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);