[unix-history] / gnu / libexec / uucp / uucico / trans.c

/* trans.c
  Routines to handle file transfers.

  Copyright (C) 1992 Ian Lance Taylor

  This file is part of the Taylor UUCP package.

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

  The author of the program may be contacted at ian@airs.com or
  c/o Infinity Development Systems, P.O. Box 520, Waltham, MA 02254.
  */

#include "uucp.h"

#if USE_RCS_ID
const char trans_rcsid[] = "$Id: trans.c,v 1.1 1993/08/04 19:36:31 jtc Exp $";
#endif

#include <errno.h>

#include "uudefs.h"
#include "uuconf.h"
#include "prot.h"
#include "system.h"
#include "trans.h"
\f
/* Local functions.  */

static void utqueue P((struct stransfer **, struct stransfer *,
                      boolean fhead));
static void utdequeue P((struct stransfer *));
static void utchanalc P((struct sdaemon *qdaemon, struct stransfer *qtrans));
__inline__ static struct stransfer *qtchan P((int ichan));
__inline__ static void utchanfree P((struct stransfer *qtrans));
static boolean ftcharge P((struct sdaemon *qdaemon,
                          struct stransfer *qtrans,
                          boolean fsend, boolean fforce));
static boolean fcheck_queue P((struct sdaemon *qdaemon));
static boolean ftadd_cmd P((struct sdaemon *qdaemon, const char *z,
                           size_t cdata, int iremote, boolean flast));
static boolean fremote_hangup_reply P((struct stransfer *qtrans,
                                      struct sdaemon *qdaemon));
static boolean flocal_poll_file P((struct stransfer *qtrans,
                                  struct sdaemon *qdaemon));
\f
/* Queue of transfer structures that are ready to start which have
  been requested by the local system.  These are only permitted to
  start when the local system is the master.  */
static struct stransfer *qTlocal;

/* Queue of transfer structures that are ready to start which have
  been requested by the remote system.  These are responses to
  commands received from the remote system, and should be started as
  soon as possible.  */
static struct stransfer *qTremote;

/* Queue of transfer structures that have been started and want to
  send information.  This should be static, but the 'a' protocol
  looks at it, at least for now.  */
struct stransfer *qTsend;

/* Queue of transfer structures that have been started and are waiting
  to receive information.  */
static struct stransfer *qTreceive;

/* Queue of free transfer structures.  */
static struct stransfer *qTavail;

/* Array of transfer structures indexed by local channel number.  This
  is maintained for local jobs.  */
static struct stransfer *aqTchan[IMAX_CHAN + 1];

/* Number of local channel numbers currently allocated.  */
static int cTchans;

/* Next channel number to allocate.  */
static int iTchan;

/* Array of transfer structures indexed by remote channel number.
  This is maintained for remote jobs.  */
static struct stransfer *aqTremote[IMAX_CHAN + 1];

/* A structure used to charge time to file transfers.  */
struct scharge
{
 /* The transfer we are currently charging.  */
 struct stransfer *qtrans;
 /* The time at the last update.  */
 long isecs;
 long imicros;
};

/* We are always charging one send and one receive.  */
static struct scharge sTsend;
static struct scharge sTreceive;

/* The minimum amount of time, in seconds, to wait between times we
  check the spool directory, if we are busy transferring data.  If we
  have nothing to do, we will check the spool directory regardless of
  how long ago the last check was.  This should probably be
  configurable.  */
#define CCHECKWAIT (600)

/* The time we last checked the spool directory for work.  This is set
  from the return value of ixsysdep_process_time, not ixsysdep_time,
  for convenience in the routines which use it.  */
static long iTchecktime;

/* The size of the command we have read so far in ftadd_cmd.  */
static size_t cTcmdlen;

/* The structure we use when waiting for an acknowledgement of a
  confirmed received file in fsent_receive_ack, and a list of those
  structures.  */

struct sreceive_ack
{
 struct sreceive_ack *qnext;
 char *zto;
 char *ztemp;
 boolean fmarked;
};

static struct sreceive_ack *qTreceive_ack;
\f
/* Queue up a transfer structure before *pq.  This puts it at the head
  or the tail of the list headed by *pq.  */

static void
utqueue (pq, q, fhead)
    struct stransfer **pq;
    struct stransfer *q;
    boolean fhead;
{
 if (*pq == NULL)
   {
     *pq = q;
     q->qprev = q->qnext = q;
   }
 else
   {
     q->qnext = *pq;
     q->qprev = (*pq)->qprev;
     q->qprev->qnext = q;
     q->qnext->qprev = q;
     if (fhead)
       *pq = q;
   }
 q->pqqueue = pq;
}

/* Dequeue a transfer structure.  */

static void
utdequeue (q)
    struct stransfer *q;
{
 if (q->pqqueue != NULL)
   {
     if (*(q->pqqueue) == q)
       {
         if (q->qnext == q)
           *(q->pqqueue) = NULL;
         else
           *(q->pqqueue) = q->qnext;
       }
     q->pqqueue = NULL;
   }
 if (q->qprev != NULL)
   q->qprev->qnext = q->qnext;
 if (q->qnext != NULL)
   q->qnext->qprev = q->qprev;
 q->qprev = NULL;
 q->qnext = NULL;
}
\f
/* Queue up a transfer structure requested by the local system.  */

