nscd/nscd-client.h

   1 /* Copyright (c) 1998-2019 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    <https://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 <string.h>
  28 #include <time.h>
  29 #include <sys/types.h>
  30 #include <atomic.h>
  31 #include <nscd-types.h>
  32 #include <sys/uio.h>
  33
  34
  35 /* Version number of the daemon interface */
  36 #define NSCD_VERSION 2
  37
  38 /* Path of the file where the PID of the running system is stored.  */
  39 #define _PATH_NSCDPID    "/var/run/nscd/nscd.pid"
  40
  41 /* Path for the Unix domain socket.  */
  42 #define _PATH_NSCDSOCKET "/var/run/nscd/socket"
  43
  44 /* Path for the configuration file.  */
  45 #define _PATH_NSCDCONF   "/etc/nscd.conf"
  46
  47 /* Maximum allowed length for the key.  */
  48 #define MAXKEYLEN 1024
  49
  50
  51 /* Available services.  */
  52 typedef enum
  53 {
  54   GETPWBYNAME,
  55   GETPWBYUID,
  56   GETGRBYNAME,
  57   GETGRBYGID,
  58   GETHOSTBYNAME,
  59   GETHOSTBYNAMEv6,
  60   GETHOSTBYADDR,
  61   GETHOSTBYADDRv6,
  62   SHUTDOWN,             /* Shut the server down.  */
  63   GETSTAT,              /* Get the server statistic.  */
  64   INVALIDATE,           /* Invalidate one special cache.  */
  65   GETFDPW,
  66   GETFDGR,
  67   GETFDHST,
  68   GETAI,
  69   INITGROUPS,
  70   GETSERVBYNAME,
  71   GETSERVBYPORT,
  72   GETFDSERV,
  73   GETNETGRENT,
  74   INNETGR,
  75   GETFDNETGR,
  76   LASTREQ
  77 } request_type;
  78
  79
  80 /* Header common to all requests */
  81 typedef struct
  82 {
  83   int32_t version;      /* Version number of the daemon interface.  */
  84   request_type type;    /* Service requested.  */
  85   int32_t key_len;      /* Key length.  */
  86 } request_header;
  87
  88
  89 /* Structure sent in reply to password query.  Note that this struct is
  90    sent also if the service is disabled or there is no record found.  */
  91 typedef struct
  92 {
  93   int32_t version;
  94   int32_t found;
  95   nscd_ssize_t pw_name_len;
  96   nscd_ssize_t pw_passwd_len;
  97   uid_t pw_uid;
  98   gid_t pw_gid;
  99   nscd_ssize_t pw_gecos_len;
 100   nscd_ssize_t pw_dir_len;
 101   nscd_ssize_t pw_shell_len;
 102 } pw_response_header;
 103
 104
 105 /* Structure sent in reply to group query.  Note that this struct is
 106    sent also if the service is disabled or there is no record found.  */
 107 typedef struct
 108 {
 109   int32_t version;
 110   int32_t found;
 111   nscd_ssize_t gr_name_len;
 112   nscd_ssize_t gr_passwd_len;
 113   gid_t gr_gid;
 114   nscd_ssize_t gr_mem_cnt;
 115 } gr_response_header;
 116
 117
 118 /* Structure sent in reply to host query.  Note that this struct is
 119    sent also if the service is disabled or there is no record found.  */
 120 typedef struct
 121 {
 122   int32_t version;
 123   int32_t found;
 124   nscd_ssize_t h_name_len;
 125   nscd_ssize_t h_aliases_cnt;
 126   int32_t h_addrtype;
 127   int32_t h_length;
 128   nscd_ssize_t h_addr_list_cnt;
 129   int32_t error;
 130 } hst_response_header;
 131
 132
 133 /* Structure sent in reply to addrinfo query.  Note that this struct is
 134    sent also if the service is disabled or there is no record found.  */
 135 typedef struct
 136 {
 137   int32_t version;
 138   int32_t found;
 139   nscd_ssize_t naddrs;
 140   nscd_ssize_t addrslen;
 141   nscd_ssize_t canonlen;
 142   int32_t error;
 143 } ai_response_header;
 144
 145 /* Structure filled in by __nscd_getai.  */
 146 struct nscd_ai_result
 147 {
 148   int naddrs;
 149   char *canon;
 150   uint8_t *family;
 151   char *addrs;
 152 };
 153
 154 /* Structure sent in reply to initgroups query.  Note that this struct is
 155    sent also if the service is disabled or there is no record found.  */
 156 typedef struct
 157 {
 158   int32_t version;
 159   int32_t found;
 160   nscd_ssize_t ngrps;
 161 } initgr_response_header;
 162
 163
 164 /* Structure sent in reply to services query.  Note that this struct is
 165    sent also if the service is disabled or there is no record found.  */
 166 typedef struct
 167 {
 168   int32_t version;
 169   int32_t found;
 170   nscd_ssize_t s_name_len;
 171   nscd_ssize_t s_proto_len;
 172   nscd_ssize_t s_aliases_cnt;
 173   int32_t s_port;
 174 } serv_response_header;
 175
 176
 177 /* Structure send in reply to netgroup query.  Note that this struct is
 178    sent also if the service is disabled or there is no record found.  */
 179 typedef struct
 180 {
 181   int32_t version;
 182   int32_t found;
