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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_storage *ss, size_t salen)
20{
21 struct sockaddr *sa = (struct sockaddr *)ss;
22 ssize_t ret;
23 char *ip_addr = NULL;
24 int ip_len;
25
26 ip_len = dns_query(net, NULL, name, namelen, NULL, &ip_addr, NULL,
27 false);
28 if (ip_len > 0)
29 ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
30 else
31 ret = -ESRCH;
32 kfree(ip_addr);
33 return ret;
34}
35
36#else
37
38#include <linux/module.h>
39#include <linux/hash.h>
40#include <linux/string.h>
41#include <linux/kmod.h>
42#include <linux/slab.h>
43#include <linux/socket.h>
44#include <linux/seq_file.h>
45#include <linux/inet.h>
46#include <linux/sunrpc/clnt.h>
47#include <linux/sunrpc/addr.h>
48#include <linux/sunrpc/cache.h>
49#include <linux/sunrpc/svcauth.h>
50#include <linux/sunrpc/rpc_pipe_fs.h>
51#include <linux/nfs_fs.h>
52
53#include "nfs4_fs.h"
54#include "dns_resolve.h"
55#include "cache_lib.h"
56#include "netns.h"
57
58#define NFS_DNS_HASHBITS 4
59#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
60
61struct nfs_dns_ent {
62 struct cache_head h;
63
64 char *hostname;
65 size_t namelen;
66
67 struct sockaddr_storage addr;
68 size_t addrlen;
69 struct rcu_head rcu_head;
70};
71
72
73static void nfs_dns_ent_update(struct cache_head *cnew,
74 struct cache_head *ckey)
75{
76 struct nfs_dns_ent *new;
77 struct nfs_dns_ent *key;
78
79 new = container_of(cnew, struct nfs_dns_ent, h);
80 key = container_of(ckey, struct nfs_dns_ent, h);
81
82 memcpy(&new->addr, &key->addr, key->addrlen);
83 new->addrlen = key->addrlen;
84}
85
86static void nfs_dns_ent_init(struct cache_head *cnew,
87 struct cache_head *ckey)
88{
89 struct nfs_dns_ent *new;
90 struct nfs_dns_ent *key;
91
92 new = container_of(cnew, struct nfs_dns_ent, h);
93 key = container_of(ckey, struct nfs_dns_ent, h);
94
95 kfree(new->hostname);
96 new->hostname = kmemdup_nul(key->hostname, key->namelen, GFP_KERNEL);
97 if (new->hostname) {
98 new->namelen = key->namelen;
99 nfs_dns_ent_update(cnew, ckey);
100 } else {
101 new->namelen = 0;
102 new->addrlen = 0;
103 }
104}
105
106static void nfs_dns_ent_free_rcu(struct rcu_head *head)
107{
108 struct nfs_dns_ent *item;
109
110 item = container_of(head, struct nfs_dns_ent, rcu_head);
111 kfree(item->hostname);
112 kfree(item);
113}
114
115static void nfs_dns_ent_put(struct kref *ref)
116{
117 struct nfs_dns_ent *item;
118
119 item = container_of(ref, struct nfs_dns_ent, h.ref);
120 call_rcu(&item->rcu_head, nfs_dns_ent_free_rcu);
121}
122
123static struct cache_head *nfs_dns_ent_alloc(void)
124{
125 struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
126
127 if (item != NULL) {
128 item->hostname = NULL;
129 item->namelen = 0;
130 item->addrlen = 0;
131 return &item->h;
132 }
133 return NULL;
134};
135
136static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
137{
138 return hash_str(key->hostname, NFS_DNS_HASHBITS);
139}
140
141static void nfs_dns_request(struct cache_detail *cd,
142 struct cache_head *ch,
143 char **bpp, int *blen)
144{
145 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
146
147 qword_add(bpp, blen, key->hostname);
148 (*bpp)[-1] = '\n';
149}
150
151static int nfs_dns_upcall(struct cache_detail *cd,
152 struct cache_head *ch)
153{
154 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
155
156 if (test_and_set_bit(CACHE_PENDING, &ch->flags))
157 return 0;
158 if (!nfs_cache_upcall(cd, key->hostname))
159 return 0;
160 clear_bit(CACHE_PENDING, &ch->flags);
161 return sunrpc_cache_pipe_upcall_timeout(cd, ch);
162}
163
164static int nfs_dns_match(struct cache_head *ca,
165 struct cache_head *cb)
166{
167 struct nfs_dns_ent *a;
168 struct nfs_dns_ent *b;
169
170 a = container_of(ca, struct nfs_dns_ent, h);
171 b = container_of(cb, struct nfs_dns_ent, h);
