| /* dnsmasq is Copyright (c) 2000-2015 Simon Kelley |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; version 2 dated June, 1991, or |
| (at your option) version 3 dated 29 June, 2007. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| /* Declare static char *compiler_opts in config.h */ |
| #define DNSMASQ_COMPILE_OPTS |
| |
| #include "dnsmasq.h" |
| |
| struct daemon *daemon; |
| |
| static volatile pid_t pid = 0; |
| static volatile int pipewrite; |
| |
| static int set_dns_listeners(time_t now); |
| static void check_dns_listeners(time_t now); |
| static void sig_handler(int sig); |
| static void async_event(int pipe, time_t now); |
| static void fatal_event(struct event_desc *ev, char *msg); |
| static int read_event(int fd, struct event_desc *evp, char **msg); |
| static void poll_resolv(int force, int do_reload, time_t now); |
| |
| int main (int argc, char **argv) |
| { |
| int bind_fallback = 0; |
| time_t now; |
| struct sigaction sigact; |
| struct iname *if_tmp; |
| int piperead, pipefd[2], err_pipe[2]; |
| struct passwd *ent_pw = NULL; |
| #if defined(HAVE_SCRIPT) |
| uid_t script_uid = 0; |
| gid_t script_gid = 0; |
| #endif |
| struct group *gp = NULL; |
| long i, max_fd = sysconf(_SC_OPEN_MAX); |
| char *baduser = NULL; |
| int log_err; |
| #if defined(HAVE_LINUX_NETWORK) |
| cap_user_header_t hdr = NULL; |
| cap_user_data_t data = NULL; |
| char *bound_device = NULL; |
| int did_bind = 0; |
| #endif |
| #if defined(HAVE_DHCP) || defined(HAVE_DHCP6) |
| struct dhcp_context *context; |
| struct dhcp_relay *relay; |
| #endif |
| #ifdef HAVE_TFTP |
| int tftp_prefix_missing = 0; |
| #endif |
| |
| #ifdef LOCALEDIR |
| setlocale(LC_ALL, ""); |
| bindtextdomain("dnsmasq", LOCALEDIR); |
| textdomain("dnsmasq"); |
| #endif |
| |
| sigact.sa_handler = sig_handler; |
| sigact.sa_flags = 0; |
| sigemptyset(&sigact.sa_mask); |
| sigaction(SIGUSR1, &sigact, NULL); |
| sigaction(SIGUSR2, &sigact, NULL); |
| sigaction(SIGHUP, &sigact, NULL); |
| sigaction(SIGTERM, &sigact, NULL); |
| sigaction(SIGALRM, &sigact, NULL); |
| sigaction(SIGCHLD, &sigact, NULL); |
| |
| /* ignore SIGPIPE */ |
| sigact.sa_handler = SIG_IGN; |
| sigaction(SIGPIPE, &sigact, NULL); |
| |
| umask(022); /* known umask, create leases and pid files as 0644 */ |
| |
| rand_init(); /* Must precede read_opts() */ |
| |
| read_opts(argc, argv, compile_opts); |
| |
| if (daemon->edns_pktsz < PACKETSZ) |
| daemon->edns_pktsz = PACKETSZ; |
| |
| /* Min buffer size: we check after adding each record, so there must be |
| memory for the largest packet, and the largest record so the |
| min for DNS is PACKETSZ+MAXDNAME+RRFIXEDSZ which is < 1000. |
| This might be increased is EDNS packet size if greater than the minimum. */ |
| daemon->packet_buff_sz = daemon->edns_pktsz + MAXDNAME + RRFIXEDSZ; |
| daemon->packet = safe_malloc(daemon->packet_buff_sz); |
| |
| daemon->addrbuff = safe_malloc(ADDRSTRLEN); |
| if (option_bool(OPT_EXTRALOG)) |
| daemon->addrbuff2 = safe_malloc(ADDRSTRLEN); |
| |
| #ifdef HAVE_DNSSEC |
| if (option_bool(OPT_DNSSEC_VALID)) |
| { |
| /* Note that both /000 and '.' are allowed within labels. These get |
| represented in presentation format using NAME_ESCAPE as an escape |
| character when in DNSSEC mode. |
| In theory, if all the characters in a name were /000 or |
| '.' or NAME_ESCAPE then all would have to be escaped, so the |
| presentation format would be twice as long as the spec. |
| |
| daemon->namebuff was previously allocated by the option-reading |
| code before we knew if we're in DNSSEC mode, so reallocate here. */ |
| free(daemon->namebuff); |
| daemon->namebuff = safe_malloc(MAXDNAME * 2); |
| daemon->keyname = safe_malloc(MAXDNAME * 2); |
| daemon->workspacename = safe_malloc(MAXDNAME * 2); |
| } |
| #endif |
| |
| #ifdef HAVE_DHCP |
| if (!daemon->lease_file) |
| { |
| if (daemon->dhcp || daemon->dhcp6) |
| daemon->lease_file = LEASEFILE; |
| } |
| #endif |
| |
| /* Close any file descriptors we inherited apart from std{in|out|err} |
| |
| Ensure that at least stdin, stdout and stderr (fd 0, 1, 2) exist, |
| otherwise file descriptors we create can end up being 0, 1, or 2 |
| and then get accidentally closed later when we make 0, 1, and 2 |
| open to /dev/null. Normally we'll be started with 0, 1 and 2 open, |
| but it's not guaranteed. By opening /dev/null three times, we |
| ensure that we're not using those fds for real stuff. */ |
| for (i = 0; i < max_fd; i++) |
| if (i != STDOUT_FILENO && i != STDERR_FILENO && i != STDIN_FILENO) |
| close(i); |
| else |
| open("/dev/null", O_RDWR); |
| |
| #ifndef HAVE_LINUX_NETWORK |
| # if !(defined(IP_RECVDSTADDR) && defined(IP_RECVIF) && defined(IP_SENDSRCADDR)) |
| if (!option_bool(OPT_NOWILD)) |
| { |
| bind_fallback = 1; |
| set_option_bool(OPT_NOWILD); |
| } |
| # endif |
| |
| /* -- bind-dynamic not supported on !Linux, fall back to --bind-interfaces */ |
| if (option_bool(OPT_CLEVERBIND)) |
| { |
| bind_fallback = 1; |
| set_option_bool(OPT_NOWILD); |
| reset_option_bool(OPT_CLEVERBIND); |
| } |
| #endif |
| |
| #ifndef HAVE_INOTIFY |
| if (daemon->dynamic_dirs) |
| die(_("dhcp-hostsdir, dhcp-optsdir and hostsdir are not supported on this platform"), NULL, EC_BADCONF); |
| #endif |
| |
| if (option_bool(OPT_DNSSEC_VALID)) |
| { |
| #ifdef HAVE_DNSSEC |
| if (!daemon->ds) |
| die(_("no trust anchors provided for DNSSEC"), NULL, EC_BADCONF); |
| |
| if (daemon->cachesize < CACHESIZ) |
| die(_("cannot reduce cache size from default when DNSSEC enabled"), NULL, EC_BADCONF); |
| #else |
| die(_("DNSSEC not available: set HAVE_DNSSEC in src/config.h"), NULL, EC_BADCONF); |
| #endif |
| } |
| |
| #ifndef HAVE_TFTP |
| if (option_bool(OPT_TFTP)) |
| die(_("TFTP server not available: set HAVE_TFTP in src/config.h"), NULL, EC_BADCONF); |
| #endif |
| |
| #ifdef HAVE_CONNTRACK |
| if (option_bool(OPT_CONNTRACK) && (daemon->query_port != 0 || daemon->osport)) |
| die (_("cannot use --conntrack AND --query-port"), NULL, EC_BADCONF); |
| #else |
| if (option_bool(OPT_CONNTRACK)) |
| die(_("conntrack support not available: set HAVE_CONNTRACK in src/config.h"), NULL, EC_BADCONF); |
| #endif |
| |
| #ifdef HAVE_SOLARIS_NETWORK |
| if (daemon->max_logs != 0) |
| die(_("asychronous logging is not available under Solaris"), NULL, EC_BADCONF); |
