imapd.c

广泛使用的邮件服务器！同时

	PSOUT (")\015\012");
      }
    }
    else {			/* driver changed */
      new_flags (stream);	/* send mailbox flags */
      if (curdriver) {		/* note readonly/write if possible change */
	PSOUT ("* OK [READ-");
	PSOUT (stream->rdonly ? "ONLY" : "WRITE");
	PSOUT ("] Mailbox status\015\012");
      }
      curdriver = stream->dtb;
      if (nmsgs) {		/* get flags for all messages */
	sprintf (tmp,"1:%lu",nmsgs);
	mail_fetch_flags (stream,tmp,NIL);
				/* don't do this if newsrc already did */
	if (!(curdriver->flags & DR_NEWS)) {
				/* find first unseen message */
	  for (i = 1; i <= nmsgs && mail_elt (stream,i)->seen; i++);
	  if (i <= nmsgs) {
	    PSOUT ("* OK [UNSEEN ");
	    pnum (i);
	    PSOUT ("] first unseen message in ");
	    PSOUT (stream->mailbox);
	    CRLF;
	  }
	}
      }
    }
  }
  if (shutdowntime && (time (0) > shutdowntime + SHUTDOWNTIMER)) {
    PSOUT ("* BYE Server shutting down\015\012");
    state = LOGOUT;
  }
				/* don't do these stat()s every cycle */
  else if (time (0) > alerttime + ALERTTIMER) { 
    struct stat sbuf;
				/* have a shutdown file? */
    if (!stat (SHUTDOWNFILE,&sbuf)) {
      PSOUT ("* OK [ALERT] Server shutting down shortly\015\012");
      shutdowntime = time (0);
    }
    alerttime = time (0);	/* output any new alerts */
    sysalerttime = palert (ALERTFILE,sysalerttime);
    if (state != LOGIN)		/* do user alert if logged in */
      useralerttime = palert (mailboxfile (tmp,USERALERTFILE),useralerttime);
  }
}

/* Print an alert file
 * Accepts: path of alert file
 *	    time of last printed alert file
 * Returns: updated time of last printed alert file
 */

time_t palert (char *file,time_t oldtime)
{
  FILE *alf;
  struct stat sbuf;
  int c,lc = '\012';
				/* have a new alert file? */
  if (stat (file,&sbuf) || (sbuf.st_mtime <= oldtime) ||
      !(alf = fopen (file,"r"))) return oldtime;
				/* yes, display it */
  while ((c = getc (alf)) != EOF) {
    if (lc == '\012') PSOUT ("* OK [ALERT] ");
    switch (c) {		/* output character */
    case '\012':		/* newline means do CRLF */
      CRLF;
    case '\015':		/* flush CRs */
    case '\0':			/* flush nulls */
      break;
    default:
      PBOUT (c);		/* output all other characters */
      break;
    }
    lc = c;			/* note previous character */
  }
  fclose (alf);
  if (lc != '\012') CRLF;	/* final terminating CRLF */
  return sbuf.st_mtime;		/* return updated last alert time */
}

/* Initialize file string structure for file stringstruct
 * Accepts: string structure
 *	    pointer to message data structure
 *	    size of string
 */

void msg_string_init (STRING *s,void *data,unsigned long size)
{
  MSGDATA *md = (MSGDATA *) data;
  s->data = data;		/* note stream/msgno and header length */
#if 0
  s->size = size;		/* message size */
  s->curpos = s->chunk =	/* load header */
    mail_fetchheader_full (md->stream,md->msgno,NIL,&s->data1,
			   FT_PREFETCHTEXT | FT_PEEK);
#else	/* This kludge is necessary because of broken mail stores */
  mail_fetchtext_full (md->stream,md->msgno,&s->size,FT_PEEK);
  s->curpos = s->chunk =	/* load header */
    mail_fetchheader_full (md->stream,md->msgno,NIL,&s->data1,FT_PEEK);
  s->size += s->data1;		/* header + body size */
#endif
  s->cursize = s->chunksize = s->data1;
  s->offset = 0;		/* offset is start of message */
}


