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Darran Shepherd / Mbed 2 deprecated Bonjour

First step: AutoIP compiled in and working

lwip/netif/ppp/randm.c@1:4218cacaf696, 2010-06-18 (annotated)

Committer:: darran
Date:: Fri Jun 18 15:54:21 2010 +0000
Revision:: 1:4218cacaf696
Parent:: 0:55a05330f8cc

Who changed what in which revision?

User	Revision	Line number	New contents of line
darran	0:55a05330f8cc	1	/*****************************************************************************
darran	0:55a05330f8cc	2	* randm.c - Random number generator program file.
darran	0:55a05330f8cc	3	*
darran	0:55a05330f8cc	4	* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
darran	0:55a05330f8cc	5	* Copyright (c) 1998 by Global Election Systems Inc.
darran	0:55a05330f8cc	6	*
darran	0:55a05330f8cc	7	* The authors hereby grant permission to use, copy, modify, distribute,
darran	0:55a05330f8cc	8	* and license this software and its documentation for any purpose, provided
darran	0:55a05330f8cc	9	* that existing copyright notices are retained in all copies and that this
darran	0:55a05330f8cc	10	* notice and the following disclaimer are included verbatim in any
darran	0:55a05330f8cc	11	* distributions. No written agreement, license, or royalty fee is required
darran	0:55a05330f8cc	12	* for any of the authorized uses.
darran	0:55a05330f8cc	13	*
darran	0:55a05330f8cc	14	* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS AS IS AND ANY EXPRESS OR
darran	0:55a05330f8cc	15	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
darran	0:55a05330f8cc	16	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
darran	0:55a05330f8cc	17	* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
darran	0:55a05330f8cc	18	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
darran	0:55a05330f8cc	19	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
darran	0:55a05330f8cc	20	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
darran	0:55a05330f8cc	21	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
darran	0:55a05330f8cc	22	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
darran	0:55a05330f8cc	23	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
darran	0:55a05330f8cc	24	*
darran	0:55a05330f8cc	25	******************************************************************************
darran	0:55a05330f8cc	26	* REVISION HISTORY
darran	0:55a05330f8cc	27	*
darran	0:55a05330f8cc	28	* 03-01-01 Marc Boucher <marc@mbsi.ca>
darran	0:55a05330f8cc	29	* Ported to lwIP.
darran	0:55a05330f8cc	30	* 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
darran	0:55a05330f8cc	31	* Extracted from avos.
darran	0:55a05330f8cc	32	*****************************************************************************/
darran	0:55a05330f8cc	33
darran	0:55a05330f8cc	34	#include "lwip/opt.h"
darran	0:55a05330f8cc	35
darran	0:55a05330f8cc	36	#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
darran	0:55a05330f8cc	37
darran	0:55a05330f8cc	38	#include "md5.h"
darran	0:55a05330f8cc	39	#include "randm.h"
darran	0:55a05330f8cc	40
darran	0:55a05330f8cc	41	#include "ppp.h"
darran	0:55a05330f8cc	42	#include "pppdebug.h"
darran	0:55a05330f8cc	43
darran	0:55a05330f8cc	44	#include <string.h>
darran	0:55a05330f8cc	45
darran	0:55a05330f8cc	46	#if MD5_SUPPORT /* this module depends on MD5 */
darran	0:55a05330f8cc	47	#define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
darran	0:55a05330f8cc	48
darran	0:55a05330f8cc	49	/*****************************/
darran	0:55a05330f8cc	50	/* LOCAL DATA STRUCTURES */
darran	0:55a05330f8cc	51	/*****************************/
