text: /* sim_tmxr.c: Telnet terminal multiplexor library
  
     Copyright (c) 2001-2008, Robert M Supnik
  
     Permission is hereby granted, free of charge, to any person obtaining a
     copy of this software and associated documentation files (the "Software"),
     to deal in the Software without restriction, including without limitation
     the rights to use, copy, modify, merge, publish, distribute, sublicense,
     and/or sell copies of the Software, and to permit persons to whom the
     Software is furnished to do so, subject to the following conditions:
  
     The above copyright notice and this permission notice shall be included in
     all copies or substantial portions of the Software.
  
     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
     IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
     CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  
     Except as contained in this notice, the name of Robert M Supnik shall not be
     used in advertising or otherwise to promote the sale, use or other dealings
     in this Software without prior written authorization from Robert M Supnik.
  
     Based on the original DZ11 simulator by Thord Nilson, as updated by
     Arthur Krewat.
  
     20-Nov-08    RMS     Added three new standardized SHOW routines
     30-Sep-08    JDB     Reverted tmxr_find_ldsc to original implementation
     27-May-08    JDB     Added line connection order to tmxr_poll_conn,
                          added tmxr_set_lnorder and tmxr_show_lnorder
     14-May-08    JDB     Print device and line to which connection was made
     11-Apr-07    JDB     Worked around Telnet negotiation problem with QCTerm
     16-Aug-05    RMS     Fixed C++ declaration and cast problems
     29-Jun-05    RMS     Extended tmxr_dscln to support unit array devices
                          Fixed bug in SET LOG/NOLOG
     04-Jan-04    RMS     Changed TMXR ldsc to be pointer to linedesc array
                          Added tmxr_linemsg, circular output pointers, logging
                          (from Mark Pizzolato)
     29-Dec-03    RMS     Added output stall support
     01-Nov-03    RMS     Cleaned up attach routine
     09-Mar-03    RMS     Fixed bug in SHOW CONN
     22-Dec-02    RMS     Fixed bugs in IAC+IAC receive and transmit sequences
                          Added support for received break (all from by Mark Pizzolato)
                          Fixed bug in attach
     31-Oct-02    RMS     Fixed bug in 8b (binary) support
     22-Aug-02    RMS     Added tmxr_open_master, tmxr_close_master
     30-Dec-01    RMS     Added tmxr_fstats, tmxr_dscln, renamed tmxr_fstatus
     03-Dec-01    RMS     Changed tmxr_fconns for extended SET/SHOW
     20-Oct-01    RMS     Fixed bugs in read logic (found by Thord Nilson).
                          Added tmxr_rqln, tmxr_tqln
  
     This library includes:
  
     tmxr_poll_conn -     poll for connection
     tmxr_reset_ln -      reset line
     tmxr_getc_ln -       get character for line
     tmxr_poll_rx -       poll receive
     tmxr_putc_ln -       put character for line
     tmxr_poll_tx -       poll transmit
     tmxr_open_master -   open master connection
     tmxr_close_master -  close master connection
     tmxr_attach  -       attach terminal multiplexor
     tmxr_detach  -       detach terminal multiplexor
     tmxr_ex      -       (null) examine
     tmxr_dep     -       (null) deposit
     tmxr_msg     -       send message to socket
     tmxr_linemsg -       send message to line
     tmxr_fconns  -       output connection status
     tmxr_fstats  -       output connection statistics
     tmxr_dscln   -       disconnect line (SET routine)
     tmxr_rqln    -       number of available characters for line
     tmxr_tqln    -       number of buffered characters for line
     tmxr_set_lnorder -   set line connection order
     tmxr_show_lnorder -  show line connection order
  
     All routines are OS-independent.
  */
  
  #include "sim_defs.h"
  #include "sim_sock.h"
  #include "sim_tmxr.h"
  #include "scp.h"
  #include <ctype.h>
  
  /* Telnet protocol constants - negatives are for init'ing signed char data */
  
  #define TN_IAC          -1                              /* protocol delim */
  #define TN_DONT         -2                              /* dont */
  #define TN_DO           -3                              /* do */
  #define TN_WONT         -4                              /* wont */
  #define TN_WILL         -5                              /* will */
  #define TN_BRK          -13                             /* break */
  #define TN_BIN          0                               /* bin */
  #define TN_ECHO         1                               /* echo */
  #define TN_SGA          3                               /* sga */
  #define TN_LINE         34                              /* line mode */
  #define TN_CR           015                             /* carriage return */
  #define TN_LF           012                             /* line feed */
  #define TN_NUL          000                             /* null */
  
