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TOPS-20_V6.1_DECnetSrc_7-23-85
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mcb/xpt/xptdec.bli
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module XPTDEC (
IDENT = 'X01390'
) =
begin
!
! COPYRIGHT (c) 1980, 1981, 1982
! DIGITAL EQUIPMENT CORPORATION
! Maynard, Massachusetts
!
! This software is furnished under a license and may be used
! and copied only in accordance with the terms of such license
! and with the inclusion of the above copyright notice. This
! software or any other copies thereof may not be provided or
! otherwise made available to any other person. No title to
! and ownership of the software is hereby transferred.
!
! The information in this software is subject to change
! without notice and should not be construed as a commitment
! by DIGITAL EQUIPMENT CORPORATION.
!
! DIGITAL assumes no responsibility for the use or reliability
! of its software on equipment which is not supplied by
! DIGITAL.
!
!++
! FACILITY: DECnet Transport
!
! ABSTRACT:
!
! Transport Decision process. Maintains transport routing data bases
! and selects routing paths.
!
! ENVIRONMENT: MCB
!
! AUTHOR: L. Webber , CREATION DATE: 16-Jul-79
!
! MODIFIED BY:
!
! L. Webber, 16-Jul-79 : VERSION 1.00
!
! 1.01 L. Webber, 20-Dec-79
! Modifications associated with splitting Transport Line Interface out
!
! 1.02 L. Webber, 24-Jan-80
! Put Hop and Cost in a single matrix; modified algorithms as per
! 22-Jan-80 architecture change
!
! 1.03 L. Webber, 29-Jan-80
! Modify interfaces to OPENT and CLOSET to match standard dispatch
! linkage.
!
! 1.04 L. Webber, 2-Apr-80
! Modify to support node and line sub-data-bases
!
! 1.05 L. Webber, 30-Jun-80
! Modify to use MCBLIB macros
!
! 1.06 A. Peckham, 15-Oct-80
! Update for new function modifiers.
!
! 1.07 A. Peckham, 21-Oct-80
! Change CE_ERR return code to SIGNAL_STOP.
!
! 1.08 L. Webber, 11-Dec-80
! Modify to support MCB 3.1
!
! 1.09 L. Webber, 20-Jan-81
! Change definition of MATRIX structure to take NLN as an actual.
!
! 1.10 L. Webber, 26-Jan-81
! Add Event Logging and Counter Incrementing
!
! 1.11 L. Webber, 10-Feb-81
! MAPBUF is now a macro
!
! 1.12 L. Webber, 23-Feb-81
! Add event logging for reachability changes and line up;
! make Event Buffer image field
!
! 1.13 L. Webber, 1-Apr-81
! Fix length of event buffer reason code in VALID_BUFFER.
!
! 1.14 L. Webber, 3-Apr-81
! Transform all reason code insertions into calls to EP_REASON.
! Add call to EP_EXNODE (expected node).
!
! 1.15 L. Webber, 3-Apr-81
! Put in LIX as entity ID for all events (except for node reachability
! change, which takes node address).
!
! 1.16 L. Webber, 14-Apr-81
! Call $XPECLN when a node becomes unreachable, to clean out the
! Link Translate Table of all links to/from the node.
!
! 1.17 L. Webber, 10-May-81
! Add code to call do an $MCB_PAUSE every once in a while during the
! routing algorithm.
!
! 1.18 L. Webber, 15-May-81
! Do an $MCB_PAUSE every time there's something on the synch queue.
! Make IncN the number of pauses this time through the algorithm.
!
! 1.19 L. Webber, 1-Jun-81
! Modify all LOG_EVENT calls for a circuit entity to pass the NMXid.
!
! 1.20 L. Webber, 6-Jul-81
! Fix VALID_BUFFER not to ignore routing messages with reachable nodes
! past NN. Also, modify the event logging of that event to give the
! highest reachable node in the message instead of the local NN.
!
! 1.21 L. Webber, 13-Jul-81
! Modify linkage to COSTCH.
