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197c183f SF |
1 | /* |
2 | * fs/cifs/dns_resolve.c | |
3 | * | |
4 | * Copyright (c) 2007 Igor Mammedov | |
5 | * Author(s): Igor Mammedov (niallain@gmail.com) | |
6 | * Steve French (sfrench@us.ibm.com) | |
7 | * | |
8 | * Contains the CIFS DFS upcall routines used for hostname to | |
9 | * IP address translation. | |
10 | * | |
11 | * This library is free software; you can redistribute it and/or modify | |
12 | * it under the terms of the GNU Lesser General Public License as published | |
13 | * by the Free Software Foundation; either version 2.1 of the License, or | |
14 | * (at your option) any later version. | |
15 | * | |
16 | * This library is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See | |
19 | * the GNU Lesser General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU Lesser General Public License | |
22 | * along with this library; if not, write to the Free Software | |
23 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
24 | */ | |
25 | ||
26 | #include <keys/user-type.h> | |
27 | #include "dns_resolve.h" | |
28 | #include "cifsglob.h" | |
29 | #include "cifsproto.h" | |
30 | #include "cifs_debug.h" | |
31 | ||
32 | static int dns_resolver_instantiate(struct key *key, const void *data, | |
33 | size_t datalen) | |
34 | { | |
35 | int rc = 0; | |
36 | char *ip; | |
37 | ||
38 | ip = kmalloc(datalen+1, GFP_KERNEL); | |
39 | if (!ip) | |
40 | return -ENOMEM; | |
41 | ||
42 | memcpy(ip, data, datalen); | |
43 | ip[datalen] = '\0'; | |
44 | ||
45 | rcu_assign_pointer(key->payload.data, ip); | |
46 | ||
47 | return rc; | |
48 | } | |
49 | ||
50 | struct key_type key_type_dns_resolver = { | |
51 | .name = "dns_resolver", | |
52 | .def_datalen = sizeof(struct in_addr), | |
53 | .describe = user_describe, | |
54 | .instantiate = dns_resolver_instantiate, | |
55 | .match = user_match, | |
56 | }; | |
57 | ||
58 | ||
59 | /* Resolves server name to ip address. | |
60 | * input: | |
61 | * unc - server UNC | |
62 | * output: | |
63 | * *ip_addr - pointer to server ip, caller responcible for freeing it. | |
64 | * return 0 on success | |
65 | */ | |
66 | int | |
366781c1 SF |
67 | dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) |
68 | { | |
197c183f SF |
69 | int rc = -EAGAIN; |
70 | struct key *rkey; | |
71 | char *name; | |
72 | int len; | |
73 | ||
366781c1 | 74 | if (!ip_addr || !unc) |
197c183f SF |
75 | return -EINVAL; |
76 | ||
77 | /* search for server name delimiter */ | |
78 | len = strlen(unc); | |
79 | if (len < 3) { | |
55f78e17 | 80 | cFYI(1, ("%s: unc is too short: %s", __func__, unc)); |
197c183f SF |
81 | return -EINVAL; |
82 | } | |
83 | len -= 2; | |
84 | name = memchr(unc+2, '\\', len); | |
85 | if (!name) { | |
86 | cFYI(1, ("%s: probably server name is whole unc: %s", | |
55f78e17 | 87 | __func__, unc)); |
197c183f SF |
88 | } else { |
89 | len = (name - unc) - 2/* leading // */; | |
90 | } | |
91 | ||
92 | name = kmalloc(len+1, GFP_KERNEL); | |
93 | if (!name) { | |
94 | rc = -ENOMEM; | |
95 | return rc; | |
96 | } | |
97 | memcpy(name, unc+2, len); | |
98 | name[len] = 0; | |
99 | ||
100 | rkey = request_key(&key_type_dns_resolver, name, ""); | |
101 | if (!IS_ERR(rkey)) { | |
102 | len = strlen(rkey->payload.data); | |
103 | *ip_addr = kmalloc(len+1, GFP_KERNEL); | |
104 | if (*ip_addr) { | |
105 | memcpy(*ip_addr, rkey->payload.data, len); | |
106 | (*ip_addr)[len] = '\0'; | |
55f78e17 | 107 | cFYI(1, ("%s: resolved: %s to %s", __func__, |
197c183f SF |
108 | rkey->description, |
109 | *ip_addr | |
110 | )); | |
111 | rc = 0; | |
112 | } else { | |
113 | rc = -ENOMEM; | |
114 | } | |
115 | key_put(rkey); | |
116 | } else { | |
55f78e17 | 117 | cERROR(1, ("%s: unable to resolve: %s", __func__, name)); |
197c183f SF |
118 | } |
119 | ||
120 | kfree(name); | |
121 | return rc; | |
122 | } | |
123 | ||
124 |