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e571cbf1 TM |
1 | /* |
2 | * linux/fs/nfs/dns_resolve.c | |
3 | * | |
4 | * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com> | |
5 | * | |
6 | * Resolves DNS hostnames into valid ip addresses | |
7 | */ | |
8 | ||
9 | #include <linux/hash.h> | |
10 | #include <linux/string.h> | |
11 | #include <linux/kmod.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/socket.h> | |
14 | #include <linux/seq_file.h> | |
15 | #include <linux/inet.h> | |
16 | #include <linux/sunrpc/clnt.h> | |
17 | #include <linux/sunrpc/cache.h> | |
18 | #include <linux/sunrpc/svcauth.h> | |
19 | ||
20 | #include "dns_resolve.h" | |
21 | #include "cache_lib.h" | |
22 | ||
23 | #define NFS_DNS_HASHBITS 4 | |
24 | #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS) | |
25 | ||
26 | static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE]; | |
27 | ||
28 | struct nfs_dns_ent { | |
29 | struct cache_head h; | |
30 | ||
31 | char *hostname; | |
32 | size_t namelen; | |
33 | ||
34 | struct sockaddr_storage addr; | |
35 | size_t addrlen; | |
36 | }; | |
37 | ||
38 | ||
39 | static void nfs_dns_ent_init(struct cache_head *cnew, | |
40 | struct cache_head *ckey) | |
41 | { | |
42 | struct nfs_dns_ent *new; | |
43 | struct nfs_dns_ent *key; | |
44 | ||
45 | new = container_of(cnew, struct nfs_dns_ent, h); | |
46 | key = container_of(ckey, struct nfs_dns_ent, h); | |
47 | ||
48 | kfree(new->hostname); | |
49 | new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL); | |
50 | if (new->hostname) { | |
51 | new->namelen = key->namelen; | |
52 | memcpy(&new->addr, &key->addr, key->addrlen); | |
53 | new->addrlen = key->addrlen; | |
54 | } else { | |
55 | new->namelen = 0; | |
56 | new->addrlen = 0; | |
57 | } | |
58 | } | |
59 | ||
60 | static void nfs_dns_ent_put(struct kref *ref) | |
61 | { | |
62 | struct nfs_dns_ent *item; | |
63 | ||
64 | item = container_of(ref, struct nfs_dns_ent, h.ref); | |
65 | kfree(item->hostname); | |
66 | kfree(item); | |
67 | } | |
68 | ||
69 | static struct cache_head *nfs_dns_ent_alloc(void) | |
70 | { | |
71 | struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL); | |
72 | ||
73 | if (item != NULL) { | |
74 | item->hostname = NULL; | |
75 | item->namelen = 0; | |
76 | item->addrlen = 0; | |
77 | return &item->h; | |
78 | } | |
79 | return NULL; | |
80 | }; | |
81 | ||
82 | static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key) | |
83 | { | |
84 | return hash_str(key->hostname, NFS_DNS_HASHBITS); | |
85 | } | |
86 | ||
87 | static void nfs_dns_request(struct cache_detail *cd, | |
88 | struct cache_head *ch, | |
89 | char **bpp, int *blen) | |
90 | { | |
91 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); | |
92 | ||
93 | qword_add(bpp, blen, key->hostname); | |
94 | (*bpp)[-1] = '\n'; | |
95 | } | |
96 | ||
97 | static int nfs_dns_upcall(struct cache_detail *cd, | |
98 | struct cache_head *ch) | |
99 | { | |
100 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); | |
101 | int ret; | |
102 | ||
103 | ret = nfs_cache_upcall(cd, key->hostname); | |
104 | if (ret) | |
105 | ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request); | |
106 | return ret; | |
107 | } | |
108 | ||
109 | static int nfs_dns_match(struct cache_head *ca, | |
110 | struct cache_head *cb) | |
111 | { | |
112 | struct nfs_dns_ent *a; | |
