nss/nsswitch.h

   1 /* Copyright (C) 1996-2017 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 /* Indices into DATABASES in nsswitch.c and __NSS_DATABASE_CUSTOM.  */
 100 enum
 101   {
 102 #define DEFINE_DATABASE(arg) NSS_DBSIDX_##arg,
 103 #include "databases.def"
 104 #undef DEFINE_DATABASE
 105     NSS_DBSIDX_max
 106   };
 107
 108 /* Flags whether custom rules for database is set.  */
 109 extern bool __nss_database_custom[NSS_DBSIDX_max];
 110
 111 /* Warning for NSS functions, which don't require dlopen if glibc
 112    was built with --enable-static-nss.  */
 113 #ifdef DO_STATIC_NSS
 114 # define nss_interface_function(name)
 115 #else
 116 # define nss_interface_function(name) static_link_warning (name)
 117 #endif
 118
 119
 120 /* Interface functions for NSS.  */
 121
 122 /* Get the data structure representing the specified database.
 123    If there is no configuration for this database in the file,
 124    parse a service list from DEFCONFIG and use that.  More
 125    than one function can use the database.  */
 126 extern int __nss_database_lookup (const char *database,
 127                                   const char *alternative_name,
 128                                   const char *defconfig, service_user **ni);
 129 libc_hidden_proto (__nss_database_lookup)
 130
 131 /* Put first function with name FCT_NAME for SERVICE in FCTP.  The
 132    position is remembered in NI.  The function returns a value < 0 if
 133    an error occurred or no such function exists.  */
 134 extern int __nss_lookup (service_user **ni, const char *fct_name,
 135                          const char *fct2_name, void **fctp);
 136 libc_hidden_proto (__nss_lookup)
 137
 138 /* Determine the next step in the lookup process according to the
 139    result STATUS of the call to the last function returned by
 140    `__nss_lookup' or `__nss_next'.  NI specifies the last function
 141    examined.  The function return a value > 0 if the process should
 142    stop with the last result of the last function call to be the
 143    result of the entire lookup.  The returned value is 0 if there is
 144    another function to use and < 0 if an error occurred.
 145
 146    If ALL_VALUES is nonzero, the return value will not be > 0 as long as
 147    there is a possibility the lookup process can ever use following
 148    services.  In other words, only if all four lookup results have
 149    the action RETURN associated the lookup process stops before the
 150    natural end.  */
 151 extern int __nss_next2 (service_user **ni, const char *fct_name,
 152                         const char *fct2_name, void **fctp, int status,
 153                         int all_values) attribute_hidden;
 154 libc_hidden_proto (__nss_next2)
 155 extern int __nss_next (service_user **ni, const char *fct_name, void **fctp,
 156                        int status, int all_values);
 157
 158 /* Search for the service described in NI for a function named FCT_NAME
 159    and return a pointer to this function if successful.  */
 160 extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
 161 libc_hidden_proto (__nss_lookup_function)
 162
 163
 164 /* Called by NSCD to disable recursive calls and enable special handling
 165    when used in nscd.  */
 166 struct traced_file;
 167 extern void __nss_disable_nscd (void (*) (size_t, struct traced_file *));
 168
 169
 170 typedef int (*db_lookup_function) (service_user **, const char *, const char *,
 171                                    void **)
 172      internal_function;
 173 typedef enum nss_status (*setent_function) (int);
 174 typedef enum nss_status (*endent_function) (void);
 175 typedef enum nss_status (*getent_function) (void *, char *, size_t,
 176                                             int *, int *);
 177 typedef int (*getent_r_function) (void *, char *, size_t,
 178                                   void **result, int *);
 179
 180 extern void __nss_setent (const char *func_name,
 181                           db_lookup_function lookup_fct,
 182                           service_user **nip, service_user **startp,
 183                           service_user **last_nip, int stayon,
 184                           int *stayon_tmp, int res);
 185 extern void __nss_endent (const char *func_name,
 186                           db_lookup_function lookup_fct,
 187                           service_user **nip, service_user **startp,
 188                           service_user **last_nip, int res);
 189 extern int __nss_getent_r (const char *getent_func_name,
 190                            const char *setent_func_name,
 191                            db_lookup_function lookup_fct,
 192                            service_user **nip, service_user **startp,
 193                            service_user **last_nip, int *stayon_tmp,
 194                            int res,
 195                            void *resbuf, char *buffer, size_t buflen,
 196                            void **result, int *h_errnop);
 197 extern void *__nss_getent (getent_r_function func,
 198                            void **resbuf, char **buffer, size_t buflen,
 199                            size_t *buffer_size, int *h_errnop);
 200 struct hostent;
 201 extern int __nss_hostname_digits_dots (const char *name,
 202                                        struct hostent *resbuf, char **buffer,
 203                                        size_t *buffer_size, size_t buflen,
 204                                        struct hostent **result,
 205                                        enum nss_status *status, int af,
 206                                        int *h_errnop);
 207 libc_hidden_proto (__nss_hostname_digits_dots)
 208
 209 /* Maximum number of aliases we allow.  */
 210 #define MAX_NR_ALIASES  48
 211 #define MAX_NR_ADDRS    48
 212
 213 #endif  /* nsswitch.h */