/* Copyright (C) 2007-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@redhat.com>, 2007.

   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 <string.h>

#include <not-cancel.h>

#include <_itoa.h>

#include <stdint.h>

#include "nscd-client.h"

#include "nscd_proto.h"

int __nss_not_use_nscd_services;

static int nscd_getserv_r (const char *crit, size_t critlen, const char *proto,

			   request_type type, struct servent *resultbuf,

			   char *buf, size_t buflen, struct servent **result);

int

__nscd_getservbyname_r (const char *name, const char *proto,

			struct servent *result_buf, char *buf, size_t buflen,

			struct servent **result)

{

  return nscd_getserv_r (name, strlen (name), proto, GETSERVBYNAME, result_buf,

			 buf, buflen, result);

}

int

__nscd_getservbyport_r (int port, const char *proto,

			struct servent *result_buf, char *buf, size_t buflen,

			struct servent **result)

{

  char portstr[3 * sizeof (int) + 2];

  portstr[sizeof (portstr) - 1] = '\0';

  char *cp = _itoa_word (port, portstr + sizeof (portstr) - 1, 10, 0);

  return nscd_getserv_r (cp, portstr + sizeof (portstr) - 1 - cp, proto,

			 GETSERVBYPORT, result_buf, buf, buflen, result);

}

libc_locked_map_ptr (, __serv_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 (serv_map_free)

{

  if (__serv_map_handle.mapped != NO_MAPPING)

    {

      void *p = __serv_map_handle.mapped;

      __serv_map_handle.mapped = NO_MAPPING;

      free (p);

    }

}

static int

nscd_getserv_r (const char *crit, size_t critlen, const char *proto,

		request_type type, struct servent *resultbuf,

		char *buf, size_t buflen, struct servent **result)

{

  int gc_cycle;

  int nretries = 0;

  size_t alloca_used = 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 (GETFDSERV, "services", &__serv_map_handle,

			       &gc_cycle);

  size_t protolen = proto == NULL ? 0 : strlen (proto);

  size_t keylen = critlen + 1 + protolen + 1;

  int alloca_key = __libc_use_alloca (keylen);

  char *key;

  if (alloca_key)

    key = alloca_account (keylen, alloca_used);

  else

    {

      key = malloc (keylen);

      if (key == NULL)

	return -1;

    }

  memcpy (__mempcpy (__mempcpy (key, crit, critlen),

		     "/", 1), proto ?: "", protolen + 1);

 retry:;

  const char *s_name = NULL;

  const char *s_proto = NULL;

  int alloca_aliases_len = 0;

  const uint32_t *aliases_len = NULL;

  const char *aliases_list = NULL;

  int retval = -1;

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

  int sock = -1;

  serv_response_header serv_resp;

  if (mapped != NO_MAPPING)

    {

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

						    sizeof serv_resp);

      if (found != NULL)

	{

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

	  serv_resp = found->data[0].servdata;

	  s_proto = s_name + serv_resp.s_name_len;

	  alloca_aliases_len = 1;

	  aliases_len = (uint32_t *) (s_proto + serv_resp.s_proto_len);

	  aliases_list = ((char *) aliases_len

			  + serv_resp.s_aliases_cnt * sizeof (uint32_t));

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

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

	     in progress, it can contain anything.  */

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

	    {

	      retval = -2;

	      goto out;

	    }

	  if (__builtin_expect ((const char *) aliases_len

				+ serv_resp.s_aliases_cnt * sizeof (uint32_t)

				> recend, 0))

	    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_aliases_len

		= __libc_use_alloca (alloca_used

				     + (serv_resp.s_aliases_cnt

					* sizeof (uint32_t)));

	      if (alloca_aliases_len)

		tmp = alloca_account (serv_resp.s_aliases_cnt

				      * sizeof (uint32_t),

				      alloca_used);

	      else

		{

		  tmp = malloc (serv_resp.s_aliases_cnt * sizeof (uint32_t));

		  if (tmp == NULL)

		    {

		      retval = ENOMEM;

		      goto out;

		    }

		}

	      aliases_len = memcpy (tmp, aliases_len,

				    serv_resp.s_aliases_cnt

				    * sizeof (uint32_t));

	    }

#endif

	}

    }

  if (s_name == NULL)

    {

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

				 sizeof (serv_resp));

      if (sock == -1)

