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This library is stripped down version of NetServices library. HTTP server and client function is NOT supported.

lwip/netif/ppp/randm.c@0:dcf3c92487ca, 2011-07-20 (annotated)

Committer:: idinor
Date:: Wed Jul 20 11:45:39 2011 +0000
Revision:: 0:dcf3c92487ca

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User	Revision	Line number	New contents of line
idinor	0:dcf3c92487ca	1	/*****************************************************************************
idinor	0:dcf3c92487ca	2	* randm.c - Random number generator program file.
idinor	0:dcf3c92487ca	3	*
idinor	0:dcf3c92487ca	4	* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
idinor	0:dcf3c92487ca	5	* Copyright (c) 1998 by Global Election Systems Inc.
idinor	0:dcf3c92487ca	6	*
idinor	0:dcf3c92487ca	7	* The authors hereby grant permission to use, copy, modify, distribute,
idinor	0:dcf3c92487ca	8	* and license this software and its documentation for any purpose, provided
idinor	0:dcf3c92487ca	9	* that existing copyright notices are retained in all copies and that this
idinor	0:dcf3c92487ca	10	* notice and the following disclaimer are included verbatim in any
idinor	0:dcf3c92487ca	11	* distributions. No written agreement, license, or royalty fee is required
idinor	0:dcf3c92487ca	12	* for any of the authorized uses.
idinor	0:dcf3c92487ca	13	*
idinor	0:dcf3c92487ca	14	* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS AS IS AND ANY EXPRESS OR
idinor	0:dcf3c92487ca	15	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
idinor	0:dcf3c92487ca	16	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
idinor	0:dcf3c92487ca	17	* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
idinor	0:dcf3c92487ca	18	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
idinor	0:dcf3c92487ca	19	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
idinor	0:dcf3c92487ca	20	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
idinor	0:dcf3c92487ca	21	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
idinor	0:dcf3c92487ca	22	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
idinor	0:dcf3c92487ca	23	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
idinor	0:dcf3c92487ca	24	*
idinor	0:dcf3c92487ca	25	******************************************************************************
idinor	0:dcf3c92487ca	26	* REVISION HISTORY
idinor	0:dcf3c92487ca	27	*
idinor	0:dcf3c92487ca	28	* 03-01-01 Marc Boucher <marc@mbsi.ca>
idinor	0:dcf3c92487ca	29	* Ported to lwIP.
idinor	0:dcf3c92487ca	30	* 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
idinor	0:dcf3c92487ca	31	* Extracted from avos.
idinor	0:dcf3c92487ca	32	*****************************************************************************/
idinor	0:dcf3c92487ca	33
idinor	0:dcf3c92487ca	34	#include "lwip/opt.h"
idinor	0:dcf3c92487ca	35
idinor	0:dcf3c92487ca	36	#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
idinor	0:dcf3c92487ca	37
idinor	0:dcf3c92487ca	38	#include "md5.h"
idinor	0:dcf3c92487ca	39	#include "randm.h"
idinor	0:dcf3c92487ca	40
idinor	0:dcf3c92487ca	41	#include "ppp.h"
idinor	0:dcf3c92487ca	42	#include "pppdebug.h"
idinor	0:dcf3c92487ca	43
idinor	0:dcf3c92487ca	44	#include <string.h>
idinor	0:dcf3c92487ca	45
idinor	0:dcf3c92487ca	46	#if MD5_SUPPORT /* this module depends on MD5 */
idinor	0:dcf3c92487ca	47	#define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
idinor	0:dcf3c92487ca	48
idinor	0:dcf3c92487ca	49	/*****************************/
idinor	0:dcf3c92487ca	50	/* LOCAL DATA STRUCTURES */
idinor	0:dcf3c92487ca	51	/*****************************/
idinor	0:dcf3c92487ca	52	static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
idinor	0:dcf3c92487ca	53	static long randCount = 0; /* Pseudo-random incrementer */
idinor	0:dcf3c92487ca	54
idinor	0:dcf3c92487ca	55
idinor	0:dcf3c92487ca	56	/***********************************/
idinor	0:dcf3c92487ca	57	/* PUBLIC FUNCTION DEFINITIONS */
idinor	0:dcf3c92487ca	58	/***********************************/
idinor	0:dcf3c92487ca	59	/*
idinor	0:dcf3c92487ca	60	* Initialize the random number generator.
