/* ========================================================================
 * Copyright 2008-2010 Mark Crispin
 * ========================================================================
 */

/*
 * Program:	MS-DOS TCP/IP routines
 *
 * Author:	Mark Crispin
 *
 * Date:	11 April 1989
 * Last Edited:	3 April 2010
 *
 * Previous versions of this file were:
 *
 * Copyright 1988-2008 University of Washington
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 */

static tcptimeout_t tmoh = NIL;	/* TCP timeout handler routine */
static long ttmo_read = 0;	/* TCP timeouts, in seconds */
static long ttmo_write = 0;

static char *tcp_getline_work (TCPSTREAM *stream,unsigned long *size,
			       long *contd);

/* TCP/IP manipulate parameters
 * Accepts: function code
 *	    function-dependent value
 * Returns: function-dependent return value
 */

void *tcp_parameters (long function,void *value)
{
  void *ret = NIL;
  switch ((int) function) {
  case SET_TIMEOUT:
    tmoh = (tcptimeout_t) value;
  case GET_TIMEOUT:
    ret = (void *) tmoh;
    break;
  case SET_READTIMEOUT:
    ttmo_read = (long) value;
  case GET_READTIMEOUT:
    ret = (void *) ttmo_read;
    break;
  case SET_WRITETIMEOUT:
    ttmo_write = (long) value;
  case GET_WRITETIMEOUT:
    ret = (void *) ttmo_write;
    break;
  }
  return ret;
}

/* TCP/IP open
 * Accepts: host name
 *	    contact service name
 *	    contact port number
 * Returns: TCP/IP stream if success else NIL
 */

TCPSTREAM *tcp_open (char *host,char *service,unsigned long port)
{
  TCPSTREAM *stream = NIL;
  struct sockaddr_in sin;
  int sock;
  char *s,tmp[MAILTMPLEN];
  port &= 0xffff;		/* erase flags */
  /* The domain literal form is used (rather than simply the dotted decimal
     as with other Unix programs) because it has to be a valid "host name"
     in mailsystem terminology. */
  sin.sin_family = AF_INET;	/* family is always Internet */
				/* look like domain literal? */
  if (host[0] == '[' && host[(strlen (host))-1] == ']') {
    strcpy (tmp,host+1);	/* yes, copy number part */
    tmp[strlen (tmp)-1] = '\0';
    if ((sin.sin_addr.s_addr = inet_addr (tmp)) == -1) {
      sprintf (tmp,"Bad format domain-literal: %.80s",host);
      mm_log (tmp,ERROR);
      return NIL;
    }
  }
				/* look up host name */
  else if (!lookuphost (&host,&sin)) {
    sprintf (tmp,"Host not found: %s",host);
    mm_log (tmp,ERROR);
    return NIL;
  }

				/* copy port number in network format */
  if (!(sin.sin_port = htons (port))) fatal ("Bad port argument to tcp_open");
				/* get a TCP stream */
  if ((sock = socket (sin.sin_family,SOCK_STREAM,0)) < 0) {
    sprintf (tmp,"Unable to create TCP socket (%d)",errno);
    mm_log (tmp,ERROR);
    fs_give ((void **) &host);
    return NIL;
  }
#if 0
  /* needed? */
  else if (sock >= FD_SETSIZE) {/* unselectable sockets are useless */
    sprintf (tmp,"Unable to create selectable TCP socket (%d >= %d)",
	     sock,FD_SETSIZE);
    close (sock);
    errno = ENOBUFS;		/* just in case */
    return NIL;
  }
#endif
				/* open connection */
  if (connect (sock,(struct sockaddr *) &sin,sizeof (sin)) < 0) {
    switch (errno) {		/* analyze error */
    case ECONNREFUSED:
      s = "Refused";
      break;
    case ENOBUFS:
      s = "Insufficient system resources";
      break;
    case ETIMEDOUT:
      s = "Timed out";
      break;
    default:
      s = "Unknown error";
      break;
    }
    sprintf (tmp,"Can't connect to %.80s,%ld: %s (%d)",host,port,s,errno);
    mm_log (tmp,ERROR);
    close (sock);
    fs_give ((void **) &host);
    return NIL;
  }
				/* create TCP/IP stream */
  stream = (TCPSTREAM *) fs_get (sizeof (TCPSTREAM));
  stream->host = host;		/* official host name */
  stream->localhost = cpystr (mylocalhost ());
  stream->port = port;		/* port number */
  stream->tcps = sock;		/* init socket */
  stream->ictr = 0;		/* init input counter */
  return stream;		/* return success */
}
  
