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>
14 ssize_t
nfs_dns_resolve_name(char *name
, size_t namelen
,
15 struct sockaddr
*sa
, size_t salen
)
21 ip_len
= dns_query(NULL
, name
, namelen
, NULL
, &ip_addr
, NULL
);
23 ret
= rpc_pton(ip_addr
, ip_len
, sa
, salen
);
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>
44 #include "dns_resolve.h"
45 #include "cache_lib.h"
47 #define NFS_DNS_HASHBITS 4
48 #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
50 static struct cache_head
*nfs_dns_table
[NFS_DNS_HASHTBL_SIZE
];
58 struct sockaddr_storage addr
;
63 static void nfs_dns_ent_update(struct cache_head
*cnew
,
64 struct cache_head
*ckey
)
66 struct nfs_dns_ent
*new;
67 struct nfs_dns_ent
*key
;
69 new = container_of(cnew
, struct nfs_dns_ent
, h
);
70 key
= container_of(ckey
, struct nfs_dns_ent
, h
);
72 memcpy(&new->addr
, &key
->addr
, key
->addrlen
);
73 new->addrlen
= key
->addrlen
;
76 static void nfs_dns_ent_init(struct cache_head
*cnew
,
77 struct cache_head
*ckey
)
79 struct nfs_dns_ent
*new;
80 struct nfs_dns_ent
*key
;
82 new = container_of(cnew
, struct nfs_dns_ent
, h
);
83 key
= container_of(ckey
, struct nfs_dns_ent
, h
);
86 new->hostname
= kstrndup(key
->hostname
, key
->namelen
, GFP_KERNEL
);
88 new->namelen
= key
->namelen
;
89 nfs_dns_ent_update(cnew
, ckey
);
96 static void nfs_dns_ent_put(struct kref
*ref
)
98 struct nfs_dns_ent
*item
;
100 item
= container_of(ref
, struct nfs_dns_ent
, h
.ref
);
101 kfree(item
->hostname
);
105 static struct cache_head
*nfs_dns_ent_alloc(void)
107 struct nfs_dns_ent
*item
= kmalloc(sizeof(*item
), GFP_KERNEL
);
110 item
->hostname
= NULL
;
118 static unsigned int nfs_dns_hash(const struct nfs_dns_ent
*key
)
120 return hash_str(key
->hostname
, NFS_DNS_HASHBITS
);
123 static void nfs_dns_request(struct cache_detail
*cd
,
124 struct cache_head
*ch
,
125 char **bpp
, int *blen
)
127 struct nfs_dns_ent
*key
= container_of(ch
, struct nfs_dns_ent
, h
);
129 qword_add(bpp
, blen
, key
->hostname
);
133 static int nfs_dns_upcall(struct cache_detail
*cd
,
134 struct cache_head
*ch
)
136 struct nfs_dns_ent
*key
= container_of(ch
, struct nfs_dns_ent
, h
);
139 ret
= nfs_cache_upcall(cd
, key
->hostname
);
141 ret
= sunrpc_cache_pipe_upcall(cd
, ch
, nfs_dns_request
);
145 static int nfs_dns_match(struct cache_head
*ca
,
146 struct cache_head
*cb
)
148 struct nfs_dns_ent
*a
;
149 struct nfs_dns_ent
*b
;
151 a
= container_of(ca
, struct nfs_dns_ent
, h
);
152 b
= container_of(cb
, struct nfs_dns_ent
, h
);
154 if (a
->namelen
== 0 || a
->namelen
!= b
->namelen
)
156 return memcmp(a
->hostname
, b
->hostname
, a
->namelen
) == 0;
159 static int nfs_dns_show(struct seq_file
*m
, struct cache_detail
*cd
,
160 struct cache_head
*h
)
162 struct nfs_dns_ent
*item
;
166 seq_puts(m
, "# ip address hostname ttl\n");
169 item
= container_of(h
, struct nfs_dns_ent
, h
);
170 ttl
= item
->h
.expiry_time
- seconds_since_boot();
174 if (!test_bit(CACHE_NEGATIVE
, &h
