1/* Copyright (c) 1998-2024 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/* This file defines everything that client code should need to
19 know to talk to the nscd daemon. */
20
21#ifndef _NSCD_CLIENT_H
22#define _NSCD_CLIENT_H 1
23
24#include <stdbool.h>
25#include <stdint.h>
26#include <string.h>
27#include <time.h>
28#include <sys/types.h>
29#include <atomic.h>
30#include <nscd-types.h>
31#include <sys/uio.h>
32
33
34/* Version number of the daemon interface */
35#define NSCD_VERSION 2
36
37/* Path of the file where the PID of the running system is stored. */
38#define _PATH_NSCDPID "/var/run/nscd/nscd.pid"
39
40/* Path for the Unix domain socket. */
41#define _PATH_NSCDSOCKET "/var/run/nscd/socket"
42
43/* Path for the configuration file. */
44#define _PATH_NSCDCONF "/etc/nscd.conf"
45
46/* Maximum allowed length for the key. */
47#define MAXKEYLEN 1024
48
49
50/* Available services. */
51typedef enum
52{
53 GETPWBYNAME,
54 GETPWBYUID,
55 GETGRBYNAME,
56 GETGRBYGID,
57 GETHOSTBYNAME,
58 GETHOSTBYNAMEv6,
59 GETHOSTBYADDR,
60 GETHOSTBYADDRv6,
61 SHUTDOWN, /* Shut the server down. */
62 GETSTAT, /* Get the server statistic. */
63 INVALIDATE, /* Invalidate one special cache. */
64 GETFDPW,
65 GETFDGR,
66 GETFDHST,
67 GETAI,
68 INITGROUPS,
69 GETSERVBYNAME,
70 GETSERVBYPORT,
71 GETFDSERV,
72 GETNETGRENT,
73 INNETGR,
74 GETFDNETGR,
75 LASTREQ
76} request_type;
77
78
79/* Header common to all requests */
80typedef struct
81{
82 int32_t version; /* Version number of the daemon interface. */
83 request_type type; /* Service requested. */
84 int32_t key_len; /* Key length. */
85} request_header;
86
87
88/* Structure sent in reply to password query. Note that this struct is
89 sent also if the service is disabled or there is no record found. */
90typedef struct
91{
92 int32_t version;
93 int32_t found;
94 nscd_ssize_t pw_name_len;
95 nscd_ssize_t pw_passwd_len;
96 uid_t pw_uid;
97 gid_t pw_gid;
98 nscd_ssize_t pw_gecos_len;
99 nscd_ssize_t pw_dir_len;
100 nscd_ssize_t pw_shell_len;
101} pw_response_header;
102
103
104/* Structure sent in reply to group query. Note that this struct is
105 sent also if the service is disabled or there is no record found. */
106typedef struct
107{
108 int32_t version;
109 int32_t found;
110 nscd_ssize_t gr_name_len;
111 nscd_ssize_t gr_passwd_len;
112 gid_t gr_gid;
113 nscd_ssize_t gr_mem_cnt;
114} gr_response_header;
115
116
117/* Structure sent in reply to host query. Note that this struct is
118 sent also if the service is disabled or there is no record found. */
119typedef struct
120{
121 int32_t version;
122 int32_t found;
123 nscd_ssize_t h_name_len;
124 nscd_ssize_t h_aliases_cnt;
125 int32_t h_addrtype;
126 int32_t h_length;
127 nscd_ssize_t h_addr_list_cnt;
128 int32_t error;
129} hst_response_header;
130
131
132/* Structure sent in reply to addrinfo query. Note that this struct is
133 sent also if the service is disabled or there is no record found. */
134typedef struct
135{
136 int32_t version;
137 int32_t found;
138 nscd_ssize_t naddrs;
139 nscd_ssize_t addrslen;
140 nscd_ssize_t canonlen;
141 int32_t error;
142} ai_response_header;
143
144/* Structure filled in by __nscd_getai. */
145struct nscd_ai_result
146{
147 int naddrs;
148 char *canon;
149 uint8_t *family;
150 char *addrs;
151};
152
153/* Structure sent in reply to initgroups query. Note that this struct is
154 sent also if the service is disabled or there is no record found. */
155typedef struct
156{
157 int32_t version;
158 int32_t found;
159 nscd_ssize_t ngrps;
160} initgr_response_header;
161
162
163/* Structure sent in reply to services query. Note that this struct is
164 sent also if the service is disabled or there is no record found. */
165typedef struct
166{
167 int32_t version;
168 int32_t found;
169 nscd_ssize_t s_name_len;
170 nscd_ssize_t s_proto_len;
171 nscd_ssize_t s_aliases_cnt;
172 int32_t s_port;
173} serv_response_header;
174
175
176/* Structure send in reply to netgroup query. Note that this struct is