  /* Telnet line states */
  
  #define TNS_NORM        000                             /* normal */
  #define TNS_IAC         001                             /* IAC seen */
  #define TNS_WILL        002                             /* WILL seen */
  #define TNS_WONT        003                             /* WONT seen */
  #define TNS_SKIP        004                             /* skip next cmd */
  #define TNS_CRPAD       005                             /* CR padding */
  
  void tmxr_rmvrc (TMLN *lp, int32 p);
  int32 tmxr_send_buffered_data (TMLN *lp);
  TMLN *tmxr_find_ldsc (UNIT *uptr, int32 val, TMXR *mp);
  
  extern int32 sim_switches;
  extern char sim_name[];
  extern FILE *sim_log;
  extern uint32 sim_os_msec (void);
  
  /* Poll for new connection
  
     Called from unit service routine to test for new connection
  
     Inputs:
          *mp     =       pointer to terminal multiplexor descriptor
     Outputs:
          line number activated, -1 if none
  
     If a connection order is defined for the descriptor, and the first value is
     not -1 (indicating default order), then the order array is used to find an
     open line.  Otherwise, a search is made of all lines in numerical sequence.
  */
  
  int32 tmxr_poll_conn (TMXR *mp)
  {
  SOCKET newsock;
  TMLN *lp;
  int32 *op;
  int32 i, j;
  uint32 ipaddr;
  static char mantra[] = {
      TN_IAC, TN_WILL, TN_LINE,
      TN_IAC, TN_WILL, TN_SGA,
      TN_IAC, TN_WILL, TN_ECHO,
      TN_IAC, TN_WILL, TN_BIN,
      TN_IAC, TN_DO, TN_BIN
      };
  
  newsock = sim_accept_conn (mp->master, &ipaddr);        /* poll connect */
  if (newsock != INVALID_SOCKET) {                        /* got a live one? */
      op = mp->lnorder;                                   /* get line connection order list pointer */
      i = mp->lines;                                      /* play it safe in case lines == 0 */
  
      for (j = 0; j < mp->lines; j++, i++) {              /* find next avail line */
          if (op && (*op >= 0) && (*op < mp->lines))      /* order list present and valid? */
              i = *op++;                                  /* get next line in list to try */
          else                                            /* no list or not used or range error */
              i = j;                                      /* get next sequential line */
  
          lp = mp->ldsc + i;                              /* get pointer to line descriptor */
          if (lp->conn == 0)                              /* is the line available? */
              break;                                      /* yes, so stop search */
          }
  
      if (i >= mp->lines) {                               /* all busy? */
          tmxr_msg (newsock, "All connections busy\r\n");
          sim_close_sock (newsock, 0);
          }
      else {
          lp = mp->ldsc + i;                              /* get line desc */
          lp->conn = newsock;                             /* record connection */
          lp->ipad = ipaddr;                              /* ip address */
          lp->cnms = sim_os_msec ();                      /* time of conn */
          lp->rxbpr = lp->rxbpi = 0;                      /* init buf pointers */
          lp->txbpr = lp->txbpi = 0;
          lp->rxcnt = lp->txcnt = 0;                      /* init counters */
          lp->tsta = 0;                                   /* init telnet state */
          lp->xmte = 1;                                   /* enable transmit */
          lp->dstb = 0;                                   /* default bin mode */
          sim_write_sock (newsock, mantra, 15);
          tmxr_linemsg (lp, "\n\r\nConnected to the ");
          tmxr_linemsg (lp, sim_name);
          tmxr_linemsg (lp, " simulator ");
  
          if (mp->dptr) {                                 /* device defined? */
              tmxr_linemsg (lp, sim_dname (mp->dptr));    /* report device name */
              tmxr_linemsg (lp, " device");
  
              if (mp->lines > 1) {                        /* more than one line? */
                  char line[20];
  
                  tmxr_linemsg (lp, ", line ");           /* report the line number */
                  sprintf (line, "%i", i);
                  tmxr_linemsg (lp, line);
                  }
              }
  
          tmxr_linemsg (lp, "\r\n\n");
  
          tmxr_poll_tx (mp);                              /* flush output */
          return i;
          }
      }                                                   /* end if newsock */
  return -1;
  }
  
  /* Reset line */
  
  void tmxr_reset_ln (TMLN *lp)
  {
  if (lp->txlog)                                          /* dump log */
      fflush (lp->txlog);
  tmxr_send_buffered_data (lp);                           /* send buffered data */
  sim_close_sock (lp->conn, 0);                           /* reset conn */
  lp->conn = lp->tsta = 0;                                /* reset state */
  lp->rxbpr = lp->rxbpi = 0;
  lp->txbpr = lp->txbpi = 0;
  lp->xmte = 1;
  lp->dstb = 0;
  return;
  }
  