!
! 1.22 L. Webber, 13-Jul-81
! Fix 1.21 so that COSTCH doesn't call ROUTES (TLI is the wrong process
! context). Instead, it will cause the routing clock to go off.
!
! 1.23 L. Webber, 14-Jul-81
! Map in Hopcost in COSTCH; change calls to MAPIN to MAP$'s.
!
! 1.24 L. Webber, 28-Jul-81
! Re-map Hopcost after calling $XPECLN in ROUTES.
!
! 1.25 L. Webber, 5-Aug-81
! Ignore "line up" CCB if the circuit isn't in TC state.
!
! 1.26 L. Webber, 11-Sep-81
! Fix ROUTES so that OL goes "unspecified" when a node becomes
! unreachable.
!
! 1.27 L. Webber, 17-Sep-81
! Add support for Phase2_node flag in node data base.
!
! 1.28 L. Webber, 23-Sep-81
! Add code to flag a node as "adjacent Phase II" when a circuit
! comes up, and in ROUTES to make a node reachable if that flag
! is on. The purpose of this change is to make Phase II nodes
! reachable to the local DN20 (and to all adjacent Phase II nodes)
! but to mark them not reachable in the DN20's routing messages.
!
! 1.29 L. Webber, 24-Sep-81
! Modify event logging code to use new macros for preparing the
! Event Buffer.
!
! 1.30 L. Webber, 6-Oct-81
! Fix LINEDN to make a Phase II node unreachable when its connecting
! circuit goes down.
!
! 1.31 L. Webber, 20-Oct-81
! Use the (new) "Reset" bit in LINEflags rather than Nty to determine
! when a line going down had an adjacent Phase II node (Nty is zeroed
! by Line Support).
!
! 1.32 L. Webber, 9-Nov-81
! Fix dot bug in 1.31.
!
! 1.33 L. Webber, 21-Dec-81
! Call CLN_RETRY for "Phase II" circuits in LINEDN.
!
! 1.34 L. Webber, 23-Feb-82
! Add DLLquota maintenance.
!
! 1.35 L. Webber, 8-Mar-82
! Don't process routing message if the input circuit is down.
!
! 1.36 L. Webber, 31-Mar-82
! Call $XPECLN when a Phase II circuit goes down (since "node down"
! doesn't handle in in that case).
!
! 1.37 A. Peckham, 19-Apr-82
! Eliminate references to LOG_EVENT, GETLINE, GETNODE.
! PKTA_HDR has gone to XPE. Make local call now.
! Optimize ROUTES and friends.
!
! 1.38 A. Peckham, 23-Aug-82
! Fix bug in ROUTES which shows up as low core being modified (4:0 6:1).
! The check for a $MCB_PAUSE allowed the loop on nodes to go beyond NN.
! This ended up requesting the data base for a non-exisistent node,
! which would produce a zero address for NODEb.
! Move the _SYNQH check up to the top of the loop.
!
! 1.39 A. Peckham, 16-Sep-82
! Add support for internal feature: SET NODE blah MAXIMUM ADDRESS num.
! This causes XPT to ignore nodes above 'num' when it receives a
! routing message from node 'blah'.
!
!--
!
! INCLUDE FILES:
!
require 'XPTMAC';
!
! TABLE OF CONTENTS
!
forward routine
ROUTES: novalue,
CHECK: novalue,
LINEDN: CALL$ novalue,
LINEUP: CALL$ novalue,
RCVROU: CALL$ novalue,
COSTCH: CALL$ novalue,
OPENT: CALL$ novalue,
CLOSET: CALL$ novalue,
DECTIM: CALL$ novalue,
SET_EACH_Srm_FLAG: novalue,
SIGNAL_REACHABILITY: novalue,
VALID_BUFFER;
!
! MACROS:
!
!
! EQUATED SYMBOLS:
!
!
! OWN STORAGE:
!
!
