int main (int argc, char **argv)
{
char *int_err_string;
int cachesize = CACHESIZ;
int port = NAMESERVER_PORT;
int query_port = 0;
unsigned long local_ttl = 0;
int logged_lease = 0, first_loop = 1;
unsigned int options;
char *runfile = RUNFILE;
time_t resolv_changed = 0;
time_t now, last = 0;
time_t lease_file_change = 0;
ino_t lease_file_inode = (ino_t)0;
struct irec *iface, *interfaces = NULL;
char *mxname = NULL;
char *mxtarget = NULL;
char *lease_file = NULL;
char *addn_hosts = NULL;
char *domain_suffix = NULL;
char *username = CHUSER;
char *groupname = CHGRP;
struct iname *if_names = NULL;
struct iname *if_addrs = NULL;
struct iname *if_except = NULL;
struct iname *if_tmp;
struct server *serv_addrs = NULL;
char *dnamebuff, *packet;
struct server *servers, *last_server;
struct resolvc default_resolv = { NULL, 1, 0, RESOLVFILE };
struct resolvc *resolv = &default_resolv;
struct bogus_addr *bogus_addr = NULL;
struct serverfd *serverfdp, *sfds = NULL;
sighup = 1; /* init cache the first time through */
sigusr1 = 0; /* but don't dump */
sigusr2 = 0; /* or rescan interfaces */
signal(SIGUSR1, sig_handler);
signal(SIGUSR2, sig_handler);
signal(SIGHUP, sig_handler);
/* These get allocated here to avoid overflowing the small stack
on embedded systems. dnamebuff is big enough to hold one
maximal sixed domain name and gets passed into all the processing
code. We manage to get away with one buffer. */
dnamebuff = safe_malloc(MAXDNAME);
/* Size: we check after adding each record, so there must be
memory for the largest packet, and the largest record */
packet = safe_malloc(PACKETSZ+MAXDNAME+RRFIXEDSZ);
options = read_opts(argc, argv, dnamebuff, &resolv, &mxname, &mxtarget, &lease_file,
&username, &groupname, &domain_suffix, &runfile,
&if_names, &if_addrs, &if_except, &bogus_addr,
&serv_addrs, &cachesize, &port, &query_port, &local_ttl, &addn_hosts);
int_err_string = enumerate_interfaces(&interfaces, if_names, if_addrs, if_except, port);
if (int_err_string)
die(int_err_string, NULL);
for (if_tmp = if_names; if_tmp; if_tmp = if_tmp->next)
if (if_tmp->name && !if_tmp->found)
die("unknown interface %s", if_tmp->name);
for (if_tmp = if_addrs; if_tmp; if_tmp = if_tmp->next)
if (!if_tmp->found)
{
char addrbuff[ADDRSTRLEN];
#ifdef HAVE_IPV6
if (if_tmp->addr.sa.sa_family == AF_INET)
inet_ntop(AF_INET, &if_tmp->addr.in.sin_addr,
addrbuff, ADDRSTRLEN);
else
inet_ntop(AF_INET6, &if_tmp->addr.in6.sin6_addr,
addrbuff, ADDRSTRLEN);
#else
strcpy(addrbuff, inet_ntoa(if_tmp->addr.in.sin_addr));
#endif
die("no interface with address %s", addrbuff);
}
forward_init(1);
cache_init(cachesize, options & OPT_LOG);
setbuf(stdout, NULL);
if (!(options & OPT_DEBUG))
{
FILE *pidfile;
struct passwd *ent_pw;
int i;
/* The following code "daemonizes" the process.
