AmpereMeter - Example self-announcing webserver which controls …

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Dirk-Willem van Gulik (NXP/mbed) / Mbed 2 deprecated AmpereMeter

Example self-announcing webserver which controls a servo through a smallHTML userinterface.

lwip/netif/ppp/randm.c@0:a259777c45a3, 2010-08-14 (annotated)

Committer:: dirkx
Date:: Sat Aug 14 15:56:01 2010 +0000
Revision:: 0:a259777c45a3

Who changed what in which revision?

User	Revision	Line number	New contents of line
dirkx	0:a259777c45a3	1	/*****************************************************************************
dirkx	0:a259777c45a3	2	* randm.c - Random number generator program file.
dirkx	0:a259777c45a3	3	*
dirkx	0:a259777c45a3	4	* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
dirkx	0:a259777c45a3	5	* Copyright (c) 1998 by Global Election Systems Inc.
dirkx	0:a259777c45a3	6	*
dirkx	0:a259777c45a3	7	* The authors hereby grant permission to use, copy, modify, distribute,
dirkx	0:a259777c45a3	8	* and license this software and its documentation for any purpose, provided
dirkx	0:a259777c45a3	9	* that existing copyright notices are retained in all copies and that this
dirkx	0:a259777c45a3	10	* notice and the following disclaimer are included verbatim in any
dirkx	0:a259777c45a3	11	* distributions. No written agreement, license, or royalty fee is required
dirkx	0:a259777c45a3	12	* for any of the authorized uses.
dirkx	0:a259777c45a3	13	*
dirkx	0:a259777c45a3	14	* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS AS IS AND ANY EXPRESS OR
dirkx	0:a259777c45a3	15	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
dirkx	0:a259777c45a3	16	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
dirkx	0:a259777c45a3	17	* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
dirkx	0:a259777c45a3	18	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
dirkx	0:a259777c45a3	19	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
dirkx	0:a259777c45a3	20	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
dirkx	0:a259777c45a3	21	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
dirkx	0:a259777c45a3	22	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
dirkx	0:a259777c45a3	23	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
dirkx	0:a259777c45a3	24	*
dirkx	0:a259777c45a3	25	******************************************************************************
dirkx	0:a259777c45a3	26	* REVISION HISTORY
dirkx	0:a259777c45a3	27	*
dirkx	0:a259777c45a3	28	* 03-01-01 Marc Boucher <marc@mbsi.ca>
dirkx	0:a259777c45a3	29	* Ported to lwIP.
dirkx	0:a259777c45a3	30	* 98-06-03 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
dirkx	0:a259777c45a3	31	* Extracted from avos.
dirkx	0:a259777c45a3	32	*****************************************************************************/
dirkx	0:a259777c45a3	33
dirkx	0:a259777c45a3	34	#include "lwip/opt.h"
dirkx	0:a259777c45a3	35
dirkx	0:a259777c45a3	36	#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
dirkx	0:a259777c45a3	37
dirkx	0:a259777c45a3	38	#include "md5.h"
dirkx	0:a259777c45a3	39	#include "randm.h"
dirkx	0:a259777c45a3	40
dirkx	0:a259777c45a3	41	#include "ppp.h"
dirkx	0:a259777c45a3	42	#include "pppdebug.h"
dirkx	0:a259777c45a3	43
dirkx	0:a259777c45a3	44	#include <string.h>
dirkx	0:a259777c45a3	45
dirkx	0:a259777c45a3	46	#if MD5_SUPPORT /* this module depends on MD5 */
dirkx	0:a259777c45a3	47	#define RANDPOOLSZ 16 /* Bytes stored in the pool of randomness. */
dirkx	0:a259777c45a3	48
dirkx	0:a259777c45a3	49	/*****************************/
dirkx	0:a259777c45a3	50	/* LOCAL DATA STRUCTURES */
