ap/libc/glibc/glibc-2.23/nscd/aicache.c - T106_DC - Gitiles

 /* Cache handling for host lookup.
    Copyright (C) 2004-2016 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/res_hconf.h>

 #include "dbg_log.h"
 #include "nscd.h"
 #ifdef HAVE_SENDFILE
 # include <kernel-features.h>
 #endif


 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 (__glibc_unlikely (!_res_hconf.initialized))
     _res_hconf_init ();
   if (__res_maybe_init (&_res, 0) == -1)
     no_more = 1;

   /* 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.  Currently this is decided by setting the
      RES_USE_INET6 bit in _res.options.  */
   int old_res_options = _res.options;
   _res.options &= ~RES_USE_INET6;

   size_t tmpbuf6len = 1024;
   char *tmpbuf6 = alloca (tmpbuf6len);
   size_t tmpbuf4len = 0;
   char *tmpbuf4 = NULL;
   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, tmpbuf6len,
 					      &rc6, &herrno, &ttl));
 	      if (rc6 != ERANGE || (herrno != NETDB_INTERNAL
 				    && herrno != TRY_AGAIN))
 		break;
 	      tmpbuf6 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
 	    }

 	  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,
 					     tmpbuf6len, &rc6, &herrno, &ttl,
 					     &canon));
 	      if (rc6 != ERANGE || herrno != NETDB_INTERNAL)
 		break;
 	      tmpbuf6 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
 	    }

 	  if (rc6 != 0 && herrno == NETDB_INTERNAL)
 	    goto out;

 	  /* If the IPv6 lookup has been successful do not use the
 	     buffer used in that lookup, use a new one.  */
 	  if (status[0] == NSS_STATUS_SUCCESS && rc6 == 0)
 	    {
 	      tmpbuf4len = 512;
 	      tmpbuf4 = alloca (tmpbuf4len);
 	    }
 	  else
 	    {
 	      tmpbuf4len = tmpbuf6len;
 	      tmpbuf4 = tmpbuf6;
 	    }

 	  /* Next collect IPv4 information.  */
 	  while (1)
 	    {
 	      rc4 = 0;
 	      status[1] = DL_CALL_FCT (fct, (key, AF_INET, &th[1], tmpbuf4,
 					     tmpbuf4len, &rc4, &herrno,
 					     ttl == INT32_MAX ? &ttl : NULL,
 					     canon == NULL ? &canon : NULL));
 	      if (rc4 != ERANGE || herrno != NETDB_INTERNAL)
 		break;
 	      tmpbuf4 = extend_alloca (tmpbuf4, tmpbuf4len, 2 * tmpbuf4len);
 	    }

 	  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)
 		{
 		  const size_t max_fqdn_len = 256;
 		  char *buf = alloca (max_fqdn_len);
 		  char *s;
 		  int rc;

 		  if (DL_CALL_FCT (cfct, (key, buf, max_fqdn_len, &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;
 		    }

 		  size_t tmpbuflen = 512;
 		  char *tmpbuf = alloca (tmpbuflen);
 		  int rc;
 		  while (1)
 		    {
 		      rc = __gethostbyaddr2_r (addr, addrlen, addrfamily,
 					       &hstent_mem, tmpbuf, tmpbuflen,
 					       &hstent, &herrno, NULL);
 		      if (rc != ERANGE || herrno != NETDB_INTERNAL)
 			break;
 		      tmpbuf = extend_alloca (tmpbuf, tmpbuflen,
 					      tmpbuflen * 2);
 		    }

 		  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);

 #ifdef HAVE_SENDFILE
 	  if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
 	    {
 	      assert (db->wr_fd != -1);
 	      assert ((char *) &dataset->resp > (char *) db->data);
 	      assert ((char *) dataset - (char *) db->head + total
 		      <= (sizeof (struct database_pers_head)
 			  + db->head->module * sizeof (ref_t)
 			  + db->head->data_size));
 # ifndef __ASSUME_SENDFILE
 	      ssize_t written;
 	      written =
 # endif
 		sendfileall (fd, db->wr_fd, (char *) &dataset->resp
 			     - (char *) db->head, dataset->head.recsize);
 # ifndef __ASSUME_SENDFILE
 	      if (written == -1 && errno == ENOSYS)
 		goto use_write;
 # endif
 	    }
 	  else
 # ifndef __ASSUME_SENDFILE
 	  use_write:
 # endif
 #endif
 	    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, &notfound, 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, &notfound, total);

