1 /* Cache handling for host lookup.
2 Copyright (C) 2004-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published
8 by the Free Software Foundation; version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, see <https://www.gnu.org/licenses/>. */
28 #include <resolv/resolv-internal.h>
29 #include <resolv/resolv_context.h>
30 #include <scratch_buffer.h>
36 static const ai_response_header notfound
=
38 .version
= NSCD_VERSION
,
48 addhstaiX (struct database_dyn
*db
, int fd
, request_header
*req
,
49 void *key
, uid_t uid
, struct hashentry
*const he
,
52 /* Search for the entry matching the key. Please note that we don't
53 look again in the table whether the dataset is now available. We
54 simply insert it. It does not matter if it is in there twice. The
55 pruning function only will look at the timestamp. */
57 /* We allocate all data in one memory block: the iov vector,
58 the response header and the dataset itself. */
62 ai_response_header resp
;
66 if (__glibc_unlikely (debug_level
> 0))
69 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) key
);
71 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) key
);
80 no_more
= !__nss_database_get (nss_database_hosts
, &nip
);
82 /* Initialize configurations. */
83 struct resolv_context
*ctx
= __resolv_context_get ();
87 struct scratch_buffer tmpbuf6
;
88 scratch_buffer_init (&tmpbuf6
);
89 struct scratch_buffer tmpbuf4
;
90 scratch_buffer_init (&tmpbuf4
);
91 struct scratch_buffer canonbuf
;
92 scratch_buffer_init (&canonbuf
);
94 int32_t ttl
= INT32_MAX
;
96 char *key_copy
= NULL
;
97 bool alloca_used
= false;
98 time_t timeout
= MAX_TIMEOUT_VALUE
;
103 int status
[2] = { NSS_STATUS_UNAVAIL
, NSS_STATUS_UNAVAIL
};
110 nss_gethostbyname4_r
*fct4
= __nss_lookup_function (nip
,
114 struct gaih_addrtuple atmem
;
115 struct gaih_addrtuple
*at
;
121 status
[1] = DL_CALL_FCT (fct4
, (key
, &at
,
122 tmpbuf6
.data
, tmpbuf6
.length
,
123 &rc6
, &herrno
, &ttl
));
124 if (rc6
!= ERANGE
|| (herrno
!= NETDB_INTERNAL
125 && herrno
!= TRY_AGAIN
))
127 if (!scratch_buffer_grow (&tmpbuf6
))
134 if (rc6
!= 0 && herrno
== NETDB_INTERNAL
)
137 if (status
[1] != NSS_STATUS_SUCCESS
)
140 /* We found the data. Count the addresses and the size. */
141 for (const struct gaih_addrtuple
*at2
= at
= &atmem
; at2
!= NULL
;
145 /* We do not handle anything other than IPv4 and IPv6
146 addresses. The getaddrinfo implementation does not
147 either so it is not worth trying to do more. */
148 if (at2
->family
== AF_INET
)
149 addrslen
+= INADDRSZ
;
150 else if (at2
->family
== AF_INET6
)
151 addrslen
+= IN6ADDRSZ
;
154 canonlen
= strlen (canon
) + 1;
156 total
= sizeof (*dataset
) + naddrs
+ addrslen
+ canonlen
;
158 /* Now we can allocate the data structure. If the TTL of the
159 entry is reported as zero do not cache the entry at all. */
160 if (ttl
!= 0 && he
== NULL
)
161 dataset
= (struct dataset
*) mempool_alloc (db
, total
166 /* We cannot permanently add the result in the moment. But
167 we can provide the result as is. Store the data in some
169 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
171 /* We cannot add this record to the permanent database. */
175 /* Fill in the address and address families. */
176 char *addrs
= dataset
->strdata
;
177 uint8_t *family
= (uint8_t *) (addrs
+ addrslen
);
179 for (const struct gaih_addrtuple
*at2
= at
; at2
!= NULL
;
182 *family
++ = at2
->family
;
183 if (at2
->family
== AF_INET
)
184 addrs
= mempcpy (addrs
, at2
->addr
, INADDRSZ
);
185 else if (at2
->family
== AF_INET6
)
186 addrs
= mempcpy (addrs
, at2
->addr
, IN6ADDRSZ
);
