1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567
|
/* Cache handling for host lookup.
Copyright (C) 2004-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
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 of the License, or
(at your option) any later version.
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/>. */
#include <assert.h>
#include <errno.h>
#include <libintl.h>
#include <netdb.h>
#include <nss.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/mman.h>
#include <resolv/resolv-internal.h>
#include <resolv/resolv_context.h>
#include <resolv/res_use_inet6.h>
#include <scratch_buffer.h>
#include "dbg_log.h"
#include "nscd.h"
typedef enum nss_status (*nss_gethostbyname4_r)
(const char *name, struct gaih_addrtuple **pat,
char *buffer, size_t buflen, int *errnop,
int *h_errnop, int32_t *ttlp);
typedef enum nss_status (*nss_gethostbyname3_r)
(const char *name, int af, struct hostent *host,
char *buffer, size_t buflen, int *errnop,
int *h_errnop, int32_t *, char **);
typedef enum nss_status (*nss_getcanonname_r)
(const char *name, char *buffer, size_t buflen, char **result,
int *errnop, int *h_errnop);
static const ai_response_header notfound =
{
.version = NSCD_VERSION,
.found = 0,
.naddrs = 0,
.addrslen = 0,
.canonlen = 0,
.error = 0
};
static time_t
addhstaiX (struct database_dyn *db, int fd, request_header *req,
void *key, uid_t uid, struct hashentry *const he,
struct datahead *dh)
{
/* Search for the entry matching the key. Please note that we don't
look again in the table whether the dataset is now available. We
simply insert it. It does not matter if it is in there twice. The
pruning function only will look at the timestamp. */
/* We allocate all data in one memory block: the iov vector,
the response header and the dataset itself. */
struct dataset
{
struct datahead head;
ai_response_header resp;
char strdata[0];
} *dataset = NULL;
if (__glibc_unlikely (debug_level > 0))
{
if (he == NULL)
dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) key);
else
dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) key);
}
static service_user *hosts_database;
service_user *nip;
int no_more;
int rc6 = 0;
int rc4 = 0;
int herrno = 0;
if (hosts_database == NULL)
no_more = __nss_database_lookup ("hosts", NULL,
"dns [!UNAVAIL=return] files",
&hosts_database);
else
no_more = 0;
nip = hosts_database;
/* Initialize configurations. If we are looking for both IPv4 and
IPv6 address we don't want the lookup functions to automatically
promote IPv4 addresses to IPv6 addresses. Therefore, use the
_no_inet6 variant. */
struct resolv_context *ctx = __resolv_context_get ();
bool enable_inet6 = __resolv_context_disable_inet6 (ctx);
if (ctx == NULL)
no_more = 1;
struct scratch_buffer tmpbuf6;
scratch_buffer_init (&tmpbuf6);
struct scratch_buffer tmpbuf4;
scratch_buffer_init (&tmpbuf4);
struct scratch_buffer canonbuf;
scratch_buffer_init (&canonbuf);
int32_t ttl = INT32_MAX;
ssize_t total = 0;
char *key_copy = NULL;
bool alloca_used = false;
time_t timeout = MAX_TIMEOUT_VALUE;
while (!no_more)
{
void *cp;
int status[2] = { NSS_STATUS_UNAVAIL, NSS_STATUS_UNAVAIL };
int naddrs = 0;
size_t addrslen = 0;
char *canon = NULL;
size_t canonlen;