	{

	  __nss_not_use_nscd_services = 1;

	  goto out;

	}

    }

  /* No value found so far.  */

  *result = NULL;

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

    {

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

      __nss_not_use_nscd_services = 1;

      goto out_close;

    }

  if (serv_resp.found == 1)

    {

      char *cp = buf;

      uintptr_t align1;

      uintptr_t align2;

      size_t total_len;

      ssize_t cnt;

      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 + serv_resp.s_name_len

					  + serv_resp.s_proto_len)

					 - ((char *) 0)))

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

      if (buflen < (align1 + serv_resp.s_name_len + serv_resp.s_proto_len

		    + align2

		    + (serv_resp.s_aliases_cnt + 1) * sizeof (char *)))

	{

	no_room:

	  __set_errno (ERANGE);

	  retval = ERANGE;

	  goto out_close;

	}

      cp += align1;

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

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

      cp += (serv_resp.s_aliases_cnt + 1) * sizeof (char *);

      resultbuf->s_name = cp;

      cp += serv_resp.s_name_len;

      resultbuf->s_proto = cp;

      cp += serv_resp.s_proto_len + align2;

      resultbuf->s_port = serv_resp.s_port;

      if (s_name == NULL)

	{

	  struct iovec vec[2];

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

	  vec[0].iov_len = serv_resp.s_name_len + serv_resp.s_proto_len;

	  total_len = vec[0].iov_len;

	  n = 1;

	  if (serv_resp.s_aliases_cnt > 0)

	    {

	      assert (alloca_aliases_len == 0);

	      alloca_aliases_len

		= __libc_use_alloca (alloca_used

				     + (serv_resp.s_aliases_cnt

					* sizeof (uint32_t)));

	      if (alloca_aliases_len)

		aliases_len = alloca_account (serv_resp.s_aliases_cnt

					      * sizeof (uint32_t),

					      alloca_used);

	      else

		{

		  aliases_len = malloc (serv_resp.s_aliases_cnt

					* sizeof (uint32_t));

		  if (aliases_len == NULL)

		    {

		      retval = ENOMEM;

		      goto out_close;

		    }

		}

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

	      vec[n].iov_len = serv_resp.s_aliases_cnt * sizeof (uint32_t);

	      total_len += serv_resp.s_aliases_cnt * sizeof (uint32_t);

	      ++n;

	    }

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

	    goto out_close;

	}

      else

	memcpy (resultbuf->s_name, s_name,

		serv_resp.s_name_len + serv_resp.s_proto_len);

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

      total_len = 0;

      for (cnt = 0; cnt < serv_resp.s_aliases_cnt; ++cnt)

	{

	  resultbuf->s_aliases[cnt] = cp;

	  cp += aliases_len[cnt];

	  total_len += aliases_len[cnt];

	}

      resultbuf->s_aliases[cnt] = NULL;

      if (__builtin_expect ((const char *) aliases_list + total_len > recend,

			    0))

	{

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

	     retry rather than fail in that case.  */

	  if (aliases_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 > buf + buflen))

	{

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

	     retry rather than fail in that case.  */

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

	    {

	      retval = -2;

	      goto out_close;

	    }

	  goto no_room;

	}

      /* And finally read the aliases.  */

      if (aliases_list == NULL)

	{

	  if (total_len == 0

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

		  == total_len))

	    {

	      retval = 0;

	      *result = resultbuf;

	    }

	}

      else

	{

	  memcpy (resultbuf->s_aliases[0], aliases_list, total_len);

	  /* Try to detect corrupt databases.  */

	  if (resultbuf->s_name[serv_resp.s_name_len - 1] != '\0'

	      || resultbuf->s_proto[serv_resp.s_proto_len - 1] != '\0'

	      || ({for (cnt = 0; cnt < serv_resp.s_aliases_cnt; ++cnt)

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

			 != '\0')

		       break;

		   cnt < serv_resp.s_aliases_cnt; }))

	    {

	      /* We cannot use the database.  */

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

		retval = -2;

	      goto out_close;

	    }

	  retval = 0;

	  *result = resultbuf;

	}

    }

  else

    {

      /* 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)

	{

	  if (!alloca_aliases_len)

	    free ((void *) aliases_len);

	  goto retry;

	}

    }

  if (!alloca_aliases_len)

    free ((void *) aliases_len);

  if (!alloca_key)

    free (key);

  return retval;

}