idinor	0:dcf3c92487ca	61	*
idinor	0:dcf3c92487ca	62	* Since this is to be called on power up, we don't have much
idinor	0:dcf3c92487ca	63	* system randomess to work with. Here all we use is the
idinor	0:dcf3c92487ca	64	* real-time clock. We'll accumulate more randomness as soon
idinor	0:dcf3c92487ca	65	* as things start happening.
idinor	0:dcf3c92487ca	66	*/
idinor	0:dcf3c92487ca	67	void
idinor	0:dcf3c92487ca	68	avRandomInit()
idinor	0:dcf3c92487ca	69	{
idinor	0:dcf3c92487ca	70	avChurnRand(NULL, 0);
idinor	0:dcf3c92487ca	71	}
idinor	0:dcf3c92487ca	72
idinor	0:dcf3c92487ca	73	/*
idinor	0:dcf3c92487ca	74	* Churn the randomness pool on a random event. Call this early and often
idinor	0:dcf3c92487ca	75	* on random and semi-random system events to build randomness in time for
idinor	0:dcf3c92487ca	76	* usage. For randomly timed events, pass a null pointer and a zero length
idinor	0:dcf3c92487ca	77	* and this will use the system timer and other sources to add randomness.
idinor	0:dcf3c92487ca	78	* If new random data is available, pass a pointer to that and it will be
idinor	0:dcf3c92487ca	79	* included.
idinor	0:dcf3c92487ca	80	*
idinor	0:dcf3c92487ca	81	* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
idinor	0:dcf3c92487ca	82	*/
idinor	0:dcf3c92487ca	83	void
idinor	0:dcf3c92487ca	84	avChurnRand(char *randData, u32_t randLen)
idinor	0:dcf3c92487ca	85	{
idinor	0:dcf3c92487ca	86	MD5_CTX md5;
idinor	0:dcf3c92487ca	87
idinor	0:dcf3c92487ca	88	/* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
idinor	0:dcf3c92487ca	89	MD5Init(&md5);
idinor	0:dcf3c92487ca	90	MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
idinor	0:dcf3c92487ca	91	if (randData) {
idinor	0:dcf3c92487ca	92	MD5Update(&md5, (u_char *)randData, randLen);
idinor	0:dcf3c92487ca	93	} else {
idinor	0:dcf3c92487ca	94	struct {
idinor	0:dcf3c92487ca	95	/* INCLUDE fields for any system sources of randomness */
idinor	0:dcf3c92487ca	96	char foobar;
idinor	0:dcf3c92487ca	97	} sysData;
idinor	0:dcf3c92487ca	98
idinor	0:dcf3c92487ca	99	/* Load sysData fields here. */
idinor	0:dcf3c92487ca	100	MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
idinor	0:dcf3c92487ca	101	}
idinor	0:dcf3c92487ca	102	MD5Final((u_char *)randPool, &md5);
idinor	0:dcf3c92487ca	103	/* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
idinor	0:dcf3c92487ca	104	}
idinor	0:dcf3c92487ca	105
idinor	0:dcf3c92487ca	106	/*
idinor	0:dcf3c92487ca	107	* Use the random pool to generate random data. This degrades to pseudo
idinor	0:dcf3c92487ca	108	* random when used faster than randomness is supplied using churnRand().
idinor	0:dcf3c92487ca	109	* Note: It's important that there be sufficient randomness in randPool
idinor	0:dcf3c92487ca	110	* before this is called for otherwise the range of the result may be
idinor	0:dcf3c92487ca	111	* narrow enough to make a search feasible.
idinor	0:dcf3c92487ca	112	*
idinor	0:dcf3c92487ca	113	* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
idinor	0:dcf3c92487ca	114	*
idinor	0:dcf3c92487ca	115	* XXX Why does he not just call churnRand() for each block? Probably
idinor	0:dcf3c92487ca	116	* so that you don't ever publish the seed which could possibly help
idinor	0:dcf3c92487ca	117	* predict future values.
idinor	0:dcf3c92487ca	118	* XXX Why don't we preserve md5 between blocks and just update it with
idinor	0:dcf3c92487ca	119	* randCount each time? Probably there is a weakness but I wish that
idinor	0:dcf3c92487ca	120	* it was documented.