113 | struct nfs_dns_ent *b; | |
114 | ||
115 | a = container_of(ca, struct nfs_dns_ent, h); | |
116 | b = container_of(cb, struct nfs_dns_ent, h); | |
117 | ||
118 | if (a->namelen == 0 || a->namelen != b->namelen) | |
119 | return 0; | |
120 | return memcmp(a->hostname, b->hostname, a->namelen) == 0; | |
121 | } | |
122 | ||
123 | static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd, | |
124 | struct cache_head *h) | |
125 | { | |
126 | struct nfs_dns_ent *item; | |
127 | long ttl; | |
128 | ||
129 | if (h == NULL) { | |
130 | seq_puts(m, "# ip address hostname ttl\n"); | |
131 | return 0; | |
132 | } | |
133 | item = container_of(h, struct nfs_dns_ent, h); | |
134 | ttl = (long)item->h.expiry_time - (long)get_seconds(); | |
135 | if (ttl < 0) | |
136 | ttl = 0; | |
137 | ||
138 | if (!test_bit(CACHE_NEGATIVE, &h->flags)) { | |
139 | char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1]; | |
140 | ||
141 | rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf)); | |
142 | seq_printf(m, "%15s ", buf); | |
143 | } else | |
144 | seq_puts(m, "<none> "); | |
145 | seq_printf(m, "%15s %ld\n", item->hostname, ttl); | |
146 | return 0; | |
147 | } | |
148 | ||
149 | struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd, | |
150 | struct nfs_dns_ent *key) | |
151 | { | |
152 | struct cache_head *ch; | |
153 | ||
154 | ch = sunrpc_cache_lookup(cd, | |
155 | &key->h, | |
156 | nfs_dns_hash(key)); | |
157 | if (!ch) | |
158 | return NULL; | |
159 | return container_of(ch, struct nfs_dns_ent, h); | |
160 | } | |
161 | ||
162 | struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd, | |
163 | struct nfs_dns_ent *new, | |
164 | struct nfs_dns_ent *key) | |
165 | { | |
166 | struct cache_head *ch; | |
167 | ||
168 | ch = sunrpc_cache_update(cd, | |
169 | &new->h, &key->h, | |
170 | nfs_dns_hash(key)); | |
171 | if (!ch) | |
172 | return NULL; | |
173 | return container_of(ch, struct nfs_dns_ent, h); | |
174 | } | |
175 | ||
176 | static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen) | |
177 | { | |
178 | char buf1[NFS_DNS_HOSTNAME_MAXLEN+1]; | |
179 | struct nfs_dns_ent key, *item; | |
180 | unsigned long ttl; | |
181 | ssize_t len; | |
182 | int ret = -EINVAL; | |
183 | ||
184 | if (buf[buflen-1] != '\n') | |
185 | goto out; | |
186 | buf[buflen-1] = '\0'; | |
187 | ||
188 | len = qword_get(&buf, buf1, sizeof(buf1)); | |
189 | if (len <= 0) | |
190 | goto out; | |
191 | key.addrlen = rpc_pton(buf1, len, | |
192 | (struct sockaddr *)&key.addr, | |
193 | sizeof(key.addr)); | |
194 | ||
195 | len = qword_get(&buf, buf1, sizeof(buf1)); | |
196 | if (len <= 0) | |
197 | goto out; | |
198 | ||
199 | key.hostname = buf1; | |
200 | key.namelen = len; | |
201 | memset(&key.h, 0, sizeof(key.h)); | |
202 | ||
203 | ttl = get_expiry(&buf); | |
204 | if (ttl == 0) | |
205 | goto out; | |
206 | key.h.expiry_time = ttl + get_seconds(); | |
207 | ||
208 | ret = -ENOMEM; | |
209 | item = nfs_dns_lookup(cd, &key); | |
210 | if (item == NULL) | |
211 | goto out; | |
212 | ||
213 | if (key.addrlen == 0) | |
214 | set_bit(CACHE_NEGATIVE, &key.h.flags); | |
215 | ||
216 | item = nfs_dns_update(cd, &key, item); | |
217 | if (item == NULL) | |
218 | goto out; | |
219 | ||
220 | ret = 0; | |
221 | cache_put(&item->h, cd); | |
222 | out: | |
223 | return ret; | |
224 | } | |
225 | ||
