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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libc/net/res_random.c	Lines:	0	54	0.0 %
Date:	2017-11-13	Branches:	0	34	0.0 %


/* $OpenBSD: res_random.c,v 1.24 2016/04/05 04:29:21 guenther Exp $ */

/*
 * Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
 * Copyright 2008 Damien Miller <djm@openbsd.org>
 * All rights reserved.
 *
 * Theo de Raadt <deraadt@openbsd.org> came up with the idea of using
 * such a mathematical system to generate more random (yet non-repeating)
 * ids to solve the resolver/named problem.  But Niels designed the
 * actual system based on the constraints.
 *
 * Later modified by Damien Miller to wrap the LCG output in a 15-bit
 * permutation generator based on a Luby-Rackoff block cipher. This
 * ensures the output is non-repeating and preserves the MSB twiddle
 * trick, but makes it more resistant to LCG prediction.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * seed = random 15bit
 * n = prime, g0 = generator to n,
 * j = random so that gcd(j,n-1) == 1
 * g = g0^j mod n will be a generator again.
 *
 * X[0] = random seed.
 * X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator
 * with a = 7^(even random) mod m,
 *      b = random with gcd(b,m) == 1
 *      m = 31104 and a maximal period of m-1.
 *
 * The transaction id is determined by:
 * id[n] = seed xor (g^X[n] mod n)
 *
 * Effectivly the id is restricted to the lower 15 bits, thus
 * yielding two different cycles by toggling the msb on and off.
 * This avoids reuse issues caused by reseeding.
 *
 * The output of this generator is then randomly permuted though a
 * custom 15 bit Luby-Rackoff block cipher.
 */

#include <sys/types.h>
#include <netinet/in.h>
#include <sys/time.h>
#include <resolv.h>

#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#include "thread_private.h"

#define RU_OUT  	180	/* Time after wich will be reseeded */
#define RU_MAX		30000	/* Uniq cycle, avoid blackjack prediction */
#define RU_GEN		2	/* Starting generator */
#define RU_N		32749	/* RU_N-1 = 2*2*3*2729 */
#define RU_AGEN		7	/* determine ru_a as RU_AGEN^(2*rand) */
#define RU_M		31104	/* RU_M = 2^7*3^5 - don't change */
#define RU_ROUNDS	11	/* Number of rounds for permute (odd) */

struct prf_ctx {
	/* PRF lookup table for odd rounds (7 bits input to 8 bits output) */
	u_char prf7[(RU_ROUNDS / 2) * (1 << 7)];

	/* PRF lookup table for even rounds (8 bits input to 7 bits output) */
	u_char prf8[((RU_ROUNDS + 1) / 2) * (1 << 8)];
};

#define PFAC_N 3
static const u_int16_t pfacts[PFAC_N] = {
	2,
	3,
	2729
};

static u_int16_t ru_x;
static u_int16_t ru_seed, ru_seed2;
static u_int16_t ru_a, ru_b;
static u_int16_t ru_g;
static u_int16_t ru_counter = 0;
static u_int16_t ru_msb = 0;
static struct prf_ctx *ru_prf = NULL;
static time_t ru_reseed;
static pid_t ru_pid;

static u_int16_t pmod(u_int16_t, u_int16_t, u_int16_t);
static void res_initid(void);

/*
 * Do a fast modular exponation, returned value will be in the range
 * of 0 - (mod-1)
 */
static u_int16_t
pmod(u_int16_t gen, u_int16_t exp, u_int16_t mod)
{
	u_int16_t s, t, u;

	s = 1;
	t = gen;
	u = exp;

	while (u) {
		if (u & 1)
			s = (s * t) % mod;
		u >>= 1;
		t = (t * t) % mod;
	}
	return (s);
}

/*
 * 15-bit permutation based on Luby-Rackoff block cipher
 */
static u_int
permute15(u_int in)
{
	int i;
	u_int left, right, tmp;

	if (ru_prf == NULL)
		return in;

	left = (in >> 8) & 0x7f;
	right = in & 0xff;

