MULTICS TECHNICAL BULLETIN                              MTB750-01

  To:       MTB Distribution

  From:     Maggie Sharpe
            Stan Cox
            Doug Parisek

  Date:     April 3, 1987

  Subject:  Message Coordinator Changes for MR12.1 (DSA)


  This MTB proposes changes to Message Coordinator (MC) software to
  support DSA channels.  There are  two major sets of changes.  The
  bulk  of the  change is   the introduction  of virtual  channels.
  Several MC commands must be  modified to recognize and operate on
  virtual  channels.   The  smaller  changes  involves  creation of
  pending entries in the mc_anstbl.

  Virtual channels are accessed through  the use of "-operator" and
  "-virtual_channel  <virtual channel  name>" control  arguments to
  the "login" pre-access command.  Only the login_server is made to
  accept  these control  arguments,  thus  they are  only available
  through  DSA  connections.   MTB-751,  The  MNA Answering Service
  Modifications,  and  MTB-752,  Network   Login  Servers,  may  be
  referenced for more details in this area.

| Revisions to  this MTB detail the  function of the two  new login
| pre-access    command   control    arguments,   -operator,    and
| -virtual_channel.  Also, the  new operator command, "accept_vchn"
| is  defined in  more detail.    This revision  also explains  the
| circumstances under  which a user will  be automatically accepted
| although the "vchn_requires_accept" installation parm is on.


  Comments should be sent to the authors:

  via Forum:
     >udd>Multics>rjck>meetings>mnet on System-M


  Multics project  internal documentation; not to  be reproduced or
  distributed outside the Multics project without permission of the
  Director of MDC.

  MTB750-01                                      MC Changes for DSA



     1:  Introduction  . . . . . . . . . . . . . . . . . . . . .   1
     2:  The Problems  . . . . . . . . . . . . . . . . . . . . .   1
     2.1:  Support For "dial system" . . . . . . . . . . . . . .   1
     2.2:  Pre-accepting MC terminals through Network lines  . .   2
     3:  The Solution  . . . . . . . . . . . . . . . . . . . . .   2
     3.1:  Some Notes on Security  . . . . . . . . . . . . . . .   3
     4:  Implementation  . . . . . . . . . . . . . . . . . . . .   4
|    4.1:  Info files  . . . . . . . . . . . . . . . . . . . . .   6
     4.2:  Include files . . . . . . . . . . . . . . . . . . . .   7
     4.2.1:  mc_anstbl.incl.pl1  . . . . . . . . . . . . . . . .   7
     4.2.2:  dial_event_message.incl.pl1 . . . . . . . . . . . .   9
     4.2.3:  net_event_message.incl.pl1  . . . . . . . . . . . .  10
     4.2.4:  installation_parms.incl.pl1 . . . . . . . . . . . .  13
     4.3:  Summary of other modifications  . . . . . . . . . . .  13
     4.3.1:  new calling sequences . . . . . . . . . . . . . . .  13
        mc_commands_ . . . . . . . . . . . . . . . . . . . . . .  14
           new_tty . . . . . . . . . . . . . . . . . . . . . . .  14
           remove_tty  . . . . . . . . . . . . . . . . . . . . .  14
           mc_login  . . . . . . . . . . . . . . . . . . . . . .  15
           substty . . . . . . . . . . . . . . . . . . . . . . .  16
           new_vchn  . . . . . . . . . . . . . . . . . . . . . .  17
     4.3.2:  Changes to other modules  . . . . . . . . . . . . .  18
     4.4:  Examples of MC commands . . . . . . . . . . . . . . .  20

  MC Changes for DSA                                      MTB750-01


  The message coordinator (MC) is  the body of software that allows
  operators  to  dial  into  the  Initializer  process  and execute
  operator commands  from a remote  terminal, i.e., other  than the
  system console.

  Currently,  there are  two ways  to obtain  an MC  terminal.  The
  first method is  to designate certain channels as  MC channels in
  the  CDT by  setting the   cdte.service_type for  the channel  to
  MC_SERVICE.   The operator  "accept" command  may be  used at any
  time  to  register  this  channel  in  the  mc_anstbl.   (This is
  sometimes  done in  the system   start up.)   A terminal  on this
  channel   can  accept   operator  input   or  display  pre-routed
  information as soon as it is turned on.

  The second method is to use  the "dial system { -user <user_id>}"
  pre-access command.  A message such  as "Channel a.h004 dialed to
  Initializer" will subsequently be  printed on the system console.
  The system operator  may then use the "accept"  or "drop" command
  to approve or to reject  the request respectively.  At some sites
  the  operators are  required to  "sign on"  on MC  terminals upon

  Throughout this document, we will use the term "operator" to mean
  an authenticated operator, i.e., one who  is signed on or able to
  use an authenticated MC terminal.   The term "user" will apply to
  anyone else accessing or seeking to access Multics.


