tcp_unix.c

广泛使用的邮件服务器！同时

    if (!sshcommand) sshcommand = cpystr ("%s %s -l %s exec /etc/r%sd");
  }
				/* want rsh? */
  else if (rshpath && (ti = rshtimeout)) {
				/* rsh command prototype defined yet? */
    if (!rshcommand) rshcommand = cpystr ("%s %s -l %s exec /etc/r%sd");
  }
  else return NIL;		/* rsh disabled */
				/* look like domain literal? */
  if (mb->host[0] == '[' && mb->host[i = (strlen (mb->host))-1] == ']') {
    strcpy (host,mb->host+1);	/* yes, copy without brackets */
    host[i-1] = '\0';
				/* validate domain literal */
    if (adr = ip_stringtoaddr (host,&len,&i)) fs_give ((void **) &adr);
    else {
      sprintf (tmp,"Bad format domain-literal: %.80s",host);
      mm_log (tmp,ERROR);
      return NIL;
    }
  }
  else strcpy (host,tcp_canonical (mb->host));

  if (*service == '*')		/* build ssh command */
    sprintf (tmp,sshcommand,sshpath,host,
	     mb->user[0] ? mb->user : myusername (),service + 1);
  else sprintf (tmp,rshcommand,rshpath,host,
		mb->user[0] ? mb->user : myusername (),service);
  if (tcpdebug) {
    char msg[MAILTMPLEN];
    sprintf (msg,"Trying %.100s",tmp);
    mm_log (msg,TCPDEBUG);
  }
				/* parse command into argv */
  for (i = 1,path = argv[0] = strtok_r (tmp," ",&r);
       (i < MAXARGV) && (argv[i] = strtok_r (NIL," ",&r)); i++);
  argv[i] = NIL;		/* make sure argv tied off */
				/* make command pipes */
  if (pipe (pipei) < 0) return NIL;
  if ((pipei[0] >= FD_SETSIZE) || (pipei[1] >= FD_SETSIZE) ||
      (pipe (pipeo) < 0)) {
    close (pipei[0]); close (pipei[1]);
    return NIL;
  }
  (*bn) (BLOCK_TCPOPEN,NIL);	/* quell alarm up here for NeXT */
  if ((pipeo[0] >= FD_SETSIZE) || (pipeo[1] >= FD_SETSIZE) ||
      ((i = fork ()) < 0)) {	/* make inferior process */
    close (pipei[0]); close (pipei[1]);
    close (pipeo[0]); close (pipeo[1]);
    (*bn) (BLOCK_NONE,NIL);
    return NIL;
  }
  if (!i) {			/* if child */
    alarm (0);			/* never have alarms in children */
    if (!fork ()) {		/* make grandchild so it's inherited by init */
      int cf;			/* don't alter parent vars in case vfork() */
      int maxfd = max (20,max (max(pipei[0],pipei[1]),max(pipeo[0],pipeo[1])));
      dup2 (pipei[1],1);	/* parent's input is my output */
      dup2 (pipei[1],2);	/* parent's input is my error output too */
      dup2 (pipeo[0],0);	/* parent's output is my input */
				/* close all unnecessary descriptors */
      for (cf = 3; cf <= maxfd; cf++) close (cf);
      setpgrp (0,getpid ());	/* be our own process group */
      _exit (execv (path,argv));/* now run it */
    }
    _exit (1);			/* child is done */
  }
  grim_pid_reap (i,NIL);	/* reap child; grandchild now owned by init */
  close (pipei[1]);		/* close child's side of the pipes */
  close (pipeo[0]);

				/* create TCP/IP stream */
  stream = (TCPSTREAM *) memset (fs_get (sizeof (TCPSTREAM)),0,
				 sizeof (TCPSTREAM));
				/* copy remote host name from argument */
  stream->remotehost = cpystr (stream->host = cpystr (host));
  stream->tcpsi = pipei[0];	/* init sockets */
  stream->tcpso = pipeo[1];
  stream->ictr = 0;		/* init input counter */
  stream->port = 0xffffffff;	/* no port number */
  ti += now = time (0);		/* open timeout */
  tmo.tv_usec = 0;		/* initialize usec timeout */
  FD_ZERO (&fds);		/* initialize selection vector */
  FD_ZERO (&efds);		/* handle errors too */
  FD_SET (stream->tcpsi,&fds);	/* set bit in selection vector */
  FD_SET (stream->tcpsi,&efds);	/* set bit in error selection vector */
  FD_SET (stream->tcpso,&efds);	/* set bit in error selection vector */
  do {				/* block under timeout */
    tmo.tv_sec = ti - now;
    i = select (max (stream->tcpsi,stream->tcpso)+1,&fds,NIL,&efds,&tmo);
    now = time (0);		/* fake timeout if interrupt & time expired */
    if ((i < 0) && (errno == EINTR) && ti && (ti <= now)) i = 0;
  } while ((i < 0) && (errno == EINTR));
  if (i <= 0) {			/* timeout or error? */
    sprintf (tmp,i ? "error in %s to IMAP server" :
	     "%s to IMAP server timed out",(*service == '*') ? "ssh" : "rsh");
    mm_log (tmp,WARN);
    tcp_close (stream);		/* punt stream */
    stream = NIL;
  }
  (*bn) (BLOCK_NONE,NIL);
				/* return user name */
  strcpy (usrbuf,mb->user[0] ? mb->user : myusername ());
  return stream;		/* return success */
}

