]>
git.ipfire.org Git - thirdparty/systemd.git/blob - src/nss-myhostname/nss-myhostname.c
1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
9 #include "alloc-util.h"
10 #include "errno-util.h"
11 #include "hostname-util.h"
12 #include "local-addresses.h"
15 #include "resolve-util.h"
16 #include "signal-util.h"
17 #include "socket-util.h"
18 #include "string-util.h"
20 /* We use 127.0.0.2 as IPv4 address. This has the advantage over
21 * 127.0.0.1 that it can be translated back to the local hostname. For
22 * IPv6 we use ::1 which unfortunately will not translate back to the
23 * hostname but instead something like "localhost" or so. */
25 #define LOCALADDRESS_IPV4 (htobe32(INADDR_LOCALADDRESS))
26 #define LOCALADDRESS_IPV6 &in6addr_loopback
28 NSS_GETHOSTBYNAME_PROTOTYPES(myhostname
);
29 NSS_GETHOSTBYADDR_PROTOTYPES(myhostname
);
31 enum nss_status
_nss_myhostname_gethostbyname4_r(
33 struct gaih_addrtuple
**pat
,
34 char *buffer
, size_t buflen
,
35 int *errnop
, int *h_errnop
,
38 struct gaih_addrtuple
*r_tuple
, *r_tuple_prev
= NULL
;
39 _cleanup_free_
struct local_address
*addresses
= NULL
;
40 _cleanup_free_
char *hn
= NULL
;
41 const char *canonical
= NULL
;
43 uint32_t local_address_ipv4
;
48 BLOCK_SIGNALS(NSS_SIGNALS_BLOCK
);
56 if (is_localhost(name
)) {
57 /* We respond to 'localhost', so that /etc/hosts is optional */
59 canonical
= "localhost";
60 local_address_ipv4
= htobe32(INADDR_LOOPBACK
);
62 } else if (is_gateway_hostname(name
)) {
64 n_addresses
= local_gateways(NULL
, 0, AF_UNSPEC
, &addresses
);
68 canonical
= "_gateway";
70 } else if (is_outbound_hostname(name
)) {
72 n_addresses
= local_outbounds(NULL
, 0, AF_UNSPEC
, &addresses
);
76 canonical
= "_outbound";
79 hn
= gethostname_malloc();
83 *h_errnop
= NO_RECOVERY
;
84 return NSS_STATUS_TRYAGAIN
;
87 /* We respond to our local hostname, our hostname suffixed with a single dot. */
88 if (!streq(name
, hn
) && !streq_ptr(startswith(name
, hn
), "."))
91 n_addresses
= local_addresses(NULL
, 0, AF_UNSPEC
, &addresses
);
96 local_address_ipv4
= LOCALADDRESS_IPV4
;
99 l
= strlen(canonical
);
100 ms
= ALIGN(l
+1) + ALIGN(sizeof(struct gaih_addrtuple
)) * (n_addresses
> 0 ? n_addresses
: 1 + socket_ipv6_is_enabled());
104 *h_errnop
= NETDB_INTERNAL
;
105 return NSS_STATUS_TRYAGAIN
;
108 /* First, fill in hostname */
110 memcpy(r_name
, canonical
, l
+1);
113 assert(n_addresses
>= 0);
114 if (n_addresses
== 0) {
115 /* Second, fill in IPv6 tuple */
116 if (socket_ipv6_is_enabled()) {
117 r_tuple
= (struct gaih_addrtuple
*) (buffer
+ idx
);
118 r_tuple
->next
= r_tuple_prev
;
119 r_tuple
->name
= r_name
;
120 r_tuple
->family
= AF_INET6
;
121 memcpy(r_tuple
->addr
, LOCALADDRESS_IPV6
, 16);
122 r_tuple
->scopeid
= 0;
124 idx
+= ALIGN(sizeof(struct gaih_addrtuple
));
125 r_tuple_prev
= r_tuple
;
128 /* Third, fill in IPv4 tuple */
129 r_tuple
= (struct gaih_addrtuple
*) (buffer
+ idx
);
130 r_tuple
->next
= r_tuple_prev
;
131 r_tuple
->name
= r_name
;
132 r_tuple
->family
= AF_INET
;
133 *(uint32_t*) r_tuple
->addr
= local_address_ipv4
;
134 r_tuple
->scopeid
= 0;
136 idx
+= ALIGN(sizeof(struct gaih_addrtuple
));
137 r_tuple_prev
= r_tuple
;
140 /* Fourth, fill actual addresses in, but in backwards order */
141 for (int i
= n_addresses
; i
> 0; i
--) {
142 struct local_address
*a
= addresses
+ i
- 1;
144 r_tuple
= (struct gaih_addrtuple
*) (buffer
+ idx
);
145 r_tuple
->next
= r_tuple_prev
;
146 r_tuple
->name
