annotate dbrandom.c @ 1200:9a944a243f08 DROPBEAR_2015.71

2015.71
author Matt Johnston <matt@ucc.asn.au>
date Thu, 03 Dec 2015 21:23:54 +0800
parents a9e4d66ffb2c
children 9da3e7b4fe55
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1 /*
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2 * Dropbear - a SSH2 server
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3 *
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4 * Copyright (c) 2002,2003 Matt Johnston
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5 * All rights reserved.
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6 *
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7 * Permission is hereby granted, free of charge, to any person obtaining a copy
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8 * of this software and associated documentation files (the "Software"), to deal
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9 * in the Software without restriction, including without limitation the rights
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10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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11 * copies of the Software, and to permit persons to whom the Software is
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12 * furnished to do so, subject to the following conditions:
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13 *
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14 * The above copyright notice and this permission notice shall be included in
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15 * all copies or substantial portions of the Software.
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16 *
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17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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23 * SOFTWARE. */
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24
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25 #include "includes.h"
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26 #include "buffer.h"
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27 #include "dbutil.h"
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28 #include "bignum.h"
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29 #include "dbrandom.h"
4
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30
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31
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32 /* this is used to generate unique output from the same hashpool */
272
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33 static uint32_t counter = 0;
298
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34 /* the max value for the counter, so it won't integer overflow */
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35 #define MAX_COUNTER 1<<30
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36
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37 static unsigned char hashpool[SHA1_HASH_SIZE] = {0};
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38 static int donerandinit = 0;
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39
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40 #define INIT_SEED_SIZE 32 /* 256 bits */
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41
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42 /* The basic setup is we read some data from /dev/(u)random or prngd and hash it
4
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43 * into hashpool. To read data, we hash together current hashpool contents,
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44 * and a counter. We feed more data in by hashing the current pool and new
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45 * data into the pool.
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46 *
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47 * It is important to ensure that counter doesn't wrap around before we
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48 * feed in new entropy.
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49 *
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50 */
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51
687
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52 /* Pass len=0 to hash an entire file */
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53 static int
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54 process_file(hash_state *hs, const char *filename,
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55 unsigned int len, int prngd)
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56 {
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57 static int already_blocked = 0;
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58 int readfd;
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59 unsigned int readcount;
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60 int ret = DROPBEAR_FAILURE;
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61
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62 #ifdef DROPBEAR_PRNGD_SOCKET
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63 if (prngd)
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64 {
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65 readfd = connect_unix(filename);
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66 }
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67 else
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68 #endif
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69 {
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70 readfd = open(filename, O_RDONLY);
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71 }
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72
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73 if (readfd < 0) {
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74 goto out;
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75 }
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76
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77 readcount = 0;
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78 while (len == 0 || readcount < len)
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79 {
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80 int readlen, wantread;
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81 unsigned char readbuf[4096];
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82 if (!already_blocked && !prngd)
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83 {
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84 int res;
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85 struct timeval timeout;
185
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86 fd_set read_fds;
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87
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88 timeout.tv_sec = 2;
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89 timeout.tv_usec = 0;
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90
185
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91 FD_ZERO(&read_fds);
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92 FD_SET(readfd, &read_fds);
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93 res = select(readfd + 1, &read_fds, NULL, NULL, &timeout);
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94 if (res == 0)
185
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95 {
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96 dropbear_log(LOG_WARNING, "Warning: Reading the randomness source '%s' seems to have blocked.\nYou may need to find a better entropy source.", filename);
185
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97 already_blocked = 1;
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98 }
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99 }
687
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100
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101 if (len == 0)
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102 {
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103 wantread = sizeof(readbuf);