/*ARGSIGNORED*/
boolean
fqueue_local (qdaemon, qtrans)
    struct sdaemon *qdaemon;
    struct stransfer *qtrans;
{
 utdequeue (qtrans);
 utqueue (&qTlocal, qtrans, FALSE);
 return TRUE;
}

/* Queue up a transfer structure requested by the remote system.  The
  stransfer structure should have the iremote field set.  We need to
  record it, so that any subsequent data associated with this
  channel can be routed to the right place.  */

boolean
fqueue_remote (qdaemon, qtrans)
    struct sdaemon *qdaemon;
    struct stransfer *qtrans;
{
 DEBUG_MESSAGE1 (DEBUG_UUCP_PROTO, "fqueue_remote: Channel %d",
                 qtrans->iremote);
 if (qtrans->iremote > 0)
   aqTremote[qtrans->iremote] = qtrans;
 utdequeue (qtrans);
 utqueue (&qTremote, qtrans, FALSE);

 /* We just received data for this transfer, so start charging.  */
 return ftcharge (qdaemon, qtrans, FALSE, FALSE);
}

/* Queue up a transfer with something to send.  */

boolean
fqueue_send (qdaemon, qtrans)
    struct sdaemon *qdaemon;
    struct stransfer *qtrans;
{
#if DEBUG > 0
 if (qtrans->psendfn == NULL)
   ulog (LOG_FATAL, "fqueue_send: Bad call");
#endif
 utdequeue (qtrans);
 utqueue (&qTsend, qtrans, FALSE);

 /* Since we're now going to wait to send data, don't charge this
    transfer for receive time.  */
 if (qtrans == sTreceive.qtrans)
   return ftcharge (qdaemon, (struct stransfer *) NULL, FALSE, FALSE);
 return TRUE;
}

/* Queue up a transfer with something to receive.  */

boolean
fqueue_receive (qdaemon, qtrans)
    struct sdaemon *qdaemon;
    struct stransfer *qtrans;
{
#if DEBUG > 0
 if (qtrans->precfn == NULL)
   ulog (LOG_FATAL, "fqueue_receive: Bad call");
#endif
 utdequeue (qtrans);
 utqueue (&qTreceive, qtrans, FALSE);

 /* Since we are now going to wait to receive data, don't charge this
    transfer for send time.  */
 if (qtrans == sTsend.qtrans)
   return ftcharge (qdaemon, (struct stransfer *) NULL, TRUE, FALSE);
 return TRUE;
}
\f
/* Get a new local channel number.  */

static void
utchanalc (qdaemon, qtrans)
    struct sdaemon *qdaemon;
    struct stransfer *qtrans;
{
 do
   {
     ++iTchan;
     if (iTchan > qdaemon->qproto->cchans)
       iTchan = 1;
   }
 while (aqTchan[iTchan] != NULL);

 qtrans->ilocal = iTchan;
 aqTchan[iTchan] = qtrans;
 ++cTchans;
}

/* Return the transfer for a channel number.  */

__inline__
static struct stransfer *
qtchan (ic)
    int ic;
{
 return aqTchan[ic];
}

/* Clear the channel number for a transfer.  */

__inline__
static void
utchanfree (qt)
    struct stransfer *qt;
{
 if (qt->ilocal != 0)
   {
     aqTchan[qt->ilocal] = NULL;
     qt->ilocal = 0;
     --cTchans;
   }
}
\f
/* Allocate a new transfer structure.  */

struct stransfer *
qtransalc (qcmd)
    struct scmd *qcmd;
{
 register struct stransfer *q;

 q = qTavail;
 if (q != NULL)
   utdequeue (q);
 else
   q = (struct stransfer *) xmalloc (sizeof (struct stransfer));
 q->qnext = NULL;
 q->qprev = NULL;
 q->pqqueue = NULL;
 q->psendfn = NULL;
 q->precfn = NULL;
 q->pinfo = NULL;
 q->fsendfile = FALSE;
 q->frecfile = FALSE;
 q->e = EFILECLOSED;
 q->ipos = 0;
 q->fcmd = FALSE;
 q->zcmd = NULL;
 q->ccmd = 0;
 q->ilocal = 0;
 q->iremote = 0;
 if (qcmd != NULL)
   {
     q->s = *qcmd;
     q->s.zfrom = zbufcpy (qcmd->zfrom);
     q->s.zto = zbufcpy (qcmd->zto);
     q->s.zuser = zbufcpy (qcmd->zuser);
     q->s.zoptions = zbufcpy (qcmd->zoptions);
     q->s.ztemp = zbufcpy (qcmd->ztemp);
     q->s.znotify = zbufcpy (qcmd->znotify);
     q->s.zcmd = zbufcpy (qcmd->zcmd);
   }
 else
   {
     q->s.zfrom = NULL;
     q->s.zto = NULL;
     q->s.zuser = NULL;
     q->s.zoptions = NULL;
     q->s.ztemp = NULL;
     q->s.znotify = NULL;
     q->s.zcmd = NULL;
   }
 q->isecs = 0;
 q->imicros = 0;
 q->cbytes = 0;

 return q;
}
\f
/* Free a transfer structure.  This does not free any pinfo
  information that may have been allocated.  */

void
utransfree (q)
    struct stransfer *q;
{
 ubuffree (q->zcmd);
 ubuffree ((char *) q->s.zfrom);
 ubuffree ((char *) q->s.zto);
 ubuffree ((char *) q->s.zuser);
 ubuffree ((char *) q->s.zoptions);
 ubuffree ((char *) q->s.ztemp);
 ubuffree ((char *) q->s.znotify);
 ubuffree ((char *) q->s.zcmd);
 
 utchanfree (q);    
 if (q->iremote > 0)
   {
     aqTremote[q->iremote] = NULL;
     q->iremote = 0;
   }