See Stevens section 12.4 */
#ifndef NO_FORK
if (fork() != 0 )
exit(0);
setsid();
if (fork() != 0)
exit(0);
#endif
chdir("/");
umask(022); /* make pidfile 0644 */
/* write pidfile _after_ forking ! */
if (runfile && (pidfile = fopen(runfile, "w")))
{
fprintf(pidfile, "%d\n", (int) getpid());
fclose(pidfile);
}
umask(0);
for (i=0; i<64; i++)
{
for (iface = interfaces; iface; iface = iface->next)
if (iface->fd == i)
break;
if (iface)
continue;
close(i);
}
/* Change uid and gid for security */
if (username && (ent_pw = getpwnam(username)))
{
gid_t dummy;
struct group *gp;
/* remove all supplimentary groups */
setgroups(0, &dummy);
/* change group for /etc/ppp/resolv.conf
otherwise get the group for "nobody" */
if ((groupname && (gp = getgrnam(groupname))) ||
(gp = getgrgid(ent_pw->pw_gid)))
setgid(gp->gr_gid);
/* finally drop root */
setuid(ent_pw->pw_uid);
}
}
openlog("dnsmasq",
DNSMASQ_LOG_OPT(options & OPT_DEBUG),
DNSMASQ_LOG_FAC(options & OPT_DEBUG));
if (cachesize)
syslog(LOG_INFO, "started, version %s cachesize %d", VERSION, cachesize);
else
syslog(LOG_INFO, "started, version %s cache disabled", VERSION);
if (options & OPT_LOCALMX)
syslog(LOG_INFO, "serving MX record for local hosts target %s", mxtarget);
else if (mxname)
syslog(LOG_INFO, "serving MX record for mailhost %s target %s",
mxname, mxtarget);
if (getuid() == 0 || geteuid() == 0)
syslog(LOG_WARNING, "failed to drop root privs");
servers = last_server = check_servers(serv_addrs, interfaces, &sfds);
while (1)
{
int ready, maxfd = 0;
fd_set rset;
HEADER *header;
struct stat statbuf;
if (first_loop)
/* do init stuff only first time round. */
{
first_loop = 0;
ready = 0;
}
else
{
FD_ZERO(&rset);
for (serverfdp = sfds; serverfdp; serverfdp = serverfdp->next)
{
FD_SET(serverfdp->fd, &rset);
if (serverfdp->fd > maxfd)
maxfd = serverfdp->fd;
}
for (iface = interfaces; iface; iface = iface->next)
{
FD_SET(iface->fd, &rset);
if (iface->fd > maxfd)
maxfd = iface->fd;
}
ready = select(maxfd+1, &rset, NULL, NULL, NULL);
if (ready == -1)
{
if (errno == EINTR)
ready = 0; /* do signal handlers */
else
continue;
}
}
if (sighup)
{
signal(SIGHUP, SIG_IGN);
cache_reload(options, dnamebuff, domain_suffix, addn_hosts);
if (resolv && (options & OPT_NO_POLL))
servers = last_server =
check_servers(reload_servers(resolv->name, dnamebuff, servers, query_port),
interfaces, &sfds);
sighup = 0;
signal(SIGHUP, sig_handler);
}
if (sigusr1)
{
signal(SIGUSR1, SIG_IGN);
dump_cache(options & (OPT_DEBUG | OPT_LOG), cachesize);
sigusr1 = 0;
signal(SIGUSR1, sig_handler);
}
if (sigusr2)
{
signal(SIGUSR2, SIG_IGN);
if (getuid() != 0 && port <= 1024)
syslog(LOG_ERR, "cannot re-scan interfaces unless --user=root");
else
{
syslog(LOG_INFO, "rescanning network interfaces");
int_err_string = enumerate_interfaces(&interfaces, if_names, if_addrs, if_except, port);
if (int_err_string)
syslog(LOG_ERR, int_err_string, strerror(errno));
}
sigusr2 = 0;
signal(SIGUSR2, sig_handler);
/* may be new file descriptors now, so redo select() */
ready = 0;
}
now = time(NULL);
/* Check for changes to resolv files and DHCP leases file once per second max. */
if (last == 0 || now > last)
{
last = now;
if (!(options & OPT_NO_POLL))
{
struct resolvc *res = resolv, *latest = NULL;
time_t last_change = 0;
/* There may be more than one possible file.
Go through and find the one which changed _last_.
