/*	$NetBSD: tls_prng_egd.c,v 1.2 2017/02/14 01:16:48 christos Exp $	*/

/*++
/* NAME
/*	tls_prng_egd 3
/* SUMMARY
/*	seed OpenSSL PRNG from EGD server
/* SYNOPSIS
/*	#include <tls_prng_src.h>
/*
/*	TLS_PRNG_SRC *tls_prng_egd_open(name, timeout)
/*	const char *name;
/*	int	timeout;
/*
/*	ssize_t tls_prng_egd_read(egd, length)
/*	TLS_PRNG_SRC *egd;
/*	size_t length;
/*
/*	int	tls_prng_egd_close(egd)
/*	TLS_PRNG_SRC *egd;
/* DESCRIPTION
/*	tls_prng_egd_open() connect to the specified UNIX-domain service
/*	and returns a handle that should be used with all subsequent
/*	access.
/*
/*	tls_prng_egd_read() reads the requested number of bytes from
/*	the EGD server and updates the OpenSSL PRNG.
/*
/*	tls_prng_egd_close() disconnects from the specified EGD server
/*	and releases memory that was allocated for the handle.
/*
/*	Arguments:
/* .IP name
/*	The UNIX-domain pathname of the EGD service.
/* .IP length
/*	The number of bytes to read from the EGD server.
/*	Request lengths will be truncated at 255 bytes.
/* .IP timeout
/*	Time limit on individual I/O operations.
/* DIAGNOSTICS
/*	tls_prng_egd_open() returns a null pointer on error.
/*
/*	tls_prng_egd_read() returns -1 on error, the number
/*	of bytes received on success.
/*
/*	tls_prng_egd_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 <unistd.h>
#include <limits.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_egd_open - connect to EGD server */

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

    if (msg_verbose)
	msg_info("%s: connect to EGD server %s", myname, name);

    if ((fd = unix_connect(name, BLOCKING, timeout)) < 0) {
	if (msg_verbose)
	    msg_info("%s: cannot connect to EGD server %s: %m", myname, name);
	return (0);
    } else {
	egd = (TLS_PRNG_SRC *) mymalloc(sizeof(*egd));
	egd->fd = fd;
	egd->name = mystrdup(name);
	egd->timeout = timeout;
	if (msg_verbose)
	    msg_info("%s: connected to EGD server %s", myname, name);
	return (egd);
    }
}

/* tls_prng_egd_read - update internal PRNG from EGD server */

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

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

    buffer[0] = 1;
    buffer[1] = (len > UCHAR_MAX ? UCHAR_MAX : len);

    if (timed_write(egd->fd, buffer, 2, egd->timeout, (void *) 0) != 2) {
	msg_info("cannot write to EGD server %s: %m", egd->name);
	return (-1);
    }
    if (timed_read(egd->fd, buffer, 1, egd->timeout, (void *) 0) != 1) {
	msg_info("cannot read from EGD server %s: %m", egd->name);
	return (-1);
    }
    count = buffer[0];
    if (count > sizeof(buffer))
	count = sizeof(buffer);
    if (count == 0) {
	msg_info("EGD server %s reports zero bytes available", egd->name);
	return (-1);
    }
    if (timed_read(egd->fd, buffer, count, egd->timeout, (void *) 0) != count) {
	msg_info("cannot read %ld bytes from EGD server %s: %m",
		 (long) count, egd->name);
	return (-1);
    }
    if (msg_verbose)
	msg_info("%s: got %ld bytes from EGD server %s", myname,
		 (long) count, egd->name);
    RAND_seed(buffer, count);
    return (count);
}

/* tls_prng_egd_close - disconnect from EGD server */

int     tls_prng_egd_close(TLS_PRNG_SRC *egd)
{
    const char *myname = "tls_prng_egd_close";
    int     err;

    if (msg_verbose)
	msg_info("%s: close EGD server %s", myname, egd->name);
    err = close(egd->fd);
    myfree(egd->name);
    myfree((void *) egd);
    return (err);
}

#endif