nss/getnssent_r.c

   1 /* Copyright (C) 2000-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <netdb.h>
  20 #include "nsswitch.h"
  21 #include <resolv/resolv_context.h>
  22
  23 /* Set up NIP to run through the services.  If ALL is zero, use NIP's
  24    current location if it's not nil.  Return nonzero if there are no
  25    services (left).  */
  26 static int
  27 setup (const char *func_name, db_lookup_function lookup_fct,
  28        void **fctp, nss_action_list *nip, nss_action_list *startp, int all)
  29 {
  30   int no_more;
  31   if (*startp == NULL || all)
  32     {
  33       no_more = lookup_fct (nip, func_name, NULL, fctp);
  34       *startp = no_more ? (nss_action_list) -1l : *nip;
  35     }
  36   else if (*startp == (nss_action_list) -1l)
  37     /* No services at all.  */
  38     return 1;
  39   else
  40     {
  41       if (!*nip)
  42         /* Reset to the beginning of the service list.  */
  43         *nip = *startp;
  44       /* Look up the first function.  */
  45       no_more = __nss_lookup (nip, func_name, NULL, fctp);
  46     }
  47   return no_more;
  48 }
  49 \f
  50 void
  51 __nss_setent (const char *func_name, db_lookup_function lookup_fct,
  52               nss_action_list *nip, nss_action_list *startp,
  53               nss_action_list *last_nip, int stayopen, int *stayopen_tmp,
  54               int res)
  55 {
  56   union
  57   {
  58     setent_function f;
  59     void *ptr;
  60   } fct;
  61   int no_more;
  62
  63   struct resolv_context *res_ctx = NULL;
  64   if (res)
  65     {
  66       res_ctx = __resolv_context_get ();
  67       if (res_ctx == NULL)
  68         {
  69           __set_h_errno (NETDB_INTERNAL);
  70           return;
  71         }
  72     }
  73
  74   /* Cycle through the services and run their `setXXent' functions until
  75      we find an available service.  */
  76   no_more = setup (func_name, lookup_fct, &fct.ptr, nip,
  77                    startp, 1);
  78   while (! no_more)
  79     {
  80       int is_last_nip = *nip == *last_nip;
  81       enum nss_status status;
  82
  83       if (stayopen_tmp)
  84         status = DL_CALL_FCT (fct.f, (*stayopen_tmp));
  85       else
  86         status = DL_CALL_FCT (fct.f, (0));
  87
  88
  89       /* This is a special-case.  When [SUCCESS=merge] is in play,
  90          _nss_next2() will skip to the next database.  Due to the
  91          implementation of that function, we can't know whether we're
  92          in an enumeration or an individual lookup, which behaves
  93          differently with regards to merging.  We'll treat SUCCESS as
  94          an indication to start the enumeration at this database. */
  95       if (nss_next_action (*nip, status) == NSS_ACTION_MERGE)
  96         no_more = 1;
  97       else
  98         no_more = __nss_next2 (nip, func_name, NULL, &fct.ptr, status, 0);
  99
 100       if (is_last_nip)
 101         *last_nip = *nip;
 102     }
 103
 104   __resolv_context_put (res_ctx);
 105
 106   if (stayopen_tmp)
 107     *stayopen_tmp = stayopen;
 108 }
 109
 110
 111 void
 112 __nss_endent (const char *func_name, db_lookup_function lookup_fct,
 113               nss_action_list *nip, nss_action_list *startp,
 114               nss_action_list *last_nip, int res)
 115 {
 116   union
 117   {
 118     endent_function f;
 119     void *ptr;
 120   } fct;
 121   int no_more;
 122
 123   struct resolv_context *res_ctx = NULL;
 124   if (res)
 125     {
 126       res_ctx = __resolv_context_get ();
 127       if (res_ctx == NULL)
 128         {
 129           __set_h_errno (NETDB_INTERNAL);
 130           return;
 131         }
 132     }
 133
 134   /* Cycle through all the services and run their endXXent functions.  */
 135   no_more = setup (func_name, lookup_fct, &fct.ptr, nip, startp, 1);
 136   while (! no_more)
 137     {
 138       /* Ignore status, we force check in __NSS_NEXT.  */
 139       DL_CALL_FCT (fct.f, ());
 140
 141       if (*nip == *last_nip)
 142         /* We have processed all services which were used.  */
 143         break;
 144
 145       no_more = __nss_next2 (nip, func_name, NULL, &fct.ptr, 0, 1);
 146     }
