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1 /* Copyright (c) 2008, 2009, 2010, 2011, 2013 Nicira, Inc.
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>
23 #ifdef _WIN32
24 #include <Wincrypt.h>
25 #endif
26 #include "util.h"
27 #include "socket-util.h"
28 #include "openvswitch/vlog.h"
29
30 VLOG_DEFINE_THIS_MODULE(entropy);
31
32 static 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. */
36 int
37 get_entropy(void *buffer, size_t n)
38 {
39 #ifndef _WIN32
40 size_t bytes_read;
41 int error;
42 int fd;
43
44 fd = open(urandom, O_RDONLY);
45 if (fd < 0) {
46 VLOG_ERR("%s: open failed (%s)", urandom, ovs_strerror(errno));
47 return errno ? errno : EINVAL;
48 }
49
50 error = read_fully(fd, buffer, n, &bytes_read);
51 close(fd);
52
53 if (error) {
54 VLOG_ERR("%s: read error (%s)", urandom, ovs_retval_to_string(error));
55 }
56 #else
57 int error = 0;
58 HCRYPTPROV crypt_prov = 0;
59
60 CryptAcquireContext(&crypt_prov, NULL, NULL,
61 PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
62 if (!CryptGenRandom(crypt_prov, n, buffer)) {
63 VLOG_ERR("CryptGenRandom: read error (%s)", ovs_lasterror_to_string());
64 error = EINVAL;
65 }
66
67 CryptReleaseContext(crypt_prov, 0);
68 #endif
69 return error;
70 }
71
72 /* Initializes 'buffer' with 'n' bytes of high-quality random numbers. Exits
73 * if an error occurs. */
74 void
75 get_entropy_or_die(void *buffer, size_t n)
76 {
77 int error = get_entropy(buffer, n);
78 if (error) {
79 VLOG_FATAL("%s: read error (%s)",
80 urandom, ovs_retval_to_string(error));
81 }
82 }