Iptables input plugins skips lines with empty target and "port" column

[lberruti]

Bug report

Iptables input plugin skips lines with empty target and "port" column

Relevant telegraf.conf:

[[inputs.iptables]]
   use_sudo = true
   table = "filter"
   chains = [ "accountfwd" ]

System info:

Telegraf 1.4.0-1 (telegraf_1.4.0-1_i386.deb), Debian 8.9

Steps to reproduce:

Having this rules:

# /sbin/iptables -nvL accountfwd -t filter -x
Chain accountfwd (1 references)
    pkts      bytes target     prot opt in     out     source               destination
32540119 10615137679            all  --  eth0   *       0.0.0.0/0            0.0.0.0/0            /* all_recv */
22882685 36949730032            all  --  *      eth0    0.0.0.0/0            0.0.0.0/0            /* all_sent */
     874   125870            tcp  --  eth0   *       0.0.0.0/0            66.177.8.49          multiport dports 80,443 /* serv_recv */
  352509 465079508            tcp  --  eth0   *       0.0.0.0/0            66.177.8.49          multiport dports 25,465,587 /* serv_recv */
  335261 22742238 RETURN     all  --  eth0   eth4    0.0.0.0/0            0.0.0.0/0            /* serv2_recv */
  379155 61104334 RETURN     all  --  eth4   eth0    0.0.0.0/0            0.0.0.0/0            /* serv2_sent */

then run:

telegraf --config telegraf.conf --input-filter iptables --test

Expected behavior:

All lines are parsed:

iptables,table=filter,chain=accountfwd,ruleid=all_recv pkts=32540119i,bytes=10615137679i 1505397710000000000
iptables,table=filter,chain=accountfwd,ruleid=all_sent pkts=22882685i,bytes=36949730032i 1505397710000000000
iptables,table=filter,chain=accountfwd,ruleid=serv_recv pkts=874i,bytes=125870i 1505397710000000000
iptables,chain=accountfwd,ruleid=serv_recv,table=filter pkts=352509i,bytes=465079508i 1505397710000000000
iptables,table=filter,chain=accountfwd,ruleid=serv2_recv pkts=335261i,bytes=22742238i 1505397710000000000
iptables,chain=accountfwd,ruleid=serv2_recv,table=filter pkts=379155i,bytes=61104334i 1505397710000000000

Actual behavior:

Lines with empty "target" and empty "port" column are skipped

iptables,table=filter,chain=accountfwd,ruleid=serv_recv pkts=874i,bytes=125870i 1505397710000000000
iptables,chain=accountfwd,ruleid=serv_recv,table=filter pkts=352509i,bytes=465079508i 1505397710000000000
iptables,table=filter,chain=accountfwd,ruleid=serv2_recv pkts=335261i,bytes=22742238i 1505397710000000000
iptables,chain=accountfwd,ruleid=serv2_recv,table=filter pkts=379155i,bytes=61104334i 1505397710000000000

Additional info:

Telegraf 1.3.5-1 works as expected