2 * getif.c : get an interface structure
8 #include <sys/socket.h>
11 #if defined(SUNOS) || defined(SVR4)
12 #include <sys/sockio.h>
15 #include <sys/stropts.h>
18 #include <sys/time.h> /* for struct timeval in net/if.h */
19 #include <net/if.h> /* for struct ifreq */
20 #include <netinet/in.h>
36 static struct ifreq ifreq[10]; /* Holds interface configuration */
37 static struct ifconf ifconf; /* points to ifreq */
39 static int nmatch(u_char *ca, u_char *cb);
41 /* Return a pointer to the interface struct for the passed address. */
44 int s; /* socket file descriptor */
45 struct in_addr *addrp; /* destination address on interface */
49 struct ifreq *ifrq, *ifrmax;
50 struct sockaddr_in *sip;
53 /* If no address was supplied, just return NULL. */
55 return (struct ifreq *) 0;
57 /* Get the interface config if not done already. */
58 if (ifconf.ifc_len == 0) {
61 * SysVr4 returns garbage if you do this the obvious way!
62 * This one took a while to figure out... -gwr
65 ioc.ic_cmd = SIOCGIFCONF;
67 ioc.ic_len = sizeof(ifreq);
68 ioc.ic_dp = (char *) ifreq;
69 m = ioctl(s, I_STR, (char *) &ioc);
70 ifconf.ifc_len = ioc.ic_len;
71 ifconf.ifc_req = ifreq;
73 ifconf.ifc_len = sizeof(ifreq);
74 ifconf.ifc_req = ifreq;
75 m = ioctl(s, SIOCGIFCONF, (caddr_t) & ifconf);
77 if ((m < 0) || (ifconf.ifc_len <= 0)) {
78 report(LOG_ERR, "ioctl SIOCGIFCONF");
79 return (struct ifreq *) 0;
82 maxmatch = 7; /* this many bits or less... */
83 ifrmax = (struct ifreq *) 0;/* ... is not a valid match */
87 ifrq = (struct ifreq *) p;
88 sip = (struct sockaddr_in *) &ifrq->ifr_addr;
89 m = nmatch((u_char *)addrp, (u_char *)&(sip->sin_addr));
95 /* BSD not defined or earlier than 4.3 */
98 incr = ifrq->ifr_addr.sa_len + IFNAMSIZ;
109 * Return the number of leading bits matching in the
110 * internet addresses supplied.
114 u_char *ca, *cb; /* ptrs to IP address, network order */
116 u_int m = 0; /* count of matching bits */
117 u_int n = 4; /* bytes left, then bitmask */
119 /* Count matching bytes. */
120 while (n && (*ca == *cb)) {
126 /* Now count matching bits. */
129 while (n && ((*ca & n) == (*cb & n))) {
141 * c-argdecl-indent: 4
142 * c-continued-statement-offset: 4
143 * c-continued-brace-offset: -4