Warn of any which can't be read. */
while (res)
{
if (stat(res->name, &statbuf) == -1)
{
if (!res->logged)
syslog(LOG_WARNING, "failed to access %s: %m", res->name);
res->logged = 1;
}
else
{
res->logged = 0;
if (statbuf.st_mtime > last_change)
{
last_change = statbuf.st_mtime;
latest = res;
}
}
res = res->next;
}
if (latest && last_change > resolv_changed)
{
resolv_changed = last_change;
servers = last_server =
check_servers(reload_servers(latest->name, dnamebuff, servers, query_port),
interfaces, &sfds);
}
}
if (lease_file)
{
syslog(LOG_WARNING, "checking lease file %s", lease_file);
if (stat(lease_file, &statbuf) == -1)
{
if (!logged_lease)
syslog(LOG_WARNING, "failed to access %s: %m", lease_file);
logged_lease = 1;
}
else
{
logged_lease = 0;
if ((statbuf.st_mtime != lease_file_change) ||
(statbuf.st_ino != lease_file_inode))
{
lease_file_change = statbuf.st_mtime;
lease_file_inode = statbuf.st_ino;
load_dhcp(lease_file, domain_suffix, now, dnamebuff);
}
}
}
}
if (ready == 0)
continue; /* no sockets ready */
for (serverfdp = sfds; serverfdp; serverfdp = serverfdp->next)
if (FD_ISSET(serverfdp->fd, &rset))
last_server = reply_query(serverfdp->fd, options, packet, now,
dnamebuff, last_server, bogus_addr);
for (iface = interfaces; iface; iface = iface->next)
{
if (FD_ISSET(iface->fd, &rset))
{
/* request packet, deal with query */
union mysockaddr udpaddr;
socklen_t udplen = sizeof(udpaddr);
int m, n = recvfrom(iface->fd, packet, PACKETSZ, 0, &udpaddr.sa, &udplen);
udpaddr.sa.sa_family = iface->addr.sa.sa_family;
#ifdef HAVE_IPV6
if (udpaddr.sa.sa_family == AF_INET6)
udpaddr.in6.sin6_flowinfo = htonl(0);
#endif
header = (HEADER *)packet;
if (n >= (int)sizeof(HEADER) && !header->qr)
{
if (extract_request(header, (unsigned int)n, dnamebuff))
{
if (udpaddr.sa.sa_family == AF_INET)
log_query(F_QUERY | F_IPV4 | F_FORWARD, dnamebuff,
(struct all_addr *)&udpaddr.in.sin_addr);
#ifdef HAVE_IPV6
else
log_query(F_QUERY | F_IPV6 | F_FORWARD, dnamebuff,
(struct all_addr *)&udpaddr.in6.sin6_addr);
#endif
}
m = answer_request (header, ((char *) header) + PACKETSZ, (unsigned int)n,
mxname, mxtarget, options, now, local_ttl, dnamebuff);
if (m >= 1)
{
/* answered from cache, send reply */
sendto(iface->fd, (char *)header, m, 0,
&udpaddr.sa, sa_len(&udpaddr));
}
else
{
/* cannot answer from cache, send on to real nameserver */
last_server = forward_query(iface->fd, &udpaddr, header, n,
options, dnamebuff, servers,
last_server, now, local_ttl);
}
}
}
}
}
return 0;
}
int main (int argc, char **argv)
{
int i;
int cachesize = CACHESIZ;
int port = NAMESERVER_PORT;
unsigned int options;
int first_loop = 1;
#ifdef HAVE_FILE_SYSTEM
int logged_resolv = 0, logged_lease = 0;
char *resolv = RESOLVFILE;
char *runfile = RUNFILE;
time_t resolv_changed = 0;
char *lease_file = NULL;
off_t lease_file_size = (off_t)0;
ino_t lease_file_inode = (ino_t)0;
#endif
struct irec *iface;
int peerfd, peerfd6;
struct irec *interfaces = NULL;
char *mxname = NULL;
char *mxtarget = NULL;
char *domain_suffix = NULL;
char *username = CHUSER;
struct iname *if_names = NULL;
struct iname *if_addrs = NULL;
struct server *serv_addrs = NULL;
char *dnamebuff, *packet;
struct server *servers, *last_server;
sighup = 1; /* init cache the first time through */
sigusr1 = 0; /* but don't dump */
signal(SIGUSR1, sig_handler);
signal(SIGHUP, sig_handler);
/* These get allocated here to avoid overflowing the small stack
