101 lines
4 KiB
C++
101 lines
4 KiB
C++
// network.h
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// Data structures to emulate a physical network connection.
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// The network provides the abstraction of ordered, unreliable,
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// fixed-size packet delivery to other machines on the network.
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//
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// You may note that the interface to the network is similar to
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// the console device -- both are full duplex channels.
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//
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// DO NOT CHANGE -- part of the machine emulation
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//
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// Copyright (c) 1992-1993 The Regents of the University of California.
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// All rights reserved. See copyright.h for copyright notice and limitation
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// of liability and disclaimer of warranty provisions.
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#ifndef NETWORK_H
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#define NETWORK_H
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#include "copyright.h"
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#include "utility.h"
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// Network address -- uniquely identifies a machine. This machine's ID
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// is given on the command line.
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typedef int NetworkAddress;
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// The following class defines the network packet header.
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// The packet header is prepended to the data payload by the Network driver,
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// before the packet is sent over the wire. The format on the wire is:
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// packet header (PacketHeader)
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// data (containing MailHeader from the PostOffice!)
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class PacketHeader {
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public:
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NetworkAddress to; // Destination machine ID
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NetworkAddress from; // source machine ID
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unsigned length; // bytes of packet data, excluding the
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// packet header (but including the
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// MailHeader prepended by the post office)
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};
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#define MaxWireSize 64 // largest packet that can go out on the wire
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#define MaxPacketSize (MaxWireSize - sizeof(struct PacketHeader))
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// data "payload" of the largest packet
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// The following class defines a physical network device. The network
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// is capable of delivering fixed sized packets, in order but unreliably,
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// to other machines connected to the network.
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//
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// The "reliability" of the network can be specified to the constructor.
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// This number, between 0 and 1, is the chance that the network will lose
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// a packet. Note that you can change the seed for the random number
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// generator, by changing the arguments to RandomInit() in Initialize().
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// The random number generator is used to choose which packets to drop.
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class Network {
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public:
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Network(NetworkAddress addr, double reliability,
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VoidFunctionPtr readAvailHandler, VoidFunctionPtr writeDoneHandler, void *callArg);
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// Allocate and initialize network driver
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~Network(); // De-allocate the network driver data
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void Send(PacketHeader hdr, const void* data);
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// Send the packet data to a remote machine,
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// specified by "hdr". Returns immediately.
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// "writeHandler" is invoked once the next
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// packet can be sent. Note that writeHandler
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// is called whether or not the packet is
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// dropped, and note that the "from" field of
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// the PacketHeader is filled in automatically
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// by Send().
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PacketHeader Receive(void* data);
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// Poll the network for incoming messages.
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// If there is a packet waiting, copy the
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// packet into "data" and return the header.
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// If no packet is waiting, return a header
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// with length 0.
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void SendDone(); // Interrupt handler, called when message is
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// sent
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void CheckPktAvail(); // Check if there is an incoming packet
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private:
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NetworkAddress ident; // This machine's network address
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double chanceToWork; // Likelihood packet will be dropped
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int sock; // UNIX socket number for incoming packets
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char sockName[32]; // File name corresponding to UNIX socket
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VoidFunctionPtr writeHandler; // Interrupt handler, signalling next packet
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// can be sent.
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VoidFunctionPtr readHandler; // Interrupt handler, signalling packet has
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// arrived.
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void *handlerArg; // Argument to be passed to interrupt handler
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// (pointer to post office)
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bool sendBusy; // Packet is being sent.
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bool packetAvail; // Packet has arrived, can be pulled off of
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// network
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PacketHeader inHdr; // Information about arrived packet
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char inbox[MaxPacketSize]; // Data for arrived packet
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};
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#endif // NETWORK_H
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