idinor	0:dcf3c92487ca	121	*/
idinor	0:dcf3c92487ca	122	void
idinor	0:dcf3c92487ca	123	avGenRand(char *buf, u32_t bufLen)
idinor	0:dcf3c92487ca	124	{
idinor	0:dcf3c92487ca	125	MD5_CTX md5;
idinor	0:dcf3c92487ca	126	u_char tmp[16];
idinor	0:dcf3c92487ca	127	u32_t n;
idinor	0:dcf3c92487ca	128
idinor	0:dcf3c92487ca	129	while (bufLen > 0) {
idinor	0:dcf3c92487ca	130	n = LWIP_MIN(bufLen, RANDPOOLSZ);
idinor	0:dcf3c92487ca	131	MD5Init(&md5);
idinor	0:dcf3c92487ca	132	MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
idinor	0:dcf3c92487ca	133	MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
idinor	0:dcf3c92487ca	134	MD5Final(tmp, &md5);
idinor	0:dcf3c92487ca	135	randCount++;
idinor	0:dcf3c92487ca	136	MEMCPY(buf, tmp, n);
idinor	0:dcf3c92487ca	137	buf += n;
idinor	0:dcf3c92487ca	138	bufLen -= n;
idinor	0:dcf3c92487ca	139	}
idinor	0:dcf3c92487ca	140	}
idinor	0:dcf3c92487ca	141
idinor	0:dcf3c92487ca	142	/*
idinor	0:dcf3c92487ca	143	* Return a new random number.
idinor	0:dcf3c92487ca	144	*/
idinor	0:dcf3c92487ca	145	u32_t
idinor	0:dcf3c92487ca	146	avRandom()
idinor	0:dcf3c92487ca	147	{
idinor	0:dcf3c92487ca	148	u32_t newRand;
idinor	0:dcf3c92487ca	149
idinor	0:dcf3c92487ca	150	avGenRand((char *)&newRand, sizeof(newRand));
idinor	0:dcf3c92487ca	151
idinor	0:dcf3c92487ca	152	return newRand;
idinor	0:dcf3c92487ca	153	}
idinor	0:dcf3c92487ca	154
idinor	0:dcf3c92487ca	155	#else /* MD5_SUPPORT */
idinor	0:dcf3c92487ca	156
idinor	0:dcf3c92487ca	157	/*****************************/
idinor	0:dcf3c92487ca	158	/* LOCAL DATA STRUCTURES */
idinor	0:dcf3c92487ca	159	/*****************************/
idinor	0:dcf3c92487ca	160	static int avRandomized = 0; /* Set when truely randomized. */
idinor	0:dcf3c92487ca	161	static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
idinor	0:dcf3c92487ca	162
idinor	0:dcf3c92487ca	163
idinor	0:dcf3c92487ca	164	/***********************************/
idinor	0:dcf3c92487ca	165	/* PUBLIC FUNCTION DEFINITIONS */
idinor	0:dcf3c92487ca	166	/***********************************/
idinor	0:dcf3c92487ca	167	/*
idinor	0:dcf3c92487ca	168	* Initialize the random number generator.
idinor	0:dcf3c92487ca	169	*
idinor	0:dcf3c92487ca	170	* Here we attempt to compute a random number seed but even if
idinor	0:dcf3c92487ca	171	* it isn't random, we'll randomize it later.
idinor	0:dcf3c92487ca	172	*
idinor	0:dcf3c92487ca	173	* The current method uses the fields from the real time clock,
idinor	0:dcf3c92487ca	174	* the idle process counter, the millisecond counter, and the
idinor	0:dcf3c92487ca	175	* hardware timer tick counter. When this is invoked
idinor	0:dcf3c92487ca	176	* in startup(), then the idle counter and timer values may
idinor	0:dcf3c92487ca	177	* repeat after each boot and the real time clock may not be
idinor	0:dcf3c92487ca	178	* operational. Thus we call it again on the first random
idinor	0:dcf3c92487ca	179	* event.
idinor	0:dcf3c92487ca	180	*/
idinor	0:dcf3c92487ca	181	void
idinor	0:dcf3c92487ca	182	avRandomInit()
idinor	0:dcf3c92487ca	183	{
idinor	0:dcf3c92487ca	184	#if 0
idinor	0:dcf3c92487ca	185	/* Get a pointer into the last 4 bytes of clockBuf. */
idinor	0:dcf3c92487ca	186	u32_t lptr1 = (u32_t )((char *)&clockBuf[3]);
idinor	0:dcf3c92487ca	187
idinor	0:dcf3c92487ca	188	/*
idinor	0:dcf3c92487ca	189	* Initialize our seed using the real-time clock, the idle
idinor	0:dcf3c92487ca	190	* counter, the millisecond timer, and the hardware timer
idinor	0:dcf3c92487ca	191	* tick counter. The real-time clock and the hardware
idinor	0:dcf3c92487ca	192	* tick counter are the best sources of randomness but
idinor	0:dcf3c92487ca	193	* since the tick counter is only 16 bit (and truncated
idinor	0:dcf3c92487ca	194	* at that), the idle counter and millisecond timer
idinor	0:dcf3c92487ca	195	* (which may be small values) are added to help
idinor	0:dcf3c92487ca	196	* randomize the lower 16 bits of the seed.
