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

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*
        !            23:  * Copyright (c) University of British Columbia, 1984
        !            24:  * Copyright (c) 1990, 1993
        !            25:  *     The Regents of the University of California.  All rights reserved.
        !            26:  *
        !            27:  * This code is derived from software contributed to Berkeley by
        !            28:  * the Laboratory for Computation Vision and the Computer Science Department
        !            29:  * of the University of British Columbia.
        !            30:  *
        !            31:  * Redistribution and use in source and binary forms, with or without
        !            32:  * modification, are permitted provided that the following conditions
        !            33:  * are met:
        !            34:  * 1. Redistributions of source code must retain the above copyright
        !            35:  *    notice, this list of conditions and the following disclaimer.
        !            36:  * 2. Redistributions in binary form must reproduce the above copyright
        !            37:  *    notice, this list of conditions and the following disclaimer in the
        !            38:  *    documentation and/or other materials provided with the distribution.
        !            39:  * 3. All advertising materials mentioning features or use of this software
        !            40:  *    must display the following acknowledgement:
        !            41:  *     This product includes software developed by the University of
        !            42:  *     California, Berkeley and its contributors.
        !            43:  * 4. Neither the name of the University nor the names of its contributors
        !            44:  *    may be used to endorse or promote products derived from this software
        !            45:  *    without specific prior written permission.
        !            46:  *
        !            47:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            48:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            49:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            50:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            51:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            52:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            53:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            54:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            55:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            56:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            57:  * SUCH DAMAGE.
        !            58:  *
        !            59:  *     @(#)hd_output.c 8.1 (Berkeley) 6/10/93
        !            60:  */
        !            61: 
        !            62: #include <sys/param.h>
        !            63: #include <sys/systm.h>
        !            64: #include <sys/mbuf.h>
        !            65: #include <sys/domain.h>
        !            66: #include <sys/socket.h>
        !            67: #include <sys/syslog.h>
        !            68: #include <sys/protosw.h>
        !            69: #include <sys/errno.h>
        !            70: #include <sys/time.h>
        !            71: #include <sys/kernel.h>
        !            72: 
        !            73: #include <net/if.h>
        !            74: 
        !            75: #include <netccitt/hdlc.h>
        !            76: #include <netccitt/hd_var.h>
        !            77: #include <netccitt/x25.h>
        !            78: 
        !            79: /*
        !            80:  *      HDLC OUTPUT INTERFACE
        !            81:  *
        !            82:  *      This routine is called when the X.25 packet layer output routine
        !            83:  *      has a information frame (iframe)  to write.   It is  also called 
        !            84:  *      by the input and control routines of the HDLC layer.
        !            85:  */
        !            86: 
        !            87: hd_output (hdp, m0)
        !            88: register struct hdcb *hdp;
        !            89: struct mbuf *m0;
        !            90: {
        !            91:        struct x25config *xcp;
        !            92:        register struct mbuf *m = m0;
        !            93:        int len;
        !            94: 
        !            95:        if (m == NULL)
        !            96:                panic ("hd_output");
        !            97:        if ((m->m_flags & M_PKTHDR) == 0)
        !            98:                panic ("hd_output 2");
        !            99: 
        !           100:        if (hdp->hd_state != ABM) {
        !           101:                m_freem (m);
        !           102:                return;
        !           103:        }
        !           104: 
        !           105:        /*
        !           106:         * Make room for the hdlc header either by prepending
        !           107:         * another mbuf, or by adjusting the offset and length
        !           108:         * of the first mbuf in the mbuf chain.
        !           109:         */
        !           110: 
        !           111:        M_PREPEND(m, HDHEADERLN, M_DONTWAIT);
        !           112:        if (m == NULL)
        !           113:                return;
        !           114:        for (len = 0; m; m = m->m_next)
        !           115:                len += m->m_len;
        !           116:        m = m0;
        !           117:        m->m_pkthdr.len = len;
        !           118: 
        !           119:        hd_append (&hdp->hd_txq, m);
        !           120:        hd_start (hdp);
        !           121: }
        !           122: 
        !           123: hd_start (hdp)
        !           124: register struct hdcb *hdp;
        !           125: {
        !           126:        register struct mbuf *m;
        !           127: 
        !           128:        /* 
        !           129:         * The iframe is only transmitted if all these conditions are FALSE.
        !           130:         * The iframe remains queued (hdp->hd_txq) however and will be
        !           131:         * transmitted as soon as these conditions are cleared.
        !           132:         */
        !           133: 
        !           134:        while (!(hdp->hd_condition & (TIMER_RECOVERY_CONDITION | REMOTE_RNR_CONDITION | REJ_CONDITION))) {
        !           135:                if (hdp->hd_vs == (hdp->hd_lastrxnr + hdp->hd_xcp->xc_lwsize) % MODULUS) {
        !           136: 
        !           137:                        /* We have now exceeded the  maximum  number  of 
        !           138:                           outstanding iframes. Therefore,  we must wait 
        !           139:                           until  at least  one is acknowledged if this 
        !           140:                           condition  is not  turned off before we are
        !           141:                           requested to write another iframe. */
        !           142:                        hdp->hd_window_condition++;
        !           143:                        break;
        !           144:                }
        !           145: 
        !           146:                /* hd_remove top iframe from transmit queue. */
        !           147:                if ((m = hd_remove (&hdp->hd_txq)) == NULL)
        !           148:                        break;
        !           149: 
        !           150:                hd_send_iframe (hdp, m, POLLOFF);
        !           151:        }
        !           152: }
        !           153: 
        !           154: /* 
        !           155:  *  This procedure is passed a buffer descriptor for an iframe. It builds
        !           156:  *  the rest of the control part of the frame and then writes it out.  It
        !           157:  *  also  starts the  acknowledgement  timer and keeps  the iframe in the
        !           158:  *  Retransmit queue (Retxq) just in case  we have to do this again.