darran	0:55a05330f8cc	52	static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
darran	0:55a05330f8cc	53	static long randCount = 0; /* Pseudo-random incrementer */
darran	0:55a05330f8cc	54
darran	0:55a05330f8cc	55
darran	0:55a05330f8cc	56	/***********************************/
darran	0:55a05330f8cc	57	/* PUBLIC FUNCTION DEFINITIONS */
darran	0:55a05330f8cc	58	/***********************************/
darran	0:55a05330f8cc	59	/*
darran	0:55a05330f8cc	60	* Initialize the random number generator.
darran	0:55a05330f8cc	61	*
darran	0:55a05330f8cc	62	* Since this is to be called on power up, we don't have much
darran	0:55a05330f8cc	63	* system randomess to work with. Here all we use is the
darran	0:55a05330f8cc	64	* real-time clock. We'll accumulate more randomness as soon
darran	0:55a05330f8cc	65	* as things start happening.
darran	0:55a05330f8cc	66	*/
darran	0:55a05330f8cc	67	void
darran	0:55a05330f8cc	68	avRandomInit()
darran	0:55a05330f8cc	69	{
darran	0:55a05330f8cc	70	avChurnRand(NULL, 0);
darran	0:55a05330f8cc	71	}
darran	0:55a05330f8cc	72
darran	0:55a05330f8cc	73	/*
darran	0:55a05330f8cc	74	* Churn the randomness pool on a random event. Call this early and often
darran	0:55a05330f8cc	75	* on random and semi-random system events to build randomness in time for
darran	0:55a05330f8cc	76	* usage. For randomly timed events, pass a null pointer and a zero length
darran	0:55a05330f8cc	77	* and this will use the system timer and other sources to add randomness.
darran	0:55a05330f8cc	78	* If new random data is available, pass a pointer to that and it will be
darran	0:55a05330f8cc	79	* included.
darran	0:55a05330f8cc	80	*
darran	0:55a05330f8cc	81	* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
darran	0:55a05330f8cc	82	*/
darran	0:55a05330f8cc	83	void
darran	0:55a05330f8cc	84	avChurnRand(char *randData, u32_t randLen)
darran	0:55a05330f8cc	85	{
darran	0:55a05330f8cc	86	MD5_CTX md5;
darran	0:55a05330f8cc	87
darran	0:55a05330f8cc	88	/* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
darran	0:55a05330f8cc	89	MD5Init(&md5);
darran	0:55a05330f8cc	90	MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
darran	0:55a05330f8cc	91	if (randData) {
darran	0:55a05330f8cc	92	MD5Update(&md5, (u_char *)randData, randLen);
darran	0:55a05330f8cc	93	} else {
darran	0:55a05330f8cc	94	struct {
darran	0:55a05330f8cc	95	/* INCLUDE fields for any system sources of randomness */
darran	0:55a05330f8cc	96	char foobar;
darran	0:55a05330f8cc	97	} sysData;
darran	0:55a05330f8cc	98
darran	0:55a05330f8cc	99	/* Load sysData fields here. */
darran	0:55a05330f8cc	100	MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
darran	0:55a05330f8cc	101	}
darran	0:55a05330f8cc	102	MD5Final((u_char *)randPool, &md5);
darran	0:55a05330f8cc	103	/* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
darran	0:55a05330f8cc	104	}
darran	0:55a05330f8cc	105
darran	0:55a05330f8cc	106	/*
darran	0:55a05330f8cc	107	* Use the random pool to generate random data. This degrades to pseudo
darran	0:55a05330f8cc	108	* random when used faster than randomness is supplied using churnRand().
darran	0:55a05330f8cc	109	* Note: It's important that there be sufficient randomness in randPool
darran	0:55a05330f8cc	110	* before this is called for otherwise the range of the result may be
darran	0:55a05330f8cc	111	* narrow enough to make a search feasible.
darran	0:55a05330f8cc	112	*
darran	0:55a05330f8cc	113	* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
darran	0:55a05330f8cc	114	*
darran	0:55a05330f8cc	115	* XXX Why does he not just call churnRand() for each block? Probably
darran	0:55a05330f8cc	116	* so that you don't ever publish the seed which could possibly help
