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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/nfs/dns_resolve.c
4 *
5 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
6 *
7 * Resolves DNS hostnames into valid ip addresses
8 */
9
10#ifdef CONFIG_NFS_USE_KERNEL_DNS
11
12#include <linux/module.h>
13#include <linux/sunrpc/clnt.h>
14#include <linux/sunrpc/addr.h>
15#include <linux/dns_resolver.h>
16#include "dns_resolve.h"
17
18ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen,
19 struct sockaddr *sa, size_t salen)
20{
21 ssize_t ret;
22 char *ip_addr = NULL;
23 int ip_len;
24
25 ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
26 if (ip_len > 0)
27 ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
28 else
29 ret = -ESRCH;
30 kfree(ip_addr);
31 return ret;
32}
33
34#else
35
36#include <linux/module.h>
37#include <linux/hash.h>
38#include <linux/string.h>
39#include <linux/kmod.h>
40#include <linux/slab.h>
41#include <linux/module.h>
42#include <linux/socket.h>
43#include <linux/seq_file.h>
44#include <linux/inet.h>
45#include <linux/sunrpc/clnt.h>
46#include <linux/sunrpc/addr.h>
47#include <linux/sunrpc/cache.h>
48#include <linux/sunrpc/svcauth.h>
49#include <linux/sunrpc/rpc_pipe_fs.h>
50#include <linux/nfs_fs.h>
51
52#include "nfs4_fs.h"
53#include "dns_resolve.h"
54#include "cache_lib.h"
55#include "netns.h"
56
57#define NFS_DNS_HASHBITS 4
58#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
59
60struct nfs_dns_ent {
61 struct cache_head h;
62
63 char *hostname;
64 size_t namelen;
65
66 struct sockaddr_storage addr;
67 size_t addrlen;
68};
69
70
71static void nfs_dns_ent_update(struct cache_head *cnew,
72 struct cache_head *ckey)
73{
74 struct nfs_dns_ent *new;
75 struct nfs_dns_ent *key;
76
77 new = container_of(cnew, struct nfs_dns_ent, h);
78 key = container_of(ckey, struct nfs_dns_ent, h);
79
80 memcpy(&new->addr, &key->addr, key->addrlen);
81 new->addrlen = key->addrlen;
82}
83
84static void nfs_dns_ent_init(struct cache_head *cnew,
85 struct cache_head *ckey)
86{
87 struct nfs_dns_ent *new;
88 struct nfs_dns_ent *key;
89
90 new = container_of(cnew, struct nfs_dns_ent, h);
91 key = container_of(ckey, struct nfs_dns_ent, h);
92
93 kfree(new->hostname);
94 new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
95 if (new->hostname) {
96 new->namelen = key->namelen;
97 nfs_dns_ent_update(cnew, ckey);
98 } else {
99 new->namelen = 0;
100 new->addrlen = 0;
101 }
102}
103
104static void nfs_dns_ent_put(struct kref *ref)
105{
106 struct nfs_dns_ent *item;
107
108 item = container_of(ref, struct nfs_dns_ent, h.ref);
109 kfree(item->hostname);
110 kfree(item);
111}
112
113static struct cache_head *nfs_dns_ent_alloc(void)
114{
115 struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
116
117 if (item != NULL) {
118 item->hostname = NULL;
119 item->namelen = 0;
120 item->addrlen = 0;
121 return &item->h;
122 }
123 return NULL;
124};
125
126static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
127{
128 return hash_str(key->hostname, NFS_DNS_HASHBITS);
129}
130
131static void nfs_dns_request(struct cache_detail *cd,
132 struct cache_head *ch,
133 char **bpp, int *blen)
134{
135 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
136
137 qword_add(bpp, blen, key->hostname);
138 (*bpp)[-1] = '\n';
139}
140
141static int nfs_dns_upcall(struct cache_detail *cd,
