9
9
* "browse_callback", and parts of "main".
11
11
* Everything else is
12
* Copyright © 2008-2012 Teddy Hogeborn
13
* Copyright © 2008-2012 Björn Påhlsson
12
* Copyright © 2008-2013 Teddy Hogeborn
13
* Copyright © 2008-2013 Björn Påhlsson
15
15
* This program is free software: you can redistribute it and/or
16
16
* modify it under the terms of the GNU General Public License as
56
56
#include <sys/stat.h> /* open(), S_ISREG */
57
57
#include <sys/socket.h> /* socket(), struct sockaddr_in6,
58
inet_pton(), connect() */
58
inet_pton(), connect(),
59
60
#include <fcntl.h> /* open() */
60
61
#include <dirent.h> /* opendir(), struct dirent, readdir()
73
74
#include <unistd.h> /* close(), SEEK_SET, off_t, write(),
74
75
getuid(), getgid(), seteuid(),
75
76
setgid(), pause(), _exit() */
76
#include <arpa/inet.h> /* inet_pton(), htons, inet_ntop() */
77
#include <arpa/inet.h> /* inet_pton(), htons() */
77
78
#include <iso646.h> /* not, or, and */
78
79
#include <argp.h> /* struct argp_option, error_t, struct
79
80
argp_state, struct argp,
91
92
argz_delete(), argz_append(),
92
93
argz_stringify(), argz_add(),
95
#include <netdb.h> /* getnameinfo(), NI_NUMERICHOST,
96
EAI_SYSTEM, gai_strerror() */
96
99
#include <sys/klog.h> /* klogctl() */
134
137
bool debug = false;
135
138
static const char mandos_protocol_version[] = "1";
136
const char *argp_program_version = "mandos-client " VERSION;
137
const char *argp_program_bug_address = "<mandos@recompile.se>";
139
const char * argp_program_version = "mandos-client " VERSION;
140
const char * argp_program_bug_address = "<mandos@recompile.se>";
138
141
static const char sys_class_net[] = "/sys/class/net";
139
142
char *connect_to = NULL;
140
143
const char *hookdir = HOOKDIR;
178
183
perror(print_text);
181
__attribute__((format (gnu_printf, 2, 3)))
186
__attribute__((format (gnu_printf, 2, 3), nonnull))
182
187
int fprintf_plus(FILE *stream, const char *format, ...){
184
189
va_start (ap, format);
186
191
TEMP_FAILURE_RETRY(fprintf(stream, "Mandos plugin %s: ",
187
192
program_invocation_short_name));
188
return TEMP_FAILURE_RETRY(vfprintf(stream, format, ap));
193
return (int)TEMP_FAILURE_RETRY(vfprintf(stream, format, ap));
193
198
* bytes. "buffer_capacity" is how much is currently allocated,
194
199
* "buffer_length" is how much is already used.
201
__attribute__((nonnull, warn_unused_result))
196
202
size_t incbuffer(char **buffer, size_t buffer_length,
197
203
size_t buffer_capacity){
198
204
if(buffer_length + BUFFER_SIZE > buffer_capacity){
199
*buffer = realloc(*buffer, buffer_capacity + BUFFER_SIZE);
205
char *new_buf = realloc(*buffer, buffer_capacity + BUFFER_SIZE);
207
int old_errno = errno;
203
214
buffer_capacity += BUFFER_SIZE;
205
216
return buffer_capacity;
208
219
/* Add server to set of servers to retry periodically */
220
__attribute__((nonnull, warn_unused_result))
209
221
bool add_server(const char *ip, in_port_t port, AvahiIfIndex if_index,
210
222
int af, server **current_server){
222
234
perror_plus("strdup");
237
ret = clock_gettime(CLOCK_MONOTONIC, &(new_server->last_seen));
239
perror_plus("clock_gettime");
225
242
/* Special case of first server */
226
243
if(*current_server == NULL){
227
244
new_server->next = new_server;
228
245
new_server->prev = new_server;
229
246
*current_server = new_server;
230
/* Place the new server last in the list */
248
/* Place the new server last in the list */
232
249
new_server->next = *current_server;
233
250
new_server->prev = (*current_server)->prev;
234
251
new_server->prev->next = new_server;
235
252
(*current_server)->prev = new_server;
237
ret = clock_gettime(CLOCK_MONOTONIC, &(*current_server)->last_seen);
239
perror_plus("clock_gettime");
246
258
* Initialize GPGME.