! EXTERNAL REFERENCES:
!
external _SYNQH; ! Synch queue header
external routine
$XPECLN: CALL$ novalue,
CLN_RETRY: novalue,
TERM_XPT: novalue;
global routine ROUTES: novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Determines the reachability and output line for each destination
! node.
!
! This routine may have to be invoked multiple times to perform a single
! resolution of the routing data base. If a process needs to be
! dispatched at synch level, ROUTES will do an $MCB_PAUSE. MCB will call
! ROUTES back at synch level (with no other invocations of Transport
! intervening), at which time more nodes will be processed until all NN
! are done.
!
! FORMAL PARAMETERS
!
! NONE.
!
! IMPLICIT INPUTS
!
! Hop - 2x2 matrix containing the hops to each node over each line.
! Cost - 2x2 matrix containing the cost to each node over each line.
! Minhop - vector containing the fewest hops to each destination.
! Mincost - vector containing the least cost to each destination.
! Maxh - Maximum number of hops (network diameter)
! Maxc - Maximum cost to destination
! Infh - Value denoting "infinite" hops
! Infc - Value denoting "infinite" cost
! Reach - vector containing the reachability for a destination.
! NN - maximum node address; number of rows in the matrices.
!
! MaxN - maximum node address that has been processed so far.
! IncN - work variable
! Synchblk - the Synch block used to reschedule this routine.
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! Modifies matrices Hop and Cost. Sometimes modifies vectors Minhop,
! Mincost, Reach, OL and Srm.
!
!--
begin
require 'XPTSYM';
bind Hopcost = Hopcost_address: matrix;
local I;
MAP$(HOPcost_bias); !Map in the matrix
I = .MaxN; !Calculate starting node
if .I eql 0
then begin
IncN = 0; ! Initialize pause count if starting
Routing_changed = FALSE;
end;
do begin ! Process while synch queue is empty
local NODEb: ref NODEblock, Cost, Hops, Index;
if ._SYNQH neqa 0 ! If devices need attention
then begin ! then
MaxN = .I; ! save where we are
IncN = .IncN + 1; ! and give them a chance.
$MCB_PAUSE(.Synchblk,.ROUTESaddr);
return;
end;
I = .I + 1; ! Increment node address
Index = 0; ! Index for new line
Hops = Infh; ! Minimum hops
Cost = Infc; ! Minimum cost
begin
local CNT,X: ref vector;
CNT = NLN + 1; ! Lines to do
X = Hopcost[.I,0,.CNT - 1]; ! (Note: .CNT-1 optimizes code
do ! instead of NLN)
begin ! Do this for all lines
local Y; ! including the local.
Y = .X[0];
Y = .Y<Hop_P,Hop_S>; ! Isolate hops over this line
if .Hops gtr .Y then Hops = .Y; ! and get minimum.
Y = .X[0];
X = X[1]; ! (get bliss-16 to auto-increment)%
Y = .Y<Cost_P,Cost_S>; ! Isolate cost over this line
if .Cost gtr .Y ! and if this path is better
then
begin ! then
Cost = .Y; ! save better cost
Index = .CNT; ! and better line.
end;
end
while (CNT = .CNT - 1) neq 0; ! (optimizes in bliss-16)
end;
if .Hops gtr .Maxh ! If too far away
then begin
Hops = Infh; ! then make unreachable
Index = 0; ! with no line.
end;
if .Cost gtr .Maxc ! If too costly
then begin
Cost = Infc; ! then make unreachable
Index = 0; ! with no line.
end;
if (Index = .Index - 1) geq 0 ! figure line number
then begin
Index = -.Index; ! (while producing
Index = .Index + NLN; ! optimal bliss-16 code).
end;
begin
local NODEb: ref NODEblock;
NODEb = $XPT_GET_NODE_DB(.I); ! Get the affected node.
if .Phase2_node ! If phase II node,
then Index = .OL; ! it is still reachable.
if .Index geq 0 ! If there is a path
then ! then
begin
if not .Reach ! If reachability change
then
begin ! then
Reach = TRUE;
SIGNAL_REACHABILITY(.I,1); ! log an event.
end;
end
else
begin
if .Reach ! If reachability change
then
begin ! then
Reach = FALSE;
SIGNAL_REACHABILITY(.I,0); ! log an event.
end;
end;
if (.Minhop neq .Hops) or (.Mincost neq .Cost) ! Changes in these
then ! cause
begin ! new routing messages
Routing_changed = TRUE; ! to be sent.