idinor	0:dcf3c92487ca	197	*/
idinor	0:dcf3c92487ca	198	readClk();
idinor	0:dcf3c92487ca	199	avRandomSeed += (u32_t )clockBuf + *lptr1 + OSIdleCtr
idinor	0:dcf3c92487ca	200	+ ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
idinor	0:dcf3c92487ca	201	#else
idinor	0:dcf3c92487ca	202	avRandomSeed += sys_jiffies(); /* XXX */
idinor	0:dcf3c92487ca	203	#endif
idinor	0:dcf3c92487ca	204
idinor	0:dcf3c92487ca	205	/* Initialize the Borland random number generator. */
idinor	0:dcf3c92487ca	206	srand((unsigned)avRandomSeed);
idinor	0:dcf3c92487ca	207	}
idinor	0:dcf3c92487ca	208
idinor	0:dcf3c92487ca	209	/*
idinor	0:dcf3c92487ca	210	* Randomize our random seed value. Here we use the fact that
idinor	0:dcf3c92487ca	211	* this function is called at truely random times by the polling
idinor	0:dcf3c92487ca	212	* and network functions. Here we only get 16 bits of new random
idinor	0:dcf3c92487ca	213	* value but we use the previous value to randomize the other 16
idinor	0:dcf3c92487ca	214	* bits.
idinor	0:dcf3c92487ca	215	*/
idinor	0:dcf3c92487ca	216	void
idinor	0:dcf3c92487ca	217	avRandomize(void)
idinor	0:dcf3c92487ca	218	{
idinor	0:dcf3c92487ca	219	static u32_t last_jiffies;
idinor	0:dcf3c92487ca	220
idinor	0:dcf3c92487ca	221	if (!avRandomized) {
idinor	0:dcf3c92487ca	222	avRandomized = !0;
idinor	0:dcf3c92487ca	223	avRandomInit();
idinor	0:dcf3c92487ca	224	/* The initialization function also updates the seed. */
idinor	0:dcf3c92487ca	225	} else {
idinor	0:dcf3c92487ca	226	/* avRandomSeed += (avRandomSeed << 16) + TM1; */
idinor	0:dcf3c92487ca	227	avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
idinor	0:dcf3c92487ca	228	}
idinor	0:dcf3c92487ca	229	last_jiffies = sys_jiffies();
idinor	0:dcf3c92487ca	230	}
idinor	0:dcf3c92487ca	231
idinor	0:dcf3c92487ca	232	/*
idinor	0:dcf3c92487ca	233	* Return a new random number.
idinor	0:dcf3c92487ca	234	* Here we use the Borland rand() function to supply a pseudo random
idinor	0:dcf3c92487ca	235	* number which we make truely random by combining it with our own
idinor	0:dcf3c92487ca	236	* seed which is randomized by truely random events.
idinor	0:dcf3c92487ca	237	* Thus the numbers will be truely random unless there have been no
idinor	0:dcf3c92487ca	238	* operator or network events in which case it will be pseudo random
idinor	0:dcf3c92487ca	239	* seeded by the real time clock.
idinor	0:dcf3c92487ca	240	*/
idinor	0:dcf3c92487ca	241	u32_t
idinor	0:dcf3c92487ca	242	avRandom()
idinor	0:dcf3c92487ca	243	{
idinor	0:dcf3c92487ca	244	return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
idinor	0:dcf3c92487ca	245	}
idinor	0:dcf3c92487ca	246
idinor	0:dcf3c92487ca	247	#endif /* MD5_SUPPORT */
idinor	0:dcf3c92487ca	248
idinor	0:dcf3c92487ca	249	#endif /* PPP_SUPPORT */

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Type:	Library
Created:	20 Jul 2011
Imports:	35
Forks:	0
Commits:	1
Dependents:	1
Dependencies:	0
Followers:	1

lwip/netif/ppp/randm.c@0:dcf3c92487ca, 2011-07-20 (annotated)

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