on embedded systems. dnamebuff is big enough to hold one
maximal sixed domain name and gets passed into all the processing
code. We manage to get away with one buffer. */
dnamebuff = safe_malloc(MAXDNAME);
/* Size: we check after adding each record, so there must be
memory for the largest packet, and the largest record */
packet = safe_malloc(PACKETSZ+MAXDNAME+RRFIXEDSZ);
#ifdef HAVE_FILE_SYSTEM
options = read_opts(argc, argv, dnamebuff, &resolv, &mxname, &mxtarget, &lease_file,
&username, &domain_suffix, &runfile, &if_names, &if_addrs,
&serv_addrs, &cachesize, &port) ;
#else
options = read_opts(argc, argv, dnamebuff, NULL, &mxname, &mxtarget, NULL,
&username, &domain_suffix, NULL, &if_names, &if_addrs,
&serv_addrs, &cachesize, &port) ;
#endif
/* peerfd is not bound to a low port
so that we can send queries out on it without them getting
blocked at firewalls */
if ((peerfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1 &&
errno != EAFNOSUPPORT &&
errno != EINVAL)
die("dnsmasq: cannot create socket: %s", NULL);
#ifdef HAVE_IPV6
if ((peerfd6 = socket(AF_INET6, SOCK_DGRAM, 0)) == -1 &&
errno != EAFNOSUPPORT &&
errno != EINVAL)
die("dnsmasq: cannot create IPv6 socket: %s", NULL);
#else
peerfd6 = -1;
#endif
if (peerfd == -1 && peerfd6 == -1)
die("dnsmasq: no kernel support for IPv4 _or_ IPv6.", NULL);
interfaces = find_all_interfaces(if_names, if_addrs, port);
/* open a socket bound to NS port on each local interface.
this is necessary to ensure that our replies originate from
the address they were sent to. See Stevens page 531 */
for (iface = interfaces; iface; iface = iface->next)
{
if ((iface->fd = socket(iface->addr.sa.sa_family, SOCK_DGRAM, 0)) == -1)
die("cannot create socket: %s", NULL);
if (bind(iface->fd, &iface->addr.sa, sa_len(&iface->addr)))
die("bind failed: %s", NULL);
}
forward_init(1);
cache_init(cachesize, options & OPT_LOG);
setbuf(stdout, NULL);
#ifdef HAVE_FILE_SYSTEM
if (!(options & OPT_DEBUG))
{
FILE *pidfile;
struct passwd *ent_pw;
/* The following code "daemonizes" the process.
See Stevens section 12.4 */
#ifdef HAVE_FORK
if (fork() != 0 )
exit(0);
setsid();
if (fork() != 0)
exit(0);
#endif
chdir("/");
umask(022); /* make pidfile 0644 */
/* write pidfile _after_ forking ! */
if (runfile && (pidfile = fopen(runfile, "w")))
{
fprintf(pidfile, "%d\n", (int) getpid());
fclose(pidfile);
}
umask(0);
for (i=0; i<64; i++)
{
if (i == peerfd || i == peerfd6)
continue;
for (iface = interfaces; iface; iface = iface->next)
if (iface->fd == i)
break;
if (!iface)
close(i);
}
/* Change uid and gid for security */
if (username && (ent_pw = getpwnam(username)))
{
gid_t dummy;
struct group *gp;
/* remove all supplimentary groups */
setgroups(0, &dummy);
/* change group to "dip" if it exists, for /etc/ppp/resolv.conf
otherwise get the group for "nobody" */
if ((gp = getgrnam("dip")) || (gp = getgrgid(ent_pw->pw_gid)))
setgid(gp->gr_gid);
/* finally drop root */
setuid(ent_pw->pw_uid);
}
}
#else
#endif
/* In debug mode, log to stderr too and cut the prefix crap. */
openlog("dnsmasq", options & OPT_DEBUG ? LOG_PERROR : LOG_PID, LOG_DAEMON);
if (cachesize)
syslog(LOG_INFO, "started, version %s cachesize %d", VERSION, cachesize);
else
syslog(LOG_INFO, "started, version %s cache disabled", VERSION);
if (mxname)
syslog(LOG_INFO, "serving MX record for mailhost %s target %s",
mxname, mxtarget);