193 /* Prefer the function which also returns the TTL and
195 nss_gethostbyname3_r
*fct
196 = __nss_lookup_function (nip
, "gethostbyname3_r");
198 fct
= __nss_lookup_function (nip
, "gethostbyname2_r");
203 struct hostent th
[2];
205 /* Collect IPv6 information first. */
209 status
[0] = DL_CALL_FCT (fct
, (key
, AF_INET6
, &th
[0],
210 tmpbuf6
.data
, tmpbuf6
.length
,
213 if (rc6
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
215 if (!scratch_buffer_grow (&tmpbuf6
))
222 if (rc6
!= 0 && herrno
== NETDB_INTERNAL
)
225 /* Next collect IPv4 information. */
229 status
[1] = DL_CALL_FCT (fct
, (key
, AF_INET
, &th
[1],
230 tmpbuf4
.data
, tmpbuf4
.length
,
232 ttl
== INT32_MAX
? &ttl
: NULL
,
233 canon
== NULL
? &canon
: NULL
));
234 if (rc4
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
236 if (!scratch_buffer_grow (&tmpbuf4
))
243 if (rc4
!= 0 && herrno
== NETDB_INTERNAL
)
246 if (status
[0] != NSS_STATUS_SUCCESS
247 && status
[1] != NSS_STATUS_SUCCESS
)
250 /* We found the data. Count the addresses and the size. */
251 for (int j
= 0; j
< 2; ++j
)
252 if (status
[j
] == NSS_STATUS_SUCCESS
)
253 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
256 addrslen
+= th
[j
].h_length
;
261 /* Determine the canonical name. */
262 nss_getcanonname_r
*cfct
;
263 cfct
= __nss_lookup_function (nip
, "getcanonname_r");
269 if (DL_CALL_FCT (cfct
, (key
, canonbuf
.data
, canonbuf
.length
,
271 == NSS_STATUS_SUCCESS
)
274 /* Set to name now to avoid using gethostbyaddr. */
279 struct hostent
*hstent
= NULL
;
281 struct hostent hstent_mem
;
286 if (status
[1] == NSS_STATUS_SUCCESS
)
288 addr
= th
[1].h_addr_list
[0];
289 addrlen
= sizeof (struct in_addr
);
290 addrfamily
= AF_INET
;
294 addr
= th
[0].h_addr_list
[0];
295 addrlen
= sizeof (struct in6_addr
);
296 addrfamily
= AF_INET6
;
302 rc
= __gethostbyaddr2_r (addr
, addrlen
, addrfamily
,
304 canonbuf
.data
, canonbuf
.length
,
305 &hstent
, &herrno
, NULL
);
306 if (rc
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
308 if (!scratch_buffer_grow (&canonbuf
))
318 canon
= hstent
->h_name
;
325 canonlen
= canon
== NULL
? 0 : (strlen (canon
) + 1);
327 total
= sizeof (*dataset
) + naddrs
+ addrslen
+ canonlen
;
330 /* Now we can allocate the data structure. If the TTL of the
331 entry is reported as zero do not cache the entry at all. */
332 if (ttl
!= 0 && he
== NULL
)
333 dataset
= (struct dataset
*) mempool_alloc (db
, total
338 /* We cannot permanently add the result in the moment. But
339 we can provide the result as is. Store the data in some
341 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
343 /* We cannot add this record to the permanent database. */
347 /* Fill in the address and address families. */
348 char *addrs
= dataset
->strdata
;
349 uint8_t *family
= (uint8_t *) (addrs
+ addrslen
);
351 for (int j
= 0; j
< 2; ++j
)
352 if (status
[j
] == NSS_STATUS_SUCCESS
)
353 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
355 addrs
= mempcpy (addrs
, th
[j
].h_addr_list
[i
],
357 *family
++ = th
[j
].h_addrtype
;
363 timeout
= datahead_init_pos (&dataset
->head
, total
+ req
->key_len
,
364 total
- offsetof (struct dataset
, resp
),
365 he
== NULL
? 0 : dh
->nreloads
+ 1,
366 ttl
== INT32_MAX
? db
->postimeout
: ttl
);
368 /* Fill in the rest of the dataset. */
369 dataset
->resp
.version
= NSCD_VERSION
;
370 dataset
->resp
.found
= 1;
371 dataset
->resp
.naddrs
= naddrs
;
372 dataset
->resp
.addrslen
= addrslen
;
373 dataset
->resp
.canonlen
= canonlen
;
374 dataset
->resp
.error
= NETDB_SUCCESS
;
377 cp
= mempcpy (cp
, canon
, canonlen
);
379 key_copy
