/* Copyright (C) 1998-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.

   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 <errno.h>

#include <resolv/resolv-internal.h>

#include <stdio.h>

#include <string.h>

#include <stdint.h>

#include <arpa/nameser.h>

#include <not-cancel.h>

#include "nscd-client.h"

#include "nscd_proto.h"

int __nss_not_use_nscd_hosts;

static int nscd_gethst_r (const char *key, size_t keylen, request_type type,

			  struct hostent *resultbuf, char *buffer,

			  size_t buflen, struct hostent **result,

			  int *h_errnop);

int

__nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,

			char *buffer, size_t buflen, struct hostent **result,

			int *h_errnop)

{

  request_type reqtype;

  reqtype = res_use_inet6 () ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;

  return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,

			buffer, buflen, result, h_errnop);

}

int

__nscd_gethostbyname2_r (const char *name, int af, struct hostent *resultbuf,

			 char *buffer, size_t buflen, struct hostent **result,

			 int *h_errnop)

{

  request_type reqtype;

  reqtype = af == AF_INET6 ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;

  return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,

			buffer, buflen, result, h_errnop);

}

int

__nscd_gethostbyaddr_r (const void *addr, socklen_t len, int type,

			struct hostent *resultbuf, char *buffer, size_t buflen,

			struct hostent **result, int *h_errnop)

{

  request_type reqtype;

  if (!((len == INADDRSZ && type == AF_INET)

	|| (len == IN6ADDRSZ && type == AF_INET6)))

    /* LEN and TYPE do not match.  */

    return -1;

  reqtype = type == AF_INET6 ? GETHOSTBYADDRv6 : GETHOSTBYADDR;

  return nscd_gethst_r (addr, len, reqtype, resultbuf, buffer, buflen, result,

			h_errnop);

}

libc_locked_map_ptr (, __hst_map_handle) attribute_hidden;

/* 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 (hst_map_free)

{

  if (__hst_map_handle.mapped != NO_MAPPING)

    {

      void *p = __hst_map_handle.mapped;

      __hst_map_handle.mapped = NO_MAPPING;

      free (p);

    }

}

uint32_t

__nscd_get_nl_timestamp (void)

{

  uint32_t retval;

  if (__nss_not_use_nscd_hosts != 0)

    return 0;

  /* __nscd_get_mapping can change hst_map_handle.mapped to NO_MAPPING.

   However, __nscd_get_mapping assumes the prior value was not NO_MAPPING.

   Thus we have to acquire the lock to prevent this thread from changing

   hst_map_handle.mapped to NO_MAPPING while another thread is inside

    __nscd_get_mapping.  */

  if (!__nscd_acquire_maplock (&__hst_map_handle))

    return 0;

  struct mapped_database *map = __hst_map_handle.mapped;

  if (map == NULL

      || (map != NO_MAPPING

	  && map->head->nscd_certainly_running == 0

	  && map->head->timestamp + MAPPING_TIMEOUT < time (NULL)))

    map = __nscd_get_mapping (GETFDHST, "hosts", &__hst_map_handle.mapped);

  if (map == NO_MAPPING)

    retval = 0;

  else

    retval = map->head->extra_data[NSCD_HST_IDX_CONF_TIMESTAMP];

  /* Release the lock.  */

  __hst_map_handle.lock = 0;

  return retval;

}

int __nss_have_localdomain attribute_hidden;

static int

nscd_gethst_r (const char *key, size_t keylen, request_type type,

	       struct hostent *resultbuf, char *buffer, size_t buflen,

	       struct hostent **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;

	}

    }

  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:;

  const char *h_name = NULL;

  const uint32_t *aliases_len = NULL;

  const char *addr_list = NULL;

  size_t addr_list_len = 0;

  int retval = -1;

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

  int sock = -1;

  hst_response_header hst_resp;

  if (mapped != NO_MAPPING)

    {

      /* No const qualifier, as it can change during garbage collection.  */

      struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,

						    sizeof hst_resp);

      if (found != NULL)

	{

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

	  hst_resp = found->data[0].hstdata;

	  aliases_len = (uint32_t *) (h_name + hst_resp.h_name_len);

	  addr_list = ((char *) aliases_len

		       + hst_resp.h_aliases_cnt * sizeof (uint32_t));

	  addr_list_len = hst_resp.h_addr_list_cnt * INADDRSZ;

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

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

	     in progress, it can contain anything.  */

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

	    {

	      retval = -2;

	      goto out;

	    }

#if !_STRING_ARCH_unaligned

	  /* The aliases_len array in the mapped database might very

	     well be unaligned.  We will access it word-wise so on

	     platforms which do not tolerate unaligned accesses we

	     need to make an aligned copy.  */

	  if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))

	      != 0)

	    {

	      uint32_t *tmp = alloca (hst_resp.h_aliases_cnt

				      * sizeof (uint32_t));

	      aliases_len = memcpy (tmp, aliases_len,

				    hst_resp.h_aliases_cnt

				    * sizeof (uint32_t));

	    }

#endif

	  if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)

	    {

	      if (hst_resp.h_length == INADDRSZ)

		addr_list += addr_list_len;

	      addr_list_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;

	    }

	  if (__builtin_expect ((const char *) addr_list + addr_list_len

				> recend, 0))

	    goto out;

	}

    }

  if (h_name == NULL)

    {

      sock = __nscd_open_socket (key, keylen, type, &hst_resp,

				 sizeof (hst_resp));

      if (sock == -1)

	{

	  __nss_not_use_nscd_hosts = 1;

	  goto out;

	}

    }

  /* No value found so far.  */

  *result = NULL;

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

    {

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

      __nss_not_use_nscd_hosts = 1;

      goto out_close;

    }

  if (hst_resp.found == 1)