142 struct cache_head *ch)
143{
144 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
145 int ret;
146
147 ret = nfs_cache_upcall(cd, key->hostname);
148 if (ret)
149 ret = sunrpc_cache_pipe_upcall(cd, ch);
150 return ret;
151}
152
153static int nfs_dns_match(struct cache_head *ca,
154 struct cache_head *cb)
155{
156 struct nfs_dns_ent *a;
157 struct nfs_dns_ent *b;
158
159 a = container_of(ca, struct nfs_dns_ent, h);
160 b = container_of(cb, struct nfs_dns_ent, h);
161
162 if (a->namelen == 0 || a->namelen != b->namelen)
163 return 0;
164 return memcmp(a->hostname, b->hostname, a->namelen) == 0;
165}
166
167static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
168 struct cache_head *h)
169{
170 struct nfs_dns_ent *item;
171 long ttl;
172
173 if (h == NULL) {
174 seq_puts(m, "# ip address hostname ttl\n");
175 return 0;
176 }
177 item = container_of(h, struct nfs_dns_ent, h);
178 ttl = item->h.expiry_time - seconds_since_boot();
179 if (ttl < 0)
180 ttl = 0;
181
182 if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
183 char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
184
185 rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
186 seq_printf(m, "%15s ", buf);
187 } else
188 seq_puts(m, "<none> ");
189 seq_printf(m, "%15s %ld\n", item->hostname, ttl);
190 return 0;
191}
192
193static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
194 struct nfs_dns_ent *key)
195{
196 struct cache_head *ch;
197
198 ch = sunrpc_cache_lookup(cd,
199 &key->h,
200 nfs_dns_hash(key));
201 if (!ch)
202 return NULL;
203 return container_of(ch, struct nfs_dns_ent, h);
204}
205
206static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
207 struct nfs_dns_ent *new,
208 struct nfs_dns_ent *key)
209{
210 struct cache_head *ch;
211
212 ch = sunrpc_cache_update(cd,
213 &new->h, &key->h,
214 nfs_dns_hash(key));
215 if (!ch)
216 return NULL;
217 return container_of(ch, struct nfs_dns_ent, h);
218}
219
220static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
221{
222 char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
223 struct nfs_dns_ent key, *item;
224 unsigned int ttl;
225 ssize_t len;
226 int ret = -EINVAL;
227
228 if (buf[buflen-1] != '\n')
229 goto out;
230 buf[buflen-1] = '\0';
231
232 len = qword_get(&buf, buf1, sizeof(buf1));
233 if (len <= 0)
234 goto out;
235 key.addrlen = rpc_pton(cd->net, buf1, len,
236 (struct sockaddr *)&key.addr,
237 sizeof(key.addr));
238
239 len = qword_get(&buf, buf1, sizeof(buf1));
240 if (len <= 0)
241 goto out;
242
243 key.hostname = buf1;
244 key.namelen = len;
245 memset(&key.h, 0, sizeof(key.h));
246
247 if (get_uint(&buf, &ttl) < 0)
248 goto out;
249 if (ttl == 0)
250 goto out;
251 key.h.expiry_time = ttl + seconds_since_boot();
252
253 ret = -ENOMEM;
254 item = nfs_dns_lookup(cd, &key);
255 if (item == NULL)
256 goto out;
257
258 if (key.addrlen == 0)
259 set_bit(CACHE_NEGATIVE, &key.h.flags);
260
261 item = nfs_dns_update(cd, &key, item);
262 if (item == NULL)
263 goto out;
264
265 ret = 0;
266 cache_put(&item->h, cd);
267out:
268 return ret;
269}
270
271static int do_cache_lookup(struct cache_detail *cd,
272 struct nfs_dns_ent *key,
273 struct nfs_dns_ent **item,
274 struct nfs_cache_defer_req *dreq)
275{
276 int ret = -ENOMEM;
277
278 *item = nfs_dns_lookup(cd, key);
279 if (*item) {
280 ret = cache_check(cd, &(*item)->h, &dreq->req);
281 if (ret)