172
173 if (a->namelen == 0 || a->namelen != b->namelen)
174 return 0;
175 return memcmp(a->hostname, b->hostname, a->namelen) == 0;
176}
177
178static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
179 struct cache_head *h)
180{
181 struct nfs_dns_ent *item;
182 long ttl;
183
184 if (h == NULL) {
185 seq_puts(m, "# ip address hostname ttl\n");
186 return 0;
187 }
188 item = container_of(h, struct nfs_dns_ent, h);
189 ttl = item->h.expiry_time - seconds_since_boot();
190 if (ttl < 0)
191 ttl = 0;
192
193 if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
194 char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
195
196 rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
197 seq_printf(m, "%15s ", buf);
198 } else
199 seq_puts(m, "<none> ");
200 seq_printf(m, "%15s %ld\n", item->hostname, ttl);
201 return 0;
202}
203
204static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
205 struct nfs_dns_ent *key)
206{
207 struct cache_head *ch;
208
209 ch = sunrpc_cache_lookup_rcu(cd,
210 &key->h,
211 nfs_dns_hash(key));
212 if (!ch)
213 return NULL;
214 return container_of(ch, struct nfs_dns_ent, h);
215}
216
217static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
218 struct nfs_dns_ent *new,
219 struct nfs_dns_ent *key)
220{
221 struct cache_head *ch;
222
223 ch = sunrpc_cache_update(cd,
224 &new->h, &key->h,
225 nfs_dns_hash(key));
226 if (!ch)
227 return NULL;
228 return container_of(ch, struct nfs_dns_ent, h);
229}
230
231static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
232{
233 char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
234 struct nfs_dns_ent key, *item;
235 unsigned int ttl;
236 ssize_t len;
237 int ret = -EINVAL;
238
239 if (buf[buflen-1] != '\n')
240 goto out;
241 buf[buflen-1] = '\0';
242
243 len = qword_get(&buf, buf1, sizeof(buf1));
244 if (len <= 0)
245 goto out;
246 key.addrlen = rpc_pton(cd->net, buf1, len,
247 (struct sockaddr *)&key.addr,
248 sizeof(key.addr));
249
250 len = qword_get(&buf, buf1, sizeof(buf1));
251 if (len <= 0)
252 goto out;
253
254 key.hostname = buf1;
255 key.namelen = len;
256 memset(&key.h, 0, sizeof(key.h));
257
258 if (get_uint(&buf, &ttl) < 0)
259 goto out;
260 if (ttl == 0)
261 goto out;
262 key.h.expiry_time = ttl + seconds_since_boot();
263
264 ret = -ENOMEM;
265 item = nfs_dns_lookup(cd, &key);
266 if (item == NULL)
267 goto out;
268
269 if (key.addrlen == 0)
270 set_bit(CACHE_NEGATIVE, &key.h.flags);
271
272 item = nfs_dns_update(cd, &key, item);
273 if (item == NULL)
274 goto out;
275
276 ret = 0;
277 cache_put(&item->h, cd);
278out:
279 return ret;
280}
281
282static int do_cache_lookup(struct cache_detail *cd,
283 struct nfs_dns_ent *key,
284 struct nfs_dns_ent **item,
285 struct nfs_cache_defer_req *dreq)
286{
287 int ret = -ENOMEM;
288
289 *item = nfs_dns_lookup(cd, key);
290 if (*item) {
291 ret = cache_check(cd, &(*item)->h, &dreq->req);
292 if (ret)
293 *item = NULL;
294 }
295 return ret;
296}
297
298static int do_cache_lookup_nowait(struct cache_detail *cd,
299 struct nfs_dns_ent *key,
300 struct nfs_dns_ent **item)
301{
302 int ret = -ENOMEM;
303
304 *item = nfs_dns_lookup(cd, key);
305 if (!*item)
306 goto out_err;
307 ret = -ETIMEDOUT;
308 if (!test_bit(CACHE_VALID, &(*item)->h.flags)
309 || (*item)->h.expiry_time < seconds_since_boot()
310 || cd->flush_time > (*item)->h.last_refresh)
311 goto out_put;
312 ret = -ENOENT;
313 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
314 goto out_put;
315 return 0;
316out_put:
317 cache_put(&(*item)->h, cd);
318out_err:
319 *item = NULL;
320 return ret;
321}
322
323static int do_cache_lookup_wait(struct cache_detail *cd,
324 struct nfs_dns_ent *key,
325 struct nfs_dns_ent **item)
326{
327 struct nfs_cache_defer_req *dreq;
328 int ret = -ENOMEM;
329
330 dreq = nfs_cache_defer_req_alloc();