if (getuid() == 0 || geteuid() == 0)
syslog(LOG_WARNING, "failed to drop root privs");
serv_addrs = servers = last_server = check_servers(serv_addrs, interfaces, peerfd, peerfd6);
while (1)
{
int ready, maxfd = peerfd > peerfd6 ? peerfd : peerfd6;
fd_set rset;
HEADER *header;
#ifdef HAVE_FILE_SYSTEM
struct stat statbuf;
#endif
if (first_loop)
/* do init stuff only first time round. */
{
first_loop = 0;
ready = 0;
}
else
{
FD_ZERO(&rset);
if (peerfd != -1)
FD_SET(peerfd, &rset);
if (peerfd6 != -1)
FD_SET(peerfd6, &rset);
for (iface = interfaces; iface; iface = iface->next)
{
FD_SET(iface->fd, &rset);
if (iface->fd > maxfd)
maxfd = iface->fd;
}
ready = select(maxfd+1, &rset, NULL, NULL, NULL);
if (ready == -1)
{
if (errno == EINTR)
ready = 0; /* do signal handlers */
else
continue;
}
}
#ifdef HAVE_FILE_SYSTEM
if (sighup)
{
signal(SIGHUP, SIG_IGN);
cache_reload(options & OPT_NO_HOSTS, dnamebuff);
if (resolv && (options & OPT_NO_POLL))
servers = last_server =
check_servers(reload_servers(resolv, dnamebuff, servers),
interfaces, peerfd, peerfd6);
sighup = 0;
signal(SIGHUP, sig_handler);
}
if (sigusr1)
{
signal(SIGUSR1, SIG_IGN);
dump_cache(options & (OPT_DEBUG | OPT_LOG), cachesize);
sigusr1 = 0;
signal(SIGUSR1, sig_handler);
}
if (resolv && !(options & OPT_NO_POLL))
{
if (stat(resolv, &statbuf) == -1)
{
if (!logged_resolv)
syslog(LOG_WARNING, "failed to access %s: %m", resolv);
logged_resolv = 1;
}
else
{
logged_resolv = 0;
if ((statbuf.st_mtime > resolv_changed) &&
(statbuf.st_mtime < time(NULL) || resolv_changed == 0))
{
resolv_changed = statbuf.st_mtime;
servers = last_server =
check_servers(reload_servers(resolv, dnamebuff, servers),
interfaces, peerfd, peerfd6);
}
}
}
#else
#endif
#ifdef HAVE_FILE_SYSTEM
if (lease_file)
{
if (stat(lease_file, &statbuf) == -1)
{
if (!logged_lease)
syslog(LOG_WARNING, "failed to access %s: %m", lease_file);
logged_lease = 1;
}
else
{
logged_lease = 0;
if ((lease_file_size == (off_t)0) ||
(statbuf.st_size > lease_file_size) ||
(statbuf.st_ino != lease_file_inode))
{
lease_file_size = statbuf.st_size;
lease_file_inode = statbuf.st_ino;
load_dhcp(lease_file, domain_suffix, time(NULL), dnamebuff);
}
}
}
#else
#endif
if (ready == 0)
continue; /* no sockets ready */
if (peerfd != -1 && FD_ISSET(peerfd, &rset))
last_server = reply_query(peerfd, packet, dnamebuff, last_server);
if (peerfd6 != -1 && FD_ISSET(peerfd6, &rset))
last_server = reply_query(peerfd6, packet, dnamebuff, last_server);
for (iface = interfaces; iface; iface = iface->next)
{
if (FD_ISSET(iface->fd, &rset))
{
/* request packet, deal with query */
union mysockaddr udpaddr;
socklen_t udplen = sizeof(udpaddr);
int m, n = recvfrom(iface->fd, packet, PACKETSZ, 0, &udpaddr.sa, &udplen);
udpaddr.sa.sa_family = iface->addr.sa.sa_family;
#ifdef HAVE_IPV6
if (udpaddr.sa.sa_family == AF_INET6)
udpaddr.in6.sin6_flowinfo = htonl(0);
#endif
header = (HEADER *)packet;
if (n >= (int)sizeof(HEADER) && !header->qr)
{
m = answer_request (header, ((char *) header) + PACKETSZ, (unsigned int)n,
mxname, mxtarget, options, dnamebuff);
if (m >= 1)
{
/* answered from cache, send reply */
sendto(iface->fd, (char *)header, m, 0,
&udpaddr.sa, sa_len(&udpaddr));
}
else
{
/* cannot answer from cache, send on to real nameserver */
last_server = forward_query(iface->fd, peerfd, peerfd6, &udpaddr, header, n,
options && OPT_ORDER, dnamebuff,
servers, last_server);
}
}
}
}
}
return 0;
}