248
static bool init_gpgme(const char *seckey, const char *pubkey,
249
const char *tempdir, mandos_context *mc){
260
__attribute__((nonnull, warn_unused_result))
261
static bool init_gpgme(const char * const seckey,
262
const char * const pubkey,
263
const char * const tempdir,
250
265
gpgme_error_t rc;
251
266
gpgme_engine_info_t engine_info;
254
269
* Helper function to insert pub and seckey to the engine keyring.
256
bool import_key(const char *filename){
271
bool import_key(const char * const filename){
259
274
gpgme_data_t pgp_data;
475
492
/* GnuTLS log function callback */
493
__attribute__((nonnull))
476
494
static void debuggnutls(__attribute__((unused)) int level,
477
495
const char* string){
478
496
fprintf_plus(stderr, "GnuTLS: %s", string);
499
__attribute__((nonnull, warn_unused_result))
481
500
static int init_gnutls_global(const char *pubkeyfilename,
482
501
const char *seckeyfilename,
483
502
mandos_context *mc){
619
639
__attribute__((unused)) const char *txt){}
621
641
/* Called when a Mandos server is found */
642
__attribute__((nonnull, warn_unused_result))
622
643
static int start_mandos_communication(const char *ip, in_port_t port,
623
644
AvahiIfIndex if_index,
624
645
int af, mandos_context *mc){
625
646
int ret, tcp_sd = -1;
628
struct sockaddr_in in;
629
struct sockaddr_in6 in6;
648
struct sockaddr_storage to;
631
649
char *buffer = NULL;
632
650
char *decrypted_buffer = NULL;
633
651
size_t buffer_length = 0;
678
/* If the interface is specified and we have a list of interfaces */
679
if(if_index != AVAHI_IF_UNSPEC and mc->interfaces != NULL){
680
/* Check if the interface is one of the interfaces we are using */
683
char *interface = NULL;
684
while((interface=argz_next(mc->interfaces, mc->interfaces_size,
686
if(if_nametoindex(interface) == (unsigned int)if_index){
693
/* This interface does not match any in the list, so we don't
694
connect to the server */
696
char interface[IF_NAMESIZE];
697
if(if_indextoname((unsigned int)if_index, interface) == NULL){
698
perror_plus("if_indextoname");
700
fprintf_plus(stderr, "Skipping server on non-used interface"
702
if_indextoname((unsigned int)if_index,
660
710
ret = init_gnutls_session(&session, mc);
683
733
memset(&to, 0, sizeof(to));
684
734
if(af == AF_INET6){
685
to.in6.sin6_family = (sa_family_t)af;
686
ret = inet_pton(af, ip, &to.in6.sin6_addr);
735
((struct sockaddr_in6 *)&to)->sin6_family = (sa_family_t)af;
736
ret = inet_pton(af, ip, &((struct sockaddr_in6 *)&to)->sin6_addr);
687
737
} else { /* IPv4 */
688
to.in.sin_family = (sa_family_t)af;
689
ret = inet_pton(af, ip, &to.in.sin_addr);
738
((struct sockaddr_in *)&to)->sin_family = (sa_family_t)af;
739
ret = inet_pton(af, ip, &((struct sockaddr_in *)&to)->sin_addr);
703
753
if(af == AF_INET6){
704
to.in6.sin6_port = htons(port);
705
if(IN6_IS_ADDR_LINKLOCAL /* Spurious warnings from */
706
(&to.in6.sin6_addr)){ /* -Wstrict-aliasing=2 or lower and
754
((struct sockaddr_in6 *)&to)->sin6_port = htons(port);
755
if(IN6_IS_ADDR_LINKLOCAL
756
(&((struct sockaddr_in6 *)&to)->sin6_addr)){
708
757
if(if_index == AVAHI_IF_UNSPEC){
709
758
fprintf_plus(stderr, "An IPv6 link-local address is"
710
759
" incomplete without a network interface\n");
741
788
char addrstr[(INET_ADDRSTRLEN > INET6_ADDRSTRLEN) ?
