/*++
/* NAME
/*	tls_prng_dev 3
/* SUMMARY
/*	seed OpenSSL PRNG from entropy device
/* SYNOPSIS
/*	#include <tls_prng_src.h>
/*
/*	TLS_PRNG_SRC *tls_prng_dev_open(name, timeout)
/*	const char *name;
/*	int	timeout;
/*
/*	ssize_t tls_prng_dev_read(dev, length)
/*	TLS_PRNG_SRC *dev;
/*	size_t length;
/*
/*	int	tls_prng_dev_close(dev)
/*	TLS_PRNG_SRC *dev;
/* DESCRIPTION
/*	tls_prng_dev_open() opens the specified entropy device
/*	and returns a handle that should be used with all subsequent
/*	access.
/*
/*	tls_prng_dev_read() reads the requested number of bytes from
/*	the entropy device and updates the OpenSSL PRNG.
/*
/*	tls_prng_dev_close() closes the specified entropy device 
/*	and releases memory that was allocated for the handle.
/*
/*	Arguments:
/* .IP name
/*	The pathname of the entropy device.
/* .IP length
/*	The number of bytes to read from the entropy device.
/*	Request lengths will be truncated at 255 bytes.
/* .IP timeout
/*	Time limit on individual I/O operations.
/* DIAGNOSTICS
/*	tls_prng_dev_open() returns a null pointer on error.
/*
/*	tls_prng_dev_read() returns -1 on error, the number
/*	of bytes received on success.
/*
/*	tls_prng_dev_close() returns -1 on error, 0 on success.
/*
/*	In all cases the errno variable indicates the type of error.
/* LICENSE
/* .ad
/* .fi
/*	The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*	Wietse Venema
/*	IBM T.J. Watson Research
/*	P.O. Box 704
/*	Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <fcntl.h>
#include <unistd.h>
#include <limits.h>
#include <errno.h>

#ifndef UCHAR_MAX
#define UCHAR_MAX 0xff
#endif

/* OpenSSL library. */

#ifdef USE_TLS
#include <openssl/rand.h>		/* For the PRNG */

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <connect.h>
#include <iostuff.h>

/* TLS library. */

#include <tls_prng.h>

/* tls_prng_dev_open - open entropy device */

TLS_PRNG_SRC *tls_prng_dev_open(const char *name, int timeout)
{
    const char *myname = "tls_prng_dev_open";
    TLS_PRNG_SRC *dev;
    int     fd;

    if ((fd = open(name, O_RDONLY, 0)) < 0) {
	if (msg_verbose)
	    msg_info("%s: cannot open entropy device %s: %m", myname, name);
	return (0);
    } else {
	dev = (TLS_PRNG_SRC *) mymalloc(sizeof(*dev));
	dev->fd = fd;
	dev->name = mystrdup(name);
	dev->timeout = timeout;
	if (msg_verbose)
	    msg_info("%s: opened entropy device %s", myname, name);
	return (dev);
    }
}

/* tls_prng_dev_read - update internal PRNG from device */

ssize_t tls_prng_dev_read(TLS_PRNG_SRC *dev, size_t len)
{
    const char *myname = "tls_prng_dev_read";
    unsigned char buffer[UCHAR_MAX];
    ssize_t count;
    size_t  rand_bytes;

    if (len <= 0)
	msg_panic("%s: bad read length: %ld", myname, (long) len);

    if (len > sizeof(buffer))
	rand_bytes = sizeof(buffer);
    else
	rand_bytes = len;
    errno = 0;
    count = timed_read(dev->fd, buffer, rand_bytes, dev->timeout, (void *) 0);
    if (count > 0) {
	if (msg_verbose)
	    msg_info("%s: read %ld bytes from entropy device %s",
		     myname, (long) count, dev->name);
	RAND_seed(buffer, count);
    } else {
	if (msg_verbose)
	    msg_info("%s: cannot read %ld bytes from entropy device %s: %m",
		     myname, (long) rand_bytes, dev->name);
    }
    return (count);
}

/* tls_prng_dev_close - disconnect from EGD server */

int     tls_prng_dev_close(TLS_PRNG_SRC *dev)
{
    const char *myname = "tls_prng_dev_close";
    int     err;

    if (msg_verbose)
	msg_info("%s: close entropy device %s", myname, dev->name);
    err = close(dev->fd);
    myfree(dev->name);
    myfree((char *) dev);
    return (err);
}

#endif