282 *item = NULL;
283 }
284 return ret;
285}
286
287static int do_cache_lookup_nowait(struct cache_detail *cd,
288 struct nfs_dns_ent *key,
289 struct nfs_dns_ent **item)
290{
291 int ret = -ENOMEM;
292
293 *item = nfs_dns_lookup(cd, key);
294 if (!*item)
295 goto out_err;
296 ret = -ETIMEDOUT;
297 if (!test_bit(CACHE_VALID, &(*item)->h.flags)
298 || (*item)->h.expiry_time < seconds_since_boot()
299 || cd->flush_time > (*item)->h.last_refresh)
300 goto out_put;
301 ret = -ENOENT;
302 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
303 goto out_put;
304 return 0;
305out_put:
306 cache_put(&(*item)->h, cd);
307out_err:
308 *item = NULL;
309 return ret;
310}
311
312static int do_cache_lookup_wait(struct cache_detail *cd,
313 struct nfs_dns_ent *key,
314 struct nfs_dns_ent **item)
315{
316 struct nfs_cache_defer_req *dreq;
317 int ret = -ENOMEM;
318
319 dreq = nfs_cache_defer_req_alloc();
320 if (!dreq)
321 goto out;
322 ret = do_cache_lookup(cd, key, item, dreq);
323 if (ret == -EAGAIN) {
324 ret = nfs_cache_wait_for_upcall(dreq);
325 if (!ret)
326 ret = do_cache_lookup_nowait(cd, key, item);
327 }
328 nfs_cache_defer_req_put(dreq);
329out:
330 return ret;
331}
332
333ssize_t nfs_dns_resolve_name(struct net *net, char *name,
334 size_t namelen, struct sockaddr *sa, size_t salen)
335{
336 struct nfs_dns_ent key = {
337 .hostname = name,
338 .namelen = namelen,
339 };
340 struct nfs_dns_ent *item = NULL;
341 ssize_t ret;
342 struct nfs_net *nn = net_generic(net, nfs_net_id);
343
344 ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
345 if (ret == 0) {
346 if (salen >= item->addrlen) {
347 memcpy(sa, &item->addr, item->addrlen);
348 ret = item->addrlen;
349 } else
350 ret = -EOVERFLOW;
351 cache_put(&item->h, nn->nfs_dns_resolve);
352 } else if (ret == -ENOENT)
353 ret = -ESRCH;
354 return ret;
355}
356
357static struct cache_detail nfs_dns_resolve_template = {
358 .owner = THIS_MODULE,
359 .hash_size = NFS_DNS_HASHTBL_SIZE,
360 .name = "dns_resolve",
361 .cache_put = nfs_dns_ent_put,
362 .cache_upcall = nfs_dns_upcall,
363 .cache_request = nfs_dns_request,
364 .cache_parse = nfs_dns_parse,
365 .cache_show = nfs_dns_show,
366 .match = nfs_dns_match,
367 .init = nfs_dns_ent_init,
368 .update = nfs_dns_ent_update,
369 .alloc = nfs_dns_ent_alloc,
370};
371
372
373int nfs_dns_resolver_cache_init(struct net *net)
374{
375 int err;
376 struct nfs_net *nn = net_generic(net, nfs_net_id);
377
378 nn->nfs_dns_resolve = cache_create_net(&nfs_dns_resolve_template, net);
379 if (IS_ERR(nn->nfs_dns_resolve))
380 return PTR_ERR(nn->nfs_dns_resolve);
381
382 err = nfs_cache_register_net(net, nn->nfs_dns_resolve);
383 if (err)
384 goto err_reg;
385 return 0;
386
387err_reg:
388 cache_destroy_net(nn->nfs_dns_resolve, net);
389 return err;
390}
391
392void nfs_dns_resolver_cache_destroy(struct net *net)
393{
394 struct nfs_net *nn = net_generic(net, nfs_net_id);
395
396 nfs_cache_unregister_net(net, nn->nfs_dns_resolve);
397 cache_destroy_net(nn->nfs_dns_resolve, net);
398}
399
400static int nfs4_dns_net_init(struct net *net)
401{
402 return nfs_dns_resolver_cache_init(net);
403}
404
405static void nfs4_dns_net_exit(struct net *net)
406{
407 nfs_dns_resolver_cache_destroy(net);
408}
409
410static struct pernet_operations nfs4_dns_resolver_ops = {
411 .init = nfs4_dns_net_init,
412 .exit = nfs4_dns_net_exit,
413};
414
