1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
// SPDX-License-Identifier: LGPL-2.1
/*
*
* Copyright (c) 2007 Igor Mammedov
* Author(s): Igor Mammedov (niallain@gmail.com)
* Steve French (sfrench@us.ibm.com)
* Wang Lei (wang840925@gmail.com)
* David Howells (dhowells@redhat.com)
*
* Contains the CIFS DFS upcall routines used for hostname to
* IP address translation.
*
*/
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/dns_resolver.h>
#include "dns_resolve.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
/**
* dns_resolve_server_name_to_ip - Resolve UNC server name to ip address.
* @unc: UNC path specifying the server (with '/' as delimiter)
* @ip_addr: Where to return the IP address.
* @expiry: Where to return the expiry time for the dns record.
*
* Returns zero success, -ve on error.
*/
int
dns_resolve_server_name_to_ip(const char *unc, struct sockaddr *ip_addr, time64_t *expiry)
{
const char *hostname, *sep;
char *ip;
int len, rc;
if (!ip_addr || !unc)
return -EINVAL;
len = strlen(unc);
if (len < 3) {
cifs_dbg(FYI, "%s: unc is too short: %s\n", __func__, unc);
return -EINVAL;
}
/* Discount leading slashes for cifs */
len -= 2;
hostname = unc + 2;
/* Search for server name delimiter */
sep = memchr(hostname, '/', len);
if (sep)
len = sep - hostname;
else
cifs_dbg(FYI, "%s: probably server name is whole unc: %s\n",
__func__, unc);
/* Try to interpret hostname as an IPv4 or IPv6 address */
rc = cifs_convert_address(ip_addr, hostname, len);
if (rc > 0) {
cifs_dbg(FYI, "%s: unc is IP, skipping dns upcall: %*.*s\n", __func__, len, len,
hostname);
return 0;
}
/* Perform the upcall */
rc = dns_query(current->nsproxy->net_ns, NULL, hostname, len,
NULL, &ip, expiry, false);
if (rc < 0) {
cifs_dbg(FYI, "%s: unable to resolve: %*.*s\n",
__func__, len, len, hostname);
} else {
cifs_dbg(FYI, "%s: resolved: %*.*s to %s expiry %llu\n",
__func__, len, len, hostname, ip,
expiry ? (*expiry) : 0);
rc = cifs_convert_address(ip_addr, ip, strlen(ip));
kfree(ip);
if (!rc) {
cifs_dbg(FYI, "%s: unable to determine ip address\n", __func__);
rc = -EHOSTUNREACH;
} else
rc = 0;
}
return rc;
}
|