#if DEBUG > 0
 q->zcmd = NULL;
 q->s.zfrom = NULL;
 q->s.zto = NULL;
 q->s.zuser = NULL;
 q->s.zoptions = NULL;
 q->s.ztemp = NULL;
 q->s.znotify = NULL;
 q->s.zcmd = NULL;
 q->psendfn = NULL;
 q->precfn = NULL;
#endif

 /* Don't try to charge time to this structure any longer.  */
 if (sTsend.qtrans == q)
   sTsend.qtrans = NULL;
 if (sTreceive.qtrans == q)
   sTreceive.qtrans = NULL;

 utdequeue (q);
 utqueue (&qTavail, q, FALSE);
}
\f
/* Handle timing of file tranfers.  This is called when processing
  starts for a transfer structure.  All time up to the next call to
  this function is charged to that transfer structure.  Sending time
  and receiving time are charged separately.  Normally if we are
  about to start charging the same structure we are already charging,
  we do nothing; but if the fforce argument is TRUE, we charge the
  time anyhow.  */

static boolean
ftcharge (qdaemon, qtrans, fsend, fforce)
    struct sdaemon *qdaemon;
    struct stransfer *qtrans;
    boolean fsend;
    boolean fforce;
{
 struct scharge *qcharge, *qother;
 long inextsecs, inextmicros;

 if (fsend)
   {
     qcharge = &sTsend;
     qother = &sTreceive;
   }
 else
   {
     qcharge = &sTreceive;
     qother = &sTsend;
   }

 if (! fforce && qtrans == qcharge->qtrans)
   return TRUE;

 inextsecs = ixsysdep_process_time (&inextmicros);
 if (qcharge->qtrans != NULL)
   {
     qcharge->qtrans->isecs += inextsecs - qcharge->isecs;
     qcharge->qtrans->imicros += inextmicros - qcharge->imicros;

     /* If we are charging the same structure for both send and
        receive, update the time we are not currently charging so
        that we don't charge twice for the same time.  */
     if (qcharge->qtrans == qother->qtrans)
       {
         qother->isecs = inextsecs;
         qother->imicros = inextmicros;
       }         
   }
 
 qcharge->qtrans = qtrans;
 qcharge->isecs = inextsecs;
 qcharge->imicros = inextmicros;

 /* If enough time has elapsed since the last time we checked the
    queue, check it again.  We do this here because we have already
    gone to the trouble of getting the time.  */
 if (inextsecs - iTchecktime >= CCHECKWAIT)
   {
     if (! fcheck_queue (qdaemon))
       return FALSE;
   }

 return TRUE;
}

\f
/* Gather local commands and queue them up for later processing.  Also
  recompute time based control values.  */

boolean
fqueue (qdaemon, pfany)
    struct sdaemon *qdaemon;
    boolean *pfany;
{
 const struct uuconf_system *qsys;
 int bgrade;
 struct uuconf_timespan *qlocal_size, *qremote_size;

 if (pfany != NULL)
   *pfany = FALSE;

 qsys = qdaemon->qsys;

 /* If we are not the caller, the grade will be set during the
    initial handshake.  */
 if (! qdaemon->fcaller)
   bgrade = qdaemon->bgrade;
 else
   {
     long ival;

     if (! ftimespan_match (qsys->uuconf_qtimegrade, &ival,
                            (int *) NULL))
       bgrade = '\0';
     else
       bgrade = (char) ival;
   }

 /* Determine the maximum sizes we can send and receive.  */
 if (qdaemon->fcaller)
   {
     qlocal_size = qsys->uuconf_qcall_local_size;
     qremote_size = qsys->uuconf_qcall_remote_size;
   }
 else
   {
     qlocal_size = qsys->uuconf_qcalled_local_size;
     qremote_size = qsys->uuconf_qcalled_remote_size;
   }

 if (! ftimespan_match (qlocal_size, &qdaemon->clocal_size, (int *) NULL))
   qdaemon->clocal_size = (long) -1;
 if (! ftimespan_match (qremote_size, &qdaemon->cremote_size, (int *) NULL))
   qdaemon->cremote_size = (long) -1;

 if (bgrade == '\0')
   return TRUE;

 if (! fsysdep_get_work_init (qsys, bgrade))
   return FALSE;

 while (TRUE)
   {
     struct scmd s;

     if (! fsysdep_get_work (qsys, bgrade, &s))
       return FALSE;

     if (s.bcmd == 'H')
       {
         ulog_user ((const char *) NULL);
         break;
       }

     if (s.bcmd == 'P')
       {
         struct stransfer *qtrans;