= r_name
;
147 r_tuple
->family
= a
->family
;
148 r_tuple
->scopeid
= a
->family
== AF_INET6
&& in6_addr_is_link_local(&a
->address
.in6
) ? a
->ifindex
: 0;
149 memcpy(r_tuple
->addr
, &a
->address
, 16);
151 idx
+= ALIGN(sizeof(struct gaih_addrtuple
));
152 r_tuple_prev
= r_tuple
;
155 /* Verify the size matches */
158 /* Nscd expects us to store the first record in **pat. */
160 **pat
= *r_tuple_prev
;
167 /* Explicitly reset both *h_errnop and h_errno to work around
168 * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
169 *h_errnop
= NETDB_SUCCESS
;
172 return NSS_STATUS_SUCCESS
;
175 *h_errnop
= HOST_NOT_FOUND
;
176 return NSS_STATUS_NOTFOUND
;
179 static enum nss_status
fill_in_hostent(
180 const char *canonical
, const char *additional
,
182 struct local_address
*addresses
, unsigned n_addresses
,
183 uint32_t local_address_ipv4
,
184 struct hostent
*result
,
185 char *buffer
, size_t buflen
,
186 int *errnop
, int *h_errnop
,
190 size_t l_canonical
, l_additional
, idx
, ms
, alen
;
191 char *r_addr
, *r_name
, *r_aliases
, *r_alias
= NULL
, *r_addr_list
;
192 struct local_address
*a
;
196 assert(IN_SET(af
, AF_INET
, AF_INET6
));
204 alen
= FAMILY_ADDRESS_SIZE(af
);
206 for (a
= addresses
, n
= 0, c
= 0; n
< n_addresses
; a
++, n
++)
210 l_canonical
= strlen(canonical
);
211 l_additional
= strlen_ptr(additional
);
212 ms
= ALIGN(l_canonical
+1)+
213 (additional
? ALIGN(l_additional
+1) : 0) +
215 (additional
? sizeof(char*) : 0) +
216 (c
> 0 ? c
: af
== AF_INET
? 1 : socket_ipv6_is_enabled()) * ALIGN(alen
) +
217 (c
> 0 ? c
+1 : af
== AF_INET
? 2 : (unsigned) socket_ipv6_is_enabled() + 1) * sizeof(char*);
222 *h_errnop
= NETDB_INTERNAL
;
223 return NSS_STATUS_TRYAGAIN
;
226 /* First, fill in hostnames */
228 memcpy(r_name
, canonical
, l_canonical
+1);
229 idx
= ALIGN(l_canonical
+1);
232 r_alias
= buffer
+ idx
;
233 memcpy(r_alias
, additional
, l_additional
+1);
234 idx
+= ALIGN(l_additional
+1);
237 /* Second, create aliases array */
238 r_aliases
= buffer
+ idx
;
240 ((char**) r_aliases
)[0] = r_alias
;
241 ((char**) r_aliases
)[1] = NULL
;
242 idx
+= 2*sizeof(char*);
244 ((char**) r_aliases
)[0] = NULL
;
245 idx
+= sizeof(char*);
248 /* Third, add addresses */
249 r_addr
= buffer
+ idx
;
253 for (a
= addresses
, n
= 0; n
< n_addresses
; a
++, n
++) {
257 memcpy(r_addr
+ i
*ALIGN(alen
), &a
->address
, alen
);
262 idx
+= c
*ALIGN(alen
);
264 } else if (af
== AF_INET
) {
265 *(uint32_t*) r_addr
= local_address_ipv4
;
267 } else if (socket_ipv6_is_enabled()) {
268 memcpy(r_addr
, LOCALADDRESS_IPV6
, 16);
272 /* Fourth, add address pointer array */
273 r_addr_list
= buffer
+ idx
;
277 for (i
= 0; i
< c
; i
++)
278 ((char**) r_addr_list
)[i
] = r_addr
+ i
*ALIGN(alen
);
280 ((char**) r_addr_list
)[i
] = NULL
;
281 idx
+= (c
+1) * sizeof(char*);
283 } else if (af
== AF_INET
|| socket_ipv6_is_enabled()) {
284 ((char**) r_addr_list
)[0] = r_addr
;
285 ((char**) r_addr_list
)[1] = NULL
;
286 idx
+= 2 * sizeof(char*);
288 ((char**) r_addr_list
)[0] = NULL
;
289 idx
+= sizeof(char*);
292 /* Verify the size matches */
295 result
->h_name
= r_name
;
296 result
->h_aliases
= (char**) r_aliases
;
297 result
->h_addrtype
= af
;
298 result
->h_length
= alen
;
299 result
->h_addr_list
= (char**) r_addr_list
;
307 /* Explicitly reset both *h_errnop and h_errno to work around
308 * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
309 *h_errnop
= NETDB_SUCCESS
;