742
789
INET_ADDRSTRLEN : INET6_ADDRSTRLEN] = "";
744
790
if(af == AF_INET6){
745
pcret = inet_ntop(af, &(to.in6.sin6_addr), addrstr,
791
ret = getnameinfo((struct sockaddr *)&to,
792
sizeof(struct sockaddr_in6),
793
addrstr, sizeof(addrstr), NULL, 0,
748
pcret = inet_ntop(af, &(to.in.sin_addr), addrstr,
796
ret = getnameinfo((struct sockaddr *)&to,
797
sizeof(struct sockaddr_in),
798
addrstr, sizeof(addrstr), NULL, 0,
752
perror_plus("inet_ntop");
754
if(strcmp(addrstr, ip) != 0){
755
fprintf_plus(stderr, "Canonical address form: %s\n", addrstr);
801
if(ret == EAI_SYSTEM){
802
perror_plus("getnameinfo");
803
} else if(ret != 0) {
804
fprintf_plus(stderr, "getnameinfo: %s", gai_strerror(ret));
805
} else if(strcmp(addrstr, ip) != 0){
806
fprintf_plus(stderr, "Canonical address form: %s\n", addrstr);
765
815
if(af == AF_INET6){
766
ret = connect(tcp_sd, &to.in6, sizeof(to));
816
ret = connect(tcp_sd, (struct sockaddr *)&to,
817
sizeof(struct sockaddr_in6));
768
ret = connect(tcp_sd, &to.in, sizeof(to)); /* IPv4 */
819
ret = connect(tcp_sd, (struct sockaddr *)&to, /* IPv4 */
820
sizeof(struct sockaddr_in));
771
if ((errno != ECONNREFUSED and errno != ENETUNREACH) or debug){
823
if((errno != ECONNREFUSED and errno != ENETUNREACH) or debug){
773
825
perror_plus("connect");
1447
1512
return ret_errno;
1450
bool run_network_hooks(const char *mode, const char *interface,
1515
__attribute__((nonnull))
1516
void run_network_hooks(const char *mode, const char *interface,
1451
1517
const float delay){
1452
1518
struct dirent **direntries;
1453
struct dirent *direntry;
1455
1519
int numhooks = scandir(hookdir, &direntries, runnable_hook,
1457
1521
if(numhooks == -1){
1481
1547
if(hook_pid == 0){
1483
1549
/* Raise privileges */
1484
raise_privileges_permanently();
1550
if(raise_privileges_permanently() != 0){
1551
perror_plus("Failed to raise privileges");
1485
1554
/* Set group */
1487
1556
ret = setgid(0);
1489
1558
perror_plus("setgid");
1491
1561
/* Reset supplementary groups */
1493
1563
ret = setgroups(0, NULL);
1495
1565
perror_plus("setgroups");
1497
dup2(devnull, STDIN_FILENO);
1499
dup2(STDERR_FILENO, STDOUT_FILENO);
1568
ret = dup2(devnull, STDIN_FILENO);
1570
perror_plus("dup2(devnull, STDIN_FILENO)");
1573
ret = close(devnull);
1575
perror_plus("close");
1578
ret = dup2(STDERR_FILENO, STDOUT_FILENO);
1580
perror_plus("dup2(STDERR_FILENO, STDOUT_FILENO)");
1500
1583
ret = setenv("MANDOSNETHOOKDIR", hookdir, 1);
1502
1585
perror_plus("setenv");
1602
1683
if(not interface_is_up(interface)){
1603
if(not get_flags(interface, &network) and debug){
1684
error_t ret_errno = 0, ioctl_errno = 0;
1685
if(not get_flags(interface, &network)){
1604
1686
ret_errno = errno;
1605
1687
fprintf_plus(stderr, "Failed to get flags for interface "
1606
1688
"\"%s\"\n", interface);
1607
1690
return ret_errno;
1609
network.ifr_flags |= IFF_UP;
1692
network.ifr_flags |= IFF_UP; /* set flag */
1611
sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
1694
int sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
1613
1696
ret_errno = errno;
1614
1697
perror_plus("socket");
1615
1698
errno = old_errno;
1616
1699
return ret_errno;
1703
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1705
perror_plus("close");
1621
1707
errno = old_errno;
1630
/* Raise priviliges */
1716
/* Raise privileges */
1717
ret_errno = raise_privileges();
1718
