[B.A.T.M.A.N.] [RFC] batctl update to use the sys framework for VLAN

[Marco Dalla Torre <marco.dallato@gmail.com>]

Hello list,

The following is a small patch proposal to allow the batctl tool to use 
the sys framework for VLAN recently added to  batman-adv, so that 
commands can be applied in a per VLAN fashion at user discretion. 
Comments and suggestions are extremely welcome.



If no directory entry corresponding to the user-selected device is found 
at the
standard location for non VLAN interfaces (/sys/class/net/${base_device}),
'batctl' now looks into directory:
      /sys/devices/virtual/net/${base_device}/mesh/vlan${vid}
Where:
     -${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.

Information on VLAN devices (base device, vid) is acquired by parsing
/proc/net/vlan/${device}.

If the user-selected command is not supported by the VLAN, an appropriate
error is shown.
---
  functions.c |  7 ++++++-
  sys.c       | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/functions.c b/functions.c
index cc05a48..973b6f8 100644
--- a/functions.c
+++ b/functions.c
@@ -135,8 +135,13 @@ static void file_open_problem_dbg(char *dir, char 
*fname, char *full_path)
              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;
          }
-    }
+    }
+
+

      if (!file_exists(module_ver_path)) {
          fprintf(stderr, "Error - batman-adv module has not been 
loaded\n");
diff --git a/sys.c b/sys.c
index b1d7ea8..799f275 100644
--- a/sys.c
+++ b/sys.c
@@ -371,6 +371,39 @@ static void settings_usage(int setting)
      fprintf(stderr, " \t -h print this help\n");
  }

+int get_basedev_vid(char *mesh_iface, char **base_dev, unsigned short *vid)
+{
+    char *vdev;
+    char line[100];
+    const char path[]="/proc/net/vlan/";
+    int size=sizeof(path)+sizeof(mesh_iface);
+    FILE *fp = NULL;
+
+    char *fpath=malloc(size);
+    strcpy(fpath, path);
+    /* prepare path file path: /proc/net/vlan/$mesh_iface*/
+    strcat(fpath, mesh_iface);
+
+    fp = fopen(fpath, "r");
+    if (fp == NULL) {
+        return 1;
+    }
+
+    if (fscanf(fp, "%ms %*s %hu %*s %*d %*s %*d", &vdev, vid)==0) {
+        return 0;
+    }
+    while (fgets(line, sizeof(line), fp) != NULL) {
+        if (sscanf(line, "Device: %ms", base_dev) == 1) {
+            break;
+        }
+    }
+    // handle base device not found case
+    if (*base_dev==NULL) {
+        return 0;
+    }
+    return 1;
+}
+
  int handle_sys_setting(char *mesh_iface, int setting, int argc, char 
**argv)
  {
      int optchar, res = EXIT_FAILURE;
@@ -392,6 +425,27 @@ 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';

+    if (access(path_buff, F_OK) != 0) {
+        if (errno == ENOENT) {
+            // does not exist, no lan interface: check vlan
+            unsigned short vid=0;
+            char *base_dev=NULL;
+            if (get_basedev_vid(mesh_iface, &base_dev, &vid) == 1) {
+                free(path_buff);
+                char 
sys_vlan_path[]="/sys/devices/virtual/net/%s/mesh/vlan%d/";
+                int size=sizeof(sys_vlan_path)+sizeof(base_dev);
+                path_buff=malloc(size);
+                sprintf(path_buff, sys_vlan_path, base_dev, vid);
+            }
+        }
+        if (errno == ENOTDIR) {
+            // not a directory, something wrong here
+            fprintf(stderr, "Error - expected directory at '%s'\n",
+                path_buff);
+            return EXIT_FAILURE;
+        }
+    }
+
      if (argc == 1) {
          res = read_file(path_buff, (char 
*)batctl_settings[setting].sysfs_name,
                  NO_FLAGS, 0, 0, 0);
-- 
1.8.3.2