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9#ifdef CONFIG_NFS_USE_KERNEL_DNS
10
11#include <linux/sunrpc/clnt.h>
12#include <linux/dns_resolver.h>
13
14ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
15 struct sockaddr *sa, size_t salen)
16{
17 ssize_t ret;
18 char *ip_addr = NULL;
19 int ip_len;
20
21 ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
22 if (ip_len > 0)
23 ret = rpc_pton(ip_addr, ip_len, sa, salen);
24 else
25 ret = -ESRCH;
26 kfree(ip_addr);
27 return ret;
28}
29
30#else
31
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>
43
44#include "dns_resolve.h"
45#include "cache_lib.h"
46
47#define NFS_DNS_HASHBITS 4
48#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
49
50static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];
51
52struct nfs_dns_ent {
53 struct cache_head h;
54
55 char *hostname;
56 size_t namelen;
57
58 struct sockaddr_storage addr;
59 size_t addrlen;
60};
61
62
63static void nfs_dns_ent_update(struct cache_head *cnew,
64 struct cache_head *ckey)
65{
66 struct nfs_dns_ent *new;
67 struct nfs_dns_ent *key;
68
69 new = container_of(cnew, struct nfs_dns_ent, h);
70 key = container_of(ckey, struct nfs_dns_ent, h);
71
72 memcpy(&new->addr, &key->addr, key->addrlen);
73 new->addrlen = key->addrlen;
74}
75
76static void nfs_dns_ent_init(struct cache_head *cnew,
77 struct cache_head *ckey)
78{
79 struct nfs_dns_ent *new;
80 struct nfs_dns_ent *key;
81
82 new = container_of(cnew, struct nfs_dns_ent, h);
83 key = container_of(ckey, struct nfs_dns_ent, h);
84
85 kfree(new->hostname);
86 new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
87 if (new->hostname) {
88 new->namelen = key->namelen;
89 nfs_dns_ent_update(cnew, ckey);
90 } else {
91 new->namelen = 0;
92 new->addrlen = 0;
93 }
94}
95
96static void nfs_dns_ent_put(struct kref *ref)
97{
98 struct nfs_dns_ent *item;
99
100 item = container_of(ref, struct nfs_dns_ent, h.ref);
101 kfree(item->hostname);
102 kfree(item);
103}
104
105static struct cache_head *nfs_dns_ent_alloc(void)
106{
107 struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
108
109 if (item != NULL) {
110 item->hostname = NULL;
111 item->namelen = 0;
112 item->addrlen = 0;
113 return &item->h;
114 }
115 return NULL;
116};
117
118static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
119{
120 return hash_str(key->hostname, NFS_DNS_HASHBITS);
121}
122
123static void nfs_dns_request(struct cache_detail *cd,
124 struct cache_head *ch,
125 char **bpp, int *blen)
126{
127 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
128
129 qword_add(bpp, blen, key->hostname);
130 (*bpp)[-1] = '\n';
131}
132
133static int nfs_dns_upcall(struct cache_detail *cd,
134 struct cache_head *ch)
135{
136 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
137 int ret;
138
139 ret = nfs_cache_upcall(cd, key->hostname);
140 if (ret)
141 ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
142 return ret;
143}
144
145static int nfs_dns_match(struct cache_head *ca,
146 struct cache_head *cb)
147{
148 struct nfs_dns_ent *a;
149 struct nfs_dns_ent *b;
150
151 a = container_of(ca, struct nfs_dns_ent, h);
152 b = container_of(cb, struct nfs_dns_ent, h);
153
154 if (a->namelen == 0 || a->namelen != b->namelen)
155 return 0;
156 return memcmp(a->hostname, b->hostname, a->namelen) == 0;
157}
158
159static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
160 struct cache_head *h)
161{
162 struct nfs_dns_ent *item;
163 long ttl;
164
165 if (h == NULL) {
166 seq_puts(m, "# ip address hostname ttl\n");
167 return 0;
168 }
169 item = container_of(h, struct nfs_dns_ent, h);
170 ttl = item->h.expiry_time - seconds_since_boot();
171 if (ttl < 0)
172 ttl = 0;
173
174 if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
175 char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
176
177 rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
178 seq_printf(m, "%15s ", buf);
179 } else
180 seq_puts(m, "<none> ");