 183   nscd_ssize_t nresults;
 184   nscd_ssize_t result_len;
 185 } netgroup_response_header;
 186
 187 typedef struct
 188 {
 189   int32_t version;
 190   int32_t found;
 191   int32_t result;
 192 } innetgroup_response_header;
 193
 194
 195 /* Type for offsets in data part of database.  */
 196 typedef uint32_t ref_t;
 197 /* Value for invalid/no reference.  */
 198 #define ENDREF  UINT32_MAX
 199
 200 /* Timestamp type.  */
 201 typedef uint64_t nscd_time_t;
 202
 203 /* Maximum timestamp.  */
 204 #define MAX_TIMEOUT_VALUE \
 205   (sizeof (time_t) == sizeof (long int) ? LONG_MAX : INT_MAX)
 206
 207 /* Alignment requirement of the beginning of the data region.  */
 208 #define ALIGN 16
 209
 210
 211 /* Head of record in data part of database.  */
 212 struct datahead
 213 {
 214   nscd_ssize_t allocsize;       /* Allocated Bytes.  */
 215   nscd_ssize_t recsize;         /* Size of the record.  */
 216   nscd_time_t timeout;          /* Time when this entry becomes invalid.  */
 217   uint8_t notfound;             /* Nonzero if data has not been found.  */
 218   uint8_t nreloads;             /* Reloads without use.  */
 219   uint8_t usable;               /* False if the entry must be ignored.  */
 220   uint8_t unused;               /* Unused.  */
 221   uint32_t ttl;                 /* TTL value used.  */
 222
 223   /* We need to have the following element aligned for the response
 224      header data types and their use in the 'struct dataset' types
 225      defined in the XXXcache.c files.  */
 226   union
 227   {
 228     pw_response_header pwdata;
 229     gr_response_header grdata;
 230     hst_response_header hstdata;
 231     ai_response_header aidata;
 232     initgr_response_header initgrdata;
 233     serv_response_header servdata;
 234     netgroup_response_header netgroupdata;
 235     innetgroup_response_header innetgroupdata;
 236     nscd_ssize_t align1;
 237     nscd_time_t align2;
 238   } data[0];
 239 };
 240
 241 static inline time_t
 242 datahead_init_common (struct datahead *head, nscd_ssize_t allocsize,
 243                       nscd_ssize_t recsize, uint32_t ttl)
 244 {
 245   /* Initialize so that we don't write out junk in uninitialized data to the
 246      cache.  */
 247   memset (head, 0, sizeof (*head));
 248
 249   head->allocsize = allocsize;
 250   head->recsize = recsize;
 251   head->usable = true;
 252
 253   head->ttl = ttl;
 254
 255   /* Compute and return the timeout time.  */
 256   return head->timeout = time (NULL) + ttl;
 257 }
 258
 259 static inline time_t
 260 datahead_init_pos (struct datahead *head, nscd_ssize_t allocsize,
 261                    nscd_ssize_t recsize, uint8_t nreloads, uint32_t ttl)
 262 {
 263   time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
 264
 265   head->notfound = false;
 266   head->nreloads = nreloads;
 267
 268   return ret;
 269 }
 270
 271 static inline time_t
 272 datahead_init_neg (struct datahead *head, nscd_ssize_t allocsize,
 273                    nscd_ssize_t recsize, uint32_t ttl)
 274 {
 275   time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
 276
 277   /* We don't need to touch nreloads here since it is set to our desired value
 278      (0) when we clear the structure.  */
 279   head->notfound = true;
 280
 281   return ret;
 282 }
 283
 284 /* Structure for one hash table entry.  */
 285 struct hashentry
 286 {
 287   request_type type:8;          /* Which type of dataset.  */
 288   bool first;                   /* True if this was the original key.  */
 289   nscd_ssize_t len;             /* Length of key.  */
 290   ref_t key;                    /* Pointer to key.  */
 291   int32_t owner;                /* If secure table, this is the owner.  */
 292   ref_t next;                   /* Next entry in this hash bucket list.  */
 293   ref_t packet;                 /* Records for the result.  */
 294   union
 295   {
 296     struct hashentry *dellist;  /* Next record to be deleted.  This can be a
 297                                    pointer since only nscd uses this field.  */
 298     ref_t *prevp;               /* Pointer to field containing forward
 299                                    reference.  */
 300   };
 301 };
 302
 303
 304 /* Current persistent database version.  */
 305 #define DB_VERSION      2
 306
 307 /* Maximum time allowed between updates of the timestamp.  */
 308 #define MAPPING_TIMEOUT (5 * 60)
 309
 310
 311 /* Used indices for the EXTRA_DATA element of 'database_pers_head'.
