text: /* Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
     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 <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 (__builtin_expect (__nss_have_localdomain >= 0, 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 (__builtin_expect (ai_resp.found == -1, 0))
  	{
  	  /* 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_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 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;
  }
  