  /* Get character from specific line
  
     Inputs:
          *lp     =       pointer to terminal line descriptor
     Output:
          valid + char, 0 if line
  */
  
  int32 tmxr_getc_ln (TMLN *lp)
  {
  int32 j, val = 0;
  uint32 tmp;
  
  if (lp->conn && lp->rcve) {                             /* conn & enb? */
      j = lp->rxbpi - lp->rxbpr;                          /* # input chrs */
      if (j) {                                            /* any? */
          tmp = lp->rxb[lp->rxbpr];                       /* get char */
          val = TMXR_VALID | (tmp & 0377);                /* valid + chr */
          if (lp->rbr[lp->rxbpr])                         /* break? */
              val = val | SCPE_BREAK;
          lp->rxbpr = lp->rxbpr + 1;                      /* adv pointer */
          }
      }                                                   /* end if conn */
  if (lp->rxbpi == lp->rxbpr)                             /* empty? zero ptrs */
      lp->rxbpi = lp->rxbpr = 0;
  return val;
  }
  
  /* Poll for input
  
     Inputs:
          *mp     =       pointer to terminal multiplexor descriptor
     Outputs:     none
  */
  
  void tmxr_poll_rx (TMXR *mp)
  {
  int32 i, nbytes, j;
  TMLN *lp;
  
  for (i = 0; i < mp->lines; i++) {                       /* loop thru lines */
      lp = mp->ldsc + i;                                  /* get line desc */
      if (!lp->conn || !lp->rcve)                         /* skip if !conn */
          continue;
  
      nbytes = 0;
      if (lp->rxbpi == 0)                                 /* need input? */
          nbytes = sim_read_sock (lp->conn,               /* yes, read */
              &(lp->rxb[lp->rxbpi]),                      /* leave spc for */
              TMXR_MAXBUF - TMXR_GUARD);                  /* Telnet cruft */
      else if (lp->tsta)                                  /* in Telnet seq? */
          nbytes = sim_read_sock (lp->conn,               /* yes, read to end */
              &(lp->rxb[lp->rxbpi]),
              TMXR_MAXBUF - lp->rxbpi);
      if (nbytes < 0)                                     /* closed? reset ln */
          tmxr_reset_ln (lp);
      else if (nbytes > 0) {                              /* if data rcvd */
          j = lp->rxbpi;                                  /* start of data */
          memset (&lp->rbr[j], 0, nbytes);                /* clear status */
          lp->rxbpi = lp->rxbpi + nbytes;                 /* adv pointers */
          lp->rxcnt = lp->rxcnt + nbytes;
  
  /* Examine new data, remove TELNET cruft before making input available */
  
          for (; j < lp->rxbpi; ) {                       /* loop thru char */
              signed char tmp = lp->rxb[j];               /* get char */
              switch (lp->tsta) {                         /* case tlnt state */
  
              case TNS_NORM:                              /* normal */
                  if (tmp == TN_IAC) {                    /* IAC? */
                      lp->tsta = TNS_IAC;                 /* change state */
                      tmxr_rmvrc (lp, j);                 /* remove char */
                      break;
                      }
                  if ((tmp == TN_CR) && lp->dstb)         /* CR, no bin */
                      lp->tsta = TNS_CRPAD;               /* skip pad char */
                  j = j + 1;                              /* advance j */
                  break;
  
              case TNS_IAC:                               /* IAC prev */
                  if ((tmp == TN_IAC) & !lp->dstb) {      /* IAC + IAC, bin? */
                      lp->tsta = TNS_NORM;                /* treat as normal */
                      j = j + 1;                          /* advance j */
                      break;                              /* keep IAC */
                      }
                  if (tmp == TN_BRK) {                    /* IAC + BRK? */
                      lp->tsta = TNS_NORM;                /* treat as normal */
                      lp->rxb[j] = 0;                     /* char is null */
                      lp->rbr[j] = 1;                     /* flag break */
                      j = j + 1;                          /* advance j */
                      break;
                      }
                  if (tmp == TN_WILL)                     /* IAC + WILL? */
                      lp->tsta = TNS_WILL;
                  else if (tmp == TN_WONT)                /* IAC + WONT? */
                      lp->tsta = TNS_WONT;
                  else lp->tsta = TNS_SKIP;               /* IAC + other */
                  tmxr_rmvrc (lp, j);                     /* remove char */
                  break;
  
              case TNS_WILL: case TNS_WONT:               /* IAC+WILL/WONT prev */
                  if (tmp == TN_BIN) {                    /* BIN? */
                      if (lp->tsta == TNS_WILL)
                          lp->dstb = 0;
                      else lp->dstb = 1;
                      }
  
              /* Negotiation with the HP terminal emulator "QCTerm" is not working.
                 QCTerm says "WONT BIN" but sends bare CRs.  RFC 854 says:
  
                   Note that "CR LF" or "CR NUL" is required in both directions
                   (in the default ASCII mode), to preserve the symmetry of the
                   NVT model.  ...The protocol requires that a NUL be inserted
                   following a CR not followed by a LF in the data stream.
  
