/***************************************************************************
* nbase_rnd.c -- Some simple routines for obtaining random numbers for *
* casual use. These are pretty secure on systems with /dev/urandom, but *
* falls back to poor entropy for seeding on systems without such support. *
* *
* Based on DNET / OpenBSD arc4random(). *
* *
* Copyright (c) 2000 Dug Song <dugsong@monkey.org> *
* Copyright (c) 1996 David Mazieres <dm@lcs.mit.edu> *
* *
***********************IMPORTANT NMAP LICENSE TERMS************************
* *
* The Nmap Security Scanner is (C) 1996-2009 Insecure.Com LLC. Nmap is *
* also a registered trademark of Insecure.Com LLC. This program is free *
* software; you may redistribute and/or modify it under the terms of the *
* GNU General Public License as published by the Free Software *
* Foundation; Version 2 with the clarifications and exceptions described *
* below. This guarantees your right to use, modify, and redistribute *
* this software under certain conditions. If you wish to embed Nmap *
* technology into proprietary software, we sell alternative licenses *
* (contact sales@insecure.com). Dozens of software vendors already *
* license Nmap technology such as host discovery, port scanning, OS *
* detection, and version detection. *
* *
* Note that the GPL places important restrictions on "derived works", yet *
* it does not provide a detailed definition of that term. To avoid *
* misunderstandings, we consider an application to constitute a *
* "derivative work" for the purpose of this license if it does any of the *
* following: *
* o Integrates source code from Nmap *
* o Reads or includes Nmap copyrighted data files, such as *
* nmap-os-db or nmap-service-probes. *
* o Executes Nmap and parses the results (as opposed to typical shell or *
* execution-menu apps, which simply display raw Nmap output and so are *
* not derivative works.) *
* o Integrates/includes/aggregates Nmap into a proprietary executable *
* installer, such as those produced by InstallShield. *
* o Links to a library or executes a program that does any of the above *
* *
* The term "Nmap" should be taken to also include any portions or derived *
* works of Nmap. This list is not exclusive, but is meant to clarify our *
* interpretation of derived works with some common examples. Our *
* interpretation applies only to Nmap--we don't speak for other people's *
* GPL works. *
* *
* If you have any questions about the GPL licensing restrictions on using *
* Nmap in non-GPL works, we would be happy to help. As mentioned above, *
* we also offer alternative license to integrate Nmap into proprietary *
* applications and appliances. These contracts have been sold to dozens *
* of software vendors, and generally include a perpetual license as well *
* as providing for priority support and updates as well as helping to *
* fund the continued development of Nmap technology. Please email *
* sales@insecure.com for further information. *
* *
* As a special exception to the GPL terms, Insecure.Com LLC grants *
* permission to link the code of this program with any version of the *
* OpenSSL library which is distributed under a license identical to that *
* listed in the included COPYING.OpenSSL file, and distribute linked *
* combinations including the two. You must obey the GNU GPL in all *
* respects for all of the code used other than OpenSSL. If you modify *
* this file, you may extend this exception to your version of the file, *
* but you are not obligated to do so. *
* *
* If you received these files with a written license agreement or *
* contract stating terms other than the terms above, then that *
* alternative license agreement takes precedence over these comments. *
* *
* Source is provided to this software because we believe users have a *
* right to know exactly what a program is going to do before they run it. *
* This also allows you to audit the software for security holes (none *
* have been found so far). *
* *
* Source code also allows you to port Nmap to new platforms, fix bugs, *
* and add new features. You are highly encouraged to send your changes *
* to nmap-dev@insecure.org for possible incorporation into the main *
* distribution. By sending these changes to Fyodor or one of the *
* Insecure.Org development mailing lists, it is assumed that you are *
* offering the Nmap Project (Insecure.Com LLC) the unlimited, *
* non-exclusive right to reuse, modify, and relicense the code. Nmap *
* will always be available Open Source, but this is important because the *
* inability to relicense code has caused devastating problems for other *
* Free Software projects (such as KDE and NASM). We also occasionally *
* relicense the code to third parties as discussed above. If you wish to *
* specify special license conditions of your contributions, just say so *
* when you send them. *
* *
* This program is distributed in the hope that it will be useful, but *
* WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* General Public License v2.0 for more details at *
* http://www.gnu.org/licenses/gpl-2.0.html , or in the COPYING file *
* included with Nmap. *
* *
***************************************************************************/
/* $Id: nbase_rnd.c 12956 2009-04-15 00:37:23Z fyodor $ */
#include "nbase.h"
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#if HAVE_SYS_TIME_H
#include <sys/time.h>
#endif /* HAV_SYS_TIME_H */
#ifdef WIN32
#include <wincrypt.h>
#endif /* WIN32 */
/* data for our random state */
struct nrand_handle {
u8 i, j, s[256], *tmp;
int tmplen;
};
typedef struct nrand_handle nrand_h;
static void nrand_addrandom(nrand_h *rand, u8 *buf, int len) {
int i;
u8 si;
/* Mix entropy in buf with s[]...
