Update.

2004-09-15  Ulrich Drepper  <drepper@redhat.com>

	* nscd/Makefile (rountines): Add nscd_getai.
	(nscd-modules): Add aicache.
	* nscd/aicache.c: New file.
	* nscd/nscd_getai.c: New file.
	* nscd/cache.c (prune_cache): Handle GETAI request type.
	* nscd/connections.c: Add GETAI support in request handling.
	* nscd/nscd-client.h (request_type): Add GETAI.
	Define ai_response_header and struct nscd_ai_result types.
	(struct datahead): Add aidata field.
	Declare __nscd_getai.
	* nscd/nscd.c: Add getaddrinfo definition to catch problems.
	* nscd/nscd.h: Declare addhstai and readdhstai.

	* sysdeps/posix/getaddrinfo.c: Add support for using cached results.

	* nscd/nscd-client.h  (struct datahead): Use uint8_t instead of bool.

8 files changed, 654 insertions, 7 deletions

diff --git a/nscd/Makefile b/nscd/Makefile
index 7d0a9e38f1..a6a08a3ab8 100644
--- a/nscd/Makefile
+++ b/nscd/Makefile
@@ -21,7 +21,7 @@
 #
 subdir	:= nscd
 
-routines := nscd_getpw_r nscd_getgr_r nscd_gethst_r
+routines := nscd_getpw_r nscd_getgr_r nscd_gethst_r nscd_getai
 aux	:= nscd_helper
 
 include ../Makeconfig
@@ -32,7 +32,7 @@ vpath %.c ../locale/programs
 nscd-modules := nscd connections pwdcache getpwnam_r getpwuid_r grpcache \
 		getgrnam_r getgrgid_r hstcache gethstbyad_r gethstbynm2_r \
 		dbg_log nscd_conf nscd_stat cache mem nscd_setup_thread \
-		xmalloc xstrdup
+		xmalloc xstrdup aicache
 
 ifeq ($(have-thread-library),yes)
 
