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 */
43 * Return a pointer to the interface struct for the passed address.
45 * s socket file descriptor
46 * addrp destination address on interface
49 getif(int s, struct in_addr *addrp)
53 struct ifreq *ifrq, *ifrmax;
54 struct sockaddr_in *sip;
57 /* If no address was supplied, just return NULL. */
59 return (struct ifreq *) 0;
61 /* Get the interface config if not done already. */
62 if (ifconf.ifc_len == 0) {
65 * SysVr4 returns garbage if you do this the obvious way!
66 * This one took a while to figure out... -gwr
69 ioc.ic_cmd = SIOCGIFCONF;
71 ioc.ic_len = sizeof(ifreq);
72 ioc.ic_dp = (char *) ifreq;
73 m = ioctl(s, I_STR, (char *) &ioc);
74 ifconf.ifc_len = ioc.ic_len;
75 ifconf.ifc_req = ifreq;
77 ifconf.ifc_len = sizeof(ifreq);
78 ifconf.ifc_req = ifreq;
79 m = ioctl(s, SIOCGIFCONF, (caddr_t) & ifconf);
81 if ((m < 0) || (ifconf.ifc_len <= 0)) {
82 report(LOG_ERR, "ioctl SIOCGIFCONF");
83 return (struct ifreq *) 0;
86 maxmatch = 7; /* this many bits or less... */
87 ifrmax = (struct ifreq *) 0;/* ... is not a valid match */
91 ifrq = (struct ifreq *) p;
92 sip = (struct sockaddr_in *) &ifrq->ifr_addr;
93 m = nmatch(addrp, &(sip->sin_addr));
99 /* BSD not defined or earlier than 4.3 */
100 incr = sizeof(*ifrq);
102 incr = ifrq->ifr_addr.sa_len + IFNAMSIZ;
113 * Return the number of leading bits matching in the
114 * internet addresses supplied.
116 * ca, cb ptrs to IP address, network order
119 nmatch(u_char *ca, u_char *cb)
121 u_int m = 0; /* count of matching bits */
122 u_int n = 4; /* bytes left, then bitmask */
124 /* Count matching bytes. */
125 while (n && (*ca == *cb)) {
131 /* Now count matching bits. */
134 while (n && ((*ca & n) == (*cb & n))) {
146 * c-argdecl-indent: 4
147 * c-continued-statement-offset: 4
148 * c-continued-brace-offset: -4