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104 }
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105 else
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106 {
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107 wantread = MIN(sizeof(readbuf), len-readcount);
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108 }
687
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109
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110 #ifdef DROPBEAR_PRNGD_SOCKET
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111 if (prngd)
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112 {
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113 char egdcmd[2];
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114 egdcmd[0] = 0x02; /* blocking read */
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115 egdcmd[1] = (unsigned char)wantread;
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116 if (write(readfd, egdcmd, 2) < 0)
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117 {
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118 dropbear_exit("Can't send command to egd");
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119 }
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120 }
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121 #endif
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122
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123 readlen = read(readfd, readbuf, wantread);
4
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124 if (readlen <= 0) {
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125 if (readlen < 0 && errno == EINTR) {
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126 continue;
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127 }
687
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128 if (readlen == 0 && len == 0)
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129 {
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130 /* whole file was read as requested */
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131 break;
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132 }
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133 goto out;
4
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134 }
687
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135 sha1_process(hs, readbuf, readlen);
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136 readcount += readlen;
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137 }
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138 ret = DROPBEAR_SUCCESS;
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139 out:
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140 close(readfd);
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141 return ret;
4
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142 }
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143
1096
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Gaël PORTAY <gael.portay@gmail.com>
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144 void addrandom(unsigned char * buf, unsigned int len)
687
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145 {
4
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146 hash_state hs;
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147
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148 /* hash in the new seed data */
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149 sha1_init(&hs);
687
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150 /* existing state (zeroes on startup) */
4
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151 sha1_process(&hs, (void*)hashpool, sizeof(hashpool));
687
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152
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153 /* new */
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parents: 602
diff changeset
154 sha1_process(&hs, buf, len);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
155 sha1_done(&hs, hashpool);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
156 }
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
157
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
158 static void write_urandom()
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
159 {
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
160 #ifndef DROPBEAR_PRNGD_SOCKET
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
161 /* This is opportunistic, don't worry about failure */
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
162 unsigned char buf[INIT_SEED_SIZE];
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
163 FILE *f = fopen(DROPBEAR_URANDOM_DEV, "w");
737
7deb6fda1319 fix tabs
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parents: 735
diff changeset
164 if (!f) {
7deb6fda1319 fix tabs
Matt Johnston <matt@ucc.asn.au>
parents: 735
diff changeset
165 return;
7deb6fda1319 fix tabs
Matt Johnston <matt@ucc.asn.au>
parents: 735
diff changeset
166 }
687
167fdc091c05 Improve RNG seeding.
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diff changeset
167 genrandom(buf, sizeof(buf));
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
168 fwrite(buf, sizeof(buf), 1, f);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
169 fclose(f);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
170 #endif
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
171 }
167fdc091c05 Improve RNG seeding.
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diff changeset
172
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parents: 602
diff changeset
173 /* Initialise the prng from /dev/urandom or prngd. This function can
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
174 * be called multiple times */
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
175 void seedrandom() {
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
176
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diff changeset
177 hash_state hs;
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
178
167fdc091c05 Improve RNG seeding.
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diff changeset
179 pid_t pid;
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
180 struct timeval tv;
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
181 clock_t clockval;
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
182
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
183 /* hash in the new seed data */
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
184 sha1_init(&hs);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
185 /* existing state */
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
186 sha1_process(&hs, (void*)hashpool, sizeof(hashpool));
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parents: 602
diff changeset
187
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
188 #ifdef DROPBEAR_PRNGD_SOCKET
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diff changeset
189 if (process_file(&hs, DROPBEAR_PRNGD_SOCKET, INIT_SEED_SIZE, 1)
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
190 != DROPBEAR_SUCCESS) {
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
191 dropbear_exit("Failure reading random device %s",
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
192 DROPBEAR_PRNGD_SOCKET);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
193 }
167fdc091c05 Improve RNG seeding.
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diff changeset
194 #else
167fdc091c05 Improve RNG seeding.
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diff changeset
195 /* non-blocking random source (probably /dev/urandom) */
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
196 if (process_file(&hs, DROPBEAR_URANDOM_DEV, INIT_SEED_SIZE, 0)
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
197 != DROPBEAR_SUCCESS) {
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
198 dropbear_exit("Failure reading random device %s",
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
199 DROPBEAR_URANDOM_DEV);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
200 }
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
201 #endif
167fdc091c05 Improve RNG seeding.
