/* Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   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 <atomic.h>

#include <errno.h>

#include <stdbool.h>

#include "nsswitch.h"

#include "sysdep.h"

#ifdef USE_NSCD

# include <nscd/nscd_proto.h>

#endif

#ifdef NEED__RES

# include <resolv/resolv_context.h>

#endif

/*******************************************************************\

|* Here we assume several symbols to be defined:		   *|

|*								   *|

|* LOOKUP_TYPE   - the return type of the function		   *|

|*								   *|

|* FUNCTION_NAME - name of the non-reentrant function		   *|

|*								   *|

|* DATABASE_NAME - name of the database the function accesses	   *|

|*		   (e.g., host, services, ...)			   *|

|*								   *|

|* ADD_PARAMS    - additional parameters, can vary in number	   *|

|*								   *|

|* ADD_VARIABLES - names of additional parameters		   *|

|*								   *|

|* Optionally the following vars can be defined:		   *|

|*								   *|

|* EXTRA_PARAMS  - optional parameters, can vary in number	   *|

|*								   *|

|* EXTRA_VARIABLES - names of optional parameter		   *|

|*								   *|

|* FUNCTION2_NAME - alternative name of the non-reentrant function *|

|*								   *|

|* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|

|*		   the global `h_errno' variable.		   *|

|*								   *|

|* NEED__RES     - obtain a struct resolv_context resolver context *|

|*								   *|

|* PREPROCESS    - code run before anything else		   *|

|*								   *|

|* POSTPROCESS   - code run after the lookup			   *|

|*								   *|

\*******************************************************************/

/* To make the real sources a bit prettier.  */

#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)

#ifdef FUNCTION2_NAME

# define REENTRANT2_NAME APPEND_R (FUNCTION2_NAME)

#else

# define REENTRANT2_NAME NULL

#endif

#define APPEND_R(name) APPEND_R1 (name)

#define APPEND_R1(name) name##_r

#define INTERNAL(name) INTERNAL1 (name)

#define INTERNAL1(name) __##name

#define NEW(name) NEW1 (name)

#define NEW1(name) __new_##name

#ifdef USE_NSCD

# define NSCD_NAME ADD_NSCD (REENTRANT_NAME)

# define ADD_NSCD(name) ADD_NSCD1 (name)

# define ADD_NSCD1(name) __nscd_##name

# define NOT_USENSCD_NAME ADD_NOT_NSCDUSE (DATABASE_NAME)

# define ADD_NOT_NSCDUSE(name) ADD_NOT_NSCDUSE1 (name)

# define ADD_NOT_NSCDUSE1(name) __nss_not_use_nscd_##name

# define CONCAT2(arg1, arg2) CONCAT2_2 (arg1, arg2)

# define CONCAT2_2(arg1, arg2) arg1##arg2

#endif

#define FUNCTION_NAME_STRING STRINGIZE (FUNCTION_NAME)

#define REENTRANT_NAME_STRING STRINGIZE (REENTRANT_NAME)

#ifdef FUNCTION2_NAME

# define REENTRANT2_NAME_STRING STRINGIZE (REENTRANT2_NAME)

#else

# define REENTRANT2_NAME_STRING NULL

#endif

#define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)

#define STRINGIZE(name) STRINGIZE1 (name)

#define STRINGIZE1(name) #name

#ifndef DB_LOOKUP_FCT

# define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup2)

# define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)

# define CONCAT3_2(Pre, Name, Post) Pre##Name##Post

#endif

/* Sometimes we need to store error codes in the `h_errno' variable.  */

#ifdef NEED_H_ERRNO

# define H_ERRNO_PARM , int *h_errnop

# define H_ERRNO_VAR , h_errnop

# define H_ERRNO_VAR_P h_errnop

#else

# define H_ERRNO_PARM

# define H_ERRNO_VAR

# define H_ERRNO_VAR_P NULL

#endif

#ifndef EXTRA_PARAMS

# define EXTRA_PARAMS

#endif

#ifndef EXTRA_VARIABLES

# define EXTRA_VARIABLES

#endif

#ifdef HAVE_AF

# define AF_VAL af

#else

# define AF_VAL AF_INET

#endif

/* Set defaults for merge functions that haven't been defined.  */

#ifndef DEEPCOPY_FN

static inline int

__copy_einval (LOOKUP_TYPE a,

	       const size_t b,

	       LOOKUP_TYPE *c,

	       char *d,

	       char **e)