  The basic  problem is to  make various MC  commands recognize DSA
  channel  names.   They  are  of  the  form  DSA.<session  control
  name>.<session number>,  e.g.  DSA.MUL1.0004.  Only  the commands
  have   been  taught   to  distinguish   DSA  channels   by  name.
  Subroutines  that are  called by  the commands,  and the programs
  that  handle wakeups,  e.g.,  mc_tty_  and mc_wakeups,  use other
  information in the mc_ate  (MC answer_table entry) to distinguish
  MCS lines from network  lines.  This scheme isolates DSA-specific
  code in a small portion of the programs.

  In  addition, there  are two  other problems  to be  addressed to
  support  MC service  over DSA  lines.  The  simple problem  is to
  support the "dial system ..."  mechanism.  The more difficult one
  is to provide a means of pre-accepting MC terminals.

  2.1:  Support For "dial system"

  When the  "dial system ..."   pre-access command is  used from an
  MCS channel, the cdte.current_service type for the channel is set

  MTB750-01                                      MC Changes for DSA

  to  "MC_SERVICE".   The  MC  will  only  comply  with the "accept
  x.xxxx" command  if the cdte.current_service has  the said value.
  The  problem facing  us is  that there  is no  CDT entry  for DSA
  channels, so the dial is recorded  in the mc_anstbl.  An entry is
  created  in the mc_anstbl  and a new  flag, "pending", is  set to
  distinguish the channel from "active" ones.

  2.2:  Pre-accepting MC terminals through Network lines

  Unless a channel  is hardwired, it is not  feasible to pre-accept
  it for MC connections.  In network environments, the channel name
  assigned  to   a  particular  connection  does   not  necessarily
  correspond  to the  user or  the exact  physical location  of the

  Clearly,  the  alternative,  the  "dial   /  accept  /  sign  on"
  combination  is rather  cumbersome.  It  is also  not a practical
  solution for  sites that make  extensive use of  virtual consoles
  and   pre-route  various   output  streams   to  pre-accepted  MC

  Furthermore, because DSA channel  names are dynamic, the "Channel
  DSA.MUL1.0004  dialed to  initializer" message,  would not convey
  enough information to the system  operator who is to approve/deny
  the  connection.   This  is  why  the  login  server requires the
  "-user" control  argument on the  "dial system" command.   Use of
  this control argument causes the user's user_id to be included in
  the message displayed on the system console.


  To  resolve the  problem with   channel names,  we introduce  the
  concept of virtual channels.  Like tty channels, virtual channels
  can  be   pre-accepted,  using  the  "accept"   command,  and  be
  designated as a destination of a virtual console using the define
  operator  command.  This  can be  done before  or after  they are
  actually connected  to a process.   Virtual channel names  may be
  any ascii strings that do not contain a period (".").  This is to
  simplify distinguishing real and virtual channel names.

  The  only problem  then is  accessing the  virtual channel.   One
  possible  solution would be  to add a  "-virtual_channel" control
  argument to the dial command.   Of course, this control arg would
  be used only in conjunction  with the "dial system" special case.
  This  was  not  deemed  an  elegant  solution  and  was therefore

  Instead,   we   have   chosen   to   add   the   "-operator"  and
  "-virtual_channel"  control arguments  to the  "login" pre-access
  command.  "login <user_id> -operator"  will now be the equivalent

  MC Changes for DSA                                      MTB750-01

  of "dial  system -user <user_id>".  The user  is authenticated by
  the  answering service,  so a  subsequent "sign  on" will  not be
  required.  The user  must have the operator attribute  in the PNT
  to use this control argument.

  The "-operator" and "-virtual_channel" control arguments are only
  available  when logging  in over  a network  channel.  Only login
  servers  recognize these control  arguments and pass  the correct
  information to the answering service  (AS).  (Please refer to MTB
  752 for details  on the interaction between the  Login Server and
| the  Answering  Service.)   -operator,  -op  specifies  that  the
| terminal the  operator is logging  in on should  be authenticated
| for operator  or message coordinator use.  The  operator must use
| the accept  initializer command (from another  terminal which has
| already  been authenticated)  to  approve  this request.   If the
| -vchannel  control argument (described  below) is also  used, and
| the specified  virtual channel has been  preaccepted, the request
| is automatically  accepted.  The vchn_requires_accept  keyword in
| the installation_parms  segment may be  used to require  a manual
| "accept" by  a validated operator whenever  the "login -operator"
| command is issued by someone other than the operator signed on at
| the  bootload  console.   The  -operator  control  argument  also
| eliminates the need for the  operator to use a subsequent sign_on
| initializer  command.   The  operator  must  have  the "operator"
| attribute in the PNT to use the -operator control argument.
| -vchannel STR, -vchn STR identifies the virtual channel specified
| by STR as the one to be  used to connect the terminal to Multics.
| For example,  the command line  below specifies that  the virtual
| channel vchn1 is to be  associated with the terminal the operator
| is currently logging in on.
|         l Smith -op -vchn vchn1
| The  -operator   control  argument  (described  above)   must  be
| specified or the -vchannel control argument will not be accepted.

