
    <<ArpaICMPBuf.mesa>>
        <<Copyright © 1986 by Xerox Corporation.  All rights reserved.>>
        <<Demers, July 24, 1987 9:28:07 pm PDT>>
    <<>>
    <<Format for Arpa ICMP packets.>>
    <<>>
    DIRECTORY
        ArpaBuf USING[Hdr, maxBodyBytes],
        Basics USING [FWORD, HWORD],
        CommBuffer USING [Overhead];

    ArpaICMPBuf: CEDAR DEFINITIONS ~ {

        HWORD: TYPE ~ Basics.HWORD;
        FWORD: TYPE ~ Basics.FWORD;

        maxBytes: CARDINAL ~ ArpaBuf.maxBodyBytes;

    <<Header>>
    ICMPType: TYPE ~ MACHINE DEPENDENT {
    echoReply(0),
    destUnreachable(3),
    sourceQuench(4),
    redirect(5),
    echo(8),
    timeExceeded(11),
    parameterProblem(12),
    timestamp(13),
    timestampReply(14),
    infoRequest(15),
    infoReply(16),
    last(0FFH)
    };

    ICMPCode: TYPE ~ BYTE;
    <<Must be 0 except for the type-specific codes defined below ...>>

    DestUnreachableCode: TYPE ~ MACHINE DEPENDENT {
    netUnreachable(0),
    hostUnreachable(1),
    protocolUnreachable(2),
    portUnreachable(3),
    mustFragment(4),
    sourceRouteFailure(5),
    last(0FFH)
    };

    RedirectCode: TYPE ~ MACHINE DEPENDENT {
    network(0),
    host(1),
    networkAndService(2),
    hostAndService(3),
    last(0FFH)
    };

    TimeExceededCode: TYPE ~ MACHINE DEPENDENT {
    timeToLive(0),
    fragmentReassembly(1),
    last(0FFH)
    };

        Hdr: TYPE ~ MACHINE DEPENDENT RECORD [
            SELECT OVERLAID * FROM
                any => [icmpType: ICMPType,
                icmpCode: ICMPCode,
                checksum: HWORD],
                destUnreachable => [destUnreachableType: ICMPType,
                destUnreachableCode: DestUnreachableCode],
                redirect => [redirectType: ICMPType,
                redirectCode: RedirectCode],
                timeExceeded => [timeExceededType: ICMPType,
                timeExceededCode: TimeExceededCode],
                ENDCASE
            ];

        hdrBytes: CARDINAL ~ BYTES[Hdr];

    <<Body>>
        Body: TYPE ~ MACHINE DEPENDENT RECORD [
            SELECT OVERLAID * FROM
                bytes => [bytes: PACKED ARRAY [0..maxBodyBytes) OF BYTE],
                chars => [chars: PACKED ARRAY [0..maxBodyChars) OF CHAR],
                hWords => [hWords: PACKED ARRAY [0..maxBodyHWords) OF HWORD],
                fWords => [fWords: PACKED ARRAY [0..maxBodyFWords) OF FWORD],

                echoReply => [echoReply: EchoRequestOrReplyBody],
                destUnreachable => [destUnreachable: ReturnedDataBody],
                sourceQuench => [sourceQuench: ReturnedDataBody],
                redirect => [redirect: ReturnedDataAndAddressBody],
                echo => [echoReply: EchoRequestOrReplyBody],
                timeExceeded => [timeExceeded: ReturnedDataBody],
                parameterProblem => [parameterProblem: ReturnedDataAndPointerBody],
                timestamp => [timestamp: TimesBody],
                timestampReply => [timestampReply: TimesBody],
                infoRequest => [infoRequest: InfoRequestOrReplyBody],
                infoReply => [infoReply: InfoRequestOrReplyBody]
                ENDCASE
            ];

        maxBodyBytes: CARDINAL ~ maxBytes - hdrBytes;
        maxBodyChars: CARDINAL ~ maxBodyBytes;
        maxBodyHWords: CARDINAL ~ maxBodyBytes/BYTES[HWORD];
        maxBodyFWords: CARDINAL ~ maxBodyBytes/BYTES[FWORD];


        EchoRequestOrReplyBody: TYPE ~ MACHINE DEPENDENT RECORD [
            identifier: HWORD,
        sequenceNum: HWORD,
            data: PACKED ARRAY [0..maxEchoBodyBytes) OF BYTE
            ];

        maxEchoBodyBytes: CARDINAL ~ maxBytes - hdrBytes - 2*BYTES[HWORD];

        ReturnedDataBody: TYPE ~ MACHINE DEPENDENT RECORD [
            unused: FWORD,
            origHdr: ArpaBuf.Hdr,
            origBody: PACKED ARRAY [0..8) OF BYTE
            ];

        ReturnedDataAndAddressBody: TYPE ~ MACHINE DEPENDENT RECORD [
            unused: FWORD,
            origHdr: ArpaBuf.Hdr,
            origBody: PACKED ARRAY [0..8) OF BYTE
            ];

        ReturnedDataAndPointerBody: TYPE ~ MACHINE DEPENDENT RECORD [
            pointer: BYTE,
            unused1, unused2, unused3: BYTE,
            origHdr: ArpaBuf.Hdr,
            origBody: PACKED ARRAY [0..8) OF BYTE
            ];

        TimesBody: TYPE ~ MACHINE DEPENDENT RECORD [
            identifier: HWORD,
            sequenceNum: HWORD,
            originateTimestamp: Timestamp,
            receiveTimestamp: Timestamp,
            transmitTimestamp: Timestamp
            ];

        Timestamp: TYPE ~ FWORD; -- milliseconds since midnight UT.

        InfoRequestOrReplyBody: TYPE ~ MACHINE DEPENDENT RECORD [
            identifier: HWORD,
            sequenceNum: HWORD
            ];
    <<Packet>>
        Packet: TYPE ~ REF PacketObject;
        PacketObject: TYPE ~ MACHINE DEPENDENT RECORD [
            hdr: Hdr,
            body: Body];

    <<Buffer>>
        <<All buffers start out as Driver.Buffer's.  Clients may SmashType between Driver.Buffer and ArpaBuf.Buffer, so the "right" module 
        gets to do finalization.  This is VERY delicate.>>
        <<>>
        Buffer: TYPE ~ REF BufferObject;
        BufferObject: TYPE ~ MACHINE DEPENDENT RECORD [
            ovh: CommBuffer.Overhead,
            hdr1: ArpaBuf.Hdr,
            hdr2: Hdr,
            body: Body];
        <<>>
        }.