2 * linux/fs/nfs/dns_resolve.c
4 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
6 * Resolves DNS hostnames into valid ip addresses
9 #ifdef CONFIG_NFS_USE_KERNEL_DNS
11 #include <linux/sunrpc/clnt.h>
12 #include <linux/dns_resolver.h>
13 #include "dns_resolve.h"
15 ssize_t
nfs_dns_resolve_name(struct net
*net
, char *name
, size_t namelen
,
16 struct sockaddr
*sa
, size_t salen
)
22 ip_len
= dns_query(NULL
, name
, namelen
, NULL
, &ip_addr
, NULL
);
24 ret
= rpc_pton(net
, ip_addr
, ip_len
, sa
, salen
);
33 #include <linux/hash.h>
34 #include <linux/string.h>
35 #include <linux/kmod.h>
36 #include <linux/slab.h>
37 #include <linux/module.h>
38 #include <linux/socket.h>
39 #include <linux/seq_file.h>
40 #include <linux/inet.h>
41 #include <linux/sunrpc/clnt.h>
42 #include <linux/sunrpc/cache.h>
43 #include <linux/sunrpc/svcauth.h>
44 #include <linux/sunrpc/rpc_pipe_fs.h>
46 #include "dns_resolve.h"
47 #include "cache_lib.h"
50 #define NFS_DNS_HASHBITS 4
51 #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
59 struct sockaddr_storage addr
;
64 static void nfs_dns_ent_update(struct cache_head
*cnew
,
65 struct cache_head
*ckey
)
67 struct nfs_dns_ent
*new;
68 struct nfs_dns_ent
*key
;
70 new = container_of(cnew
, struct nfs_dns_ent
, h
);
71 key
= container_of(ckey
, struct nfs_dns_ent
, h
);
73 memcpy(&new->addr
, &key
->addr
, key
->addrlen
);
74 new->addrlen
= key
->addrlen
;
77 static void nfs_dns_ent_init(struct cache_head
*cnew
,
78 struct cache_head
*ckey
)
80 struct nfs_dns_ent
*new;
81 struct nfs_dns_ent
*key
;
83 new = container_of(cnew
, struct nfs_dns_ent
, h
);
84 key
= container_of(ckey
, struct nfs_dns_ent
, h
);
87 new->hostname
= kstrndup(key
->hostname
, key
->namelen
, GFP_KERNEL
);
89 new->namelen
= key
->namelen
;
90 nfs_dns_ent_update(cnew
, ckey
);
97 static void nfs_dns_ent_put(struct kref
*ref
)
99 struct nfs_dns_ent
*item
;
101 item
= container_of(ref
, struct nfs_dns_ent
, h
.ref
);
102 kfree(item
->hostname
);
106 static struct cache_head
*nfs_dns_ent_alloc(void)
108 struct nfs_dns_ent
*item
= kmalloc(sizeof(*item
), GFP_KERNEL
);
111 item
->hostname
= NULL
;
119 static unsigned int nfs_dns_hash(const struct nfs_dns_ent
*key
)
121 return hash_str(key
->hostname
, NFS_DNS_HASHBITS
);
124 static void nfs_dns_request(struct cache_detail
*cd
,
125 struct cache_head
*ch
,
126 char **bpp
, int *blen
)
128 struct nfs_dns_ent
*key
= container_of(ch
, struct nfs_dns_ent
, h
);
130 qword_add(bpp
, blen
, key
->hostname
);
134 static int nfs_dns_upcall(struct cache_detail
*cd
,
135 struct cache_head
*ch
)
137 struct nfs_dns_ent
*key
= container_of(ch
, struct nfs_dns_ent
, h
);
140 ret
= nfs_cache_upcall(cd
, key
->hostname
);
142 ret
= sunrpc_cache_pipe_upcall(cd
, ch
, nfs_dns_request
);
146 static int nfs_dns_match(struct cache_head