                 Until full negotiation is implemented, we work around the problem
                 by checking the character following the CR in non-BIN mode and
                 strip it only if it is LF or NUL.  This should not affect
                 conforming clients.
              */
  
              case TNS_CRPAD:                             /* only LF or NUL should follow CR */
                  lp->tsta = TNS_NORM;                    /* next normal */
                  if ((tmp == TN_LF) ||                   /* CR + LF ? */
                      (tmp == TN_NUL))                    /* CR + NUL? */
                      tmxr_rmvrc (lp, j);                 /* remove it */
                  break;
  
              case TNS_SKIP: default:                     /* skip char */
                  lp->tsta = TNS_NORM;                    /* next normal */
                  tmxr_rmvrc (lp, j);                     /* remove char */
                  break;
                  }                                       /* end case state */
              }                                           /* end for char */
          }                                               /* end else nbytes */
      }                                                   /* end for lines */
  for (i = 0; i < mp->lines; i++) {                       /* loop thru lines */
      lp = mp->ldsc + i;                                  /* get line desc */
      if (lp->rxbpi == lp->rxbpr)                         /* if buf empty, */
          lp->rxbpi = lp->rxbpr = 0;                      /* reset pointers */
      }                                                   /* end for */
  return;
  }
  
  /* Return count of available characters for line */
  
  int32 tmxr_rqln (TMLN *lp)
  {
  return (lp->rxbpi - lp->rxbpr);
  }
  
  /* Remove character p (and matching status) from line l input buffer */
  
  void tmxr_rmvrc (TMLN *lp, int32 p)
  {
  for ( ; p < lp->rxbpi; p++) {
      lp->rxb[p] = lp->rxb[p + 1];
      lp->rbr[p] = lp->rbr[p + 1];
      }
  lp->rxbpi = lp->rxbpi - 1;
  return;
  }
  
  /* Store character in line buffer
  
     Inputs:
          *lp     =       pointer to line descriptor
          chr     =       characters
     Outputs:
          status  =       ok, connection lost, or stall
  */
  
  t_stat tmxr_putc_ln (TMLN *lp, int32 chr)
  {
  if (lp->txlog)                                          /* log if available */
      fputc (chr, lp->txlog);
  if (lp->conn == 0)                                      /* no conn? lost */
      return SCPE_LOST;
  if (tmxr_tqln (lp) < (TMXR_MAXBUF - 1)) {               /* room for char (+ IAC)? */
      lp->txb[lp->txbpi] = (char) chr;                    /* buffer char */
      lp->txbpi = lp->txbpi + 1;                          /* adv pointer */
      if (lp->txbpi >= TMXR_MAXBUF)                       /* wrap? */
          lp->txbpi = 0;
      if ((char) chr == TN_IAC) {                         /* IAC? */
          lp->txb[lp->txbpi] = (char) chr;                /* IAC + IAC */
          lp->txbpi = lp->txbpi + 1;                      /* adv pointer */
          if (lp->txbpi >= TMXR_MAXBUF)                   /* wrap? */
              lp->txbpi = 0;
          }
      if (tmxr_tqln (lp) > (TMXR_MAXBUF - TMXR_GUARD))    /* near full? */
          lp->xmte = 0;                                   /* disable line */
      return SCPE_OK;                                     /* char sent */
      }
  lp->xmte = 0;                                           /* no room, dsbl line */
  return SCPE_STALL;                                      /* char not sent */
  }
  
  /* Poll for output
  
     Inputs:
          *mp     =       pointer to terminal multiplexor descriptor
     Outputs:
          none
  */
  
  void tmxr_poll_tx (TMXR *mp)
  {
  int32 i, nbytes;
  TMLN *lp;
  
  for (i = 0; i < mp->lines; i++) {                       /* loop thru lines */
      lp = mp->ldsc + i;                                  /* get line desc */
      if (lp->conn == 0)                                  /* skip if !conn */
          continue;
          nbytes = tmxr_send_buffered_data (lp);          /* buffered bytes */
          if (nbytes == 0)                                /* buf empty? enab line */
              lp->xmte = 1;
          }                                               /* end for */
  return;
  }
  
