Return to BSD News archive
Path: sserve!manuel!munnari.oz.au!spool.mu.edu!yale.edu!qt.cs.utexas.edu!news.Brown.EDU!noc.near.net!uunet!vtserf!GroupW.cns.vt.edu!linkt
From: linkt@GroupW.cns.vt.edu (Tim Link)
Newsgroups: comp.unix.bsd
Subject: getting net config with SIOCGIFCONF ioctl call
Keywords: ioctl ifconf ifreq
Message-ID: <7519@vtserf.cc.vt.edu>
Date: 29 Sep 92 05:19:30 GMT
Sender: usenet@vtserf.cc.vt.edu
Followup-To: linkt@Groupw.CNS.VT.EDU
Organization: Va Tech Communications Resources
Lines: 94
I'm working on a program that needs to determine the network
configuration under 386BSD. I'm using the SIOCGIFCONF IOCTL function
which *I THINK* should return to me an array of ifreq structures which
have the name of the interface and it's ip address. This ain't what I'm
gettin'. I've poked and prodded and looked at if.c to try to figure out
what's going on, but I can't see where the problem is. Just as a test I
compiled the program on an Ultrix machine and the results were close to
what I expected, but still not exact. Can anybody look at this and tell
me if I'm completely wrong in what I'm doing of if SIOCGIFCONF isn't
returning what it should be???
As always, any and all help appreciated.
Tim
Here's the output with 386BSD:
(The addresses are completely wrong, and why are the "if" names
spaced?)
if:we0 addr:0.3.0.0
if: addr:4.5.0.0
if: addr:12.3.45.35
if: addr:7.0.0.1
if: addr:0.0.3.0
if: addr:0.0.0.0
if:sl0 addr:24.0.0.2
if: addr:0.0.0.0
if: addr:0.0.0.0
if: addr:0.0.0.0
Here's the output on the Ultrix system:
if:ln0 addr:0.0.0.0 <---+-- What are these???
if:ln0 addr:4.5.0.2 <---+
if:ln0 addr:128.173.5.9<-----+- These are correct.
if:lo0 addr:127.0.0.1 <-----+
if: addr:0.0.0.0
if: addr:0.0.0.0
if: addr:0.0.0.0
if: addr:0.0.0.0
if: addr:0.0.0.0
if: addr:0.0.0.0
And here's the program:
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdio.h>
struct ifreq ifreq[10]; /* Holds interface configuration */
struct ifconf ifconf; /* Int. config ioctl block (pnts to ifreq) */
int s;
int i, y;
struct in_addr ipa;
struct ifreq iftest;
struct in_addr test2;
main()
{
printf("\n");
/*
* Get a socket.
*/
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
printf( "socket error\n" );
exit(1);
}
/*
* Get network configuration.
*/
ifconf.ifc_len = sizeof(ifreq);
ifconf.ifc_req = ifreq;
if ((ioctl(s, SIOCGIFCONF, (caddr_t) &ifconf) < 0) ||
(ifconf.ifc_len <= 0)) {
printf("ioctl error\n");
exit(1);
}
printf( "\n" );
for ( i = 0; i < 10; i++ ) {
printf( "if:%s \t addr:%s\n", &ifreq[i].ifr_name,
inet_ntoa( ((struct sockaddr_in *)(&ifreq[i].ifr_addr))->sin_addr ) );
}
}
QUIT
name,
inet_ntoa( ((struct sockaddr_in *)(&ifreq[i].ifr_addr))->sin_addr ) );
}
}