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10a89ef0 1/* Copyright (c) 2008, 2009, 2010, 2011, 2013 Nicira, Inc.
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2 *
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16#include <config.h>
17
18#include "entropy.h"
19
20#include <errno.h>
21#include <fcntl.h>
22#include <unistd.h>
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23#ifdef _WIN32
24#include <Wincrypt.h>
25#endif
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26
27#include "socket-util.h"
28#include "vlog.h"
29
d98e6007 30VLOG_DEFINE_THIS_MODULE(entropy);
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31
32static const char urandom[] = "/dev/urandom";
33
34/* Initializes 'buffer' with 'n' bytes of high-quality random numbers. Returns
35 * 0 if successful, otherwise a positive errno value or EOF on error. */
36int
37get_entropy(void *buffer, size_t n)
38{
5d386c06 39#ifndef _WIN32
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40 size_t bytes_read;
41 int error;
42 int fd;
43
44 fd = open(urandom, O_RDONLY);
45 if (fd < 0) {
10a89ef0 46 VLOG_ERR("%s: open failed (%s)", urandom, ovs_strerror(errno));
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47 return errno ? errno : EINVAL;
48 }
49
50 error = read_fully(fd, buffer, n, &bytes_read);
51 close(fd);
52
53 if (error) {
fe1e967e 54 VLOG_ERR("%s: read error (%s)", urandom, ovs_retval_to_string(error));
e251c8d0 55 }
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56#else
57 int error = 0;
58 HCRYPTPROV crypt_prov = 0;
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59
60 CryptAcquireContext(&crypt_prov, NULL, NULL,
61 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
62 if (!CryptGenRandom(crypt_prov, n, buffer)) {
06f14c92 63 char *msg_buf = ovs_lasterror_to_string();
5d386c06 64 error = EINVAL;
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65 VLOG_ERR("CryptGenRandom: read error (%s)", msg_buf);
66 LocalFree(msg_buf);
67 }
68
69 CryptReleaseContext(crypt_prov, 0);
70#endif
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71 return error;
72}
73
74/* Initializes 'buffer' with 'n' bytes of high-quality random numbers. Exits
75 * if an error occurs. */
76void
77get_entropy_or_die(void *buffer, size_t n)
78{
79 int error = get_entropy(buffer, n);
80 if (error) {
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81 VLOG_FATAL("%s: read error (%s)",
82 urandom, ovs_retval_to_string(error));
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83 }
84}