[457] | 1 | /*
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| 2 | * magic.c - PPP Magic Number routines.
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| 3 | *
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| 4 | * Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
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| 5 | *
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| 6 | * Redistribution and use in source and binary forms, with or without
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| 7 | * modification, are permitted provided that the following conditions
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| 8 | * are met:
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| 9 | *
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| 10 | * 1. Redistributions of source code must retain the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer.
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| 12 | *
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| 13 | * 2. Redistributions in binary form must reproduce the above copyright
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| 14 | * notice, this list of conditions and the following disclaimer in
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| 15 | * the documentation and/or other materials provided with the
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| 16 | * distribution.
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| 17 | *
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| 18 | * 3. The name "Carnegie Mellon University" must not be used to
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| 19 | * endorse or promote products derived from this software without
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| 20 | * prior written permission. For permission or any legal
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| 21 | * details, please contact
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| 22 | * Office of Technology Transfer
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| 23 | * Carnegie Mellon University
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| 24 | * 5000 Forbes Avenue
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| 25 | * Pittsburgh, PA 15213-3890
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| 26 | * (412) 268-4387, fax: (412) 268-7395
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| 27 | * tech-transfer@andrew.cmu.edu
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| 28 | *
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| 29 | * 4. Redistributions of any form whatsoever must retain the following
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| 30 | * acknowledgment:
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| 31 | * "This product includes software developed by Computing Services
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| 32 | * at Carnegie Mellon University (http://www.cmu.edu/computing/)."
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| 33 | *
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| 34 | * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
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| 35 | * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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| 36 | * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
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| 37 | * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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| 38 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
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| 39 | * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
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| 40 | * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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| 41 | */
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| 42 | /*****************************************************************************
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| 43 | * randm.c - Random number generator program file.
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| 44 | *
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| 45 | * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
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| 46 | * Copyright (c) 1998 by Global Election Systems Inc.
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| 47 | *
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| 48 | * The authors hereby grant permission to use, copy, modify, distribute,
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| 49 | * and license this software and its documentation for any purpose, provided
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| 50 | * that existing copyright notices are retained in all copies and that this
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| 51 | * notice and the following disclaimer are included verbatim in any
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| 52 | * distributions. No written agreement, license, or royalty fee is required
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| 53 | * for any of the authorized uses.
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| 54 | *
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| 55 | * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
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| 56 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 57 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 58 | * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 59 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 60 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 61 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 62 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 63 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 64 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 65 | *
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| 66 | ******************************************************************************
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| 67 | * REVISION HISTORY
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| 68 | *
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| 69 | * 03-01-01 Marc Boucher <marc@mbsi.ca>
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| 70 | * Ported to lwIP.
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| 71 | * 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
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| 72 | * Extracted from avos.
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| 73 | *****************************************************************************/
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| 74 |
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| 75 | #include "netif/ppp/ppp_opts.h"
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| 76 | #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
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| 77 |
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| 78 | #include "netif/ppp/ppp_impl.h"
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| 79 | #include "netif/ppp/magic.h"
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| 80 |
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| 81 | #if PPP_MD5_RANDM /* Using MD5 for better randomness if enabled */
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| 82 |
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| 83 | #include "netif/ppp/pppcrypt.h"
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| 84 |
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| 85 | #define MD5_HASH_SIZE 16
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| 86 | static char magic_randpool[MD5_HASH_SIZE]; /* Pool of randomness. */
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| 87 | static long magic_randcount; /* Pseudo-random incrementer */
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| 88 | static u32_t magic_randomseed; /* Seed used for random number generation. */
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| 89 |
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| 90 | /*
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| 91 | * Churn the randomness pool on a random event. Call this early and often
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| 92 | * on random and semi-random system events to build randomness in time for
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| 93 | * usage. For randomly timed events, pass a null pointer and a zero length
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| 94 | * and this will use the system timer and other sources to add randomness.
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| 95 | * If new random data is available, pass a pointer to that and it will be
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| 96 | * included.