| #endif |
| |
| #ifdef __ANDROID__ |
| if (daemon->max_logs != 0) |
| die(_("asychronous logging is not available under Android"), NULL, EC_BADCONF); |
| #endif |
| |
| #ifndef HAVE_AUTH |
| if (daemon->authserver) |
| die(_("authoritative DNS not available: set HAVE_AUTH in src/config.h"), NULL, EC_BADCONF); |
| #endif |
| |
| #ifndef HAVE_LOOP |
| if (option_bool(OPT_LOOP_DETECT)) |
| die(_("loop detection not available: set HAVE_LOOP in src/config.h"), NULL, EC_BADCONF); |
| #endif |
| |
| now = dnsmasq_time(); |
| |
| /* Create a serial at startup if not configured. */ |
| if (daemon->authinterface && daemon->soa_sn == 0) |
| #ifdef HAVE_BROKEN_RTC |
| die(_("zone serial must be configured in --auth-soa"), NULL, EC_BADCONF); |
| #else |
| daemon->soa_sn = now; |
| #endif |
| |
| #ifdef HAVE_DHCP6 |
| if (daemon->dhcp6) |
| { |
| daemon->doing_ra = option_bool(OPT_RA); |
| |
| for (context = daemon->dhcp6; context; context = context->next) |
| { |
| if (context->flags & CONTEXT_DHCP) |
| daemon->doing_dhcp6 = 1; |
| if (context->flags & CONTEXT_RA) |
| daemon->doing_ra = 1; |
| #if !defined(HAVE_LINUX_NETWORK) && !defined(HAVE_BSD_NETWORK) |
| if (context->flags & CONTEXT_TEMPLATE) |
| die (_("dhcp-range constructor not available on this platform"), NULL, EC_BADCONF); |
| #endif |
| } |
| } |
| #endif |
| |
| #ifdef HAVE_DHCP |
| /* Note that order matters here, we must call lease_init before |
| creating any file descriptors which shouldn't be leaked |
| to the lease-script init process. We need to call common_init |
| before lease_init to allocate buffers it uses. |
| The script subsystrm relies on DHCP buffers, hence the last two |
| conditions below. */ |
| if (daemon->dhcp || daemon->doing_dhcp6 || daemon->relay4 || |
| daemon->relay6 || option_bool(OPT_TFTP) || option_bool(OPT_ADD_MAC)) |
| { |
| dhcp_common_init(); |
| if (daemon->dhcp || daemon->doing_dhcp6) |
| lease_init(now); |
| } |
| |
| if (daemon->dhcp || daemon->relay4) |
| dhcp_init(); |
| |
| # ifdef HAVE_DHCP6 |
| if (daemon->doing_ra || daemon->doing_dhcp6 || daemon->relay6) |
| ra_init(now); |
| |
| if (daemon->doing_dhcp6 || daemon->relay6) |
| dhcp6_init(); |
| # endif |
| |
| #endif |
| |
| #ifdef HAVE_IPSET |
| if (daemon->ipsets) |
| ipset_init(); |
| #endif |
| |
| #if defined(HAVE_LINUX_NETWORK) |
| netlink_init(); |
| #elif defined(HAVE_BSD_NETWORK) |
| route_init(); |
| #endif |
| |
| if (option_bool(OPT_NOWILD) && option_bool(OPT_CLEVERBIND)) |
| die(_("cannot set --bind-interfaces and --bind-dynamic"), NULL, EC_BADCONF); |
| |
| if (!enumerate_interfaces(1) || !enumerate_interfaces(0)) |
| die(_("failed to find list of interfaces: %s"), NULL, EC_MISC); |
| |
| if (option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND)) |
| { |
| create_bound_listeners(1); |
| |
| if (!option_bool(OPT_CLEVERBIND)) |
| for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next) |
| if (if_tmp->name && !if_tmp->used) |
| die(_("unknown interface %s"), if_tmp->name, EC_BADNET); |
| |
| #if defined(HAVE_LINUX_NETWORK) && defined(HAVE_DHCP) |
| /* after enumerate_interfaces() */ |
| bound_device = whichdevice(); |
| |
| if (daemon->dhcp) |
| { |
| if (!daemon->relay4 && bound_device) |
| { |
| bindtodevice(bound_device, daemon->dhcpfd); |
| did_bind = 1; |
| } |
| if (daemon->enable_pxe && bound_device) |
| { |
| bindtodevice(bound_device, daemon->pxefd); |
| did_bind = 1; |
| } |
| } |
| #endif |
| |
| #if defined(HAVE_LINUX_NETWORK) && defined(HAVE_DHCP6) |
| if (daemon->doing_dhcp6 && !daemon->relay6 && bound_device) |
| { |
| bindtodevice(bound_device, daemon->dhcp6fd); |
| did_bind = 1; |
| } |
| #endif |
| } |
| else |
| create_wildcard_listeners(); |
| |
| #ifdef HAVE_DHCP6 |
| /* after enumerate_interfaces() */ |
| if (daemon->doing_dhcp6 || daemon->relay6 || daemon->doing_ra) |
| join_multicast(1); |
| |
| /* After netlink_init() and before create_helper() */ |
| lease_make_duid(now); |
| #endif |
| |
| if (daemon->port != 0) |
| { |
| cache_init(); |
| |
| #ifdef HAVE_DNSSEC |
| blockdata_init(); |
| #endif |
| } |
| |
| #ifdef HAVE_INOTIFY |
| if (daemon->port != 0 || daemon->dhcp || daemon->doing_dhcp6) |
| inotify_dnsmasq_init(); |
| else |
| daemon->inotifyfd = -1; |
| #endif |
| |
| if (option_bool(OPT_DBUS)) |
| #ifdef HAVE_DBUS |
| { |
| char *err; |
| daemon->dbus = NULL; |
| daemon->watches = NULL; |
| if ((err = dbus_init())) |
| die(_("DBus error: %s"), err, EC_MISC); |
| } |
| #else |
| die(_("DBus not available: set HAVE_DBUS in src/config.h"), NULL, EC_BADCONF); |
| #endif |
| |
| if (daemon->port != 0) |
| pre_allocate_sfds(); |
| |
| #if defined(HAVE_SCRIPT) |
| /* Note getpwnam returns static storage */ |
| if ((daemon->dhcp || daemon->dhcp6) && |
| daemon->scriptuser && |
| (daemon->lease_change_command || daemon->luascript)) |
| { |
| if ((ent_pw = getpwnam(daemon->scriptuser))) |
| { |
| script_uid = ent_pw->pw_uid; |
| script_gid = ent_pw->pw_gid; |
| } |
| else |
| baduser = daemon->scriptuser; |
| } |
| #endif |
| |
| if (daemon->username && !(ent_pw = getpwnam(daemon->username))) |
| baduser = daemon->username; |
| else if (daemon->groupname && !(gp = getgrnam(daemon->groupname))) |
| baduser = daemon->groupname; |
| |
| if (baduser) |
| die(_("unknown user or group: %s"), baduser, EC_BADCONF); |
| |
| /* implement group defaults, "dip" if available, or group associated with uid */ |
| if (!daemon->group_set && !gp) |
| { |
| if (!(gp = getgrnam(CHGRP)) && ent_pw) |
| gp = getgrgid(ent_pw->pw_gid); |
| |
| /* for error message */ |
| if (gp) |
| daemon->groupname = gp->gr_name; |
| } |
| |
| #if defined(HAVE_LINUX_NETWORK) |
| /* determine capability API version here, while we can still |
| call safe_malloc */ |
| if (ent_pw && ent_pw->pw_uid != 0) |
| { |
| int capsize = 1; /* for header version 1 */ |
| hdr = safe_malloc(sizeof(*hdr)); |
| |
| /* find version supported by kernel */ |
| memset(hdr, 0, sizeof(*hdr)); |
| capget(hdr, NULL); |
| |
| if (hdr->version != LINUX_CAPABILITY_VERSION_1) |
| { |
| /* if unknown version, use largest supported version (3) */ |
| if (hdr->version != LINUX_CAPABILITY_VERSION_2) |
| hdr->version = LINUX_CAPABILITY_VERSION_3; |
| capsize = 2; |
| } |
| |
| data = safe_malloc(sizeof(*data) * capsize); |
| memset(data, 0, sizeof(*data) * capsize); |