  3.1:  Some Notes on Security

  The use of the "-user" control argument with the dial command for
  MCS  channels is  regulated by   the Check_acs  parameter in  the
  CMF.(1)   The  operator  "sign  on"  requirement  depends  on the
  "vchn_requires_accept"  installation  parameter.   Therefore,  on
  sites  where security  is an   important issue,  accessing an  MC
  terminal via  the "dial system"  method requires a  user to enter


  (1) The Network  Information Table (NIT) has  a similar parameter
      to Check_acs which  regulates the use of "-user"  on the dial
      command when the dial_identifier is not "system".

  MTB750-01                                      MC Changes for DSA

  the  user_id and  password twice.   The MC  has been  modified to
  authenticate  the user  exactly once.   (A sign_on  will still be
  required  after the  maximum inactive  time for  the operator has

  This allows anyone eligible to sign on as an operator to do so at
  any  time.  Where  this may  be a  problem, sites  are allowed to
  further  restrict  the  use  of  virtual  channels  by  using the
  "vchn_requires_accept" installation  parm.  In this case,  if the
  user  is  not  already  "signed  on"  on  another MC terminal, an
| "accept" by  an authenticated operator is required.   If the user
| is already "signed on" on another  MC terminal and he attempts to
| sign_on to  another MC terminal via  the -virtual_channel control
| argument, and the "vchn_requires_accept" installation parm is ON,
| he will be automatically accepted  as long as the virtual channel
| was pre-defined for MC use  via the "accept_vchn" command.  If an
  "accept"  is  required,  a  pending  entry  is  created  for this
  channel.   On  the  other  hand,   when  a  user  connects  to  a
  pre-accepted terminal without  operator intervention, the message
  "Channel  x.xxxx dialed  to Initializer  (<user_id> ACCEPTED)" is
  displayed on the system console.

  In addition, a new command, "accept_vchn", may be used instead of
  "accept".  In this case the virtual channel is created and may be
  specified  in  any  subsequent  "define"  and  "route"  commands.
  However,  the "vchn_requires_accept" flag  for the entry  will be
  turned on.   This flag overrides all  other conditions, requiring
| an operator to "accept" the  channel before it is connected.  The
| command is similar in syntax and functionality to the initializer
| "accept"  command.   The  difference  is  that  the "accept_vchn"
| command is  used to preaccept  terminal device channels  that are
| virtual channels,  while the "accept"  command is used  to accept
| terminal  device channels  with "real"  channel identifiers.  The
| syntax  of the  accept_vchn command  is defined  below.  See also
| "Preaccepting Terminals Associated With  DSA Channels" in section
| 8 of the DSA Admin Guide for additional information on the use of
| the "accept_vchn" command.


  When the -op  control arg is used, the login  server will send an
  "operator request"  to the AS, requesting validation  of the user
  as an operator.   If the user can be validated  then the AS calls
  the new entrypoint mc_commands_$mc_logins, to inform the MC.  The
  calling sequence is as follows:

  call mc_commands_$mc_login (physical_channel_name, operator_name,
  vchn_name,  login_server_procid, ls_term_ev_chn,  ls_resp_ev_chn,
  ls_handle, code)

  MC Changes for DSA                                      MTB750-01

  If no virtual  channel is used, a pending entry  is created.  The
  message "Channel  <chn_id> dialed to initializer  (<user_id>)" is
  displayed  on the  console.  If  a virtual  channel is specified,
  then   it  must  already   exist  in  the   mc_anstbl,  otherwise
  error_table_$vchn_not_found is returned.   If the virtual channel
  exists  but  is  currently  in  use,  error_table_$vchn_active is
  returned.  In  these two cases the Answering  Service will inform
  the Login Server of the unsuccessful validation.

  If  the mc_ate.vchn_requires_accept and  the vchn_requires_accept
  installation parm are both OFF,  the user is automatically signed
  on and the message
     Channel <chn_id> dialed to initializer (<user_id> ACCEPTED)
  is     displayed      on     the     system      console.      If
  mc_ate.vchn_requires_accept is ON, the  login must be accepted by
  the   operator.    Otherwise,    when   the   Installation   Parm
  vchn_requires_accept is ON, the login must be accepted unless the
  user is already signed on another authorized MC terminal.