diff --git a/nscd/aicache.c b/nscd/aicache.c
new file mode 100644
index 0000000000..e7489065d4
--- /dev/null
+++ b/nscd/aicache.c
@@ -0,0 +1,428 @@
+/* Cache handling for host lookup.
+   Copyright (C) 2004 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <libintl.h>
+#include <netdb.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <dbg_log.h>
+#include <nscd.h>
+
+
+typedef enum nss_status (*nss_gethostbyname2_r)
+  (const char *name, int af, struct hostent *host,
+   char *buffer, size_t buflen, int *errnop,
+   int *h_errnop);
+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 void
+addhstaiX (struct database_dyn *db, int fd, request_header *req,
+	   void *key, uid_t uid, struct hashentry *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.  */
+  uid_t oldeuid = 0;
+
+  /* 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 (__builtin_expect (debug_level > 0, 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);
+    }
+
+  if (db->secure)
+    {
+      oldeuid = geteuid ();
+      seteuid (uid);
+    }
+
+  static service_user *hosts_database;
+  service_user *nip = NULL;
+  int no_more;
+  int rc6 = 0;
+  int rc4 = 0;
+  int herrno = 0;
+
+  if (hosts_database != NULL)
+    {
+      nip = hosts_database;
+      no_more = 0;
+    }
+  else
+    no_more = __nss_database_lookup ("hosts", NULL,
+				     "dns [!UNAVAIL=return] files", &nip);
+
+  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 = 512;
+  char *tmpbuf6 = alloca (tmpbuf6len);
+  size_t tmpbuf4len = 0;
+  char *tmpbuf4 = NULL;
+  char *canon = NULL;
+  ssize_t total = 0;
+  char *key_copy = NULL;
+  bool alloca_used = false;
+
+  while (!no_more)
+    {
+      nss_gethostbyname2_r fct = __nss_lookup_function (nip,
+							"gethostbyname2_r");
+      int status[2] = { NSS_STATUS_UNAVAIL, NSS_STATUS_UNAVAIL };
+
+      if (fct != NULL)
+	{
+ printf("fct=%p\n",fct);
+	  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));
+	      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 first.  */
+	  while (1)
+	    {
+	      rc4 = 0;
+	      status[1] = DL_CALL_FCT (fct, (key, AF_INET, &th[1], tmpbuf4,
+					     tmpbuf4len, &rc4, &herrno));
+	      if (rc4 != ERANGE || herrno != NETDB_INTERNAL)
+		break;
+	      tmpbuf4 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
+	    }
+
+	  if (rc4 != 0 || herrno == NETDB_INTERNAL)
+	    goto out;
+
+	  if (status[0] == NSS_STATUS_SUCCESS
+	      || status[1] == NSS_STATUS_SUCCESS)
+	    {
+	      /* We found the data.  Count the addresses and the size.  */
+	      int naddrs = 0;
+	      size_t addrslen = 0;
+	      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;
+		    }
+
+	      /* 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
+		{
+		  // XXX use gethostbyaddr
+		}
+	      size_t canonlen = canon == NULL ? 0 : (strlen (canon) + 1);
+
+	      total = sizeof (*dataset) + naddrs + addrslen + canonlen;
+
+	      /* Now we can allocate the data structure.  */
+	      if (he == NULL)
+		{
+		  dataset = (struct dataset *) mempool_alloc (db,
+							      total
+							      + req->key_len);
+		  if (dataset == NULL)
+		    ++db->head->addfailed;
+		}
+
+	      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;
+		}
+
+	      dataset->head.allocsize = total + req->key_len;
+	      dataset->head.recsize = total - offsetof (struct dataset, resp);
+	      dataset->head.notfound = false;
+	      dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
+	      dataset->head.usable = true;
+
+	      /* Compute the timeout time.  */
+	      dataset->head.timeout = time (NULL) + db->postimeout;
+
+	      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;
+
+	      char *addrs = (char *) (&dataset->resp + 1);
+	      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;
+		    }
+
+	      char *cp = family;
+	      if (canon != NULL)
+		cp = mempcpy (cp, canon, canonlen);
+
+	      key_copy = memcpy (cp, key, req->key_len);
+
+	      /* 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->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);
+		      if (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);
+
+		  TEMP_FAILURE_RETRY (write (fd, &dataset->resp, total));
+		}
+
+	      goto out;
+	    }
+
+	}
+
+      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;
+    }
+  else
+    {
+      /* We have no data.  This means we send the standard reply for
+	 this case.  */
+      total = sizeof (notfound);
+
+      if (fd != -1)
+	TEMP_FAILURE_RETRY (write (fd, &notfound, total));
+
+      dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len);
+      /* If we cannot permanently store the result, so be it.  */
+      if (dataset != NULL)
+	{
+	  dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
+	  dataset->head.recsize = total;
+	  dataset->head.notfound = true;
+	  dataset->head.nreloads = 0;
+	  dataset->head.usable = true;
+
+	  /* Compute the timeout time.  */
+	  dataset->head.timeout = time (NULL) + db->negtimeout;
+
+	  /* This is the reply.  */
+	  memcpy (&dataset->resp, &notfound, total);
+
+	  /* Copy the key data.  */
+	  key_copy = memcpy (dataset->strdata, key, req->key_len);
+	}
+      else
+	++db->head->addfailed;
+   }
+
+ out:
+  _res.options = old_res_options;
+
+  if (db->secure)
+    seteuid (oldeuid);
+
+  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);
+	}
+
+      /* Now get the lock to safely insert the records.  */
+      pthread_rwlock_rdlock (&db->lock);
+
+      if (cache_add (req->type, key_copy, req->key_len, &dataset->head, true,
+		     db, uid) < 0)
+	/* Ensure the data can be recovered.  */
+	dataset->head.usable = false;
+
+      pthread_rwlock_unlock (&db->lock);
+
+      /* Mark the old entry as obsolete.  */
+      if (dh != NULL)
+	dh->usable = false;
+    }
+}
+
+
+void
+addhstai (struct database_dyn *db, int fd, request_header *req, void *key,
+	  uid_t uid)
+{
+  addhstaiX (db, fd, req, key, uid, NULL, NULL);
+}
+
+
+void
+readdhstai (struct database_dyn *db, struct hashentry *he, struct datahead *dh)
+{
+  request_header req =
+    {
+      .type = GETAI,
+      .key_len = he->len
+    };
+
+  addhstaiX (db, -1, &req, db->data + he->key, he->owner, he, dh);
+}
diff --git a/nscd/cache.c b/nscd/cache.c
index 69c2efb4de..468b8d272a 100644
--- a/nscd/cache.c
+++ b/nscd/cache.c
@@ -313,6 +313,10 @@ prune_cache (struct database_dyn *table, time_t now)
 			  readdhstbyaddrv6 (table, runp, dh);
 			  break;
 