Minhop = .Hops; ! Set new values.
Mincost = .Cost;
end;
if not .Local_node
then OL = .Index; ! Reachable through this line.
end;
end
while .I lssu NN;
if .Routing_changed then SET_EACH_Srm_FLAG();
MaxN = 0;
end; !End of ROUTES
routine CHECK: novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Detects any corruption of column 0 (transport users) in the Hop and
! Cost matrices.
!
! FORMAL PARAMETERS
!
! NONE.
!
! IMPLICIT INPUTS
!
! Hop - 2x2 matrix giving the number of hops to a destination
! over a line.
! Cost - 2x2 matrix giving the cost to a destination over a line.
! User - vector indicating node addresses associated with transport
! users rather than remote systems
! Infh - value used as "infinite" number of hops
! Infc - value used as "infinite" cost
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! If column 0 in either matrix is corrupted, terminate Transport.
!
!--
begin
require 'XPTSYM';
bind Hopcost = Hopcost_address: matrix;
bind Limit = NLN;
MAP$(HOPcost_bias);
decr I from NN to 1 do begin
local NODEb: ref NODEblock;
local X;
NODEb = $XPT_GET_NODE_DB(.I); ! Address node data base entry
X = .Hopcost[.I,0,Limit]; ! Pick up entry from matrix
if
(if .Local_node then
if .X neq 0
then TRUE
else FALSE
else
if .X neq ((Infh^Hop_P) or (Infc^Cost_P))
then TRUE
else FALSE)
then (BPT(XPT$_CHECK); CALL$L(TERM_XPT));
end;
end; !End of CHECK
global routine LINEDN (CCB): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Processes a "line down" event from Transport Initialization.
!
! FORMAL PARAMETERS
!
! CCB[C_LIN] - Line number being declared down.
!
! IMPLICIT INPUTS
!
! Hop,Cost,Infh,Infc
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! Sets column LINE of Hop and Cost to "infinite";
! recalculates routing.
!
!--
begin
local NODEb,LINEb;
require 'XPTSYM';
require 'MCBCOM';
bind Hopcost = Hopcost_address: matrix;
Check(); !Make sure column 0 of the matrices is OK.
LINEb = $XPT_GET_LINE_DB(.CCB[C_LIN]);
NODEb = $XPT_GET_NODE_DB(.Nid);
Line_up = false;
Srm = false;
Send_hello = false;
Service_line = false;
Hello_clock = 0;
decr I from NN to 1 do
Hopcost[.I,.LINEnumber,NLN] = ! Make routing impossible
((Infh^Hop_P) or (Infc^Cost_P));! over the line
if .Phase2_node
then begin ! Phase II node:
CLN_RETRY(.LINEb); ! clean out the retry queue
$XPECLN(.Nid,0); ! send DC for each active link
Reach = false; ! Cancel reachability
Phase2_node = false;
end;
ROUTES(); ! Recalculate the data bases
CCB[C_FNC] = FC_RCE; ! Send down
CCB[C_STS] = CS_SUC; ! "line down complete"
$MCB_SCHEDULE_CCB(.CCB); ! indication
end; !End of LINEDN
global routine LINEUP (CCB): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Processes a "line up" indication from Transport Initialization.
!
! FORMAL PARAMETERS
!
! CCB[C_LIN] - line being declared up.
!
! IMPLICIT INPUTS
!
! Hop,Cost,Nty,Lcv,Srm,Nid
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! Initializes column J of the routing data base;
! recalculates routing.