  When a terminal is accepted, or  when a pending entry is dropped,
  the    approval/rejection    response    is    sent    over   the
  mc_ate.ls_resp_event_chn  to the  login server  via an  "operator
  response".  If, on the other hand, a terminal is dropped after it
  has  been  accepted,  a  termination  response  is  sent over the

  MTB750-01                                      MC Changes for DSA

| 4.1:  Info files
| ___________                                           ___________
| accept_vchn                                           accept_vchn
| ___________                                           ___________
| accept_vchn virtual_channel_name {authorization} {target}
|    {bc_list}
| accepts a virtual terminal device  channel and connects it to the
| message coordinator's  device complement.  This command  can only
| be used in ring 4.
| virtual_channel_name
|    is the name of a virtual channel.  The name can be up to 32
|    characters long.  It cannot include periods (.).  This
|    argument cannot be set to "otw_" because "otw_" is reserved
|    for the bootload console.
| authorization
|    specifies the authorization which should be assigned to this
|    virtual channel.  It must be one of the following:
|    full
|       the device is able to issue all intializer commands.  This
|       is the default.
|    none
|       no commands are allowed.
|    reply
|       only the reply command is allowed.
|    query
|       only the who and hmu commands are allowed.
|    daemon
|       only the reply, intercom, and exec commands are allowed.
|  target
|     specifies the source name identifying the daemon to which
|     reply commands will be directed.  This argument is used for

  MC Changes for DSA                                      MTB750-01

|     terminals dedicated to the control of a single I/O daemon.
|     The default name is *.
|  bc_list
|     specifies that a broadcast list should be used.  This list
|     identifies channels to which will be sent copies of input
|     entered at the terminal associated with virtual_channel_name.
|     If the bc_list argument is set to a broadcast list, both
|     virtual channels and DSA channel_ids can be used.  Each
|     channel name can be up to 32 characters in length.  Up to ten
|     channel names can be specified, separated by commas.  If the
|     bc_list argument is set to "none", the current broadcast list
|     is cleared.  If the bc_list argument is not specified, the
|     broadcast list previously specified (if any) remains
|     unchanged.
| The example below specifies that  operator commands to the backup
| daemon  can be  submitted from  the terminal  associated with the
| virtual channel vchn1.
|    accept_vchn vchn1 reply bk

  4.2:  Include files

  Three include files must be modified.  The proposed modifications
  are marked by change bars described below.

  4.2.1:  MC_ANSTBL.INCL.PL1

     dcl    1 mc_anstbl                   based (mc_ansp) aligned,
              2 max_size                  fixed bin,
              2 current_size              fixed bin,
              2 mc_procid                 bit (36),
              2 sysdir                    char (168),
              2 mrtp                      ptr,
              2 vconsp                    ptr,
              2 cons_cont_proc            entry,
              2 con_rec,
                3 mc_ate_ptr              ptr,
                3 ec_id                   fixed bin (71),
                3 seq_num                 fixed bin (35),
                3 offset                  bit (18),
                3 flags,
                  4 enabled               bit (1) unaligned,
                  4 active                bit (1) unaligned,
              2 n_sources                 fixed bin,
              2 max_sources               fixed bin,
              2 current_time              fixed bin (71),

  MTB750-01                                      MC Changes for DSA

              2 trace                     bit (1) aligned,
              2 pad                       (30) bit (36) aligned,
              2 entry                     (0 refer
                                          aligned like mc_ate;

     dcl    1 mc_ate                      based (mc_atep) aligned,
              2 flags                     aligned,
  |             3 virtual                 bit (1) unaligned,
  |             3 pending                 bit (1) unaligned,
                3 active                  bit (1) unaligned,
                3 the_system_console      bit (1) unaligned,
                3 a_system_console        bit (1) unaligned,
                3 pad001                  bit (1) unaligned,
                3 signed_on               bit (1) unaligned,
                3 reply_restricted        bit (1) unaligned,
                3 broadcast               bit (1) unaligned,
                3 broadcast_all           bit (1) unaligned,
  |             3 vchn_requires_accept    bit (1) unaligned,
                3 pad                     bit (25) unaligned,
  |           2 virtual_tty_name          char (32) unaligned,
  |           2 real_tty_name             char (32) unaligned,
              2 cdtep                     pointer,
              2 iocb                      pointer,
              2 sci_ptr                   pointer,
              2 tra_vec                   fixed bin,
              2 restrict_reply            char (32),
              2 n_casts                   fixed bin,
              2 cast                      (10) char (32),
              2 oper_info,
                3 personid                char (32),
                3 last_input_time         fixed bin (71),
              2 queue_ptr                 ptr,
              2 queue_event               fixed bin (71),
              2 event                     fixed binary (71),
  |           2 ls_procid                 bit (36),
  |           2 ls_term_ev_chn            fixed bin (71),
  |           2 ls_resp_ev_chn            fixed bin (71),
  |           2 ls_handle                 bit (72),
              2 authority,
                3 privilege               (36) bit (1) unaligned,
              2 control,
                3 inhibit                 bit (1) unal,
                3 output_wait             bit (1) unal,
                3 output_pending          bit (1) unal,
                3 unused                  bit (33) unal;

  declare   (
            MC_WAIT_DIALUP                init (1),
            MC_WAIT_ANSWERBACK            init (2),
            MC_WAIT_READY                 init (3),
            MC_WAIT_COMMAND               init (4)

  MC Changes for DSA                                      MTB750-01

            )                             fixed bin int static
                                          options (constant);


            Distinguishes  virtual channels  from "real"  channels.

