1 /*
2 * Copyright (c) 2026 Stormshield
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7 /*
8 * A dead-simple IPv6 multicast routing daemon. It registers itself with the
9 * multicast routing code and then waits for messages from the kernel. Received
10 * messages are handled by installing multicast routes.
11 */
12
13 #include <sys/types.h>
14 #include <sys/event.h>
15 #include <sys/queue.h>
16 #include <sys/socket.h>
17
18 #include <net/if.h>
19 #include <netinet/in.h>
20 #include <netinet6/ip6_mroute.h>
21 #include <arpa/inet.h>
22
23 #include <assert.h>
24 #include <err.h>
25 #include <errno.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
30
31 struct mif {
32 const char *name;
33 int mifi;
34 int pifi;
35 STAILQ_ENTRY(mif) next;
36 };
37 static STAILQ_HEAD(, mif) miflist = STAILQ_HEAD_INITIALIZER(miflist);
38
39 static void *
xmalloc(size_t size)40 xmalloc(size_t size)
41 {
42 void *ptr;
43
44 ptr = malloc(size);
45 if (ptr == NULL)
46 err(1, "malloc");
47 return (ptr);
48 }
49
50 static void
usage(void)51 usage(void)
52 {
53 fprintf(stderr,
54 "usage: %s [-i <iface>] [-m <srcaddr>/<groupaddr>/<iface>]\n",
55 getprogname());
56 exit(1);
57 }
58
59 static void
add_route(int sd,const struct in6_addr * src,const struct in6_addr * group,mifi_t mifi)60 add_route(int sd, const struct in6_addr *src, const struct in6_addr *group,
61 mifi_t mifi)
62 {
63 struct mf6cctl mfcc;
64 struct mif *mif;
65 int error;
66
67 memset(&mfcc, 0, sizeof(mfcc));
68 mfcc.mf6cc_parent = mifi;
69 mfcc.mf6cc_origin.sin6_family = AF_INET6;
70 mfcc.mf6cc_origin.sin6_len = sizeof(struct sockaddr_in6);
71 mfcc.mf6cc_origin.sin6_addr = *src;
72 mfcc.mf6cc_mcastgrp.sin6_family = AF_INET6;
73 mfcc.mf6cc_mcastgrp.sin6_len = sizeof(struct sockaddr_in6);
74 mfcc.mf6cc_mcastgrp.sin6_addr = *group;
75
76 STAILQ_FOREACH(mif, &miflist, next) {
77 if (mif->mifi != mifi)
78 IF_SET(mif->mifi, &mfcc.mf6cc_ifset);
79 }
80
81 error = setsockopt(sd, IPPROTO_IPV6, MRT6_ADD_MFC,
82 &mfcc, sizeof(mfcc));
83 if (error != 0)
84 err(1, "setsockopt(MRT6_ADD_MFC)");
85 }
86
87 static void
handle_upcalls(int sd)88 handle_upcalls(int sd)
89 {
90 struct kevent ev;
91 int kq;
92
93 kq = kqueue();
94 if (kq < 0)
95 err(1, "kqueue");
96 EV_SET(&ev, sd, EVFILT_READ, EV_ADD | EV_ENABLE, 0, 0, NULL);
97 if (kevent(kq, &ev, 1, NULL, 0, NULL) < 0)
98 err(1, "kevent");
99
100 for (;;) {
101 char buf1[INET6_ADDRSTRLEN], buf2[INET6_ADDRSTRLEN];
102 struct mrt6msg msg;
103 ssize_t len;
104 int n;
105
106 n = kevent(kq, NULL, 0, &ev, 1, NULL);
107 if (n < 0) {
108 if (errno == EINTR)
109 break;
110 err(1, "kevent");
111 }
112 if (n == 0)
113 continue;
114 assert(n == 1);
115 assert(ev.filter == EVFILT_READ);
116
117 len = recv(sd, &msg, sizeof(msg), 0);
118 if (len < 0)
119 err(1, "recv");
120 if ((size_t)len < sizeof(msg)) {
121 warnx("short read on upcall, %zd bytes", len);
122 continue;
123 }
124
125 printf("upcall received:\n");
126 printf("msgtype=%d mif=%d src=%s dst=%s\n",
127 msg.im6_msgtype, msg.im6_mif,
128 inet_ntop(AF_INET6, &msg.im6_src, buf1, sizeof(buf1)),
129 inet_ntop(AF_INET6, &msg.im6_dst, buf2, sizeof(buf2)));
130
131 add_route(sd, &msg.im6_src, &msg.im6_dst, msg.im6_mif);
132 }
133
134 close(kq);
135 }
136
137 int
main(int argc,char ** argv)138 main(int argc, char **argv)
139 {
140 struct mif *mif;
141 int ch, error, mifi, sd, v;
142
143 mifi = 0;
144 while ((ch = getopt(argc, argv, "i:m:")) != -1) {
145 switch (ch) {
146 case 'i':
147 mif = xmalloc(sizeof(*mif));
148 mif->name = strdup(optarg);
149 mif->mifi = mifi++;
150 mif->pifi = if_nametoindex(optarg);
151 if (mif->pifi == 0)
152 errx(1, "unknown interface %s", optarg);
153 STAILQ_INSERT_TAIL(&miflist, mif, next);
154 break;
155 default:
156 usage();
157 /* NOTREACHED */
158 }
159 }
160 argc -= optind;
161 argv += optind;
162
163 sd = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
164 if (sd < 0)
165 err(1, "socket");
166
167 v = 1;
168 error = setsockopt(sd, IPPROTO_IPV6, MRT6_INIT, &v, sizeof(v));
169 if (error != 0)
170 err(1, "setsockopt(MRT6_INIT)");
171
172 STAILQ_FOREACH(mif, &miflist, next) {
173 struct mif6ctl mifc;
174
175 mifc.mif6c_mifi = mif->mifi;
176 mifc.mif6c_pifi = mif->pifi;
177 mifc.mif6c_flags = 0;
178 error = setsockopt(sd, IPPROTO_IPV6, MRT6_ADD_MIF,
179 &mifc, sizeof(mifc));
180 if (error != 0)
181 err(1, "setsockopt(MRT6_ADD_MIF) on %s", mif->name);
182 }
183
184 handle_upcalls(sd);
185
186 error = setsockopt(sd, IPPROTO_IPV6, MRT6_DONE, NULL, 0);
187 if (error != 0)
188 err(1, "setsockopt(MRT6_DONE)");
189
190 return (0);
191 }
192