+			case GETAI:
+			  readdhstai (table, runp, dh);
+			  break;
+
 			default:
 			  assert (! "should never happen");
 			}
diff --git a/nscd/connections.c b/nscd/connections.c
index b95ab05b3a..fe33c76bcf 100644
--- a/nscd/connections.c
+++ b/nscd/connections.c
@@ -83,7 +83,8 @@ const char *serv2str[LASTREQ] =
   [INVALIDATE] = "INVALIDATE",
   [GETFDPW] = "GETFDPW",
   [GETFDGR] = "GETFDGR",
-  [GETFDHST] = "GETFDHST"
+  [GETFDHST] = "GETFDHST",
+  [GETAI] = "GETAI"
 };
 
 /* The control data structures for the services.  */
@@ -151,6 +152,7 @@ static struct database_dyn *const serv2db[LASTREQ] =
   [GETFDPW] = &dbs[pwddb],
   [GETFDGR] = &dbs[grpdb],
   [GETFDHST] = &dbs[hstdb],
+  [GETAI] = &dbs[hstdb],
 };
 
 
@@ -592,8 +594,9 @@ cannot handle old request version %d; current version is %d"),
 
   struct database_dyn *db = serv2db[req->type];
 
-  if (__builtin_expect (req->type, GETPWBYNAME) >= GETPWBYNAME
-      && __builtin_expect (req->type, LASTDBREQ) <= LASTDBREQ)
+  if ((__builtin_expect (req->type, GETPWBYNAME) >= GETPWBYNAME
+       && __builtin_expect (req->type, LASTDBREQ) <= LASTDBREQ)
+      || req->type == GETAI)
     {
       if (__builtin_expect (debug_level, 0) > 0)
 	{
@@ -702,6 +705,10 @@ cannot handle old request version %d; current version is %d"),
       addhstbyaddrv6 (db, fd, req, key, uid);
       break;
 
+    case GETAI:
+      addhstai (db, fd, req, key, uid);
+      break;
+
     case GETSTAT:
     case SHUTDOWN:
     case INVALIDATE:
diff --git a/nscd/nscd-client.h b/nscd/nscd-client.h
index 8f3f3a11d7..1a0dd732db 100644
--- a/nscd/nscd-client.h
+++ b/nscd/nscd-client.h
@@ -61,6 +61,7 @@ typedef enum
   GETFDPW,
   GETFDGR,
   GETFDHST,
+  GETAI,
   LASTREQ
 } request_type;
 
@@ -118,6 +119,28 @@ typedef struct
 } hst_response_header;
 