177 sent also if the service is disabled or there is no record found. */
178typedef struct
179{
180 int32_t version;
181 int32_t found;
182 nscd_ssize_t nresults;
183 nscd_ssize_t result_len;
184} netgroup_response_header;
185
186typedef struct
187{
188 int32_t version;
189 int32_t found;
190 int32_t result;
191} innetgroup_response_header;
192
193
194/* Type for offsets in data part of database. */
195typedef uint32_t ref_t;
196/* Value for invalid/no reference. */
197#define ENDREF UINT32_MAX
198
199/* Timestamp type. */
200typedef uint64_t nscd_time_t;
201
202/* Maximum timestamp. */
203#define MAX_TIMEOUT_VALUE \
204 (sizeof (time_t) == sizeof (long int) ? LONG_MAX : INT_MAX)
205
206/* Alignment requirement of the beginning of the data region. */
207#define ALIGN 16
208
209
210/* Head of record in data part of database. */
211struct datahead
212{
213 nscd_ssize_t allocsize; /* Allocated Bytes. */
214 nscd_ssize_t recsize; /* Size of the record. */
215 nscd_time_t timeout; /* Time when this entry becomes invalid. */
216 uint8_t notfound; /* Nonzero if data has not been found. */
217 uint8_t nreloads; /* Reloads without use. */
218 uint8_t usable; /* False if the entry must be ignored. */
219 uint8_t unused; /* Unused. */
220 uint32_t ttl; /* TTL value used. */
221
222 /* We need to have the following element aligned for the response
223 header data types and their use in the 'struct dataset' types
224 defined in the XXXcache.c files. */
225 union
226 {
227 pw_response_header pwdata;
228 gr_response_header grdata;
229 hst_response_header hstdata;
230 ai_response_header aidata;
231 initgr_response_header initgrdata;
232 serv_response_header servdata;
233 netgroup_response_header netgroupdata;
234 innetgroup_response_header innetgroupdata;
235 nscd_ssize_t align1;
236 nscd_time_t align2;
237 } data[0];
238};
239
240static inline time_t
241datahead_init_common (struct datahead *head, nscd_ssize_t allocsize,
242 nscd_ssize_t recsize, uint32_t ttl)
243{
244 /* Initialize so that we don't write out junk in uninitialized data to the
245 cache. */
246 memset (s: head, c: 0, n: sizeof (*head));
247
248 head->allocsize = allocsize;
249 head->recsize = recsize;
250 head->usable = true;
251
252 head->ttl = ttl;
253
254 /* Compute and return the timeout time. */
255 return head->timeout = time (NULL) + ttl;
256}
257
258static inline time_t
259datahead_init_pos (struct datahead *head, nscd_ssize_t allocsize,
260 nscd_ssize_t recsize, uint8_t nreloads, uint32_t ttl)
261{
262 time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
263
264 head->notfound = false;
265 head->nreloads = nreloads;
266
267 return ret;
268}
269
270static inline time_t
271datahead_init_neg (struct datahead *head, nscd_ssize_t allocsize,
272 nscd_ssize_t recsize, uint32_t ttl)
273{
274 time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
275
276 /* We don't need to touch nreloads here since it is set to our desired value
277 (0) when we clear the structure. */
278 head->notfound = true;
279
280 return ret;
281}
282
283/* Structure for one hash table entry. */
284struct hashentry
285{
286 request_type type:8; /* Which type of dataset. */
287 bool first; /* True if this was the original key. */
288 nscd_ssize_t len; /* Length of key. */
289 ref_t key; /* Pointer to key. */
290 int32_t owner; /* If secure table, this is the owner. */
291 ref_t next; /* Next entry in this hash bucket list. */
292 ref_t packet; /* Records for the result. */
293 union
294 {
295 struct hashentry *dellist; /* Next record to be deleted. This can be a
296 pointer since only nscd uses this field. */
297 ref_t *prevp; /* Pointer to field containing forward
298 reference. */
299 };
300};
301
302
303/* Current persistent database version. */
304#define DB_VERSION 2
305
306/* Maximum time allowed between updates of the timestamp. */
307#define MAPPING_TIMEOUT (5 * 60)
308
309
310/* Used indices for the EXTRA_DATA element of 'database_pers_head'.