->flags
)) {
175 char buf
[INET6_ADDRSTRLEN
+IPV6_SCOPE_ID_LEN
+1];
177 rpc_ntop((struct sockaddr
*)&item
->addr
, buf
, sizeof(buf
));
178 seq_printf(m
, "%15s ", buf
);
180 seq_puts(m
, "<none> ");
181 seq_printf(m
, "%15s %ld\n", item
->hostname
, ttl
);
185 static struct nfs_dns_ent
*nfs_dns_lookup(struct cache_detail
*cd
,
186 struct nfs_dns_ent
*key
)
188 struct cache_head
*ch
;
190 ch
= sunrpc_cache_lookup(cd
,
195 return container_of(ch
, struct nfs_dns_ent
, h
);
198 static struct nfs_dns_ent
*nfs_dns_update(struct cache_detail
*cd
,
199 struct nfs_dns_ent
*new,
200 struct nfs_dns_ent
*key
)
202 struct cache_head
*ch
;
204 ch
= sunrpc_cache_update(cd
,
209 return container_of(ch
, struct nfs_dns_ent
, h
);
212 static int nfs_dns_parse(struct cache_detail
*cd
, char *buf
, int buflen
)
214 char buf1
[NFS_DNS_HOSTNAME_MAXLEN
+1];
215 struct nfs_dns_ent key
, *item
;
220 if (buf
[buflen
-1] != '\n')
222 buf
[buflen
-1] = '\0';
224 len
= qword_get(&buf
, buf1
, sizeof(buf1
));
227 key
.addrlen
= rpc_pton(buf1
, len
,
228 (struct sockaddr
*)&key
.addr
,
231 len
= qword_get(&buf
, buf1
, sizeof(buf1
));
237 memset(&key
.h
, 0, sizeof(key
.h
));
239 ttl
= get_expiry(&buf
);
242 key
.h
.expiry_time
= ttl
+ seconds_since_boot();
245 item
= nfs_dns_lookup(cd
, &key
);
249 if (key
.addrlen
== 0)
250 set_bit(CACHE_NEGATIVE
, &key
.h
.flags
);
252 item
= nfs_dns_update(cd
, &key
, item
);
257 cache_put(&item
->h
, cd
);
262 static 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
,
277 static 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
)
284 *item
= nfs_dns_lookup(cd
, key
);
286 ret
= cache_check(cd
, &(*item
)->h
, &dreq
->req
);
293 static int do_cache_lookup_nowait(struct cache_detail
*cd
,
294 struct nfs_dns_ent
*key
,
295 struct nfs_dns_ent
**item
)
299 *item
= nfs_dns_lookup(cd
, key
);
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
)
308 if (test_bit(CACHE_NEGATIVE
, &(*item
)->h
.flags
))
312 cache_put(&(*item
)->h
, cd
);
318 static int do_cache_lookup_wait(struct cache_detail
*cd
,
319 struct nfs_dns_ent
*key
,
320 struct nfs_dns_ent
**item
)
322 struct nfs_cache_defer_req
*dreq
;
325 dreq
= nfs_cache_defer_req_alloc();
328 ret
= do_cache_lookup(cd
, key
, item
, dreq
);
329 if (ret
== -EAGAIN
) {
330 ret
= nfs_cache_wait_for_upcall(dreq
);
332 ret
= do_cache_lookup_nowait(cd
, key
, item
);
334 nfs_cache_defer_req_put(dreq
);
339 ssize_t
nfs_dns_resolve_name(char *name
, size_t namelen
,
340 struct sockaddr
*sa
, size_t salen
)
342 struct nfs_dns_ent key
= {
346 struct nfs_dns_ent
*item
= NULL
;
349 ret
= do_cache_lookup_wait(&nfs_dns_resolve
, &key
, &item
);
351 if (salen
>= item
->addrlen
) {
352 memcpy(sa
, &item
->addr
, item
->addrlen
);
356 cache_put(&item
->h
, &nfs_dns_resolve
);
357 } else if (ret
== -ENOENT
)
362 int nfs_dns_resolver_init(void)
364 return nfs_cache_register(&nfs_dns_resolve
);
367 void nfs_dns_resolver_destroy(void)
369 nfs_cache_unregister(&nfs_dns_resolve
);