| } |
| #endif |
| |
| /* Use a pipe to carry signals and other events back to the event loop |
| in a race-free manner and another to carry errors to daemon-invoking process */ |
| safe_pipe(pipefd, 1); |
| |
| piperead = pipefd[0]; |
| pipewrite = pipefd[1]; |
| /* prime the pipe to load stuff first time. */ |
| send_event(pipewrite, EVENT_INIT, 0, NULL); |
| |
| err_pipe[1] = -1; |
| |
| if (!option_bool(OPT_DEBUG)) |
| { |
| /* The following code "daemonizes" the process. |
| See Stevens section 12.4 */ |
| |
| if (chdir("/") != 0) |
| die(_("cannot chdir to filesystem root: %s"), NULL, EC_MISC); |
| |
| #ifndef NO_FORK |
| if (!option_bool(OPT_NO_FORK)) |
| { |
| pid_t pid; |
| |
| /* pipe to carry errors back to original process. |
| When startup is complete we close this and the process terminates. */ |
| safe_pipe(err_pipe, 0); |
| |
| if ((pid = fork()) == -1) |
| /* fd == -1 since we've not forked, never returns. */ |
| send_event(-1, EVENT_FORK_ERR, errno, NULL); |
| |
| if (pid != 0) |
| { |
| struct event_desc ev; |
| char *msg; |
| |
| /* close our copy of write-end */ |
| while (retry_send(close(err_pipe[1]))); |
| |
| /* check for errors after the fork */ |
| if (read_event(err_pipe[0], &ev, &msg)) |
| fatal_event(&ev, msg); |
| |
| _exit(EC_GOOD); |
| } |
| |
| while (retry_send(close(err_pipe[0]))); |
| |
| /* NO calls to die() from here on. */ |
| |
| setsid(); |
| |
| if ((pid = fork()) == -1) |
| send_event(err_pipe[1], EVENT_FORK_ERR, errno, NULL); |
| |
| if (pid != 0) |
| _exit(0); |
| } |
| #endif |
| |
| /* write pidfile _after_ forking ! */ |
| if (daemon->runfile) |
| { |
| int fd, err = 0; |
| |
| sprintf(daemon->namebuff, "%d\n", (int) getpid()); |
| |
| /* Explanation: Some installations of dnsmasq (eg Debian/Ubuntu) locate the pid-file |
| in a directory which is writable by the non-privileged user that dnsmasq runs as. This |
| allows the daemon to delete the file as part of its shutdown. This is a security hole to the |
| extent that an attacker running as the unprivileged user could replace the pidfile with a |
| symlink, and have the target of that symlink overwritten as root next time dnsmasq starts. |
| |
| The folowing code first deletes any existing file, and then opens it with the O_EXCL flag, |
| ensuring that the open() fails should there be any existing file (because the unlink() failed, |
| or an attacker exploited the race between unlink() and open()). This ensures that no symlink |
| attack can succeed. |
| |
| Any compromise of the non-privileged user still theoretically allows the pid-file to be |
| replaced whilst dnsmasq is running. The worst that could allow is that the usual |
| "shutdown dnsmasq" shell command could be tricked into stopping any other process. |
| |
| Note that if dnsmasq is started as non-root (eg for testing) it silently ignores |
| failure to write the pid-file. |
| */ |
| |
| unlink(daemon->runfile); |
| |
| if ((fd = open(daemon->runfile, O_WRONLY|O_CREAT|O_TRUNC|O_EXCL, S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH)) == -1) |
| { |
| /* only complain if started as root */ |
| if (getuid() == 0) |
| err = 1; |
| } |
| else |
| { |
| if (!read_write(fd, (unsigned char *)daemon->namebuff, strlen(daemon->namebuff), 0)) |
| err = 1; |
| else |
| { |
| while (retry_send(close(fd))); |
| if (errno != 0) |
| err = 1; |
| } |
| } |
| |
| if (err) |
| { |
| send_event(err_pipe[1], EVENT_PIDFILE, errno, daemon->runfile); |
| _exit(0); |
| } |
| } |
| } |
| |
| log_err = log_start(ent_pw, err_pipe[1]); |
| |
| if (!option_bool(OPT_DEBUG)) |
| { |
| /* open stdout etc to /dev/null */ |
| int nullfd = open("/dev/null", O_RDWR); |
| dup2(nullfd, STDOUT_FILENO); |
| dup2(nullfd, STDERR_FILENO); |
| dup2(nullfd, STDIN_FILENO); |
| close(nullfd); |
| } |
| |
| /* if we are to run scripts, we need to fork a helper before dropping root. */ |
| daemon->helperfd = -1; |
| #ifdef HAVE_SCRIPT |
| if ((daemon->dhcp || daemon->dhcp6 || option_bool(OPT_TFTP) || option_bool(OPT_ADD_MAC)) && |
| (daemon->lease_change_command || daemon->luascript)) |
| daemon->helperfd = create_helper(pipewrite, err_pipe[1], script_uid, script_gid, max_fd); |
| #endif |
| |
| if (!option_bool(OPT_DEBUG) && getuid() == 0) |
| { |
| int bad_capabilities = 0; |
| gid_t dummy; |
| |
| /* remove all supplimentary groups */ |
| if (gp && |
| (setgroups(0, &dummy) == -1 || |
| setgid(gp->gr_gid) == -1)) |
| { |
| send_event(err_pipe[1], EVENT_GROUP_ERR, errno, daemon->groupname); |
| _exit(0); |
| } |
| |
| if (ent_pw && ent_pw->pw_uid != 0) |
| { |
| #if defined(HAVE_LINUX_NETWORK) |
| /* On linux, we keep CAP_NETADMIN (for ARP-injection) and |
| CAP_NET_RAW (for icmp) if we're doing dhcp. If we have yet to bind |
| ports because of DAD, or we're doing it dynamically, |
| we need CAP_NET_BIND_SERVICE too. */ |
| if (is_dad_listeners() || option_bool(OPT_CLEVERBIND)) |
| data->effective = data->permitted = data->inheritable = |
| (1 << CAP_NET_ADMIN) | (1 << CAP_NET_RAW) | |
| (1 << CAP_SETUID) | (1 << CAP_NET_BIND_SERVICE); |
| else |
| data->effective = data->permitted = data->inheritable = |
| (1 << CAP_NET_ADMIN) | (1 << CAP_NET_RAW) | (1 << CAP_SETUID); |
| |
| /* Tell kernel to not clear capabilities when dropping root */ |
| if (capset(hdr, data) == -1 || prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == -1) |
| bad_capabilities = errno; |
| |
| #elif defined(HAVE_SOLARIS_NETWORK) |
| /* http://developers.sun.com/solaris/articles/program_privileges.html */ |
| priv_set_t *priv_set; |
| |
| if (!(priv_set = priv_str_to_set("basic", ",", NULL)) || |
| priv_addset(priv_set, PRIV_NET_ICMPACCESS) == -1 || |
| priv_addset(priv_set, PRIV_SYS_NET_CONFIG) == -1) |
| bad_capabilities = errno; |
| |
| if (priv_set && bad_capabilities == 0) |
| { |
| priv_inverse(priv_set); |
| |
| if (setppriv(PRIV_OFF, PRIV_LIMIT, priv_set) == -1) |
| bad_capabilities = errno; |
| } |
| |
| if (priv_set) |
| priv_freeset(priv_set); |
| |
| #endif |
| |
| if (bad_capabilities != 0) |
| { |
| send_event(err_pipe[1], EVENT_CAP_ERR, bad_capabilities, NULL); |
| _exit(0); |
| } |
| |
| /* finally drop root */ |
| if (setuid(ent_pw->pw_uid) == -1) |
| { |
| send_event(err_pipe[1], EVENT_USER_ERR, errno, daemon->username); |
| _exit(0); |
| } |
| |