nss_gethostbyname4_r fct4 = __nss_lookup_function (nip,
"gethostbyname4_r");
if (fct4 != NULL)
{
struct gaih_addrtuple atmem;
struct gaih_addrtuple *at;
while (1)
{
at = &atmem;
rc6 = 0;
herrno = 0;
status[1] = DL_CALL_FCT (fct4, (key, &at,
tmpbuf6.data, tmpbuf6.length,
&rc6, &herrno, &ttl));
if (rc6 != ERANGE || (herrno != NETDB_INTERNAL
&& herrno != TRY_AGAIN))
break;
if (!scratch_buffer_grow (&tmpbuf6))
{
rc6 = ENOMEM;
break;
}
}
if (rc6 != 0 && herrno == NETDB_INTERNAL)
goto out;
if (status[1] != NSS_STATUS_SUCCESS)
goto next_nip;
/* We found the data. Count the addresses and the size. */
for (const struct gaih_addrtuple *at2 = at = &atmem; at2 != NULL;
at2 = at2->next)
{
++naddrs;
/* We do not handle anything other than IPv4 and IPv6
addresses. The getaddrinfo implementation does not
either so it is not worth trying to do more. */
if (at2->family == AF_INET)
addrslen += INADDRSZ;
else if (at2->family == AF_INET6)
addrslen += IN6ADDRSZ;
}
canon = at->name;
canonlen = strlen (canon) + 1;
total = sizeof (*dataset) + naddrs + addrslen + canonlen;
/* Now we can allocate the data structure. If the TTL of the
entry is reported as zero do not cache the entry at all. */
if (ttl != 0 && he == NULL)
dataset = (struct dataset *) mempool_alloc (db, total
+ req->key_len, 1);
if (dataset == NULL)
{
/* We cannot permanently add the result in the moment. But
we can provide the result as is. Store the data in some
temporary memory. */
dataset = (struct dataset *) alloca (total + req->key_len);
/* We cannot add this record to the permanent database. */
alloca_used = true;
}
/* Fill in the address and address families. */
char *addrs = dataset->strdata;
uint8_t *family = (uint8_t *) (addrs + addrslen);
for (const struct gaih_addrtuple *at2 = at; at2 != NULL;
at2 = at2->next)
{
*family++ = at2->family;
if (at2->family == AF_INET)
addrs = mempcpy (addrs, at2->addr, INADDRSZ);
else if (at2->family == AF_INET6)
addrs = mempcpy (addrs, at2->addr, IN6ADDRSZ);
}
cp = family;
}
else
{
/* Prefer the function which also returns the TTL and
canonical name. */
nss_gethostbyname3_r fct = __nss_lookup_function (nip,
"gethostbyname3_r");
if (fct == NULL)
fct = __nss_lookup_function (nip, "gethostbyname2_r");
if (fct == NULL)
goto next_nip;
struct hostent th[2];
/* Collect IPv6 information first. */
while (1)
{
rc6 = 0;
status[0] = DL_CALL_FCT (fct, (key, AF_INET6, &th[0],
tmpbuf6.data, tmpbuf6.length,
&rc6, &herrno, &ttl,
&canon));
if (rc6 != ERANGE || herrno != NETDB_INTERNAL)
break;
if (!scratch_buffer_grow (&tmpbuf6))
{
rc6 = ENOMEM;
break;
}
}
if (rc6 != 0 && herrno == NETDB_INTERNAL)
goto out;
/* Next collect IPv4 information. */
while (1)
{
rc4 = 0;
status[1] = DL_CALL_FCT (fct, (key, AF_INET, &th[1],
tmpbuf4.data, tmpbuf4.length,
&rc4, &herrno,
ttl == INT32_MAX ? &ttl : NULL,
canon == NULL ? &canon : NULL));
if (rc4 != ERANGE || herrno != NETDB_INTERNAL)
break;
if (!scratch_buffer_grow (&tmpbuf4))
{
rc4 = ENOMEM;
break;
}
}
if (rc4 != 0 && herrno == NETDB_INTERNAL)
goto out;
if (status[0] != NSS_STATUS_SUCCESS
&& status[1] != NSS_STATUS_SUCCESS)
goto next_nip;
/* We found the data. Count the addresses and the size. */
for (int j = 0; j < 2; ++j)
if (status[j] == NSS_STATUS_SUCCESS)