*ca
,
147 struct cache_head
*cb
)
149 struct nfs_dns_ent
*a
;
150 struct nfs_dns_ent
*b
;
152 a
= container_of(ca
, struct nfs_dns_ent
, h
);
153 b
= container_of(cb
, struct nfs_dns_ent
, h
);
155 if (a
->namelen
== 0 || a
->namelen
!= b
->namelen
)
157 return memcmp(a
->hostname
, b
->hostname
, a
->namelen
) == 0;
160 static int nfs_dns_show(struct seq_file
*m
, struct cache_detail
*cd
,
161 struct cache_head
*h
)
163 struct nfs_dns_ent
*item
;
167 seq_puts(m
, "# ip address hostname ttl\n");
170 item
= container_of(h
, struct nfs_dns_ent
, h
);
171 ttl
= item
->h
.expiry_time
- seconds_since_boot();
175 if (!test_bit(CACHE_NEGATIVE
, &h
->flags
)) {
176 char buf
[INET6_ADDRSTRLEN
+IPV6_SCOPE_ID_LEN
+1];
178 rpc_ntop((struct sockaddr
*)&item
->addr
, buf
, sizeof(buf
));
179 seq_printf(m
, "%15s ", buf
);
181 seq_puts(m
, "<none> ");
182 seq_printf(m
, "%15s %ld\n", item
->hostname
, ttl
);
186 static struct nfs_dns_ent
*nfs_dns_lookup(struct cache_detail
*cd
,
187 struct nfs_dns_ent
*key
)
189 struct cache_head
*ch
;
191 ch
= sunrpc_cache_lookup(cd
,
196 return container_of(ch
, struct nfs_dns_ent
, h
);
199 static struct nfs_dns_ent
*nfs_dns_update(struct cache_detail
*cd
,
200 struct nfs_dns_ent
*new,
201 struct nfs_dns_ent
*key
)
203 struct cache_head
*ch
;
205 ch
= sunrpc_cache_update(cd
,
210 return container_of(ch
, struct nfs_dns_ent
, h
);
213 static int nfs_dns_parse(struct cache_detail
*cd
, char *buf
, int buflen
)
215 char buf1
[NFS_DNS_HOSTNAME_MAXLEN
+1];
216 struct nfs_dns_ent key
, *item
;
221 if (buf
[buflen
-1] != '\n')
223 buf
[buflen
-1] = '\0';
225 len
= qword_get(&buf
, buf1
, sizeof(buf1
));
228 key
.addrlen
= rpc_pton(cd
->net
, buf1
, len
,
229 (struct sockaddr
*)&key
.addr
,
232 len
= qword_get(&buf
, buf1
, sizeof(buf1
));
238 memset(&key
.h
, 0, sizeof(key
.h
));
240 ttl
= get_expiry(&buf
);
243 key
.h
.expiry_time
= ttl
+ seconds_since_boot();
246 item
= nfs_dns_lookup(cd
, &key
);
250 if (key
.addrlen
== 0)
251 set_bit(CACHE_NEGATIVE
, &key
.h
.flags
);
253 item
= nfs_dns_update(cd
, &key
, item
);
258 cache_put(&item
->h
, cd
);
263 static int do_cache_lookup(struct cache_detail
*cd
,
264 struct nfs_dns_ent
*key
,
265 struct nfs_dns_ent
**item
,
266 struct nfs_cache_defer_req
*dreq
)
270 *item
= nfs_dns_lookup(cd
, key
);
272 ret
= cache_check(cd
, &(*item
)->h
, &dreq
->req
);
279 static int do_cache_lookup_nowait(struct cache_detail
*cd
,
280 struct nfs_dns_ent
*key
,
281 struct nfs_dns_ent
**item
)
285 *item
= nfs_dns_lookup(cd
, key
);
289 if (!test_bit(CACHE_VALID
, &(*item
)->h
.flags
)
290 || (*item
)->h
.expiry_time
< seconds_since_boot()
291 || cd
->flush_time
> (*item
)->h
.last_refresh
)
294 if (test_bit(CACHE_NEGATIVE
, &(*item
)->h
.flags
))
298 cache_put(&(*item
)->h
, cd
);