| #ifdef HAVE_LINUX_NETWORK |
| if (is_dad_listeners() || option_bool(OPT_CLEVERBIND)) |
| data->effective = data->permitted = |
| (1 << CAP_NET_ADMIN) | (1 << CAP_NET_RAW) | (1 << CAP_NET_BIND_SERVICE); |
| else |
| data->effective = data->permitted = |
| (1 << CAP_NET_ADMIN) | (1 << CAP_NET_RAW); |
| data->inheritable = 0; |
| |
| /* lose the setuid and setgid capbilities */ |
| if (capset(hdr, data) == -1) |
| { |
| send_event(err_pipe[1], EVENT_CAP_ERR, errno, NULL); |
| _exit(0); |
| } |
| #endif |
| |
| } |
| } |
| |
| #ifdef HAVE_LINUX_NETWORK |
| free(hdr); |
| free(data); |
| if (option_bool(OPT_DEBUG)) |
| prctl(PR_SET_DUMPABLE, 1, 0, 0, 0); |
| #endif |
| |
| #ifdef HAVE_TFTP |
| if (option_bool(OPT_TFTP)) |
| { |
| DIR *dir; |
| struct tftp_prefix *p; |
| |
| if (daemon->tftp_prefix) |
| { |
| if (!((dir = opendir(daemon->tftp_prefix)))) |
| { |
| tftp_prefix_missing = 1; |
| if (!option_bool(OPT_TFTP_NO_FAIL)) |
| { |
| send_event(err_pipe[1], EVENT_TFTP_ERR, errno, daemon->tftp_prefix); |
| _exit(0); |
| } |
| } |
| else |
| closedir(dir); |
| } |
| |
| for (p = daemon->if_prefix; p; p = p->next) |
| { |
| p->missing = 0; |
| if (!((dir = opendir(p->prefix)))) |
| { |
| p->missing = 1; |
| if (!option_bool(OPT_TFTP_NO_FAIL)) |
| { |
| send_event(err_pipe[1], EVENT_TFTP_ERR, errno, p->prefix); |
| _exit(0); |
| } |
| } |
| else |
| closedir(dir); |
| } |
| } |
| #endif |
| |
| if (daemon->port == 0) |
| my_syslog(LOG_INFO, _("started, version %s DNS disabled"), VERSION); |
| else if (daemon->cachesize != 0) |
| my_syslog(LOG_INFO, _("started, version %s cachesize %d"), VERSION, daemon->cachesize); |
| else |
| my_syslog(LOG_INFO, _("started, version %s cache disabled"), VERSION); |
| |
| my_syslog(LOG_INFO, _("compile time options: %s"), compile_opts); |
| |
| #ifdef HAVE_DBUS |
| if (option_bool(OPT_DBUS)) |
| { |
| if (daemon->dbus) |
| my_syslog(LOG_INFO, _("DBus support enabled: connected to system bus")); |
| else |
| my_syslog(LOG_INFO, _("DBus support enabled: bus connection pending")); |
| } |
| #endif |
| |
| if (option_bool(OPT_LOCAL_SERVICE)) |
| my_syslog(LOG_INFO, _("DNS service limited to local subnets")); |
| |
| #ifdef HAVE_DNSSEC |
| if (option_bool(OPT_DNSSEC_VALID)) |
| { |
| int rc; |
| |
| /* Delay creating the timestamp file until here, after we've changed user, so that |
| it has the correct owner to allow updating the mtime later. |
| This means we have to report fatal errors via the pipe. */ |
| if ((rc = setup_timestamp()) == -1) |
| { |
| send_event(err_pipe[1], EVENT_TIME_ERR, errno, daemon->timestamp_file); |
| _exit(0); |
| } |
| |
| my_syslog(LOG_INFO, _("DNSSEC validation enabled")); |
| |
| if (option_bool(OPT_DNSSEC_TIME)) |
| my_syslog(LOG_INFO, _("DNSSEC signature timestamps not checked until first cache reload")); |
| |
| if (rc == 1) |
| my_syslog(LOG_INFO, _("DNSSEC signature timestamps not checked until system time valid")); |
| } |
| #endif |
| |
| if (log_err != 0) |
| my_syslog(LOG_WARNING, _("warning: failed to change owner of %s: %s"), |
| daemon->log_file, strerror(log_err)); |
| |
| if (bind_fallback) |
| my_syslog(LOG_WARNING, _("setting --bind-interfaces option because of OS limitations")); |
| |
| if (option_bool(OPT_NOWILD)) |
| warn_bound_listeners(); |
| |
| warn_int_names(); |
| |
| if (!option_bool(OPT_NOWILD)) |
| for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next) |
| if (if_tmp->name && !if_tmp->used) |
| my_syslog(LOG_WARNING, _("warning: interface %s does not currently exist"), if_tmp->name); |
| |
| if (daemon->port != 0 && option_bool(OPT_NO_RESOLV)) |
| { |
| if (daemon->resolv_files && !daemon->resolv_files->is_default) |
| my_syslog(LOG_WARNING, _("warning: ignoring resolv-file flag because no-resolv is set")); |
| daemon->resolv_files = NULL; |
| if (!daemon->servers) |
| my_syslog(LOG_WARNING, _("warning: no upstream servers configured")); |
| } |
| |
| if (daemon->max_logs != 0) |
| my_syslog(LOG_INFO, _("asynchronous logging enabled, queue limit is %d messages"), daemon->max_logs); |
| |
| |
| #ifdef HAVE_DHCP |
| for (context = daemon->dhcp; context; context = context->next) |
| log_context(AF_INET, context); |
| |
| for (relay = daemon->relay4; relay; relay = relay->next) |
| log_relay(AF_INET, relay); |
| |
| # ifdef HAVE_DHCP6 |
| for (context = daemon->dhcp6; context; context = context->next) |
| log_context(AF_INET6, context); |
| |
| for (relay = daemon->relay6; relay; relay = relay->next) |
| log_relay(AF_INET6, relay); |
| |
| if (daemon->doing_dhcp6 || daemon->doing_ra) |
| dhcp_construct_contexts(now); |
| |
| if (option_bool(OPT_RA)) |
| my_syslog(MS_DHCP | LOG_INFO, _("IPv6 router advertisement enabled")); |
| # endif |
| |
| # ifdef HAVE_LINUX_NETWORK |
| if (did_bind) |
| my_syslog(MS_DHCP | LOG_INFO, _("DHCP, sockets bound exclusively to interface %s"), bound_device); |
| # endif |
| |
| /* after dhcp_contruct_contexts */ |
| if (daemon->dhcp || daemon->doing_dhcp6) |
| lease_find_interfaces(now); |
| #endif |
| |
| #ifdef HAVE_TFTP |
| if (option_bool(OPT_TFTP)) |
| { |
| struct tftp_prefix *p; |
| |
| my_syslog(MS_TFTP | LOG_INFO, "TFTP %s%s %s", |
| daemon->tftp_prefix ? _("root is ") : _("enabled"), |
| daemon->tftp_prefix ? daemon->tftp_prefix: "", |
| option_bool(OPT_TFTP_SECURE) ? _("secure mode") : ""); |
| |
| if (tftp_prefix_missing) |
| my_syslog(MS_TFTP | LOG_WARNING, _("warning: %s inaccessible"), daemon->tftp_prefix); |
| |
| for (p = daemon->if_prefix; p; p = p->next) |
| if (p->missing) |
| my_syslog(MS_TFTP | LOG_WARNING, _("warning: TFTP directory %s inaccessible"), p->prefix); |
| |
| /* This is a guess, it assumes that for small limits, |
| disjoint files might be served, but for large limits, |
| a single file will be sent to may clients (the file only needs |
| one fd). */ |
| |
| max_fd -= 30; /* use other than TFTP */ |
| |
| if (max_fd < 0) |
| max_fd = 5; |
| else if (max_fd < 100) |
| max_fd = max_fd/2; |
| else |
| max_fd = max_fd - 20; |
| |
| /* if we have to use a limited range of ports, |
| that will limit the number of transfers */ |
| if (daemon->start_tftp_port != 0 && |
| daemon->end_tftp_port - daemon->start_tftp_port + 1 < max_fd) |
| max_fd = daemon->end_tftp_port - daemon->start_tftp_port + 1; |
| |
| if (daemon->tftp_max > max_fd) |
| { |
