nss/nsswitch.h

   1 /* Copyright (C) 1996-2024 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 #ifndef _NSSWITCH_H
  19 #define _NSSWITCH_H     1
  20
  21 /* This is an *internal* header.  */
  22
  23 #include <arpa/nameser.h>
  24 #include <netinet/in.h>
  25 #include <nss.h>
  26 #include <resolv.h>
  27 #include <search.h>
  28 #include <dlfcn.h>
  29 #include <stdbool.h>
  30
  31 /* Actions performed after lookup finished.  */
  32 typedef enum
  33 {
  34   NSS_ACTION_CONTINUE,
  35   NSS_ACTION_RETURN,
  36   NSS_ACTION_MERGE
  37 } lookup_actions;
  38
  39 struct nss_action;
  40
  41 typedef struct service_library
  42 {
  43   /* Name of service (`files', `dns', `nis', ...).  */
  44   const char *name;
  45   /* Pointer to the loaded shared library.  */
  46   void *lib_handle;
  47   /* And the link to the next entry.  */
  48   struct service_library *next;
  49 } service_library;
  50
  51
  52 /* For mapping a function name to a function pointer.  It is known in
  53    nsswitch.c:nss_lookup_function that a string pointer for the lookup key
  54    is the first member.  */
  55 typedef struct
  56 {
  57   const char *fct_name;
  58   void *fct_ptr;
  59 } known_function;
  60
  61
  62 /* To access the action based on the status value use this macro.  */
  63 #define nss_next_action(ni, status) nss_action_get (ni, status)
  64
  65
  66 #ifdef USE_NSCD
  67 /* Indices into DATABASES in nsswitch.c and __NSS_DATABASE_CUSTOM.  */
  68 enum
  69   {
  70 # define DEFINE_DATABASE(arg) NSS_DBSIDX_##arg,
  71 # include "databases.def"
  72 # undef DEFINE_DATABASE
  73     NSS_DBSIDX_max
  74   };
  75
  76 /* Flags whether custom rules for database is set.  */
  77 extern bool __nss_database_custom[NSS_DBSIDX_max] attribute_hidden;
  78 #endif
  79
  80 /* Warning for NSS functions, which don't require dlopen if glibc
  81    was built with --enable-static-nss.  */
  82 #ifdef DO_STATIC_NSS
  83 # define nss_interface_function(name)
  84 #else
  85 # define nss_interface_function(name) static_link_warning (name)
  86 #endif
  87
  88
  89 /* Interface functions for NSS.  */
  90
  91 /* Put first function with name FCT_NAME for SERVICE in FCTP.  The
  92    position is remembered in NI.  The function returns a value < 0 if
  93    an error occurred or no such function exists.  */
  94 extern int __nss_lookup (struct nss_action **ni, const char *fct_name,
  95                          const char *fct2_name, void **fctp);
  96 libc_hidden_proto (__nss_lookup)
  97
  98 /* Determine the next step in the lookup process according to the
  99    result STATUS of the call to the last function returned by
 100    `__nss_lookup' or `__nss_next'.  NI specifies the last function
 101    examined.  The function return a value > 0 if the process should
 102    stop with the last result of the last function call to be the
 103    result of the entire lookup.  The returned value is 0 if there is
 104    another function to use and < 0 if an error occurred.
 105
 106    If ALL_VALUES is nonzero, the return value will not be > 0 as long as
 107    there is a possibility the lookup process can ever use following
 108    services.  In other words, only if all four lookup results have
 109    the action RETURN associated the lookup process stops before the
 110    natural end.  */
 111 extern int __nss_next2 (struct nss_action **ni, const char *fct_name,
 112                         const char *fct2_name, void **fctp, int status,
 113                         int all_values) attribute_hidden;
 114 libc_hidden_proto (__nss_next2)
 115 extern int __nss_next (struct nss_action **ni, const char *fct_name, void **fctp,
 116                        int status, int all_values);
 117
 118 /* Search for the service described in NI for a function named FCT_NAME
 119    and return a pointer to this function if successful.  */
 120 extern void *__nss_lookup_function (struct nss_action *ni, const char *fct_name);
 121 libc_hidden_proto (__nss_lookup_function)
 122
 123
 124 /* Called by NSCD to disable recursive calls and enable special handling
 125    when used in nscd.  */
 126 struct traced_file;
 127 extern void __nss_disable_nscd (void (*) (size_t, struct traced_file *));
 128
 129
 130 typedef int (*db_lookup_function) (struct nss_action **, const char *, const char *,
 131                                    void **);
 132 typedef enum nss_status (*setent_function) (int);
 133 typedef enum nss_status (*endent_function) (void);
 134 typedef enum nss_status (*getent_function) (void *, char *, size_t,
 135                                             int *, int *);
 136 typedef int (*getent_r_function) (void *, char *, size_t,
 137                                   void **result, int *);
 138
 139 extern void __nss_setent (const char *func_name,
 140                           db_lookup_function lookup_fct,
 141                           struct nss_action **nip, struct nss_action **startp,
 142                           struct nss_action **last_nip, int stayon,
 143                           int *stayon_tmp, int res)
 144      attribute_hidden;
 145 extern void __nss_endent (const char *func_name,
 146                           db_lookup_function lookup_fct,
 147                           struct nss_action **nip, struct nss_action **startp,
 148                           struct nss_action **last_nip, int res)
 149      attribute_hidden;
 150 extern int __nss_getent_r (const char *getent_func_name,
 151                            const char *setent_func_name,
 152                            db_lookup_function lookup_fct,
 153                            struct nss_action **nip, struct nss_action **startp,
 154                            struct nss_action **last_nip, int *stayon_tmp,
 155                            int res,
 156                            void *resbuf, char *buffer, size_t buflen,
 157                            void **result, int *h_errnop)
 158      attribute_hidden;
 159 extern void *__nss_getent (getent_r_function func,
 160                            void **resbuf, char **buffer, size_t buflen,
 161                            size_t *buffer_size, int *h_errnop)
 162      attribute_hidden;
 163 struct resolv_context;
 164 struct hostent;
 165 extern int __nss_hostname_digits_dots_context (struct resolv_context *,
 166                                                const char *name,
 167                                                struct hostent *resbuf,
 168                                                char **buffer,
 169                                                size_t *buffer_size,
 170                                                size_t buflen,
 171                                                struct hostent **result,
 172                                                enum nss_status *status, int af,
 173                                                int *h_errnop) attribute_hidden;
 174 extern int __nss_hostname_digits_dots (const char *name,
 175                                        struct hostent *resbuf, char **buffer,
 176                                        size_t *buffer_size, size_t buflen,
 177                                        struct hostent **result,
 178                                        enum nss_status *status, int af,
 179                                        int *h_errnop);
 180 libc_hidden_proto (__nss_hostname_digits_dots)
 181
 182 /* Maximum number of aliases we allow.  */
 183 #define MAX_NR_ALIASES  48
 184 #define MAX_NR_ADDRS    48
 185
 186 /* Prototypes for __nss_*_lookup2 functions.  */
 187 #define DEFINE_DATABASE(arg)                                                  \
 188   extern struct nss_action *__nss_##arg##_database attribute_hidden;                  \
 189   int __nss_##arg##_lookup2 (struct nss_action **, const char *,                      \
 190                              const char *, void **);                          \
 191   libc_hidden_proto (__nss_##arg##_lookup2)
 192 #include "databases.def"
 193 #undef DEFINE_DATABASE
 194
 195 #include <nss/nss_module.h>
 196 #include <nss/nss_action.h>
 197 #include <nss/nss_database.h>
 198
 199 #endif  /* nsswitch.h */