nss/nsswitch.h

   1 /* Copyright (C) 1996-2018 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    <http://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
  40 typedef struct service_library
  41 {
  42   /* Name of service (`files', `dns', `nis', ...).  */
  43   const char *name;
  44   /* Pointer to the loaded shared library.  */
  45   void *lib_handle;
  46   /* And the link to the next entry.  */
  47   struct service_library *next;
  48 } service_library;
  49
  50
  51 /* For mapping a function name to a function pointer.  It is known in
  52    nsswitch.c:nss_lookup_function that a string pointer for the lookup key
  53    is the first member.  */
  54 typedef struct
  55 {
  56   const char *fct_name;
  57   void *fct_ptr;
  58 } known_function;
  59
  60
  61 typedef struct service_user
  62 {
  63   /* And the link to the next entry.  */
  64   struct service_user *next;
  65   /* Action according to result.  */
  66   lookup_actions actions[5];
  67   /* Link to the underlying library object.  */
  68   service_library *library;
  69   /* Collection of known functions.  */
  70   void *known;
  71   /* Name of the service (`files', `dns', `nis', ...).  */
  72   char name[0];
  73 } service_user;
  74
  75 /* To access the action based on the status value use this macro.  */
  76 #define nss_next_action(ni, status) ((ni)->actions[2 + status])
  77
  78
  79 typedef struct name_database_entry
  80 {
  81   /* And the link to the next entry.  */
  82   struct name_database_entry *next;
  83   /* List of service to be used.  */
  84   service_user *service;
  85   /* Name of the database.  */
  86   char name[0];
  87 } name_database_entry;
  88
  89
  90 typedef struct name_database
  91 {
  92   /* List of all known databases.  */
  93   name_database_entry *entry;
  94   /* List of libraries with service implementation.  */
  95   service_library *library;
  96 } name_database;
  97
  98
  99 #ifdef USE_NSCD
 100 /* Indices into DATABASES in nsswitch.c and __NSS_DATABASE_CUSTOM.  */
 101 enum
 102   {
 103 # define DEFINE_DATABASE(arg) NSS_DBSIDX_##arg,
 104 # include "databases.def"
 105 # undef DEFINE_DATABASE
 106     NSS_DBSIDX_max
 107   };
 108
 109 /* Flags whether custom rules for database is set.  */
 110 extern bool __nss_database_custom[NSS_DBSIDX_max] attribute_hidden;
 111 #endif
 112
 113 /* Warning for NSS functions, which don't require dlopen if glibc
 114    was built with --enable-static-nss.  */
 115 #ifdef DO_STATIC_NSS
 116 # define nss_interface_function(name)
 117 #else
 118 # define nss_interface_function(name) static_link_warning (name)
 119 #endif
 120
 121
 122 /* Interface functions for NSS.  */
 123
 124 /* Get the data structure representing the specified database.
 125    If there is no configuration for this database in the file,
 126    parse a service list from DEFCONFIG and use that.  More
 127    than one function can use the database.  */
 128 extern int __nss_database_lookup (const char *database,
 129                                   const char *alternative_name,
 130                                   const char *defconfig, service_user **ni);
 131 libc_hidden_proto (__nss_database_lookup)
 132
 133 /* Put first function with name FCT_NAME for SERVICE in FCTP.  The
 134    position is remembered in NI.  The function returns a value < 0 if
 135    an error occurred or no such function exists.  */
 136 extern int __nss_lookup (service_user **ni, const char *fct_name,
 137                          const char *fct2_name, void **fctp);
 138 libc_hidden_proto (__nss_lookup)
 139
 140 /* Determine the next step in the lookup process according to the
 141    result STATUS of the call to the last function returned by
 142    `__nss_lookup' or `__nss_next'.  NI specifies the last function
 143    examined.  The function return a value > 0 if the process should
 144    stop with the last result of the last function call to be the
 145    result of the entire lookup.  The returned value is 0 if there is
 146    another function to use and < 0 if an error occurred.