/* TCP receive line
 * Accepts: TCP stream
 * Returns: text line string or NIL if failure
 */

char *tcp_getline (TCPSTREAM *stream)
{
  unsigned long n,contd;
  char *ret = tcp_getline_work (stream,&n,&contd);
  if (ret && contd) {		/* got a line needing continuation? */
    STRINGLIST *stl = mail_newstringlist ();
    STRINGLIST *stc = stl;
    do {			/* collect additional lines */
      stc->text.data = (unsigned char *) ret;
      stc->text.size = n;
      stc = stc->next = mail_newstringlist ();
      ret = tcp_getline_work (stream,&n,&contd);
    } while (ret && contd);
    if (ret) {			/* stash final part of line on list */
      stc->text.data = (unsigned char *) ret;
      stc->text.size = n;
				/* determine how large a buffer we need */
      for (n = 0, stc = stl; stc; stc = stc->next) n += stc->text.size;
      ret = fs_get (n + 1);	/* copy parts into buffer */
      for (n = 0, stc = stl; stc; n += stc->text.size, stc = stc->next)
	memcpy (ret + n,stc->text.data,stc->text.size);
      ret[n] = '\0';
    }
    mail_free_stringlist (&stl);/* either way, done with list */
  }
  return ret;
}

/* TCP receive line or partial line
 * Accepts: TCP stream
 *	    pointer to return size
 *	    pointer to return continuation flag
 * Returns: text line string, size and continuation flag, or NIL if failure
 */

static char *tcp_getline_work (TCPSTREAM *stream,unsigned long *size,
			       long *contd)
{
  unsigned long n;
  char *s,*ret,c,d;
  *contd = NIL;			/* assume no continuation */
				/* make sure have data */
  if (!tcp_getdata (stream)) return NIL;
  for (s = stream->iptr, n = 0, c = '\0'; stream->ictr--; n++, c = d) {
    d = *stream->iptr++;	/* slurp another character */
    if ((c == '\015') && (d == '\012')) {
      ret = (char *) fs_get (n--);
      memcpy (ret,s,*size = n);	/* copy into a free storage string */
      ret[n] = '\0';		/* tie off string with null */
      return ret;
    }
  }
				/* copy partial string from buffer */
  memcpy ((ret = (char *) fs_get (n)),s,*size = n);
				/* get more data from the net */
  if (!tcp_getdata (stream)) fs_give ((void **) &ret);
				/* special case of newline broken by buffer */
  else if ((c == '\015') && (*stream->iptr == '\012')) {
    stream->iptr++;		/* eat the line feed */
    stream->ictr--;
    ret[*size = --n] = '\0';	/* tie off string with null */
  }
  else *contd = LONGT;		/* continuation needed */
  return ret;
}

/* TCP/IP receive buffer
 * Accepts: TCP/IP stream
 *	    size in bytes
 *	    buffer to read into
 * Returns: T if success, NIL otherwise
 */

long tcp_getbuffer (TCPSTREAM *stream,unsigned long size,char *s)
{
  unsigned long n;
				/* make sure socket still alive */
  if (stream->tcpsi < 0) return NIL;
				/* can transfer bytes from buffer? */
  if (n = min (size,stream->ictr)) {
    memcpy (s,stream->iptr,n);	/* yes, slurp as much as we can from it */
    s += n;			/* update pointer */
    stream->iptr +=n;
    size -= n;			/* update # of bytes to do */
    stream->ictr -=n;
  }
  if (size) {
    int i;
    fd_set fds,efds;
    struct timeval tmo;
    time_t t = time (0);
    blocknotify_t bn=(blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
    (*bn) (BLOCK_TCPREAD,NIL);
    while (size > 0) {		/* until request satisfied */
      time_t tl = time (0);
      time_t now = tl;
      time_t ti = ttmo_read ? now + ttmo_read : 0;
      if (tcpdebug) mm_log ("Reading TCP buffer",TCPDEBUG);
      tmo.tv_usec = 0;
      FD_ZERO (&fds);		/* initialize selection vector */
      FD_ZERO (&efds);		/* handle errors too */
				/* set bit in selection vectors */
      FD_SET (stream->tcpsi,&fds);
      FD_SET (stream->tcpsi,&efds);
      errno = NIL;		/* initially no error */
      do {			/* block under timeout */
	tmo.tv_sec = ti ? ti - now : 0;
	i = select (stream->tcpsi+1,&fds,NIL,&efds,ti ? &tmo : NIL);
	now = time (0);		/* fake timeout if interrupt & time expired */
	if ((i < 0) && (errno == EINTR) && ti && (ti <= now)) i = 0;
      } while ((i < 0) && (errno == EINTR));
      if (i) {			/* non-timeout result from select? */
	if (i > 0)		/* read what we can */
	  while (((i = read (stream->tcpsi,s,(int) min (maxposint,size))) < 0)
		 && (errno == EINTR));
	if (i <= 0) {		/* error seen? */
	  if (tcpdebug) {
	    char tmp[MAILTMPLEN];
	    if (i) sprintf (s = tmp,"TCP buffer read I/O error %d",errno);
	    else s = "TCP buffer read end of file";
	    mm_log (s,TCPDEBUG);
	  }
	  return tcp_abort (stream);
	}
	s += i;			/* success, point at new place to write */
	size -= i;		/* reduce byte count */
	if (tcpdebug) mm_log ("Successfully read TCP buffer",TCPDEBUG);
      }
				/* timeout, punt unless told not to */
      else if (!tmoh || !(*tmoh) (now - t,now - tl)) {
	if (tcpdebug) mm_log ("TCP buffer read timeout",TCPDEBUG);
	return tcp_abort (stream);
      }
    }
    (*bn) (BLOCK_NONE,NIL);
  }
  *s = '\0';			/* tie off string */
  return LONGT;
}