 
+/* Structure sent in reply to addrinfo query.  Note that this struct is
+   sent also if the service is disabled or there is no record found.  */
+typedef struct
+{
+  int32_t version;
+  int32_t found;
+  nscd_ssize_t naddrs;
+  nscd_ssize_t addrslen;
+  nscd_ssize_t canonlen;
+  int32_t error;
+} ai_response_header;
+
+/* Structure filled in by __nscd_getai.  */
+struct nscd_ai_result
+{
+  int naddrs;
+  char *canon;
+  uint8_t *family;
+  char *addrs;
+};
+
+
 /* Type for offsets in data part of database.  */
 typedef uint32_t ref_t;
 /* Value for invalid/no reference.  */
@@ -136,9 +159,9 @@ struct datahead
   nscd_ssize_t allocsize;	/* Allocated Bytes.  */
   nscd_ssize_t recsize;		/* Size of the record.  */
   nscd_time_t timeout;		/* Time when this entry becomes invalid.  */
-  bool notfound;		/* Nonzero if data has not been found.  */
+  uint8_t notfound;		/* Nonzero if data has not been found.  */
   uint8_t nreloads;		/* Reloads without use.  */
-  bool usable;			/* False if the entry must be ignored.  */
+  uint8_t usable;		/* False if the entry must be ignored.  */
   uint64_t :40;			/* Alignment.  */
 
   /* We need to have the following element aligned for the response
@@ -149,6 +172,7 @@ struct datahead
     pw_response_header pwdata;
     gr_response_header grdata;
     hst_response_header hstdata;
+    ai_response_header aidata;
     nscd_ssize_t align1;
     nscd_time_t align2;
   } data[0];
@@ -270,4 +294,8 @@ extern const struct datahead *__nscd_cache_search (request_type type,
 						   size_t keylen,
 						   const struct mapped_database *mapped);
 
+/* Look up in addrinfo cache.  */
+extern int __nscd_getai (const char *key, struct nscd_ai_result **result,
+			 int *h_errnop);
+
 #endif /* nscd.h */
diff --git a/nscd/nscd.c b/nscd/nscd.c
index 5c5c15598b..facea5ecdb 100644
--- a/nscd/nscd.c
+++ b/nscd/nscd.c
@@ -465,3 +465,14 @@ write_pid (const char *file)
 
   return 0;
 }
+
+
+/* This is an ugly hack which prevents getaddrinfo from being dragged
+   into nscd.  There currently is no special getaddrinfo version for
+   use in nscd.  In case it should be necessary such a version must be
+   created and this dummy version should be removed.  */
+void
+getaddrinfo (void)
+{
+  abort ();
+}
diff --git a/nscd/nscd.h b/nscd/nscd.h
index d32f5fed47..01c8ca11e0 100644
--- a/nscd/nscd.h
+++ b/nscd/nscd.h
@@ -193,6 +193,11 @@ extern void readdhstbynamev6 (struct database_dyn *db, struct hashentry *he,
 extern void readdhstbyaddrv6 (struct database_dyn *db, struct hashentry *he,
 			      struct datahead *dh);
 
+/* aicache.c */
+extern void addhstai (struct database_dyn *db, int fd, request_header *req,
+		      void *key, uid_t uid);
+extern void readdhstai (struct database_dyn *db, struct hashentry *he,
+			struct datahead *dh);
 