            Distinguishes  pending channels  from active  channels.
            If a login is pending on a virtual channel, both active
            and pending flags are on.  (NEW)

            Requires  the operator  to accept  or reject  the dial.

            Is the name of the  virtual channel for this entry.  If
            no virtual channel is used,  this has the same value as
            real_tty_name.   Only   this  name  may  be   used  for
            destinations of virtual consoles.(NEW)

            Is  the name of  the actual communications  channel for
            this entry.  (Replaces mc_ate.tty_name)

  ls_procid Process_id of the login server who will wake us up with
            connect  and  disconnect  --   used  only  for  network
            channels.  (NEW)

            Event  channel  to  send  terminate  response  to login
            server.  (NEW)

            Event  channel  to  send  operator  response  to  login
            server.  (NEW)

  ls_handle The login server handle for this connection.  (NEW)


  /*  This  include  file  describes  the  event  message  sent  by
  dial_ctl_ and login servers */

  dcl dial_event_message_ptr pointer;

  MTB750-01                                      MC Changes for DSA

       dcl 1 dial_event_message
                           aligned based (dial_event_message_ptr),
             2 description char (6) unaligned,
             2 flags       unal,
               3 error_msg bit (1), /* indicates description field
                           contains standard error code */
               3 ls_msg    bit (1), /* indicates message from login
                           server, name in user_message */
               3 control   bit (15);


            is the event message description.

  error_msg indicates  descripion  field  contains  standard  error

  ls_msg    indicates message from the login server

  control   can be one of the constants defined below.

  /* overlay  of description, contains unique  part of user_message
  handle if any */

  dcl    dial_event_message_handle   bit    (54)   aligned    based

  /* possible values for dial_event_message.control */

  dcl (JUST_DIALED bit (15) aligned initial ("77770"b3),

       JUST_HUNGUP bit (15) aligned initial ("77771"b3),
       DIALS_ALLOWED bit (15) aligned initial ("77772"b3),
       DIALS_DENIED bit (15) aligned initial ("77773"b3)
       ) internal static options (constant);


  dcl net_event_message_arg fixed bin (71); /* For calling IPC */

  dcl NET_EVENT_MESSAGE_VERSION_1  bit (2) internal  static options
  (constant) init ("10"b);

       dcl 1 net_event_message
                             aligned based (addr
             2 version     bit (2) unaligned,

  MC Changes for DSA                                      MTB750-01

             2 reason      bit (16) unaligned,
             2 pad         bit (4) unaligned,
             2 network_type
                           fixed bin (4) unsigned unaligned,
             2 type        fixed bin (8) unsigned unaligned,
             2 handle      fixed bin (35) aligned;


            is the type of network.  See below for constants.

  type      is the type of interupt.  See below for constants.

  handle    is the caller's handle (devx for MCS, handle for DSA).

  /* Network type constants */

  dcl  MCS_NETWORK_TYPE           fixed  bin (4)  unsigned internal
                                static options (constant) init (0);
  dcl  DSA_NETWORK_TYPE           fixed  bin (4)  unsigned internal
                                static options (constant) init (1);

  /* MCS event message type constants */

  dcl  MAX_MCS_EVENT_MSG_TYPE     fixed bin internal static options
                                (constant) init (8);
  dcl  MCS_UNSPECIFIED_MSG        fixed bin internal static options
                                (constant)  init (0);  /* used  for
                                "start" order, etc.  */
  dcl  MCS_DIALUP_MSG             fixed bin internal static options
                                (constant) init (1); /* dialup */
  dcl  MCS_HANGUP_MSG             fixed bin internal static options
                                (constant) init (2); /* hangup */
  dcl  MCS_DIALOUT_MSG            fixed bin internal static options
                                (constant)  init  (3);  /*  dialout
                                status returned */
  dcl  MCS_QUIT_MSG               fixed bin internal static options
                                (constant) init (4); /* quit */
  dcl  MCS_READ_MSG               fixed bin internal static options
                                (constant)   init  (5);   /*  input
                                arrived */
  dcl  MCS_WRITE_MSG              fixed bin internal static options
                                (constant)  init   (6);  /*  output
                                completed */
  dcl  MCS_LINE_STATUS_MSG        fixed bin internal static options
                                (constant)  init  (7);  /*  control
                                tables sent status */
  dcl  MCS_MASKED_MSG             fixed bin internal static options
                                (constant) init (8);
                                 /* 0 */
                                "dialup", /* 1 */