  /* Send buffered data across network
  
     Inputs:
          *lp     =       pointer to line descriptor
     Outputs:
          returns number of bytes still buffered
  */
  
  int32 tmxr_send_buffered_data (TMLN *lp)
  {
  int32 nbytes, sbytes;
  
  nbytes = tmxr_tqln(lp);                                 /* avail bytes */
  if (nbytes) {                                           /* >0? write */
      if (lp->txbpr < lp->txbpi)                          /* no wrap? */
          sbytes = sim_write_sock (lp->conn,              /* write all data */
              &(lp->txb[lp->txbpr]), nbytes);
      else sbytes = sim_write_sock (lp->conn,             /* write to end buf */
              &(lp->txb[lp->txbpr]), TMXR_MAXBUF - lp->txbpr);
      if (sbytes != SOCKET_ERROR) {                       /* ok? */
          lp->txbpr = (lp->txbpr + sbytes);               /* update remove ptr */
          if (lp->txbpr >= TMXR_MAXBUF)                   /* wrap? */
              lp->txbpr = 0;
          lp->txcnt = lp->txcnt + sbytes;                 /* update counts */
          nbytes = nbytes - sbytes;
          }
      if (nbytes && (lp->txbpr == 0))     {               /* more data and wrap? */
          sbytes = sim_write_sock (lp->conn, lp->txb, nbytes);
          if (sbytes != SOCKET_ERROR) {                   /* ok */
              lp->txbpr = (lp->txbpr + sbytes);           /* update remove ptr */
              if (lp->txbpr >= TMXR_MAXBUF)               /* wrap? */
                  lp->txbpr = 0;
              lp->txcnt = lp->txcnt + sbytes;             /* update counts */
              nbytes = nbytes - sbytes;
              }
          }
      }                                                   /* end if nbytes */
  return nbytes;
  }
  
  /* Return count of buffered characters for line */
  
  int32 tmxr_tqln (TMLN *lp)
  {
  return (lp->txbpi - lp->txbpr + ((lp->txbpi < lp->txbpr)? TMXR_MAXBUF: 0));
  }
  
  /* Open master socket */
  
  t_stat tmxr_open_master (TMXR *mp, char *cptr)
  {
  int32 i, port;
  SOCKET sock;
  TMLN *lp;
  t_stat r;
  
  port = (int32) get_uint (cptr, 10, 65535, &r);          /* get port */
  if ((r != SCPE_OK) || (port == 0))
      return SCPE_ARG;
  sock = sim_master_sock (port);                          /* make master socket */
  if (sock == INVALID_SOCKET)                             /* open error */
      return SCPE_OPENERR;
  printf ("Listening on port %d (socket %d)\n", port, sock);
  if (sim_log)
      fprintf (sim_log, "Listening on port %d (socket %d)\n", port, sock);
  mp->port = port;                                        /* save port */
  mp->master = sock;                                      /* save master socket */
  for (i = 0; i < mp->lines; i++) {                       /* initialize lines */
      lp = mp->ldsc + i;
      lp->conn = lp->tsta = 0;
      lp->rxbpi = lp->rxbpr = 0;
      lp->txbpi = lp->txbpr = 0;
      lp->rxcnt = lp->txcnt = 0;
      lp->xmte = 1;
      lp->dstb = 0;
      }
  return SCPE_OK;
  }
  
  /* Attach unit to master socket */
  
  t_stat tmxr_attach (TMXR *mp, UNIT *uptr, char *cptr)
  {
  char* tptr;
  t_stat r;
  
  tptr = (char *) malloc (strlen (cptr) + 1);             /* get string buf */
  if (tptr == NULL)                                       /* no more mem? */
      return SCPE_MEM;
  r = tmxr_open_master (mp, cptr);                        /* open master socket */
  if (r != SCPE_OK) {                                     /* error? */
      free (tptr);                                        /* release buf */
      return SCPE_OPENERR;
      }
  strcpy (tptr, cptr);                                    /* copy port */
  uptr->filename = tptr;                                  /* save */
  uptr->flags = uptr->flags | UNIT_ATT;                   /* no more errors */
  
  if (mp->dptr == NULL)                                   /* has device been set? */
      mp->dptr = find_dev_from_unit (uptr);               /* no, so set device now */
  
  return SCPE_OK;
  }
  
  /* Close master socket */
  
  t_stat tmxr_close_master (TMXR *mp)
  {
  int32 i;
  TMLN *lp;
  
  for (i = 0; i < mp->lines; i++) {                       /* loop thru conn */
      lp = mp->ldsc + i;
      if (lp->conn) {
          tmxr_linemsg (lp, "\r\nDisconnected from the ");
          tmxr_linemsg (lp, sim_name);
          tmxr_linemsg (lp, " simulator\r\n\n");
          tmxr_reset_ln (lp);
          }                                               /* end if conn */
      }                                                   /* end for */
  sim_close_sock (mp->master, 1);                         /* close master socket */
  mp->master = 0;
  return SCPE_OK;
  }
  
  /* Detach unit from master socket */
  
  t_stat tmxr_detach (TMXR *mp, UNIT *uptr)
  {
  if (!(uptr->flags & UNIT_ATT))                          /* attached? */
      return SCPE_OK;
  tmxr_close_master (mp);                                 /* close master socket */
  free (uptr->filename);                                  /* free port string */
  uptr->filename = NULL;
  uptr->flags = uptr->flags & ~UNIT_ATT;                  /* not attached */
  return SCPE_OK;
  }
  