        !           159:  *
        !           160:  *  Note: This routine is also called from hd_input.c when retransmission
        !           161:  *       of old frames is required.
        !           162:  */
        !           163: 
        !           164: hd_send_iframe (hdp, buf, poll_bit)
        !           165: register struct hdcb *hdp;
        !           166: register struct mbuf *buf;
        !           167: int poll_bit;
        !           168: {
        !           169:        register struct Hdlc_iframe *iframe;
        !           170:        struct mbuf *m;
        !           171: 
        !           172:        KILL_TIMER (hdp);
        !           173: 
        !           174:        if (buf == 0) {
        !           175:                printf ("hd_send_iframe: zero arg\n");
        !           176: #ifdef HDLCDEBUG
        !           177:                hd_status (hdp);
        !           178:                hd_dumptrace (hdp);
        !           179: #endif
        !           180:                hdp->hd_vs = (hdp->hd_vs + 7) % MODULUS;
        !           181:                return;
        !           182:        }
        !           183:        iframe = mtod (buf, struct Hdlc_iframe *);
        !           184: 
        !           185:        iframe -> hdlc_0 = 0;
        !           186:        iframe -> nr = hdp->hd_vr;
        !           187:        iframe -> pf = poll_bit;
        !           188:        iframe -> ns = hdp->hd_vs;
        !           189:        iframe -> address = ADDRESS_B;
        !           190:        hdp->hd_lasttxnr = hdp->hd_vr;
        !           191:        hdp->hd_rrtimer = 0;
        !           192: 
        !           193:        if (hdp->hd_vs == hdp->hd_retxqi) {
        !           194:                /* Check for retransmissions. */
        !           195:                /* Put iframe only once in the Retransmission queue. */
        !           196:                hdp->hd_retxq[hdp->hd_retxqi] = buf;
        !           197:                hdp->hd_retxqi = (hdp->hd_retxqi + 1) % MODULUS;
        !           198:                hdp->hd_iframes_out++;
        !           199:        }
        !           200: 
        !           201:        hdp->hd_vs = (hdp->hd_vs + 1) % MODULUS;
        !           202: 
        !           203:        hd_trace (hdp, TX, (struct Hdlc_frame *)iframe);
        !           204: 
        !           205:        /* Write buffer on device. */
        !           206:        m = hdp->hd_dontcopy ? buf : m_copy(buf, 0, (int)M_COPYALL);
        !           207:        if (m == 0) {
        !           208:                printf("hdlc: out of mbufs\n");
        !           209:                return;
        !           210:        }
        !           211:        (*hdp->hd_output)(hdp, m);
        !           212:        SET_TIMER (hdp);
        !           213: }
        !           214: 
        !           215: hd_ifoutput(hdp, m)
        !           216: register struct mbuf *m;
        !           217: register struct hdcb *hdp;
        !           218: {
        !           219:        /*
        !           220:         * Queue message on interface, and start output if interface
        !           221:         * not yet active.
        !           222:         */
        !           223:        register struct ifnet *ifp = hdp->hd_ifp;
        !           224:        int s = splimp();
        !           225: 
        !           226:        if (IF_QFULL(&ifp->if_snd)) {
        !           227:                IF_DROP(&ifp->if_snd);
        !           228:            /* printf("%s%d: HDLC says OK to send but queue full, may hang\n",
        !           229:                        ifp->if_name, ifp->if_unit);*/
        !           230:                m_freem(m);
        !           231:        } else {
        !           232:                IF_ENQUEUE(&ifp->if_snd, m);
        !           233:                if ((ifp->if_flags & IFF_OACTIVE) == 0)
        !           234:                        (*ifp->if_start)(ifp);
        !           235:        }
        !           236:        splx(s);
        !           237: }
        !           238: 
        !           239: 
        !           240: /* 
        !           241:  *  This routine gets control when the timer expires because we have not
        !           242:  *  received an acknowledgement for a iframe.
        !           243:  */
        !           244: 
        !           245: hd_resend_iframe (hdp)
        !           246: register struct hdcb *hdp;
        !           247: {
        !           248: 
        !           249:        if (hdp->hd_retxcnt++ < hd_n2) {
        !           250:                if (!(hdp->hd_condition & TIMER_RECOVERY_CONDITION)) {
        !           251:                        hdp->hd_xx = hdp->hd_vs;
        !           252:                        hdp->hd_condition |= TIMER_RECOVERY_CONDITION;
        !           253:                }
        !           254: 
        !           255:                hdp->hd_vs = hdp->hd_lastrxnr;
        !           256:                hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLON);
        !           257:        } else {
        !           258:                /* At this point we have not received a RR even after N2
        !           259:                   retries - attempt to reset link. */
        !           260: 
        !           261:                hd_initvars (hdp);
        !           262:                hd_writeinternal (hdp, SABM, POLLOFF);
        !           263:                hdp->hd_state = WAIT_UA;
        !           264:                SET_TIMER (hdp);
        !           265:                hd_message (hdp, "Timer recovery failed: link down");
        !           266:                (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
        !           267:        }
        !           268: }

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