dirkx	0:a259777c45a3	51	/*****************************/
dirkx	0:a259777c45a3	52	static char randPool[RANDPOOLSZ]; /* Pool of randomness. */
dirkx	0:a259777c45a3	53	static long randCount = 0; /* Pseudo-random incrementer */
dirkx	0:a259777c45a3	54
dirkx	0:a259777c45a3	55
dirkx	0:a259777c45a3	56	/***********************************/
dirkx	0:a259777c45a3	57	/* PUBLIC FUNCTION DEFINITIONS */
dirkx	0:a259777c45a3	58	/***********************************/
dirkx	0:a259777c45a3	59	/*
dirkx	0:a259777c45a3	60	* Initialize the random number generator.
dirkx	0:a259777c45a3	61	*
dirkx	0:a259777c45a3	62	* Since this is to be called on power up, we don't have much
dirkx	0:a259777c45a3	63	* system randomess to work with. Here all we use is the
dirkx	0:a259777c45a3	64	* real-time clock. We'll accumulate more randomness as soon
dirkx	0:a259777c45a3	65	* as things start happening.
dirkx	0:a259777c45a3	66	*/
dirkx	0:a259777c45a3	67	void
dirkx	0:a259777c45a3	68	avRandomInit()
dirkx	0:a259777c45a3	69	{
dirkx	0:a259777c45a3	70	avChurnRand(NULL, 0);
dirkx	0:a259777c45a3	71	}
dirkx	0:a259777c45a3	72
dirkx	0:a259777c45a3	73	/*
dirkx	0:a259777c45a3	74	* Churn the randomness pool on a random event. Call this early and often
dirkx	0:a259777c45a3	75	* on random and semi-random system events to build randomness in time for
dirkx	0:a259777c45a3	76	* usage. For randomly timed events, pass a null pointer and a zero length
dirkx	0:a259777c45a3	77	* and this will use the system timer and other sources to add randomness.
dirkx	0:a259777c45a3	78	* If new random data is available, pass a pointer to that and it will be
dirkx	0:a259777c45a3	79	* included.
dirkx	0:a259777c45a3	80	*
dirkx	0:a259777c45a3	81	* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
dirkx	0:a259777c45a3	82	*/
dirkx	0:a259777c45a3	83	void
dirkx	0:a259777c45a3	84	avChurnRand(char *randData, u32_t randLen)
dirkx	0:a259777c45a3	85	{
dirkx	0:a259777c45a3	86	MD5_CTX md5;
dirkx	0:a259777c45a3	87
dirkx	0:a259777c45a3	88	/* LWIP_DEBUGF(LOG_INFO, ("churnRand: %u@%P\n", randLen, randData)); */
dirkx	0:a259777c45a3	89	MD5Init(&md5);
dirkx	0:a259777c45a3	90	MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
dirkx	0:a259777c45a3	91	if (randData) {
dirkx	0:a259777c45a3	92	MD5Update(&md5, (u_char *)randData, randLen);
dirkx	0:a259777c45a3	93	} else {
dirkx	0:a259777c45a3	94	struct {
dirkx	0:a259777c45a3	95	/* INCLUDE fields for any system sources of randomness */
dirkx	0:a259777c45a3	96	char foobar;
dirkx	0:a259777c45a3	97	} sysData;
dirkx	0:a259777c45a3	98
dirkx	0:a259777c45a3	99	/* Load sysData fields here. */
dirkx	0:a259777c45a3	100	MD5Update(&md5, (u_char *)&sysData, sizeof(sysData));
dirkx	0:a259777c45a3	101	}
dirkx	0:a259777c45a3	102	MD5Final((u_char *)randPool, &md5);
dirkx	0:a259777c45a3	103	/* LWIP_DEBUGF(LOG_INFO, ("churnRand: -> 0\n")); */
dirkx	0:a259777c45a3	104	}
dirkx	0:a259777c45a3	105
dirkx	0:a259777c45a3	106	/*
dirkx	0:a259777c45a3	107	* Use the random pool to generate random data. This degrades to pseudo
dirkx	0:a259777c45a3	108	* random when used faster than randomness is supplied using churnRand().
dirkx	0:a259777c45a3	109	* Note: It's important that there be sufficient randomness in randPool
dirkx	0:a259777c45a3	110	* before this is called for otherwise the range of the result may be
dirkx	0:a259777c45a3	111	* narrow enough to make a search feasible.
dirkx	0:a259777c45a3	112	*
dirkx	0:a259777c45a3	113	* Ref: Applied Cryptography 2nd Ed. by Bruce Schneier p. 427
dirkx	0:a259777c45a3	114	*
dirkx	0:a259777c45a3	115	* XXX Why does he not just call churnRand() for each block? Probably