 	  /* Copy the key data.  */
 	  key_copy = memcpy (dataset->strdata, key, req->key_len);
 	}
    }

  out:
   _res.options |= old_res_options & RES_USE_INET6;

   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;
     }

   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);
 }
	/* Cache handling for host lookup.
	Copyright (C) 2004-2016 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/res_hconf.h>

	#include "dbg_log.h"
	#include "nscd.h"
	#ifdef HAVE_SENDFILE
	# include <kernel-features.h>
	#endif


	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 (__glibc_unlikely (!_res_hconf.initialized))
	_res_hconf_init ();
	if (__res_maybe_init (&_res, 0) == -1)
	no_more = 1;

	/* 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. Currently this is decided by setting the
	RES_USE_INET6 bit in _res.options. */
	int old_res_options = _res.options;
	_res.options &= ~RES_USE_INET6;

	size_t tmpbuf6len = 1024;
	char *tmpbuf6 = alloca (tmpbuf6len);
	size_t tmpbuf4len = 0;
	char *tmpbuf4 = NULL;
	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, tmpbuf6len,
	&rc6, &herrno, &ttl));
	if (rc6 != ERANGE \|\| (herrno != NETDB_INTERNAL
	&& herrno != TRY_AGAIN))
	break;
	tmpbuf6 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
	}

	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,
	tmpbuf6len, &rc6, &herrno, &ttl,
	&canon));
	if (rc6 != ERANGE \|\| herrno != NETDB_INTERNAL)
	break;
	tmpbuf6 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
	}

	if (rc6 != 0 && herrno == NETDB_INTERNAL)
	goto out;

	/* If the IPv6 lookup has been successful do not use the
	buffer used in that lookup, use a new one. */
	if (status[0] == NSS_STATUS_SUCCESS && rc6 == 0)
	{
	tmpbuf4len = 512;
	tmpbuf4 = alloca (tmpbuf4len);
	}
	else
	{
	tmpbuf4len = tmpbuf6len;
	tmpbuf4 = tmpbuf6;
	}

	/* Next collect IPv4 information. */
	while (1)
	{
	rc4 = 0;
	status[1] = DL_CALL_FCT (fct, (key, AF_INET, &th[1], tmpbuf4,
	tmpbuf4len, &rc4, &herrno,
	ttl == INT32_MAX ? &ttl : NULL,
	canon == NULL ? &canon : NULL));
	if (rc4 != ERANGE \|\| herrno != NETDB_INTERNAL)
	break;
	tmpbuf4 = extend_alloca (tmpbuf4, tmpbuf4len, 2 * tmpbuf4len);
	}

	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)
	{
	const size_t max_fqdn_len = 256;
	char *buf = alloca (max_fqdn_len);
	char *s;
	int rc;

	if (DL_CALL_FCT (cfct, (key, buf, max_fqdn_len, &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;
	}

	size_t tmpbuflen = 512;
	char *tmpbuf = alloca (tmpbuflen);
	int rc;
	while (1)
	{
	rc = __gethostbyaddr2_r (addr, addrlen, addrfamily,
	&hstent_mem, tmpbuf, tmpbuflen,
	&hstent, &herrno, NULL);
	if (rc != ERANGE \|\| herrno != NETDB_INTERNAL)
	break;
	tmpbuf = extend_alloca (tmpbuf, tmpbuflen,
	tmpbuflen * 2);
	}

	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);

	#ifdef HAVE_SENDFILE
	if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
	{
	assert (db->wr_fd != -1);
	assert ((char ) &dataset->resp > (char ) db->data);
	assert ((char ) dataset - (char ) db->head + total
	<= (sizeof (struct database_pers_head)
	+ db->head->module * sizeof (ref_t)
	+ db->head->data_size));
	# ifndef __ASSUME_SENDFILE
	ssize_t written;
	written =
	# endif
	sendfileall (fd, db->wr_fd, (char *) &dataset->resp
	- (char *) db->head, dataset->head.recsize);
	# ifndef __ASSUME_SENDFILE
	if (written == -1 && errno == ENOSYS)
	goto use_write;
	# endif
	}
	else
	# ifndef __ASSUME_SENDFILE
	use_write:
	# endif
	#endif
	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, &notfound, 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, &notfound, total);

	/* Copy the key data. */
	key_copy = memcpy (dataset->strdata, key, req->key_len);
	}
	}

	out:
	_res.options \|= old_res_options & RES_USE_INET6;

	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;
	}

	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);
	}