-- File: RealForwarder.mesa, Last Edit: HGM March 17, 1981 8:27 PM
DIRECTORY
Process USING [Detach, SetPriority, SetTimeout, MsecToTicks],
Runtime USING [IsBound],
Storage USING [Node],
StatsDefs USING [StatIncr],
CommFlags USING [doStats],
ForwarderDefs USING [
SetupForwarderThings, ForwarderStats, PrintBadPup,
statGateInfoReplies, statRoutingTableChanges, statGateInfoBC,
statGateLowOnBuffers, statGarbageSourceOrDest, statNoRouteToNet,
statTooManyHops, forwarderStatsRequest],
PupRouterDefs USING [
BuildErrorPup, EnumerateRoutingTable, GetRoutingTableEntry, maxHop,
PupGateInfo, PupGatewaySee, RejectPupWithBadChecksum, RoutingTableEntry,
SetBadPupProc, SetPupChecksum],
PupDefs,
DriverDefs USING [Network, GetDeviceChain, MaybeGetFreePupBuffer],
BufferDefs USING [PupBuffer, ReturnFreeBuffer, BuffersLeft, QueueInitialize],
PupTypes USING [
PupNetID, PupHostID, PupErrorCode, allNets, allHosts, gatewaySoc,
maxDataWordsPerRoutingPup];
RealForwarder: MONITOR
IMPORTS
Process, Runtime, Storage, StatsDefs, ForwarderDefs, PupRouterDefs, DriverDefs,
PupDefs, BufferDefs
EXPORTS BufferDefs, ForwarderDefs, PupRouterDefs
SHARES BufferDefs =
BEGIN OPEN StatsDefs, PupRouterDefs, PupDefs, BufferDefs, PupTypes;
-- EXPORTed TYPEs
Network: PUBLIC TYPE = DriverDefs.Network;
tellEverybody: BOOLEAN ← TRUE; -- debugging flag to avoid poluting the world
packets: POINTER TO ARRAY [0..0) OF LONG CARDINAL;
bytes: POINTER TO ARRAY [0..0) OF LONG CARDINAL;
nets: CARDINAL;
stop: BOOLEAN ← FALSE;
pupGateSoc: PupSocket;
GetPointerToPupGateStats: PUBLIC PROCEDURE
RETURNS [
POINTER TO ARRAY [0..0) OF LONG CARDINAL, POINTER TO ARRAY [0..0) OF LONG
CARDINAL, CARDINAL] = BEGIN RETURN[packets, bytes, nets]; END;
PupForwarderOn: PUBLIC PROCEDURE =
BEGIN
network: Network ← DriverDefs.GetDeviceChain[];
IF CommFlags.doStats THEN
BEGIN
finger: Network;
size: CARDINAL;
nets ← 1; -- discard
FOR finger ← network, finger.next UNTIL finger = NIL DO
nets ← nets + 1; ENDLOOP;
size ← nets*nets;
packets ← Storage.Node[2*size];
bytes ← Storage.Node[2*size];
FOR i: CARDINAL IN [0..size) DO packets[i] ← bytes[i] ← 0; ENDLOOP;
END;
Process.Detach[FORK PupForwarderOn2[]];
END;
PupForwarderOn2: ENTRY PROCEDURE =
BEGIN
network: Network ← DriverDefs.GetDeviceChain[];
world: PupAddress ← [[0], [0], gatewaySoc];
spin: CONDITION;
Process.SetTimeout[@spin, Process.MsecToTicks[100]];
-- As a hack, we can run without knowing our network number at startup time.
-- Wait here to be sure we don't polute things if we don't know it yet.
