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);