415static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
416 void *ptr)
417{
418 struct super_block *sb = ptr;
419 struct net *net = sb->s_fs_info;
420 struct nfs_net *nn = net_generic(net, nfs_net_id);
421 struct cache_detail *cd = nn->nfs_dns_resolve;
422 int ret = 0;
423
424 if (cd == NULL)
425 return 0;
426
427 if (!try_module_get(THIS_MODULE))
428 return 0;
429
430 switch (event) {
431 case RPC_PIPEFS_MOUNT:
432 ret = nfs_cache_register_sb(sb, cd);
433 break;
434 case RPC_PIPEFS_UMOUNT:
435 nfs_cache_unregister_sb(sb, cd);
436 break;
437 default:
438 ret = -ENOTSUPP;
439 break;
440 }
441 module_put(THIS_MODULE);
442 return ret;
443}
444
445static struct notifier_block nfs_dns_resolver_block = {
446 .notifier_call = rpc_pipefs_event,
447};
448
449int nfs_dns_resolver_init(void)
450{
451 int err;
452
453 err = register_pernet_subsys(&nfs4_dns_resolver_ops);
454 if (err < 0)
455 goto out;
456 err = rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
457 if (err < 0)
458 goto out1;
459 return 0;
460out1:
461 unregister_pernet_subsys(&nfs4_dns_resolver_ops);
462out:
463 return err;
464}
465
466void nfs_dns_resolver_destroy(void)
467{
468 rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
469 unregister_pernet_subsys(&nfs4_dns_resolver_ops);
470}
471#endif
1/*
2 * linux/fs/nfs/dns_resolve.c
3 *
4 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
5 *
6 * Resolves DNS hostnames into valid ip addresses
7 */
8
9#ifdef CONFIG_NFS_USE_KERNEL_DNS
10
11#include <linux/sunrpc/clnt.h>
12#include <linux/dns_resolver.h>
13
14ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
15 struct sockaddr *sa, size_t salen)
16{
17 ssize_t ret;
18 char *ip_addr = NULL;
19 int ip_len;
20
21 ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
22 if (ip_len > 0)
23 ret = rpc_pton(ip_addr, ip_len, sa, salen);
24 else
25 ret = -ESRCH;
26 kfree(ip_addr);
27 return ret;
28}
29
30#else
31
32#include <linux/hash.h>
33#include <linux/string.h>
34#include <linux/kmod.h>
35#include <linux/slab.h>
36#include <linux/module.h>
37#include <linux/socket.h>
38#include <linux/seq_file.h>
39#include <linux/inet.h>
40#include <linux/sunrpc/clnt.h>
41#include <linux/sunrpc/cache.h>
42#include <linux/sunrpc/svcauth.h>
43
44#include "dns_resolve.h"
45#include "cache_lib.h"
46
47#define NFS_DNS_HASHBITS 4
48#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
49
50static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];
51
52struct nfs_dns_ent {
53 struct cache_head h;
54
55 char *hostname;
56 size_t namelen;
57
58 struct sockaddr_storage addr;
59 size_t addrlen;
60};
61
62
63static void nfs_dns_ent_update(struct cache_head *cnew,
64 struct cache_head *ckey)
65{
66 struct nfs_dns_ent *new;
67 struct nfs_dns_ent *key;
68
69 new = container_of(cnew, struct nfs_dns_ent, h);
70 key = container_of(ckey, struct nfs_dns_ent, h);
71
72 memcpy(&new->addr, &key->addr, key->addrlen);
73 new->addrlen = key->addrlen;
74}
75
76static void nfs_dns_ent_init(struct cache_head *cnew,
77 struct cache_head *ckey)
78{
79 struct nfs_dns_ent *new;
80 struct nfs_dns_ent *key;
81
82 new = container_of(cnew, struct nfs_dns_ent, h);
83 key = container_of(ckey, struct nfs_dns_ent, h);
84
85 kfree(new->hostname);
86 new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
87 if (new->hostname) {
88 new->namelen = key->namelen;
89 nfs_dns_ent_update(cnew, ckey);
