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/module.h>
12 #include <linux/sunrpc/clnt.h>
13 #include <linux/sunrpc/addr.h>
14 #include <linux/dns_resolver.h>
15 #include "dns_resolve.h"
17 ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen,
18 struct sockaddr *sa, size_t salen)
24 ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
26 ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
32 EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
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>
51 #include "dns_resolve.h"
52 #include "cache_lib.h"
55 #define NFS_DNS_HASHBITS 4
56 #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
64 struct sockaddr_storage addr;
69 static void nfs_dns_ent_update(struct cache_head *cnew,
70 struct cache_head *ckey)
72 struct nfs_dns_ent *new;
73 struct nfs_dns_ent *key;
75 new = container_of(cnew, struct nfs_dns_ent, h);
76 key = container_of(ckey, struct nfs_dns_ent, h);
78 memcpy(&new->addr, &key->addr, key->addrlen);
79 new->addrlen = key->addrlen;
82 static void nfs_dns_ent_init(struct cache_head *cnew,
83 struct cache_head *ckey)
85 struct nfs_dns_ent *new;
86 struct nfs_dns_ent *key;
88 new = container_of(cnew, struct nfs_dns_ent, h);
89 key = container_of(ckey, struct nfs_dns_ent, h);
92 new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
94 new->namelen = key->namelen;
95 nfs_dns_ent_update(cnew, ckey);
102 static void nfs_dns_ent_put(struct kref *ref)
104 struct nfs_dns_ent *item;
106 item = container_of(ref, struct nfs_dns_ent, h.ref);
107 kfree(item->hostname);
111 static struct cache_head *nfs_dns_ent_alloc(void)
113 struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
116 item->hostname = NULL;
124 static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
126 return hash_str(key->hostname, NFS_DNS_HASHBITS);
129 static void nfs_dns_request(struct cache_detail *cd,
130 struct cache_head *ch,
131 char **bpp, int *blen)
133 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
135 qword_add(bpp, blen, key->hostname);
139 static int nfs_dns_upcall(struct cache_detail *cd,
140 struct cache_head *ch)
142 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
145 ret = nfs_cache_upcall(cd, key->hostname);
147 ret = sunrpc_cache_pipe_upcall(cd, ch);
151 static int nfs_dns_match(struct cache_head *ca,
152 struct cache_head *cb)
154 struct nfs_dns_ent *a;
155 struct nfs_dns_ent *b;
157 a = container_of(ca, struct nfs_dns_ent, h);
158 b = container_of(cb, struct nfs_dns_ent, h);
160 if (a->namelen == 0 || a->namelen != b->namelen)
162 return memcmp(a->hostname, b->hostname, a->namelen) == 0;
165 static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
166 struct cache_head *h)
168 struct nfs_dns_ent *item;
172 seq_puts(m, "# ip address hostname ttl\n");
175 item = container_of(h, struct nfs_dns_ent, h);
176 ttl = item->h.expiry_time - seconds_since_boot();
180 if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
181 char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
183 rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
184 seq_printf(m, "%15s ", buf);
186 seq_puts(m, "<none> ");
187 seq_printf(m, "%15s %ld\n", item->hostname, ttl);
191 static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
192 struct nfs_dns_ent *key)
194 struct cache_head *ch;
196 ch = sunrpc_cache_lookup(cd,
201 return container_of(ch, struct nfs_dns_ent, h);
204 static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
205 struct nfs_dns_ent *new,
206 struct nfs_dns_ent *key)
208 struct cache_head *ch;
210 ch = sunrpc_cache_update(cd,
215 return container_of(ch, struct nfs_dns_ent, h);
218 static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
220 char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
221 struct nfs_dns_ent key, *item;
226 if (buf[buflen-1] != '\n')
228 buf[buflen-1] = '\0';
