE_STATUS_LEN 256
+
 static struct globals vis_globals;
 
 struct vis_netlink_opts {
@@ -435,6 +437,131 @@ err_free_sock:
 	return err;
 }
 
+static int get_iface_status_netlink_parse(struct nl_msg *msg, void *arg)
+{
+	struct nlattr *attrs[NUM_BATADV_ATTR];
+	struct nlmsghdr *nlh = nlmsg_hdr(msg);
+	char *iface_status = arg;
+	struct genlmsghdr *ghdr;
+
+	if (!genlmsg_valid_hdr(nlh, 0))
+		return NL_OK;
+
+	ghdr = nlmsg_data(nlh);
+	if (ghdr->cmd != BATADV_CMD_GET_HARDIF)
+		return NL_OK;
+
+	if (nla_parse(attrs, BATADV_ATTR_MAX, genlmsg_attrdata(ghdr, 0),
+		      genlmsg_len(ghdr), batadv_netlink_policy))
+		return NL_OK;
+
+	if (attrs[BATADV_ATTR_ACTIVE])
+		strncpy(iface_status, "active\n", IFACE_STATUS_LEN);
+	else
+		strncpy(iface_status, "inactive\n", IFACE_STATUS_LEN);
+
+	iface_status[IFACE_STATUS_LEN - 1] = '\0';
+
+	return NL_STOP;
+}
+
+static char *get_iface_status_netlink(unsigned int meshif, unsigned int hardif,
+				      char *iface_status)
+{
+	char *ret_status = NULL;
+	struct nl_sock *sock;
+	struct nl_msg *msg;
+	int batadv_family;
+	struct nl_cb *cb;
+	int ret;
+
+	iface_status[0] = '\0';
+
+	sock = nl_socket_alloc();
+	if (!sock)
+		return NULL;
+
+	ret = genl_connect(sock);
+	if (ret < 0)
+		goto err_free_sock;
+
+	batadv_family = genl_ctrl_resolve(sock, BATADV_NL_NAME);
+	if (batadv_family < 0)
+		goto err_free_sock;
+
+	cb = nl_cb_alloc(NL_CB_DEFAULT);
+	if (!cb)
+		goto err_free_sock;
+
+	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, get_iface_status_netlink_parse,
+		iface_status);
+
+	msg = nlmsg_alloc();
+	if (!msg)
+		goto err_free_cb;
+
+	genlmsg_put(msg, NL_AUTO_PID, NL_AUTO_SEQ, batadv_family,
+		    0, 0, BATADV_CMD_GET_HARDIF, 1);
+
+	nla_put_u32(msg, BATADV_ATTR_MESH_IFINDEX, meshif);
+	nla_put_u32(msg, BATADV_ATTR_HARD_IFINDEX, hardif);
+
+	ret = nl_send_auto_complete(sock, msg);
+	if (ret < 0)
+		goto err_free_msg;
+
+	nl_recvmsgs(sock, cb);
+
+	if (strlen(iface_status) > 0)
+		ret_status = iface_status;
+
+err_free_msg:
+	nlmsg_free(msg);
+err_free_cb:
+	nl_cb_put(cb);
+err_free_sock:
+	nl_socket_free(sock);
+
+	return ret_status;
+}
+
+static bool interface_active(unsigned int meshif, unsigned int hardif,
+			     const char *ifname)
+{
+	char iface_status[IFACE_STATUS_LEN];
+	char path_buff[PATH_BUFF_LEN];
+	char *file_content = NULL;
+	char *content_newline;
+	bool active = false;
+	char *status;
+
+	status = get_iface_status_netlink(meshif, hardif, iface_status);
+	if (!status) {
+		snprintf(path_buff, sizeof(path_buff), SYS_IFACE_STATUS_FMT,
+			 ifname);
+		file_content = read_file(path_buff);
+		if (!file_content)
+			return false;
+
+		status = file_content;
+	}
+
+	content_newline = strstr(status, "\n");
+	if (content_newline)
+		*content_newline = '\0';
+
+	if (strcmp(status, "active") != 0)
+		goto free_file;
+
+	active = true;
+
+free_file:
+	free(file_content);
+	file_content = NULL;
+
+	return active;
+}
+
 struct register_interfaces_rtnl_arg {
 	struct globals *globals;
 	int ifindex;
@@ -449,10 +576,7 @@ 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;
@@ -476,23 +600,11 @@ static int register_interfaces_rtnl_parse(struct nl_msg *msg, void *arg)
 	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)
+	if (!interface_active(master, ifm->ifi_index, ifname))
 		goto err;
 
 	get_if_index_byname(register_arg->globals, ifname);
 
-free_file:
-	free(file_content);
-	file_content = NULL;
 err:
 	return NL_OK;
 }