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Annotation of Net2/netccitt/hd_output.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) University of British Columbia, 1984
        !             3:  * Copyright (c) 1990 The Regents of the University of California.
        !             4:  * All rights reserved.
        !             5:  *
        !             6:  * This code is derived from software contributed to Berkeley by
        !             7:  * the Laboratory for Computation Vision and the Computer Science Department
        !             8:  * of the University of British Columbia.
        !             9:  *
        !            10:  * Redistribution and use in source and binary forms, with or without
        !            11:  * modification, are permitted provided that the following conditions
        !            12:  * are met:
        !            13:  * 1. Redistributions of source code must retain the above copyright
        !            14:  *    notice, this list of conditions and the following disclaimer.
        !            15:  * 2. Redistributions in binary form must reproduce the above copyright
        !            16:  *    notice, this list of conditions and the following disclaimer in the
        !            17:  *    documentation and/or other materials provided with the distribution.
        !            18:  * 3. All advertising materials mentioning features or use of this software
        !            19:  *    must display the following acknowledgement:
        !            20:  *     This product includes software developed by the University of
        !            21:  *     California, Berkeley and its contributors.
        !            22:  * 4. Neither the name of the University nor the names of its contributors
        !            23:  *    may be used to endorse or promote products derived from this software
        !            24:  *    without specific prior written permission.
        !            25:  *
        !            26:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            27:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            28:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            29:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            30:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            31:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            32:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            33:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            34:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            35:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            36:  * SUCH DAMAGE.
        !            37:  *
        !            38:  *     @(#)hd_output.c 7.6 (Berkeley) 5/29/91
        !            39:  */
        !            40: 
        !            41: #include "param.h"
        !            42: #include "systm.h"
        !            43: #include "mbuf.h"
        !            44: #include "domain.h"
        !            45: #include "socket.h"
        !            46: #include "syslog.h"
        !            47: #include "protosw.h"
        !            48: #include "errno.h"
        !            49: #include "time.h"
        !            50: #include "kernel.h"
        !            51: 
        !            52: #include "../net/if.h"
        !            53: 
        !            54: #include "hdlc.h"
        !            55: #include "hd_var.h"
        !            56: #include "x25.h"
        !            57: 
        !            58: /*
        !            59:  *      HDLC OUTPUT INTERFACE
        !            60:  *
        !            61:  *      This routine is called when the X.25 packet layer output routine
        !            62:  *      has a information frame (iframe)  to write.   It is  also called 
        !            63:  *      by the input and control routines of the HDLC layer.
        !            64:  */
        !            65: 
        !            66: hd_output (hdp, m0)
        !            67: register struct hdcb *hdp;
        !            68: struct mbuf *m0;
        !            69: {
        !            70:        struct x25config *xcp;
        !            71:        register struct mbuf *m = m0;
        !            72:        int len;
        !            73: 
        !            74:        if (m == NULL)
        !            75:                panic ("hd_output");
        !            76:        if (m->m_flags & M_PKTHDR == 0)
        !            77:                panic ("hd_output 2");
        !            78: 
        !            79:        if (hdp->hd_state != ABM) {
        !            80:                m_freem (m);
        !            81:                return;
        !            82:        }
        !            83: 
        !            84:        /*
        !            85:         * Make room for the hdlc header either by prepending
        !            86:         * another mbuf, or by adjusting the offset and length
        !            87:         * of the first mbuf in the mbuf chain.
        !            88:         */
        !            89: 
        !            90:        M_PREPEND(m, HDHEADERLN, M_DONTWAIT);
        !            91:        if (m == NULL)
        !            92:                return;
        !            93:        for (len = 0; m; m = m->m_next)
        !            94:                len += m->m_len;
        !            95:        m = m0;
        !            96:        m->m_pkthdr.len = len;
        !            97: 
        !            98:        hd_append (&hdp->hd_txq, m);
        !            99:        hd_start (hdp);
        !           100: }
        !           101: 
        !           102: hd_start (hdp)
        !           103: register struct hdcb *hdp;
        !           104: {
        !           105:        register struct mbuf *m;
        !           106: 
        !           107:        /* 
        !           108:         * The iframe is only transmitted if all these conditions are FALSE.
        !           109:         * The iframe remains queued (hdp->hd_txq) however and will be
        !           110:         * transmitted as soon as these conditions are cleared.
        !           111:         */
        !           112: 
        !           113:        while (!(hdp->hd_condition & (TIMER_RECOVERY_CONDITION | REMOTE_RNR_CONDITION | REJ_CONDITION))) {
        !           114:                if (hdp->hd_vs == (hdp->hd_lastrxnr + hdp->hd_xcp->xc_lwsize) % MODULUS) {
        !           115: 
        !           116:                        /* We have now exceeded the  maximum  number  of 
        !           117:                           outstanding iframes. Therefore,  we must wait 
        !           118:                           until  at least  one is acknowledged if this 
        !           119:                           condition  is not  turned off before we are
        !           120:                           requested to write another iframe. */
        !           121:                        hdp->hd_window_condition++;
        !           122:                        break;
        !           123:                }
        !           124: 
        !           125:                /* hd_remove top iframe from transmit queue. */
        !           126:                if ((m = hd_remove (&hdp->hd_txq)) == NULL)
        !           127:                        break;
        !           128: 
        !           129:                hd_send_iframe (hdp, m, POLLOFF);
        !           130:        }
        !           131: }
        !           132: 
        !           133: /* 
        !           134:  *  This procedure is passed a buffer descriptor for an iframe. It builds
        !           135:  *  the rest of the control part of the frame and then writes it out.  It
        !           136:  *  also  starts the  acknowledgement  timer and keeps  the iframe in the
        !           137:  *  Retransmit queue (Retxq) just in case  we have to do this again.