         /* A poll file.  */
         ulog_user ((const char *) NULL);
         qtrans = qtransalc (&s);
         qtrans->psendfn = flocal_poll_file;
         if (! fqueue_local (qdaemon, qtrans))
           return FALSE;
         continue;
       }

     ulog_user (s.zuser);

     switch (s.bcmd)
       {
       case 'S':
       case 'E':
         if (! flocal_send_file_init (qdaemon, &s))
           return FALSE;
         break;
       case 'R':
         if (! flocal_rec_file_init (qdaemon, &s))
           return FALSE;
         break;
       case 'X':
         if (! flocal_xcmd_init (qdaemon, &s))
           return FALSE;
         break;
#if DEBUG > 0
       default:
         ulog (LOG_FATAL, "fqueue: Can't happen");
         break;
#endif
       }
   }     

 if (pfany != NULL)
   *pfany = qTlocal != NULL;

 iTchecktime = ixsysdep_process_time ((long *) NULL);

 return TRUE;
}

/* Clear everything off the work queue.  This is used when the call is
  complete, or if the call is never made.  */

void
uclear_queue (qdaemon)
    struct sdaemon *qdaemon;
{
 int i;

 usysdep_get_work_free (qdaemon->qsys);

 qTlocal = NULL;
 qTremote = NULL;
 qTsend = NULL;
 qTreceive = NULL;
 cTchans = 0;
 iTchan = 0;
 sTsend.qtrans = NULL;
 sTreceive.qtrans = NULL;
 cTcmdlen = 0;
 qTreceive_ack = NULL;
 for (i = 0; i < IMAX_CHAN + 1; i++)
   {
     aqTchan[i] = NULL;
     aqTremote[i] = NULL;
   }
}

/* Recheck the work queue during a conversation.  This is only called
  if it's been more than CCHECKWAIT seconds since the last time the
  queue was checked.  */

static boolean
fcheck_queue (qdaemon)
    struct sdaemon *qdaemon;
{
 int cchans;

 /* Only check if we are the master, or if there are multiple
    channels, or if we aren't already trying to get the other side to
    hang up.  Otherwise, there's nothing we can do with any new jobs
    we might find.  */
 if ((qdaemon->ireliable & UUCONF_RELIABLE_FULLDUPLEX) == 0)
   cchans = 1;
 else
   cchans = qdaemon->qproto->cchans;
 if (qdaemon->fmaster
     || cchans > 1
     || ! qdaemon->frequest_hangup)
   {
     boolean fany;

     DEBUG_MESSAGE0 (DEBUG_UUCP_PROTO,
                     "fcheck_queue: Rechecking work queue");
     if (! fqueue (qdaemon, &fany))
       return FALSE;

     /* If we found something to do, and we're not the master, and we
        don't have multiple channels to send new jobs over, try to
        get the other side to hang up.  */
     if (fany && ! qdaemon->fmaster && cchans <= 1)
       qdaemon->frequest_hangup = TRUE;
   }

 return TRUE;
}
\f
/* The main transfer loop.  The uucico daemon spends essentially all
  its time in this function.  */

boolean
floop (qdaemon)
    struct sdaemon *qdaemon;
{
 int cchans;
 boolean fret;

 /* If we are using a half-duplex line, act as though we have only a
    single channel; otherwise we might start a send and a receive at
    the same time.  */
 if ((qdaemon->ireliable & UUCONF_RELIABLE_FULLDUPLEX) == 0)
   cchans = 1;
 else
   cchans = qdaemon->qproto->cchans;

 fret = TRUE;

 while (! qdaemon->fhangup)
   {
     register struct stransfer *q;

#if DEBUG > 1
     /* If we're doing any debugging, close the log and debugging
        files regularly.  This will let people copy them off and
        remove them while the conversation is in progresss.  */
     if (iDebug != 0)
       {
         ulog_close ();
         ustats_close ();
       }
#endif

     if (qdaemon->fmaster)
       {
         boolean fhangup;

         /* We've managed to become the master, so we no longer want
            to request a hangup.  */
         qdaemon->frequest_hangup = FALSE;

         fhangup = FALSE;

         if (qdaemon->fhangup_requested
             && qTsend == NULL)
           {
             /* The remote system has requested that we transfer
                control by sending CYM after receiving a file.  */
             DEBUG_MESSAGE0 (DEBUG_UUCP_PROTO,
                             "floop: Transferring control at remote request");
             fhangup = TRUE;
           }
         else if (qTremote == NULL
                  && qTlocal == NULL
                  && qTsend == NULL
                  && qTreceive == NULL)
           {
             /* We don't have anything to do.  Try to find some new
                jobs.  If we can't, transfer control.  */
             if (! fqueue (qdaemon, (boolean *) NULL))
               {
                 fret = FALSE;
                 break;
               }
             if (qTlocal == NULL)
               {
                 DEBUG_MESSAGE0 (DEBUG_UUCP_PROTO,
                                 "floop: No work for master");
                 fhangup = TRUE;
               }
           }

         if (fhangup)
           {
             if (! (*qdaemon->qproto->pfsendcmd) (qdaemon, "H", 0, 0))
               {
                 fret = FALSE;
                 break;
               }
             qdaemon->fmaster = FALSE;
           }
       }

