[linux-block.git] / fs / nfs / dns_resolve.c

/*
 * linux/fs/nfs/dns_resolve.c
 *
 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
 *
 * Resolves DNS hostnames into valid ip addresses
 */

#include <linux/hash.h>
#include <linux/string.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/seq_file.h>
#include <linux/inet.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/cache.h>
#include <linux/sunrpc/svcauth.h>

#include "dns_resolve.h"
#include "cache_lib.h"

#define NFS_DNS_HASHBITS 4
#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)

static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];

struct nfs_dns_ent {
	struct cache_head h;

	char *hostname;
	size_t namelen;

	struct sockaddr_storage addr;
	size_t addrlen;
};


static void nfs_dns_ent_update(struct cache_head *cnew,
		struct cache_head *ckey)
{
	struct nfs_dns_ent *new;
	struct nfs_dns_ent *key;

	new = container_of(cnew, struct nfs_dns_ent, h);
	key = container_of(ckey, struct nfs_dns_ent, h);

	memcpy(&new->addr, &key->addr, key->addrlen);
	new->addrlen = key->addrlen;
}

static void nfs_dns_ent_init(struct cache_head *cnew,
		struct cache_head *ckey)
{
	struct nfs_dns_ent *new;
	struct nfs_dns_ent *key;

	new = container_of(cnew, struct nfs_dns_ent, h);
	key = container_of(ckey, struct nfs_dns_ent, h);

	kfree(new->hostname);
	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
	if (new->hostname) {
		new->namelen = key->namelen;
		nfs_dns_ent_update(cnew, ckey);
	} else {
		new->namelen = 0;
		new->addrlen = 0;
	}
}

static void nfs_dns_ent_put(struct kref *ref)
{
	struct nfs_dns_ent *item;

	item = container_of(ref, struct nfs_dns_ent, h.ref);
	kfree(item->hostname);
	kfree(item);
}

static struct cache_head *nfs_dns_ent_alloc(void)
{
	struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);

	if (item != NULL) {
		item->hostname = NULL;
		item->namelen = 0;
		item->addrlen = 0;
		return &item->h;
	}
	return NULL;
};

static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
{
	return hash_str(key->hostname, NFS_DNS_HASHBITS);
}

static void nfs_dns_request(struct cache_detail *cd,
		struct cache_head *ch,
		char **bpp, int *blen)
{
	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);

	qword_add(bpp, blen, key->hostname);
	(*bpp)[-1] = '\n';
}

static int nfs_dns_upcall(struct cache_detail *cd,
		struct cache_head *ch)
{
	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	int ret;

	ret = nfs_cache_upcall(cd, key->hostname);
	if (ret)
		ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
	return ret;
}

static int nfs_dns_match(struct cache_head *ca,
		struct cache_head *cb)
{
	struct nfs_dns_ent *a;
	struct nfs_dns_ent *b;

	a = container_of(ca, struct nfs_dns_ent, h);
	b = container_of(cb, struct nfs_dns_ent, h);

	if (a->namelen == 0 || a->namelen != b->namelen)
		return 0;
	return memcmp(a->hostname, b->hostname, a->namelen) == 0;
}

static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
		struct cache_head *h)
{
	struct nfs_dns_ent *item;
	long ttl;

	if (h == NULL) {
		seq_puts(m, "# ip address      hostname        ttl\n");
		return 0;
	}
	item = container_of(h, struct nfs_dns_ent, h);
	ttl = (long)item->h.expiry_time - (long)get_seconds();
	if (ttl < 0)
		ttl = 0;

	if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
		char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];

		rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
		seq_printf(m, "%15s ", buf);
	} else
		seq_puts(m, "<none>          ");
	seq_printf(m, "%15s %ld\n", item->hostname, ttl);
	return 0;
}

static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
		struct nfs_dns_ent *key)
{
	struct cache_head *ch;

	ch = sunrpc_cache_lookup(cd,
			&key->h,
			nfs_dns_hash(key));
	if (!ch)
		return NULL;
	return container_of(ch, struct nfs_dns_ent, h);
}