90 } else {
91 new->namelen = 0;
92 new->addrlen = 0;
93 }
94}
95
96static void nfs_dns_ent_put(struct kref *ref)
97{
98 struct nfs_dns_ent *item;
99
100 item = container_of(ref, struct nfs_dns_ent, h.ref);
101 kfree(item->hostname);
102 kfree(item);
103}
104
105static struct cache_head *nfs_dns_ent_alloc(void)
106{
107 struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
108
109 if (item != NULL) {
110 item->hostname = NULL;
111 item->namelen = 0;
112 item->addrlen = 0;
113 return &item->h;
114 }
115 return NULL;
116};
117
118static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
119{
120 return hash_str(key->hostname, NFS_DNS_HASHBITS);
121}
122
123static void nfs_dns_request(struct cache_detail *cd,
124 struct cache_head *ch,
125 char **bpp, int *blen)
126{
127 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
128
129 qword_add(bpp, blen, key->hostname);
130 (*bpp)[-1] = '\n';
131}
132
133static int nfs_dns_upcall(struct cache_detail *cd,
134 struct cache_head *ch)
135{
136 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
137 int ret;
138
139 ret = nfs_cache_upcall(cd, key->hostname);
140 if (ret)
141 ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
142 return ret;
143}
144
145static int nfs_dns_match(struct cache_head *ca,
146 struct cache_head *cb)
147{
148 struct nfs_dns_ent *a;
149 struct nfs_dns_ent *b;
150
151 a = container_of(ca, struct nfs_dns_ent, h);
152 b = container_of(cb, struct nfs_dns_ent, h);
153
154 if (a->namelen == 0 || a->namelen != b->namelen)
155 return 0;
156 return memcmp(a->hostname, b->hostname, a->namelen) == 0;
157}
158
159static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
160 struct cache_head *h)
161{
162 struct nfs_dns_ent *item;
163 long ttl;
164
165 if (h == NULL) {
166 seq_puts(m, "# ip address hostname ttl\n");
167 return 0;
168 }
169 item = container_of(h, struct nfs_dns_ent, h);
170 ttl = item->h.expiry_time - seconds_since_boot();
171 if (ttl < 0)
172 ttl = 0;
173
174 if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
175 char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
176
177 rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
178 seq_printf(m, "%15s ", buf);
179 } else
180 seq_puts(m, "<none> ");
181 seq_printf(m, "%15s %ld\n", item->hostname, ttl);
182 return 0;
183}
184
185static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
186 struct nfs_dns_ent *key)
187{
188 struct cache_head *ch;
189
190 ch = sunrpc_cache_lookup(cd,
191 &key->h,
192 nfs_dns_hash(key));
193 if (!ch)
194 return NULL;
195 return container_of(ch, struct nfs_dns_ent, h);
196}
197
198static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
199 struct nfs_dns_ent *new,
200 struct nfs_dns_ent *key)
201{
202 struct cache_head *ch;
203
204 ch = sunrpc_cache_update(cd,
205 &new->h, &key->h,
206 nfs_dns_hash(key));
207 if (!ch)
208 return NULL;
209 return container_of(ch, struct nfs_dns_ent, h);
210}
211
212static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
213{
214 char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
215 struct nfs_dns_ent key, *item;
216 unsigned long ttl;
217 ssize_t len;
218 int ret = -EINVAL;
219
220 if (buf[buflen-1] != '\n')
221 goto out;
222 buf[buflen-1] = '\0';
223
224 len = qword_get(&buf, buf1, sizeof(buf1));
225 if (len <= 0)
226 goto out;
227 key.addrlen = rpc_pton(buf1, len,
228 (struct sockaddr *)&key.addr,