/* Get next character from file stringstruct
 * Accepts: string structure
 * Returns: character, string structure chunk refreshed
 */

char msg_string_next (STRING *s)
{
  char c = *s->curpos++;	/* get next byte */
  SETPOS (s,GETPOS (s));	/* move to next chunk */
  return c;			/* return the byte */
}


/* Set string pointer position for file stringstruct
 * Accepts: string structure
 *	    new position
 */

void msg_string_setpos (STRING *s,unsigned long i)
{
  MSGDATA *md = (MSGDATA *) s->data;
  if (i < s->data1) {		/* want header? */
    s->chunk = mail_fetchheader_full (md->stream,md->msgno,NIL,NIL,FT_PEEK);
    s->chunksize = s->data1;	/* header length */
    s->offset = 0;		/* offset is start of message */
  }
  else if (i < s->size) {	/* want body */
    s->chunk = mail_fetchtext_full (md->stream,md->msgno,NIL,FT_PEEK);
    s->chunksize = s->size - s->data1;
    s->offset = s->data1;	/* offset is end of header */
  }
  else {			/* off end of message */
    s->chunk = NIL;		/* make sure that we crack on this then */
    s->chunksize = 1;		/* make sure SNX cracks the right way... */
    s->offset = i;
  }
				/* initial position and size */
  s->curpos = s->chunk + (i -= s->offset);
  s->cursize = s->chunksize - i;
}

/* Send flags for stream
 * Accepts: MAIL stream
 *	    scratch buffer
 */

void new_flags (MAILSTREAM *stream)
{
  int i,c;
  PSOUT ("* FLAGS (");
  for (i = 0; i < NUSERFLAGS; i++) if (stream->user_flags[i]) {
    PSOUT (stream->user_flags[i]);
    PBOUT (' ');
    nflags = i + 1;
  }
  PSOUT ("\\Answered \\Flagged \\Deleted \\Draft \\Seen)\015\012* OK [PERMANENTFLAGS (");
  for (i = c = 0; i < NUSERFLAGS; i++)
    if ((stream->perm_user_flags & (1 << i)) && stream->user_flags[i])
      put_flag (&c,stream->user_flags[i]);
  if (stream->kwd_create) put_flag (&c,"\\*");
  if (stream->perm_answered) put_flag (&c,"\\Answered");
  if (stream->perm_flagged) put_flag (&c,"\\Flagged");
  if (stream->perm_deleted) put_flag (&c,"\\Deleted");
  if (stream->perm_draft) put_flag (&c,"\\Draft");
  if (stream->perm_seen) put_flag (&c,"\\Seen");
  PSOUT (")] Permanent flags\015\012");
}

/* Set timeout
 * Accepts: desired interval
 */

void settimeout (unsigned int i)
{
				/* limit if not logged in */
  if (i) alarm ((state == LOGIN) ? LOGINTIMEOUT : i);
  else alarm (0);
}


/* Clock interrupt
 * Returns only if critical code in progress
 */

void clkint (void)
{
  settimeout (0);		/* disable all interrupts */
  server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
  logout = "Autologout";
  goodbye = "Autologout (idle for too long)";
  if (critical) {		/* must defer if in critical code(?) */
    close (0);			/* kill stdin */
    state = LOGOUT;		/* die as soon as we can */
  }
  else longjmp (jmpenv,1);	/* die now */
}


/* Kiss Of Death interrupt
 * Returns only if critical code in progress
 */

void kodint (void)
{
  settimeout (0);		/* disable all interrupts */
  server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
  logout = goodbye = "Killed (lost mailbox lock)";
  if (critical) {		/* must defer if in critical code */
    close (0);			/* kill stdin */
    state = LOGOUT;		/* die as soon as we can */
  }
  else longjmp (jmpenv,1);	/* die now */
}

/* Hangup interrupt
 * Returns only if critical code in progress
 */

void hupint (void)
{
  settimeout (0);		/* disable all interrupts */
  server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
  logout = "Hangup";
  goodbye = NIL;		/* other end is already gone */
  if (critical) {		/* must defer if in critical code */
    close (0);			/* kill stdin */
    close (1);			/* and stdout */
    state = LOGOUT;		/* die as soon as we can */
  }
  else longjmp (jmpenv,1);	/* die now */
}