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diff changeset
202
694
c85bb68e1db6 add loadavg and entropy_avail as sources
Matt Johnston <matt@ucc.asn.au>
parents: 689
diff changeset
203 /* A few other sources to fall back on.
c85bb68e1db6 add loadavg and entropy_avail as sources
Matt Johnston <matt@ucc.asn.au>
parents: 689
diff changeset
204 * Add more here for other platforms */
687
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
205 #ifdef __linux__
688
650c41a4909a Add a few more files in /proc for Linux
Matt Johnston <matt@ucc.asn.au>
parents: 687
diff changeset
206 /* Seems to be a reasonable source of entropy from timers. Possibly hard
650c41a4909a Add a few more files in /proc for Linux
Matt Johnston <matt@ucc.asn.au>
parents: 687
diff changeset
207 * for even local attackers to reproduce */
687
167fdc091c05 Improve RNG seeding.
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diff changeset
208 process_file(&hs, "/proc/timer_list", 0, 0);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
209 /* Might help on systems with wireless */
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
210 process_file(&hs, "/proc/interrupts", 0, 0);
688
650c41a4909a Add a few more files in /proc for Linux
Matt Johnston <matt@ucc.asn.au>
parents: 687
diff changeset
211
694
c85bb68e1db6 add loadavg and entropy_avail as sources
Matt Johnston <matt@ucc.asn.au>
parents: 689
diff changeset
212 process_file(&hs, "/proc/loadavg", 0, 0);
c85bb68e1db6 add loadavg and entropy_avail as sources
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parents: 689
diff changeset
213 process_file(&hs, "/proc/sys/kernel/random/entropy_avail", 0, 0);
c85bb68e1db6 add loadavg and entropy_avail as sources
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parents: 689
diff changeset
214
811
5de524aec047 limit how much we read from rt_cache etc
Matt Johnston <matt@ucc.asn.au>
parents: 737
diff changeset
215 /* Mostly network visible but useful in some situations.
5de524aec047 limit how much we read from rt_cache etc
Matt Johnston <matt@ucc.asn.au>
parents: 737
diff changeset
216 * Limit size to avoid slowdowns on systems with lots of routes */
5de524aec047 limit how much we read from rt_cache etc
Matt Johnston <matt@ucc.asn.au>
parents: 737
diff changeset
217 process_file(&hs, "/proc/net/netstat", 4096, 0);
5de524aec047 limit how much we read from rt_cache etc
Matt Johnston <matt@ucc.asn.au>
parents: 737
diff changeset
218 process_file(&hs, "/proc/net/dev", 4096, 0);
5de524aec047 limit how much we read from rt_cache etc
Matt Johnston <matt@ucc.asn.au>
parents: 737
diff changeset
219 process_file(&hs, "/proc/net/tcp", 4096, 0);
688
650c41a4909a Add a few more files in /proc for Linux
Matt Johnston <matt@ucc.asn.au>
parents: 687
diff changeset
220 /* Also includes interface lo */
811
5de524aec047 limit how much we read from rt_cache etc
Matt Johnston <matt@ucc.asn.au>
parents: 737
diff changeset
221 process_file(&hs, "/proc/net/rt_cache", 4096, 0);
702
48e173a0c52b Include /proc/vmstat as another random source
Matt Johnston <matt@ucc.asn.au>
parents: 698
diff changeset
222 process_file(&hs, "/proc/vmstat", 0, 0);
687
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
223 #endif
167fdc091c05 Improve RNG seeding.
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diff changeset
224
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
225 pid = getpid();
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
226 sha1_process(&hs, (void*)&pid, sizeof(pid));
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
227
857
c19acba28590 use oldstyle comments
Matt Johnston <matt@ucc.asn.au>
parents: 855
diff changeset
228 /* gettimeofday() doesn't completely fill out struct timeval on
c19acba28590 use oldstyle comments
Matt Johnston <matt@ucc.asn.au>
parents: 855
diff changeset
229 OS X (10.8.3), avoid valgrind warnings by clearing it first */
714
84157e435c52 Make sure "struct timeval" is initialised on OS X to avoid valgrind warnings
Matt Johnston <matt@ucc.asn.au>
parents: 702
diff changeset
230 memset(&tv, 0x0, sizeof(tv));
687
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
231 gettimeofday(&tv, NULL);
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
232 sha1_process(&hs, (void*)&tv, sizeof(tv));
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
233
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
234 clockval = clock();
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
235 sha1_process(&hs, (void*)&clockval, sizeof(clockval));
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
236
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
237 /* When a private key is read by the client or server it will
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
238 * be added to the hashpool - see runopts.c */
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
239
4
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
240 sha1_done(&hs, hashpool);
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
241
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
242 counter = 0;
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
243 donerandinit = 1;
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
244
687
167fdc091c05 Improve RNG seeding.
