1 /* vi: set sw=4 ts=4: */
2 /*
3 * Copyright (C) 2011 Denys Vlasenko.
4 *
5 * Licensed under GPLv2, see file LICENSE in this source tree.
6 */
7 #include "common.h"
8 #include "d6_common.h"
9 #include <net/if.h>
10 #include <ifaddrs.h>
11 #include <netpacket/packet.h>
12
d6_read_interface(const char * interface,int * ifindex,struct in6_addr * nip6,uint8_t * mac)13 int FAST_FUNC d6_read_interface(
14 const char *interface,
15 int *ifindex,
16 struct in6_addr *nip6,
17 uint8_t *mac)
18 {
19 int retval = 3;
20 struct ifaddrs *ifap, *ifa;
21
22 getifaddrs(&ifap);
23 for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
24 struct sockaddr_in6 *sip6;
25
26 if (!ifa->ifa_addr || (strcmp(ifa->ifa_name, interface) != 0))
27 continue;
28
29 if (ifa->ifa_addr->sa_family == AF_PACKET) {
30 struct sockaddr_ll *sll = (void*)(ifa->ifa_addr);
31 memcpy(mac, sll->sll_addr, 6);
32 log2("MAC %02x:%02x:%02x:%02x:%02x:%02x",
33 mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]
34 );
35 *ifindex = sll->sll_ifindex;
36 log2("ifindex %d", *ifindex);
37 retval &= (3 - (1<<0));
38 }
39 #if 0
40 if (ifa->ifa_addr->sa_family == AF_INET) {
41 *nip = ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
42 log1("IP %s", inet_ntoa(((struct sockaddr_in *)ifa->ifa_addr)->sin_addr));
43 }
44 #endif
45 /* RFC 3315
46 * 16. Client Source Address and Interface Selection
47 *
48 * "When a client sends a DHCP message to the
49 * All_DHCP_Relay_Agents_and_Servers address, ... ... The client
50 * MUST use a link-local address assigned to the interface for which it
51 * is requesting configuration information as the source address in the
52 * header of the IP datagram."
53 */
54 sip6 = (void*)(ifa->ifa_addr);
55
56 if (ifa->ifa_addr->sa_family == AF_INET6
57 && IN6_IS_ADDR_LINKLOCAL(&sip6->sin6_addr)
58 ) {
59 *nip6 = sip6->sin6_addr; /* struct copy */
60 log1(
61 "IPv6 %02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
62 nip6->s6_addr[0], nip6->s6_addr[1],
63 nip6->s6_addr[2], nip6->s6_addr[3],
64 nip6->s6_addr[4], nip6->s6_addr[5],
65 nip6->s6_addr[6], nip6->s6_addr[7],
66 nip6->s6_addr[8], nip6->s6_addr[9],
67 nip6->s6_addr[10], nip6->s6_addr[11],
68 nip6->s6_addr[12], nip6->s6_addr[13],
69 nip6->s6_addr[14], nip6->s6_addr[15]
70 );
71 retval &= (3 - (1<<1));
72 }
73 }
74 freeifaddrs(ifap);
75
76 if (retval & (1<<0)) {
77 /* This iface has no MAC (e.g. ppp), generate a random one */
78 struct ifreq ifr;
79 int fd;
80
81 /*memset(&ifr, 0, sizeof(ifr)); - SIOCGIFINDEX does not need to clear all */
82 strncpy_IFNAMSIZ(ifr.ifr_name, interface);
83 fd = xsocket(AF_INET6, SOCK_RAW, IPPROTO_RAW);
84 if (ioctl(fd, SIOCGIFINDEX, &ifr) == 0) {
85 *ifindex = ifr.ifr_ifindex;
86 log2("ifindex %d", *ifindex);
87 if (((uint32_t*)mac)[0] == 0) {
88 /* invent a fictitious MAC (once) */
89 ((uint32_t*)mac)[0] = rand();
90 ((uint16_t*)mac)[2] = rand();
91 mac[0] &= 0xfc; /* make sure it's not bcast */
92 }
93 retval &= (3 - (1<<0));
94 }
95 close(fd);
96 }
97
98 if (retval == 0)
99 return retval;
100
101 if (retval & (1<<0))
102 bb_error_msg("can't get %s", "MAC");
103 if (retval & (1<<1))
104 bb_error_msg("can't get %s", "link-local IPv6 address");
105 return retval;
106 }
107
d6_listen_socket(int port,const char * inf)108 int FAST_FUNC d6_listen_socket(int port, const char *inf)
109 {
110 int fd;
111 struct sockaddr_in6 addr;
112
113 log1("opening listen socket on *:%d %s", port, inf);
114 fd = xsocket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
115
116 setsockopt_reuseaddr(fd);
117 if (setsockopt_broadcast(fd) == -1)
118 bb_simple_perror_msg_and_die("SO_BROADCAST");
119
120 /* NB: bug 1032 says this doesn't work on ethernet aliases (ethN:M) */
121 if (setsockopt_bindtodevice(fd, inf))
122 xfunc_die(); /* warning is already printed */
123
124 memset(&addr, 0, sizeof(addr));
125 addr.sin6_family = AF_INET6;
126 addr.sin6_port = htons(port);
127 /* addr.sin6_addr is all-zeros */
128 xbind(fd, (struct sockaddr *)&addr, sizeof(addr));
129
130 return fd;
131 }
132