mirror of
https://github.com/samba-team/samba.git
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dc1fc3ee8e
(This used to be commit 2d0922b0ea
)
268 lines
6.6 KiB
C
268 lines
6.6 KiB
C
/*
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Unix SMB/Netbios implementation.
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Version 2.2
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Functions to create reasonable random numbers for crypto use.
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Copyright (C) Jeremy Allison 2001
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "includes.h"
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static unsigned char hash[258];
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static uint32 counter;
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unsigned char *reseed_data;
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size_t reseed_data_size;
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/****************************************************************
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Copy any user given reseed data.
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*****************************************************************/
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void set_rand_reseed_data(unsigned char *data, size_t len)
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{
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SAFE_FREE(reseed_data);
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reseed_data_size = 0;
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reseed_data = (unsigned char *)memdup(data, len);
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if (reseed_data)
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reseed_data_size = len;
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}
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/****************************************************************
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Setup the seed.
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*****************************************************************/
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static void seed_random_stream(unsigned char *seedval, size_t seedlen)
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{
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unsigned char j = 0;
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size_t ind;
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for (ind = 0; ind < 256; ind++)
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hash[ind] = (unsigned char)ind;
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for( ind = 0; ind < 256; ind++) {
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unsigned char tc;
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j += (hash[ind] + seedval[ind%seedlen]);
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tc = hash[ind];
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hash[ind] = hash[j];
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hash[j] = tc;
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}
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hash[256] = 0;
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hash[257] = 0;
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}
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/****************************************************************
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Get datasize bytes worth of random data.
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*****************************************************************/
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static void get_random_stream(unsigned char *data, size_t datasize)
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{
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unsigned char index_i = hash[256];
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unsigned char index_j = hash[257];
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size_t ind;
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for( ind = 0; ind < datasize; ind++) {
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unsigned char tc;
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unsigned char t;
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index_i++;
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index_j += hash[index_i];
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tc = hash[index_i];
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hash[index_i] = hash[index_j];
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hash[index_j] = tc;
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t = hash[index_i] + hash[index_j];
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data[ind] = hash[t];
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}
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hash[256] = index_i;
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hash[257] = index_j;
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}
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/****************************************************************
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Get a 16 byte hash from the contents of a file.
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Note that the hash is not initialised.
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*****************************************************************/
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static void do_filehash(char *fname, unsigned char *the_hash)
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{
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unsigned char buf[1011]; /* deliberate weird size */
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unsigned char tmp_md4[16];
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int fd, n;
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fd = sys_open(fname,O_RDONLY,0);
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if (fd == -1)
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return;
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while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
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mdfour(tmp_md4, buf, n);
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for (n=0;n<16;n++)
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the_hash[n] ^= tmp_md4[n];
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}
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close(fd);
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}
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/**************************************************************
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Try and get a good random number seed. Try a number of
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different factors. Firstly, try /dev/urandom - use if exists.
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We use /dev/urandom as a read of /dev/random can block if
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the entropy pool dries up. This leads clients to timeout
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or be very slow on connect.
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If we can't use /dev/urandom then seed the stream random generator
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above...
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**************************************************************/
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static int do_reseed(BOOL use_fd, int fd)
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{
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unsigned char seed_inbuf[40];
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uint32 v1, v2; struct timeval tval; pid_t mypid;
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struct passwd *pw;
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if (use_fd) {
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if (fd != -1)
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return fd;
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fd = sys_open( "/dev/urandom", O_RDONLY,0);
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if(fd >= 0)
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return fd;
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}
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/* Add in some secret file contents */
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do_filehash("/etc/shadow", &seed_inbuf[0]);
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do_filehash(lp_smb_passwd_file(), &seed_inbuf[16]);
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/*
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* Add in the root encrypted password.
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* On any system where security is taken
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* seriously this will be secret.
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*/
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pw = sys_getpwnam("root");
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if (pw && pw->pw_passwd) {
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size_t i;
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unsigned char md4_tmp[16];
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mdfour(md4_tmp, (unsigned char *)pw->pw_passwd, strlen(pw->pw_passwd));
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for (i=0;i<16;i++)
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seed_inbuf[8+i] ^= md4_tmp[i];
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}
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/*
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* Add the counter, time of day, and pid.
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*/
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GetTimeOfDay(&tval);
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mypid = sys_getpid();
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v1 = (counter++) + mypid + tval.tv_sec;
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v2 = (counter++) * mypid + tval.tv_usec;
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SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32));
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SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36));
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/*
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* Add any user-given reseed data.
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*/
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if (reseed_data) {
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size_t i;
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for (i = 0; i < sizeof(seed_inbuf); i++)
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seed_inbuf[i] ^= reseed_data[i % reseed_data_size];
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}
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seed_random_stream(seed_inbuf, sizeof(seed_inbuf));
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return -1;
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}
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/*******************************************************************
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Interface to the (hopefully) good crypto random number generator.
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********************************************************************/
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void generate_random_buffer( unsigned char *out, int len, BOOL do_reseed_now)
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{
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static BOOL done_reseed = False;
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static int urand_fd = -1;
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unsigned char md4_buf[64];
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unsigned char tmp_buf[16];
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unsigned char *p;
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if(!done_reseed || do_reseed_now) {
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urand_fd = do_reseed(True, urand_fd);
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done_reseed = True;
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}
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if (urand_fd != -1 && len > 0) {
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if (read(urand_fd, out, len) == len)
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return; /* len bytes of random data read from urandom. */
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/* Read of urand error, drop back to non urand method. */
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close(urand_fd);
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urand_fd = -1;
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do_reseed(False, -1);
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done_reseed = True;
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}
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/*
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* Generate random numbers in chunks of 64 bytes,
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* then md4 them & copy to the output buffer.
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* This way the raw state of the stream is never externally
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* seen.
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*/
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p = out;
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while(len > 0) {
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int copy_len = len > 16 ? 16 : len;
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get_random_stream(md4_buf, sizeof(md4_buf));
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mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
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memcpy(p, tmp_buf, copy_len);
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p += copy_len;
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len -= copy_len;
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}
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}
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/*******************************************************************
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Use the random number generator to generate a random string.
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********************************************************************/
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static char c_list[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,";
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char *generate_random_str(size_t len)
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{
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static unsigned char retstr[256];
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size_t i;
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memset(retstr, '\0', sizeof(retstr));
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if (len > sizeof(retstr)-1)
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len = sizeof(retstr) -1;
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generate_random_buffer( retstr, len, False);
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for (i = 0; i < len; i++)
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retstr[i] = c_list[ retstr[i] % sizeof(c_list) ];
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retstr[i] = '\0';
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return (char *)retstr;
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}
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