	/*
	 * Each round swaps the width of left and right. Even rounds have
	 * a 7-bit left, odd rounds have an 8-bit left.	Since this uses an
	 * odd number of rounds, left is always 8 bits wide at the end.
	 */
	for (i = 0; i < RU_ROUNDS; i++) {
		if ((i & 1) == 0)
			tmp = ru_prf->prf8[(i << (8 - 1)) | right] & 0x7f;
		else
			tmp = ru_prf->prf7[((i - 1) << (7 - 1)) | right];
		tmp ^= left;
		left = right;
		right = tmp;
	}

	return (right << 8) | left;
}

/*
 * Initializes the seed and chooses a suitable generator. Also toggles
 * the msb flag. The msb flag is used to generate two distinct
 * cycles of random numbers and thus avoiding reuse of ids.
 *
 * This function is called from res_randomid() when needed, an
 * application does not have to worry about it.
 */
static void
res_initid(void)
{
	u_int16_t j, i;
	u_int32_t tmp;
	int noprime = 1;
	struct timespec ts;

	ru_x = arc4random_uniform(RU_M);

	/* 15 bits of random seed */
	tmp = arc4random();
	ru_seed = (tmp >> 16) & 0x7FFF;
	ru_seed2 = tmp & 0x7FFF;

	/* Determine the LCG we use */
	tmp = arc4random();
	ru_b = (tmp & 0xfffe) | 1;
	ru_a = pmod(RU_AGEN, (tmp >> 16) & 0xfffe, RU_M);
	while (ru_b % 3 == 0)
		ru_b += 2;

	j = arc4random_uniform(RU_N);

	/*
	 * Do a fast gcd(j,RU_N-1), so we can find a j with
	 * gcd(j, RU_N-1) == 1, giving a new generator for
	 * RU_GEN^j mod RU_N
	 */

	while (noprime) {
		for (i = 0; i < PFAC_N; i++)
			if (j % pfacts[i] == 0)
				break;

		if (i >= PFAC_N)
			noprime = 0;
		else
			j = (j + 1) % RU_N;
	}

	ru_g = pmod(RU_GEN, j, RU_N);
	ru_counter = 0;

	/* Initialise PRF for Luby-Rackoff permutation */
	if (ru_prf == NULL)
		ru_prf = malloc(sizeof(*ru_prf));
	if (ru_prf != NULL)
		arc4random_buf(ru_prf, sizeof(*ru_prf));

	clock_gettime(CLOCK_MONOTONIC, &ts);
	ru_reseed = ts.tv_sec + RU_OUT;
	ru_msb = ru_msb == 0x8000 ? 0 : 0x8000;
}

u_int
__res_randomid(void)
{
	struct timespec ts;
	pid_t pid;
	u_int r;
	static void *randomid_mutex;

	clock_gettime(CLOCK_MONOTONIC, &ts);
	pid = getpid();

	_MUTEX_LOCK(&randomid_mutex);

	if (ru_counter >= RU_MAX || ts.tv_sec > ru_reseed || pid != ru_pid) {
		res_initid();
		ru_pid = pid;
	}

	/* Linear Congruential Generator */
	ru_x = (ru_a * ru_x + ru_b) % RU_M;
	ru_counter++;

	r = permute15(ru_seed ^ pmod(ru_g, ru_seed2 + ru_x, RU_N)) | ru_msb;

	_MUTEX_UNLOCK(&randomid_mutex);

	return (r);
}
DEF_STRONG(__res_randomid);

#if 0
int
main(int argc, char **argv)
{
	int i, n;
	u_int16_t wert;

	res_initid();

	printf("Generator: %u\n", ru_g);
	printf("Seed: %u\n", ru_seed);
	printf("Reseed at %ld\n", ru_reseed);
	printf("Ru_X: %u\n", ru_x);
	printf("Ru_A: %u\n", ru_a);
	printf("Ru_B: %u\n", ru_b);

	n = argc > 1 ? atoi(argv[1]) : 60001;
	for (i=0;i<n;i++) {
		wert = res_randomid();
		printf("%u\n", wert);
	}
	return 0;
}
#endif



Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: res_random.c,v 1.24 2016/04/05 04:29:21 guenther Exp $ */
2
3			/*
4			* Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
5			* Copyright 2008 Damien Miller <djm@openbsd.org>
6			* All rights reserved.
7			*
8			* Theo de Raadt <deraadt@openbsd.org> came up with the idea of using
9			* such a mathematical system to generate more random (yet non-repeating)
10			* ids to solve the resolver/named problem. But Niels designed the
11			* actual system based on the constraints.
12			*
13			* Later modified by Damien Miller to wrap the LCG output in a 15-bit
14			* permutation generator based on a Luby-Rackoff block cipher. This
15			* ensures the output is non-repeating and preserves the MSB twiddle
16			* trick, but makes it more resistant to LCG prediction.
17			*
18			* Redistribution and use in source and binary forms, with or without
19			* modification, are permitted provided that the following conditions
20			* are met:
21			* 1. Redistributions of source code must retain the above copyright
22			* notice, this list of conditions and the following disclaimer.
23			* 2. Redistributions in binary form must reproduce the above copyright
24			* notice, this list of conditions and the following disclaimer in the
25			* documentation and/or other materials provided with the distribution.
26			*
27			* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28			* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29			* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30			* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31			* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32			* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33			* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34			* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35			* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36			* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37			*/
38
39			/*
40			* seed = random 15bit
41			* n = prime, g0 = generator to n,
42			* j = random so that gcd(j,n-1) == 1
43			* g = g0^j mod n will be a generator again.
44			*
45			* X[0] = random seed.
46			* X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator
47			* with a = 7^(even random) mod m,
48			* b = random with gcd(b,m) == 1
49			* m = 31104 and a maximal period of m-1.
50			*
51			* The transaction id is determined by:
52			* id[n] = seed xor (g^X[n] mod n)
53			*
54			* Effectivly the id is restricted to the lower 15 bits, thus
55			* yielding two different cycles by toggling the msb on and off.
56			* This avoids reuse issues caused by reseeding.
57			*
58			* The output of this generator is then randomly permuted though a
59			* custom 15 bit Luby-Rackoff block cipher.
60			*/
61
62			#include <sys/types.h>
63			#include <netinet/in.h>
64			#include <sys/time.h>
65			#include <resolv.h>
66
67			#include <unistd.h>
68			#include <stdlib.h>
69			#include <string.h>
70
71			#include "thread_private.h"
72
73			#define RU_OUT 180 /* Time after wich will be reseeded */
74			#define RU_MAX 30000 /* Uniq cycle, avoid blackjack prediction */
75			#define RU_GEN 2 /* Starting generator */
76			#define RU_N 32749 /* RU_N-1 = 2232729 /
77			#define RU_AGEN 7 /* determine ru_a as RU_AGEN^(2rand) /
78			#define RU_M 31104 /* RU_M = 2^73^5 - don't change /
79			#define RU_ROUNDS 11 /* Number of rounds for permute (odd) */
80
81			struct prf_ctx {
82			/* PRF lookup table for odd rounds (7 bits input to 8 bits output) */
83			u_char prf7[(RU_ROUNDS / 2) * (1 << 7)];
84
85			/* PRF lookup table for even rounds (8 bits input to 7 bits output) */
86			u_char prf8[((RU_ROUNDS + 1) / 2) * (1 << 8)];
87			};
88
89			#define PFAC_N 3
90			static const u_int16_t pfacts[PFAC_N] = {
91			2,
92			3,
93			2729
94			};
95
96			static u_int16_t ru_x;
97			static u_int16_t ru_seed, ru_seed2;
98			static u_int16_t ru_a, ru_b;
99			static u_int16_t ru_g;
100			static u_int16_t ru_counter = 0;
101			static u_int16_t ru_msb = 0;
102			static struct prf_ctx *ru_prf = NULL;
103			static time_t ru_reseed;
104			static pid_t ru_pid;
105
106			static u_int16_t pmod(u_int16_t, u_int16_t, u_int16_t);