for (int i = 0; th[j].h_addr_list[i] != NULL; ++i)
{
++naddrs;
addrslen += th[j].h_length;
}
if (canon == NULL)
{
/* Determine the canonical name. */
nss_getcanonname_r cfct;
cfct = __nss_lookup_function (nip, "getcanonname_r");
if (cfct != NULL)
{
char *s;
int rc;
if (DL_CALL_FCT (cfct, (key, canonbuf.data, canonbuf.length,
&s, &rc, &herrno))
== NSS_STATUS_SUCCESS)
canon = s;
else
/* Set to name now to avoid using gethostbyaddr. */
canon = key;
}
else
{
struct hostent *hstent = NULL;
int herrno;
struct hostent hstent_mem;
void *addr;
size_t addrlen;
int addrfamily;
if (status[1] == NSS_STATUS_SUCCESS)
{
addr = th[1].h_addr_list[0];
addrlen = sizeof (struct in_addr);
addrfamily = AF_INET;
}
else
{
addr = th[0].h_addr_list[0];
addrlen = sizeof (struct in6_addr);
addrfamily = AF_INET6;
}
int rc;
while (1)
{
rc = __gethostbyaddr2_r (addr, addrlen, addrfamily,
&hstent_mem,
canonbuf.data, canonbuf.length,
&hstent, &herrno, NULL);
if (rc != ERANGE || herrno != NETDB_INTERNAL)
break;
if (!scratch_buffer_grow (&canonbuf))
{
rc = ENOMEM;
break;
}
}
if (rc == 0)
{
if (hstent != NULL)
canon = hstent->h_name;
else
canon = key;
}
}
}
canonlen = canon == NULL ? 0 : (strlen (canon) + 1);
total = sizeof (*dataset) + naddrs + addrslen + canonlen;
/* Now we can allocate the data structure. If the TTL of the
entry is reported as zero do not cache the entry at all. */
if (ttl != 0 && he == NULL)
dataset = (struct dataset *) mempool_alloc (db, total
+ req->key_len, 1);
if (dataset == NULL)
{
/* We cannot permanently add the result in the moment. But
we can provide the result as is. Store the data in some
temporary memory. */
dataset = (struct dataset *) alloca (total + req->key_len);
/* We cannot add this record to the permanent database. */
alloca_used = true;
}
/* Fill in the address and address families. */
char *addrs = dataset->strdata;
uint8_t *family = (uint8_t *) (addrs + addrslen);
for (int j = 0; j < 2; ++j)
if (status[j] == NSS_STATUS_SUCCESS)
for (int i = 0; th[j].h_addr_list[i] != NULL; ++i)
{
addrs = mempcpy (addrs, th[j].h_addr_list[i],
th[j].h_length);
*family++ = th[j].h_addrtype;
}
cp = family;
}
timeout = datahead_init_pos (&dataset->head, total + req->key_len,
total - offsetof (struct dataset, resp),
he == NULL ? 0 : dh->nreloads + 1,
ttl == INT32_MAX ? db->postimeout : ttl);
/* Fill in the rest of the dataset. */
dataset->resp.version = NSCD_VERSION;
dataset->resp.found = 1;
dataset->resp.naddrs = naddrs;
dataset->resp.addrslen = addrslen;
dataset->resp.canonlen = canonlen;
dataset->resp.error = NETDB_SUCCESS;
if (canon != NULL)
cp = mempcpy (cp, canon, canonlen);
key_copy = memcpy (cp, key, req->key_len);
assert (cp == (char *) dataset + total);
/* Now we can determine whether on refill we have to create a
new record or not. */
if (he != NULL)
{
assert (fd == -1);
if (total + req->key_len == dh->allocsize
&& total - offsetof (struct dataset, resp) == dh->recsize
&& memcmp (&dataset->resp, dh->data,
dh->allocsize - offsetof (struct dataset,
resp)) == 0)
{
/* The data has not changed. We will just bump the
timeout value. Note that the new record has been
allocated on the stack and need not be freed. */
dh->timeout = dataset->head.timeout;
dh->ttl = dataset->head.ttl;