311 Each database has its own indices. */
312#define NSCD_HST_IDX_CONF_TIMESTAMP 0
313
314
315/* Header of persistent database file. */
316struct database_pers_head
317{
318 int32_t version;
319 int32_t header_size;
320 volatile int32_t gc_cycle;
321 volatile int32_t nscd_certainly_running;
322 volatile nscd_time_t timestamp;
323 /* Room for extensions. */
324 volatile uint32_t extra_data[4];
325
326 nscd_ssize_t module;
327 nscd_ssize_t data_size;
328
329 nscd_ssize_t first_free; /* Offset of first free byte in data area. */
330
331 nscd_ssize_t nentries;
332 nscd_ssize_t maxnentries;
333 nscd_ssize_t maxnsearched;
334
335 uint64_t poshit;
336 uint64_t neghit;
337 uint64_t posmiss;
338 uint64_t negmiss;
339
340 uint64_t rdlockdelayed;
341 uint64_t wrlockdelayed;
342
343 uint64_t addfailed;
344
345 ref_t array[0];
346};
347
348
349/* Mapped database record. */
350struct mapped_database
351{
352 const struct database_pers_head *head;
353 const char *data;
354 size_t mapsize;
355 int counter; /* > 0 indicates it is usable. */
356 size_t datasize;
357};
358#define NO_MAPPING ((struct mapped_database *) -1l)
359
360struct locked_map_ptr
361{
362 int lock;
363 struct mapped_database *mapped;
364};
365#define libc_locked_map_ptr(class, name) class struct locked_map_ptr name
366
367/* Try acquiring lock for mapptr, returns true if it succeeds, false
368 if not. */
369static inline bool
370__nscd_acquire_maplock (volatile struct locked_map_ptr *mapptr)
371{
372 int cnt = 0;
373 while (__builtin_expect (atomic_compare_and_exchange_val_acq (&mapptr->lock,
374 1, 0) != 0, 0))
375 {
376 // XXX Best number of rounds?
377 if (__glibc_unlikely (++cnt > 5))
378 return false;
379
380 atomic_spin_nop ();
381 }
382
383 return true;
384}
385
386
387/* Open socket connection to nscd server. */
388extern int __nscd_open_socket (const char *key, size_t keylen,
389 request_type type, void *response,
390 size_t responselen) attribute_hidden;
391
392/* Try to get a file descriptor for the shared memory segment
393 containing the database. */
394extern struct mapped_database *__nscd_get_mapping (request_type type,
395 const char *key,
396 struct mapped_database **mappedp) attribute_hidden;
397
398/* Get reference of mapping. */
399extern struct mapped_database *__nscd_get_map_ref (request_type type,
400 const char *name,
401 volatile struct locked_map_ptr *mapptr,
402 int *gc_cyclep)
403 attribute_hidden;
404
405/* Unmap database. */
406extern void __nscd_unmap (struct mapped_database *mapped)
407 attribute_hidden;
408
409/* Drop reference of mapping. */
410static int
411__attribute__ ((unused))
412__nscd_drop_map_ref (struct mapped_database *map, int *gc_cycle)
413{
414 if (map != NO_MAPPING)
415 {
416 int now_cycle = map->head->gc_cycle;
417 if (__glibc_unlikely (now_cycle != *gc_cycle))
418 {
419 /* We might have read inconsistent data. */
420 *gc_cycle = now_cycle;
421 return -1;
422 }
423
424 if (atomic_fetch_add_relaxed (&map->counter, -1) == 1)
425 __nscd_unmap (mapped: map);
426 }
427
428 return 0;
429}
430
431
432/* Search the mapped database. */
433extern struct datahead *__nscd_cache_search (request_type type,
434 const char *key,
435 size_t keylen,
436 const struct mapped_database *mapped,
437 size_t datalen)
438 attribute_hidden;
439
440/* Wrappers around read, readv and write that only read/write less than LEN
441 bytes on error or EOF. */
442extern ssize_t __readall (int fd, void *buf, size_t len)
443 attribute_hidden;
444extern ssize_t __readvall (int fd, const struct iovec *iov, int iovcnt)
445 attribute_hidden;
446extern ssize_t writeall (int fd, const void *buf, size_t len)
447 attribute_hidden;
448
449/* Get netlink timestamp counter from mapped area or zero. */
450extern uint32_t __nscd_get_nl_timestamp (void)
451 attribute_hidden;
452
453#endif /* nscd.h */
454

source code of glibc/nscd/nscd-client.h