dirkx	0:a259777c45a3	116	* so that you don't ever publish the seed which could possibly help
dirkx	0:a259777c45a3	117	* predict future values.
dirkx	0:a259777c45a3	118	* XXX Why don't we preserve md5 between blocks and just update it with
dirkx	0:a259777c45a3	119	* randCount each time? Probably there is a weakness but I wish that
dirkx	0:a259777c45a3	120	* it was documented.
dirkx	0:a259777c45a3	121	*/
dirkx	0:a259777c45a3	122	void
dirkx	0:a259777c45a3	123	avGenRand(char *buf, u32_t bufLen)
dirkx	0:a259777c45a3	124	{
dirkx	0:a259777c45a3	125	MD5_CTX md5;
dirkx	0:a259777c45a3	126	u_char tmp[16];
dirkx	0:a259777c45a3	127	u32_t n;
dirkx	0:a259777c45a3	128
dirkx	0:a259777c45a3	129	while (bufLen > 0) {
dirkx	0:a259777c45a3	130	n = LWIP_MIN(bufLen, RANDPOOLSZ);
dirkx	0:a259777c45a3	131	MD5Init(&md5);
dirkx	0:a259777c45a3	132	MD5Update(&md5, (u_char *)randPool, sizeof(randPool));
dirkx	0:a259777c45a3	133	MD5Update(&md5, (u_char *)&randCount, sizeof(randCount));
dirkx	0:a259777c45a3	134	MD5Final(tmp, &md5);
dirkx	0:a259777c45a3	135	randCount++;
dirkx	0:a259777c45a3	136	MEMCPY(buf, tmp, n);
dirkx	0:a259777c45a3	137	buf += n;
dirkx	0:a259777c45a3	138	bufLen -= n;
dirkx	0:a259777c45a3	139	}
dirkx	0:a259777c45a3	140	}
dirkx	0:a259777c45a3	141
dirkx	0:a259777c45a3	142	/*
dirkx	0:a259777c45a3	143	* Return a new random number.
dirkx	0:a259777c45a3	144	*/
dirkx	0:a259777c45a3	145	u32_t
dirkx	0:a259777c45a3	146	avRandom()
dirkx	0:a259777c45a3	147	{
dirkx	0:a259777c45a3	148	u32_t newRand;
dirkx	0:a259777c45a3	149
dirkx	0:a259777c45a3	150	avGenRand((char *)&newRand, sizeof(newRand));
dirkx	0:a259777c45a3	151
dirkx	0:a259777c45a3	152	return newRand;
dirkx	0:a259777c45a3	153	}
dirkx	0:a259777c45a3	154
dirkx	0:a259777c45a3	155	#else /* MD5_SUPPORT */
dirkx	0:a259777c45a3	156
dirkx	0:a259777c45a3	157	/*****************************/
dirkx	0:a259777c45a3	158	/* LOCAL DATA STRUCTURES */
dirkx	0:a259777c45a3	159	/*****************************/
dirkx	0:a259777c45a3	160	static int avRandomized = 0; /* Set when truely randomized. */
dirkx	0:a259777c45a3	161	static u32_t avRandomSeed = 0; /* Seed used for random number generation. */
dirkx	0:a259777c45a3	162
dirkx	0:a259777c45a3	163
dirkx	0:a259777c45a3	164	/***********************************/
dirkx	0:a259777c45a3	165	/* PUBLIC FUNCTION DEFINITIONS */
dirkx	0:a259777c45a3	166	/***********************************/
dirkx	0:a259777c45a3	167	/*
dirkx	0:a259777c45a3	168	* Initialize the random number generator.
dirkx	0:a259777c45a3	169	*
dirkx	0:a259777c45a3	170	* Here we attempt to compute a random number seed but even if
dirkx	0:a259777c45a3	171	* it isn't random, we'll randomize it later.
dirkx	0:a259777c45a3	172	*
dirkx	0:a259777c45a3	173	* The current method uses the fields from the real time clock,
dirkx	0:a259777c45a3	174	* the idle process counter, the millisecond counter, and the
dirkx	0:a259777c45a3	175	* hardware timer tick counter. When this is invoked
dirkx	0:a259777c45a3	176	* in startup(), then the idle counter and timer values may
dirkx	0:a259777c45a3	177	* repeat after each boot and the real time clock may not be
dirkx	0:a259777c45a3	178	* operational. Thus we call it again on the first random
dirkx	0:a259777c45a3	179	* event.
dirkx	0:a259777c45a3	180	*/
dirkx	0:a259777c45a3	181	void
dirkx	0:a259777c45a3	182	avRandomInit()
dirkx	0:a259777c45a3	183	{
dirkx	0:a259777c45a3	184	#if 0
dirkx	0:a259777c45a3	185	/* Get a pointer into the last 4 bytes of clockBuf. */
dirkx	0:a259777c45a3	186	u32_t lptr1 = (u32_t )((char *)&clockBuf[3]);
dirkx	0:a259777c45a3	187