bool restore_loglevel = false;
1720
perror_plus("Failed to raise privileges");
1633
1722
#ifdef __linux__
1634
/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
1635
messages about the network interface to mess up the prompt */
1636
int ret_linux = klogctl(8, NULL, 5);
1637
bool restore_loglevel = true;
1638
if(ret_linux == -1){
1639
restore_loglevel = false;
1640
perror_plus("klogctl");
1725
/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
1726
messages about the network interface to mess up the prompt */
1727
ret_linux = klogctl(8, NULL, 5);
1728
if(ret_linux == -1){
1729
perror_plus("klogctl");
1731
restore_loglevel = true;
1642
1734
#endif /* __linux__ */
1643
ret_setflags = ioctl(sd, SIOCSIFFLAGS, &network);
1735
int ret_setflags = ioctl(sd, SIOCSIFFLAGS, &network);
1736
ioctl_errno = errno;
1645
1737
#ifdef __linux__
1646
1738
if(restore_loglevel){
1647
1739
ret_linux = klogctl(7, NULL, 0);
1703
1800
if(interface_is_up(interface)){
1801
error_t ret_errno = 0, ioctl_errno = 0;
1704
1802
if(not get_flags(interface, &network) and debug){
1705
1803
ret_errno = errno;
1706
1804
fprintf_plus(stderr, "Failed to get flags for interface "
1707
1805
"\"%s\"\n", interface);
1708
1807
return ret_errno;
1710
1809
network.ifr_flags &= ~(short)IFF_UP; /* clear flag */
1712
sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
1811
int sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
1714
1813
ret_errno = errno;
1715
1814
perror_plus("socket");
1716
1815
errno = old_errno;
1725
/* Raise priviliges */
1728
ret_setflags = ioctl(sd, SIOCSIFFLAGS, &network);
1731
/* Lower privileges */
1824
/* Raise privileges */
1825
ret_errno = raise_privileges();
1827
perror_plus("Failed to raise privileges");
1829
int ret_setflags = ioctl(sd, SIOCSIFFLAGS, &network);
1830
ioctl_errno = errno;
1832
/* If raise_privileges() succeeded above */
1834
/* Lower privileges */
1835
ret_errno = lower_privileges();
1838
perror_plus("Failed to lower privileges");
1734
1842
/* Close the socket */
1735
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1843
int ret = (int)TEMP_FAILURE_RETRY(close(sd));
1737
1845
perror_plus("close");
1740
1848
if(ret_setflags == -1){
1849
errno = ioctl_errno;
1742
1850
perror_plus("ioctl SIOCSIFFLAGS -IFF_UP");
1743
1851
errno = old_errno;
1746
1854
} else if(debug){
1747
1855
fprintf_plus(stderr, "Interface \"%s\" is already down; odd\n",
1755
1863
int main(int argc, char *argv[]){
1756
1864
mandos_context mc = { .server = NULL, .dh_bits = 1024,
1757
1865
.priority = "SECURE256:!CTYPE-X.509:"
1758
"+CTYPE-OPENPGP", .current_server = NULL };
1866
"+CTYPE-OPENPGP", .current_server = NULL,
1867
.interfaces = NULL, .interfaces_size = 0 };
1759
1868
AvahiSServiceBrowser *sb = NULL;
1760
1869
error_t ret_errno;
1762
1871
intmax_t tmpmax;
1764
1873
int exitcode = EXIT_SUCCESS;
1765
char *interfaces = NULL;
1766
size_t interfaces_size = 0;
1767
1874
char *interfaces_to_take_down = NULL;
1768
1875
size_t interfaces_to_take_down_size = 0;
1769
char tempdir[] = "/tmp/mandosXXXXXX";
1770
bool tempdir_created = false;
1876
char run_tempdir[] = "/run/tmp/mandosXXXXXX";
1877
char old_tempdir[] = "/tmp/mandosXXXXXX";
1878
char *tempdir = NULL;
1771
1879
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
1772
1880
const char *seckey = PATHDIR "/" SECKEY;
1773
1881
const char *pubkey = PATHDIR "/" PUBKEY;
1774
1882
char *interfaces_hooks = NULL;
