[bug-inetutils] Re: ifconfig -a on linux x86-64 + glibc

[Chris Webb]

Chris Webb <address@hidden> writes:

> I'm having trouble with the ifconfig shipped with GNU inetutils 1.8 on
> x86-64 linux with glibc 2.11.1. Building and running it (either with or
> without -a) only ever gives information for the loopback interface, although
> running it in the form 'ifconfig eth0' will correctly give info for the eth0
> interface.

I've done some debugging on this. The code in if_nameindex() is a bit strange.
I have no idea why it is doing something like

  ifr = (struct ifreq *) ((caddr_t) ifr + len + IFNAMSIZ);

(which doesn't work) rather than ifr++ (which does). Perhaps some portability
issue on another platform? I include a patch below to fix and tidy up this
function, assuming this is just a relic.

There remains a second bug with inetutils ifconfig on linux: ifconfig only
displays active interfaces, whether or not -a is given. As far as I can see,
SIOCGIFCONF is only returning active interfaces. I'll take a look at that next.

-- 8< --
From: Chris Webb <address@hidden>
Date: Thu, 1 Jul 2010 10:50:32 +0100
Subject: [PATCH] Fix if_nameindex() in ifconfig on linux/x86-64

This makes ifconfig [-a] work correctly on 64-bit linux, and possibly other
64-bit platforms too.

Signed-off-by: Chris Webb <address@hidden>

diff --git a/ifconfig/if_index.c b/ifconfig/if_index.c
index 199904c..6b734be 100644
--- a/ifconfig/if_index.c
+++ b/ifconfig/if_index.c
@@ -132,22 +132,8 @@ if_nameindex (void)
   end = (struct ifreq *) ((caddr_t) ifr + ifc.ifc_len);
   while (ifr < end)
     {
-      int len;
-# ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
-#  undef MAX
-#  define MAX(a,b)  (((a) > (b)) ? (a) : (b))
-      len = MAX (sizeof (struct sockaddr), ifr->ifr_addr.sa_len);
-# else
-      len = sizeof (struct sockaddr);
-# endif
-
-      cur = ifr;
-
-      /* Step along the array by the size of the current structure */
-      ifr = (struct ifreq *) ((caddr_t) ifr + len + IFNAMSIZ);
-
       /* We ignore the other families .. OK ?  */
-      if (cur->ifr_addr.sa_family != AF_INET)
+      if (ifr->ifr_addr.sa_family != AF_INET)
        continue;
 
       /* Make Room safely.  */
@@ -166,7 +152,7 @@ if_nameindex (void)
 
       /* FIXME: We did not deal with duplicates or interface aliases.  */
 
-      idx[i].if_name = strdup (cur->ifr_name);
+      idx[i].if_name = strdup (ifr->ifr_name);
       if (idx[i].if_name == NULL)
        {
          if_freenameindex (idx);
@@ -176,12 +162,13 @@ if_nameindex (void)
        }
 
 # if defined(SIOCGIFINDEX)
-      if (ioctl (fd, SIOCGIFINDEX, cur) >= 0)
-       idx[i].if_index = cur->ifr_index;
+      if (ioctl (fd, SIOCGIFINDEX, ifr) >= 0)
+       idx[i].if_index = ifr->ifr_index;
       else
 # endif
        idx[i].if_index = i + 1;
       i++;
+      ifr++;
     }
 
   /* Terminate the array with an empty solt.  */