static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
		struct nfs_dns_ent *new,
		struct nfs_dns_ent *key)
{
	struct cache_head *ch;

	ch = sunrpc_cache_update(cd,
			&new->h, &key->h,
			nfs_dns_hash(key));
	if (!ch)
		return NULL;
	return container_of(ch, struct nfs_dns_ent, h);
}

static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
{
	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
	struct nfs_dns_ent key, *item;
	unsigned long ttl;
	ssize_t len;
	int ret = -EINVAL;

	if (buf[buflen-1] != '\n')
		goto out;
	buf[buflen-1] = '\0';

	len = qword_get(&buf, buf1, sizeof(buf1));
	if (len <= 0)
		goto out;
	key.addrlen = rpc_pton(buf1, len,
			(struct sockaddr *)&key.addr,
			sizeof(key.addr));

	len = qword_get(&buf, buf1, sizeof(buf1));
	if (len <= 0)
		goto out;

	key.hostname = buf1;
	key.namelen = len;
	memset(&key.h, 0, sizeof(key.h));

	ttl = get_expiry(&buf);
	if (ttl == 0)
		goto out;
	key.h.expiry_time = ttl + get_seconds();

	ret = -ENOMEM;
	item = nfs_dns_lookup(cd, &key);
	if (item == NULL)
		goto out;

	if (key.addrlen == 0)
		set_bit(CACHE_NEGATIVE, &key.h.flags);

	item = nfs_dns_update(cd, &key, item);
	if (item == NULL)
		goto out;

	ret = 0;
	cache_put(&item->h, cd);
out:
	return ret;
}

static struct cache_detail nfs_dns_resolve = {
	.owner = THIS_MODULE,
	.hash_size = NFS_DNS_HASHTBL_SIZE,
	.hash_table = nfs_dns_table,
	.name = "dns_resolve",
	.cache_put = nfs_dns_ent_put,
	.cache_upcall = nfs_dns_upcall,
	.cache_parse = nfs_dns_parse,
	.cache_show = nfs_dns_show,
	.match = nfs_dns_match,
	.init = nfs_dns_ent_init,
	.update = nfs_dns_ent_update,
	.alloc = nfs_dns_ent_alloc,
};

static int do_cache_lookup(struct cache_detail *cd,
		struct nfs_dns_ent *key,
		struct nfs_dns_ent **item,
		struct nfs_cache_defer_req *dreq)
{
	int ret = -ENOMEM;

	*item = nfs_dns_lookup(cd, key);
	if (*item) {
		ret = cache_check(cd, &(*item)->h, &dreq->req);
		if (ret)
			*item = NULL;
	}
	return ret;
}

static int do_cache_lookup_nowait(struct cache_detail *cd,
		struct nfs_dns_ent *key,
		struct nfs_dns_ent **item)
{
	int ret = -ENOMEM;

	*item = nfs_dns_lookup(cd, key);
	if (!*item)
		goto out_err;
	ret = -ETIMEDOUT;
	if (!test_bit(CACHE_VALID, &(*item)->h.flags)
			|| (*item)->h.expiry_time < get_seconds()
			|| cd->flush_time > (*item)->h.last_refresh)
		goto out_put;
	ret = -ENOENT;
	if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
		goto out_put;
	return 0;
out_put:
	cache_put(&(*item)->h, cd);
out_err:
	*item = NULL;
	return ret;
}

static int do_cache_lookup_wait(struct cache_detail *cd,
		struct nfs_dns_ent *key,
		struct nfs_dns_ent **item)
{
	struct nfs_cache_defer_req *dreq;
	int ret = -ENOMEM;

	dreq = nfs_cache_defer_req_alloc();
	if (!dreq)
		goto out;
	ret = do_cache_lookup(cd, key, item, dreq);
	if (ret == -EAGAIN) {
		ret = nfs_cache_wait_for_upcall(dreq);
		if (!ret)
			ret = do_cache_lookup_nowait(cd, key, item);
	}
	nfs_cache_defer_req_put(dreq);
out:
	return ret;
}

ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
		struct sockaddr *sa, size_t salen)
{
	struct nfs_dns_ent key = {
		.hostname = name,
		.namelen = namelen,
	};
	struct nfs_dns_ent *item = NULL;
	ssize_t ret;

	ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
	if (ret == 0) {
		if (salen >= item->addrlen) {
			memcpy(sa, &item->addr, item->addrlen);
			ret = item->addrlen;
		} else
			ret = -EOVERFLOW;
		cache_put(&item->h, &nfs_dns_resolve);
	} else if (ret == -ENOENT)
		ret = -ESRCH;
	return ret;
}

int nfs_dns_resolver_init(void)
{
	return nfs_cache_register(&nfs_dns_resolve);
}

void nfs_dns_resolver_destroy(void)
{
	nfs_cache_unregister(&nfs_dns_resolve);
}
Commit	Line	Data
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>
5a0e3ad6	12	#include <linux/slab.h>
e571cbf1 TM	13	#include <linux/module.h>
	14	#include <linux/socket.h>
	15	#include <linux/seq_file.h>
	16	#include <linux/inet.h>
	17	#include <linux/sunrpc/clnt.h>
	18	#include <linux/sunrpc/cache.h>
	19	#include <linux/sunrpc/svcauth.h>
	20
	21	#include "dns_resolve.h"
	22	#include "cache_lib.h"
	23
	24	#define NFS_DNS_HASHBITS 4
	25	#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
	26
	27	static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];
	28
	29	struct nfs_dns_ent {
	30	struct cache_head h;
	31
	32	char *hostname;
	33	size_t namelen;
	34
	35	struct sockaddr_storage addr;
	36	size_t addrlen;
	37	};
	38
	39
ebed9203 TM	40	static void nfs_dns_ent_update(struct cache_head *cnew,
	41	struct cache_head *ckey)
	42	{
	43	struct nfs_dns_ent *new;
	44	struct nfs_dns_ent *key;
	45
	46	new = container_of(cnew, struct nfs_dns_ent, h);
	47	key = container_of(ckey, struct nfs_dns_ent, h);
	48
	49	memcpy(&new->addr, &key->addr, key->addrlen);
	50	new->addrlen = key->addrlen;
	51	}
	52
e571cbf1 TM	53	static void nfs_dns_ent_init(struct cache_head *cnew,
	54	struct cache_head *ckey)
	55	{
	56	struct nfs_dns_ent *new;
	57	struct nfs_dns_ent *key;
	58
	59	new = container_of(cnew, struct nfs_dns_ent, h);
	60	key = container_of(ckey, struct nfs_dns_ent, h);
	61
	62	kfree(new->hostname);
	63	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
	64	if (new->hostname) {
	65	new->namelen = key->namelen;
ebed9203	66	nfs_dns_ent_update(cnew, ckey);
e571cbf1 TM	67	} else {
	68	new->namelen = 0;
	69	new->addrlen = 0;
	70	}
	71	}
	72
	73	static void nfs_dns_ent_put(struct kref *ref)
	74	{
	75	struct nfs_dns_ent *item;
	76
	77	item = container_of(ref, struct nfs_dns_ent, h.ref);
	78	kfree(item->hostname);
	79	kfree(item);
	80	}
	81
	82	static struct cache_head *nfs_dns_ent_alloc(void)
	83	{
	84	struct nfs_dns_ent item = kmalloc(sizeof(item), GFP_KERNEL);
	85
	86	if (item != NULL) {
	87	item->hostname = NULL;
	88	item->namelen = 0;
	89	item->addrlen = 0;
	90	return &item->h;
	91	}
	92	return NULL;
	93	};
	94
	95	static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
	96	{
	97	return hash_str(key->hostname, NFS_DNS_HASHBITS);
	98	}
	99
	100	static void nfs_dns_request(struct cache_detail *cd,
	101	struct cache_head *ch,
	102	char *bpp, int blen)
	103	{
