nscd/nscd-client.h

   1 /* Copyright (c) 1998-2012 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Thorsten Kukuk <kukuk@suse.de>, 1998.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /* This file defines everything that client code should need to
  20    know to talk to the nscd daemon.  */
  21
  22 #ifndef _NSCD_CLIENT_H
  23 #define _NSCD_CLIENT_H  1
  24
  25 #include <stdbool.h>
  26 #include <stdint.h>
  27 #include <sys/types.h>
  28 #include <atomic.h>
  29 #include <nscd-types.h>
  30 #include <sys/uio.h>
  31
  32
  33 /* Version number of the daemon interface */
  34 #define NSCD_VERSION 2
  35
  36 /* Path of the file where the PID of the running system is stored.  */
  37 #define _PATH_NSCDPID    "/var/run/nscd/nscd.pid"
  38
  39 /* Path for the Unix domain socket.  */
  40 #define _PATH_NSCDSOCKET "/var/run/nscd/socket"
  41
  42 /* Path for the configuration file.  */
  43 #define _PATH_NSCDCONF   "/etc/nscd.conf"
  44
  45 /* Maximum allowed length for the key.  */
  46 #define MAXKEYLEN 1024
  47
  48
  49 /* Available services.  */
  50 typedef enum
  51 {
  52   GETPWBYNAME,
  53   GETPWBYUID,
  54   GETGRBYNAME,
  55   GETGRBYGID,
  56   GETHOSTBYNAME,
  57   GETHOSTBYNAMEv6,
  58   GETHOSTBYADDR,
  59   GETHOSTBYADDRv6,
  60   SHUTDOWN,             /* Shut the server down.  */
  61   GETSTAT,              /* Get the server statistic.  */
  62   INVALIDATE,           /* Invalidate one special cache.  */
  63   GETFDPW,
  64   GETFDGR,
  65   GETFDHST,
  66   GETAI,
  67   INITGROUPS,
  68   GETSERVBYNAME,
  69   GETSERVBYPORT,
  70   GETFDSERV,
  71   GETNETGRENT,
  72   INNETGR,
  73   GETFDNETGR,
  74   LASTREQ
  75 } request_type;
  76
  77
  78 /* Header common to all requests */
  79 typedef struct
  80 {
  81   int32_t version;      /* Version number of the daemon interface.  */
  82   request_type type;    /* Service requested.  */
  83   int32_t key_len;      /* Key length.  */
  84 } request_header;
  85
  86
  87 /* Structure sent in reply to password query.  Note that this struct is
  88    sent also if the service is disabled or there is no record found.  */
  89 typedef struct
  90 {
  91   int32_t version;
  92   int32_t found;
  93   nscd_ssize_t pw_name_len;
  94   nscd_ssize_t pw_passwd_len;
  95   uid_t pw_uid;
  96   gid_t pw_gid;
  97   nscd_ssize_t pw_gecos_len;
  98   nscd_ssize_t pw_dir_len;
  99   nscd_ssize_t pw_shell_len;
 100 } pw_response_header;
 101
 102
 103 /* Structure sent in reply to group query.  Note that this struct is
 104    sent also if the service is disabled or there is no record found.  */
 105 typedef struct
 106 {
 107   int32_t version;
 108   int32_t found;
 109   nscd_ssize_t gr_name_len;
 110   nscd_ssize_t gr_passwd_len;
 111   gid_t gr_gid;
 112   nscd_ssize_t gr_mem_cnt;
 113 } gr_response_header;
 114
 115
 116 /* Structure sent in reply to host query.  Note that this struct is
 117    sent also if the service is disabled or there is no record found.  */
 118 typedef struct
 119 {
 120   int32_t version;
 121   int32_t found;
 122   nscd_ssize_t h_name_len;
 123   nscd_ssize_t h_aliases_cnt;
 124   int32_t h_addrtype;
 125   int32_t h_length;
 126   nscd_ssize_t h_addr_list_cnt;
 127   int32_t error;
 128 } hst_response_header;
 129
 130
 131 /* Structure sent in reply to addrinfo query.  Note that this struct is
 132    sent also if the service is disabled or there is no record found.  */
 133 typedef struct
 134 {
 135   int32_t version;
 136   int32_t found;
 137   nscd_ssize_t naddrs;
 138   nscd_ssize_t addrslen;
 139   nscd_ssize_t canonlen;
 140   int32_t error;
 141 } ai_response_header;
 142
 143 /* Structure filled in by __nscd_getai.  */
 144 struct nscd_ai_result
 145 {
 146   int naddrs;
 147   char *canon;
 148   uint8_t *family;
 149   char *addrs;
 150 };
 151
 152 /* Structure sent in reply to initgroups query.  Note that this struct is
 153    sent also if the service is disabled or there is no record found.  */