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| 97 | *
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| 98 | * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
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| 99 | */
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| 100 | static void magic_churnrand(char *rand_data, u32_t rand_len) {
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| 101 | lwip_md5_context md5_ctx;
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| 102 |
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| 103 | /* LWIP_DEBUGF(LOG_INFO, ("magic_churnrand: %u@%P\n", rand_len, rand_data)); */
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| 104 | lwip_md5_init(&md5_ctx);
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| 105 | lwip_md5_starts(&md5_ctx);
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| 106 | lwip_md5_update(&md5_ctx, (u_char *)magic_randpool, sizeof(magic_randpool));
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| 107 | if (rand_data) {
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| 108 | lwip_md5_update(&md5_ctx, (u_char *)rand_data, rand_len);
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| 109 | } else {
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| 110 | struct {
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| 111 | /* INCLUDE fields for any system sources of randomness */
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| 112 | u32_t jiffies;
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| 113 | #ifdef LWIP_RAND
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| 114 | u32_t rand;
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| 115 | #endif /* LWIP_RAND */
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| 116 | } sys_data;
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| 117 | magic_randomseed += sys_jiffies();
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| 118 | sys_data.jiffies = magic_randomseed;
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| 119 | #ifdef LWIP_RAND
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| 120 | sys_data.rand = LWIP_RAND();
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| 121 | #endif /* LWIP_RAND */
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| 122 | /* Load sys_data fields here. */
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| 123 | lwip_md5_update(&md5_ctx, (u_char *)&sys_data, sizeof(sys_data));
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| 124 | }
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| 125 | lwip_md5_finish(&md5_ctx, (u_char *)magic_randpool);
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| 126 | lwip_md5_free(&md5_ctx);
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| 127 | /* LWIP_DEBUGF(LOG_INFO, ("magic_churnrand: -> 0\n")); */
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| 128 | }
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| 129 |
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| 130 | /*
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| 131 | * Initialize the random number generator.
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| 132 | */
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| 133 | void magic_init(void) {
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| 134 | magic_churnrand(NULL, 0);
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| 135 | }
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| 136 |
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| 137 | /*
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| 138 | * Randomize our random seed value.
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| 139 | */
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| 140 | void magic_randomize(void) {
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| 141 | magic_churnrand(NULL, 0);
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| 142 | }
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| 143 |
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| 144 | /*
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| 145 | * magic_random_bytes - Fill a buffer with random bytes.
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| 146 | *
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| 147 | * Use the random pool to generate random data. This degrades to pseudo
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| 148 | * random when used faster than randomness is supplied using magic_churnrand().
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| 149 | * Note: It's important that there be sufficient randomness in magic_randpool
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| 150 | * before this is called for otherwise the range of the result may be
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| 151 | * narrow enough to make a search feasible.
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| 152 | *
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| 153 | * Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
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| 154 | *
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| 155 | * XXX Why does he not just call magic_churnrand() for each block? Probably
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| 156 | * so that you don't ever publish the seed which could possibly help
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| 157 | * predict future values.
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| 158 | * XXX Why don't we preserve md5 between blocks and just update it with
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| 159 | * magic_randcount each time? Probably there is a weakness but I wish that
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| 160 | * it was documented.
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| 161 | */
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| 162 | void magic_random_bytes(unsigned char *buf, u32_t buf_len) {
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| 163 | lwip_md5_context md5_ctx;
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| 164 | u_char tmp[MD5_HASH_SIZE];
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| 165 | u32_t n;
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| 166 |
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| 167 | while (buf_len > 0) {
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| 168 | lwip_md5_init(&md5_ctx);
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| 169 | lwip_md5_starts(&md5_ctx);
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| 170 | lwip_md5_update(&md5_ctx, (u_char *)magic_randpool, sizeof(magic_randpool));
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| 171 | lwip_md5_update(&md5_ctx, (u_char *)&magic_randcount, sizeof(magic_randcount));
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| 172 | lwip_md5_finish(&md5_ctx, tmp);
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| 173 | lwip_md5_free(&md5_ctx);
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| 174 | magic_randcount++;
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| 175 | n = LWIP_MIN(buf_len, MD5_HASH_SIZE);
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| 176 | MEMCPY(buf, tmp, n);
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| 177 | buf += n;
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| 178 | buf_len -= n;
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| 179 | }
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| 180 | }
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| 181 |
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| 182 | /*
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| 183 | * Return a new random number.