	104	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	105
	106	qword_add(bpp, blen, key->hostname);
	107	(*bpp)[-1] = '\n';
	108	}
	109
	110	static int nfs_dns_upcall(struct cache_detail *cd,
	111	struct cache_head *ch)
	112	{
	113	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	114	int ret;
	115
	116	ret = nfs_cache_upcall(cd, key->hostname);
	117	if (ret)
	118	ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
	119	return ret;
	120	}
	121
	122	static int nfs_dns_match(struct cache_head *ca,
	123	struct cache_head *cb)
	124	{
	125	struct nfs_dns_ent *a;
	126	struct nfs_dns_ent *b;
	127
	128	a = container_of(ca, struct nfs_dns_ent, h);
	129	b = container_of(cb, struct nfs_dns_ent, h);
	130
131	if (a->namelen == 0 \|\| a->namelen != b->namelen)
132	return 0;
133	return memcmp(a->hostname, b->hostname, a->namelen) == 0;
134	}
135
136	static int nfs_dns_show(struct seq_file m, struct cache_detail cd,
137	struct cache_head *h)
138	{
139	struct nfs_dns_ent *item;
140	long ttl;
141
142	if (h == NULL) {
143	seq_puts(m, "# ip address hostname ttl\n");
144	return 0;
145	}
146	item = container_of(h, struct nfs_dns_ent, h);
147	ttl = (long)item->h.expiry_time - (long)get_seconds();
148	if (ttl < 0)
149	ttl = 0;
150
151	if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
152	char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
153
154	rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
155	seq_printf(m, "%15s ", buf);
156	} else
157	seq_puts(m, "<none> ");
158	seq_printf(m, "%15s %ld\n", item->hostname, ttl);
159	return 0;
160	}
161
0a6566ec	162	static struct nfs_dns_ent nfs_dns_lookup(struct cache_detail cd,
e571cbf1 TM	163	struct nfs_dns_ent *key)
	164	{
	165	struct cache_head *ch;
	166
	167	ch = sunrpc_cache_lookup(cd,
	168	&key->h,
	169	nfs_dns_hash(key));
	170	if (!ch)
	171	return NULL;
	172	return container_of(ch, struct nfs_dns_ent, h);
	173	}
	174
0a6566ec	175	static struct nfs_dns_ent nfs_dns_update(struct cache_detail cd,
e571cbf1 TM	176	struct nfs_dns_ent *new,
	177	struct nfs_dns_ent *key)
	178	{
	179	struct cache_head *ch;
	180
	181	ch = sunrpc_cache_update(cd,
	182	&new->h, &key->h,
	183	nfs_dns_hash(key));
	184	if (!ch)
	185	return NULL;
	186	return container_of(ch, struct nfs_dns_ent, h);
	187	}
	188
	189	static int nfs_dns_parse(struct cache_detail cd, char buf, int buflen)
	190	{
	191	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
	192	struct nfs_dns_ent key, *item;
	193	unsigned long ttl;
	194	ssize_t len;
	195	int ret = -EINVAL;
	196
	197	if (buf[buflen-1] != '\n')
	198	goto out;
	199	buf[buflen-1] = '\0';
	200
	201	len = qword_get(&buf, buf1, sizeof(buf1));
	202	if (len <= 0)
	203	goto out;
	204	key.addrlen = rpc_pton(buf1, len,
	205	(struct sockaddr *)&key.addr,
	206	sizeof(key.addr));
	207
	208	len = qword_get(&buf, buf1, sizeof(buf1));
	209	if (len <= 0)
	210	goto out;
	211
	212	key.hostname = buf1;
	213	key.namelen = len;
	214	memset(&key.h, 0, sizeof(key.h));
	215
	216	ttl = get_expiry(&buf);
	217	if (ttl == 0)
	218	goto out;
	219	key.h.expiry_time = ttl + get_seconds();
	220
	221	ret = -ENOMEM;
	222	item = nfs_dns_lookup(cd, &key);