    {

      char *cp = buffer;

      uintptr_t align1;

      uintptr_t align2;

      size_t total_len;

      ssize_t cnt;

      char *ignore;

      int n;

      /* A first check whether the buffer is sufficiently large is possible.  */

      /* Now allocate the buffer the array for the group members.  We must

	 align the pointer and the base of the h_addr_list pointers.  */

      align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))

		& (__alignof__ (char *) - 1));

      align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp.h_name_len)

					 - ((char *) 0)))

		& (__alignof__ (char *) - 1));

      if (buflen < (align1 + hst_resp.h_name_len + align2

		    + ((hst_resp.h_aliases_cnt + hst_resp.h_addr_list_cnt

			+ 2)

		       * sizeof (char *))

		    + hst_resp.h_addr_list_cnt * (type == AF_INET

						  ? INADDRSZ : IN6ADDRSZ)))

	{

	no_room:

	  *h_errnop = NETDB_INTERNAL;

	  __set_errno (ERANGE);

	  retval = ERANGE;

	  goto out_close;

	}

      cp += align1;

      /* Prepare the result as far as we can.  */

      resultbuf->h_aliases = (char **) cp;

      cp += (hst_resp.h_aliases_cnt + 1) * sizeof (char *);

      resultbuf->h_addr_list = (char **) cp;

      cp += (hst_resp.h_addr_list_cnt + 1) * sizeof (char *);

      resultbuf->h_name = cp;

      cp += hst_resp.h_name_len + align2;

      if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)

	{

	  resultbuf->h_addrtype = AF_INET;

	  resultbuf->h_length = INADDRSZ;

	}

      else

	{

	  resultbuf->h_addrtype = AF_INET6;

	  resultbuf->h_length = IN6ADDRSZ;

	}

      for (cnt = 0; cnt < hst_resp.h_addr_list_cnt; ++cnt)

	{

	  resultbuf->h_addr_list[cnt] = cp;

	  cp += resultbuf->h_length;

	}

      resultbuf->h_addr_list[cnt] = NULL;

      if (h_name == NULL)

	{

	  struct iovec vec[4];

	  vec[0].iov_base = resultbuf->h_name;

	  vec[0].iov_len = hst_resp.h_name_len;

	  total_len = hst_resp.h_name_len;

	  n = 1;

	  if (hst_resp.h_aliases_cnt > 0)

	    {

	      aliases_len = alloca (hst_resp.h_aliases_cnt

				    * sizeof (uint32_t));

	      vec[n].iov_base = (void *) aliases_len;

	      vec[n].iov_len = hst_resp.h_aliases_cnt * sizeof (uint32_t);

	      total_len += hst_resp.h_aliases_cnt * sizeof (uint32_t);

	      ++n;

	    }

	  if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)

	    {

	      vec[n].iov_base = resultbuf->h_addr_list[0];

	      vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;

	      total_len += hst_resp.h_addr_list_cnt * INADDRSZ;

	      ++n;

	    }

	  else

	    {

	      if (hst_resp.h_length == INADDRSZ)

		{

		  ignore = alloca (hst_resp.h_addr_list_cnt * INADDRSZ);

		  vec[n].iov_base = ignore;

		  vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;

		  total_len += hst_resp.h_addr_list_cnt * INADDRSZ;

		  ++n;

		}

	      vec[n].iov_base = resultbuf->h_addr_list[0];

	      vec[n].iov_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;

	      total_len += hst_resp.h_addr_list_cnt * IN6ADDRSZ;

	      ++n;

	    }

	  if ((size_t) __readvall (sock, vec, n) != total_len)

	    goto out_close;

	}

      else

	{

	  memcpy (resultbuf->h_name, h_name, hst_resp.h_name_len);

	  memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);

	}

      /*  Now we also can read the aliases.  */

      total_len = 0;

      for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)

	{

	  resultbuf->h_aliases[cnt] = cp;

	  cp += aliases_len[cnt];

	  total_len += aliases_len[cnt];

	}

      resultbuf->h_aliases[cnt] = NULL;

      if (__builtin_expect ((const char *) addr_list + addr_list_len

			    + total_len > recend, 0))

	{

	  /* aliases_len array might contain garbage during nscd GC cycle,

	     retry rather than fail in that case.  */

	  if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)

	    retval = -2;

	  goto out_close;

	}

      /* See whether this would exceed the buffer capacity.  */

      if (__glibc_unlikely (cp > buffer + buflen))

	{

	  /* aliases_len array might contain garbage during nscd GC cycle,

	     retry rather than fail in that case.  */

	  if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)

	    {

	      retval = -2;

	      goto out_close;

	    }

	  goto no_room;

	}

      /* And finally read the aliases.  */

      if (addr_list == NULL)

	{

	  if (total_len == 0

	      || ((size_t) __readall (sock, resultbuf->h_aliases[0], total_len)

		  == total_len))

	    {

	      retval = 0;

	      *result = resultbuf;

	    }

	}

      else

	{

	  memcpy (resultbuf->h_aliases[0],

		  (const char *) addr_list + addr_list_len, total_len);

	  /* Try to detect corrupt databases.  */

	  if (resultbuf->h_name[hst_resp.h_name_len - 1] != '\0'

	      || ({for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)

		     if (resultbuf->h_aliases[cnt][aliases_len[cnt] - 1]

			 != '\0')

		       break;

		   cnt < hst_resp.h_aliases_cnt; }))

	    {

	      /* We cannot use the database.  */

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

		retval = -2;

	      goto out_close;

	    }

	  retval = 0;

	  *result = resultbuf;

	}

    }

  else

    {

      /* Store the error number.  */

      *h_errnop = hst_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)

	goto retry;

    }

  return retval;

}