{

  return EINVAL;

}

# define DEEPCOPY_FN __copy_einval

#endif

#ifndef MERGE_FN

static inline int

__merge_einval (LOOKUP_TYPE *a,

		char *b,

		char *c,

		size_t d,

		LOOKUP_TYPE *e,

		char *f)

{

  return EINVAL;

}

# define MERGE_FN __merge_einval

#endif

#define CHECK_MERGE(err, status)		\

  ({						\

    do						\

      {						\

	if (err)				\

	  {					\

	    __set_errno (err);			\

	    if (err == ERANGE)			\

	      status = NSS_STATUS_TRYAGAIN;	\

	    else				\

	      status = NSS_STATUS_UNAVAIL;	\

	    break;				\

	  }					\

      }						\

    while (0);					\

  })

/* Type of the lookup function we need here.  */

typedef enum nss_status (*lookup_function) (ADD_PARAMS, LOOKUP_TYPE *, char *,

					    size_t, int * H_ERRNO_PARM

					    EXTRA_PARAMS);

/* The lookup function for the first entry of this service.  */

extern int DB_LOOKUP_FCT (service_user **nip, const char *name,

			  const char *name2, void **fctp);

libc_hidden_proto (DB_LOOKUP_FCT)

int

INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,

			   size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM

			   EXTRA_PARAMS)

{

  static bool startp_initialized;

  static service_user *startp;

  static lookup_function start_fct;

  service_user *nip;

  int do_merge = 0;

  LOOKUP_TYPE mergegrp;

  char *mergebuf = NULL;

  char *endptr = NULL;

  union

  {

    lookup_function l;

    void *ptr;

  } fct;

  int no_more, err;

  enum nss_status status = NSS_STATUS_UNAVAIL;

#ifdef USE_NSCD

  int nscd_status;

#endif

#ifdef NEED_H_ERRNO

  bool any_service = false;

#endif

#ifdef NEED__RES

  /* The HANDLE_DIGITS_DOTS case below already needs the resolver

     configuration, so this has to happen early.  */

  struct resolv_context *res_ctx = __resolv_context_get ();

  if (res_ctx == NULL)

    {

      *h_errnop = NETDB_INTERNAL;

      *result = NULL;

      return errno;

    }

#endif /* NEED__RES */

#ifdef PREPROCESS

  PREPROCESS;

#endif

#ifdef HANDLE_DIGITS_DOTS

  switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,

				      buflen, result, &status, AF_VAL,

				      H_ERRNO_VAR_P))

    {

    case -1:

# ifdef NEED__RES

      __resolv_context_put (res_ctx);

# endif

      return errno;

    case 1:

#ifdef NEED_H_ERRNO

      any_service = true;

#endif

      goto done;

    }

#endif

#ifdef USE_NSCD

  if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)

    NOT_USENSCD_NAME = 0;

  if (!NOT_USENSCD_NAME

      && !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])

    {

      nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result

			       H_ERRNO_VAR);

      if (nscd_status >= 0)

	{

# ifdef NEED__RES

	  __resolv_context_put (res_ctx);

# endif

	  return nscd_status;

	}

    }

#endif

  if (! startp_initialized)

    {

      no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,

			       REENTRANT2_NAME_STRING, &fct.ptr);

      if (no_more)

	{

	  void *tmp_ptr = (service_user *) -1l;

#ifdef PTR_MANGLE

	  PTR_MANGLE (tmp_ptr);

#endif

	  startp = tmp_ptr;

	}

      else

	{

	  void *tmp_ptr = fct.l;

#ifdef PTR_MANGLE

	  PTR_MANGLE (tmp_ptr);

#endif

	  start_fct = tmp_ptr;

	  tmp_ptr = nip;

#ifdef PTR_MANGLE

	  PTR_MANGLE (tmp_ptr);

#endif

	  startp = tmp_ptr;

	}

      /* Make sure start_fct and startp are written before

	 startp_initialized.  */

      atomic_write_barrier ();

      startp_initialized = true;

    }

  else

    {

      fct.l = start_fct;

      nip = startp;

#ifdef PTR_DEMANGLE

      PTR_DEMANGLE (fct.l);

      PTR_DEMANGLE (nip);

#endif

      no_more = nip == (service_user *) -1l;

    }

  while (no_more == 0)

    {

#ifdef NEED_H_ERRNO

      any_service = true;

#endif

      status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,

				    &errno H_ERRNO_VAR EXTRA_VARIABLES));

      /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the

	 provided buffer is too small.  In this case we should give

	 the user the possibility to enlarge the buffer and we should

	 not simply go on with the next service (even if the TRYAGAIN

	 action tells us so).  */

      if (status == NSS_STATUS_TRYAGAIN

#ifdef NEED_H_ERRNO

	  && *h_errnop == NETDB_INTERNAL

#endif

	  && errno == ERANGE)

	break;

      if (do_merge)

	{

	  if (status == NSS_STATUS_SUCCESS)

	    {

	      /* The previous loop saved a buffer for merging.