= memcpy (cp
, key
, req
->key_len
);
381 assert (cp
== (char *) dataset
+ total
);
383 /* Now we can determine whether on refill we have to create a
384 new record or not. */
389 if (total
+ req
->key_len
== dh
->allocsize
390 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
391 && memcmp (&dataset
->resp
, dh
->data
,
392 dh
->allocsize
- offsetof (struct dataset
,
395 /* The data has not changed. We will just bump the
396 timeout value. Note that the new record has been
397 allocated on the stack and need not be freed. */
398 dh
->timeout
= dataset
->head
.timeout
;
399 dh
->ttl
= dataset
->head
.ttl
;
404 /* We have to create a new record. Just allocate
405 appropriate memory and copy it. */
407 = (struct dataset
*) mempool_alloc (db
, total
+ req
->key_len
,
409 if (__glibc_likely (newp
!= NULL
))
411 /* Adjust pointer into the memory block. */
412 key_copy
= (char *) newp
+ (key_copy
- (char *) dataset
);
414 dataset
= memcpy (newp
, dataset
, total
+ req
->key_len
);
418 /* Mark the old record as obsolete. */
424 /* We write the dataset before inserting it to the database
425 since while inserting this thread might block and so
426 would unnecessarily let the receiver wait. */
429 writeall (fd
, &dataset
->resp
, dataset
->head
.recsize
);
435 if (nss_next_action (nip
, status
[1]) == NSS_ACTION_RETURN
)
438 if (nip
[1].module
== NULL
)
444 /* No result found. Create a negative result record. */
445 if (he
!= NULL
&& rc4
== EAGAIN
)
447 /* If we have an old record available but cannot find one now
448 because the service is not available we keep the old record
449 and make sure it does not get removed. */
450 if (reload_count
!= UINT_MAX
&& dh
->nreloads
== reload_count
)
451 /* Do not reset the value if we never not reload the record. */
452 dh
->nreloads
= reload_count
- 1;
454 /* Reload with the same time-to-live value. */
455 timeout
= dh
->timeout
= time (NULL
) + dh
->ttl
;
459 /* We have no data. This means we send the standard reply for
461 total
= sizeof (notfound
);
464 TEMP_FAILURE_RETRY (send (fd
, ¬found
, total
, MSG_NOSIGNAL
));
466 /* If we have a transient error or cannot permanently store the
468 if (rc4
== EAGAIN
|| __builtin_expect (db
->negtimeout
== 0, 0))
470 /* Mark the old entry as obsolete. */
475 else if ((dataset
= mempool_alloc (db
, (sizeof (struct dataset
)
476 + req
->key_len
), 1)) != NULL
)
478 timeout
= datahead_init_neg (&dataset
->head
,
479 sizeof (struct dataset
) + req
->key_len
,
480 total
, db
->negtimeout
);
482 /* This is the reply. */
483 memcpy (&dataset
->resp
, ¬found
, total
);
485 /* Copy the key data. */
486 key_copy
= memcpy (dataset
->strdata
, key
, req
->key_len
);
491 __resolv_context_put (ctx
);
493 if (dataset
!= NULL
&& !alloca_used
)
495 /* If necessary, we also propagate the data to disk. */
499 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
500 msync ((void *) pval
,
501 ((uintptr_t) dataset
& pagesize_m1
) + total
+ req
->key_len
,
505 (void) cache_add (req
->type
, key_copy
, req
->key_len
, &dataset
->head
,
506 true, db
, uid
, he
== NULL
);
508 pthread_rwlock_unlock (&db
->lock
);
510 /* Mark the old entry as obsolete. */
515 scratch_buffer_free (&tmpbuf6
);
516 scratch_buffer_free (&tmpbuf4
);
517 scratch_buffer_free (&canonbuf
);
524 addhstai (struct database_dyn
*db
, int fd
, request_header
*req
, void *key
,
527 addhstaiX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
532 readdhstai (struct database_dyn
*db
, struct hashentry
*he
, struct datahead
*dh
)
540 return addhstaiX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);