 154 typedef struct
 155 {
 156   int32_t version;
 157   int32_t found;
 158   nscd_ssize_t ngrps;
 159 } initgr_response_header;
 160
 161
 162 /* Structure sent in reply to services query.  Note that this struct is
 163    sent also if the service is disabled or there is no record found.  */
 164 typedef struct
 165 {
 166   int32_t version;
 167   int32_t found;
 168   nscd_ssize_t s_name_len;
 169   nscd_ssize_t s_proto_len;
 170   nscd_ssize_t s_aliases_cnt;
 171   int32_t s_port;
 172 } serv_response_header;
 173
 174
 175 /* Structure send in reply to netgroup query.  Note that this struct is
 176    sent also if the service is disabled or there is no record found.  */
 177 typedef struct
 178 {
 179   int32_t version;
 180   int32_t found;
 181   nscd_ssize_t nresults;
 182   nscd_ssize_t result_len;
 183 } netgroup_response_header;
 184
 185 typedef struct
 186 {
 187   int32_t version;
 188   int32_t found;
 189   int32_t result;
 190 } innetgroup_response_header;
 191
 192
 193 /* Type for offsets in data part of database.  */
 194 typedef uint32_t ref_t;
 195 /* Value for invalid/no reference.  */
 196 #define ENDREF  UINT32_MAX
 197
 198 /* Timestamp type.  */
 199 typedef uint64_t nscd_time_t;
 200
 201 /* Maximum timestamp.  */
 202 #define MAX_TIMEOUT_VALUE \
 203   (sizeof (time_t) == sizeof (long int) ? LONG_MAX : INT_MAX)
 204
 205 /* Alignment requirement of the beginning of the data region.  */
 206 #define ALIGN 16
 207
 208
 209 /* Head of record in data part of database.  */
 210 struct datahead
 211 {
 212   nscd_ssize_t allocsize;       /* Allocated Bytes.  */
 213   nscd_ssize_t recsize;         /* Size of the record.  */
 214   nscd_time_t timeout;          /* Time when this entry becomes invalid.  */
 215   uint8_t notfound;             /* Nonzero if data has not been found.  */
 216   uint8_t nreloads;             /* Reloads without use.  */
 217   uint8_t usable;               /* False if the entry must be ignored.  */
 218   uint8_t unused;               /* Unused.  */
 219   uint32_t ttl;                 /* TTL value used.  */
 220
 221   /* We need to have the following element aligned for the response
 222      header data types and their use in the 'struct dataset' types
 223      defined in the XXXcache.c files.  */
 224   union
 225   {
 226     pw_response_header pwdata;
 227     gr_response_header grdata;
 228     hst_response_header hstdata;
 229     ai_response_header aidata;
 230     initgr_response_header initgrdata;
 231     serv_response_header servdata;
 232     netgroup_response_header netgroupdata;
 233     innetgroup_response_header innetgroupdata;
 234     nscd_ssize_t align1;
 235     nscd_time_t align2;
 236   } data[0];
 237 };
 238
 239
 240 /* Structure for one hash table entry.  */
 241 struct hashentry
 242 {
 243   request_type type:8;          /* Which type of dataset.  */
 244   bool first;                   /* True if this was the original key.  */
 245   nscd_ssize_t len;             /* Length of key.  */
 246   ref_t key;                    /* Pointer to key.  */
 247   int32_t owner;                /* If secure table, this is the owner.  */
 248   ref_t next;                   /* Next entry in this hash bucket list.  */
 249   ref_t packet;                 /* Records for the result.  */
 250   union
 251   {
 252     struct hashentry *dellist;  /* Next record to be deleted.  This can be a
 253                                    pointer since only nscd uses this field.  */
 254     ref_t *prevp;               /* Pointer to field containing forward
 255                                    reference.  */
 256   };
 257 };
 258
 259
 260 /* Current persistent database version.  */
 261 #define DB_VERSION      2
 262
 263 /* Maximum time allowed between updates of the timestamp.  */
 264 #define MAPPING_TIMEOUT (5 * 60)
 265
 266
 267 /* Used indices for the EXTRA_DATA element of 'database_pers_head'.