		 Perform the merge now.  */

	      err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,

			      buffer);

	      CHECK_MERGE (err,status);

	      do_merge = 0;

	    }

	  else

	    {

	      /* If the result wasn't SUCCESS, copy the saved buffer back

	         into the result buffer and set the status back to

	         NSS_STATUS_SUCCESS to match the previous pass through the

	         loop.

	          * If the next action is CONTINUE, it will overwrite the value

	            currently in the buffer and return the new value.

	          * If the next action is RETURN, we'll return the previously-

	            acquired values.

	          * If the next action is MERGE, then it will be added to the

	            buffer saved from the previous source.  */

	      err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);

	      CHECK_MERGE (err, status);

	      status = NSS_STATUS_SUCCESS;

	    }

	}

      /* If we were are configured to merge this value with the next one,

         save the current value of the group struct.  */

      if (nss_next_action (nip, status) == NSS_ACTION_MERGE

	  && status == NSS_STATUS_SUCCESS)

	{

	  /* Copy the current values into a buffer to be merged with the next

	     set of retrieved values.  */

	  if (mergebuf == NULL)

	    {

	      /* Only allocate once and reuse it for as many merges as we need

	         to perform.  */

	      mergebuf = malloc (buflen);

	      if (mergebuf == NULL)

		{

		  __set_errno (ENOMEM);

		  status = NSS_STATUS_UNAVAIL;

		  break;

		}

	    }

	  err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);

	  CHECK_MERGE (err, status);

	  do_merge = 1;

	}

      no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,

			     REENTRANT2_NAME_STRING, &fct.ptr, status, 0);

    }

  free (mergebuf);

  mergebuf = NULL;

#ifdef HANDLE_DIGITS_DOTS

done:

#endif

  *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;

#ifdef NEED_H_ERRNO

  if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)

    /* This happens when we weren't able to use a service for reasons other

       than the module not being found.  In such a case, we'd want to tell the

       caller that errno has the real reason for failure.  */

    *h_errnop = NETDB_INTERNAL;

  else if (status != NSS_STATUS_SUCCESS && !any_service)

    /* We were not able to use any service.  */

    *h_errnop = NO_RECOVERY;

#endif

#ifdef POSTPROCESS

  POSTPROCESS;

#endif

#ifdef NEED__RES

  /* This has to happen late because the POSTPROCESS stage above might

     need the resolver context.  */

  __resolv_context_put (res_ctx);

#endif /* NEED__RES */

  int res;

  if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)

    res = 0;

  /* Don't pass back ERANGE if this is not for a too-small buffer.  */

  else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)

    res = EINVAL;

#ifdef NEED_H_ERRNO

  /* These functions only set errno if h_errno is NETDB_INTERNAL.  */

  else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)

    res = EAGAIN;

#endif

  else

    return errno;

  __set_errno (res);

  return res;

}

#ifdef NO_COMPAT_NEEDED

strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);

#elif !defined FUNCTION2_NAME

# include <shlib-compat.h>

# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)

#  define OLD(name) OLD1 (name)

#  define OLD1(name) __old_##name

int

attribute_compat_text_section

OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,

		      size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)

{

  int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,

				       buflen, result H_ERRNO_VAR);

  if (ret != 0 || result == NULL)

    ret = -1;

  return ret;

}

#  define do_symbol_version(real, name, version) \

  compat_symbol (libc, real, name, version)

do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);

# endif

/* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias

   in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not

   hidden too.  */

strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));

# define do_default_symbol_version(real, name, version) \

  versioned_symbol (libc, real, name, version)

do_default_symbol_version (NEW (REENTRANT_NAME),

			   REENTRANT_NAME, GLIBC_2_1_2);

#endif

nss_interface_function (REENTRANT_NAME)