     /* If we are no long the master, clear any requested hangup.  We
        may have already hung up before checking this variable in the
        block above.  */
     if (! qdaemon->fmaster)
       qdaemon->fhangup_requested = FALSE;

     /* Immediately queue up any remote jobs.  We don't need local
        channel numbers for them, since we can disambiguate based on
        the remote channel number.  */
     while (qTremote != NULL)
       {
         q = qTremote;
         utdequeue (q);
         utqueue (&qTsend, q, TRUE);
       }

     /* If we are the master, or if we have multiple channels, try to
        queue up additional local jobs.  */
     if (qdaemon->fmaster || cchans > 1)
       {
         while (qTlocal != NULL && cTchans < cchans)
           {
             /* We have room for an additional channel.  */
             q = qTlocal;
             if (! fqueue_send (qdaemon, q))
               {
                 fret = FALSE;
                 break;
               }
             utchanalc (qdaemon, q);
           }
         if (! fret)
           break;
       }

     q = qTsend;

     if (q == NULL)
       {
         ulog_user ((const char *) NULL);
         DEBUG_MESSAGE0 (DEBUG_UUCP_PROTO, "floop: Waiting for data");
         if (! (*qdaemon->qproto->pfwait) (qdaemon))
           {
             fret = FALSE;
             break;
           }
       }
     else
       {
         ulog_user (q->s.zuser);

         if (! q->fsendfile)
           {
             if (! ftcharge (qdaemon, q, TRUE, TRUE))
               {
                 fret = FALSE;
                 break;
               }

             if (! (*q->psendfn) (q, qdaemon))
               {
                 fret = FALSE;
                 break;
               }
           }
         else
           {
             if (! ftcharge (qdaemon, q, TRUE, FALSE))
               {
                 fret = FALSE;
                 break;
               }

             if (q->zlog != NULL)
               {
                 ulog (LOG_NORMAL, "%s", q->zlog);
                 ubuffree (q->zlog);
                 q->zlog = NULL;
               }

             /* We can read the file in a tight loop until qTremote
                changes or until we have transferred the entire file.
                We can disregard any changes to qTlocal since we
                already have something to send anyhow.  */
             while (qTremote == NULL)
               {
                 char *zdata;
                 size_t cdata;
                 long ipos;

                 zdata = (*qdaemon->qproto->pzgetspace) (qdaemon, &cdata);
                 if (zdata == NULL)
                   {
                     fret = FALSE;
                     break;
                   }

                 if (ffileeof (q->e))
                   cdata = 0;
                 else
                   {
                     cdata = cfileread (q->e, zdata, cdata);
                     if (ffilereaderror (q->e, cdata))
                       {
                         /* There is no way to report a file reading
                            error, so we just drop the connection.  */
                         ulog (LOG_ERROR, "read: %s", strerror (errno));
                         fret = FALSE;
                         break;
                       }
                   }

                 ipos = q->ipos;
                 q->ipos += cdata;
                 q->cbytes += cdata;

                 if (! (*qdaemon->qproto->pfsenddata) (qdaemon, zdata,
                                                       cdata, q->ilocal,
                                                       q->iremote, ipos))
                   {
                     fret = FALSE;
                     break;
                   }

                 /* It is possible that this transfer has just been
                    cancelled.  */
                 if (q != qTsend || ! q->fsendfile)
                   break;

                 if (cdata == 0)
                   {
                     /* We must update the time now, because this
                        call may make an entry in the statistics
                        file.  */
                     if (! ftcharge (qdaemon, q, TRUE, TRUE))
                       fret = FALSE;
                     q->fsendfile = FALSE;
                     if (! (*q->psendfn) (q, qdaemon))
                       fret = FALSE;
                     break;
                   }
               }

             if (! fret)
               break;
           }
       }
   }

 ulog_user ((const char *) NULL);

 (void) (*qdaemon->qproto->pfshutdown) (qdaemon);

 if (fret)
   uwindow_acked (qdaemon, TRUE);
 else
   ufailed (qdaemon);

 return fret;
}
\f
/* This is called by the protocol routines when they have received
  some data.  If pfexit is not NULL, *pfexit should be set to TRUE if
  the protocol receive loop should exit back to the main floop
  routine, above.  It is only important to set *pfexit to TRUE if the
  main loop called the pfwait entry point, so we need never set it to
  TRUE if we just receive data for a file.  This routine never sets
  *pfexit to FALSE.  */

boolean 
fgot_data (qdaemon, zfirst, cfirst, zsecond, csecond, ilocal, iremote, ipos,
          fallacked, pfexit)
    struct sdaemon *qdaemon;
    const char *zfirst;
    size_t cfirst;
    const char *zsecond;
    size_t csecond;
    int ilocal;
    int iremote;
    long ipos;
    boolean fallacked;
    boolean *pfexit;
{
 struct stransfer *q;
 int cwrote;
 boolean fret;

 if (fallacked && qTreceive_ack != NULL)
   uwindow_acked (qdaemon, TRUE);