  MTB750-01                                      MC Changes for DSA

                                "hangup", /* 2 */
                                "dialout status", /* 3 */
                                "quit", /* 4 */
                                "read", /* 5 */
                                "write", /* 6 */
                                "line status", /* 7 */
  dcl  DSA_RESUME_MSG             fixed bin (8) uns internal static
                                options (constant) init (10);
  dcl  DSA_RESUME_ACK_MSG         fixed bin (8) uns internal static
                                options (constant) init (11);
  dcl  DSA_SUSPEND_MSG            fixed bin (8) uns internal static
                                options (constant) init (12);
  dcl  DSA_SUSPEND_ACK_MSG        fixed bin (8) uns internal static
                                options (constant) init (13);
  dcl  DSA_TERM_ABNORMAL_MSG      fixed bin (8) uns internal static
                                options (constant) init (14);
  dcl  DSA_ESTABLISHMENT_MSG      fixed bin (8) uns internal static
                                options (constant) init (15);
  dcl  DSA_TERMINATED_MSG         fixed bin (8) uns internal static
                                options (constant) init (16);
  dcl  DSA_USER_UNASSIGN_MSG      fixed bin (8) uns internal static
                                options (constant) init (17);
  dcl  DSA_DATA_INPUT_MSG         fixed bin (8) uns internal static
                                options (constant) init (18);
  dcl  DSA_DATA_OUTPUT_MSG        fixed bin (8) uns internal static
                                options (constant) init (19);

  dcl  DSA_MSG_TYPE_TO_PNAME      (0:19) char  (20) internal static
                                options       (constant)       init
                                /* 0 */
                                "attention", /* 1 */
                                "data_attention", /* 2 */
                                "demand_release_sru", /* 3 */
                                "demand_turn", /* 4 */
                                "demand_turn_ack", /* 5 */
                                "purge", /* 6 */
                                "recover", /* 7 */
                                "recover_ack", /* 8 */
                                "release_sru", /* 9 */
                                "resume", /* 10 */
                                "resume_ack", /* 11 */
                                "suspend", /* 12 */
                                "suspend_ack", /* 13 */
                                "terminate_abnormal", /* 14 */
                                "establishment", /* 15 */
                                "terminated", /* 16 */
                                "user_unassign", /* 17 */
                                "data input", /* 18 */
                                "data output"); /* 19 */

  MC Changes for DSA                                      MTB750-01


       installation_parms.vchn_requires_accept bit (1) aligned.
  If  TRUE, an  operator must   accept/drop all  "login -op  -vchn"
  attempts.   The  space  for  this  parameter  is  taken  from the
  installation_parms.end_pad component.

  4.3:  Summary of other modifications

  This section contains the calling  sequences for new and modified
  subroutines,  and  short  descriptions   of  all  other  modified


  MTB750-01                                      MC Changes for DSA

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

  Name:  mc_commands_


  Entry:  mc_commands_$new_tty


       dcl  mc_commands_$new_tty entry (char (*), bit (36), bit (1)
                 al, ptr, fixed bin (35));

       call mc_commands_$new_tty (channel_id, authority, cdte_flag,
                 mc_ate_ptr, code);


  cdte_flag           (New Input Parameter)
            If "1"b  then channel_id is an  MCS channel; otherwise,
            it is a network channel.


  Entry:  mc_commands_$remove_tty


       dcl  mc_commands_$remove_tty entry (fixed bin (71), bit (1)
                 al, fixed bin (35));

       call mc_commands_$remove_tty (channel_id, drop_flag, code);


  drop_flag           (New Input Parameter)
            If "1"b  then disconnect the terminal.   Currently, the
            terminal is dropped in  admin_$drop after the mc_ate is
            deleted.   This will no  longer be possible  as network

  MC Changes for DSA                                      MTB750-01

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

            channels  require   information  from  the   mc_ate  to
            disconnect  the terminal.    The drop_flag  is required
            because  mc_commands_$remove_tty  is   also  called  by
            mc_tty_  when a  terminal hangs  up.  In  this case the
            disconnection step  must be omitted.  Updating  the CDT
            entry is still done in mc_tty_ in this case.


  Entry:  mc_commands_$mc_login

       This new entrypoint validates the user as an operator.


       dcl  mc_commands_$mc_login entry (char (*), char (*), char
                 (*), bit (36), fixed bin (71), fixed bin (71), bit
                 (72), fixed bin (35));

       call mc_commands_$mc_login (physical_channel_name,
                 operator_name, vchn_name, login_server_procid,
                 ls_term_ev_chn, ls_resp_ev_chn, ls_handle, code);


            is the actual name of the channel, e.g., dsa.MUL1.0006.
            This name will be saved in mc_ate.real_tty_name.

            is the person_id of the user attempting to access an MC
            terminal.     This    name    will    be    saved    in

  vchn_name is the name  of the virtual channel to be  used.  If it
            is  blank,  a  virtual  channel  is  not requested, and
            mc_ate.virtual_tty_name   will   be    set   equal   to

            is  the process_id  of the  login server  who owns this

  MTB750-01                                      MC Changes for DSA

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

            is  the event  channel over  which we  send termination
            responses  to the login  server.  This would  happen if
            the operator drops a terminal already in MC service.

            is  the  event  channel  over  which  we  send operator
            responses to the login  server.  This would happen when
            the operator accepts or drops a channel pending accept,
            or when a terminal is automatically accepted.

  ls_handle The handle for communicating with the login server.

  code      is a standard system error code.