!
!
!--
begin
map CCB: ref block field (C_XPT_fields);
local NODEb,LINEb;
require 'XPTSYM';
CHECK(); !Make sure column 0 of matrices is OK
LINEb = $XPT_GET_LINE_DB(.CCB[C_LIN]); ! Address line data base entry
!
! If the line has gone down again, ignore line up
!
if .LINEstate eql TC
then begin
!
! Otherwise - process the line up
!
NODEb = $XPT_GET_NODE_DB(.Nid);
Phase2_node = false;
selectone .Nty of
set
[PhTwo]: ! Adjacent node is Phase II:
begin ! Don't include in routing data base.
Phase2_node = true; ! It can talk to Phase II nodes.
Reach = TRUE; ! Accessable
OL = .LINEnumber; ! over this line
end;
[Full]:
Send_hello = true;
[otherwise]:
begin ! Adjacent node is not full routing:
bind Hopcost = Hopcost_address: matrix;
if .Lcv gtr 0 ! If the cost is positive then
then ! that's the cost to the adjacent node
Hopcost[.Nid,.LINEnumber,NLN] = (.Lcv^Cost_P + 1^Hop_P)
else ! otherwise
CALL$L(TERM_XPT); ! corruption!
if .Nty eql Small
then Send_hello = true;
end;
tes;
SET_EACH_Srm_FLAG();
Hello_clock = .Hello_timer;
Line_up = true;
$NM_LOG_BEGIN();
PARAMETER_CM(3,1); ! Log a
PARAMETER_DU_2(,Nid); ! "line up"
$NM_LOG_END(4^6+$XPT$E_LUP,.NMXid);
ROUTES(); ! Recalculate routing data base
end;
CCB[C_FNC] = FC_RCE; !Send "line up
CCB[C_STS] = CS_SUC; ! complete" to
$MCB_SCHEDULE_CCB(.CCB); ! Transport Line Interface
end; !End of LINEUP
global routine RCVROU (CCB): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Processes a received routing message.
!
! FORMAL PARAMETERS
!
! CCB[C_LIN] - line message was received on
! CCB[C_BIAS] - descriptor for message
!
! IMPLICIT INPUTS
!
! Hop,Cost,Lcv
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! Updates routing data base from routing message;
! recalculates routing
!
!--
begin
local LINEb;
require 'XPTSYM';
require 'MCBCOM';
bind Hopcost = Hopcost_address: matrix;
local BUFPTR,BUFLEN,NO_NODES;
pointer PTR;
!
! Validate data base
!
CHECK(); !Make sure column 0 is OK
!
! If the circuit is down, ignore the message
!
LINEb = $XPT_GET_LINE_DB(.CCB[C_LIN]); ! Address line data base entry
if .LINEstate eql RU then begin
!
! Validate the message
!
MAPBUF(.CCB,BUFPTR,BUFLEN); !Map to and address buffer
if .Lcv lss 0 then !Line cost negative -
CALL$L(TERM_XPT) ! bring down transport
else if VALID_BUFFER(.CCB,.BUFPTR,.BUFLEN) !Make sure buffer is good
then begin
!
! Copy message fields into routing data base
!
begin ! Get number of nodes to process
local ADR;
bind MXA = NO_NODES: ref vector;
PTR = ch$plus(.BUFPTR,1); ! Bump past control header
ADR = getw(PTR);
if (MXA = .NODEmaximum_address_vector) neqa 0
then begin
if (MXA = .MXA [.ADR - 1]) neq 0
then begin
if .MXA gtr NN
then MXA = NN;
end
else MXA = NN;
end
else MXA = NN;
NO_NODES = minu (.MXA, (.BUFLEN-5)^-1);
end;
incr I from 1 to NN do
begin
local TEMP,COSTI;
bind HOPI = TEMP; ! (for optimization)
TEMP = ((Infh^Hop_P) or (Infc^Cost_P)); ! assume not accessable.