 /* Now we have to decide which transfer structure gets the data.  If
    ilocal is -1, it means that the protocol does not know where to
    route the data.  In that case we route it to the first transfer
    that is waiting for data, or, if none, as a new command.  If
    ilocal is 0, we either select based on the remote channel number
    or we have a new command.  */
 if (ilocal == -1 && qTreceive != NULL)
   q = qTreceive;
 else if (ilocal == 0 && iremote > 0 && aqTremote[iremote] != NULL)
   q = aqTremote[iremote];
 else if (ilocal <= 0)
   {
     const char *znull;

     ulog_user ((const char *) NULL);

     /* This data is part of a command.  If there is no null
        character in the data, this string will be continued by the
        next packet.  Otherwise this must be the last string in the
        command, and we don't care about what comes after the null
        byte.  */
     znull = (const char *) memchr (zfirst, '\0', cfirst);
     if (znull != NULL)
       fret = ftadd_cmd (qdaemon, zfirst, (size_t) (znull - zfirst),
                         iremote, TRUE);
     else
       {
         fret = ftadd_cmd (qdaemon, zfirst, cfirst, iremote, FALSE);
         if (fret && csecond > 0)
           {
             znull = (const char *) memchr (zsecond, '\0', csecond);
             if (znull != NULL)
               fret = ftadd_cmd (qdaemon, zsecond,
                                 (size_t) (znull - zsecond), iremote, TRUE);
             else
               fret = ftadd_cmd (qdaemon, zsecond, csecond, iremote, FALSE);
           }
       }

     if (pfexit != NULL && (qdaemon->fhangup || qTremote != NULL))
       *pfexit = TRUE;

     return fret;
   }
 else
   {
     /* Get the transfer structure this data is intended for.  */

     q = qtchan (ilocal);
   }

#if DEBUG > 0
 if (q == NULL || q->precfn == NULL)
   {
     ulog (LOG_ERROR, "Protocol error: %lu bytes remote %d local %d",
           (unsigned long) (cfirst + csecond),
           iremote, ilocal);
     return FALSE;
   }
#endif

 ulog_user (q->s.zuser);

 fret = TRUE;

 /* If we're receiving a command, then accumulate it up to the null
    byte.  */
 if (q->fcmd)
   {
     const char *znull;

     znull = NULL;
     while (cfirst > 0)
       {
         size_t cnew;
         char *znew;

         znull = (const char *) memchr (zfirst, '\0', cfirst);
         if (znull != NULL)
           cnew = znull - zfirst;
         else
           cnew = cfirst;
         znew = zbufalc (q->ccmd + cnew + 1);
         memcpy (znew, q->zcmd, q->ccmd);
         memcpy (znew + q->ccmd, zfirst, cnew);
         znew[q->ccmd + cnew] = '\0';
         ubuffree (q->zcmd);
         q->zcmd = znew;
         q->ccmd += cnew;

         if (znull != NULL)
           break;

         zfirst = zsecond;
         cfirst = csecond;
         csecond = 0;
       }

     if (znull != NULL)
       {
         char *zcmd;
         size_t ccmd;

         if (! ftcharge (qdaemon, q, FALSE, TRUE))
           fret = FALSE;
         zcmd = q->zcmd;
         ccmd = q->ccmd;
         q->fcmd = FALSE;
         q->zcmd = NULL;
         q->ccmd = 0;
         if (! (*q->precfn) (q, qdaemon, zcmd, ccmd + 1))
           fret = FALSE;
         ubuffree (zcmd);
       }
     else
       {
         if (! ftcharge (qdaemon, q, FALSE, FALSE))
           fret = FALSE;
       }

     if (pfexit != NULL
         && (qdaemon->fhangup
             || qdaemon->fmaster
             || qTsend != NULL))
       *pfexit = TRUE;
   }
 else if (! q->frecfile || cfirst == 0)
   {
     /* We're either not receiving a file or the file transfer is
        complete.  */
     if (! ftcharge (qdaemon, q, FALSE, TRUE))
       fret = FALSE;
     q->frecfile = FALSE;
     if (! (*q->precfn) (q, qdaemon, zfirst, cfirst))
       fret = FALSE;
     if (fret && csecond > 0)
       return fgot_data (qdaemon, zsecond, csecond,
                         (const char *) NULL, (size_t) 0,
                         ilocal, iremote, ipos + (long) cfirst,
                         FALSE, pfexit);
     if (pfexit != NULL
         && (qdaemon->fhangup
             || qdaemon->fmaster
             || qTsend != NULL))
       *pfexit = TRUE;
   }
 else
   {
     if (! ftcharge (qdaemon, q, FALSE, FALSE))
       fret = FALSE;

     if (q->zlog != NULL)
       {
         ulog (LOG_NORMAL, "%s", q->zlog);
         ubuffree (q->zlog);
         q->zlog = NULL;
       }

     if (ipos != -1 && ipos != q->ipos)
       {
         DEBUG_MESSAGE1 (DEBUG_UUCP_PROTO,
                         "fgot_data: Seeking to %ld", ipos);
         if (! ffileseek (q->e, ipos))
           {
             ulog (LOG_ERROR, "seek: %s", strerror (errno));
             fret = FALSE;
           }
         q->ipos = ipos;
       }

     if (fret)
       {
         while (cfirst > 0)
           {
             cwrote = cfilewrite (q->e, (char *) zfirst, cfirst);
             if (cwrote == cfirst)
               {
#if FREE_SPACE_DELTA > 0
                 long cfree_space;