| daemon->tftp_max = max_fd; |
| my_syslog(MS_TFTP | LOG_WARNING, |
| _("restricting maximum simultaneous TFTP transfers to %d"), |
| daemon->tftp_max); |
| } |
| } |
| #endif |
| |
| /* finished start-up - release original process */ |
| if (err_pipe[1] != -1) |
| while (retry_send(close(err_pipe[1]))); |
| |
| if (daemon->port != 0) |
| check_servers(); |
| |
| pid = getpid(); |
| |
| #ifdef HAVE_INOTIFY |
| /* Using inotify, have to select a resolv file at startup */ |
| poll_resolv(1, 0, now); |
| #endif |
| |
| while (1) |
| { |
| int t, timeout = -1; |
| |
| poll_reset(); |
| |
| /* if we are out of resources, find how long we have to wait |
| for some to come free, we'll loop around then and restart |
| listening for queries */ |
| if ((t = set_dns_listeners(now)) != 0) |
| timeout = t * 1000; |
| |
| /* Whilst polling for the dbus, or doing a tftp transfer, wake every quarter second */ |
| if (daemon->tftp_trans || |
| (option_bool(OPT_DBUS) && !daemon->dbus)) |
| timeout = 250; |
| |
| /* Wake every second whilst waiting for DAD to complete */ |
| else if (is_dad_listeners()) |
| timeout = 1000; |
| |
| #ifdef HAVE_DBUS |
| set_dbus_listeners(); |
| #endif |
| |
| #ifdef HAVE_DHCP |
| if (daemon->dhcp || daemon->relay4) |
| { |
| poll_listen(daemon->dhcpfd, POLLIN); |
| if (daemon->pxefd != -1) |
| poll_listen(daemon->pxefd, POLLIN); |
| } |
| #endif |
| |
| #ifdef HAVE_DHCP6 |
| if (daemon->doing_dhcp6 || daemon->relay6) |
| poll_listen(daemon->dhcp6fd, POLLIN); |
| |
| if (daemon->doing_ra) |
| poll_listen(daemon->icmp6fd, POLLIN); |
| #endif |
| |
| #ifdef HAVE_INOTIFY |
| if (daemon->inotifyfd != -1) |
| poll_listen(daemon->inotifyfd, POLLIN); |
| #endif |
| |
| #if defined(HAVE_LINUX_NETWORK) |
| poll_listen(daemon->netlinkfd, POLLIN); |
| #elif defined(HAVE_BSD_NETWORK) |
| poll_listen(daemon->routefd, POLLIN); |
| #endif |
| |
| poll_listen(piperead, POLLIN); |
| |
| #ifdef HAVE_SCRIPT |
| while (helper_buf_empty() && do_script_run(now)); |
| while (helper_buf_empty() && do_arp_script_run()); |
| |
| # ifdef HAVE_TFTP |
| while (helper_buf_empty() && do_tftp_script_run()); |
| # endif |
| |
| if (!helper_buf_empty()) |
| poll_listen(daemon->helperfd, POLLOUT); |
| #else |
| /* need this for other side-effects */ |
| while (do_script_run(now)); |
| while (do_arp_script_run(now)); |
| |
| # ifdef HAVE_TFTP |
| while (do_tftp_script_run()); |
| # endif |
| |
| #endif |
| |
| |
| /* must do this just before select(), when we know no |
| more calls to my_syslog() can occur */ |
| set_log_writer(); |
| |
| if (do_poll(timeout) < 0) |
| continue; |
| |
| now = dnsmasq_time(); |
| |
| check_log_writer(0); |
| |
| /* prime. */ |
| enumerate_interfaces(1); |
| |
| /* Check the interfaces to see if any have exited DAD state |
| and if so, bind the address. */ |
| if (is_dad_listeners()) |
| { |
| enumerate_interfaces(0); |
| /* NB, is_dad_listeners() == 1 --> we're binding interfaces */ |
| create_bound_listeners(0); |
| warn_bound_listeners(); |
| } |
| |
| #if defined(HAVE_LINUX_NETWORK) |
| if (poll_check(daemon->netlinkfd, POLLIN)) |
| netlink_multicast(); |
| #elif defined(HAVE_BSD_NETWORK) |
| if (poll_check(daemon->routefd, POLLIN)) |
| route_sock(); |
| #endif |
| |
| #ifdef HAVE_INOTIFY |
| if (daemon->inotifyfd != -1 && poll_check(daemon->inotifyfd, POLLIN) && inotify_check(now)) |
| { |
| if (daemon->port != 0 && !option_bool(OPT_NO_POLL)) |
| poll_resolv(1, 1, now); |
| } |
| #else |
| /* Check for changes to resolv files once per second max. */ |
| /* Don't go silent for long periods if the clock goes backwards. */ |
| if (daemon->last_resolv == 0 || |
| difftime(now, daemon->last_resolv) > 1.0 || |
| difftime(now, daemon->last_resolv) < -1.0) |
| { |
| /* poll_resolv doesn't need to reload first time through, since |
| that's queued anyway. */ |
| |
| poll_resolv(0, daemon->last_resolv != 0, now); |
| daemon->last_resolv = now; |
| } |
| #endif |
| |
| if (poll_check(piperead, POLLIN)) |
| async_event(piperead, now); |
| |
| #ifdef HAVE_DBUS |
| /* if we didn't create a DBus connection, retry now. */ |
| if (option_bool(OPT_DBUS) && !daemon->dbus) |
| { |
| char *err; |
| if ((err = dbus_init())) |
| my_syslog(LOG_WARNING, _("DBus error: %s"), err); |
| if (daemon->dbus) |
| my_syslog(LOG_INFO, _("connected to system DBus")); |
| } |
| check_dbus_listeners(); |
| #endif |
| |
| check_dns_listeners(now); |
| |
| #ifdef HAVE_TFTP |
| check_tftp_listeners(now); |
| #endif |
| |
| #ifdef HAVE_DHCP |
| if (daemon->dhcp || daemon->relay4) |
| { |
| if (poll_check(daemon->dhcpfd, POLLIN)) |
| dhcp_packet(now, 0); |
| if (daemon->pxefd != -1 && poll_check(daemon->pxefd, POLLIN)) |
| dhcp_packet(now, 1); |
| } |
| |
| #ifdef HAVE_DHCP6 |
| if ((daemon->doing_dhcp6 || daemon->relay6) && poll_check(daemon->dhcp6fd, POLLIN)) |
| dhcp6_packet(now); |
| |
| if (daemon->doing_ra && poll_check(daemon->icmp6fd, POLLIN)) |
| icmp6_packet(now); |
| #endif |
| |
| # ifdef HAVE_SCRIPT |
| if (daemon->helperfd != -1 && poll_check(daemon->helperfd, POLLOUT)) |
| helper_write(); |
| # endif |
| #endif |
| |
| } |
| } |
| |
| static void sig_handler(int sig) |
| { |
| if (pid == 0) |
| { |
| /* ignore anything other than TERM during startup |
| and in helper proc. (helper ignore TERM too) */ |
| if (sig == SIGTERM) |
| exit(EC_MISC); |
| } |
| else if (pid != getpid()) |
| { |
| /* alarm is used to kill TCP children after a fixed time. */ |
| if (sig == SIGALRM) |
| _exit(0); |
| } |
| else |
| { |
| /* master process */ |
| int event, errsave = errno; |
| |
| if (sig == SIGHUP) |
| event = EVENT_RELOAD; |
| else if (sig == SIGCHLD) |
| event = EVENT_CHILD; |
| else if (sig == SIGALRM) |
| event = EVENT_ALARM; |
| else if (sig == SIGTERM) |
| event = EVENT_TERM; |
| else if (sig == SIGUSR1) |
| event = EVENT_DUMP; |
| else if (sig == SIGUSR2) |
| event = EVENT_REOPEN; |
| else |
| return; |
| |
| send_event(pipewrite, event, 0, NULL); |
| errno = errsave; |
| } |
| } |
| |
| /* now == 0 -> queue immediate callback */ |
| void send_alarm(time_t event, time_t now) |
| { |
| if (now == 0 || event != 0) |
| { |
| /* alarm(0) or alarm(-ve) doesn't do what we want.... */ |
| if ((now == 0 || difftime(event, now) <= 0.0)) |
| send_event(pipewrite, EVENT_ALARM, 0, NULL); |
| else |
