mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-20 11:11:24 +00:00
148 lines
3.0 KiB
C
148 lines
3.0 KiB
C
/*
|
|
* getif.c : get an interface structure
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/socket.h>
|
|
#include <sys/ioctl.h>
|
|
|
|
#if defined(SUNOS) || defined(SVR4)
|
|
#include <sys/sockio.h>
|
|
#endif
|
|
#ifdef SVR4
|
|
#include <sys/stropts.h>
|
|
#endif
|
|
|
|
#include <sys/time.h> /* for struct timeval in net/if.h */
|
|
#include <net/if.h> /* for struct ifreq */
|
|
#include <netinet/in.h>
|
|
|
|
#ifndef NO_UNISTD
|
|
#include <unistd.h>
|
|
#endif
|
|
#include <syslog.h>
|
|
#include <errno.h>
|
|
#include <assert.h>
|
|
|
|
#include "getif.h"
|
|
#include "report.h"
|
|
|
|
#ifdef __bsdi__
|
|
#define BSD 43
|
|
#endif
|
|
|
|
static struct ifreq ifreq[10]; /* Holds interface configuration */
|
|
static struct ifconf ifconf; /* points to ifreq */
|
|
|
|
static int nmatch();
|
|
|
|
/* Return a pointer to the interface struct for the passed address. */
|
|
struct ifreq *
|
|
getif(s, addrp)
|
|
int s; /* socket file descriptor */
|
|
struct in_addr *addrp; /* destination address on interface */
|
|
{
|
|
int maxmatch;
|
|
int len, m, incr;
|
|
struct ifreq *ifrq, *ifrmax;
|
|
struct sockaddr_in *sip;
|
|
char *p;
|
|
|
|
/* If no address was supplied, just return NULL. */
|
|
if (!addrp)
|
|
return (struct ifreq *) 0;
|
|
|
|
/* Get the interface config if not done already. */
|
|
if (ifconf.ifc_len == 0) {
|
|
#ifdef SVR4
|
|
/*
|
|
* SysVr4 returns garbage if you do this the obvious way!
|
|
* This one took a while to figure out... -gwr
|
|
*/
|
|
struct strioctl ioc;
|
|
ioc.ic_cmd = SIOCGIFCONF;
|
|
ioc.ic_timout = 0;
|
|
ioc.ic_len = sizeof(ifreq);
|
|
ioc.ic_dp = (char *) ifreq;
|
|
m = ioctl(s, I_STR, (char *) &ioc);
|
|
ifconf.ifc_len = ioc.ic_len;
|
|
ifconf.ifc_req = ifreq;
|
|
#else /* SVR4 */
|
|
ifconf.ifc_len = sizeof(ifreq);
|
|
ifconf.ifc_req = ifreq;
|
|
m = ioctl(s, SIOCGIFCONF, (caddr_t) & ifconf);
|
|
#endif /* SVR4 */
|
|
if ((m < 0) || (ifconf.ifc_len <= 0)) {
|
|
report(LOG_ERR, "ioctl SIOCGIFCONF");
|
|
return (struct ifreq *) 0;
|
|
}
|
|
}
|
|
maxmatch = 7; /* this many bits or less... */
|
|
ifrmax = (struct ifreq *) 0;/* ... is not a valid match */
|
|
p = (char *) ifreq;
|
|
len = ifconf.ifc_len;
|
|
while (len > 0) {
|
|
ifrq = (struct ifreq *) p;
|
|
sip = (struct sockaddr_in *) &ifrq->ifr_addr;
|
|
m = nmatch(addrp, &(sip->sin_addr));
|
|
if (m > maxmatch) {
|
|
maxmatch = m;
|
|
ifrmax = ifrq;
|
|
}
|
|
#ifndef IFNAMSIZ
|
|
/* BSD not defined or earlier than 4.3 */
|
|
incr = sizeof(*ifrq);
|
|
#else
|
|
incr = ifrq->ifr_addr.sa_len + IFNAMSIZ;
|
|
#endif
|
|
|
|
p += incr;
|
|
len -= incr;
|
|
}
|
|
|
|
return ifrmax;
|
|
}
|
|
|
|
/*
|
|
* Return the number of leading bits matching in the
|
|
* internet addresses supplied.
|
|
*/
|
|
static int
|
|
nmatch(ca, cb)
|
|
u_char *ca, *cb; /* ptrs to IP address, network order */
|
|
{
|
|
u_int m = 0; /* count of matching bits */
|
|
u_int n = 4; /* bytes left, then bitmask */
|
|
|
|
/* Count matching bytes. */
|
|
while (n && (*ca == *cb)) {
|
|
ca++;
|
|
cb++;
|
|
m += 8;
|
|
n--;
|
|
}
|
|
/* Now count matching bits. */
|
|
if (n) {
|
|
n = 0x80;
|
|
while (n && ((*ca & n) == (*cb & n))) {
|
|
m++;
|
|
n >>= 1;
|
|
}
|
|
}
|
|
return (m);
|
|
}
|
|
|
|
/*
|
|
* Local Variables:
|
|
* tab-width: 4
|
|
* c-indent-level: 4
|
|
* c-argdecl-indent: 4
|
|
* c-continued-statement-offset: 4
|
|
* c-continued-brace-offset: -4
|
|
* c-label-offset: -4
|
|
* c-brace-offset: 0
|
|
* End:
|
|
*/
|