                 /* Check that there is still enough space on the
                    disk.  If there isn't, we drop the connection,
                    because we have no way to abort a file transfer
                    in progress.  */
                 cfree_space = qdaemon->qsys->uuconf_cfree_space;
                 if (cfree_space > 0
                     && ((q->cbytes / FREE_SPACE_DELTA)
                         != (q->cbytes + cfirst) / FREE_SPACE_DELTA)
                     && ! frec_check_free (q, cfree_space))
                   {
                     fret = FALSE;
                     break;
                   }
#endif
                 q->cbytes += cfirst;
                 q->ipos += cfirst;
               }
             else
               {
                 if (cwrote < 0)
                   ulog (LOG_ERROR, "write: %s", strerror (errno));
                 else
                   ulog (LOG_ERROR,
                         "Wrote %d to file when trying to write %lu",
                         cwrote, (unsigned long) cfirst);

                 /* Any write error is almost certainly a temporary
                    condition, or else UUCP would not be functioning
                    at all.  If we continue to accept the file, we
                    will wind up rejecting it at the end (what else
                    could we do?)  and the remote system will throw
                    away the request.  We're better off just dropping
                    the connection, which is what happens when we
                    return FALSE, and trying again later.  */
                 fret = FALSE;
                 break;
               }

             zfirst = zsecond;
             cfirst = csecond;
             csecond = 0;
           }
       }

     if (pfexit != NULL && qdaemon->fhangup)
       *pfexit = TRUE;
   }

 return fret;
}

/* Accumulate a string into a command.  If the command is complete,
  start up a new transfer.  */

static boolean
ftadd_cmd (qdaemon, z, clen, iremote, flast)
    struct sdaemon *qdaemon;
    const char *z;
    size_t clen;
    int iremote;
    boolean flast;
{
 static char *zbuf;
 static size_t cbuf;
 size_t cneed;
 struct scmd s;

 cneed = cTcmdlen + clen + 1;
 if (cneed > cbuf)
   {
     zbuf = (char *) xrealloc ((pointer) zbuf, cneed);
     cbuf = cneed;
   }

 memcpy (zbuf + cTcmdlen, z, clen);
 zbuf[cTcmdlen + clen] = '\0';

 if (! flast)
   {
     cTcmdlen += clen;
     return TRUE;
   }

 /* Don't save this string for next time.  */
 cTcmdlen = 0;

 DEBUG_MESSAGE1 (DEBUG_UUCP_PROTO,
                 "ftadd_cmd: Got command \"%s\"", zbuf);

 if (! fparse_cmd (zbuf, &s))
   {
     ulog (LOG_ERROR, "Received garbled command \"%s\"", zbuf);
     return TRUE;
   }

 if (s.bcmd != 'H' && s.bcmd != 'Y' && s.bcmd != 'N')
   ulog_user (s.zuser);
 else
   ulog_user ((const char *) NULL);

 switch (s.bcmd)
   {
   case 'S':
   case 'E':
     return fremote_send_file_init (qdaemon, &s, iremote);
   case 'R':
     return fremote_rec_file_init (qdaemon, &s, iremote);
   case 'X':
     return fremote_xcmd_init (qdaemon, &s, iremote);
   case 'H':
     /* This is a remote request for a hangup.  We close the log
        files so that they may be moved at this point.  */
     ulog_close ();
     ustats_close ();
     {
       struct stransfer *q;

       q = qtransalc ((struct scmd *) NULL);
       q->psendfn = fremote_hangup_reply;
       q->iremote = iremote;
       return fqueue_remote (qdaemon, q);
     }
   case 'N':
     /* This means a hangup request is being denied; we just ignore
        this and wait for further commands.  */
     return TRUE;
   case 'Y':
     /* This is a remote confirmation of a hangup.  We reconfirm.  */
     if (qdaemon->fhangup)
       return TRUE;
#if DEBUG > 0
     if (qdaemon->fmaster)
       ulog (LOG_ERROR, "Got hangup reply as master");
#endif
     /* Don't check errors rigorously here, since the other side
        might jump the gun and hang up.  The fLog_sighup variable
        will get set TRUE again when the port is closed.  */
     fLog_sighup = FALSE;
     (void) (*qdaemon->qproto->pfsendcmd) (qdaemon, "HY", 0, iremote);
     qdaemon->fhangup = TRUE;
     return TRUE;
#if DEBUG > 0
   default:
     ulog (LOG_FATAL, "ftadd_cmd: Can't happen");
     return FALSE;
#endif
   }
}
\f
/* The remote system is requesting a hang up.  If we have something to
  do, send an HN.  Otherwise send two HY commands (the other side is
  presumed to send an HY command between the first and second, but we
  don't bother to wait for it) and hang up.  */

static boolean
fremote_hangup_reply (qtrans, qdaemon)
    struct stransfer *qtrans;
    struct sdaemon *qdaemon;
{
 boolean fret;

 utransfree (qtrans);

 if (qTremote == NULL
     && qTlocal == NULL
     && qTsend == NULL
     && qTreceive == NULL)
   {
     if (! fqueue (qdaemon, (boolean *) NULL))
       return FALSE;

     if (qTlocal == NULL)
       {
         DEBUG_MESSAGE0 (DEBUG_UUCP_PROTO, "fremote_hangup_reply: No work");
         fret = ((*qdaemon->qproto->pfsendcmd) (qdaemon, "HY", 0, 0)
                 && (*qdaemon->qproto->pfsendcmd) (qdaemon, "HY", 0, 0));
         qdaemon->fhangup = TRUE;
         return fret;
       }
   }