  Entry:  mc_commands_$substty


       dcl  mc_commands_$substty entry (char (*), char (*), bit
                 (1), ptr, bit (1), fixed bin (35));

       call mc_commands_$substty (remove_channel,
                 replacement_channel, cdte_flag, mc_ate_ptr,
                 drop_flag, code);


  cdte_flag           (New Input Parameter)
            If "1"b  then channel_id is an  MCS channel; otherwise,
            it  is  a  network  channel.   This  parameter  is also
            described in the new_tty entrypoint.

  drop_flag           (New Input Parameter)
            If "1"b  then disconnect the terminal.   This parameter
            is also described in the remove_tty entrypoint.

  MC Changes for DSA                                      MTB750-01

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

  Entry:  mc_commands_$new_vchn

       This       new      entrypoint       is      called       by
  operator_mc_cmds_$accept_vchn  which behaves  exactly as  accept,
  except that it  accepts only virtual channel names  and calls the
  mc_commands_$new_vchn   instead  of   mc_commands_$new_tty.   The
  parameters  are  the  same  as  mc_commands_$new_tty  except that
  cdte_flag is not needed.

  The  two entries differ  only in that  mc_commands_$new_vchn sets
  mc_ate.flags.vchn_requires_accept to TRUE.


       dcl  mc_commands_$new_vchn entry (char (*), bit (36), ptr,
                 fixed bin (35));

       call mc_commands_$new_vchn (channel_id, authority,
                 cdte_flag, mc_ate_ptr, code);


  MTB750-01                                      MC Changes for DSA

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________


    o  admin_
            Because admin_  has become too large to  compile with a
            complete symbol table, we will be taking the MC related
            commands    out    and    into    the    new    module,
            operator_mc_cmds_.   These commands  are accept,  drop,
            substty,  define, redefine,  undefine, route,  deroute,
            and  reroute.  (This is  the subject of  MCR7407.)  The
            new  command, accept_vchn will  also be placed  in this

    o  mc_tty_
            to distinguish  network event messages form  tty_ ones.
            net_event_message.incl.pl1 was modified to help mc_tty_
            decode the event types.

            to accept  wakeups from the  login server who  owns the
            channel and from session_control.

            to create the iocb for network channels after receiving
            the DIALUP  wakeup from the login  server.  MCS channel
            support the listen control  order which can be executed
            before the channel is actually connected.

            to  read the  answerback for  all network  channels; if
            answerbacks  are supported,  to set  the terminal type,
            otherwise to set the default terminal type for the line
            type.   Because  DSA  does   not  support  setting  the
            terminal  type after  connection, if  the line  type is
            DSA, the "stty" is skipped.

    o  bound_system_control_::sc_request_table_.alm
            Modify  to  reflect  the  changes  made  to admin_.pl1.

    o  sc_requests_$go
            to   initialize    sc_stat_$vchn_requires_accept   from

    o  bound_system_control_::sc_requests_$self_identify
            to identify  the virtual channel name  when an operator
            types a "."  on an MC terminal.  The full message looks

  MC Changes for DSA                                      MTB750-01

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

            system control:  channel DSA.MUL1.0004 (virtual channel
            BKC_VCHN) signed on.

            The paranthetical expression will not be displayed if a
            virtual channel is not in use.

    o  bound_system_control_::sc_stat_.alm:
            Modify  to  define  sc_stat_$vchn_requires_accept.   It
            represents  the value of  the installation parm  by the
            same name.

    o  bound_system_control_::sc_process_command_line_.pl1
            Modify   to   use   mc_ate.real_tty_name   instead   of

    o  bound_as_mc_::mc_con_rec_.pl1
            Recompile with  new mc_anstbl.incl.pl1.  Change  to not
            call hpchs_ entries if the test answering service is in

    o  bound_as_mc_ mc_quiesce_.pl1:
            Recompile with new mc_anstbl.incl.pl1.

    o  bound_as_mc_::mc_util_.pl1:
            Modify    to    use    new    calling    sequence   for

    o  bound_as_mc_::mc_wakeups_.pl1
            Modify  to use  the mc_ate.virtual_tty_name  instead of
            mc_ate.tty_name.   Fixed  bug  in  "router"  entrypoint
            which loses  the source name in messages  when the last
            destination  for a virtual  console is deleted  and the
            output reverts to the default virtual console.

    o  bound_as_mc_::restart_mc_ttys_.pl1:
            Recompiled with new mc_anstbl.incl.pl1.

    o  bound_as_mc_::display_mc_anstbl.pl1
            Modify to display pending entries by default (Currently
            only  active entries  are printed  by default).   Also,
            modify to accept "-pending"  control argument and, when
            specified, to display any pending entries.

    o  error_table_.alm
            Add two new error codes:

  MTB750-01                                      MC Changes for DSA

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

                 "Specified    virtual     channel    is    already
                 active/pending."   Used when   a user  specifies a
                 virtual channel that is  already in use or pending
                 an accept on the login command.