++dh->nreloads;
}
else
{
/* We have to create a new record. Just allocate
appropriate memory and copy it. */
struct dataset *newp
= (struct dataset *) mempool_alloc (db, total + req->key_len,
1);
if (__glibc_likely (newp != NULL))
{
/* Adjust pointer into the memory block. */
key_copy = (char *) newp + (key_copy - (char *) dataset);
dataset = memcpy (newp, dataset, total + req->key_len);
alloca_used = false;
}
/* Mark the old record as obsolete. */
dh->usable = false;
}
}
else
{
/* We write the dataset before inserting it to the database
since while inserting this thread might block and so
would unnecessarily let the receiver wait. */
assert (fd != -1);
writeall (fd, &dataset->resp, dataset->head.recsize);
}
goto out;
next_nip:
if (nss_next_action (nip, status[1]) == NSS_ACTION_RETURN)
break;
if (nip->next == NULL)
no_more = -1;
else
nip = nip->next;
}
/* No result found. Create a negative result record. */
if (he != NULL && rc4 == EAGAIN)
{
/* If we have an old record available but cannot find one now
because the service is not available we keep the old record
and make sure it does not get removed. */
if (reload_count != UINT_MAX && dh->nreloads == reload_count)
/* Do not reset the value if we never not reload the record. */
dh->nreloads = reload_count - 1;
/* Reload with the same time-to-live value. */
timeout = dh->timeout = time (NULL) + dh->ttl;
}
else
{
/* We have no data. This means we send the standard reply for
this case. */
total = sizeof (notfound);
if (fd != -1)
TEMP_FAILURE_RETRY (send (fd, ¬found, total, MSG_NOSIGNAL));
/* If we have a transient error or cannot permanently store the
result, so be it. */
if (rc4 == EAGAIN || __builtin_expect (db->negtimeout == 0, 0))
{
/* Mark the old entry as obsolete. */
if (dh != NULL)
dh->usable = false;
dataset = NULL;
}
else if ((dataset = mempool_alloc (db, (sizeof (struct dataset)
+ req->key_len), 1)) != NULL)
{
timeout = datahead_init_neg (&dataset->head,
sizeof (struct dataset) + req->key_len,
total, db->negtimeout);
/* This is the reply. */
memcpy (&dataset->resp, ¬found, total);
/* Copy the key data. */
key_copy = memcpy (dataset->strdata, key, req->key_len);
}
}
out:
__resolv_context_enable_inet6 (ctx, enable_inet6);
__resolv_context_put (ctx);
if (dataset != NULL && !alloca_used)
{
/* If necessary, we also propagate the data to disk. */
if (db->persistent)
{
// XXX async OK?
uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
msync ((void *) pval,
((uintptr_t) dataset & pagesize_m1) + total + req->key_len,
MS_ASYNC);
}
(void) cache_add (req->type, key_copy, req->key_len, &dataset->head,
true, db, uid, he == NULL);
pthread_rwlock_unlock (&db->lock);
/* Mark the old entry as obsolete. */
if (dh != NULL)
dh->usable = false;
}
scratch_buffer_free (&tmpbuf6);
scratch_buffer_free (&tmpbuf4);
scratch_buffer_free (&canonbuf);
return timeout;
}
void
addhstai (struct database_dyn *db, int fd, request_header *req, void *key,
uid_t uid)
{
addhstaiX (db, fd, req, key, uid, NULL, NULL);
}
time_t
readdhstai (struct database_dyn *db, struct hashentry *he, struct datahead *dh)
{
request_header req =
{
.type = GETAI,
.key_len = he->len
};
return addhstaiX (db, -1, &req, db->data + he->key, he->owner, he, dh);
}
|