        !           138:  *
        !           139:  *  Note: This routine is also called from hd_input.c when retransmission
        !           140:  *       of old frames is required.
        !           141:  */
        !           142: 
        !           143: hd_send_iframe (hdp, buf, poll_bit)
        !           144: register struct hdcb *hdp;
        !           145: register struct mbuf *buf;
        !           146: int poll_bit;
        !           147: {
        !           148:        register struct Hdlc_iframe *iframe;
        !           149:        struct mbuf *m;
        !           150: 
        !           151:        KILL_TIMER (hdp);
        !           152: 
        !           153:        if (buf == 0) {
        !           154:                printf ("hd_send_iframe: zero arg\n");
        !           155: #ifdef HDLCDEBUG
        !           156:                hd_status (hdp);
        !           157:                hd_dumptrace (hdp);
        !           158: #endif
        !           159:                hdp->hd_vs = (hdp->hd_vs + 7) % MODULUS;
        !           160:                return;
        !           161:        }
        !           162:        iframe = mtod (buf, struct Hdlc_iframe *);
        !           163: 
        !           164:        iframe -> hdlc_0 = 0;
        !           165:        iframe -> nr = hdp->hd_vr;
        !           166:        iframe -> pf = poll_bit;
        !           167:        iframe -> ns = hdp->hd_vs;
        !           168:        iframe -> address = ADDRESS_B;
        !           169:        hdp->hd_lasttxnr = hdp->hd_vr;
        !           170:        hdp->hd_rrtimer = 0;
        !           171: 
        !           172:        if (hdp->hd_vs == hdp->hd_retxqi) {
        !           173:                /* Check for retransmissions. */
        !           174:                /* Put iframe only once in the Retransmission queue. */
        !           175:                hdp->hd_retxq[hdp->hd_retxqi] = buf;
        !           176:                hdp->hd_retxqi = (hdp->hd_retxqi + 1) % MODULUS;
        !           177:                hdp->hd_iframes_out++;
        !           178:        }
        !           179: 
        !           180:        hdp->hd_vs = (hdp->hd_vs + 1) % MODULUS;
        !           181: 
        !           182:        hd_trace (hdp, TX, (struct Hdlc_frame *)iframe);
        !           183: 
        !           184:        /* Write buffer on device. */
        !           185:        m = hdp->hd_dontcopy ? buf : m_copy(buf, 0, (int)M_COPYALL);
        !           186:        if (m == 0) {
        !           187:                printf("hdlc: out of mbufs\n");
        !           188:                return;
        !           189:        }
        !           190:        (*hdp->hd_output)(hdp, m);
        !           191:        SET_TIMER (hdp);
        !           192: }
        !           193: 
        !           194: hd_ifoutput(hdp, m)
        !           195: register struct mbuf *m;
        !           196: register struct hdcb *hdp;
        !           197: {
        !           198:        /*
        !           199:         * Queue message on interface, and start output if interface
        !           200:         * not yet active.
        !           201:         */
        !           202:        register struct ifnet *ifp = hdp->hd_ifp;
        !           203:        int s = splimp();
        !           204: 
        !           205:        if (IF_QFULL(&ifp->if_snd)) {
        !           206:                IF_DROP(&ifp->if_snd);
        !           207:            /* printf("%s%d: HDLC says OK to send but queue full, may hang\n",
        !           208:                        ifp->if_name, ifp->if_unit);*/
        !           209:                m_freem(m);
        !           210:        } else {
        !           211:                IF_ENQUEUE(&ifp->if_snd, m);
        !           212:                if ((ifp->if_flags & IFF_OACTIVE) == 0)
        !           213:                        (*ifp->if_start)(ifp);
        !           214:        }
        !           215:        splx(s);
        !           216: }
        !           217: 
        !           218: 
        !           219: /* 
        !           220:  *  This routine gets control when the timer expires because we have not
        !           221:  *  received an acknowledgement for a iframe.
        !           222:  */
        !           223: 
        !           224: hd_resend_iframe (hdp)
        !           225: register struct hdcb *hdp;
        !           226: {
        !           227: 
        !           228:        if (hdp->hd_retxcnt++ < hd_n2) {
        !           229:                if (!(hdp->hd_condition & TIMER_RECOVERY_CONDITION)) {
        !           230:                        hdp->hd_xx = hdp->hd_vs;
        !           231:                        hdp->hd_condition |= TIMER_RECOVERY_CONDITION;
        !           232:                }
        !           233: 
        !           234:                hdp->hd_vs = hdp->hd_lastrxnr;
        !           235:                hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLON);
        !           236:        } else {
        !           237:                /* At this point we have not received a RR even after N2
        !           238:                   retries - attempt to reset link. */
        !           239: 
        !           240:                hd_initvars (hdp);
        !           241:                hd_writeinternal (hdp, SABM, POLLOFF);
        !           242:                hdp->hd_state = WAIT_UA;
        !           243:                SET_TIMER (hdp);
        !           244:                hd_message (hdp, "Timer recovery failed: link down");
        !           245:                (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
        !           246:        }
        !           247: }

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