 /* mem.c */
 extern void *mempool_alloc (struct database_dyn *db, size_t len);
diff --git a/nscd/nscd_getai.c b/nscd/nscd_getai.c
new file mode 100644
index 0000000000..453f459425
--- /dev/null
+++ b/nscd/nscd_getai.c
@@ -0,0 +1,164 @@
+/* Copyright (C) 2004 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <netdb.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <not-cancel.h>
+
+#include "nscd-client.h"
+
+
+/* Define in nscd_gethst_r.c.  */
+extern int __nss_not_use_nscd_hosts;
+
+
+libc_locked_map_ptr (map_handle);
+/* Note that we only free the structure if necessary.  The memory
+   mapping is not removed since it is not visible to the malloc
+   handling.  */
+libc_freeres_fn (gr_map_free)
+{
+
+  if (map_handle.mapped != NO_MAPPING)
+    free (map_handle.mapped);
+}
+
+
+int
+__nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
+{
+  size_t keylen = strlen (key) + 1;
+  const ai_response_header *ai_resp = NULL;
+  struct nscd_ai_result *resultbuf = NULL;
+  const char *recend = (const char *) ~UINTMAX_C (0);
+  char *respdata = NULL;
+  int retval = -1;
+  int sock = -1;
+  int gc_cycle;
+
+  /* If the mapping is available, try to search there instead of
+     communicating with the nscd.  */
+  struct mapped_database *mapped = __nscd_get_map_ref (GETFDHST, "hosts",
+						       &map_handle, &gc_cycle);
+ retry:
+  if (mapped != MAP_FAILED)
+    {
+      const struct datahead *found = __nscd_cache_search (GETAI, key, keylen,
+							  mapped);
+      if (found != NULL)
+	{
+	  ai_resp = &found->data[0].aidata;
+	  respdata = (char *) (ai_resp + 1);
+	  recend = (const char *) found->data + found->recsize;
+	}
+    }
+
+  /* If we do not have the cache mapped, try to get the data over the
+     socket.  */
+  ai_response_header ai_resp_mem;
+  if (ai_resp == NULL)
+    {
+      sock = __nscd_open_socket (key, keylen, GETAI, &ai_resp_mem,
+				 sizeof (ai_resp_mem));
+      if (sock == -1)
+	{
+	  /* nscd not running or wrong version or hosts caching disabled.  */
+	  __nss_not_use_nscd_hosts = 1;
+	  goto out;;
+	}
+
+      ai_resp = &ai_resp_mem;
+    }
+
+  if (ai_resp->found == 1)
+    {
+      size_t datalen = ai_resp->naddrs + ai_resp->addrslen + ai_resp->canonlen;
+
+      /* This check is really only affects the case where the data
+	 comes from the mapped cache.  */
+      if ((char *) (ai_resp + 1) + datalen > recend)
+	{
+	  assert (sock == -1);
+	  goto out;
+	}
+
+      /* Create result.  */
+      resultbuf = (struct nscd_ai_result *) malloc (sizeof (*resultbuf)
+						    + datalen);
+      if (resultbuf == NULL)
+	{
+	  *h_errnop = NETDB_INTERNAL;
+	  return -1;
+	}
+
+      /* Set up the data structure, including pointers.  */
+      resultbuf->naddrs = ai_resp->naddrs;
+      resultbuf->addrs = (char *) (resultbuf + 1);
+      resultbuf->family = (uint8_t *) (resultbuf->addrs + ai_resp->addrslen);
+      if (ai_resp->canonlen != 0)
+	resultbuf->canon = (char *) (resultbuf->family + resultbuf->naddrs);
+      else
+	resultbuf->canon = NULL;
+
+      if (respdata == NULL)
+	{
+	  /* Read the data from the socket.  */
+	  if ((size_t) TEMP_FAILURE_RETRY (__read (sock, resultbuf + 1,
+						   datalen)) == datalen)
+	    {
+	      retval = 0;
+	      *result = resultbuf;
+	    }
+	}
+      else
+	{
+	  /* Copy the data in the block.  */
+	  memcpy (resultbuf + 1, respdata, datalen);
+
+	  retval = 0;
+	  *result = resultbuf;
+	}
+    }
+  else
+    {
+      /* Store the error number.  */
+      *h_errnop = ai_resp->error;
+
+      /* The `errno' to some value != ERANGE.  */
+      __set_errno (ENOENT);
+      /* Even though we have not found anything, the result is zero.  */
+      retval = 0;
+    }
+
+  if (sock != -1)
+    close_not_cancel_no_status (sock);
+ out:
+  if (__nscd_drop_map_ref (mapped, gc_cycle) != 0)
+    /* When we come here this means there has been a GC cycle while we
+       were looking for the data.  This means the data might have been
+       inconsistent.  Retry.  */
+    goto retry;
+
+  return retval;
+}