Process.Detach[FORK LookAtBadPups[]];
Process.Detach[FORK TransferForwarderStats[]];
UNTIL network.netNumber # [0, 0] DO IF stop THEN RETURN; WAIT spin; ENDLOOP;
Process.Detach[FORK PupTalk[]];
pupGateSoc ← PupSocketMake[gatewaySoc, world, veryLongWait];
Process.Detach[FORK PupListen[]];
END;
PupForwarderOff: PUBLIC ENTRY PROCEDURE =
BEGIN
spin: CONDITION;
Process.SetTimeout[@spin, Process.MsecToTicks[100]];
stop ← TRUE;
THROUGH [0..5) DO
-- 5 cycles of 100 ms each
NOTIFY talker;
WAIT spin;
ENDLOOP;
END;
PupListen: PUBLIC PROCEDURE =
BEGIN
b: PupBuffer;
DO
b ← pupGateSoc.get[];
IF b = NIL THEN LOOP;
SELECT b.pupType FROM
gatewayRequest =>
BEGIN
IF ~tellEverybody AND b.dest.host = allHosts THEN
BEGIN -- don't answer broadcast requests yet
ReturnFreePupBuffer[b];
END
ELSE
BEGIN
SwapPupSourceAndDest[b];
SendPupRoutingPacket[b];
IF CommFlags.doStats THEN StatIncr[ForwarderDefs.statGateInfoReplies];
END
END;
gatewayInfo =>
BEGIN -- RoutingTable packet from another Gateway
IF PupGatewaySee[b] THEN
BEGIN
KickTalker[];
IF CommFlags.doStats THEN StatIncr[ForwarderDefs.statRoutingTableChanges];
END;
ReturnFreePupBuffer[b];
END;
ForwarderDefs.forwarderStatsRequest => PutStats[b];
ENDCASE => ReturnFreePupBuffer[b];
ENDLOOP;
END;
talker: CONDITION;
KickTalker: PUBLIC ENTRY PROCEDURE = BEGIN NOTIFY talker; END;
PupTalk: PUBLIC ENTRY PROCEDURE =
BEGIN
spin: CONDITION;
b: PupBuffer;
i: CARDINAL ← 0;
Process.SetTimeout[@talker, Process.MsecToTicks[30000]];
Process.SetTimeout[@spin, Process.MsecToTicks[100]];
DO
-- forever
IF tellEverybody THEN
BEGIN
i ← i + 1;
UNTIL (b ← DriverDefs.MaybeGetFreePupBuffer[]) # NIL DO
WAIT spin; ENDLOOP;
b.pupID ← [0, i];
b.dest ← [allNets, allHosts, gatewaySoc];
b.source ← [, , gatewaySoc];
SendPupRoutingPacket[b];
IF CommFlags.doStats THEN StatIncr[ForwarderDefs.statGateInfoBC];
END;
WAIT talker;
ENDLOOP;
END;
SendPupRoutingPacket: PROCEDURE [b: PupBuffer] =
BEGIN
data: LONG POINTER TO PupGateInfo ← LOOPHOLE[@b.pupWords[0]];
AddOne: PROCEDURE [rte: RoutingTableEntry] =
BEGIN
IF rte.net = 0 OR rte.network = NIL THEN RETURN;
IF n = maxDataWordsPerRoutingPup/SIZE[PupGateInfo] THEN
BEGIN
b2: PupBuffer ← DriverDefs.MaybeGetFreePupBuffer[];
IF b2 # NIL THEN
BEGIN
b2.pupID ← b.pupID;
b2.source ← b.source;
b2.dest ← b.dest;
b2.pupType ← b.pupType;
SetPupContentsWords[b, n*SIZE[PupGateInfo]];
PupRouterSendThis[b];
b ← b2;
END;
data ← LOOPHOLE[@b.pupWords[0]];
n ← 0;
END;
IF rte.hop = 0 THEN
data↑ ←
[net: rte.net, viaNet: rte.net, viaHost: [rte.network.hostNumber],
hop: 0]
ELSE
data↑ ←
[net: rte.net, viaNet: [rte.network.netNumber.b], viaHost: rte.route,
hop: rte.hop];
