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randfile.c

/* crypto/rand/randfile.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * 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 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 OR CONTRIBUTORS 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.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

/* We need to define this to get macros like S_IFBLK and S_IFCHR */
#define _XOPEN_SOURCE 500

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "e_os.h"
#include <openssl/crypto.h>
#include <openssl/rand.h>
#include <openssl/buffer.h>

#ifdef OPENSSL_SYS_VMS
#include <unixio.h>
#endif
#ifndef NO_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef MAC_OS_pre_X
# include <stat.h>
#else
# include <sys/stat.h>
#endif

#ifdef _WIN32
#define stat      _stat
#define chmod     _chmod
#define open      _open
#define fdopen    _fdopen
#endif

#undef BUFSIZE
#define BUFSIZE   1024
#define RAND_DATA 1024

#ifdef OPENSSL_SYS_VMS
/* This declaration is a nasty hack to get around vms' extension to fopen
 * for passing in sharing options being disabled by our /STANDARD=ANSI89 */
static FILE *(*const vms_fopen)(const char *, const char *, ...) =
    (FILE *(*)(const char *, const char *, ...))fopen;
#define VMS_OPEN_ATTRS "shr=get,put,upd,del","ctx=bin,stm","rfm=stm","rat=none","mrs=0"
#endif

/* #define RFILE ".rnd" - defined in ../../e_os.h */

/* Note that these functions are intended for seed files only.
 * Entropy devices and EGD sockets are handled in rand_unix.c */

int RAND_load_file(const char *file, long bytes)
      {
      /* If bytes >= 0, read up to 'bytes' bytes.
       * if bytes == -1, read complete file. */

      MS_STATIC unsigned char buf[BUFSIZE];
      struct stat sb;
      int i,ret=0,n;
      FILE *in;

      if (file == NULL) return(0);

      if (stat(file,&sb) < 0) return(0);
      RAND_add(&sb,sizeof(sb),0.0);
      if (bytes == 0) return(ret);

#ifdef OPENSSL_SYS_VMS
      in=vms_fopen(file,"rb",VMS_OPEN_ATTRS);
#else
      in=fopen(file,"rb");
#endif
      if (in == NULL) goto err;
#if defined(S_IFBLK) && defined(S_IFCHR)
      if (sb.st_mode & (S_IFBLK | S_IFCHR)) {
        /* this file is a device. we don't want read an infinite number
         * of bytes from a random device, nor do we want to use buffered
         * I/O because we will waste system entropy. 
         */
        bytes = (bytes == -1) ? 2048 : bytes; /* ok, is 2048 enough? */
        setvbuf(in, NULL, _IONBF, 0); /* don't do buffered reads */
      }
#endif
      for (;;)
            {
            if (bytes > 0)
                  n = (bytes < BUFSIZE)?(int)bytes:BUFSIZE;
            else
                  n = BUFSIZE;
            i=fread(buf,1,n,in);
            if (i <= 0) break;
#ifdef PURIFY
            RAND_add(buf,i,(double)i);
#else
            /* even if n != i, use the full array */
            RAND_add(buf,n,(double)i);
#endif
            ret+=i;
            if (bytes > 0)
                  {
                  bytes-=n;
                  if (bytes <= 0) break;
                  }
            }
      fclose(in);
      OPENSSL_cleanse(buf,BUFSIZE);
err:
      return(ret);
      }

int RAND_write_file(const char *file)
      {
      unsigned char buf[BUFSIZE];
      int i,ret=0,rand_err=0;
      FILE *out = NULL;
      int n;
      struct stat sb;
      
      i=stat(file,&sb);
      if (i != -1) { 
#if defined(S_IFBLK) && defined(S_IFCHR)
        if (sb.st_mode & (S_IFBLK | S_IFCHR)) {
          /* this file is a device. we don't write back to it. 
           * we "succeed" on the assumption this is some sort 
           * of random device. Otherwise attempting to write to 
           * and chmod the device causes problems.
           */
          return(1); 
        }
#endif
      }