1775
size_t interfaces_hooks_size = 0;
1777
1884
bool gnutls_initialized = false;
1778
1885
bool gpgme_initialized = false;
1869
1976
connect_to = arg;
1871
1978
case 'i': /* --interface */
1872
ret_errno = argz_add_sep(&interfaces, &interfaces_size, arg,
1979
ret_errno = argz_add_sep(&mc.interfaces, &mc.interfaces_size,
1874
1981
if(ret_errno != 0){
1875
1982
argp_error(state, "%s", strerror(ret_errno));
1956
2063
/* Work around Debian bug #633582:
1957
2064
<http://bugs.debian.org/633582> */
1959
/* Re-raise priviliges */
1960
if(raise_privileges() == 0){
2066
/* Re-raise privileges */
2067
ret_errno = raise_privileges();
2070
perror_plus("Failed to raise privileges");
1961
2072
struct stat st;
1963
2074
if(strcmp(seckey, PATHDIR "/" SECKEY) == 0){
2005
2116
/* Lower privileges */
2009
perror_plus("seteuid");
2117
ret_errno = lower_privileges();
2120
perror_plus("Failed to lower privileges");
2014
/* Remove empty interface names */
2125
/* Remove invalid interface names (except "none") */
2016
2127
char *interface = NULL;
2017
while((interface = argz_next(interfaces, interfaces_size,
2128
while((interface = argz_next(mc.interfaces, mc.interfaces_size,
2019
if(if_nametoindex(interface) == 0){
2020
if(interface[0] != '\0' and strcmp(interface, "none") != 0){
2130
if(strcmp(interface, "none") != 0
2131
and if_nametoindex(interface) == 0){
2132
if(interface[0] != '\0'){
2021
2133
fprintf_plus(stderr, "Not using nonexisting interface"
2022
2134
" \"%s\"\n", interface);
2024
argz_delete(&interfaces, &interfaces_size, interface);
2136
argz_delete(&mc.interfaces, &mc.interfaces_size, interface);
2025
2137
interface = NULL;
2030
2142
/* Run network hooks */
2033
if(interfaces != NULL){
2034
interfaces_hooks = malloc(interfaces_size);
2144
if(mc.interfaces != NULL){
2145
interfaces_hooks = malloc(mc.interfaces_size);
2035
2146
if(interfaces_hooks == NULL){
2036
2147
perror_plus("malloc");
2039
memcpy(interfaces_hooks, interfaces, interfaces_size);
2040
interfaces_hooks_size = interfaces_size;
2041
argz_stringify(interfaces_hooks, interfaces_hooks_size,
2044
if(not run_network_hooks("start", interfaces_hooks != NULL ?
2045
interfaces_hooks : "", delay)){
2150
memcpy(interfaces_hooks, mc.interfaces, mc.interfaces_size);
2151
argz_stringify(interfaces_hooks, mc.interfaces_size, (int)',');
2153
run_network_hooks("start", interfaces_hooks != NULL ?
2154
interfaces_hooks : "", delay);
2129
2236
/* If no interfaces were specified, make a list */
2130
if(interfaces == NULL){
2237
if(mc.interfaces == NULL){
2131
2238
struct dirent **direntries;
2132
2239
/* Look for any good interfaces */
2133
2240
ret = scandir(sys_class_net, &direntries, good_interface,
2158
/* If we only got one interface, explicitly use only that one */
2159
if(argz_count(interfaces, interfaces_size) == 1){
2161
fprintf_plus(stderr, "Using only interface \"%s\"\n",
2164
if_index = (AvahiIfIndex)if_nametoindex(interfaces);
2167
/* Bring up interfaces which are down */
2168
if(not (argz_count(interfaces, interfaces_size) == 1
2169
and strcmp(interfaces, "none") == 0)){
2266
/* Bring up interfaces which are down, and remove any "none"s */
2170
2268
char *interface = NULL;
2171
while((interface = argz_next(interfaces, interfaces_size,
2269
while((interface = argz_next(mc.interfaces, mc.interfaces_size,
2271
/* If interface name is "none", stop bringing up interfaces.