IF stop THEN data.hop ← maxHop + 1;
data ← data + SIZE[PupGateInfo];
n ← n + 1;
END;
n: CARDINAL ← 0;
b.pupType ← gatewayInfo;
EnumerateRoutingTable[AddOne];
SetPupContentsWords[b, n*SIZE[PupGateInfo]];
PupRouterSendThis[b];
END;
magicOne: INTEGER = -9; -- offset for pupTransportControl
magicTwo: CARDINAL = 1;
DoForwardPupBuffer: PUBLIC PROCEDURE [b: PupBuffer] =
BEGIN
fromNetwork: Network ← b.network;
toNetwork: Network;
sourceNet: PupNetID ← b.source.net;
destNet: PupNetID ← b.dest.net;
route: PupHostID;
rte: RoutingTableEntry;
old: WORD;
errorCode: PupTypes.PupErrorCode;
-- Allow directed broadcasts, but avoid nonsense and loops
IF sourceNet = 0 OR destNet = 0 OR b.source.host = allHosts OR
(destNet = fromNetwork.netNumber.b AND b.dest.host = allHosts) THEN
BEGIN -- Don't forward this Pup
ReturnFreePupBuffer[b];
IF CommFlags.doStats THEN StatIncr[statPupNotForwarded];
IF CommFlags.doStats THEN StatIncr[ForwarderDefs.statGarbageSourceOrDest];
RETURN;
END;
old ← (@b.pupWords[0] + magicOne)↑;
IF b.pupTransportControl = maxHop*20B THEN
BEGIN
DoErrorPup[b, eightHopsPupErrorCode, "Discarded by 16th Gateway"];
IF CommFlags.doStats THEN BumpPupStats[fromNetwork.index, 0, 0];
IF CommFlags.doStats THEN StatIncr[ForwarderDefs.statTooManyHops];
RETURN;
END;
b.pupTransportControl ← b.pupTransportControl + 20B;
rte ← GetRoutingTableEntry[destNet];
IF rte = NIL OR rte.hop > maxHop OR (toNetwork ← rte.network) = NIL THEN
BEGIN -- don't know how to get there
DoErrorPup[b, cantGetTherePupErrorCode, "No route to that Net"];
IF CommFlags.doStats THEN BumpPupStats[fromNetwork.index, 0, 0];
IF CommFlags.doStats THEN StatIncr[ForwarderDefs.statNoRouteToNet];
RETURN;
END;
IF BuffersLeft[] < 3 THEN
BEGIN
IF CommFlags.doStats THEN StatIncr[statPupNotForwarded];
ReturnFreeBuffer[b];
IF CommFlags.doStats THEN BumpPupStats[fromNetwork.index, 0, 0];
IF CommFlags.doStats THEN StatIncr[ForwarderDefs.statGateLowOnBuffers];
RETURN;
END;
b.network ← toNetwork;
UpdatePupChecksum[b, magicTwo, old];
IF (route ← rte.route) = 0 THEN route ← b.dest.host;
toNetwork.encapsulatePup[b, route];
errorCode ← toNetwork.forwardBuffer[b];
SELECT errorCode FROM
noErrorPupErrorCode =>
BEGIN
IF CommFlags.doStats THEN
BEGIN
StatIncr[statPupForwarded];
BumpPupStats[fromNetwork.index, toNetwork.index, b.pupLength];
END;
END;
ENDCASE =>
BEGIN
IF errorCode = cantGetTherePupErrorCode AND rte.hop # 0 THEN
rte.hop ← maxHop + 1;
DoErrorPup[b, errorCode, NIL];
IF CommFlags.doStats THEN BumpPupStats[fromNetwork.index, 0, 0];
END;
END;
-- This is the routine that defines the layout of the statistics counters.
-- Note that a dest of 0 is used for discard.
