[PATCH] net-tools 1.60: deferred ifconfig netmask

Malita, Florin florin.malita at glenayre.com
Wed Sep 1 17:13:18 UTC 2004


This has been around for too long:

        [root at scox root]# ifconfig eth0:1 192.168.120.12/22
        SIOCSIFNETMASK: Cannot assign requested address
        [root at scox root]# ifconfig eth0:1 192.168.120.12/22
        [root at scox root]#

First time it fails to assign the specified netmask apparently because
it is attempting to do so _before_ assigning the address. Second time it
succeeds as the interface already has an address.

OTOH: 
        [root at scox root]# ifconfig eth0:1 192.168.120.12 netmask
        255.255.252.0
        [root at scox root]#

succeeds the first time since the actions are executed in the right
order: SIOCSIFADDR _then_ SIOCSIFNETMASK.

This patch against net-tools-1.60 defers the netmask ioctl when using
implicit/CIDR notation till after the address has been assigned. IOW, it
makes the 2 commands equivalent (as some of us might expect ;).

-- 
Florin Malita <florin.malita at glenayre.com>


diff -aur net-tools-1.60.orig/ifconfig.c net-tools-1.60.new/ifconfig.c
--- net-tools-1.60.orig/ifconfig.c      2001-04-13 14:25:18.000000000
-0400
+++ net-tools-1.60.new/ifconfig.c       2004-08-31 17:07:38.362758712
-0400
@@ -23,6 +23,7 @@
  *         20001008 - Bernd Eckenfels, Patch from RH for setting mtu
  *                     (default AF was wrong)
  *          20010404 - Arnaldo Carvalho de Melo, use setlocale
+ *          20040831 - Florin Malita <fmalita at glenayre.com> delayed
CIDR netmask
  */    
           
#define DFLT_AF "inet"
@@ -227,13 +228,13 @@

int main(int argc, char **argv)
{              
-    struct sockaddr sa;
+    struct sockaddr sa, sa_netmask;
     struct sockaddr_in sin;
     char host[128];
     struct aftype *ap;
     struct hwtype *hw;
     struct ifreq ifr;
-    int goterr = 0, didnetmask = 0;
+    int goterr = 0, didnetmask = 0, donetmask = 0;
     char **spp;
     int fd;    
#if HAVE_AFINET6
@@ -903,16 +904,16 @@
        /* FIXME: sa is too small for INET6 addresses, inet6 should use
that too,
           broadcast is unexpected */
        if (ap->getmask) {
-           switch (ap->getmask(host, &sa, NULL)) {
+           switch (ap->getmask(host, &sa_netmask, NULL)) {
            case -1:
                usage();
                break;
            case 1:
                if (didnetmask)
                    usage();
-       
-               goterr = set_netmask(skfd, &ifr, &sa);
-               didnetmask++;
+               
+               /* delay setting the CIDR netmask till after setting the
addr */
+               donetmask = 1;
                break;
            }
        }
@@ -960,6 +961,13 @@
            }
        }

+       /* set CIDR netmask */
+       if (donetmask){
+           donetmask = 0;
+           goterr = set_netmask(skfd, &ifr, &sa_netmask);
+           didnetmask++;
+       }
+
        /*
         * Don't do the set_flag() if the address is an alias with a -
at the
         * end, since it's deleted already! - Roman
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