 147
 148    If ALL_VALUES is nonzero, the return value will not be > 0 as long as
 149    there is a possibility the lookup process can ever use following
 150    services.  In other words, only if all four lookup results have
 151    the action RETURN associated the lookup process stops before the
 152    natural end.  */
 153 extern int __nss_next2 (service_user **ni, const char *fct_name,
 154                         const char *fct2_name, void **fctp, int status,
 155                         int all_values) attribute_hidden;
 156 libc_hidden_proto (__nss_next2)
 157 extern int __nss_next (service_user **ni, const char *fct_name, void **fctp,
 158                        int status, int all_values);
 159
 160 /* Search for the service described in NI for a function named FCT_NAME
 161    and return a pointer to this function if successful.  */
 162 extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
 163 libc_hidden_proto (__nss_lookup_function)
 164
 165
 166 /* Called by NSCD to disable recursive calls and enable special handling
 167    when used in nscd.  */
 168 struct traced_file;
 169 extern void __nss_disable_nscd (void (*) (size_t, struct traced_file *));
 170
 171
 172 typedef int (*db_lookup_function) (service_user **, const char *, const char *,
 173                                    void **);
 174 typedef enum nss_status (*setent_function) (int);
 175 typedef enum nss_status (*endent_function) (void);
 176 typedef enum nss_status (*getent_function) (void *, char *, size_t,
 177                                             int *, int *);
 178 typedef int (*getent_r_function) (void *, char *, size_t,
 179                                   void **result, int *);
 180
 181 extern void __nss_setent (const char *func_name,
 182                           db_lookup_function lookup_fct,
 183                           service_user **nip, service_user **startp,
 184                           service_user **last_nip, int stayon,
 185                           int *stayon_tmp, int res)
 186      attribute_hidden;
 187 extern void __nss_endent (const char *func_name,
 188                           db_lookup_function lookup_fct,
 189                           service_user **nip, service_user **startp,
 190                           service_user **last_nip, int res)
 191      attribute_hidden;
 192 extern int __nss_getent_r (const char *getent_func_name,
 193                            const char *setent_func_name,
 194                            db_lookup_function lookup_fct,
 195                            service_user **nip, service_user **startp,
 196                            service_user **last_nip, int *stayon_tmp,
 197                            int res,
 198                            void *resbuf, char *buffer, size_t buflen,
 199                            void **result, int *h_errnop)
 200      attribute_hidden;
 201 extern void *__nss_getent (getent_r_function func,
 202                            void **resbuf, char **buffer, size_t buflen,
 203                            size_t *buffer_size, int *h_errnop)
 204      attribute_hidden;
 205 struct resolv_context;
 206 struct hostent;
 207 extern int __nss_hostname_digits_dots_context (struct resolv_context *,
 208                                                const char *name,
 209                                                struct hostent *resbuf,
 210                                                char **buffer,
 211                                                size_t *buffer_size,
 212                                                size_t buflen,
 213                                                struct hostent **result,
 214                                                enum nss_status *status, int af,
 215                                                int *h_errnop) attribute_hidden;
 216 extern int __nss_hostname_digits_dots (const char *name,
 217                                        struct hostent *resbuf, char **buffer,
 218                                        size_t *buffer_size, size_t buflen,
 219                                        struct hostent **result,
 220                                        enum nss_status *status, int af,
 221                                        int *h_errnop);
 222 libc_hidden_proto (__nss_hostname_digits_dots)
 223
 224 /* Maximum number of aliases we allow.  */
 225 #define MAX_NR_ALIASES  48
 226 #define MAX_NR_ADDRS    48
 227
 228 /* Prototypes for __nss_*_lookup2 functions.  */
 229 #define DEFINE_DATABASE(arg)                                                  \
 230   extern service_user *__nss_##arg##_database attribute_hidden;               \
 231   int __nss_##arg##_lookup2 (service_user **, const char *,                   \
 232                              const char *, void **);                          \
 233   libc_hidden_proto (__nss_##arg##_lookup2)
 234 #include "databases.def"
 235 #undef DEFINE_DATABASE
 236
 237 #endif  /* nsswitch.h */