| alarm((unsigned)difftime(event, now)); |
| } |
| } |
| |
| void queue_event(int event) |
| { |
| send_event(pipewrite, event, 0, NULL); |
| } |
| |
| void send_event(int fd, int event, int data, char *msg) |
| { |
| struct event_desc ev; |
| struct iovec iov[2]; |
| |
| ev.event = event; |
| ev.data = data; |
| ev.msg_sz = msg ? strlen(msg) : 0; |
| |
| iov[0].iov_base = &ev; |
| iov[0].iov_len = sizeof(ev); |
| iov[1].iov_base = msg; |
| iov[1].iov_len = ev.msg_sz; |
| |
| /* error pipe, debug mode. */ |
| if (fd == -1) |
| fatal_event(&ev, msg); |
| else |
| /* pipe is non-blocking and struct event_desc is smaller than |
| PIPE_BUF, so this either fails or writes everything */ |
| while (writev(fd, iov, msg ? 2 : 1) == -1 && errno == EINTR); |
| } |
| |
| /* NOTE: the memory used to return msg is leaked: use msgs in events only |
| to describe fatal errors. */ |
| static int read_event(int fd, struct event_desc *evp, char **msg) |
| { |
| char *buf; |
| |
| if (!read_write(fd, (unsigned char *)evp, sizeof(struct event_desc), 1)) |
| return 0; |
| |
| *msg = NULL; |
| |
| if (evp->msg_sz != 0 && |
| (buf = malloc(evp->msg_sz + 1)) && |
| read_write(fd, (unsigned char *)buf, evp->msg_sz, 1)) |
| { |
| buf[evp->msg_sz] = 0; |
| *msg = buf; |
| } |
| |
| return 1; |
| } |
| |
| static void fatal_event(struct event_desc *ev, char *msg) |
| { |
| errno = ev->data; |
| |
| switch (ev->event) |
| { |
| case EVENT_DIE: |
| exit(0); |
| |
| case EVENT_FORK_ERR: |
| die(_("cannot fork into background: %s"), NULL, EC_MISC); |
| |
| case EVENT_PIPE_ERR: |
| die(_("failed to create helper: %s"), NULL, EC_MISC); |
| |
| case EVENT_CAP_ERR: |
| die(_("setting capabilities failed: %s"), NULL, EC_MISC); |
| |
| case EVENT_USER_ERR: |
| die(_("failed to change user-id to %s: %s"), msg, EC_MISC); |
| |
| case EVENT_GROUP_ERR: |
| die(_("failed to change group-id to %s: %s"), msg, EC_MISC); |
| |
| case EVENT_PIDFILE: |
| die(_("failed to open pidfile %s: %s"), msg, EC_FILE); |
| |
| case EVENT_LOG_ERR: |
| die(_("cannot open log %s: %s"), msg, EC_FILE); |
| |
| case EVENT_LUA_ERR: |
| die(_("failed to load Lua script: %s"), msg, EC_MISC); |
| |
| case EVENT_TFTP_ERR: |
| die(_("TFTP directory %s inaccessible: %s"), msg, EC_FILE); |
| |
| case EVENT_TIME_ERR: |
| die(_("cannot create timestamp file %s: %s" ), msg, EC_BADCONF); |
| } |
| } |
| |
| static void async_event(int pipe, time_t now) |
| { |
| pid_t p; |
| struct event_desc ev; |
| int i, check = 0; |
| char *msg; |
| |
| /* NOTE: the memory used to return msg is leaked: use msgs in events only |
| to describe fatal errors. */ |
| |
| if (read_event(pipe, &ev, &msg)) |
| switch (ev.event) |
| { |
| case EVENT_RELOAD: |
| #ifdef HAVE_DNSSEC |
| if (option_bool(OPT_DNSSEC_VALID) && option_bool(OPT_DNSSEC_TIME)) |
| { |
| my_syslog(LOG_INFO, _("now checking DNSSEC signature timestamps")); |
| reset_option_bool(OPT_DNSSEC_TIME); |
| } |
| #endif |
| /* fall through */ |
| |
| case EVENT_INIT: |
| clear_cache_and_reload(now); |
| |
| if (daemon->port != 0) |
| { |
| if (daemon->resolv_files && option_bool(OPT_NO_POLL)) |
| { |
| reload_servers(daemon->resolv_files->name); |
| check = 1; |
| } |
| |
| if (daemon->servers_file) |
| { |
| read_servers_file(); |
| check = 1; |
| } |
| |
| if (check) |
| check_servers(); |
| } |
| |
| #ifdef HAVE_DHCP |
| rerun_scripts(); |
| #endif |
| break; |
| |
| case EVENT_DUMP: |
| if (daemon->port != 0) |
| dump_cache(now); |
| break; |
| |
| case EVENT_ALARM: |
| #ifdef HAVE_DHCP |
| if (daemon->dhcp || daemon->doing_dhcp6) |
| { |
| lease_prune(NULL, now); |
| lease_update_file(now); |
| } |
| #ifdef HAVE_DHCP6 |
| else if (daemon->doing_ra) |
| /* Not doing DHCP, so no lease system, manage alarms for ra only */ |
| send_alarm(periodic_ra(now), now); |
| #endif |
| #endif |
| break; |
| |
| case EVENT_CHILD: |
| /* See Stevens 5.10 */ |
| while ((p = waitpid(-1, NULL, WNOHANG)) != 0) |
| if (p == -1) |
| { |
| if (errno != EINTR) |
| break; |
| } |
| else |
| for (i = 0 ; i < MAX_PROCS; i++) |
| if (daemon->tcp_pids[i] == p) |
| daemon->tcp_pids[i] = 0; |
| break; |
| |
| case EVENT_KILLED: |
| my_syslog(LOG_WARNING, _("script process killed by signal %d"), ev.data); |
| break; |
| |
| case EVENT_EXITED: |
| my_syslog(LOG_WARNING, _("script process exited with status %d"), ev.data); |
| break; |
| |
| case EVENT_EXEC_ERR: |
| my_syslog(LOG_ERR, _("failed to execute %s: %s"), |
| daemon->lease_change_command, strerror(ev.data)); |
| break; |
| |
| /* necessary for fatal errors in helper */ |
| case EVENT_USER_ERR: |
| case EVENT_DIE: |
| case EVENT_LUA_ERR: |
| fatal_event(&ev, msg); |
| break; |
| |
| case EVENT_REOPEN: |
| /* Note: this may leave TCP-handling processes with the old file still open. |
| Since any such process will die in CHILD_LIFETIME or probably much sooner, |
| we leave them logging to the old file. */ |
| if (daemon->log_file != NULL) |
| log_reopen(daemon->log_file); |
| break; |
| |
| case EVENT_NEWADDR: |
| newaddress(now); |
| break; |
| |
| case EVENT_NEWROUTE: |
| resend_query(); |
| /* Force re-reading resolv file right now, for luck. */ |
| poll_resolv(0, 1, now); |
| break; |
| |
| case EVENT_TERM: |
| /* Knock all our children on the head. */ |
| for (i = 0; i < MAX_PROCS; i++) |
| if (daemon->tcp_pids[i] != 0) |
| kill(daemon->tcp_pids[i], SIGALRM); |
| |
| #if defined(HAVE_SCRIPT) |
| /* handle pending lease transitions */ |
| if (daemon->helperfd != -1) |
| { |
| /* block in writes until all done */ |
| if ((i = fcntl(daemon->helperfd, F_GETFL)) != -1) |
| fcntl(daemon->helperfd, F_SETFL, i & ~O_NONBLOCK); |
| do { |
| helper_write(); |
| } while (!helper_buf_empty() || do_script_run(now)); |
| while (retry_send(close(daemon->helperfd))); |
| } |
| #endif |
| |
| if (daemon->lease_stream) |
| fclose(daemon->lease_stream); |
| |
| #ifdef HAVE_DNSSEC |
| /* update timestamp file on TERM if time is considered valid */ |
| if (daemon->back_to_the_future) |
| { |
| if (utime(daemon->timestamp_file, NULL) == -1) |
| my_syslog(LOG_ERR, _("failed to update mtime on %s: %s"), daemon->timestamp_file, strerror(errno)); |
| } |
| #endif |
| |
| if (daemon->runfile) |
| unlink(daemon->runfile); |
| |
| my_syslog(LOG_INFO, _("exiting on receipt of SIGTERM")); |
| flush_log(); |
| exit(EC_GOOD); |
| } |
| } |
