/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */

/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * t_rcv.c and t_rcvv.c are very similar and contain common code.
 * Any changes to either of them should be reviewed to see whether they
 * are applicable to the other file.
 */
#include "mt.h"
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <stropts.h>
#include <sys/stream.h>
#define _SUN_TPI_VERSION 2
#include <sys/tihdr.h>
#include <sys/timod.h>
#include <xti.h>
#include <syslog.h>
#include <assert.h>
#include "tx.h"

int
_tx_rcv(int fd, char *buf, unsigned nbytes, int *flags, int api_semantics)
{
        struct strbuf ctlbuf, databuf;
        int retval, flg = 0;
        int msglen;
        union T_primitives *pptr;
        struct _ti_user *tiptr;
        int sv_errno;
        int didalloc;

        if ((tiptr = _t_checkfd(fd, 0, api_semantics)) == NULL)
                return (-1);
        sig_mutex_lock(&tiptr->ti_lock);

        if (tiptr->ti_servtype == T_CLTS) {
                t_errno = TNOTSUPPORT;
                sig_mutex_unlock(&tiptr->ti_lock);
                return (-1);
        }

        if (_T_IS_XTI(api_semantics)) {
                /*
                 * User level state verification only done for XTI
                 * because doing for TLI may break existing applications
                 */
                if (!(tiptr->ti_state == T_DATAXFER ||
                        tiptr->ti_state == T_OUTREL)) {
                        t_errno = TOUTSTATE;
                        sig_mutex_unlock(&tiptr->ti_lock);
                        return (-1);
                }
        }

        /*
         * Check in lookbuf for stuff
         */
        if (tiptr->ti_lookcnt > 0) {
                /*
                 * Implied preference rules give priority to
                 * T_DISCON_IND over T_ORDREL_IND. Also certain errors like
                 * data received after T_ORDREL_IND or a duplicate T_ORDREL_IND
                 * after a T_ORDRELING have priority over TLOOK.
                 * This manifests in following code behavior.
                 *
                 * (1)  If something in lookbuf then check
                 *      the stream head also. This may result
                 *      in retuning a TLOOK error but only if there are
                 *        - message at stream head but look buffer
                 *          has a T_DISCON_IND event.
                 *        - no messages are on the stream head
                 *
                 * (2)  If there are messages on the stream head and
                 *      all of them are T_ORDREL_IND(i.e. no message in
                 *      look buffer is T_DISCON_IND), there
                 *      could be data on stream head to be picked up and
                 *      we work on the stream head and not return TLOOK.
                 *      We remove the event on the stream head and queue it.
                 *
                 */
                do {
                        retval = ioctl(fd, I_NREAD, &msglen);
                } while (retval < 0 && errno == EINTR);

                if (retval < 0) {
                        sv_errno = errno;

                        t_errno = TSYSERR;
                        sig_mutex_unlock(&tiptr->ti_lock);
                        errno = sv_errno;
                        return (-1);
                }

                if (retval > 0) {
                        /*
                         * If any T_DISCON_IND event in look buffer
                         * list then return TLOOK. Else continue
                         * processing as what could be on the stream
                         * head might be a possible T_DISCON_IND (which
                         * would have priority over the T_ORDREL_INDs
                         * on the look buffer.)
                         */
                        struct _ti_lookbufs *tlbs;

                        tlbs = &tiptr->ti_lookbufs;
                        do {
                                /* LINTED pointer cast */
                                if (*((t_scalar_t *)tlbs->tl_lookcbuf)
                                    == T_DISCON_IND) {
                                        t_errno = TLOOK;
                                        sig_mutex_unlock(&tiptr->ti_lock);
                                        return (-1);
                                }
                        } while ((tlbs = tlbs->tl_next) != NULL);

                } else {        /* retval == 0 */
                        /*
                         * Nothing on stream head so whatever in
                         * look buffer has nothing that might override
                         * it.
                         */
                        t_errno = TLOOK;
                        sig_mutex_unlock(&tiptr->ti_lock);
                        return (-1);
                }
        }

        /*
         * Acquire ctlbuf for use in sending/receiving control part
         * of the message.
         */
        if (_t_acquire_ctlbuf(tiptr, &ctlbuf, &didalloc) < 0) {
                sv_errno = errno;
                sig_mutex_unlock(&tiptr->ti_lock);
                errno = sv_errno;
                return (-1);
        }

        databuf.maxlen = nbytes;
        databuf.len = 0;
        databuf.buf = buf;

        *flags = 0;

        /*
         * This is a call that may block indefinitely so we drop the
         * lock and allow signals in MT case here and reacquire it.
         * Error case should roll back state changes done above
         * (happens to be no state change here)
         */
        sig_mutex_unlock(&tiptr->ti_lock);
        if ((retval = getmsg(fd, &ctlbuf, &databuf, &flg)) < 0) {
                if (errno == EAGAIN)
                        t_errno = TNODATA;
                else
                        t_errno = TSYSERR;
                sv_errno = errno;
                sig_mutex_lock(&tiptr->ti_lock);
                errno = sv_errno;
                goto err_out;
        }
        sig_mutex_lock(&tiptr->ti_lock);

        assert((retval & MORECTL) == 0); /* MORECTL should not be on */

        if (databuf.len == -1) databuf.len = 0;

        if (ctlbuf.len > 0) {
                if (ctlbuf.len < (int)sizeof (t_scalar_t)) {
                        t_errno = TSYSERR;
                        errno = EPROTO;
                        goto err_out;
                }

