/* 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.

   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, see

   <http://www.gnu.org/licenses/>.  */

#include <assert.h>

#include <errno.h>

#include <netdb.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <not-cancel.h>

#include "nscd-client.h"

#include "nscd_proto.h"

/* Define in nscd_gethst_r.c.  */

extern int __nss_not_use_nscd_hosts;

/* We use the mapping from nscd_gethst.  */

libc_locked_map_ptr (extern, __hst_map_handle) attribute_hidden;

/* Defined in nscd_gethst_r.c.  */

extern int __nss_have_localdomain attribute_hidden;

int

__nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)

{

  if (__glibc_unlikely (__nss_have_localdomain >= 0))

    {

      if (__nss_have_localdomain == 0)

	__nss_have_localdomain = getenv ("LOCALDOMAIN") != NULL ? 1 : -1;

      if (__nss_have_localdomain > 0)

	{

	  __nss_not_use_nscd_hosts = 1;

	  return -1;

	}

    }

  size_t keylen = strlen (key) + 1;

  int gc_cycle;

  int nretries = 0;

  /* If the mapping is available, try to search there instead of

     communicating with the nscd.  */

  struct mapped_database *mapped;

  mapped = __nscd_get_map_ref (GETFDHST, "hosts", &__hst_map_handle,

			       &gc_cycle);

 retry:;

  struct nscd_ai_result *resultbuf = NULL;

  const char *recend = (const char *) ~UINTMAX_C (0);

  char *respdata = NULL;

  int retval = -1;

  int sock = -1;

  ai_response_header ai_resp;

  if (mapped != NO_MAPPING)

    {

      struct datahead *found = __nscd_cache_search (GETAI, key, keylen,

						    mapped, sizeof ai_resp);

      if (found != NULL)

	{

	  respdata = (char *) (&found->data[0].aidata + 1);

	  ai_resp = found->data[0].aidata;

	  recend = (const char *) found->data + found->recsize;

	  /* Now check if we can trust ai_resp fields.  If GC is

	     in progress, it can contain anything.  */

	  if (mapped->head->gc_cycle != gc_cycle)

	    {

	      retval = -2;

	      goto out;

	    }

	}

    }

  /* If we do not have the cache mapped, try to get the data over the

     socket.  */

  if (respdata == NULL)

    {

      sock = __nscd_open_socket (key, keylen, GETAI, &ai_resp,

				 sizeof (ai_resp));

      if (sock == -1)

	{

	  /* nscd not running or wrong version.  */

	  __nss_not_use_nscd_hosts = 1;

	  goto out;

	}

    }

  if (ai_resp.found == 1)

    {

      size_t datalen = ai_resp.naddrs + ai_resp.addrslen + ai_resp.canonlen;

      /* This check really only affects the case where the data

	 comes from the mapped cache.  */

      if (respdata + 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;

	  goto out_close;

	}

      /* 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) __readall (sock, resultbuf + 1, datalen) == datalen)

	    {

	      retval = 0;

	      *result = resultbuf;

	    }

	  else

	    {

	      free (resultbuf);

	      *h_errnop = NETDB_INTERNAL;

	    }

	}

      else

	{

	  /* Copy the data in the block.  */

	  memcpy (resultbuf + 1, respdata, datalen);

	  /* Try to detect corrupt databases.  */

	  if (resultbuf->canon != NULL

	      && resultbuf->canon[ai_resp.canonlen - 1] != '\0')

	    /* We cannot use the database.  */

	    {

	      if (mapped->head->gc_cycle != gc_cycle)

		retval = -2;

	      else

		free (resultbuf);

	      goto out_close;

	    }

	  retval = 0;

	  *result = resultbuf;

	}

    }

  else

    {

      if (__glibc_unlikely (ai_resp.found == -1))

	{

	  /* The daemon does not cache this database.  */

	  __nss_not_use_nscd_hosts = 1;

	  goto out_close;

	}

      /* Store the error number.  */

      *h_errnop = ai_resp.error;

      /* Set errno to 0 to indicate no error, just no found record.  */

      __set_errno (0);

      /* Even though we have not found anything, the result is zero.  */

      retval = 0;

    }

 out_close:

  if (sock != -1)

    __close_nocancel_nostatus (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 if possible.  */

      if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)

	{

	  /* nscd is just running gc now.  Disable using the mapping.  */

	  if (atomic_decrement_val (&mapped->counter) == 0)

	    __nscd_unmap (mapped);

	  mapped = NO_MAPPING;

	}

      if (retval != -1)

	{

	  *result = NULL;

	  free (resultbuf);

	  goto retry;

	}

    }

  return retval;

}