darran	0:55a05330f8cc	117	* predict future values.
darran	0:55a05330f8cc	118	* XXX Why don't we preserve md5 between blocks and just update it with
darran	0:55a05330f8cc	119	* randCount each time? Probably there is a weakness but I wish that
darran	0:55a05330f8cc	120	* it was documented.
darran	0:55a05330f8cc	121	*/
darran	0:55a05330f8cc	122	void
darran	0:55a05330f8cc	123	avGenRand(char *buf, u32_t bufLen)
darran	0:55a05330f8cc	124	{
darran	0:55a05330f8cc	125	MD5_CTX md5;
darran	0:55a05330f8cc	126	u_char tmp[16];
darran	0:55a05330f8cc	127	u32_t n;
darran	0:55a05330f8cc	128
darran	0:55a05330f8cc	129	while (bufLen > 0) {
darran	0:55a05330f8cc	130	n = LWIP_MIN(bufLen, RANDPOOLSZ);
darran	0:55a05330f8cc	131	MD5Init(&md5);
darran	0:55a05330f8cc	132	MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
darran	0:55a05330f8cc	133	MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
darran	0:55a05330f8cc	134	MD5Final(tmp, &md5);
darran	0:55a05330f8cc	135	randCount++;
darran	0:55a05330f8cc	136	MEMCPY(buf, tmp, n);
darran	0:55a05330f8cc	137	buf += n;
darran	0:55a05330f8cc	138	bufLen -= n;
darran	0:55a05330f8cc	139	}
darran	0:55a05330f8cc	140	}
darran	0:55a05330f8cc	141
darran	0:55a05330f8cc	142	/*
darran	0:55a05330f8cc	143	* Return a new random number.
darran	0:55a05330f8cc	144	*/
darran	0:55a05330f8cc	145	u32_t
darran	0:55a05330f8cc	146	avRandom()
darran	0:55a05330f8cc	147	{
darran	0:55a05330f8cc	148	u32_t newRand;
darran	0:55a05330f8cc	149
darran	0:55a05330f8cc	150	avGenRand((char *)&newRand, sizeof(newRand));
darran	0:55a05330f8cc	151
darran	0:55a05330f8cc	152	return newRand;
darran	0:55a05330f8cc	153	}
darran	0:55a05330f8cc	154
darran	0:55a05330f8cc	155	#else /* MD5_SUPPORT */
darran	0:55a05330f8cc	156
darran	0:55a05330f8cc	157	/*****************************/
darran	0:55a05330f8cc	158	/* LOCAL DATA STRUCTURES */
darran	0:55a05330f8cc	159	/*****************************/
darran	0:55a05330f8cc	160	static int avRandomized = 0; /* Set when truely randomized. */
darran	0:55a05330f8cc	161	static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
darran	0:55a05330f8cc	162
darran	0:55a05330f8cc	163
darran	0:55a05330f8cc	164	/***********************************/
darran	0:55a05330f8cc	165	/* PUBLIC FUNCTION DEFINITIONS */
darran	0:55a05330f8cc	166	/***********************************/
darran	0:55a05330f8cc	167	/*
darran	0:55a05330f8cc	168	* Initialize the random number generator.
darran	0:55a05330f8cc	169	*
darran	0:55a05330f8cc	170	* Here we attempt to compute a random number seed but even if
darran	0:55a05330f8cc	171	* it isn't random, we'll randomize it later.
darran	0:55a05330f8cc	172	*
darran	0:55a05330f8cc	173	* The current method uses the fields from the real time clock,
darran	0:55a05330f8cc	174	* the idle process counter, the millisecond counter, and the
darran	0:55a05330f8cc	175	* hardware timer tick counter. When this is invoked
darran	0:55a05330f8cc	176	* in startup(), then the idle counter and timer values may
darran	0:55a05330f8cc	177	* repeat after each boot and the real time clock may not be
darran	0:55a05330f8cc	178	* operational. Thus we call it again on the first random
darran	0:55a05330f8cc	179	* event.
darran	0:55a05330f8cc	180	*/
darran	0:55a05330f8cc	181	void
darran	0:55a05330f8cc	182	avRandomInit()
darran	0:55a05330f8cc	183	{
darran	0:55a05330f8cc	184	#if 0
darran	0:55a05330f8cc	185	/* Get a pointer into the last 4 bytes of clockBuf. */
darran	0:55a05330f8cc	186	u32_t lptr1 = (u32_t )((char *)&clockBuf[3]);
darran	0:55a05330f8cc	187
darran	0:55a05330f8cc	188	/*