if .I leq .NO_NODES
then begin
MAP$(.CCB[C_BIAS]); ! Map in the buffer
TEMP = getw(PTR); ! Pick up next routing field
COSTI = .TEMP<Cost_P,Cost_S>; ! COST subfield
HOPI = .TEMP<Hop_P,Hop_S>; ! HOP subfield
COSTI = .COSTI+.Lcv; ! Add in our cost
HOPI = .HOPI+1; ! and one more hop.
if .COSTI gtru Infc ! Top off
then COSTI = Infc;
if .HOPI gtru Infh ! if necessary.
then HOPI = Infh;
COSTI = .COSTI^Cost_P; ! Position
HOPI = .HOPI^Hop_P; ! and
TEMP = .HOPI; ! reconstruct.
TEMP = .TEMP+.COSTI;
end;
MAP$(HOPcost_bias); ! Map in the Hop/Cost matrix
Hopcost[.I,.LINEnumber,NLN] = .TEMP; ! and update it
end;
ROUTES(); !Recalculate routing
end;
end;
!
! Clean up the accounting and return the buffer
!
INPUTcount = .INPUTcount - 1; ! Decrement outstanding buffers
DLLquota = .DLLquota + 1; ! and increment global quota
CCB[C_FNC] = FC_RCE; ! Return buffer
$MCB_SCHEDULE_CCB(.CCB); ! to TLI
end; !End of RCVROU
global routine COSTCH (LINE,COSTJ): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Processes a cost change for a line
!
! FORMAL PARAMETERS
!
! LINE Line cost change is for
! COSTJ New cost for line
!
! IMPLICIT INPUTS
!
! Cost, Lcv
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! Updates Cost and Lcv; recalculates routing.
!
!--
begin
local LINEb;
require 'XPTSYM';
bind Hopcost = Hopcost_address: matrix;
!
! Validate new and old costs for line
!
LINEb = $XPT_GET_LINE_DB(.LINE); ! Address line data base entry
if (.COSTJ leq 0) or (.Lcv leq 0) then
CALL$L(TERM_XPT)
!
! Update data base for cost change
!
else begin
bind DIF = .COSTJ - .Lcv;
Lcv = .COSTJ;
MAP$(HOPcost_bias);
decr I from NN to 1 do !Update Cost matrix as well
(Hopcost[.I,.LINE,NLN])<Cost_P,Cost_S> =
.(Hopcost[.I,.LINE,NLN])<Cost_P,Cost_S> + DIF;
end;
!
! Make sure timer goes off to recalculate routes
!
Routing_clock = 1;
end; !End of COSTCH
global routine OPENT (CCB): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Opens a transport port to identify a local transport user.
!
! FORMAL PARAMETERS
!
! CCB Function CCB for the open.
!
! IMPLICIT INPUTS
!
! User,Hop,Cost
!
! ROUTINE VALUE: Acceptance or rejection of the open
! COMPLETION CODES:
!
! TRUE - Open accepted.
! FALSE - Open rejected.
!
! SIDE EFFECTS:
!
! Updates User,Hop and Cost; recalculates routing.
!
!--
begin
map CCB: ref block field (C_FIELDS);
local NODEb;
require 'XPTSYM';
bind Hopcost = Hopcost_address: matrix;
!
! Validate routing data base
!
CHECK();
NODEb = $XPT_GET_NODE_DB(.CCB[C_PRM1]); ! Address node data base entry
if .Local_node ! Address already in use -
then return SIGNAL_STOP (CE_ERR); ! reject request
!
! Update data base entries for this user
!
Local_node = TRUE;
User = .CCB[C_PIX]; ! Save process ID for user
Hopcost[.CCB[C_PRM1],0,NLN] = 0; ! Free to get to local user
ROUTES(); ! Recalculate routing
CCB [C_STS] = CS_SUC;
!
! Terminate function CCB
!
CCB[C_FNC] = FC_CCP;
$MCB_SCHEDULE_CCB(.CCB);
end; !End of OPENT
global routine CLOSET (CCB): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Processes close of a port for a transport user.