#if defined(O_CREAT) && !defined(OPENSSL_SYS_WIN32) && !defined(OPENSSL_SYS_VMS)
      {
      /* For some reason Win32 can't write to files created this way */
      
      /* chmod(..., 0600) is too late to protect the file,
       * permissions should be restrictive from the start */
      int fd = open(file, O_CREAT, 0600);
      if (fd != -1)
            out = fdopen(fd, "wb");
      }
#endif

#ifdef OPENSSL_SYS_VMS
      /* VMS NOTE: Prior versions of this routine created a _new_
       * version of the rand file for each call into this routine, then
       * deleted all existing versions named ;-1, and finally renamed
       * the current version as ';1'. Under concurrent usage, this
       * resulted in an RMS race condition in rename() which could
       * orphan files (see vms message help for RMS$_REENT). With the
       * fopen() calls below, openssl/VMS now shares the top-level
       * version of the rand file. Note that there may still be
       * conditions where the top-level rand file is locked. If so, this
       * code will then create a new version of the rand file. Without
       * the delete and rename code, this can result in ascending file
       * versions that stop at version 32767, and this routine will then
       * return an error. The remedy for this is to recode the calling
       * application to avoid concurrent use of the rand file, or
       * synchronize usage at the application level. Also consider
       * whether or not you NEED a persistent rand file in a concurrent
       * use situation. 
       */

      out = vms_fopen(file,"rb+",VMS_OPEN_ATTRS);
      if (out == NULL)
            out = vms_fopen(file,"wb",VMS_OPEN_ATTRS);
#else
      if (out == NULL)
            out = fopen(file,"wb");
#endif
      if (out == NULL) goto err;

#ifndef NO_CHMOD
      chmod(file,0600);
#endif
      n=RAND_DATA;
      for (;;)
            {
            i=(n > BUFSIZE)?BUFSIZE:n;
            n-=BUFSIZE;
            if (RAND_bytes(buf,i) <= 0)
                  rand_err=1;
            i=fwrite(buf,1,i,out);
            if (i <= 0)
                  {
                  ret=0;
                  break;
                  }
            ret+=i;
            if (n <= 0) break;
                }

      fclose(out);
      OPENSSL_cleanse(buf,BUFSIZE);
err:
      return (rand_err ? -1 : ret);
      }

const char *RAND_file_name(char *buf, size_t size)
      {
      char *s=NULL;
      int ok = 0;
#ifdef __OpenBSD__
      struct stat sb;
#endif

      if (OPENSSL_issetugid() == 0)
            s=getenv("RANDFILE");
      if (s != NULL && *s && strlen(s) + 1 < size)
            {
            if (BUF_strlcpy(buf,s,size) >= size)
                  return NULL;
            }
      else
            {
            if (OPENSSL_issetugid() == 0)
                  s=getenv("HOME");
#ifdef DEFAULT_HOME
            if (s == NULL)
                  {
                  s = DEFAULT_HOME;
                  }
#endif
            if (s && *s && strlen(s)+strlen(RFILE)+2 < size)
                  {
                  BUF_strlcpy(buf,s,size);
#ifndef OPENSSL_SYS_VMS
                  BUF_strlcat(buf,"/",size);
#endif
                  BUF_strlcat(buf,RFILE,size);
                  ok = 1;
                  }
            else
                  buf[0] = '\0'; /* no file name */
            }

#ifdef __OpenBSD__
      /* given that all random loads just fail if the file can't be 
       * seen on a stat, we stat the file we're returning, if it
       * fails, use /dev/arandom instead. this allows the user to 
       * use their own source for good random data, but defaults
       * to something hopefully decent if that isn't available. 
       */

      if (!ok)
            if (BUF_strlcpy(buf,"/dev/arandom",size) >= size) {
                  return(NULL);
            }     
      if (stat(buf,&sb) == -1)
            if (BUF_strlcpy(buf,"/dev/arandom",size) >= size) {
                  return(NULL);
            }     

#endif
      return(buf);
      }

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