| |
| static void poll_resolv(int force, int do_reload, time_t now) |
| { |
| struct resolvc *res, *latest; |
| struct stat statbuf; |
| 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. */ |
| |
| if (daemon->port == 0 || option_bool(OPT_NO_POLL)) |
| return; |
| |
| for (latest = NULL, res = daemon->resolv_files; res; res = res->next) |
| if (stat(res->name, &statbuf) == -1) |
| { |
| if (force) |
| { |
| res->mtime = 0; |
| continue; |
| } |
| |
| if (!res->logged) |
| my_syslog(LOG_WARNING, _("failed to access %s: %s"), res->name, strerror(errno)); |
| res->logged = 1; |
| |
| if (res->mtime != 0) |
| { |
| /* existing file evaporated, force selection of the latest |
| file even if its mtime hasn't changed since we last looked */ |
| poll_resolv(1, do_reload, now); |
| return; |
| } |
| } |
| else |
| { |
| res->logged = 0; |
| if (force || (statbuf.st_mtime != res->mtime)) |
| { |
| res->mtime = statbuf.st_mtime; |
| if (difftime(statbuf.st_mtime, last_change) > 0.0) |
| { |
| last_change = statbuf.st_mtime; |
| latest = res; |
| } |
| } |
| } |
| |
| if (latest) |
| { |
| static int warned = 0; |
| if (reload_servers(latest->name)) |
| { |
| my_syslog(LOG_INFO, _("reading %s"), latest->name); |
| warned = 0; |
| check_servers(); |
| if (option_bool(OPT_RELOAD) && do_reload) |
| clear_cache_and_reload(now); |
| } |
| else |
| { |
| latest->mtime = 0; |
| if (!warned) |
| { |
| my_syslog(LOG_WARNING, _("no servers found in %s, will retry"), latest->name); |
| warned = 1; |
| } |
| } |
| } |
| } |
| |
| void clear_cache_and_reload(time_t now) |
| { |
| (void)now; |
| |
| if (daemon->port != 0) |
| cache_reload(); |
| |
| #ifdef HAVE_DHCP |
| if (daemon->dhcp || daemon->doing_dhcp6) |
| { |
| if (option_bool(OPT_ETHERS)) |
| dhcp_read_ethers(); |
| reread_dhcp(); |
| #ifdef HAVE_INOTIFY |
| set_dynamic_inotify(AH_DHCP_HST | AH_DHCP_OPT, 0, NULL, 0); |
| #endif |
| dhcp_update_configs(daemon->dhcp_conf); |
| lease_update_from_configs(); |
| lease_update_file(now); |
| lease_update_dns(1); |
| } |
| #ifdef HAVE_DHCP6 |
| else if (daemon->doing_ra) |
| /* Not doing DHCP, so no lease system, manage |
| alarms for ra only */ |
| send_alarm(periodic_ra(now), now); |
| #endif |
| #endif |
| } |
| |
| static int set_dns_listeners(time_t now) |
| { |
| struct serverfd *serverfdp; |
| struct listener *listener; |
| int wait = 0, i; |
| |
| #ifdef HAVE_TFTP |
| int tftp = 0; |
| struct tftp_transfer *transfer; |
| for (transfer = daemon->tftp_trans; transfer; transfer = transfer->next) |
| { |
| tftp++; |
| poll_listen(transfer->sockfd, POLLIN); |
| } |
| #endif |
| |
| /* will we be able to get memory? */ |
| if (daemon->port != 0) |
| get_new_frec(now, &wait, 0); |
| |
| for (serverfdp = daemon->sfds; serverfdp; serverfdp = serverfdp->next) |
| poll_listen(serverfdp->fd, POLLIN); |
| |
| if (daemon->port != 0 && !daemon->osport) |
| for (i = 0; i < RANDOM_SOCKS; i++) |
| if (daemon->randomsocks[i].refcount != 0) |
| poll_listen(daemon->randomsocks[i].fd, POLLIN); |
| |
| for (listener = daemon->listeners; listener; listener = listener->next) |
| { |
| /* only listen for queries if we have resources */ |
| if (listener->fd != -1 && wait == 0) |
| poll_listen(listener->fd, POLLIN); |
| |
| /* death of a child goes through the select loop, so |
| we don't need to explicitly arrange to wake up here */ |
| if (listener->tcpfd != -1) |
| for (i = 0; i < MAX_PROCS; i++) |
| if (daemon->tcp_pids[i] == 0) |
| { |
| poll_listen(listener->tcpfd, POLLIN); |
| break; |
| } |
| |
| #ifdef HAVE_TFTP |
| if (tftp <= daemon->tftp_max && listener->tftpfd != -1) |
| poll_listen(listener->tftpfd, POLLIN); |
| #endif |
| |
| } |
| |
| return wait; |
| } |
| |
| static void check_dns_listeners(time_t now) |
| { |
| struct serverfd *serverfdp; |
| struct listener *listener; |
| int i; |
| |
| for (serverfdp = daemon->sfds; serverfdp; serverfdp = serverfdp->next) |
| if (poll_check(serverfdp->fd, POLLIN)) |
| reply_query(serverfdp->fd, serverfdp->source_addr.sa.sa_family, now); |
| |
| if (daemon->port != 0 && !daemon->osport) |
| for (i = 0; i < RANDOM_SOCKS; i++) |
| if (daemon->randomsocks[i].refcount != 0 && |
| poll_check(daemon->randomsocks[i].fd, POLLIN)) |
| reply_query(daemon->randomsocks[i].fd, daemon->randomsocks[i].family, now); |
| |
| for (listener = daemon->listeners; listener; listener = listener->next) |
| { |
| if (listener->fd != -1 && poll_check(listener->fd, POLLIN)) |
| receive_query(listener, now); |
| |
| #ifdef HAVE_TFTP |
| if (listener->tftpfd != -1 && poll_check(listener->tftpfd, POLLIN)) |
| tftp_request(listener, now); |
| #endif |
| |
| if (listener->tcpfd != -1 && poll_check(listener->tcpfd, POLLIN)) |
| { |
| int confd, client_ok = 1; |
| struct irec *iface = NULL; |
| pid_t p; |
| union mysockaddr tcp_addr; |
| socklen_t tcp_len = sizeof(union mysockaddr); |
| |
| while ((confd = accept(listener->tcpfd, NULL, NULL)) == -1 && errno == EINTR); |
| |
| if (confd == -1) |
| continue; |
| |
| if (getsockname(confd, (struct sockaddr *)&tcp_addr, &tcp_len) == -1) |
| { |
| while (retry_send(close(confd))); |
| continue; |
| } |
| |
| /* Make sure that the interface list is up-to-date. |
| |
| We do this here as we may need the results below, and |
| the DNS code needs them for --interface-name stuff. |
| |
| Multiple calls to enumerate_interfaces() per select loop are |
| inhibited, so calls to it in the child process (which doesn't select()) |
| have no effect. This avoids two processes reading from the same |
| netlink fd and screwing the pooch entirely. |
| */ |
| |
| enumerate_interfaces(0); |
| |
| if (option_bool(OPT_NOWILD)) |
| iface = listener->iface; /* May be NULL */ |
| else |
| { |
| int if_index; |
| char intr_name[IF_NAMESIZE]; |
| |
| /* if we can find the arrival interface, check it's one that's allowed */ |
| if ((if_index = tcp_interface(confd, tcp_addr.sa.sa_family)) != 0 && |
| indextoname(listener->tcpfd, if_index, intr_name)) |
| { |
| struct all_addr addr; |
| addr.addr.addr4 = tcp_addr.in.sin_addr; |
| #ifdef HAVE_IPV6 |
| if (tcp_addr.sa.sa_family == AF_INET6) |
| addr.addr.addr6 = tcp_addr.in6.sin6_addr; |
| #endif |
| |
| for (iface = daemon->interfaces; iface; iface = iface->next) |
| if (iface->index == if_index) |
| break; |
| |
