Plugin: openvpn

[faxm0dem]

• Version of collectd: master
• Operating system / distribution: debian buster

Expected behavior

openvpn plugin should work even if it was configured not to assign ipv6 address

Actual behavior

It's failing with:

openvpn plugin: File format error in instance openvpn-status.log: Fields count mismatch.

Upon further investigation it appears that fields_num is 11 and columns 12 in openvpn.c line 376

Steps to reproduce

Configure openvpn so that ipv6 is empty

Here's an example status line:

TIME,Mon Mar 16 17:47:15 2020,1584377235
HEADER,CLIENT_LIST,Common Name,Real Address,Virtual Address,Virtual IPv6 Address,Bytes Received,Bytes Sent,Connected Since,Connected Since (time_t),Username,Client ID,Peer ID
CLIENT_LIST,jon-doe,1.2.3.4:50226,2.3.4.5,,105054404,148706903,Mon Mar 16 16:37:25 2020,1584373045,UNDEF,2145,0
HEADER,ROUTING_TABLE,Virtual Address,Common Name,Real Address,Last Ref,Last Ref (time_t)
ROUTING_TABLE,ff:ff:ff:ff:ff:ff,jon-doe,3.4.5.6:50226,Mon Mar 16 17:47:14 2020,1584377234
GLOBAL_STATS,Max bcast/mcast queue length,140
END

[faxm0dem]

okay so the root cause is because strtok_r "skips" empty fields. From its manpage:

    From the above description, it follows that a sequence of  two  or  more
   contiguous  delimiter  bytes  in the parsed string is considered to be a
   single delimiter, and that delimiter bytes at the start or  end  of  the
   string  are  ignored.   Put another way: the tokens returned by strtok()
   are always nonempty  strings.   Thus,  for  example,  given  the  string
   "aaa;;bbb,",  successive  calls  to  strtok() that specify the delimiter
   string ";," would return the strings "aaa" and "bbb", and  then  a  null
   pointer.

[faxm0dem]

it appears it's possible to use this trick, although it uses strtok and not strtok_r: https://stackoverflow.com/a/18827736/2122722

I would rather use strstep instead, but that might break other unices. Ideas?

[rpv-tomsk]

Hi,

Stay tuned, WIP.

[faxm0dem]

I tested this:

static int openvpn_strsplit(char *string, char **fields, size_t size) {
  size_t i = 0;
  char *ptr = string;

  while ((fields[i] = strsep(&ptr, ",\t")) != NULL) {
    i++;

    if (i >= size)
      break;
  }

  return i;
} /* int openvpn_strsplit */

[rpv-tomsk]

Added #3425

[faxm0dem]

is strsep available on solaris/AIX/etc.?

[dago]

Not on older releases: https://www.gnu.org/software/gnulib/manual/html_node/strsep.html