2 * getif.c : get an interface structure
4 * $FreeBSD: src/libexec/bootpd/getif.c,v 1.7 1999/08/28 00:09:18 peter Exp $
5 * $DragonFly: src/libexec/bootpd/getif.c,v 1.2 2003/06/17 04:27:07 dillon Exp $
9 #include <sys/socket.h>
10 #include <sys/ioctl.h>
12 #if defined(SUNOS) || defined(SVR4)
13 #include <sys/sockio.h>
16 #include <sys/stropts.h>
19 #include <sys/time.h> /* for struct timeval in net/if.h */
20 #include <net/if.h> /* for struct ifreq */
21 #include <netinet/in.h>
37 static struct ifreq ifreq[10]; /* Holds interface configuration */
38 static struct ifconf ifconf; /* points to ifreq */
42 /* Return a pointer to the interface struct for the passed address. */
45 int s; /* socket file descriptor */
46 struct in_addr *addrp; /* destination address on interface */
50 struct ifreq *ifrq, *ifrmax;
51 struct sockaddr_in *sip;
54 /* If no address was supplied, just return NULL. */
56 return (struct ifreq *) 0;
58 /* Get the interface config if not done already. */
59 if (ifconf.ifc_len == 0) {
62 * SysVr4 returns garbage if you do this the obvious way!
63 * This one took a while to figure out... -gwr
66 ioc.ic_cmd = SIOCGIFCONF;
68 ioc.ic_len = sizeof(ifreq);
69 ioc.ic_dp = (char *) ifreq;
70 m = ioctl(s, I_STR, (char *) &ioc);
71 ifconf.ifc_len = ioc.ic_len;
72 ifconf.ifc_req = ifreq;
74 ifconf.ifc_len = sizeof(ifreq);
75 ifconf.ifc_req = ifreq;
76 m = ioctl(s, SIOCGIFCONF, (caddr_t) & ifconf);
78 if ((m < 0) || (ifconf.ifc_len <= 0)) {
79 report(LOG_ERR, "ioctl SIOCGIFCONF");
80 return (struct ifreq *) 0;
83 maxmatch = 7; /* this many bits or less... */
84 ifrmax = (struct ifreq *) 0;/* ... is not a valid match */
88 ifrq = (struct ifreq *) p;
89 sip = (struct sockaddr_in *) &ifrq->ifr_addr;
90 m = nmatch(addrp, &(sip->sin_addr));
96 /* BSD not defined or earlier than 4.3 */
99 incr = ifrq->ifr_addr.sa_len + IFNAMSIZ;
110 * Return the number of leading bits matching in the
111 * internet addresses supplied.
115 u_char *ca, *cb; /* ptrs to IP address, network order */
117 u_int m = 0; /* count of matching bits */
118 u_int n = 4; /* bytes left, then bitmask */
120 /* Count matching bytes. */
121 while (n && (*ca == *cb)) {
127 /* Now count matching bits. */
130 while (n && ((*ca & n) == (*cb & n))) {
142 * c-argdecl-indent: 4
143 * c-continued-statement-offset: 4
144 * c-continued-brace-offset: -4