230 len = qword_get(&buf, buf1, sizeof(buf1));
233 key.addrlen = rpc_pton(cd->net, buf1, len,
234 (struct sockaddr *)&key.addr,
237 len = qword_get(&buf, buf1, sizeof(buf1));
243 memset(&key.h, 0, sizeof(key.h));
245 if (get_uint(&buf, &ttl) < 0)
249 key.h.expiry_time = ttl + seconds_since_boot();
252 item = nfs_dns_lookup(cd, &key);
256 if (key.addrlen == 0)
257 set_bit(CACHE_NEGATIVE, &key.h.flags);
259 item = nfs_dns_update(cd, &key, item);
264 cache_put(&item->h, cd);
269 static int do_cache_lookup(struct cache_detail *cd,
270 struct nfs_dns_ent *key,
271 struct nfs_dns_ent **item,
272 struct nfs_cache_defer_req *dreq)
276 *item = nfs_dns_lookup(cd, key);
278 ret = cache_check(cd, &(*item)->h, &dreq->req);
285 static int do_cache_lookup_nowait(struct cache_detail *cd,
286 struct nfs_dns_ent *key,
287 struct nfs_dns_ent **item)
291 *item = nfs_dns_lookup(cd, key);
295 if (!test_bit(CACHE_VALID, &(*item)->h.flags)
296 || (*item)->h.expiry_time < seconds_since_boot()
297 || cd->flush_time > (*item)->h.last_refresh)
300 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
304 cache_put(&(*item)->h, cd);
310 static int do_cache_lookup_wait(struct cache_detail *cd,
311 struct nfs_dns_ent *key,
312 struct nfs_dns_ent **item)
314 struct nfs_cache_defer_req *dreq;
317 dreq = nfs_cache_defer_req_alloc();
320 ret = do_cache_lookup(cd, key, item, dreq);
321 if (ret == -EAGAIN) {
322 ret = nfs_cache_wait_for_upcall(dreq);
324 ret = do_cache_lookup_nowait(cd, key, item);
326 nfs_cache_defer_req_put(dreq);
331 ssize_t nfs_dns_resolve_name(struct net *net, char *name,
332 size_t namelen, struct sockaddr *sa, size_t salen)
334 struct nfs_dns_ent key = {
338 struct nfs_dns_ent *item = NULL;
340 struct nfs_net *nn = net_generic(net, nfs_net_id);
342 ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
344 if (salen >= item->addrlen) {
345 memcpy(sa, &item->addr, item->addrlen);
349 cache_put(&item->h, nn->nfs_dns_resolve);
350 } else if (ret == -ENOENT)
354 EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
356 static struct cache_detail nfs_dns_resolve_template = {
357 .owner = THIS_MODULE,
358 .hash_size = NFS_DNS_HASHTBL_SIZE,
359 .name = "dns_resolve",
360 .cache_put = nfs_dns_ent_put,
361 .cache_upcall = nfs_dns_upcall,
362 .cache_request = nfs_dns_request,
363 .cache_parse = nfs_dns_parse,
364 .cache_show = nfs_dns_show,
365 .match = nfs_dns_match,
366 .init = nfs_dns_ent_init,
367 .update = nfs_dns_ent_update,
368 .alloc = nfs_dns_ent_alloc,
372 int nfs_dns_resolver_cache_init(struct net *net)
375 struct nfs_net *nn = net_generic(net, nfs_net_id);
377 nn->nfs_dns_resolve = cache_create_net(&nfs_dns_resolve_template, net);
378 if (IS_ERR(nn->nfs_dns_resolve))
379 return PTR_ERR(nn->nfs_dns_resolve);
381 err = nfs_cache_register_net(net, nn->nfs_dns_resolve);
387 cache_destroy_net(nn->nfs_dns_resolve, net);
391 void nfs_dns_resolver_cache_destroy(struct net *net)
393 struct nfs_net *nn = net_generic(net, nfs_net_id);
395 nfs_cache_unregister_net(net, nn->nfs_dns_resolve);
396 cache_destroy_net(nn->nfs_dns_resolve, net);
399 static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
402 struct super_block *sb = ptr;
403 struct net *net = sb->s_fs_info;
404 struct nfs_net *nn = net_generic(net, nfs_net_id);
405 struct cache_detail *cd = nn->nfs_dns_resolve;
411 if (!try_module_get(THIS_MODULE))
415 case RPC_PIPEFS_MOUNT:
416 ret = nfs_cache_register_sb(sb, cd);
418 case RPC_PIPEFS_UMOUNT:
419 nfs_cache_unregister_sb(sb, cd);
425 module_put(THIS_MODULE);
429 static struct notifier_block nfs_dns_resolver_block = {
430 .notifier_call = rpc_pipefs_event,
433 int nfs_dns_resolver_init(void)
435 return rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
438 void nfs_dns_resolver_destroy(void)
440 rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);