 147   *last_nip = *nip = NULL;
 148
 149   __resolv_context_put (res_ctx);
 150 }
 151
 152
 153 int
 154 __nss_getent_r (const char *getent_func_name,
 155                 const char *setent_func_name,
 156                 db_lookup_function lookup_fct,
 157                 nss_action_list *nip, nss_action_list *startp,
 158                 nss_action_list *last_nip, int *stayopen_tmp, int res,
 159                 void *resbuf, char *buffer, size_t buflen,
 160                 void **result, int *h_errnop)
 161 {
 162   union
 163   {
 164     getent_function f;
 165     void *ptr;
 166   } fct;
 167   int no_more;
 168   enum nss_status status;
 169
 170   struct resolv_context *res_ctx = NULL;
 171   if (res)
 172     {
 173       res_ctx = __resolv_context_get ();
 174       if (res_ctx == NULL)
 175         {
 176           *h_errnop = NETDB_INTERNAL;
 177           *result = NULL;
 178           return errno;
 179         }
 180     }
 181
 182   /* Initialize status to return if no more functions are found.  */
 183   status = NSS_STATUS_NOTFOUND;
 184
 185   /* Run through available functions, starting with the same function last
 186      run.  We will repeat each function as long as it succeeds, and then go
 187      on to the next service action.  */
 188   no_more = setup (getent_func_name, lookup_fct, &fct.ptr, nip,
 189                    startp, 0);
 190   while (! no_more)
 191     {
 192       int is_last_nip = *nip == *last_nip;
 193
 194       status = DL_CALL_FCT (fct.f,
 195                             (resbuf, buffer, buflen, &errno, &h_errno));
 196
 197       /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
 198          provided buffer is too small.  In this case we should give
 199          the user the possibility to enlarge the buffer and we should
 200          not simply go on with the next service (even if the TRYAGAIN
 201          action tells us so).  */
 202       if (status == NSS_STATUS_TRYAGAIN
 203           && (h_errnop == NULL || *h_errnop == NETDB_INTERNAL)
 204           && errno == ERANGE)
 205         break;
 206
 207       do
 208         {
 209         /* This is a special-case.  When [SUCCESS=merge] is in play,
 210            _nss_next2() will skip to the next database.  Due to the
 211            implementation of that function, we can't know whether we're
 212            in an enumeration or an individual lookup, which behaves
 213            differently with regards to merging.  We'll treat SUCCESS as
 214            an indication to return the results here. */
 215           if (status == NSS_STATUS_SUCCESS
 216               && nss_next_action (*nip, status) == NSS_ACTION_MERGE)
 217             no_more = 1;
 218           else
 219             no_more = __nss_next2 (nip, getent_func_name, NULL, &fct.ptr,
 220                                    status, 0);
 221
 222           if (is_last_nip)
 223             *last_nip = *nip;
 224
 225           if (! no_more)
 226             {
 227               /* Call the `setXXent' function.  This wasn't done before.  */
 228               union
 229               {
 230                 setent_function f;
 231                 void *ptr;
 232               } sfct;
 233
 234               no_more = __nss_lookup (nip, setent_func_name, NULL, &sfct.ptr);
 235
 236               if (! no_more)
 237                 {
 238                   if (stayopen_tmp)
 239                     status = DL_CALL_FCT (sfct.f, (*stayopen_tmp));
 240                   else
 241                     status = DL_CALL_FCT (sfct.f, (0));
 242                 }
 243               else
 244                 status = NSS_STATUS_NOTFOUND;
 245             }
 246         }
 247       while (! no_more && status != NSS_STATUS_SUCCESS);
 248     }
 249
 250   __resolv_context_put (res_ctx);
 251
 252   *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
 253   return (status == NSS_STATUS_SUCCESS ? 0
 254           : status != NSS_STATUS_TRYAGAIN ? ENOENT
 255           /* h_errno functions only set errno if h_errno is NETDB_INTERNAL.  */
 256           : (h_errnop == NULL || *h_errnop == NETDB_INTERNAL) ? errno
 257           : EAGAIN);
 258 }