107			static void res_initid(void);
108
109			/*
110			* Do a fast modular exponation, returned value will be in the range
111			* of 0 - (mod-1)
112			*/
113			static u_int16_t
114			pmod(u_int16_t gen, u_int16_t exp, u_int16_t mod)
115			{
116			u_int16_t s, t, u;
117
118			s = 1;
119			t = gen;
120			u = exp;
121
122			while (u) {
123			if (u & 1)
124			s = (s * t) % mod;
125			u >>= 1;
126			t = (t * t) % mod;
127			}
128			return (s);
129			}
130
131			/*
132			* 15-bit permutation based on Luby-Rackoff block cipher
133			*/
134			static u_int
135			permute15(u_int in)
136			{
137			int i;
138			u_int left, right, tmp;
139
140			if (ru_prf == NULL)
141			return in;
142
143			left = (in >> 8) & 0x7f;
144			right = in & 0xff;
145
146			/*
147			* Each round swaps the width of left and right. Even rounds have
148			* a 7-bit left, odd rounds have an 8-bit left. Since this uses an
149			* odd number of rounds, left is always 8 bits wide at the end.
150			*/
151			for (i = 0; i < RU_ROUNDS; i++) {
152			if ((i & 1) == 0)
153			tmp = ru_prf->prf8[(i << (8 - 1)) \| right] & 0x7f;
154			else
155			tmp = ru_prf->prf7[((i - 1) << (7 - 1)) \| right];
156			tmp ^= left;
157			left = right;
158			right = tmp;
159			}
160
161			return (right << 8) \| left;
162			}
163
164			/*
165			* Initializes the seed and chooses a suitable generator. Also toggles
166			* the msb flag. The msb flag is used to generate two distinct
167			* cycles of random numbers and thus avoiding reuse of ids.
168			*
169			* This function is called from res_randomid() when needed, an
170			* application does not have to worry about it.
171			*/
172			static void
173			res_initid(void)
174			{
175			u_int16_t j, i;
176			u_int32_t tmp;
177			int noprime = 1;
178			struct timespec ts;
179
180			ru_x = arc4random_uniform(RU_M);
181
182			/* 15 bits of random seed */
183			tmp = arc4random();
184			ru_seed = (tmp >> 16) & 0x7FFF;
185			ru_seed2 = tmp & 0x7FFF;
186
187			/* Determine the LCG we use */
188			tmp = arc4random();
189			ru_b = (tmp & 0xfffe) \| 1;
190			ru_a = pmod(RU_AGEN, (tmp >> 16) & 0xfffe, RU_M);
191			while (ru_b % 3 == 0)
192			ru_b += 2;
193
194			j = arc4random_uniform(RU_N);
195
196			/*
197			* Do a fast gcd(j,RU_N-1), so we can find a j with
198			* gcd(j, RU_N-1) == 1, giving a new generator for
199			* RU_GEN^j mod RU_N
200			*/
201
202			while (noprime) {
203			for (i = 0; i < PFAC_N; i++)
204			if (j % pfacts[i] == 0)
205			break;
206
207			if (i >= PFAC_N)
208			noprime = 0;
209			else
210			j = (j + 1) % RU_N;
211			}
212
213			ru_g = pmod(RU_GEN, j, RU_N);
214			ru_counter = 0;
215
216			/* Initialise PRF for Luby-Rackoff permutation */
217			if (ru_prf == NULL)
218			ru_prf = malloc(sizeof(*ru_prf));
219			if (ru_prf != NULL)
220			arc4random_buf(ru_prf, sizeof(*ru_prf));
221
222			clock_gettime(CLOCK_MONOTONIC, &ts);
223			ru_reseed = ts.tv_sec + RU_OUT;
224			ru_msb = ru_msb == 0x8000 ? 0 : 0x8000;
225			}
226
227			u_int
228			__res_randomid(void)
229			{
230			struct timespec ts;
231			pid_t pid;
232			u_int r;
233			static void *randomid_mutex;
234
235			clock_gettime(CLOCK_MONOTONIC, &ts);
236			pid = getpid();
237
238			_MUTEX_LOCK(&randomid_mutex);
239
240			if (ru_counter >= RU_MAX \|\| ts.tv_sec > ru_reseed \|\| pid != ru_pid) {
241			res_initid();
242			ru_pid = pid;
243			}
244
245			/* Linear Congruential Generator */
246			ru_x = (ru_a * ru_x + ru_b) % RU_M;
247			ru_counter++;
248
249			r = permute15(ru_seed ^ pmod(ru_g, ru_seed2 + ru_x, RU_N)) \| ru_msb;
250
251			_MUTEX_UNLOCK(&randomid_mutex);
252
253			return (r);
254			}
255			DEF_STRONG(__res_randomid);
256
257			#if 0
258			int
259			main(int argc, char **argv)
260			{
261			int i, n;
262			u_int16_t wert;
263
264			res_initid();
265
266			printf("Generator: %u\n", ru_g);
267			printf("Seed: %u\n", ru_seed);
268			printf("Reseed at %ld\n", ru_reseed);
269			printf("Ru_X: %u\n", ru_x);
270			printf("Ru_A: %u\n", ru_a);
271			printf("Ru_B: %u\n", ru_b);
272
273			n = argc > 1 ? atoi(argv[1]) : 60001;
274			for (i=0;i<n;i++) {
275			wert = res_randomid();
276			printf("%u\n", wert);
277			}
278			return 0;
279			}
280			#endif
281