 DEBUG_MESSAGE0 (DEBUG_UUCP_PROTO, "fremote_hangup_reply: Found work");
 fret = (*qdaemon->qproto->pfsendcmd) (qdaemon, "HN", 0, 0);
 qdaemon->fmaster = TRUE;
 return fret;
}
\f
/* As described in system.h, we need to keep track of which files have
  been successfully received for which we do not know that the other
  system has received our acknowledgement.  This routine is called to
  keep a list of such files.  */

static struct sreceive_ack *qTfree_receive_ack;

void
usent_receive_ack (qdaemon, qtrans)
    struct sdaemon *qdaemon;
    struct stransfer *qtrans;
{
 struct sreceive_ack *q;

 if (qTfree_receive_ack == NULL)
   q = (struct sreceive_ack *) xmalloc (sizeof (struct sreceive_ack));
 else
   {
     q = qTfree_receive_ack;
     qTfree_receive_ack = q->qnext;
   }

 q->qnext = qTreceive_ack;
 q->zto = zbufcpy (qtrans->s.zto);
 q->ztemp = zbufcpy (qtrans->s.ztemp);
 q->fmarked = FALSE;

 qTreceive_ack = q;
}

/* This routine is called by the protocol code when either all
  outstanding data has been acknowledged or one complete window has
  passed.  It may be called directly by the protocol, or it may be
  called via fgot_data.  If one complete window has passed, then all
  unmarked receives are marked, and we know that all marked ones have
  been acked.  */

void
uwindow_acked (qdaemon, fallacked)
    struct sdaemon *qdaemon;
    boolean fallacked;
{
 register struct sreceive_ack **pq;

 pq = &qTreceive_ack;
 while (*pq != NULL)
   {
     if (fallacked || (*pq)->fmarked)
       {
         struct sreceive_ack *q;

         q = *pq;
         (void) fsysdep_forget_reception (qdaemon->qsys, q->zto,
                                          q->ztemp);
         ubuffree (q->zto);
         ubuffree (q->ztemp);
         *pq = q->qnext;
         q->qnext = qTfree_receive_ack;
         qTfree_receive_ack = q;
       }
     else
       {
         (*pq)->fmarked = TRUE;
         pq = &(*pq)->qnext;
       }
   }
}
\f
/* This routine is called when an error occurred and we are crashing
  out of the connection.  It is used to report statistics on failed
  transfers to the statistics file, and it also discards useless
  temporary files for file receptions.  Note that the number of bytes
  we report as having been sent has little or nothing to do with the
  number of bytes the remote site actually received.  */

void
ufailed (qdaemon)
    struct sdaemon *qdaemon;
{
 register struct stransfer *q;

 /* Update the transfer times, but avoid looking in the queue.  */
 iTchecktime = ixsysdep_process_time ((long *) NULL);
 (void) ftcharge (qdaemon, (struct stransfer *) NULL, TRUE, TRUE);
 (void) ftcharge (qdaemon, (struct stransfer *) NULL, FALSE, TRUE);

 if (qTsend != NULL)
   {
     q = qTsend;
     do
       {
         if ((q->fsendfile || q->frecfile)
             && q->cbytes > 0)
           ustats (FALSE, q->s.zuser, qdaemon->qsys->uuconf_zname,
                   q->fsendfile, q->cbytes, q->isecs, q->imicros,
                   FALSE);
         if (q->frecfile)
           (void) frec_discard_temp (qdaemon, q);
         q = q->qnext;
       }
     while (q != qTsend);
   }

 if (qTreceive != NULL)
   {
     q = qTreceive;
     do
       {
         if ((q->fsendfile || q->frecfile)
             && q->cbytes > 0)
           ustats (FALSE, q->s.zuser, qdaemon->qsys->uuconf_zname,
                   q->fsendfile, q->cbytes, q->isecs, q->imicros,
                   FALSE);
         if (q->frecfile)
           (void) frec_discard_temp (qdaemon, q);
         q = q->qnext;
       }
     while (q != qTreceive);
   }
}
\f
/* When a local poll file is found, it is entered on the queue like
  any other job.  When it is pulled off the queue, this function is
  called.  It just calls fsysdep_did_work, which will remove the poll
  file.  This ensures that poll files are only removed if the system
  is actually called.  */

/*ARGSUSED*/
static boolean
flocal_poll_file (qtrans, qdaemon)
    struct stransfer *qtrans;
    struct sdaemon *qdaemon;
{
 boolean fret;

 fret = fsysdep_did_work (qtrans->s.pseq);
 utransfree (qtrans);
 return fret;
}