 268    Each database has its own indices.  */
 269 #define NSCD_HST_IDX_CONF_TIMESTAMP     0
 270
 271
 272 /* Header of persistent database file.  */
 273 struct database_pers_head
 274 {
 275   int32_t version;
 276   int32_t header_size;
 277   volatile int32_t gc_cycle;
 278   volatile int32_t nscd_certainly_running;
 279   volatile nscd_time_t timestamp;
 280   /* Room for extensions.  */
 281   volatile uint32_t extra_data[4];
 282
 283   nscd_ssize_t module;
 284   nscd_ssize_t data_size;
 285
 286   nscd_ssize_t first_free;      /* Offset of first free byte in data area.  */
 287
 288   nscd_ssize_t nentries;
 289   nscd_ssize_t maxnentries;
 290   nscd_ssize_t maxnsearched;
 291
 292   uint64_t poshit;
 293   uint64_t neghit;
 294   uint64_t posmiss;
 295   uint64_t negmiss;
 296
 297   uint64_t rdlockdelayed;
 298   uint64_t wrlockdelayed;
 299
 300   uint64_t addfailed;
 301
 302   ref_t array[0];
 303 };
 304
 305
 306 /* Mapped database record.  */
 307 struct mapped_database
 308 {
 309   const struct database_pers_head *head;
 310   const char *data;
 311   size_t mapsize;
 312   int counter;          /* > 0 indicates it is usable.  */
 313   size_t datasize;
 314 };
 315 #define NO_MAPPING ((struct mapped_database *) -1l)
 316
 317 struct locked_map_ptr
 318 {
 319   int lock;
 320   struct mapped_database *mapped;
 321 };
 322 #define libc_locked_map_ptr(class, name) class struct locked_map_ptr name
 323
 324 /* Try acquiring lock for mapptr, returns true if it succeeds, false
 325    if not.  */
 326 static inline bool
 327 __nscd_acquire_maplock (volatile struct locked_map_ptr *mapptr)
 328 {
 329   int cnt = 0;
 330   while (__builtin_expect (atomic_compare_and_exchange_val_acq (&mapptr->lock,
 331                                                                 1, 0) != 0, 0))
 332     {
 333       // XXX Best number of rounds?
 334       if (__builtin_expect (++cnt > 5, 0))
 335         return false;
 336
 337       atomic_delay ();
 338     }
 339
 340   return true;
 341 }
 342
 343
 344 /* Open socket connection to nscd server.  */
 345 extern int __nscd_open_socket (const char *key, size_t keylen,
 346                                request_type type, void *response,
 347                                size_t responselen) attribute_hidden;
 348
 349 /* Try to get a file descriptor for the shared meory segment
 350    containing the database.  */
 351 extern struct mapped_database *__nscd_get_mapping (request_type type,
 352                                                    const char *key,
 353                                                    struct mapped_database **mappedp) attribute_hidden;
 354
 355 /* Get reference of mapping.  */
 356 extern struct mapped_database *__nscd_get_map_ref (request_type type,
 357                                                    const char *name,
 358                                                    volatile struct locked_map_ptr *mapptr,
 359                                                    int *gc_cyclep);
 360
 361 /* Unmap database.  */
 362 extern void __nscd_unmap (struct mapped_database *mapped);
 363
 364 /* Drop reference of mapping.  */
 365 static inline int __nscd_drop_map_ref (struct mapped_database *map,
 366                                        int *gc_cycle)
 367 {
 368   if (map != NO_MAPPING)
 369     {
 370       int now_cycle = map->head->gc_cycle;
 371       if (__builtin_expect (now_cycle != *gc_cycle, 0))
 372         {
 373           /* We might have read inconsistent data.  */
 374           *gc_cycle = now_cycle;
 375           return -1;
 376         }
 377
 378       if (atomic_decrement_val (&map->counter) == 0)
 379         __nscd_unmap (map);
 380     }
 381
 382   return 0;
 383 }
 384
 385
 386 /* Search the mapped database.  */
 387 extern struct datahead *__nscd_cache_search (request_type type,
 388                                              const char *key,
 389                                              size_t keylen,
 390                                              const struct mapped_database *mapped,
 391                                              size_t datalen);
 392
 393 /* Wrappers around read, readv and write that only read/write less than LEN
 394    bytes on error or EOF.  */
 395 extern ssize_t __readall (int fd, void *buf, size_t len)
 396   attribute_hidden;
 397 extern ssize_t __readvall (int fd, const struct iovec *iov, int iovcnt)
 398   attribute_hidden;
 399 extern ssize_t writeall (int fd, const void *buf, size_t len)
 400   attribute_hidden;
 401 extern ssize_t sendfileall (int tofd, int fromfd, off_t off, size_t len)
 402   attribute_hidden;
 403
 404 /* Get netlink timestamp counter from mapped area or zero.  */
 405 extern uint32_t __nscd_get_nl_timestamp (void);
 406
 407 #endif /* nscd.h */