226 | static struct cache_detail nfs_dns_resolve = { | |
227 | .owner = THIS_MODULE, | |
228 | .hash_size = NFS_DNS_HASHTBL_SIZE, | |
229 | .hash_table = nfs_dns_table, | |
230 | .name = "dns_resolve", | |
231 | .cache_put = nfs_dns_ent_put, | |
232 | .cache_upcall = nfs_dns_upcall, | |
233 | .cache_parse = nfs_dns_parse, | |
234 | .cache_show = nfs_dns_show, | |
235 | .match = nfs_dns_match, | |
236 | .init = nfs_dns_ent_init, | |
237 | .update = nfs_dns_ent_init, | |
238 | .alloc = nfs_dns_ent_alloc, | |
239 | }; | |
240 | ||
241 | static int do_cache_lookup(struct cache_detail *cd, | |
242 | struct nfs_dns_ent *key, | |
243 | struct nfs_dns_ent **item, | |
244 | struct nfs_cache_defer_req *dreq) | |
245 | { | |
246 | int ret = -ENOMEM; | |
247 | ||
248 | *item = nfs_dns_lookup(cd, key); | |
249 | if (*item) { | |
250 | ret = cache_check(cd, &(*item)->h, &dreq->req); | |
251 | if (ret) | |
252 | *item = NULL; | |
253 | } | |
254 | return ret; | |
255 | } | |
256 | ||
257 | static int do_cache_lookup_nowait(struct cache_detail *cd, | |
258 | struct nfs_dns_ent *key, | |
259 | struct nfs_dns_ent **item) | |
260 | { | |
261 | int ret = -ENOMEM; | |
262 | ||
263 | *item = nfs_dns_lookup(cd, key); | |
264 | if (!*item) | |
265 | goto out_err; | |
266 | ret = -ETIMEDOUT; | |
267 | if (!test_bit(CACHE_VALID, &(*item)->h.flags) | |
268 | || (*item)->h.expiry_time < get_seconds() | |
269 | || cd->flush_time > (*item)->h.last_refresh) | |
270 | goto out_put; | |
271 | ret = -ENOENT; | |
272 | if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags)) | |
273 | goto out_put; | |
274 | return 0; | |
275 | out_put: | |
276 | cache_put(&(*item)->h, cd); | |
277 | out_err: | |
278 | *item = NULL; | |
279 | return ret; | |
280 | } | |
281 | ||
282 | static int do_cache_lookup_wait(struct cache_detail *cd, | |
283 | struct nfs_dns_ent *key, | |
284 | struct nfs_dns_ent **item) | |
285 | { | |
286 | struct nfs_cache_defer_req *dreq; | |
287 | int ret = -ENOMEM; | |
288 | ||
289 | dreq = nfs_cache_defer_req_alloc(); | |
290 | if (!dreq) | |
291 | goto out; | |
292 | ret = do_cache_lookup(cd, key, item, dreq); | |
293 | if (ret == -EAGAIN) { | |
294 | ret = nfs_cache_wait_for_upcall(dreq); | |
295 | if (!ret) | |
296 | ret = do_cache_lookup_nowait(cd, key, item); | |
297 | } | |
298 | nfs_cache_defer_req_put(dreq); | |
299 | out: | |
300 | return ret; | |
301 | } | |
302 | ||
303 | ssize_t nfs_dns_resolve_name(char *name, size_t namelen, | |
304 | struct sockaddr *sa, size_t salen) | |
305 | { | |
306 | struct nfs_dns_ent key = { | |
307 | .hostname = name, | |
308 | .namelen = namelen, | |
309 | }; | |
310 | struct nfs_dns_ent *item = NULL; | |
311 | ssize_t ret; | |
312 | ||
313 | ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item); | |
314 | if (ret == 0) { | |
315 | if (salen >= item->addrlen) { | |
316 | memcpy(sa, &item->addr, item->addrlen); | |
317 | ret = item->addrlen; | |
318 | } else | |
319 | ret = -EOVERFLOW; | |
320 | cache_put(&item->h, &nfs_dns_resolve); | |
321 | } else if (ret == -ENOENT) | |
322 | ret = -ESRCH; | |
323 | return ret; | |
324 | } | |
325 | ||
326 | int nfs_dns_resolver_init(void) | |
327 | { | |
328 | return nfs_cache_register(&nfs_dns_resolve); | |
329 | } | |
330 | ||
331 | void nfs_dns_resolver_destroy(void) | |
332 | { | |
333 | nfs_cache_unregister(&nfs_dns_resolve); | |
334 | } | |
335 |