darran	0:55a05330f8cc	189	* Initialize our seed using the real-time clock, the idle
darran	0:55a05330f8cc	190	* counter, the millisecond timer, and the hardware timer
darran	0:55a05330f8cc	191	* tick counter. The real-time clock and the hardware
darran	0:55a05330f8cc	192	* tick counter are the best sources of randomness but
darran	0:55a05330f8cc	193	* since the tick counter is only 16 bit (and truncated
darran	0:55a05330f8cc	194	* at that), the idle counter and millisecond timer
darran	0:55a05330f8cc	195	* (which may be small values) are added to help
darran	0:55a05330f8cc	196	* randomize the lower 16 bits of the seed.
darran	0:55a05330f8cc	197	*/
darran	0:55a05330f8cc	198	readClk();
darran	0:55a05330f8cc	199	avRandomSeed += (u32_t )clockBuf + *lptr1 + OSIdleCtr
darran	0:55a05330f8cc	200	+ ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
darran	0:55a05330f8cc	201	#else
darran	0:55a05330f8cc	202	avRandomSeed += sys_jiffies(); /* XXX */
darran	0:55a05330f8cc	203	#endif
darran	0:55a05330f8cc	204
darran	0:55a05330f8cc	205	/* Initialize the Borland random number generator. */
darran	0:55a05330f8cc	206	srand((unsigned)avRandomSeed);
darran	0:55a05330f8cc	207	}
darran	0:55a05330f8cc	208
darran	0:55a05330f8cc	209	/*
darran	0:55a05330f8cc	210	* Randomize our random seed value. Here we use the fact that
darran	0:55a05330f8cc	211	* this function is called at truely random times by the polling
darran	0:55a05330f8cc	212	* and network functions. Here we only get 16 bits of new random
darran	0:55a05330f8cc	213	* value but we use the previous value to randomize the other 16
darran	0:55a05330f8cc	214	* bits.
darran	0:55a05330f8cc	215	*/
darran	0:55a05330f8cc	216	void
darran	0:55a05330f8cc	217	avRandomize(void)
darran	0:55a05330f8cc	218	{
darran	0:55a05330f8cc	219	static u32_t last_jiffies;
darran	0:55a05330f8cc	220
darran	0:55a05330f8cc	221	if (!avRandomized) {
darran	0:55a05330f8cc	222	avRandomized = !0;
darran	0:55a05330f8cc	223	avRandomInit();
darran	0:55a05330f8cc	224	/* The initialization function also updates the seed. */
darran	0:55a05330f8cc	225	} else {
darran	0:55a05330f8cc	226	/* avRandomSeed += (avRandomSeed << 16) + TM1; */
darran	0:55a05330f8cc	227	avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
darran	0:55a05330f8cc	228	}
darran	0:55a05330f8cc	229	last_jiffies = sys_jiffies();
darran	0:55a05330f8cc	230	}
darran	0:55a05330f8cc	231
darran	0:55a05330f8cc	232	/*
darran	0:55a05330f8cc	233	* Return a new random number.
darran	0:55a05330f8cc	234	* Here we use the Borland rand() function to supply a pseudo random
darran	0:55a05330f8cc	235	* number which we make truely random by combining it with our own
darran	0:55a05330f8cc	236	* seed which is randomized by truely random events.
darran	0:55a05330f8cc	237	* Thus the numbers will be truely random unless there have been no
darran	0:55a05330f8cc	238	* operator or network events in which case it will be pseudo random
darran	0:55a05330f8cc	239	* seeded by the real time clock.
darran	0:55a05330f8cc	240	*/
darran	0:55a05330f8cc	241	u32_t
darran	0:55a05330f8cc	242	avRandom()
darran	0:55a05330f8cc	243	{
darran	0:55a05330f8cc	244	return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
darran	0:55a05330f8cc	245	}
darran	0:55a05330f8cc	246
darran	0:55a05330f8cc	247	#endif /* MD5_SUPPORT */
darran	0:55a05330f8cc	248
darran	0:55a05330f8cc	249	#endif /* PPP_SUPPORT */

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	18 Jun 2010
Imports:	7
Forks:	0
Commits:	2
Dependents:	0
Dependencies:	1
Followers:	1

lwip/netif/ppp/randm.c@1:4218cacaf696, 2010-06-18 (annotated)

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