/* TCP/IP receive data
 * Accepts: TCP/IP stream
 * Returns: T if success, NIL otherwise
 */

long tcp_getdata (TCPSTREAM *stream)
{
  int i;
  fd_set fds,efds;
  struct timeval tmo;
  time_t t = time (0);
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
  if (stream->tcpsi < 0) return NIL;
  (*bn) (BLOCK_TCPREAD,NIL);
  while (stream->ictr < 1) {	/* if nothing in the buffer */
    time_t tl = time (0);	/* start of request */
    time_t now = tl;
    time_t ti = ttmo_read ? now + ttmo_read : 0;
    if (tcpdebug) mm_log ("Reading TCP data",TCPDEBUG);
    tmo.tv_usec = 0;
    FD_ZERO (&fds);		/* initialize selection vector */
    FD_ZERO (&efds);		/* handle errors too */
    FD_SET (stream->tcpsi,&fds);/* set bit in selection vectors */
    FD_SET (stream->tcpsi,&efds);
    errno = NIL;		/* initially no error */
    do {			/* block under timeout */
      tmo.tv_sec = ti ? ti - now : 0;
      i = select (stream->tcpsi+1,&fds,NIL,&efds,ti ? &tmo : NIL);
      now = time (0);		/* fake timeout if interrupt & time expired */
      if ((i < 0) && (errno == EINTR) && ti && (ti <= now)) i = 0;
    } while ((i < 0) && (errno == EINTR));
    if (i) {			/* non-timeout result from select? */
				/* read what we can */
      if (i > 0) while (((i = read (stream->tcpsi,stream->ibuf,BUFLEN)) < 0) &&
			(errno == EINTR));
      if (i <= 0) {		/* error seen? */
	if (tcpdebug) {
	  char *s,tmp[MAILTMPLEN];
	  if (i) sprintf (s = tmp,"TCP data read I/O error %d",errno);
	  else s = "TCP data read end of file";
	  mm_log (s,TCPDEBUG);
	}
	return tcp_abort (stream);
      }
      stream->ictr = i;		/* success, set new count and pointer */
      stream->iptr = stream->ibuf;
      if (tcpdebug) mm_log ("Successfully read TCP data",TCPDEBUG);
    }
				/* timeout, punt unless told not to */
    else if (!tmoh || !(*tmoh) (now - t,now - tl)) {
      if (tcpdebug) mm_log ("TCP data read timeout",TCPDEBUG);
      return tcp_abort (stream);/* error or timeout no-continue */
    }
  }
  (*bn) (BLOCK_NONE,NIL);
  return T;
}

/* TCP/IP send string as record
 * Accepts: TCP/IP stream
 *	    string pointer
 * Returns: T if success else NIL
 */

long tcp_soutr (TCPSTREAM *stream,char *string)
{
  return tcp_sout (stream,string,(unsigned long) strlen (string));
}


/* TCP/IP send string
 * Accepts: TCP/IP stream
 *	    string pointer
 *	    byte count
 * Returns: T if success else NIL
 */

long tcp_sout (TCPSTREAM *stream,char *string,unsigned long size)
{
  int i;
  fd_set fds,efds;
  struct timeval tmo;
  time_t t = time (0);
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
  if (stream->tcpso < 0) return NIL;
  (*bn) (BLOCK_TCPWRITE,NIL);
  while (size > 0) {		/* until request satisfied */
    time_t tl = time (0);	/* start of request */
    time_t now = tl;
    time_t ti = ttmo_write ? now + ttmo_write : 0;
    if (tcpdebug) mm_log ("Writing to TCP",TCPDEBUG);
    tmo.tv_usec = 0;
    FD_ZERO (&fds);		/* initialize selection vector */
    FD_ZERO (&efds);		/* handle errors too */
    FD_SET (stream->tcpso,&fds);/* set bit in selection vector */
    FD_SET(stream->tcpso,&efds);/* set bit in error selection vector */
    errno = NIL;		/* block and write */
    do {			/* block under timeout */