312 return NSS_STATUS_SUCCESS
;
315 enum nss_status
_nss_myhostname_gethostbyname3_r(
318 struct hostent
*host
,
319 char *buffer
, size_t buflen
,
320 int *errnop
, int *h_errnop
,
324 _cleanup_free_
struct local_address
*addresses
= NULL
;
325 const char *canonical
, *additional
= NULL
;
326 _cleanup_free_
char *hn
= NULL
;
327 uint32_t local_address_ipv4
= 0;
331 BLOCK_SIGNALS(NSS_SIGNALS_BLOCK
);
342 if (!IN_SET(af
, AF_INET
, AF_INET6
)) {
344 *errnop
= EAFNOSUPPORT
;
346 return NSS_STATUS_UNAVAIL
;
349 if (af
== AF_INET6
&& !socket_ipv6_is_enabled())
352 if (is_localhost(name
)) {
354 canonical
= "localhost";
355 local_address_ipv4
= htobe32(INADDR_LOOPBACK
);
357 } else if (is_gateway_hostname(name
)) {
359 n_addresses
= local_gateways(NULL
, 0, af
, &addresses
);
360 if (n_addresses
<= 0)
363 canonical
= "_gateway";
365 } else if (is_outbound_hostname(name
)) {
367 n_addresses
= local_outbounds(NULL
, 0, af
, &addresses
);
368 if (n_addresses
<= 0)
371 canonical
= "_outbound";
374 hn
= gethostname_malloc();
378 *h_errnop
= NO_RECOVERY
;
379 return NSS_STATUS_TRYAGAIN
;
382 if (!streq(name
, hn
) && !streq_ptr(startswith(name
, hn
), "."))
385 n_addresses
= local_addresses(NULL
, 0, af
, &addresses
);
390 additional
= n_addresses
<= 0 && af
== AF_INET6
? "localhost" : NULL
;
391 local_address_ipv4
= LOCALADDRESS_IPV4
;
396 return fill_in_hostent(
397 canonical
, additional
,
399 addresses
, n_addresses
,
408 *h_errnop
= HOST_NOT_FOUND
;
409 return NSS_STATUS_NOTFOUND
;
412 enum nss_status
_nss_myhostname_gethostbyaddr2_r(
413 const void* addr
, socklen_t len
,
415 struct hostent
*host
,
416 char *buffer
, size_t buflen
,
417 int *errnop
, int *h_errnop
,
420 const char *canonical
= NULL
, *additional
= NULL
;
421 uint32_t local_address_ipv4
= LOCALADDRESS_IPV4
;
422 _cleanup_free_
struct local_address
*addresses
= NULL
;
423 _cleanup_free_
char *hn
= NULL
;
425 struct local_address
*a
;
426 bool additional_from_hostname
= false;
430 BLOCK_SIGNALS(NSS_SIGNALS_BLOCK
);
438 if (!IN_SET(af
, AF_INET
, AF_INET6
)) {
440 *errnop
= EAFNOSUPPORT
;
442 return NSS_STATUS_UNAVAIL
;
445 if (len
!= FAMILY_ADDRESS_SIZE(af
)) {
448 *h_errnop
= NO_RECOVERY
;
449 return NSS_STATUS_UNAVAIL
;
453 if ((*(uint32_t*) addr
) == LOCALADDRESS_IPV4
)
456 if ((*(uint32_t*) addr
) == htobe32(INADDR_LOOPBACK
)) {
457 canonical
= "localhost";
458 local_address_ipv4
= htobe32(INADDR_LOOPBACK
);
463 assert(af
== AF_INET6
);
465 if (!socket_ipv6_is_enabled())
468 if (memcmp(addr
, LOCALADDRESS_IPV6
, 16) == 0) {
469 canonical
= "localhost";
470 additional_from_hostname
= true;
475 n_addresses
= local_addresses(NULL
, 0, af
, &addresses
);
476 for (a
= addresses
, n
= 0; (int) n
< n_addresses
; n
++, a
++)
477 if (memcmp(addr
, &a
->address
, FAMILY_ADDRESS_SIZE(af
)) == 0)
480 addresses
= mfree(addresses
);
482 n_addresses
= local_gateways(NULL
, 0, af
, &addresses
);
483 for (a
= addresses
, n
= 0; (int) n
< n_addresses
; n
++, a
++)
484 if (memcmp(addr
, &a
->address
, FAMILY_ADDRESS_SIZE(af
)) == 0) {
485 canonical
= "_gateway";
490 *h_errnop
= HOST_NOT_FOUND
;
491 return NSS_STATUS_NOTFOUND
;
494 if (!canonical
|| additional_from_hostname
) {
495 hn
= gethostname_malloc();
499 *h_errnop
= NO_RECOVERY
;
500 return NSS_STATUS_TRYAGAIN
;
510 return fill_in_hostent(
511 canonical
, additional
,
513 addresses
, n_addresses
,
522 NSS_GETHOSTBYNAME_FALLBACKS(myhostname
);
523 NSS_GETHOSTBYADDR_FALLBACKS(myhostname
);