!
! FORMAL PARAMETERS
!
! CCB Function CCB for the close.
!
! IMPLICIT INPUTS
!
! User,Hop,Cost
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! Updates User,Hop,Cost; recalculates routing.
!
!--
begin
local NODEb;
require 'XPTSYM';
require 'MCBCOM';
bind Hopcost = Hopcost_address: matrix;
local RET;
!
! Validate routing data base
!
CHECK();
NODEb = $XPT_GET_NODE_DB(.CCB[C_PRM1]); ! Address node data base entry
if not .Local_node ! Continue only if port is local
then return SIGNAL_STOP (CE_ERR); ! Invalid node address - abort function
!
! Update routing data base
!
Local_node = FALSE;
User = 0;
Hopcost[.CCB[C_PRM1],0,NLN] = ! Can't get there
((Infh^Hop_P) or (Infc^Cost_P)); ! from here
ROUTES(); ! Recalculate routing
CCB [C_STS] = CS_SUC;
!
! Terminate function CCB
!
CCB[C_FNC] = FC_CCP;
$MCB_SCHEDULE_CCB(.CCB);
end; !End of CLOSET
global routine DECTIM: CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Processes a timer call for the Decision Module. A call here does
! not necessarily mean any timer has expired.
!
! FORMAL PARAMETERS
!
! NONE.
!
! IMPLICIT INPUTS
!
! LINEflags, Routing_clock
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! If Routing_clock has expired, set each Srm flag, restart the timer
! and recalculate routing.
!
!--
begin
require 'XPTSYM';
CHECK(); ! Make sure the data base's OK
SET_EACH_Srm_FLAG(); ! Ask that routing messages be sent
ROUTES(); ! Recalculate routing
end; ! End of DECTIM
routine SET_EACH_Srm_FLAG: novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Set the bit on each line requesting a routing message to be sent.
!
! FORMAL PARAMETERS
!
! None
!
! IMPLICIT INPUTS
!
! None
!
! ROUTINE VALUE: Success/failure
! COMPLETION CODES:
!
! None
!
! SIDE EFFECTS:
!
! None
!
!--
begin
require 'XPTSYM';
$XPT_for_each_LINEb_do_begin
Srm = true; ! Signal "send a routing message"
$XPT_next_LINEb_end;
end; !End of SET_EACH_Srm_FLAG
routine SIGNAL_REACHABILITY (NODE,STATUS): novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Logs a reachability event
! and cleans up links for the node if transition to unreachable.
!
! FORMAL PARAMETERS
!
! NODE - Number of unreachable node
! STATUS - 0/transition to reachable, 1/transition to unreachable
!
! IMPLICIT INPUTS
!
! None
!
! ROUTINE VALUE: Success/failure
! COMPLETION CODES:
!
! None
!
! SIDE EFFECTS:
!
! None
!
!--
begin
require 'XPTSYM';
$NM_LOG_BEGIN();
PARAMETER_C_1(7,STATUS);
$NM_LOG_END(4^6+$XPT$E_NRC,.NODE);
if .STATUS neq 0
then
begin
$XPECLN(.NODE,0);
MAP$(HOPcost_bias);
end;
end; !End of SIGNAL_REACHABILITY
routine VALID_BUFFER (CCB,BUFPTR,BUFLEN) =
!++
! FUNCTIONAL DESCRIPTION:
!
! Validates a routing message:
! 1) Checks the control header
! 2) Validates the checksum
! 3) Determines that the message contains no more than NN entries,
! except for unreachable ones.
! In cases 1 and 2, an invalid message brings down the line it came
! over. In case 3, entries after NN are ignored anyway, and reachable
! entries (Hops neq Infh or Cost neq Infc) will cause an error to be
! logged.
!
! FORMAL PARAMETERS
!
! BUFPTR - character pointer to buffer to be examined
! BUFLEN - length of message in buffer (equal to 2*N+5 where N
! is the number of routing entries in the message)
!
