/*	$NetBSD: tls_session.c,v 1.3 2020/05/25 23:47:14 christos Exp $	*/

/*++
/* NAME
/*	tls_session
/* SUMMARY
/*	TLS client and server session routines
/* SYNOPSIS
/*	#include <tls.h>
/*
/*	void	tls_session_stop(ctx, stream, timeout, failure, TLScontext)
/*	TLS_APPL_STATE *ctx;
/*	VSTREAM	*stream;
/*	int	timeout;
/*	int	failure;
/*	TLS_SESS_STATE *TLScontext;
/*
/*	VSTRING	*tls_session_passivate(session)
/*	SSL_SESSION *session;
/*
/*	SSL_SESSION *tls_session_activate(session_data, session_data_len)
/*	char	*session_data;
/*	int	session_data_len;
/* DESCRIPTION
/*	tls_session_stop() implements the tls_server_shutdown()
/*	and the tls_client_shutdown() routines.
/*
/*	tls_session_passivate() converts an SSL_SESSION object to
/*	VSTRING. The result is a null pointer in case of problems,
/*	otherwise it should be disposed of with vstring_free().
/*
/*	tls_session_activate() reanimates a passivated SSL_SESSION object.
/*	The result is a null pointer in case of problems,
/*	otherwise it should be disposed of with SSL_SESSION_free().
/* LICENSE
/* .ad
/* .fi
/*	This software is free. You can do with it whatever you want.
/*	The original author kindly requests that you acknowledge
/*	the use of his software.
/* AUTHOR(S)
/*	Originally written by:
/*	Lutz Jaenicke
/*	BTU Cottbus
/*	Allgemeine Elektrotechnik
/*	Universitaetsplatz 3-4
/*	D-03044 Cottbus, Germany
/*
/*	Updated by:
/*	Wietse Venema
/*	IBM T.J. Watson Research
/*	P.O. Box 704
/*	Yorktown Heights, NY 10598, USA
/*
/*	Wietse Venema
/*	Google, Inc.
/*	111 8th Avenue
/*	New York, NY 10011, USA
/*
/*	Victor Duchovni
/*	Morgan Stanley
/*--*/

/* System library. */

#include <sys_defs.h>

#ifdef USE_TLS

/* Utility library. */

#include <vstream.h>
#include <msg.h>
#include <mymalloc.h>

/* Global library. */

#include <mail_params.h>

/* TLS library. */

#define TLS_INTERNAL
#include <tls.h>

/* Application-specific. */

#define STR	vstring_str

/* tls_session_stop - shut down the TLS connection and reset state */

void    tls_session_stop(TLS_APPL_STATE *unused_ctx, VSTREAM *stream, int timeout,
			         int failure, TLS_SESS_STATE *TLScontext)
{
    const char *myname = "tls_session_stop";
    int     retval;

    /*
     * Sanity check.
     */
    if (TLScontext == 0)
	msg_panic("%s: stream has no active TLS context", myname);

    /*
     * According to RFC 2246 (TLS 1.0), there is no requirement to wait for
     * the peer's close-notify. If the application protocol provides
     * sufficient session termination signaling, then there's no need to
     * duplicate that at the TLS close-notify layer.
     * 
     * https://tools.ietf.org/html/rfc2246#section-7.2.1
     * https://tools.ietf.org/html/rfc4346#section-7.2.1
     * https://tools.ietf.org/html/rfc5246#section-7.2.1
     * 
     * Specify 'tls_fast_shutdown = no' to enable the historical behavior
     * described below.
     * 
     * Perform SSL_shutdown() twice, as the first attempt will send out the
     * shutdown alert but it will not wait for the peer's shutdown alert.
     * Therefore, when we are the first party to send the alert, we must call
     * SSL_shutdown() again. On failure we don't want to resume the session,
     * so we will not perform SSL_shutdown() and the session will be removed
     * as being bad.
     */
    if (!failure && !SSL_in_init(TLScontext->con)) {
	retval = tls_bio_shutdown(vstream_fileno(stream), timeout, TLScontext);
	if (!var_tls_fast_shutdown && retval == 0)
	    tls_bio_shutdown(vstream_fileno(stream), timeout, TLScontext);
    }
    tls_free_context(TLScontext);
    tls_stream_stop(stream);
}

/* tls_session_passivate - passivate SSL_SESSION object */

VSTRING *tls_session_passivate(SSL_SESSION *session)
{
    const char *myname = "tls_session_passivate";
    int     estimate;
    int     actual_size;
    VSTRING *session_data;
    unsigned char *ptr;

    /*
     * First, find out how much memory is needed for the passivated
     * SSL_SESSION object.
     */
    estimate = i2d_SSL_SESSION(session, (unsigned char **) 0);
    if (estimate <= 0) {
	msg_warn("%s: i2d_SSL_SESSION failed: unable to cache session", myname);
	return (0);
    }

    /*
     * Passivate the SSL_SESSION object. The use of a VSTRING is slightly
     * wasteful but is convenient to combine data and length.
     */
    session_data = vstring_alloc(estimate);
    ptr = (unsigned char *) STR(session_data);
    actual_size = i2d_SSL_SESSION(session, &ptr);
    if (actual_size != estimate) {
	msg_warn("%s: i2d_SSL_SESSION failed: unable to cache session", myname);
	vstring_free(session_data);
	return (0);
    }
    vstring_set_payload_size(session_data, actual_size);

    return (session_data);
}

/* tls_session_activate - activate passivated session */

SSL_SESSION *tls_session_activate(const char *session_data, int session_data_len)
{
    SSL_SESSION *session;
    const unsigned char *ptr;

    /*
     * Activate the SSL_SESSION object.
     */
    ptr = (const unsigned char *) session_data;
    session = d2i_SSL_SESSION((SSL_SESSION **) 0, &ptr, session_data_len);
    if (!session)
	tls_print_errors();

    return (session);
}

#endif