  /* Stub examine and deposit */
  
  t_stat tmxr_ex (t_value *vptr, t_addr addr, UNIT *uptr, int32 sw)
  {
  return SCPE_NOFNC;
  }
  
  t_stat tmxr_dep (t_value val, t_addr addr, UNIT *uptr, int32 sw)
  {
  return SCPE_NOFNC;
  }
  
  /* Output message to socket or line descriptor */
  
  void tmxr_msg (SOCKET sock, char *msg)
  {
  if (sock)
      sim_write_sock (sock, msg, strlen (msg));
  return;
  }
  
  void tmxr_linemsg (TMLN *lp, char *msg)
  {
  int32 len;
  
  for (len = strlen (msg); len > 0; --len)
      tmxr_putc_ln (lp, *msg++);
  return;
  }
  
  /* Print connections - used only in named SHOW command */
  
  void tmxr_fconns (FILE *st, TMLN *lp, int32 ln)
  {
  if (ln >= 0)
      fprintf (st, "line %d: ", ln);
  if (lp->conn) {
      int32 o1, o2, o3, o4, hr, mn, sc;
      uint32 ctime;
  
      o1 = (lp->ipad >> 24) & 0xFF;
      o2 = (lp->ipad >> 16) & 0xFF;
      o3 = (lp->ipad >> 8) & 0xFF;
      o4 = (lp->ipad) & 0xFF;
      ctime = (sim_os_msec () - lp->cnms) / 1000;
      hr = ctime / 3600;
      mn = (ctime / 60) % 60;
      sc = ctime % 60;
      fprintf (st, "IP address %d.%d.%d.%d", o1, o2, o3, o4);
      if (ctime)
          fprintf (st, ", connected %02d:%02d:%02d\n", hr, mn, sc);
      }
  else fprintf (st, "line disconnected\n");
  if (lp->txlog)
      fprintf (st, "Logging to %s\n", lp->txlogname);
  return;
  }
  
  /* Print statistics - used only in named SHOW command */
  
  void tmxr_fstats (FILE *st, TMLN *lp, int32 ln)
  {
  static const char *enab = "on";
  static const char *dsab = "off";
  
  if (ln >= 0)
      fprintf (st, "line %d: ", ln);
  if (lp->conn) {
      fprintf (st, "input (%s) queued/total = %d/%d, ",
          (lp->rcve? enab: dsab),
          lp->rxbpi - lp->rxbpr, lp->rxcnt);
      fprintf (st, "output (%s) queued/total = %d/%d\n",
          (lp->xmte? enab: dsab),
          lp->txbpi - lp->txbpr, lp->txcnt);
      }
  else fprintf (st, "line disconnected\n");
  return;
  }
  
  /* Disconnect line */
  
  t_stat tmxr_dscln (UNIT *uptr, int32 val, char *cptr, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  TMLN *lp;
  int32 ln;
  t_stat r;
  
  if (mp == NULL)
      return SCPE_IERR;
  if (val) {                                              /* = n form */
      if (cptr == NULL)
          return SCPE_ARG;
      ln = (int32) get_uint (cptr, 10, mp->lines - 1, &r);
      if (r != SCPE_OK)
          return SCPE_ARG;
      lp = mp->ldsc + ln;
      }
  else {
      lp = tmxr_find_ldsc (uptr, 0, mp);
      if (lp == NULL)
          return SCPE_IERR;
      }
  if (lp->conn) {
      tmxr_linemsg (lp, "\r\nOperator disconnected line\r\n\n");
      tmxr_reset_ln (lp);
      }
  return SCPE_OK;
  }
  
  /* Enable logging for line */
  
  t_stat tmxr_set_log (UNIT *uptr, int32 val, char *cptr, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  TMLN *lp;
  
  if (cptr == NULL)                                       /* no file name? */
      return SCPE_2FARG;
  lp = tmxr_find_ldsc (uptr, val, mp);                    /* find line desc */
  if (lp == NULL)
      return SCPE_IERR;
  if (lp->txlog)                                          /* close existing log */
      tmxr_set_nolog (NULL, val, NULL, desc);
  lp->txlogname = (char *) calloc (CBUFSIZE, sizeof (char)); /* alloc namebuf */
  if (lp->txlogname == NULL)                              /* can't? */
      return SCPE_MEM;
  strncpy (lp->txlogname, cptr, CBUFSIZE);                /* save file name */
  lp->txlog = fopen (cptr, "ab");                         /* open log */
  if (lp->txlog == NULL) {                                /* error? */
      free (lp->txlogname);                               /* free buffer */
      return SCPE_OPENERR;
      }
  return SCPE_OK;
  }
  
