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
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
/* Copyright (C) 2004-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <not-cancel.h>
#include "nscd-client.h"
#include "nscd_proto.h"
/* Define in nscd_gethst_r.c. */
extern int __nss_not_use_nscd_hosts;
/* We use the mapping from nscd_gethst. */
libc_locked_map_ptr (extern, __hst_map_handle) attribute_hidden;
/* Defined in nscd_gethst_r.c. */
extern int __nss_have_localdomain attribute_hidden;
int
__nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
{
if (__glibc_unlikely (__nss_have_localdomain >= 0))
{
if (__nss_have_localdomain == 0)
__nss_have_localdomain = getenv ("LOCALDOMAIN") != NULL ? 1 : -1;
if (__nss_have_localdomain > 0)
{
__nss_not_use_nscd_hosts = 1;
return -1;
}
}
size_t keylen = strlen (key) + 1;
int gc_cycle;
int nretries = 0;
/* If the mapping is available, try to search there instead of
communicating with the nscd. */
struct mapped_database *mapped;
mapped = __nscd_get_map_ref (GETFDHST, "hosts", &__hst_map_handle,
&gc_cycle);
retry:;
struct nscd_ai_result *resultbuf = NULL;
const char *recend = (const char *) ~UINTMAX_C (0);
char *respdata = NULL;
int retval = -1;
int sock = -1;
ai_response_header ai_resp;
if (mapped != NO_MAPPING)
{
struct datahead *found = __nscd_cache_search (GETAI, key, keylen,
mapped, sizeof ai_resp);
if (found != NULL)
{
respdata = (char *) (&found->data[0].aidata + 1);
ai_resp = found->data[0].aidata;
recend = (const char *) found->data + found->recsize;
/* Now check if we can trust ai_resp fields. If GC is
in progress, it can contain anything. */
if (mapped->head->gc_cycle != gc_cycle)
{
retval = -2;
goto out;
}
}
}
/* If we do not have the cache mapped, try to get the data over the
socket. */
if (respdata == NULL)
{
sock = __nscd_open_socket (key, keylen, GETAI, &ai_resp,
sizeof (ai_resp));
if (sock == -1)
{
/* nscd not running or wrong version. */
__nss_not_use_nscd_hosts = 1;
goto out;
}
}
if (ai_resp.found == 1)
{
size_t datalen = ai_resp.naddrs + ai_resp.addrslen + ai_resp.canonlen;
/* This check really only affects the case where the data
comes from the mapped cache. */
if (respdata + datalen > recend)
{
assert (sock == -1);
goto out;
}
/* Create result. */
resultbuf = (struct nscd_ai_result *) malloc (sizeof (*resultbuf)
+ datalen);
if (resultbuf == NULL)
{
*h_errnop = NETDB_INTERNAL;
goto out_close;
}
/* Set up the data structure, including pointers. */
resultbuf->naddrs = ai_resp.naddrs;
resultbuf->addrs = (char *) (resultbuf + 1);
resultbuf->family = (uint8_t *) (resultbuf->addrs + ai_resp.addrslen);
if (ai_resp.canonlen != 0)
resultbuf->canon = (char *) (resultbuf->family + resultbuf->naddrs);
else
resultbuf->canon = NULL;
if (respdata == NULL)
{
/* Read the data from the socket. */
if ((size_t) __readall (sock, resultbuf + 1, datalen) == datalen)
{
retval = 0;
*result = resultbuf;
}
else
{
free (resultbuf);
*h_errnop = NETDB_INTERNAL;
}
}
else
{
/* Copy the data in the block. */
memcpy (resultbuf + 1, respdata, datalen);
/* Try to detect corrupt databases. */
if (resultbuf->canon != NULL
&& resultbuf->canon[ai_resp.canonlen - 1] != '\0')
/* We cannot use the database. */
{
if (mapped->head->gc_cycle != gc_cycle)
retval = -2;
else
free (resultbuf);
goto out_close;
}
retval = 0;
*result = resultbuf;
}
}
else
{
if (__glibc_unlikely (ai_resp.found == -1))
{
/* The daemon does not cache this database. */
__nss_not_use_nscd_hosts = 1;
goto out_close;
}
/* Store the error number. */
*h_errnop = ai_resp.error;
/* Set errno to 0 to indicate no error, just no found record. */
__set_errno (0);
/* Even though we have not found anything, the result is zero. */
retval = 0;
}
out_close:
if (sock != -1)
close_not_cancel_no_status (sock);
out:
if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
{
/* When we come here this means there has been a GC cycle while we
were looking for the data. This means the data might have been
inconsistent. Retry if possible. */
if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
{
/* nscd is just running gc now. Disable using the mapping. */
if (atomic_decrement_val (&mapped->counter) == 0)
__nscd_unmap (mapped);
mapped = NO_MAPPING;
}
if (retval != -1)
{
*result = NULL;
free (resultbuf);
goto retry;
}
}
return retval;
}
|
GitWeb