| if (!iface && !loopback_exception(listener->tcpfd, tcp_addr.sa.sa_family, &addr, intr_name)) |
| client_ok = 0; |
| } |
| |
| if (option_bool(OPT_CLEVERBIND)) |
| iface = listener->iface; /* May be NULL */ |
| else |
| { |
| /* Check for allowed interfaces when binding the wildcard address: |
| we do this by looking for an interface with the same address as |
| the local address of the TCP connection, then looking to see if that's |
| an allowed interface. As a side effect, we get the netmask of the |
| interface too, for localisation. */ |
| |
| for (iface = daemon->interfaces; iface; iface = iface->next) |
| if (sockaddr_isequal(&iface->addr, &tcp_addr)) |
| break; |
| |
| if (!iface) |
| client_ok = 0; |
| } |
| } |
| |
| if (!client_ok) |
| { |
| shutdown(confd, SHUT_RDWR); |
| while (retry_send(close(confd))); |
| } |
| #ifndef NO_FORK |
| else if (!option_bool(OPT_DEBUG) && (p = fork()) != 0) |
| { |
| if (p != -1) |
| { |
| int i; |
| for (i = 0; i < MAX_PROCS; i++) |
| if (daemon->tcp_pids[i] == 0) |
| { |
| daemon->tcp_pids[i] = p; |
| break; |
| } |
| } |
| while (retry_send(close(confd))); |
| |
| /* The child can use up to TCP_MAX_QUERIES ids, so skip that many. */ |
| daemon->log_id += TCP_MAX_QUERIES; |
| } |
| #endif |
| else |
| { |
| unsigned char *buff; |
| struct server *s; |
| int flags; |
| struct in_addr netmask; |
| int auth_dns; |
| |
| if (iface) |
| { |
| netmask = iface->netmask; |
| auth_dns = iface->dns_auth; |
| } |
| else |
| { |
| netmask.s_addr = 0; |
| auth_dns = 0; |
| } |
| |
| #ifndef NO_FORK |
| /* Arrange for SIGALARM after CHILD_LIFETIME seconds to |
| terminate the process. */ |
| if (!option_bool(OPT_DEBUG)) |
| alarm(CHILD_LIFETIME); |
| #endif |
| |
| /* start with no upstream connections. */ |
| for (s = daemon->servers; s; s = s->next) |
| s->tcpfd = -1; |
| |
| /* The connected socket inherits non-blocking |
| attribute from the listening socket. |
| Reset that here. */ |
| if ((flags = fcntl(confd, F_GETFL, 0)) != -1) |
| fcntl(confd, F_SETFL, flags & ~O_NONBLOCK); |
| |
| buff = tcp_request(confd, now, &tcp_addr, netmask, auth_dns); |
| |
| shutdown(confd, SHUT_RDWR); |
| while (retry_send(close(confd))); |
| |
| if (buff) |
| free(buff); |
| |
| for (s = daemon->servers; s; s = s->next) |
| if (s->tcpfd != -1) |
| { |
| shutdown(s->tcpfd, SHUT_RDWR); |
| while (retry_send(close(s->tcpfd))); |
| } |
| #ifndef NO_FORK |
| if (!option_bool(OPT_DEBUG)) |
| { |
| flush_log(); |
| _exit(0); |
| } |
| #endif |
| } |
| } |
| } |
| } |
| |
| #ifdef HAVE_DHCP |
| int make_icmp_sock(void) |
| { |
| int fd; |
| int zeroopt = 0; |
| |
| if ((fd = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP)) != -1) |
| { |
| if (!fix_fd(fd) || |
| setsockopt(fd, SOL_SOCKET, SO_DONTROUTE, &zeroopt, sizeof(zeroopt)) == -1) |
| { |
| close(fd); |
| fd = -1; |
| } |
| } |
| |
| return fd; |
| } |
| |
| int icmp_ping(struct in_addr addr) |
| { |
| /* Try and get an ICMP echo from a machine. */ |
| |
| /* Note that whilst in the three second wait, we check for |
| (and service) events on the DNS and TFTP sockets, (so doing that |
| better not use any resources our caller has in use...) |
| but we remain deaf to signals or further DHCP packets. */ |
| |
| /* There can be a problem using dnsmasq_time() to end the loop, since |
| it's not monotonic, and can go backwards if the system clock is |
| tweaked, leading to the code getting stuck in this loop and |
| ignoring DHCP requests. To fix this, we check to see if select returned |
| as a result of a timeout rather than a socket becoming available. We |
| only allow this to happen as many times as it takes to get to the wait time |
| in quarter-second chunks. This provides a fallback way to end loop. */ |
| |
| int fd, rc; |
| struct sockaddr_in saddr; |
| struct { |
| struct ip ip; |
| struct icmp icmp; |
| } packet; |
| unsigned short id = rand16(); |
| unsigned int i, j, timeout_count; |
| int gotreply = 0; |
| time_t start, now; |
| |
| #if defined(HAVE_LINUX_NETWORK) || defined (HAVE_SOLARIS_NETWORK) |
| if ((fd = make_icmp_sock()) == -1) |
| return 0; |
| #else |
| int opt = 2000; |
| fd = daemon->dhcp_icmp_fd; |
| setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &opt, sizeof(opt)); |
| #endif |
| |
| saddr.sin_family = AF_INET; |
| saddr.sin_port = 0; |
| saddr.sin_addr = addr; |
| #ifdef HAVE_SOCKADDR_SA_LEN |
| saddr.sin_len = sizeof(struct sockaddr_in); |
| #endif |
| |
| memset(&packet.icmp, 0, sizeof(packet.icmp)); |
| packet.icmp.icmp_type = ICMP_ECHO; |
| packet.icmp.icmp_id = id; |
| for (j = 0, i = 0; i < sizeof(struct icmp) / 2; i++) |
| j += ((u16 *)&packet.icmp)[i]; |
| while (j>>16) |
| j = (j & 0xffff) + (j >> 16); |
| packet.icmp.icmp_cksum = (j == 0xffff) ? j : ~j; |
| |
| while (retry_send(sendto(fd, (char *)&packet.icmp, sizeof(struct icmp), 0, |
| (struct sockaddr *)&saddr, sizeof(saddr)))); |
| |
| for (now = start = dnsmasq_time(), timeout_count = 0; |
| (difftime(now, start) < (float)PING_WAIT) && (timeout_count < PING_WAIT * 4);) |
| { |
| struct sockaddr_in faddr; |
| socklen_t len = sizeof(faddr); |
| |
| poll_reset(); |
| poll_listen(fd, POLLIN); |
| set_dns_listeners(now); |
| set_log_writer(); |
| |
| #ifdef HAVE_DHCP6 |
| if (daemon->doing_ra) |
| poll_listen(daemon->icmp6fd, POLLIN); |
| #endif |
| |
| rc = do_poll(250); |
| |
| if (rc < 0) |
| continue; |
| else if (rc == 0) |
| timeout_count++; |
| |
| now = dnsmasq_time(); |
| |
| check_log_writer(0); |
| check_dns_listeners(now); |
| |
| #ifdef HAVE_DHCP6 |
| if (daemon->doing_ra && poll_check(daemon->icmp6fd, POLLIN)) |
| icmp6_packet(now); |
| #endif |
| |
| #ifdef HAVE_TFTP |
| check_tftp_listeners(now); |
| #endif |
| |
| if (poll_check(fd, POLLIN) && |
| recvfrom(fd, &packet, sizeof(packet), 0, |
| (struct sockaddr *)&faddr, &len) == sizeof(packet) && |
| saddr.sin_addr.s_addr == faddr.sin_addr.s_addr && |
| packet.icmp.icmp_type == ICMP_ECHOREPLY && |
| packet.icmp.icmp_seq == 0 && |
| packet.icmp.icmp_id == id) |
| { |
| gotreply = 1; |
| break; |
| } |
| } |
| |
| #if defined(HAVE_LINUX_NETWORK) || defined(HAVE_SOLARIS_NETWORK) |
| while (retry_send(close(fd))); |
| #else |
| opt = 1; |
| setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &opt, sizeof(opt)); |
| #endif |
| |
| return gotreply; |
| } |
| #endif |
| |
| |