BumpPupStats: PROCEDURE [sourceIndex, destIndex, length: CARDINAL] =
BEGIN
index: CARDINAL = sourceIndex + destIndex*nets;
packets[index] ← packets[index] + 1;
bytes[index] ← bytes[index] + length;
END;
DoErrorPup: PROCEDURE [
b: PupBuffer, code: PupTypes.PupErrorCode, text: STRING] =
BEGIN
destNet: PupNetID;
toNetwork: Network;
route: PupHostID;
rte: RoutingTableEntry;
IF CommFlags.doStats THEN StatIncr[statPupNotForwarded];
IF text = NIL THEN
SELECT code FROM
connectionLimitPupErrorCode =>
BEGIN
text ← "Gateway Output Queue connection limit exceeded";
code ← gatewayResourceLimitsPupErrorCode;
END;
gatewayResourceLimitsPupErrorCode => text ← "Gateway Output Queue full";
cantGetTherePupErrorCode => text ← "No route to host";
ENDCASE;
IF ~PupRouterDefs.BuildErrorPup[b, code, text] THEN RETURN;
destNet ← b.dest.net;
b.source.socket ← [0, 0];
rte ← GetRoutingTableEntry[destNet];
IF rte = NIL OR rte.hop > maxHop OR (toNetwork ← rte.network) = NIL THEN
BEGIN ReturnFreePupBuffer[b]; RETURN; END;
b.network ← toNetwork;
IF (route ← rte.route) = 0 THEN route ← b.dest.host;
SetPupChecksum[b];
toNetwork.encapsulatePup[b, route];
toNetwork.sendBuffer[b];
END;
UpdatePupChecksum: PUBLIC PROCEDURE [
b: PupBuffer, offset: INTEGER, oldValue: WORD] =
BEGIN
len: CARDINAL ← (b.pupLength - 1)/2;
checksumLoc: LONG POINTER ← @b.pupLength + len;
diff: WORD;
IF checksumLoc↑ = 177777B THEN RETURN;
diff ← OnesSub[b.pupWords[offset + (magicOne - magicTwo)], oldValue];
checksumLoc↑ ← OnesAdd[checksumLoc↑, LeftCycle[diff, len - offset]];
END;
OnesAdd: PROCEDURE [a, b: CARDINAL] RETURNS [c: CARDINAL] = INLINE
BEGIN c ← a + b; IF c < a THEN c ← c + 1; IF c = 177777B THEN c ← 0; END;
OnesSub: PROCEDURE [a, b: CARDINAL] RETURNS [c: CARDINAL] = INLINE
BEGIN
c ← a + (-b - 1);
IF c < a THEN c ← c + 1;
IF c = 177777B THEN c ← 0;
END;
LeftCycle: PROCEDURE [a, b: CARDINAL] RETURNS [c: CARDINAL] = INLINE
BEGIN
c ← a;
THROUGH [0..(b MOD 16)) DO
IF c < 100000B THEN c ← c*2 ELSE c ← c*2 + 1; ENDLOOP;
END;
badPupArrived: CONDITION;
badPupQueue: QueueObject;
PutBadPup: ENTRY PROCEDURE [b: PupBuffer] =
BEGIN
IF badPupQueue.length > 5 THEN
BEGIN PupRouterDefs.RejectPupWithBadChecksum[b]; RETURN; END;
EnqueuePup[@badPupQueue, b];
NOTIFY badPupArrived;
END;
GetBadPup: ENTRY PROCEDURE RETURNS [b: PupBuffer] =
BEGIN
IF badPupQueue.length = 0 THEN WAIT badPupArrived;
b ← DequeuePup[@badPupQueue];
END;
LookAtBadPups: PROCEDURE =
BEGIN
IF ~Runtime.IsBound[ForwarderDefs.PrintBadPup] THEN RETURN;
Process.SetPriority[1];
PupRouterDefs.SetBadPupProc[PutBadPup];
DO ForwarderDefs.PrintBadPup[GetBadPup[]]; ENDLOOP;
END;
-- UGH, we can't just call somebody because we don't want to clutter up core with stuff that isn't normally needed, so we go through this horrible process switch to change priorities.
statsArrived: CONDITION;
statsQueue: QueueObject;
PutStats: ENTRY PROCEDURE [b: PupBuffer] =
BEGIN
IF statsQueue.length > 5 THEN BEGIN ReturnFreePupBuffer[b]; RETURN; END;
EnqueuePup[@statsQueue, b];
NOTIFY statsArrived;
END;
GetStats: ENTRY PROCEDURE RETURNS [b: PupBuffer] =
BEGIN
WHILE statsQueue.length = 0 DO WAIT statsArrived; ENDLOOP;
b ← DequeuePup[@statsQueue];
END;
TransferForwarderStats: PROCEDURE =
BEGIN
Process.SetPriority[1];
DO ForwarderDefs.ForwarderStats[GetStats[]]; ENDLOOP;
END;
-- Initialization
ForwarderDefs.SetupForwarderThings[];
BufferDefs.QueueInitialize[@badPupQueue];
Process.SetTimeout[@badPupArrived, Process.MsecToTicks[60000]];
BufferDefs.QueueInitialize[@statsQueue];
Process.SetTimeout[@statsArrived, Process.MsecToTicks[60000]];
END.