/* 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.]
 */

#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>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#undef BUFSIZE
#define BUFSIZE	1024
#define RAND_DATA 1024

/* #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)
	{
	return(0);
	}

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 (S_ISBLK(sb.st_mode) || S_ISCHR(sb.st_mode)) {
	    /* 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); 
	  }
	}

	{
	/* chmod(..., 0600) is too late to protect the file,
	 * permissions should be restrictive from the start */
	int fd = open(file, O_WRONLY|O_CREAT, 0600);
	if (fd != -1)
		out = fdopen(fd, "wb");
	}

	if (out == NULL)
		out = fopen(file,"wb");
	if (out == NULL) goto err;

	chmod(file,0600);
	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;
	struct stat sb;

	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");
		if (s && *s && strlen(s)+strlen(RFILE)+2 < size)
			{
			BUF_strlcpy(buf,s,size);
			BUF_strlcat(buf,"/",size);
			BUF_strlcat(buf,RFILE,size);
			}
		else
		  	buf[0] = '\0'; /* no file name */
		}

	/* 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 (!buf[0])
		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);
		}	

	return(buf);
	}