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/*
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char rcsid[] =
"@(#)$Header: inet.c,v 1.12 92/01/29 12:46:18 mccanne Exp $ (LBL)";
#endif
#include <stdio.h>
#include <ctype.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
#include "interface.h"
/* Not all systems have IFF_LOOPBACK */
#ifdef IFF_LOOPBACK
#define ISLOOPBACK(p) ((p)->ifr_flags & IFF_LOOPBACK)
#else
#define ISLOOPBACK(p) (strcmp((p)->ifr_name, "lo0") == 0)
#endif
/*
* Return the name of a network interface attached to the system, or 0
* if none can be found. The interface must be configured up; the
* lowest unit number is preferred; loopback is ignored.
*/
char *
lookup_device()
{
struct ifreq ibuf[16], *ifrp, *ifend, *mp;
struct ifconf ifc;
int fd;
int minunit, n;
char *cp;
static char device[sizeof(ifrp->ifr_name)];
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd < 0) {
perror("tcpdump: socket");
exit(1);
}
ifc.ifc_len = sizeof ibuf;
ifc.ifc_buf = (caddr_t)ibuf;
if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
ifc.ifc_len < sizeof(struct ifreq)) {
perror("tcpdump: SIOCGIFCONF: ");
exit(1);
}
ifrp = ibuf;
ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
mp = 0;
minunit = 666;
while (ifrp < ifend) {
struct ifreq ifr;
/*
* Need a template to preserve address info that is
* used below to locate the next entry. (Otherwise,
* SIOCGIFFLAGS stomps over it because the requests
* are returned in a union.)
*/
bcopy(ifrp->ifr_name, ifr.ifr_name, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
fprintf(stderr, "tcpdump: SIOCGIFFLAGS: ");
perror(ifrp->ifr_name);
exit(1);
}
if ((ifr.ifr_flags & IFF_UP) && !ISLOOPBACK(&ifr)) {
for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
;
n = atoi(cp);
if (n < minunit) {
minunit = n;
mp = ifrp;
}
}
#if BSD >= 199006
n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
if (n < sizeof(*ifrp))
++ifrp;
else
ifrp = (struct ifreq *)((char *)ifrp + n);
#else
++ifrp;
#endif
}
close(fd);
if (mp == 0)
return (0);
(void)strcpy(device, mp->ifr_name);
return (device);
}
/*
* Get the netmask of an IP address. This routine is used if
* SIOCGIFNETMASK doesn't work.
*/
static u_long
ipaddrtonetmask(addr)
u_long addr;
{
if (IN_CLASSA(addr))
return (IN_CLASSA_NET);
if (IN_CLASSB(addr))
return (IN_CLASSB_NET);
if (IN_CLASSC(addr))
return (IN_CLASSC_NET);
error("unknown IP address class: %08X", addr);
/* NOTREACHED */
}
void
lookup_net(device, netp, maskp)
char *device;
u_long *netp;
u_long *maskp;
{
int fd;
struct ifreq ifr;
struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;
/* Use data gram socket to get IP address. */
if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror("tcpdump: socket");
exit(1);
}
(void)strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name);
if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
/*
* This will fail if an IP address hasn't been assigned.
*/
*netp = 0;
*maskp = 0;
return;
}
*netp = sin->sin_addr.s_addr;
if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0)
*maskp = 0;
else
*maskp = sin->sin_addr.s_addr;
if (*maskp == 0)
*maskp = ipaddrtonetmask(*netp);
*netp &= *maskp;
(void)close(fd);
}
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