dirkx	0:a259777c45a3	188	/*
dirkx	0:a259777c45a3	189	* Initialize our seed using the real-time clock, the idle
dirkx	0:a259777c45a3	190	* counter, the millisecond timer, and the hardware timer
dirkx	0:a259777c45a3	191	* tick counter. The real-time clock and the hardware
dirkx	0:a259777c45a3	192	* tick counter are the best sources of randomness but
dirkx	0:a259777c45a3	193	* since the tick counter is only 16 bit (and truncated
dirkx	0:a259777c45a3	194	* at that), the idle counter and millisecond timer
dirkx	0:a259777c45a3	195	* (which may be small values) are added to help
dirkx	0:a259777c45a3	196	* randomize the lower 16 bits of the seed.
dirkx	0:a259777c45a3	197	*/
dirkx	0:a259777c45a3	198	readClk();
dirkx	0:a259777c45a3	199	avRandomSeed += (u32_t )clockBuf + *lptr1 + OSIdleCtr
dirkx	0:a259777c45a3	200	+ ppp_mtime() + ((u32_t)TM1 << 16) + TM1;
dirkx	0:a259777c45a3	201	#else
dirkx	0:a259777c45a3	202	avRandomSeed += sys_jiffies(); /* XXX */
dirkx	0:a259777c45a3	203	#endif
dirkx	0:a259777c45a3	204
dirkx	0:a259777c45a3	205	/* Initialize the Borland random number generator. */
dirkx	0:a259777c45a3	206	srand((unsigned)avRandomSeed);
dirkx	0:a259777c45a3	207	}
dirkx	0:a259777c45a3	208
dirkx	0:a259777c45a3	209	/*
dirkx	0:a259777c45a3	210	* Randomize our random seed value. Here we use the fact that
dirkx	0:a259777c45a3	211	* this function is called at truely random times by the polling
dirkx	0:a259777c45a3	212	* and network functions. Here we only get 16 bits of new random
dirkx	0:a259777c45a3	213	* value but we use the previous value to randomize the other 16
dirkx	0:a259777c45a3	214	* bits.
dirkx	0:a259777c45a3	215	*/
dirkx	0:a259777c45a3	216	void
dirkx	0:a259777c45a3	217	avRandomize(void)
dirkx	0:a259777c45a3	218	{
dirkx	0:a259777c45a3	219	static u32_t last_jiffies;
dirkx	0:a259777c45a3	220
dirkx	0:a259777c45a3	221	if (!avRandomized) {
dirkx	0:a259777c45a3	222	avRandomized = !0;
dirkx	0:a259777c45a3	223	avRandomInit();
dirkx	0:a259777c45a3	224	/* The initialization function also updates the seed. */
dirkx	0:a259777c45a3	225	} else {
dirkx	0:a259777c45a3	226	/* avRandomSeed += (avRandomSeed << 16) + TM1; */
dirkx	0:a259777c45a3	227	avRandomSeed += (sys_jiffies() - last_jiffies); /* XXX */
dirkx	0:a259777c45a3	228	}
dirkx	0:a259777c45a3	229	last_jiffies = sys_jiffies();
dirkx	0:a259777c45a3	230	}
dirkx	0:a259777c45a3	231
dirkx	0:a259777c45a3	232	/*
dirkx	0:a259777c45a3	233	* Return a new random number.
dirkx	0:a259777c45a3	234	* Here we use the Borland rand() function to supply a pseudo random
dirkx	0:a259777c45a3	235	* number which we make truely random by combining it with our own
dirkx	0:a259777c45a3	236	* seed which is randomized by truely random events.
dirkx	0:a259777c45a3	237	* Thus the numbers will be truely random unless there have been no
dirkx	0:a259777c45a3	238	* operator or network events in which case it will be pseudo random
dirkx	0:a259777c45a3	239	* seeded by the real time clock.
dirkx	0:a259777c45a3	240	*/
dirkx	0:a259777c45a3	241	u32_t
dirkx	0:a259777c45a3	242	avRandom()
dirkx	0:a259777c45a3	243	{
dirkx	0:a259777c45a3	244	return ((((u32_t)rand() << 16) + rand()) + avRandomSeed);
dirkx	0:a259777c45a3	245	}
dirkx	0:a259777c45a3	246
dirkx	0:a259777c45a3	247	#endif /* MD5_SUPPORT */
dirkx	0:a259777c45a3	248
dirkx	0:a259777c45a3	249	#endif /* PPP_SUPPORT */

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	14 Aug 2010
Imports:	49
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	2
Followers:	1

lwip/netif/ppp/randm.c@0:a259777c45a3, 2010-08-14 (annotated)

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