331 if (!dreq)
332 goto out;
333 ret = do_cache_lookup(cd, key, item, dreq);
334 if (ret == -EAGAIN) {
335 ret = nfs_cache_wait_for_upcall(dreq);
336 if (!ret)
337 ret = do_cache_lookup_nowait(cd, key, item);
338 }
339 nfs_cache_defer_req_put(dreq);
340out:
341 return ret;
342}
343
344ssize_t nfs_dns_resolve_name(struct net *net, char *name,
345 size_t namelen, struct sockaddr_storage *ss, size_t salen)
346{
347 struct nfs_dns_ent key = {
348 .hostname = name,
349 .namelen = namelen,
350 };
351 struct nfs_dns_ent *item = NULL;
352 ssize_t ret;
353 struct nfs_net *nn = net_generic(net, nfs_net_id);
354
355 ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
356 if (ret == 0) {
357 if (salen >= item->addrlen) {
358 memcpy(ss, &item->addr, item->addrlen);
359 ret = item->addrlen;
360 } else
361 ret = -EOVERFLOW;
362 cache_put(&item->h, nn->nfs_dns_resolve);
363 } else if (ret == -ENOENT)
364 ret = -ESRCH;
365 return ret;
366}
367
368static struct cache_detail nfs_dns_resolve_template = {
369 .owner = THIS_MODULE,
370 .hash_size = NFS_DNS_HASHTBL_SIZE,
371 .name = "dns_resolve",
372 .cache_put = nfs_dns_ent_put,
373 .cache_upcall = nfs_dns_upcall,
374 .cache_request = nfs_dns_request,
375 .cache_parse = nfs_dns_parse,
376 .cache_show = nfs_dns_show,
377 .match = nfs_dns_match,
378 .init = nfs_dns_ent_init,
379 .update = nfs_dns_ent_update,
380 .alloc = nfs_dns_ent_alloc,
381};
382
383
384int nfs_dns_resolver_cache_init(struct net *net)
385{
386 int err;
387 struct nfs_net *nn = net_generic(net, nfs_net_id);
388
389 nn->nfs_dns_resolve = cache_create_net(&nfs_dns_resolve_template, net);
390 if (IS_ERR(nn->nfs_dns_resolve))
391 return PTR_ERR(nn->nfs_dns_resolve);
392
393 err = nfs_cache_register_net(net, nn->nfs_dns_resolve);
394 if (err)
395 goto err_reg;
396 return 0;
397
398err_reg:
399 cache_destroy_net(nn->nfs_dns_resolve, net);
400 return err;
401}
402
403void nfs_dns_resolver_cache_destroy(struct net *net)
404{
405 struct nfs_net *nn = net_generic(net, nfs_net_id);
406
407 nfs_cache_unregister_net(net, nn->nfs_dns_resolve);
408 cache_destroy_net(nn->nfs_dns_resolve, net);
409}
410
411static int nfs4_dns_net_init(struct net *net)
412{
413 return nfs_dns_resolver_cache_init(net);
414}
415
416static void nfs4_dns_net_exit(struct net *net)
417{
418 nfs_dns_resolver_cache_destroy(net);
419}
420
421static struct pernet_operations nfs4_dns_resolver_ops = {
422 .init = nfs4_dns_net_init,
423 .exit = nfs4_dns_net_exit,
424};
425
426static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
427 void *ptr)
428{
429 struct super_block *sb = ptr;
430 struct net *net = sb->s_fs_info;
431 struct nfs_net *nn = net_generic(net, nfs_net_id);
432 struct cache_detail *cd = nn->nfs_dns_resolve;
433 int ret = 0;
434
435 if (cd == NULL)
436 return 0;
437
438 if (!try_module_get(THIS_MODULE))
439 return 0;
440
441 switch (event) {
442 case RPC_PIPEFS_MOUNT:
443 ret = nfs_cache_register_sb(sb, cd);
444 break;
445 case RPC_PIPEFS_UMOUNT:
446 nfs_cache_unregister_sb(sb, cd);
447 break;
448 default:
449 ret = -ENOTSUPP;
450 break;
451 }
452 module_put(THIS_MODULE);
453 return ret;
454}
455
456static struct notifier_block nfs_dns_resolver_block = {
457 .notifier_call = rpc_pipefs_event,
458};
459
460int nfs_dns_resolver_init(void)
461{
462 int err;
463
464 err = register_pernet_subsys(&nfs4_dns_resolver_ops);
465 if (err < 0)
466 goto out;
467 err = rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
468 if (err < 0)
469 goto out1;
470 return 0;
471out1:
472 unregister_pernet_subsys(&nfs4_dns_resolver_ops);
473out:
474 return err;
475}
476
477void nfs_dns_resolver_destroy(void)
478{
479 rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
480 unregister_pernet_subsys(&nfs4_dns_resolver_ops);
481}
482#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