  /* Disable logging for line */
  
  t_stat tmxr_set_nolog (UNIT *uptr, int32 val, char *cptr, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  TMLN *lp;
  
  if (cptr)                                               /* no arguments */
      return SCPE_2MARG;
  lp = tmxr_find_ldsc (uptr, val, mp);                    /* find line desc */
  if (lp == NULL)
      return SCPE_IERR;
  if (lp->txlog) {                                        /* logging? */
      fclose (lp->txlog);                                 /* close log */
      free (lp->txlogname);                               /* free namebuf */
      lp->txlog = NULL;
      lp->txlogname = NULL;
      }
  return SCPE_OK;
  }
  
  /* Show logging status for line */
  
  t_stat tmxr_show_log (FILE *st, UNIT *uptr, int32 val, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  TMLN *lp;
  
  lp = tmxr_find_ldsc (uptr, val, mp);                    /* find line desc */
  if (lp == NULL)
      return SCPE_IERR;
  if (lp->txlog)
      fprintf (st, "logging to %s", lp->txlogname);
  else fprintf (st, "no logging");
  return SCPE_OK;
  }
  
  /* Find line descriptor.
  
     Note: This routine may be called with a UNIT that does not belong to the
     device indicated in the TMXR structure.  That is, the multiplexer lines may
     belong to a device other than the one attached to the socket (the HP 2100 MUX
     device is one example).  Therefore, we must look up the device from the unit
     at each call, rather than depending on the DPTR stored in the TMXR.
  */
  
  TMLN *tmxr_find_ldsc (UNIT *uptr, int32 val, TMXR *mp)
  {
  if (uptr) {                                             /* called from SET? */
      DEVICE *dptr = find_dev_from_unit (uptr);           /* find device */
      if (dptr == NULL)                                   /* what?? */
          return NULL;
      val = (int32) (uptr - dptr->units);                 /* implicit line # */
      }
  if ((val < 0) || (val >= mp->lines))                    /* invalid line? */
      return NULL;
  return mp->ldsc + val;                                  /* line descriptor */
  }
  
  /* Set the line connection order.
  
     Example command for eight-line multiplexer:
  
        SET <dev> LINEORDER=1;5;2-4;7
  
     Resulting connection order: 1,5,2,3,4,7,0,6.
  
     Parameters:
      - uptr = (not used)
      - val  = (not used)
      - cptr = pointer to first character of range specification
      - desc = pointer to multiplexer's TMXR structure
  
     On entry, cptr points to the value portion of the command string, which may
     be either a semicolon-separated list of line ranges or the keyword ALL.
  
     If a line connection order array is not defined in the multiplexer
     descriptor, the command is rejected.  If the specified range encompasses all
     of the lines, the first value of the connection order array is set to -1 to
     indicate sequential connection order.  Otherwise, the line values in the
     array are set to the order specified by the command string.  All values are
     populated, first with those explicitly specified in the command string, and
     then in ascending sequence with those not specified.
  
     If an error occurs, the original line order is not disturbed.
  */
  
  t_stat tmxr_set_lnorder (UNIT *uptr, int32 val, char *cptr, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  char *tptr;
  t_addr low, high, max = (t_addr) mp->lines - 1;
  int32 *list;
  t_bool *set;
  uint32 line, idx = 0;
  t_stat result = SCPE_OK;
  
  if (mp->lnorder == NULL)                                /* line connection order undefined? */
      return SCPE_NXPAR;                                  /* "Non-existent parameter" error */
  
  else if ((cptr == NULL) || (*cptr == '\0'))             /* line range not supplied? */
      return SCPE_MISVAL;                                 /* "Missing value" error */
  
  list = (int32 *) calloc (mp->lines, sizeof (int32));    /* allocate new line order array */
  
  if (list == NULL)                                       /* allocation failed? */
      return SCPE_MEM;                                    /* report it */
  
  set = (t_bool *) calloc (mp->lines, sizeof (t_bool));   /* allocate line set tracking array */
  
  if (set == NULL) {                                      /* allocation failed? */
      free (list);                                        /* free successful list allocation */
      return SCPE_MEM;                                    /* report it */
      }
  
  tptr = cptr + strlen (cptr);                            /* append a semicolon */
  *tptr++ = ';';                                          /*   to the command string */
  *tptr = '\0';                                           /*   to make parsing easier for get_range */
  
  while (*cptr) {                                                 /* parse command string */
      cptr = get_range (NULL, cptr, &low, &high, 10, max, ';');   /* get a line range */
  
      if (cptr == NULL) {                                 /* parsing error? */
          result = SCPE_ARG;                              /* "Invalid argument" error */
          break;
          }
  
      else if ((low > max) || (high > max)) {             /* line out of range? */
          result = SCPE_SUB;                              /* "Subscript out of range" error */
          break;
          }
  