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| 184 | */
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| 185 | u32_t magic(void) {
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| 186 | u32_t new_rand;
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| 187 |
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| 188 | magic_random_bytes((unsigned char *)&new_rand, sizeof(new_rand));
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| 189 |
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| 190 | return new_rand;
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| 191 | }
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| 192 |
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| 193 | #else /* PPP_MD5_RANDM */
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| 194 |
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| 195 | /*****************************/
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| 196 | /*** LOCAL DATA STRUCTURES ***/
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| 197 | /*****************************/
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| 198 | #ifndef LWIP_RAND
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| 199 | static int magic_randomized; /* Set when truely randomized. */
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| 200 | #endif /* LWIP_RAND */
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| 201 | static u32_t magic_randomseed; /* Seed used for random number generation. */
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| 202 |
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| 203 |
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| 204 | /***********************************/
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| 205 | /*** PUBLIC FUNCTION DEFINITIONS ***/
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| 206 | /***********************************/
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| 207 |
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| 208 | /*
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| 209 | * Initialize the random number generator.
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| 210 | *
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| 211 | * Here we attempt to compute a random number seed but even if
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| 212 | * it isn't random, we'll randomize it later.
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| 213 | *
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| 214 | * The current method uses the fields from the real time clock,
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| 215 | * the idle process counter, the millisecond counter, and the
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| 216 | * hardware timer tick counter. When this is invoked
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| 217 | * in startup(), then the idle counter and timer values may
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| 218 | * repeat after each boot and the real time clock may not be
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| 219 | * operational. Thus we call it again on the first random
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| 220 | * event.
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| 221 | */
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| 222 | void magic_init(void) {
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| 223 | magic_randomseed += sys_jiffies();
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| 224 | #ifndef LWIP_RAND
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| 225 | /* Initialize the Borland random number generator. */
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| 226 | srand((unsigned)magic_randomseed);
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| 227 | #endif /* LWIP_RAND */
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| 228 | }
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| 229 |
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| 230 | /*
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| 231 | * magic_init - Initialize the magic number generator.
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| 232 | *
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| 233 | * Randomize our random seed value. Here we use the fact that
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| 234 | * this function is called at *truely random* times by the polling
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| 235 | * and network functions. Here we only get 16 bits of new random
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| 236 | * value but we use the previous value to randomize the other 16
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| 237 | * bits.
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| 238 | */
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| 239 | void magic_randomize(void) {
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| 240 | #ifndef LWIP_RAND
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| 241 | if (!magic_randomized) {
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| 242 | magic_randomized = !0;
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| 243 | magic_init();
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| 244 | /* The initialization function also updates the seed. */
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| 245 | } else {
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| 246 | #endif /* LWIP_RAND */
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| 247 | magic_randomseed += sys_jiffies();
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| 248 | #ifndef LWIP_RAND
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| 249 | }
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| 250 | #endif /* LWIP_RAND */
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| 251 | }
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| 252 |
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| 253 | /*
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| 254 | * Return a new random number.
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| 255 | *
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| 256 | * Here we use the Borland rand() function to supply a pseudo random
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| 257 | * number which we make truely random by combining it with our own
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| 258 | * seed which is randomized by truely random events.
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| 259 | * Thus the numbers will be truely random unless there have been no
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| 260 | * operator or network events in which case it will be pseudo random
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| 261 | * seeded by the real time clock.
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| 262 | */
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| 263 | u32_t magic(void) {
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| 264 | #ifdef LWIP_RAND
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| 265 | return LWIP_RAND() + magic_randomseed;
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| 266 | #else /* LWIP_RAND */
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| 267 | return ((u32_t)rand() << 16) + (u32_t)rand() + magic_randomseed;
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| 268 | #endif /* LWIP_RAND */
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| 269 | }
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| 270 |
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| 271 | /*
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| 272 | * magic_random_bytes - Fill a buffer with random bytes.
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| 273 | */
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| 274 | void magic_random_bytes(unsigned char *buf, u32_t buf_len) {
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| 275 | u32_t new_rand, n;
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| 276 |
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| 277 | while (buf_len > 0) {
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| 278 | new_rand = magic();
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| 279 | n = LWIP_MIN(buf_len, sizeof(new_rand));
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| 280 | MEMCPY(buf, &new_rand, n);
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| 281 | buf += n;
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| 282 | buf_len -= n;
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| 283 | }
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| 284 | }
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| 285 | #endif /* PPP_MD5_RANDM */
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| 286 |
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| 287 | /*
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| 288 | * Return a new random number between 0 and (2^pow)-1 included.
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| 289 | */
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| 290 | u32_t magic_pow(u8_t pow) {
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| 291 | return magic() & ~(~0UL<<pow);
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| 292 | }
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| 293 |
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| 294 | #endif /* PPP_SUPPORT */
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