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parents: 602
diff changeset
245 /* Feed it all back into /dev/urandom - this might help if Dropbear
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
246 * is running from inetd and gets new state each time */
167fdc091c05 Improve RNG seeding.
Matt Johnston <matt@ucc.asn.au>
parents: 602
diff changeset
247 write_urandom();
272
3be7ae2e8dfa Only read /dev/random once when the program starts
Matt Johnston <matt@ucc.asn.au>
parents: 198
diff changeset
248 }
3be7ae2e8dfa Only read /dev/random once when the program starts
Matt Johnston <matt@ucc.asn.au>
parents: 198
diff changeset
249
4
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
250 /* return len bytes of pseudo-random data */
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
251 void genrandom(unsigned char* buf, unsigned int len) {
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
252
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
253 hash_state hs;
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
254 unsigned char hash[SHA1_HASH_SIZE];
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
255 unsigned int copylen;
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
256
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
257 if (!donerandinit) {
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
258 dropbear_exit("seedrandom not done");
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
259 }
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
260
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
261 while (len > 0) {
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
262 sha1_init(&hs);
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
263 sha1_process(&hs, (void*)hashpool, sizeof(hashpool));
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
264 sha1_process(&hs, (void*)&counter, sizeof(counter));
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
265 sha1_done(&hs, hash);
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
266
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
267 counter++;
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
268 if (counter > MAX_COUNTER) {
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
269 seedrandom();
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
270 }
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
271
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
272 copylen = MIN(len, SHA1_HASH_SIZE);
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
273 memcpy(buf, hash, copylen);
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
274 len -= copylen;
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
275 buf += copylen;
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
276 }
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
277 m_burn(hash, sizeof(hash));
fe6bca95afa7 Makefile.in contains updated files required
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
278 }
188
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
279
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
280 /* Generates a random mp_int.
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
281 * max is a *mp_int specifying an upper bound.
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
282 * rand must be an initialised *mp_int for the result.
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
283 * the result rand satisfies: 0 < rand < max
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
284 * */
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
285 void gen_random_mpint(mp_int *max, mp_int *rand) {
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
286
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
287 unsigned char *randbuf = NULL;
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
288 unsigned int len = 0;
433
c216212001fc Fix for -pedantic -ansi compilation, change // to /**/, plus some signedness
Matt Johnston <matt@ucc.asn.au>
parents: 405
diff changeset
289 const unsigned char masks[] = {0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f};
188
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
290
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
291 const int size_bits = mp_count_bits(max);
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
292
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
293 len = size_bits / 8;
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
294 if ((size_bits % 8) != 0) {
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
295 len += 1;
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
296 }
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
297
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
298 randbuf = (unsigned char*)m_malloc(len);
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
299 do {
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
300 genrandom(randbuf, len);
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
301 /* Mask out the unrequired bits - mp_read_unsigned_bin expects
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
302 * MSB first.*/
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
303 randbuf[0] &= masks[size_bits % 8];
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
304
c9483550701b - refactored random mp_int generation and byte->mp_int code
Matt Johnston <matt@ucc.asn.au>
parents: 159
diff changeset
305 bytes_to_mp(rand, randbuf, len);
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306
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307 /* keep regenerating until we get one satisfying
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308 * 0 < rand < max */
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a1e79ffa5862 Tighten validation of DH values. Odds of x==0 being generated are
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309 } while (!(mp_cmp(rand, max) == MP_LT && mp_cmp_d(rand, 0) == MP_GT));
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310 m_burn(randbuf, len);
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311 m_free(randbuf);
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312 }