      else if ((low == 0) && (high == max)) {             /* entire line range specified? */
          list [0] = -1;                                  /* set sequential order flag */
          idx = (uint32) max + 1;                         /* indicate no fill-in needed */
          break;
          }
  
      else
          for (line = (uint32) low; line <= (uint32) high; line++) /* see if previously specified */
              if (set [line] == FALSE) {                  /* not already specified? */
                  set [line] = TRUE;                      /* now it is */
                  list [idx] = line;                      /* add line to connection order */
                  idx = idx + 1;                          /* bump "specified" count */
                  }
      }
  
  if (result == SCPE_OK) {                                /* assignment successful? */
      if (idx <= max)                                     /* any lines not specified? */
          for (line = 0; line <= max; line++)             /* fill them in sequentially */
              if (set [line] == FALSE) {                  /* specified? */
                  list [idx] = line;                      /* no, so add it */
                  idx = idx + 1;
                  }
  
      memcpy (mp->lnorder, list, mp->lines * sizeof (int32)); /* copy working array to connection array */
      }
  
  free (list);                                            /* free list allocation */
  free (set);                                             /* free set allocation */
  
  return result;
  }
  
  /* Show line connection order.
  
     Parameters:
      - st   = stream on which output is to be written
      - uptr = (not used)
      - val  = (not used)
      - desc = pointer to multiplexer's TMXR structure
  
     If a connection order array is not defined in the multiplexer descriptor, the
     command is rejected.  If the first value of the connection order array is set
     to -1, then the connection order is sequential.  Otherwise, the line values
     in the array are printed as a semicolon-separated list.  Ranges are printed
     where possible to shorten the output.
  */
  
  t_stat tmxr_show_lnorder (FILE *st, UNIT *uptr, int32 val, void *desc)
  {
  int32 i, j, low, last;
  TMXR *mp = (TMXR *) desc;
  int32 *iptr = mp->lnorder;
  t_bool first = TRUE;
  
  if (iptr == NULL)                                       /* connection order undefined? */
      return SCPE_NXPAR;                                  /* "Non-existent parameter" error */
  
  if (*iptr < 0)                                          /* sequential order indicated? */
      fprintf (st, "Order=0-%d\n", mp->lines - 1);        /* print full line range */
  
  else {
      low = last = *iptr++;                               /* set first line value */
  
      for (j = 1; j <= mp->lines; j++) {                  /* print remaining lines in order list */
          if (j < mp->lines)                              /* more lines to process? */
              i = *iptr++;                                /* get next line in list */
          else                                            /* final iteration */
              i = -1;                                     /* get "tie-off" value */
  
          if (i != last + 1) {                            /* end of a range? */
              if (first) {                                /* first line to print? */
                  fputs ("Order=", st);                   /* print header */
                  first = FALSE;
                  }
  
              else                                        /* not first line printed */
                  fputc (';', st);                        /* print separator */
  
              if (low == last)                            /* range null? */
                  fprintf (st, "%d", last);               /* print single line value */
  
              else                                        /* range established */
                  fprintf (st, "%d-%d", low, last);       /* print start and end line */
  
              low = i;                                    /* start new range */
              }
  
          last = i;                                       /* note value for range check */
          }
      }
  
  if (first == FALSE)                                     /* sanity check for lines == 0 */
      fputc ('\n', st);
  
  return SCPE_OK;
  }
  
  /* Show summary processor */
  
  t_stat tmxr_show_summ (FILE *st, UNIT *uptr, int32 val, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  int32 i, t;
  
  if (mp == NULL)
      return SCPE_IERR;
  for (i = t = 0; i < mp->lines; i++)
      t = t + (mp->ldsc[i].conn != 0);
  if (t == 1)
      fprintf (st, "1 connection");
  else fprintf (st, "%d connections", t);
  return SCPE_OK;
  }
  
  /* Show conn/stat processor */
  
  t_stat tmxr_show_cstat (FILE *st, UNIT *uptr, int32 val, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  int32 i, any;
  
  if (mp == NULL)
      return SCPE_IERR;
  for (i = any = 0; i < mp->lines; i++) {
      if (mp->ldsc[i].conn) {
          any++;
          if (val)
              tmxr_fconns (st, &mp->ldsc[i], i);
          else tmxr_fstats (st, &mp->ldsc[i], i);
          }
      }
  if (any == 0)
      fprintf (st, (mp->lines == 1? "disconnected\n": "all disconnected\n"));
  return SCPE_OK;
  }
  
  /* Show number of lines */
  
  t_stat tmxr_show_lines (FILE *st, UNIT *uptr, int32 val, void *desc)
  {
  TMXR *mp = (TMXR *) desc;
  
  if (mp == NULL)
      return SCPE_IERR;
  fprintf (st, "lines=%d", mp->lines);
  return SCPE_OK;
  }
  
  