int main(int argc, char **argv)
{
int ret = EX_OK;
int i;
struct group *grgid;
struct passwd *pwuid;
timer_t timerid_mld, timerid_pim;
struct pollfd fds[4];
nfds_t nfds = 0;
struct sockaddr_storage from, to;
socklen_t addrlen = sizeof(struct sockaddr_storage);
unsigned int from_ifindex;
char *buf;
ret = parse_args(argc, argv);
if (ret)
return -ret;
if (getuid()) {
fprintf(stderr, "need to run as root\n");
return EX_NOPERM;
}
if (!nofork) {
pid_t pid = fork();
if (pid < 0) {
perror("fork()");
return EX_OSERR;
} else if (pid > 0)
return EX_OK;
if (setsid() < 0) {
perror("setsid()");
return EX_OSERR;
}
if (chdir("/") < 0) {
perror("chdir(\"/\")");
return EX_OSERR;
}
openlog(basename(argv[0]), LOG_PID, LOG_DAEMON);
} else
openlog(basename(argv[0]), LOG_PID | LOG_PERROR, LOG_DAEMON);
setlogmask(LOG_UPTO(debug));
logger(LOG_NOTICE, 0, "started");
errno = 0;
mroute4 = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP);
if (mroute4 >= 0) {
if (pktinfo(mroute4) < 0) {
close(mroute4);
mroute4 = -1;
} else {
pim4 = pim_init(mroute4);
if (pim4 < 0) {
close(mroute4);
mroute4 = -1;
} else {
add_poll(fds, &nfds, mroute4);
add_poll(fds, &nfds, pim4);
}
}
}
if (mroute4 < 0)
logger(LOG_WARNING, errno, "no IPv4 support");
errno = 0;
mroute6 = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
if (mroute6 >= 0) {
if (pktinfo(mroute6) < 0) {
close(mroute6);
mroute6 = -1;
} else {
pim6 = pim_init(mroute6);
if (pim6 < 0) {
close(mroute6);
mroute6 = -1;
} else {
add_poll(fds, &nfds, mroute6);
add_poll(fds, &nfds, pim6);
}
}
}
if (mroute6 < 0)
logger(LOG_WARNING, errno, "no IPv6 support");
if (mroute4 < 0 && mroute6 < 0) {
logger(LOG_ERR, 0, "multicast routing unavailable");
ret = -EX_OSERR;
goto exit;
}
ret = route_init();
if (ret)
goto mroute;
errno = 0;
grgid = getgrnam(gid);
if (grgid) {
if (setgid(grgid->gr_gid))
logger(LOG_WARNING, errno, "unable to drop group privileges");
} else
logger(LOG_WARNING, errno, "unable to find group '%s' to drop privileges to", gid);
errno = 0;
pwuid = getpwnam(uid);
if (pwuid) {
if (setuid(pwuid->pw_uid))
logger(LOG_WARNING, errno, "unable to drop user privileges");
} else
logger(LOG_WARNING, errno, "unable to find user '%s' to drop privileges to", uid);
ret = signals(&sig_handler);
if (ret)
goto route;
ret = prime_timers(&timerid_mld, &timerid_pim);
if (ret)
goto signal;
buf = malloc(SOCK_BUFLEN);
if (buf == NULL) {
logger(LOG_ERR, 0, "malloc()");
ret = -EX_OSERR;
goto timer;
}
while (running) {
ret = poll(fds, nfds, -1);
if (ret == -1) {
if (errno == EINTR)
continue;
logger(LOG_ERR, errno, "poll()");
ret = -EX_OSERR;
running = 0;
continue;
}
for (i = 0; i < nfds; i++) {
/* TODO handle errors */
assert(!(fds[i].revents & (POLLERR | POLLHUP)));
/* either a non-event or there is something to read */
assert(!fds[i].revents || fds[i].revents & POLLIN);
if (!fds[i].revents)
continue;
if (fds[i].revents & POLLIN) {
ret = recvfromto(fds[i].fd, buf, SOCK_BUFLEN, 0,
(struct sockaddr *)&from,
(struct sockaddr *)&to,
&addrlen, &from_ifindex);
if (ret == -1)
continue;
if (fds[i].fd == pim4 || fds[i].fd == pim6)
pim_recv(fds[i].fd, buf, ret,
&from, &to, addrlen,
from_ifindex);
else
mld_recv(fds[i].fd, buf, ret,
&from, &to, addrlen,
from_ifindex);
}
}
}
free(buf);
timer:
timer_delete(timerid_mld);
timer_delete(timerid_pim);
signal:
signals(SIG_IGN);
route:
route_shutdown();
mroute:
if (mroute4 > 0) {
close(pim4);
pim_shutdown(mroute4);
}
if (mroute6 > 0) {
close(pim6);
pim_shutdown(mroute6);
}
exit:
logger(LOG_NOTICE, 0, "exiting");
closelog();
assert(ret <= 0);
return -ret;
}
/* NB: this will never set port# in 'to'!
* _Only_ IP/IPv6 address part of 'to' is _maybe_ modified.
* Typical usage is to preinit 'to' with "default" value
* before calling recv_from_to(). */
ssize_t
recv_from_to(int fd, void *buf, size_t len, int flags,
struct sockaddr *from, struct sockaddr *to,
socklen_t sa_size)
{
#ifndef IP_PKTINFO
return recvfrom(fd, buf, len, flags, from, &sa_size);
#else
/* man recvmsg and man cmsg is needed to make sense of code below */
struct iovec iov[1];
union {
char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
#endif
} u;
struct cmsghdr *cmsgptr;
struct msghdr msg;
socklen_t recv_length;
iov[0].iov_base = buf;
iov[0].iov_len = len;
memset(&msg, 0, sizeof(msg));
msg.msg_name = (struct sockaddr *)from;
msg.msg_namelen = sa_size;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_control = &u;
msg.msg_controllen = sizeof(u);
recv_length = recvmsg(fd, &msg, flags);
if (recv_length < 0)
return recv_length;
/* Here we try to retrieve destination IP and memorize it */
for (cmsgptr = CMSG_FIRSTHDR(&msg);
cmsgptr != NULL;
cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)
) {
if (cmsgptr->cmsg_level == IPPROTO_IP
&& cmsgptr->cmsg_type == IP_PKTINFO
) {
#define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )
to->sa_family = AF_INET;
((struct sockaddr_in*)to)->sin_addr = pktinfo(cmsgptr)->ipi_addr;
/* ((struct sockaddr_in*)to)->sin_port = 123; */
#undef pktinfo
break;
}
#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
if (cmsgptr->cmsg_level == IPPROTO_IPV6
&& cmsgptr->cmsg_type == IPV6_PKTINFO
) {
#define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )
to->sa_family = AF_INET6;
((struct sockaddr_in6*)to)->sin6_addr = pktinfo(cmsgptr)->ipi6_addr;
/* ((struct sockaddr_in6*)to)->sin6_port = 123; */
#undef pktinfo
break;
}
#endif
}
return recv_length;
#endif
}