	223	if (item == NULL)
	224	goto out;
	225
	226	if (key.addrlen == 0)
	227	set_bit(CACHE_NEGATIVE, &key.h.flags);
	228
	229	item = nfs_dns_update(cd, &key, item);
	230	if (item == NULL)
	231	goto out;
	232
	233	ret = 0;
	234	cache_put(&item->h, cd);
	235	out:
	236	return ret;
	237	}
	238
	239	static struct cache_detail nfs_dns_resolve = {
240	.owner = THIS_MODULE,
241	.hash_size = NFS_DNS_HASHTBL_SIZE,
242	.hash_table = nfs_dns_table,
243	.name = "dns_resolve",
244	.cache_put = nfs_dns_ent_put,
245	.cache_upcall = nfs_dns_upcall,
246	.cache_parse = nfs_dns_parse,
247	.cache_show = nfs_dns_show,
248	.match = nfs_dns_match,
249	.init = nfs_dns_ent_init,
ebed9203	250	.update = nfs_dns_ent_update,
e571cbf1 TM	251	.alloc = nfs_dns_ent_alloc,
	252	};
	253
	254	static int do_cache_lookup(struct cache_detail *cd,
	255	struct nfs_dns_ent *key,
	256	struct nfs_dns_ent **item,
	257	struct nfs_cache_defer_req *dreq)
	258	{
	259	int ret = -ENOMEM;
	260
	261	*item = nfs_dns_lookup(cd, key);
	262	if (*item) {
	263	ret = cache_check(cd, &(*item)->h, &dreq->req);
	264	if (ret)
	265	*item = NULL;
	266	}
	267	return ret;
	268	}
	269
	270	static int do_cache_lookup_nowait(struct cache_detail *cd,
	271	struct nfs_dns_ent *key,
	272	struct nfs_dns_ent **item)
	273	{
	274	int ret = -ENOMEM;
	275
	276	*item = nfs_dns_lookup(cd, key);
	277	if (!*item)
	278	goto out_err;
	279	ret = -ETIMEDOUT;
	280	if (!test_bit(CACHE_VALID, &(*item)->h.flags)
	281	\|\| (*item)->h.expiry_time < get_seconds()
	282	\|\| cd->flush_time > (*item)->h.last_refresh)
	283	goto out_put;
	284	ret = -ENOENT;
	285	if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
	286	goto out_put;
	287	return 0;
	288	out_put:
	289	cache_put(&(*item)->h, cd);
	290	out_err:
	291	*item = NULL;
	292	return ret;
	293	}
	294
	295	static int do_cache_lookup_wait(struct cache_detail *cd,
	296	struct nfs_dns_ent *key,
	297	struct nfs_dns_ent **item)
	298	{
	299	struct nfs_cache_defer_req *dreq;
	300	int ret = -ENOMEM;
	301
	302	dreq = nfs_cache_defer_req_alloc();
	303	if (!dreq)
	304	goto out;
	305	ret = do_cache_lookup(cd, key, item, dreq);
	306	if (ret == -EAGAIN) {
	307	ret = nfs_cache_wait_for_upcall(dreq);
	308	if (!ret)
	309	ret = do_cache_lookup_nowait(cd, key, item);
	310	}
	311	nfs_cache_defer_req_put(dreq);
	312	out:
	313	return ret;
	314	}
315
316	ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
317	struct sockaddr *sa, size_t salen)
318	{
319	struct nfs_dns_ent key = {
320	.hostname = name,
321	.namelen = namelen,
322	};
323	struct nfs_dns_ent *item = NULL;
324	ssize_t ret;
325
326	ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
327	if (ret == 0) {
328	if (salen >= item->addrlen) {
329	memcpy(sa, &item->addr, item->addrlen);
330	ret = item->addrlen;
331	} else
332	ret = -EOVERFLOW;
333	cache_put(&item->h, &nfs_dns_resolve);
334	} else if (ret == -ENOENT)
335	ret = -ESRCH;
336	return ret;
337	}
338
339	int nfs_dns_resolver_init(void)
340	{
341	return nfs_cache_register(&nfs_dns_resolve);
342	}
343
344	void nfs_dns_resolver_destroy(void)
345	{
346	nfs_cache_unregister(&nfs_dns_resolve);
347	}
348