 312    Each database has its own indices.  */
 313 #define NSCD_HST_IDX_CONF_TIMESTAMP     0
 314
 315
 316 /* Header of persistent database file.  */
 317 struct database_pers_head
 318 {
 319   int32_t version;
 320   int32_t header_size;
 321   volatile int32_t gc_cycle;
 322   volatile int32_t nscd_certainly_running;
 323   volatile nscd_time_t timestamp;
 324   /* Room for extensions.  */
 325   volatile uint32_t extra_data[4];
 326
 327   nscd_ssize_t module;
 328   nscd_ssize_t data_size;
 329
 330   nscd_ssize_t first_free;      /* Offset of first free byte in data area.  */
 331
 332   nscd_ssize_t nentries;
 333   nscd_ssize_t maxnentries;
 334   nscd_ssize_t maxnsearched;
 335
 336   uint64_t poshit;
 337   uint64_t neghit;
 338   uint64_t posmiss;
 339   uint64_t negmiss;
 340
 341   uint64_t rdlockdelayed;
 342   uint64_t wrlockdelayed;
 343
 344   uint64_t addfailed;
 345
 346   ref_t array[0];
 347 };
 348
 349
 350 /* Mapped database record.  */
 351 struct mapped_database
 352 {
 353   const struct database_pers_head *head;
 354   const char *data;
 355   size_t mapsize;
 356   int counter;          /* > 0 indicates it is usable.  */
 357   size_t datasize;
 358 };
 359 #define NO_MAPPING ((struct mapped_database *) -1l)
 360
 361 struct locked_map_ptr
 362 {
 363   int lock;
 364   struct mapped_database *mapped;
 365 };
 366 #define libc_locked_map_ptr(class, name) class struct locked_map_ptr name
 367
 368 /* Try acquiring lock for mapptr, returns true if it succeeds, false
 369    if not.  */
 370 static inline bool
 371 __nscd_acquire_maplock (volatile struct locked_map_ptr *mapptr)
 372 {
 373   int cnt = 0;
 374   while (__builtin_expect (atomic_compare_and_exchange_val_acq (&mapptr->lock,
 375                                                                 1, 0) != 0, 0))
 376     {
 377       // XXX Best number of rounds?
 378       if (__glibc_unlikely (++cnt > 5))
 379         return false;
 380
 381       atomic_spin_nop ();
 382     }
 383
 384   return true;
 385 }
 386
 387
 388 /* Open socket connection to nscd server.  */
 389 extern int __nscd_open_socket (const char *key, size_t keylen,
 390                                request_type type, void *response,
 391                                size_t responselen) attribute_hidden;
 392
 393 /* Try to get a file descriptor for the shared meory segment
 394    containing the database.  */
 395 extern struct mapped_database *__nscd_get_mapping (request_type type,
 396                                                    const char *key,
 397                                                    struct mapped_database **mappedp) attribute_hidden;
 398
 399 /* Get reference of mapping.  */
 400 extern struct mapped_database *__nscd_get_map_ref (request_type type,
 401                                                    const char *name,
 402                                                    volatile struct locked_map_ptr *mapptr,
 403                                                    int *gc_cyclep)
 404   attribute_hidden;
 405
 406 /* Unmap database.  */
 407 extern void __nscd_unmap (struct mapped_database *mapped)
 408   attribute_hidden;
 409
 410 /* Drop reference of mapping.  */
 411 static int
 412 __attribute__ ((unused))
 413 __nscd_drop_map_ref (struct mapped_database *map, int *gc_cycle)
 414 {
 415   if (map != NO_MAPPING)
 416     {
 417       int now_cycle = map->head->gc_cycle;
 418       if (__glibc_unlikely (now_cycle != *gc_cycle))
 419         {
 420           /* We might have read inconsistent data.  */
 421           *gc_cycle = now_cycle;
 422           return -1;
 423         }
 424
 425       if (atomic_decrement_val (&map->counter) == 0)
 426         __nscd_unmap (map);
 427     }
 428
 429   return 0;
 430 }
 431
 432
 433 /* Search the mapped database.  */
 434 extern struct datahead *__nscd_cache_search (request_type type,
 435                                              const char *key,
 436                                              size_t keylen,
 437                                              const struct mapped_database *mapped,
 438                                              size_t datalen)
 439   attribute_hidden;
 440
 441 /* Wrappers around read, readv and write that only read/write less than LEN
 442    bytes on error or EOF.  */
 443 extern ssize_t __readall (int fd, void *buf, size_t len)
 444   attribute_hidden;
 445 extern ssize_t __readvall (int fd, const struct iovec *iov, int iovcnt)
 446   attribute_hidden;
 447 extern ssize_t writeall (int fd, const void *buf, size_t len)
 448   attribute_hidden;
 449
 450 /* Get netlink timestamp counter from mapped area or zero.  */
 451 extern uint32_t __nscd_get_nl_timestamp (void)
 452   attribute_hidden;
 453
 454 #endif /* nscd.h */