2272
Also remove all instances of "none" from the list */
2273
if(strcmp(interface, "none") == 0){
2274
argz_delete(&mc.interfaces, &mc.interfaces_size,
2277
while((interface = argz_next(mc.interfaces,
2278
mc.interfaces_size, interface))){
2279
if(strcmp(interface, "none") == 0){
2280
argz_delete(&mc.interfaces, &mc.interfaces_size,
2173
2287
bool interface_was_up = interface_is_up(interface);
2174
ret = bring_up_interface(interface, delay);
2288
errno = bring_up_interface(interface, delay);
2175
2289
if(not interface_was_up){
2178
2291
perror_plus("Failed to bring up interface");
2180
ret_errno = argz_add(&interfaces_to_take_down,
2181
&interfaces_to_take_down_size,
2293
errno = argz_add(&interfaces_to_take_down,
2294
&interfaces_to_take_down_size,
2297
perror_plus("argz_add");
2188
interfaces_size = 0;
2189
2302
if(debug and (interfaces_to_take_down == NULL)){
2190
2303
fprintf_plus(stderr, "No interfaces were brought up\n");
2307
/* If we only got one interface, explicitly use only that one */
2308
if(argz_count(mc.interfaces, mc.interfaces_size) == 1){
2310
fprintf_plus(stderr, "Using only interface \"%s\"\n",
2313
if_index = (AvahiIfIndex)if_nametoindex(mc.interfaces);
2211
if(mkdtemp(tempdir) == NULL){
2333
/* Try /run/tmp before /tmp */
2334
tempdir = mkdtemp(run_tempdir);
2335
if(tempdir == NULL and errno == ENOENT){
2337
fprintf_plus(stderr, "Tempdir %s did not work, trying %s\n",
2338
run_tempdir, old_tempdir);
2340
tempdir = mkdtemp(old_tempdir);
2342
if(tempdir == NULL){
2212
2343
perror_plus("mkdtemp");
2215
tempdir_created = true;
2402
/* Re-raise priviliges */
2534
/* Re-raise privileges */
2406
/* Run network hooks */
2407
run_network_hooks("stop", interfaces_hooks != NULL ?
2408
interfaces_hooks : "", delay);
2410
/* Take down the network interfaces which were brought up */
2412
char *interface = NULL;
2413
while((interface=argz_next(interfaces_to_take_down,
2414
interfaces_to_take_down_size,
2416
ret_errno = take_down_interface(interface);
2419
perror_plus("Failed to take down interface");
2422
if(debug and (interfaces_to_take_down == NULL)){
2423
fprintf_plus(stderr, "No interfaces needed to be taken"
2428
lower_privileges_permanently();
2536
ret_errno = raise_privileges();
2538
perror_plus("Failed to raise privileges");
2541
/* Run network hooks */
2542
run_network_hooks("stop", interfaces_hooks != NULL ?
2543
interfaces_hooks : "", delay);
2545
/* Take down the network interfaces which were brought up */
2547
char *interface = NULL;
2548
while((interface=argz_next(interfaces_to_take_down,
2549
interfaces_to_take_down_size,
2551
ret_errno = take_down_interface(interface);
2554
perror_plus("Failed to take down interface");
2557
if(debug and (interfaces_to_take_down == NULL)){
2558
fprintf_plus(stderr, "No interfaces needed to be taken"
2563
ret_errno = lower_privileges_permanently();
2565
perror_plus("Failed to lower privileges permanently");
2431
2569
free(interfaces_to_take_down);
2432
2570
free(interfaces_hooks);
2434
2572
/* Removes the GPGME temp directory and all files inside */
2435
if(tempdir_created){
2573
if(tempdir != NULL){
2436
2574
struct dirent **direntries = NULL;
2437
2575
struct dirent *direntry = NULL;
2438
2576
int numentries = scandir(tempdir, &direntries, notdotentries,
2440
if (numentries > 0){
2441
2579
for(int i = 0; i < numentries; i++){
2442
2580
direntry = direntries[i];
2443
2581
char *fullname = NULL;