181 seq_printf(m, "%15s %ld\n", item->hostname, ttl);
182 return 0;
183}
184
185static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
186 struct nfs_dns_ent *key)
187{
188 struct cache_head *ch;
189
190 ch = sunrpc_cache_lookup(cd,
191 &key->h,
192 nfs_dns_hash(key));
193 if (!ch)
194 return NULL;
195 return container_of(ch, struct nfs_dns_ent, h);
196}
197
198static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
199 struct nfs_dns_ent *new,
200 struct nfs_dns_ent *key)
201{
202 struct cache_head *ch;
203
204 ch = sunrpc_cache_update(cd,
205 &new->h, &key->h,
206 nfs_dns_hash(key));
207 if (!ch)
208 return NULL;
209 return container_of(ch, struct nfs_dns_ent, h);
210}
211
212static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
213{
214 char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
215 struct nfs_dns_ent key, *item;
216 unsigned long ttl;
217 ssize_t len;
218 int ret = -EINVAL;
219
220 if (buf[buflen-1] != '\n')
221 goto out;
222 buf[buflen-1] = '\0';
223
224 len = qword_get(&buf, buf1, sizeof(buf1));
225 if (len <= 0)
226 goto out;
227 key.addrlen = rpc_pton(buf1, len,
228 (struct sockaddr *)&key.addr,
229 sizeof(key.addr));
230
231 len = qword_get(&buf, buf1, sizeof(buf1));
232 if (len <= 0)
233 goto out;
234
235 key.hostname = buf1;
236 key.namelen = len;
237 memset(&key.h, 0, sizeof(key.h));
238
239 ttl = get_expiry(&buf);
240 if (ttl == 0)
241 goto out;
242 key.h.expiry_time = ttl + seconds_since_boot();
243
244 ret = -ENOMEM;
245 item = nfs_dns_lookup(cd, &key);
246 if (item == NULL)
247 goto out;
248
249 if (key.addrlen == 0)
250 set_bit(CACHE_NEGATIVE, &key.h.flags);
251
252 item = nfs_dns_update(cd, &key, item);
253 if (item == NULL)
254 goto out;
255
256 ret = 0;
257 cache_put(&item->h, cd);
258out:
259 return ret;
260}
261
262static 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,
275};
276
277static 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)
281{
282 int ret = -ENOMEM;
283
284 *item = nfs_dns_lookup(cd, key);
285 if (*item) {
286 ret = cache_check(cd, &(*item)->h, &dreq->req);
287 if (ret)
288 *item = NULL;
289 }
290 return ret;
291}
292
293static int do_cache_lookup_nowait(struct cache_detail *cd,
294 struct nfs_dns_ent *key,
295 struct nfs_dns_ent **item)
296{
297 int ret = -ENOMEM;
298
299 *item = nfs_dns_lookup(cd, key);
300 if (!*item)
301 goto out_err;
302 ret = -ETIMEDOUT;
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)
306 goto out_put;
307 ret = -ENOENT;
308 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
309 goto out_put;
310 return 0;
311out_put:
312 cache_put(&(*item)->h, cd);
313out_err:
314 *item = NULL;
315 return ret;
316}
317
318static int do_cache_lookup_wait(struct cache_detail *cd,
319 struct nfs_dns_ent *key,
320 struct nfs_dns_ent **item)
321{
322 struct nfs_cache_defer_req *dreq;
323 int ret = -ENOMEM;
324
325 dreq = nfs_cache_defer_req_alloc();
326 if (!dreq)
327 goto out;
328 ret = do_cache_lookup(cd, key, item, dreq);
329 if (ret == -EAGAIN) {
330 ret = nfs_cache_wait_for_upcall(dreq);
331 if (!ret)
332 ret = do_cache_lookup_nowait(cd, key, item);
333 }
334 nfs_cache_defer_req_put(dreq);
335out:
336 return ret;
337}
338
339ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
340 struct sockaddr *sa, size_t salen)
341{
342 struct nfs_dns_ent key = {
343 .hostname = name,
344 .namelen = namelen,
345 };
346 struct nfs_dns_ent *item = NULL;
347 ssize_t ret;
348
349 ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
350 if (ret == 0) {
351 if (salen >= item->addrlen) {
352 memcpy(sa, &item->addr, item->addrlen);
353 ret = item->addrlen;
354 } else
355 ret = -EOVERFLOW;
356 cache_put(&item->h, &nfs_dns_resolve);
357 } else if (ret == -ENOENT)
358 ret = -ESRCH;
359 return ret;
360}
361
362int nfs_dns_resolver_init(void)
363{
364 return nfs_cache_register(&nfs_dns_resolve);
365}
366
367void nfs_dns_resolver_destroy(void)
368{
369 nfs_cache_unregister(&nfs_dns_resolve);
370}
371
372#endif
373
