[B.A.T.M.A.N.] [PATCH next 3/3] batctl: add sys framework for VLAN support

[Antonio Quartulli <antonio@meshcoding.com>]

From: Marco Dalla Torre <marco.dallato@gmail.com>

Allow the batctl tool to take advantage of changes from commit
e4ff5c153dab054a6cd1c4132f87bc5e77127456 "add sys framework for VLAN"
recently added to batman-adv, so that users can execute commands in
a per VLAN fashion.

If no directory entry corresponding to the user-selected device is found
at the standard location for non VLAN interfaces
(/sys/class/net/${device}/mesh/), 'batctl' now looks into directory:
     /sys/class/net/${base_device}/mesh/vlan${vid}
Information on VLAN devices (base device, vid) necessary to construct the
directory path is acquired by querying the netlink kernel module.
Where:
    -${base_device}: the batman device on top of which the VLAN is sitting
    -${device}: the device interface for the VLAN,
    -${vid}: the identifier assigned to the VLAN.

If the user-selected command is not supported by the VLAN, an appropriate
error is shown.

Signed-off-by: Marco Dalla Torre <marco.dallato@gmail.com>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
---
 functions.c  |  3 +++
 main.c       |  2 +-
 man/batctl.8 |  4 ++--
 sys.c        | 49 ++++++++++++++++++++++++++++++++++++++++++++++++-
 sys.h        | 22 ++++++++++++----------
 5 files changed, 66 insertions(+), 14 deletions(-)

diff --git a/functions.c b/functions.c
index 4934675..7993c83 100644
--- a/functions.c
+++ b/functions.c
@@ -143,6 +143,9 @@ static void file_open_problem_dbg(const char *dir, const char *fname,
 			fprintf(stderr, "Error - the folder '/sys/' was not found on the system\n");
 			fprintf(stderr, "Please make sure that the sys filesystem is properly mounted\n");
 			return;
+		} else if (strstr(dir, "/sys/devices/virtual/")) {
+			fprintf(stderr, "The selected feature '%s' is not supported for vlans\n", fname);
+			return;
 		}
 	}
 
diff --git a/main.c b/main.c
index aab2e11..843fbc4 100644
--- a/main.c
+++ b/main.c
@@ -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 mesh-based VLAN 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");
diff --git a/man/batctl.8 b/man/batctl.8
index fafe735..95e887d 100644
--- a/man/batctl.8
+++ b/man/batctl.8
@@ -42,7 +42,7 @@ behaviour or using the B.A.T.M.A.N. advanced protocol.
 .SH OPTIONS
 .TP
 .I \fBoptions:
-\-m     specify mesh interface (default 'bat0')
+\-m     specify mesh interface or a mesh-based VLAN interface (default 'bat0')
 .br
 \-h     print general batctl help
 .br
@@ -61,7 +61,7 @@ originator interval. The interval is in units of milliseconds.
 .br
 .IP "\fBap_isolation\fP|\fBap\fP [\fB0\fP|\fB1\fP]"
 If no parameter is given the current ap isolation setting is displayed. Otherwise the parameter is used to enable or
-disable ap isolation.
+disable ap isolation. This command can be used in conjunction with "-m" option to target per VLAN configurations.
 .br
 .IP "\fBbridge_loop_avoidance\fP|\fBbl\fP [\fB0\fP|\fB1\fP]"
 If no parameter is given the current bridge loop avoidance setting is displayed. Otherwise the parameter is used to enable
diff --git a/sys.c b/sys.c
index 2a508e2..6424678 100644
--- a/sys.c
+++ b/sys.c
@@ -372,9 +372,11 @@ static void settings_usage(int setting)
 
 int handle_sys_setting(char *mesh_iface, int setting, int argc, char **argv)
 {
-	int optchar, res = EXIT_FAILURE;
+	int vid = -1, optchar, res = EXIT_FAILURE;
 	char *path_buff;
 	const char **ptr;
+	char *base_dev;
+	ssize_t path_length;
 
 	while ((optchar = getopt(argc, argv, "h")) != -1) {
 		switch (optchar) {
@@ -391,6 +393,51 @@ int handle_sys_setting(char *mesh_iface, int setting, int argc, char **argv)
 	snprintf(path_buff, PATH_BUFF_LEN, SYS_BATIF_PATH_FMT, mesh_iface);
 	path_buff[PATH_BUFF_LEN - 1] = '\0';
 
+check_path:
+	if (access(path_buff, F_OK) != 0) {
+		/* if vid is valid it means that we have already looked for a
+		 * vlan, but the interface we found is not a valid batman-adv
+		 * interface
+		 */
+		if (vid >= 0) {
+			fprintf(stderr, "Not a valid batman-adv interface: %s\n",
+				base_dev);
+			return EXIT_FAILURE;
+		}
+
+		if (errno == ENOENT) {
+			/* path does not exist, no lan interface: check vlan */
+			vid = vlan_get_link(mesh_iface, &base_dev);
+			if (vid < 0)
+				return EXIT_FAILURE;
+
+			snprintf(path_buff, PATH_BUFF_LEN, SYS_BATIF_PATH_FMT,
+				 base_dev);
+
+			goto check_path;
+		} else if (errno == ENOTDIR) {
+			/* not a directory, something wrong here */
+			fprintf(stderr, "Error - expected directory at '%s'\n",
+				path_buff);
+			return EXIT_FAILURE;
+		}
+	}
+
+	/* if we are in a vlan realm we have to update the path before accessing
+	 * the attributes
+	 */
+	if (vid >= 0) {
+		path_length = strlen(SYS_VLAN_PATH) + strlen(base_dev) +
+			      VLAN_ID_MAX_LEN + 1;
+		path_buff = realloc(path_buff, path_length);
+		if (!path_buff) {
+			fprintf(stderr,
+				"Error - could not allocate path buffer: out of memory ?\n");
+			return EXIT_FAILURE;
+		}
+		snprintf(path_buff, path_length, SYS_VLAN_PATH, base_dev, vid);
+	}
+
 	if (argc == 1) {
 		res = read_file(path_buff, (char *)batctl_settings[setting].sysfs_name,
 				NO_FLAGS, 0, 0, 0);
diff --git a/sys.h b/sys.h
index 8934978..2cbbcfb 100644
--- a/sys.h
+++ b/sys.h
@@ -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,
-- 
1.8.5.2