                /* LINTED pointer cast */
                pptr = (union T_primitives *)ctlbuf.buf;

                switch (pptr->type) {

                case T_EXDATA_IND:
                        *flags |= T_EXPEDITED;
                        if (retval > 0)
                                tiptr->ti_flags |= EXPEDITED;
                        /* FALLTHROUGH */
                case T_DATA_IND:
                        /*
                         * Uses the fact T_DATA_IND and T_EXDATA_IND
                         * are same in size
                         */
                        if ((ctlbuf.len < (int)sizeof (struct T_data_ind)) ||
                            (tiptr->ti_lookcnt > 0)) {
                                /*
                                 * ti_lookcnt > 0 implies data
                                 * received after T_DISCON_IND or
                                 * T_ORDREL_IND hence error
                                 */
                                t_errno = TSYSERR;
                                errno = EPROTO;
                                goto err_out;
                        }

                        if ((pptr->data_ind.MORE_flag) || retval)
                                *flags |= T_MORE;
                        if ((pptr->data_ind.MORE_flag) && retval)
                                tiptr->ti_flags |= MORE;
                        /*
                         * No real state change on T_RCV event (noop)
                         *
                         * We invoke the macro only for error logging
                         * part of its capabilities when in a bad state.
                         */
                        _T_TX_NEXTSTATE(T_RCV, tiptr,
                                        "t_rcv: invalid state event T_RCV");
                        if (didalloc)
                                free(ctlbuf.buf);
                        else
                                tiptr->ti_ctlbuf = ctlbuf.buf;
                        sig_mutex_unlock(&tiptr->ti_lock);
                        return (databuf.len);

                case T_ORDREL_IND:
                        if (tiptr->ti_lookcnt > 0) {
                                /*
                                 * ti_lookcnt > 0 implies T_ORDREL_IND
                                 * received after T_DISCON_IND or
                                 * another T_ORDREL_IND hence error.
                                 */
                                t_errno = TSYSERR;
                                errno = EPROTO;
                                goto err_out;
                        }
                        /* FALLTHROUGH */
                case T_DISCON_IND:
                        /*
                         * Post event (T_ORDREL_IND/T_DISCON_IND) to
                         * the lookbuffer list.
                         */

                        if (_t_register_lookevent(tiptr, databuf.buf,
                                        databuf.len,
                                        ctlbuf.buf, ctlbuf.len) < 0) {
                                t_errno = TSYSERR;
                                errno = ENOMEM;
                                goto err_out;
                        }
                        /*
                         * We know that T_DISCON_IND is stored in
                         * last look buffer. If there is more data
                         * that follows, we try to append it to
                         * the same look buffer
                         */
                        if (retval & MOREDATA) {
                                ctlbuf.maxlen = 0; /* XXX why ? */
                                ctlbuf.len = 0;

                                /*
                                 * XXX Will break (-ve maxlen) for
                                 * transport provider with unbounded
                                 * T_DISCON_IND data part (-1).
                                 */
                                databuf.maxlen =
                                        tiptr->ti_rcvsize - databuf.len;

                                databuf.len = 0;
                                databuf.buf =
                                        tiptr->ti_lookbufs.tl_lookdbuf +
                                        tiptr->ti_lookbufs.tl_lookdlen;
                                *flags = 0;

                                /*
                                 * Since MOREDATA was set, we assume
                                 * that this getmsg will not block
                                 * indefinitely
                                 */
                                do {
                                        retval = getmsg(fd, &ctlbuf,
                                                        &databuf, &flg);
                                } while (retval < 0 && errno == EINTR);

                                if (retval < 0) {
                                        t_errno = TSYSERR;
                                        goto err_out;
                                }
                                if (databuf.len == -1) databuf.len = 0;
                                if (retval > 0) {
                                        /* MORECTL should not be on */
                                        assert((retval & MORECTL) == 0);
                                        /*
                                         * XXX - Why ?
                                         * No support for unbounded data
                                         * on T_DISCON_IND ?
                                         */
                                        t_errno = TSYSERR;
                                        errno = EPROTO;
                                        goto err_out;
                                }
                                tiptr->ti_lookbufs.tl_lookdlen +=
                                        databuf.len;
                        }

                        t_errno = TLOOK;
                        goto err_out;

                default:
                        break;
                }

                t_errno = TSYSERR;
                errno = EPROTO;
                goto err_out;

        } else {                /* else for "if (ctlbuf.len > 0)" */
                if (!retval && (tiptr->ti_flags & MORE)) {
                        *flags |= T_MORE;
                        tiptr->ti_flags &= ~MORE;
                }
                if (retval & MOREDATA)
                        *flags |= T_MORE;

                /*
                 * If inside an ETSDU, set expedited flag and turn
                 * of internal version when reach end of "ETIDU".
                 */
                if (tiptr->ti_flags & EXPEDITED) {
                        *flags |= T_EXPEDITED;
                        if (!retval)
                                tiptr->ti_flags &= ~EXPEDITED;
                }

                /*
                 * No real state change on T_RCV events (It is a NOOP)
                 *
                 * We invoke the macro only for error logging
                 * part of its capabilities when in a bad state.
                 */
                _T_TX_NEXTSTATE(T_RCV, tiptr,
                        "t_rcv: state invalid T_RCV event");
                if (didalloc)
                        free(ctlbuf.buf);
                else
                        tiptr->ti_ctlbuf = ctlbuf.buf;
                sig_mutex_unlock(&tiptr->ti_lock);
                return (databuf.len);
        }
        /* NOTREACHED */

err_out:
        sv_errno = errno;
        if (didalloc)
                free(ctlbuf.buf);
        else
                tiptr->ti_ctlbuf = ctlbuf.buf;
        sig_mutex_unlock(&tiptr->ti_lock);

        errno = sv_errno;
        return (-1);
}