229 sizeof(key.addr));
230
231 len = qword_get(&buf, buf1, sizeof(buf1));
232 if (len <= 0)
233 goto out;
234
235 key.hostname = buf1;
236 key.namelen = len;
237 memset(&key.h, 0, sizeof(key.h));
238
239 ttl = get_expiry(&buf);
240 if (ttl == 0)
241 goto out;
242 key.h.expiry_time = ttl + seconds_since_boot();
243
244 ret = -ENOMEM;
245 item = nfs_dns_lookup(cd, &key);
246 if (item == NULL)
247 goto out;
248
249 if (key.addrlen == 0)
250 set_bit(CACHE_NEGATIVE, &key.h.flags);
251
252 item = nfs_dns_update(cd, &key, item);
253 if (item == NULL)
254 goto out;
255
256 ret = 0;
257 cache_put(&item->h, cd);
258out:
259 return ret;
260}
261
262static struct cache_detail nfs_dns_resolve = {
263 .owner = THIS_MODULE,
264 .hash_size = NFS_DNS_HASHTBL_SIZE,
265 .hash_table = nfs_dns_table,
266 .name = "dns_resolve",
267 .cache_put = nfs_dns_ent_put,
268 .cache_upcall = nfs_dns_upcall,
269 .cache_parse = nfs_dns_parse,
270 .cache_show = nfs_dns_show,
271 .match = nfs_dns_match,
272 .init = nfs_dns_ent_init,
273 .update = nfs_dns_ent_update,
274 .alloc = nfs_dns_ent_alloc,
275};
276
277static int do_cache_lookup(struct cache_detail *cd,
278 struct nfs_dns_ent *key,
279 struct nfs_dns_ent **item,
280 struct nfs_cache_defer_req *dreq)
281{
282 int ret = -ENOMEM;
283
284 *item = nfs_dns_lookup(cd, key);
285 if (*item) {
286 ret = cache_check(cd, &(*item)->h, &dreq->req);
287 if (ret)
288 *item = NULL;
289 }
290 return ret;
291}
292
293static int do_cache_lookup_nowait(struct cache_detail *cd,
294 struct nfs_dns_ent *key,
295 struct nfs_dns_ent **item)
296{
297 int ret = -ENOMEM;
298
299 *item = nfs_dns_lookup(cd, key);
300 if (!*item)
301 goto out_err;
302 ret = -ETIMEDOUT;
303 if (!test_bit(CACHE_VALID, &(*item)->h.flags)
304 || (*item)->h.expiry_time < seconds_since_boot()
305 || cd->flush_time > (*item)->h.last_refresh)
306 goto out_put;
307 ret = -ENOENT;
308 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
309 goto out_put;
310 return 0;
311out_put:
312 cache_put(&(*item)->h, cd);
313out_err:
314 *item = NULL;
315 return ret;
316}
317
318static int do_cache_lookup_wait(struct cache_detail *cd,
319 struct nfs_dns_ent *key,
320 struct nfs_dns_ent **item)
321{
322 struct nfs_cache_defer_req *dreq;
323 int ret = -ENOMEM;
324
325 dreq = nfs_cache_defer_req_alloc();
326 if (!dreq)
327 goto out;
328 ret = do_cache_lookup(cd, key, item, dreq);
329 if (ret == -EAGAIN) {
330 ret = nfs_cache_wait_for_upcall(dreq);
331 if (!ret)
332 ret = do_cache_lookup_nowait(cd, key, item);
333 }
334 nfs_cache_defer_req_put(dreq);
335out:
336 return ret;
337}
338
339ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
340 struct sockaddr *sa, size_t salen)
341{
342 struct nfs_dns_ent key = {
343 .hostname = name,
344 .namelen = namelen,
345 };
346 struct nfs_dns_ent *item = NULL;
347 ssize_t ret;
348
349 ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
350 if (ret == 0) {
351 if (salen >= item->addrlen) {
352 memcpy(sa, &item->addr, item->addrlen);
353 ret = item->addrlen;
354 } else
355 ret = -EOVERFLOW;
356 cache_put(&item->h, &nfs_dns_resolve);
357 } else if (ret == -ENOENT)
358 ret = -ESRCH;
359 return ret;
360}
361
362int nfs_dns_resolver_init(void)
363{
364 return nfs_cache_register(&nfs_dns_resolve);
365}
366
367void nfs_dns_resolver_destroy(void)
368{
369 nfs_cache_unregister(&nfs_dns_resolve);
370}
371
372#endif