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Annotation of kernel/bsd/netccitt/hd_output.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /*
        !            26:  * Copyright (c) University of British Columbia, 1984
        !            27:  * Copyright (c) 1990, 1993
        !            28:  *     The Regents of the University of California.  All rights reserved.
        !            29:  *
        !            30:  * This code is derived from software contributed to Berkeley by
        !            31:  * the Laboratory for Computation Vision and the Computer Science Department
        !            32:  * of the University of British Columbia.
        !            33:  *
        !            34:  * Redistribution and use in source and binary forms, with or without
        !            35:  * modification, are permitted provided that the following conditions
        !            36:  * are met:
        !            37:  * 1. Redistributions of source code must retain the above copyright
        !            38:  *    notice, this list of conditions and the following disclaimer.
        !            39:  * 2. Redistributions in binary form must reproduce the above copyright
        !            40:  *    notice, this list of conditions and the following disclaimer in the
        !            41:  *    documentation and/or other materials provided with the distribution.
        !            42:  * 3. All advertising materials mentioning features or use of this software
        !            43:  *    must display the following acknowledgement:
        !            44:  *     This product includes software developed by the University of
        !            45:  *     California, Berkeley and its contributors.
        !            46:  * 4. Neither the name of the University nor the names of its contributors
        !            47:  *    may be used to endorse or promote products derived from this software
        !            48:  *    without specific prior written permission.
        !            49:  *
        !            50:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            51:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            52:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            53:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            54:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            55:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            56:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            57:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            58:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            59:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            60:  * SUCH DAMAGE.
        !            61:  *
        !            62:  *     @(#)hd_output.c 8.1 (Berkeley) 6/10/93
        !            63:  */
        !            64: 
        !            65: #include <sys/param.h>
        !            66: #include <sys/systm.h>
        !            67: #include <sys/mbuf.h>
        !            68: #include <sys/domain.h>
        !            69: #include <sys/socket.h>
        !            70: #include <sys/syslog.h>
        !            71: #include <sys/protosw.h>
        !            72: #include <sys/errno.h>
        !            73: #include <sys/time.h>
        !            74: #include <sys/kernel.h>
        !            75: 
        !            76: #include <net/if.h>
        !            77: 
        !            78: #include <netccitt/hdlc.h>
        !            79: #include <netccitt/hd_var.h>
        !            80: #include <netccitt/x25.h>
        !            81: 
        !            82: /*
        !            83:  *      HDLC OUTPUT INTERFACE
        !            84:  *
        !            85:  *      This routine is called when the X.25 packet layer output routine
        !            86:  *      has a information frame (iframe)  to write.   It is  also called 
        !            87:  *      by the input and control routines of the HDLC layer.
        !            88:  */
        !            89: 
        !            90: hd_output (hdp, m0)
        !            91: register struct hdcb *hdp;
        !            92: struct mbuf *m0;
        !            93: {
        !            94:        struct x25config *xcp;
        !            95:        register struct mbuf *m = m0;
        !            96:        int len;
        !            97: 
        !            98:        if (m == NULL)
        !            99:                panic ("hd_output");
        !           100:        if ((m->m_flags & M_PKTHDR) == 0)
        !           101:                panic ("hd_output 2");
        !           102: 
        !           103:        if (hdp->hd_state != ABM) {
        !           104:                m_freem (m);
        !           105:                return;
        !           106:        }
        !           107: 
        !           108:        /*
        !           109:         * Make room for the hdlc header either by prepending
        !           110:         * another mbuf, or by adjusting the offset and length
        !           111:         * of the first mbuf in the mbuf chain.
        !           112:         */
        !           113: 
        !           114:        M_PREPEND(m, HDHEADERLN, M_DONTWAIT);
        !           115:        if (m == NULL)
        !           116:                return;
        !           117:        for (len = 0; m; m = m->m_next)
        !           118:                len += m->m_len;
        !           119:        m = m0;
        !           120:        m->m_pkthdr.len = len;
        !           121: 
        !           122:        hd_append (&hdp->hd_txq, m);
        !           123:        hd_start (hdp);
        !           124: }
        !           125: 
        !           126: hd_start (hdp)
        !           127: register struct hdcb *hdp;
        !           128: {
        !           129:        register struct mbuf *m;
        !           130: 
        !           131:        /* 
        !           132:         * The iframe is only transmitted if all these conditions are FALSE.
        !           133:         * The iframe remains queued (hdp->hd_txq) however and will be
        !           134:         * transmitted as soon as these conditions are cleared.
        !           135:         */
        !           136: 
        !           137:        while (!(hdp->hd_condition & (TIMER_RECOVERY_CONDITION | REMOTE_RNR_CONDITION | REJ_CONDITION))) {
        !           138:                if (hdp->hd_vs == (hdp->hd_lastrxnr + hdp->hd_xcp->xc_lwsize) % MODULUS) {
        !           139: 
        !           140:                        /* We have now exceeded the  maximum  number  of 
        !           141:                           outstanding iframes. Therefore,  we must wait 
        !           142:                           until  at least  one is acknowledged if this 
        !           143:                           condition  is not  turned off before we are
        !           144:                           requested to write another iframe. */
        !           145:                        hdp->hd_window_condition++;
        !           146:                        break;
        !           147:                }
        !           148: 
        !           149:                /* hd_remove top iframe from transmit queue. */
        !           150:                if ((m = hd_remove (&hdp->hd_txq)) == NULL)
        !           151:                        break;
        !           152: 
        !           153:                hd_send_iframe (hdp, m, POLLOFF);
        !           154:        }
        !           155: }
        !           156: 
        !           157: /* 
        !           158:  *  This procedure is passed a buffer descriptor for an iframe. It builds
        !           159:  *  the rest of the control part of the frame and then writes it out.  It
        !           160:  *  also  starts the  acknowledgement  timer and keeps  the iframe in the
        !           161:  *  Retransmit queue (Retxq) just in case  we have to do this again.
