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. */
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");
86 maxmatch
= 7; /* this many bits or less... */
87 ifrmax
= NULL
; /* ... 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