netstat fix

[Michael Tuexen]

Dear all,

netstat -bi currently shows on one of my systems something like:

Name    Mtu Network       Address              Ipkts Ierrs Idrop     Ibytes    Opkts Oerrs     Obytes  Coll
ix0    9000 <Link#1>      00:1b:21:55:1e:b8        0     0     0          0        0     0          0     0
ix0    9000 10.16.0.0     10.16.0.5                0     -     -          0        0     -          0     -
ix0    9000 fe80::21b:21f fe80::21b:21ff:fe        0     -     -          0        2     -        152     -
...
usbus     0 <Link#18>                              0     0     0          0        0     0          0     0
fwip0  1500 <Link#19>     00:30:05:b3:50:0b:40:e4:0a:02:ff:fe:00:00:00:00        0     0     0          0        0     0          0     0
fwe0*  1500 <Link#20>     02:30:05:0b:40:e4        0     0     0          0        0     0          0     0

The point here is that for one row the entry in the Address column is not limited to 17 characters
as it is in all other cases. The following patch fixes this:

Index: usr.bin/netstat/if.c
===================================================================
--- usr.bin/netstat/if.c	(revision 221601)
+++ usr.bin/netstat/if.c	(working copy)
@@ -394,7 +394,7 @@
 				n = cp - sa->sa_data + 1;
 				cp = sa->sa_data;
 			hexprint:
-				while (--n >= 0)
+				while ((--n >= 0) && (m < 30))
 					m += printf("%02x%c", *cp++ & 0xff,
 						    n > 0 ? ':' : ' ');
 				m = 32 - m;

The current code does not enforce any limit on the length of AF_LINK
addresses (and the ones which are not handled specifically with netstat).
All other addresses are truncated (see the IPv6 addresses above).

With the patch the above output is:

Name    Mtu Network       Address              Ipkts Ierrs Idrop     Ibytes    Opkts Oerrs     Obytes  Coll
ix0    9000 <Link#1>      00:1b:21:55:1e:b8        0     0     0          0        0     0          0     0
ix0    9000 10.16.0.0     10.16.0.5                0     -     -          0        0     -          0     -
ix0    9000 fe80::21b:21f fe80::21b:21ff:fe        0     -     -          0        2     -        152     -
...
usbus     0 <Link#18>                              0     0     0          0        0     0          0     0
fwip0  1500 <Link#19>     00:30:05:b3:50:0b:       0     0     0          0        0     0          0     0
fwe0*  1500 <Link#20>     02:30:05:0b:40:e4        0     0     0          0        0     0          0     0

Any objections against committing the patch? Or suggestions?

Best regards
Michael