1 /*
2 * linklocal - print ipv6 link-local or 6to4 address of a mac address.
3 * eui is ieee's extended unique identifier, per rfc2373.
4 */
5
6 #include <u.h>
7 #include <libc.h>
8 #include <ip.h>
9
10 enum {
11 Mac0mcast = 1<<0, /* multicast address */
12 Mac0localadm = 1<<1, /* locally-administered address, */
13 V60globaladm = 1<<1, /* but ipv6 reverses the meaning */
14 };
15
16 static char *v4_6to4;
17
18 static void
usage(void)19 usage(void)
20 {
21 fprint(2, "usage: %s [-t ipv4] ether...\n", argv0);
22 exits("usage");
23 }
24
25 void
ea2eui64(uchar * lla,uchar * ea)26 ea2eui64(uchar *lla, uchar *ea)
27 {
28 *lla++ = *ea++ | V60globaladm; /* oui (company id) */
29 *lla++ = *ea++; /* " */
30 *lla++ = *ea++; /* " */
31 *lla++ = 0xFF; /* mac-48 in eui-64 (sic) */
32 *lla++ = 0xFE; /* " */
33 *lla++ = *ea++; /* manufacturer-assigned */
34 *lla++ = *ea++; /* " */
35 *lla = *ea; /* " */
36 }
37
38 void
eaip26to4(uchar * lla,uchar * ea,uchar * ipv4)39 eaip26to4(uchar *lla, uchar *ea, uchar *ipv4)
40 {
41 *lla++ = 0x20; /* 6to4 address */
42 *lla++ = 0x02; /* " */
43 memmove(lla, ipv4, IPv4addrlen);
44 lla += IPv4addrlen;
45 memset(lla, 0, 2);
46 ea2eui64(lla + 2, ea);
47 }
48
49 void
ea2lla(uchar * lla,uchar * ea)50 ea2lla(uchar *lla, uchar *ea)
51 {
52 *lla++ = 0xFE; /* link-local v6 */
53 *lla++ = 0x80; /* " */
54 memset(lla, 0, 6);
55 ea2eui64(lla + 6, ea);
56 }
57
58 static void
process(char * ether)59 process(char *ether)
60 {
61 uchar ethaddr[6], ipaddr[IPaddrlen], ipv4[IPv4addrlen];
62
63 if (parseether(ethaddr, ether) < 0)
64 sysfatal("%s: not an ether address", ether);
65 if (v4_6to4) {
66 v4parseip(ipv4, v4_6to4);
67 eaip26to4(ipaddr, ethaddr, ipv4);
68 } else
69 ea2lla(ipaddr, ethaddr);
70 print("%I\n", ipaddr);
71 }
72
73 void
main(int argc,char * argv[])74 main(int argc, char *argv[])
75 {
76 int i;
77
78 ARGBEGIN {
79 case 't':
80 v4_6to4 = EARGF(usage());
81 break;
82 default:
83 usage();
84 break;
85 } ARGEND
86
87 fmtinstall('I', eipfmt);
88 if (argc <= 0)
89 usage();
90
91 for (i = 0; i < argc; i++)
92 process(argv[i]);
93 exits(0);
94 }
95