304 static int do_cache_lookup_wait(struct cache_detail
*cd
,
305 struct nfs_dns_ent
*key
,
306 struct nfs_dns_ent
**item
)
308 struct nfs_cache_defer_req
*dreq
;
311 dreq
= nfs_cache_defer_req_alloc();
314 ret
= do_cache_lookup(cd
, key
, item
, dreq
);
315 if (ret
== -EAGAIN
) {
316 ret
= nfs_cache_wait_for_upcall(dreq
);
318 ret
= do_cache_lookup_nowait(cd
, key
, item
);
320 nfs_cache_defer_req_put(dreq
);
325 ssize_t
nfs_dns_resolve_name(struct net
*net
, char *name
,
326 size_t namelen
, struct sockaddr
*sa
, size_t salen
)
328 struct nfs_dns_ent key
= {
332 struct nfs_dns_ent
*item
= NULL
;
334 struct nfs_net
*nn
= net_generic(net
, nfs_net_id
);
336 ret
= do_cache_lookup_wait(nn
->nfs_dns_resolve
, &key
, &item
);
338 if (salen
>= item
->addrlen
) {
339 memcpy(sa
, &item
->addr
, item
->addrlen
);
343 cache_put(&item
->h
, nn
->nfs_dns_resolve
);
344 } else if (ret
== -ENOENT
)
349 int nfs_dns_resolver_cache_init(struct net
*net
)
352 struct nfs_net
*nn
= net_generic(net
, nfs_net_id
);
353 struct cache_detail
*cd
;
354 struct cache_head
**tbl
;
356 cd
= kzalloc(sizeof(struct cache_detail
), GFP_KERNEL
);
360 tbl
= kzalloc(NFS_DNS_HASHTBL_SIZE
* sizeof(struct cache_head
*),
365 cd
->owner
= THIS_MODULE
,
366 cd
->hash_size
= NFS_DNS_HASHTBL_SIZE
,
367 cd
->hash_table
= tbl
,
368 cd
->name
= "dns_resolve",
369 cd
->cache_put
= nfs_dns_ent_put
,
370 cd
->cache_upcall
= nfs_dns_upcall
,
371 cd
->cache_parse
= nfs_dns_parse
,
372 cd
->cache_show
= nfs_dns_show
,
373 cd
->match
= nfs_dns_match
,
374 cd
->init
= nfs_dns_ent_init
,
375 cd
->update
= nfs_dns_ent_update
,
376 cd
->alloc
= nfs_dns_ent_alloc
,
379 err
= nfs_cache_register_net(net
, cd
);
382 nn
->nfs_dns_resolve
= cd
;
386 nfs_cache_destroy(cd
);
387 kfree(cd
->hash_table
);
394 void nfs_dns_resolver_cache_destroy(struct net
*net
)
396 struct nfs_net
*nn
= net_generic(net
, nfs_net_id
);
397 struct cache_detail
*cd
= nn
->nfs_dns_resolve
;
399 nfs_cache_unregister_net(net
, cd
);
400 nfs_cache_destroy(cd
);
401 kfree(cd
->hash_table
);
405 static int rpc_pipefs_event(struct notifier_block
*nb
, unsigned long event
,
408 struct super_block
*sb
= ptr
;
409 struct net
*net
= sb
->s_fs_info
;
410 struct nfs_net
*nn
= net_generic(net
, nfs_net_id
);
411 struct cache_detail
*cd
= nn
->nfs_dns_resolve
;
417 if (!try_module_get(THIS_MODULE
))
421 case RPC_PIPEFS_MOUNT
:
422 ret
= nfs_cache_register_sb(sb
, cd
);
424 case RPC_PIPEFS_UMOUNT
:
425 nfs_cache_unregister_sb(sb
, cd
);
431 module_put(THIS_MODULE
);
435 static struct notifier_block nfs_dns_resolver_block
= {
436 .notifier_call
= rpc_pipefs_event
,
439 int nfs_dns_resolver_init(void)
441 return rpc_pipefs_notifier_register(&nfs_dns_resolver_block
);
444 void nfs_dns_resolver_destroy(void)
446 rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block
);