! IMPLICIT INPUTS
!
! Nid
!
! ROUTINE VALUE: Success/failure
! COMPLETION CODES:
!
! TRUE - message is valid
! FALSE - message is flawed; do not use it.
!
! SIDE EFFECTS:
!
! If the buffer is not valid, an error will be logged;
! if it is really bad (tests 1 or 2 fail) its line will
! be dropped.
!
!--
begin
local LINEb;
require 'XPTSYM';
require 'MCBCOM';
local CTLHDR,NO_NODES,PTR,RET,SUM;
LINEb = $XPT_GET_LINE_DB(.CCB[C_LIN]); ! Address line table entry
PTR = .BUFPTR; ! Initialize work pointer
CTLHDR = getb(PTR); ! Pick up transport control header
if biton(.CTLHDR,%o'360') then RET = 1 ! Reserved bits on
else if getw(PTR) neq .Nid then ! Invalid source node
RET = 3
else begin
local P;
P = .PTR;
NO_NODES = (.BUFLEN-5)^-1; !Calculate number of cells in message
SUM = 0; !Initialize checksum
decr I from .NO_NODES to 1 do !Calculate
checksum(SUM,getw(P)); ! checksum
if .SUM neq getw(P) then RET = 2 !Checksum doesn't match one in message
else if .NO_NODES leq NN then !Message doesn't overextend data base,
RET = 0 ! message is valid
else begin !Message reports on extra nodes:
local NNN;
NNN = 0; ! Assume no reachable nodes past NN
P=ch$plus(ch$plus(.PTR,NN),NN); ! Point past nodes we know about
incr I from NN+1 to .NO_NODES do! Scan for the
(if (getw(P) neq ! greatest node
((Infh^Hop_P) or (Infc^Cost_P)))!address that
then NNN = .I); ! is reachable
if .NNN eql 0 then !All extra entries
RET = 0 ! are unreachable
else RET = 4 + .NNN !Some entry is real - that's bad
end
end;
!
! Message is no good - signal an event and maybe restart the line
!
if .RET neq 0 then begin
$NM_LOG_BEGIN();
$NM_LOG_END (4^6+
(selectone .RET of
set
[1]: begin ! Routing message format error:
COUNTER_INCREMENT(XPTDB,XPTfmt_loss); ! Increment packet counter
CALL$L(PKTA_HDR,.BUFPTR); ! Log packet hdr in Event Buffer
$XPT$E_FMT
end;
[2]: begin ! Checksum error:
bind THREE = uplit(3);
COUNTER_INCREMENT(LINEb,XPTlinedn);! Increment "line downs" counter
PARAMETER_C_1(5,THREE);
CALL$L(PKTA_HDR,.BUFPTR); ! Move in packet header
$XPT$E_LSF
end;
[3]: begin ! Invalid source node:
COUNTER_INCREMENT(LINEb,XPTlinedn);! Increment "line downs" counter
PARAMETER_CM(4,1); ! Move in as
PARAMETER_DU_2(,Nid); ! expected node ID
PARAMETER_C_1(5,uplit(4)); ! Move in reason code
CALL$L(PKTA_HDR,.BUFPTR); ! Move in packet header
$XPT$E_LOF
end;
[otherwise]: begin ! Partial update loss:
local NNN;
COUNTER_INCREMENT(XPTDB,XPTrout_loss); ! Increment counter
CALL$L(PKTA_HDR,.BUFPTR); ! Move packet header into buffer
NNN = .RET-4; ! Move in highest reachable
PARAMETER_DU_2(2,NNN); ! node address
$XPT$E_RUL
end;
tes),.NMXid);
if .RET lss 4 ! Message is really bad:
then begin ! Re-initialize.
Service_line = true;
return FALSE
end;
end;
TRUE ! Acceptable message - give OK
end; ! End of VALID_BUFFER
end !End of module XPTDEC
eludom