        !           162:  *
        !           163:  *  Note: This routine is also called from hd_input.c when retransmission
        !           164:  *       of old frames is required.
        !           165:  */
        !           166: 
        !           167: hd_send_iframe (hdp, buf, poll_bit)
        !           168: register struct hdcb *hdp;
        !           169: register struct mbuf *buf;
        !           170: int poll_bit;
        !           171: {
        !           172:        register struct Hdlc_iframe *iframe;
        !           173:        struct mbuf *m;
        !           174: 
        !           175:        KILL_TIMER (hdp);
        !           176: 
        !           177:        if (buf == 0) {
        !           178:                printf ("hd_send_iframe: zero arg\n");
        !           179: #ifdef HDLCDEBUG
        !           180:                hd_status (hdp);
        !           181:                hd_dumptrace (hdp);
        !           182: #endif
        !           183:                hdp->hd_vs = (hdp->hd_vs + 7) % MODULUS;
        !           184:                return;
        !           185:        }
        !           186:        iframe = mtod (buf, struct Hdlc_iframe *);
        !           187: 
        !           188:        iframe -> hdlc_0 = 0;
        !           189:        iframe -> nr = hdp->hd_vr;
        !           190:        iframe -> pf = poll_bit;
        !           191:        iframe -> ns = hdp->hd_vs;
        !           192:        iframe -> address = ADDRESS_B;
        !           193:        hdp->hd_lasttxnr = hdp->hd_vr;
        !           194:        hdp->hd_rrtimer = 0;
        !           195: 
        !           196:        if (hdp->hd_vs == hdp->hd_retxqi) {
        !           197:                /* Check for retransmissions. */
        !           198:                /* Put iframe only once in the Retransmission queue. */
        !           199:                hdp->hd_retxq[hdp->hd_retxqi] = buf;
        !           200:                hdp->hd_retxqi = (hdp->hd_retxqi + 1) % MODULUS;
        !           201:                hdp->hd_iframes_out++;
        !           202:        }
        !           203: 
        !           204:        hdp->hd_vs = (hdp->hd_vs + 1) % MODULUS;
        !           205: 
        !           206:        hd_trace (hdp, TX, (struct Hdlc_frame *)iframe);
        !           207: 
        !           208:        /* Write buffer on device. */
        !           209:        m = hdp->hd_dontcopy ? buf : m_copy(buf, 0, (int)M_COPYALL);
        !           210:        if (m == 0) {
        !           211:                printf("hdlc: out of mbufs\n");
        !           212:                return;
        !           213:        }
        !           214:        (*hdp->hd_output)(hdp, m);
        !           215:        SET_TIMER (hdp);
        !           216: }
        !           217: 
        !           218: hd_ifoutput(hdp, m)
        !           219: register struct mbuf *m;
        !           220: register struct hdcb *hdp;
        !           221: {
        !           222:        /*
        !           223:         * Queue message on interface, and start output if interface
        !           224:         * not yet active.
        !           225:         */
        !           226:        register struct ifnet *ifp = hdp->hd_ifp;
        !           227:        int s = splimp();
        !           228: 
        !           229:        if (IF_QFULL(&ifp->if_snd)) {
        !           230:                IF_DROP(&ifp->if_snd);
        !           231:            /* printf("%s%d: HDLC says OK to send but queue full, may hang\n",
        !           232:                        ifp->if_name, ifp->if_unit);*/
        !           233:                m_freem(m);
        !           234:        } else {
        !           235:                IF_ENQUEUE(&ifp->if_snd, m);
        !           236:                if ((ifp->if_flags & IFF_OACTIVE) == 0)
        !           237:                        (*ifp->if_start)(ifp);
        !           238:        }
        !           239:        splx(s);
        !           240: }
        !           241: 
        !           242: 
        !           243: /* 
        !           244:  *  This routine gets control when the timer expires because we have not
        !           245:  *  received an acknowledgement for a iframe.
        !           246:  */
        !           247: 
        !           248: hd_resend_iframe (hdp)
        !           249: register struct hdcb *hdp;
        !           250: {
        !           251: 
        !           252:        if (hdp->hd_retxcnt++ < hd_n2) {
        !           253:                if (!(hdp->hd_condition & TIMER_RECOVERY_CONDITION)) {
        !           254:                        hdp->hd_xx = hdp->hd_vs;
        !           255:                        hdp->hd_condition |= TIMER_RECOVERY_CONDITION;
        !           256:                }
        !           257: 
        !           258:                hdp->hd_vs = hdp->hd_lastrxnr;
        !           259:                hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLON);
        !           260:        } else {
        !           261:                /* At this point we have not received a RR even after N2
        !           262:                   retries - attempt to reset link. */
        !           263: 
        !           264:                hd_initvars (hdp);
        !           265:                hd_writeinternal (hdp, SABM, POLLOFF);
        !           266:                hdp->hd_state = WAIT_UA;
        !           267:                SET_TIMER (hdp);
        !           268:                hd_message (hdp, "Timer recovery failed: link down");
        !           269:                (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
        !           270:        }
        !           271: }

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