*
* This is the ARC4 key-schedule. It is rather poor and doesn't mix
* the key in very well. This causes a bias at the start of the stream.
* To eliminate most of this bias, the first N bytes of the stream should
* be dropped.
*/
rand->i--;
for (i = 0; i < 256; i++) {
rand->i = (rand->i + 1);
si = rand->s[rand->i];
rand->j = (rand->j + si + buf[i % len]);
rand->s[rand->i] = rand->s[rand->j];
rand->s[rand->j] = si;
}
rand->j = rand->i;
}
static u8 nrand_getbyte(nrand_h *r) {
u8 si, sj;
/* This is the core of ARC4 and provides the pseudo-randomness */
r->i = (r->i + 1);
si = r->s[r->i];
r->j = (r->j + si);
sj = r->s[r->j];
r->s[r->i] = sj; /* The start of the the swap */
r->s[r->j] = si; /* The other half of the swap */
return (r->s[(si + sj) & 0xff]);
}
int nrand_get(nrand_h *r, void *buf, size_t len) {
u8 *p;
size_t i;
/* Hand out however many bytes were asked for */
for (p = buf, i = 0; i < len; i++) {
p[i] = nrand_getbyte(r);
}
return (0);
}
void nrand_init(nrand_h *r) {
u8 seed[256]; /* Starts out with "random" stack data */
int i;
/* Gather seed entropy with best the OS has to offer */
#ifdef WIN32
HCRYPTPROV hcrypt = 0;
CryptAcquireContext(&hcrypt, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
CryptGenRandom(hcrypt, sizeof(seed), seed);
CryptReleaseContext(hcrypt, 0);
#else
struct timeval *tv = (struct timeval *)seed;
int *pid = (int *)(seed + sizeof(*tv));
int fd;
gettimeofday(tv, NULL); /* fill lowest seed[] with time */
*pid = getpid(); /* fill next lowest seed[] with pid */
/* Try to fill the rest of the state with OS provided entropy */
if ((fd = open("/dev/urandom", O_RDONLY)) != -1 ||
(fd = open("/dev/arandom", O_RDONLY)) != -1) {
ssize_t n;
do {
errno = 0;
n = read(fd, seed + sizeof(*tv) + sizeof(*pid),
sizeof(seed) - sizeof(*tv) - sizeof(*pid));
} while (n < 0 && errno == EINTR);
close(fd);
}
#endif
/* Fill up our handle with starter values */
for (i = 0; i < 256; i++) { r->s[i] = i; };
r->i = r->j = 0;
nrand_addrandom(r, seed, 128); /* lower half of seed data for entropy */
nrand_addrandom(r, seed + 128, 128); /* Now use upper half */
r->tmp = NULL;
r->tmplen = 0;
/* This stream will start biased. Get rid of 1K of the stream */
nrand_get(r, seed, 256); nrand_get(r, seed, 256);
nrand_get(r, seed, 256); nrand_get(r, seed, 256);
}
int get_random_bytes(void *buf, int numbytes) {
static nrand_h state;
static int state_init = 0;
/* Initialize if we need to */
if (!state_init) {
nrand_init(&state);
state_init = 1;
}
/* Now fill our buffer */
nrand_get(&state, buf, numbytes);
return 0;
}
int get_random_int() {
int i;
get_random_bytes(&i, sizeof(int));
return i;
}
unsigned int get_random_uint() {
unsigned int i;
get_random_bytes(&i, sizeof(unsigned int));
return i;
}
u32 get_random_u32() {
u32 i;
get_random_bytes(&i, sizeof(i));
return i;
}
u16 get_random_u16() {
u16 i;
get_random_bytes(&i, sizeof(i));
return i;
}
u8 get_random_u8() {
u8 i;
get_random_bytes(&i, sizeof(i));
return i;
}
unsigned short get_random_ushort() {
unsigned short s;
get_random_bytes(&s, sizeof(unsigned short));
return s;
}