                 "Specified virtual channel  is not defined."  Used
                 when  a user specifies  a virtual channel  that is
                 not defined in the mc_anstbl on the login command.

  4.4:  Examples of MC commands

  A  site  wishes  to  use  an  MC  terminal  for  all  output from
  Backup.SysDaemon.  Channel a.h004 is to be used for this purpose.
  It is located in a safe  location and the site can pre-accept the
  terminal with no concern for its security.

  The  site  would  include  the  following  lines  in  the  system

  accept a.h004                 (register   the    terminal.    The
                                cdte.service_type  for   a.h004  is
  accept a.h005                 (register   another  MC   terminal.
                                Same service_type as above.)
  define BK_VCONS tty a.h004    (define a new  virtual console or a
                                new  destination  for  an  existing
                                one.  Up to 32 virtual consoles may
                                be defined.)
  route bk stream_i/o BK_VCONS  (route the output from source bk to
                                this virtual console)
  Note:  When logging in Backup.SysDaemon, "bk" (from the route example above)
       is used  for the source_id parameter.  All  output from this
       instance  of  Backup.SysDaemon  will  be  saved  in  a queue
       segment  for a.h004.   When a  terminal comes  up on channel
       a.h004, the  saved output and any subsequent  output will be
       displayed on it.

       Examples  of the remaining  MC commands follow:   (The other
       "accept",  "route"  and  "define"  statements  establish the
       background for examples for "deroute", "reroute", "undefine"
       and "redefine".)
  define BK_ERR_VCONS tty a.h004
  define BK_ERR_VCONS tty a.h005

  MC Changes for DSA                                      MTB750-01

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

                                (define  another  virtual  console;
                                establish a.h004 and  a.h005 as its
                                destinations.  Each  vcons may have
                                up to 8  destinations.  Each source
                                may  be  associated  with  up  to 8
                                virtual consoles.)

  route bk error_output BK_ERR_VCONS
                                (Up to 16 sources may be defined in
                                the Message Routing Table.)
  reroute bk error_output BK_ERR_VCONS BK_VCONS
                                (error_output from bk  will be sent
                                to     BK_VCONS      instead     of
  route bk error_output BK_ERR_VCONS
                                (error output from  bk will be sent
                                to both.)
  redefine BK_ERR_VCONS a.h005 a.h004
                                (everything routed  to BK_ERR_VCONS
                                will   go  to  a.h004   instead  of
                                a.h005.   This means that  2 copies
                                of  bk  error_output   will  go  to
                                a.h004:   one  from  BK_VCONS,  the
                                other from BK_ERR_VCONS.)
  deroute bk error_output BK_VCONS
                                (do  not  send  bk  error_output to
  undefine BK_ERR_VCONS a.h004  (remove a.h004 from the destination
                                list of BK_ERR_VCONS.)
  drop a.h005                   (remove   a.h005  from   all  vcons
                                entries;   remove   the   mc_anstbl
                                entry;  disconnect  the  line.   It
                                must  be  "accepted"  and "defined"
                                again before it can be used.)

  The following  examples demonstrating the usage  of "substty" and
  other uses of  "accept", "drop" would not be placed  in the start

  USER: login JSmith -op        (User is  on channel dsa.MUL1.0006.
                                The  operator  is  informed  of the
  OPER: accept dsa.MUL1.0006    (a.h006  may now  be used  to enter
                                any system control commands.)
  OPER: substty a.h004 dsa.MUL1.0006
                                (If  for  some  reason  a.h004 went
                                down, this  command may be  used to

  MTB750-01                                      MC Changes for DSA

  ____________                                         ____________

  mc_commands_                                         mc_commands_
  ____________                                         ____________

                                send  all   queued  and  subsequent
                                messages     for      a.h004     to
                                dsa.MUL1.0006 instead.)
  USER: login LHacker -op       (User on dsa.MUL1.0007)
  OPER: drop dsa.MUL1.0007      (Operator  does not  wish to  allow
                                this  user to  use an  MC terminal.
                                This  command  removes  the pending
                                entry  and  sends  a  rejection  to
                                login server's  operator validation
  OPER: drop dsa.MUL1.0006      (We  are done  with this  terminal.
                                The  mc_ate is  removed; the  login
                                server  is requested  to disconnect
                                the channel.)