/* Termination interrupt
 * Returns only if critical code in progress
 */

void trmint (void)
{
  settimeout (0);		/* disable all interrupts */
  server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
  logout = goodbye = "Killed (terminated)";
  /* Make no attempt at graceful closure since a shutdown may be in
   * progress, and we won't have any time to do mail_close() actions
   */
  stream = NIL;
  if (critical) {		/* must defer if in critical code */
    close (0);			/* kill stdin */
    close (1);			/* and stdout */
    state = LOGOUT;		/* die as soon as we can */
  }
  else longjmp (jmpenv,1);	/* die now */
}

/* The routines on this and the next page eschew the use of non-syscall libc
 * routines (especially stdio) for a reason.  Also, these hideous #if
 * condtionals need to be replaced.
 */

#ifndef unix
#define unix 0
#endif


/* Status request interrupt
 * Always returns
 */

void staint (void)
{
#if unix
  int fd;
  char *s,buf[8*MAILTMPLEN];
  unsigned long pid = getpid ();
				/* build file name */
  s = nout (sout (buf,"/tmp/imapd-status."),pid,10);
  if (user) s = sout (sout (s,"."),user);
  *s = '\0';			/* tie off file name */
  if ((fd = open (buf,O_WRONLY | O_CREAT | O_TRUNC,0666)) >= 0) {
    fchmod (fd,0666);
    s = nout (sout (buf,"PID="),pid,10);
    if (user) s = sout (sout (s,", user="),user);
    switch (state) {
    case LOGIN:
      s = sout (s,", not logged in");
      break;
    case SELECT:
      s = sout (s,", logged in");
      break;
    case OPEN:
      s = sout (s,", mailbox open");
      break;
    case LOGOUT:
      s = sout (s,", logging out");
      break;
    }
    if (stream && stream->mailbox)
      s = sout (sout (s,"\nmailbox="),stream->mailbox);
    *s++ = '\n';
    if (status) {
      s = sout (s,status);
      if (cmd) s = sout (sout (s,", last command="),cmd);
    }
    else s = sout (sout (s,cmd)," in progress");
    *s++ = '\n';
    write (fd,buf,s-buf);
    close (fd);
  }
#endif
}

/* Write string
 * Accepts: destination string pointer
 *	    string
 * Returns: updated string pointer
 */

char *sout (char *s,char *t)
{
  while (*t) *s++ = *t++;
  return s;
}


/* Write number
 * Accepts: destination string pointer
 *	    number
 *	    base
 * Returns: updated string pointer
 */

char *nout (char *s,unsigned long n,unsigned long base)
{
  char stack[256];
  char *t = stack;
				/* push PID digits on stack */
  do *t++ = (char) (n % base) + '0';
  while (n /= base);
				/* pop digits from stack */
  while (t > stack) *s++ = *--t;
  return s;
}

/* Slurp a command line
 * Accepts: buffer pointer
 *	    buffer size
 *	    input timeout
 */

void slurp (char *s,int n,unsigned long timeout)
{
  memset (s,'\0',n);		/* zap buffer */
  if (state != LOGOUT) {	/* get a command under timeout */
    settimeout (timeout);
    clearerr (stdin);		/* clear stdin errors */
    status = "reading line";
    if (!PSIN (s,n-1)) ioerror (stdin,status);
    settimeout (0);		/* make sure timeout disabled */
    status = NIL;
  }
}


/* Read a literal
 * Accepts: destination buffer (must be size+1 for trailing NUL)
 *	    size of buffer (must be less than 4294967295)
 */

void inliteral (char *s,unsigned long n)
{
  unsigned long i;
  if (litplus.ok) {		/* no more LITERAL+ to worry about */
    litplus.ok = NIL;
    litplus.size = 0;
  }
  else {			/* otherwise tell client ready for argument */
    PSOUT ("+ Ready for argument\015\012");
    PFLUSH ();			/* dump output buffer */
  }
  clearerr (stdin);		/* clear stdin errors */
  memset (s,'\0',n+1);		/* zap buffer */
  status