if_indextoname.c 1.83 KB
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/*
 * Copyright (c) 2000-2002 University of Utah and the Flux Group.
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 * 
 * {{{EMULAB-LICENSE
 * 
 * This file is part of the Emulab network testbed software.
 * 
 * This file is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at
 * your option) any later version.
 * 
 * This file is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this file.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * }}}
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 */

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/* 
 * This is a very slightly modified version of
 * example code from Unix Netwok Programming, edition 2.
 */

#include "discvr.h"

#include <sys/sysctl.h>

char *
if_indextoname(unsigned int index, char *name)
{
	char				*buf, *next, *lim;
	size_t				len;
	struct if_msghdr	*ifm;
	struct sockaddr		*sa, *rti_info[RTAX_MAX];
	struct sockaddr_dl	*sdl;

	if ( (buf = net_rt_iflist(0, index, &len)) == NULL)
		return(NULL);

	lim = buf + len;
	for (next = buf; next < lim; next += ifm->ifm_msglen) {
		ifm = (struct if_msghdr *) next;
		if (ifm->ifm_type == RTM_IFINFO) {
			sa = (struct sockaddr *) (ifm + 1);
			get_rtaddrs(ifm->ifm_addrs, sa, rti_info);
			if ( (sa = rti_info[RTAX_IFP]) != NULL) {
				if (sa->sa_family == AF_LINK) {
					sdl = (struct sockaddr_dl *) sa;
					if (sdl->sdl_index == index) {
						strncpy(name, sdl->sdl_data, sdl->sdl_nlen);
						name[sdl->sdl_nlen] = 0;	/* null terminate */
						free(buf);
						return(name);
					}
				}
			}

		}
	}
	free(buf);
	return(NULL);		/* no match for index */
}