/* TCP/IP authenticated open
 * Accepts: NETMBX specifier
 *	    service name
 *	    returned user name buffer
 * Returns: TCP/IP stream if success else NIL
 */

TCPSTREAM *tcp_aopen (NETMBX *mb,char *service,char *usrbuf)
{
  return NIL;			/* always NIL on DOS */
}

/* 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 *buffer)
{
  unsigned long n;
  char *bufptr = buffer;
  while (size > 0) {		/* until request satisfied */
    if (!tcp_getdata (stream)) return NIL;
    n = min (size,stream->ictr);/* number of bytes to transfer */
				/* do the copy */
    memcpy (bufptr,stream->iptr,n);
    bufptr += n;		/* update pointer */
    stream->iptr +=n;
    size -= n;			/* update # of bytes to do */
    stream->ictr -=n;
  }
  bufptr[0] = '\0';		/* tie off string */
  return T;
}

/* 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);
  if (stream->tcps < 0) return NIL;
  while (stream->ictr < 1) {	/* if nothing in the buffer */
    time_t tl = time (0);	/* start of request */
    tmo.tv_sec = ttmo_read;	/* read timeout */
    tmo.tv_usec = 0;
    FD_ZERO (&fds);		/* initialize selection vector */
    FD_ZERO (&efds);		/* handle errors too */
    FD_SET (stream->tcps,&fds);/* set bit in selection vector */
    FD_SET(stream->tcps,&efds);/* set bit in error selection vector */
    errno = NIL;		/* block and read */
    while (((i = select (stream->tcps+1,&fds,0,&efds,ttmo_read ? &tmo : 0))<0)
	   && (errno == EINTR));
    if (!i) {			/* timeout? */
      time_t tc = time (0);
      if (tmoh && ((*tmoh) (tc - t,tc - tl))) continue;
      else return tcp_abort (stream);
    }
    else if (i < 0) return tcp_abort (stream);
    while (((i = read (stream->tcps,stream->ibuf,BUFLEN)) < 0) &&
	   (errno == EINTR));
    if (i < 1) return tcp_abort (stream);
    stream->iptr = stream->ibuf;/* point at TCP buffer */
    stream->ictr = i;		/* set new byte count */
  }
  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;
  struct timeval tmo;
  time_t t = time (0);
  if (stream->tcps < 0) return NIL;
  while (size > 0) {		/* until request satisfied */
    time_t tl = time (0);	/* start of request */
    tmo.tv_sec = ttmo_write;	/* write timeout */
    tmo.tv_usec = 0;
    FD_ZERO (&fds);		/* initialize selection vector */
    FD_SET (stream->tcps,&fds);/* set bit in selection vector */
    errno = NIL;		/* block and write */
    while (((i = select (stream->tcps+1,0,&fds,0,ttmo_write ? &tmo : 0)) < 0)
	   && (errno == EINTR));
    if (!i) {			/* timeout? */
      time_t tc = time (0);
      if (tmoh && ((*tmoh) (tc - t,tc - tl))) continue;
      else return tcp_abort (stream);
    }
    else if (i < 0) return tcp_abort (stream);
    while (((i = write (stream->tcps,string,size)) < 0) && (errno == EINTR));
    if (i < 0) return tcp_abort (stream);
    size -= i;			/* how much we sent */
    string += i;
  }
  return T;			/* all done */
}

/* TCP/IP close
 * Accepts: TCP/IP stream
 */

void tcp_close (TCPSTREAM *stream)
{
  tcp_abort (stream);		/* nuke the socket */
				/* flush host names */
  fs_give ((void **) &stream->host);
  fs_give ((void **) &stream->localhost);
  fs_give ((void **) &stream);	/* flush the stream */
}


/* TCP/IP abort stream
 * Accepts: TCP/IP stream
 * Returns: NIL always
 */

long tcp_abort (TCPSTREAM *stream)
{
  if (stream->tcps >= 0) close (stream->tcps);
  stream->tcps = -1;
  return NIL;
}

/* TCP/IP get host name
 * Accepts: TCP/IP stream
 * Returns: host name for this stream
 */

char *tcp_host (TCPSTREAM *stream)
{
  return stream->host;		/* return host name */
}


/* TCP/IP get remote host name
 * Accepts: TCP/IP stream
 * Returns: host name for this stream
 */

char *tcp_remotehost (TCPSTREAM *stream)
{
  return stream->host;		/* all we can do for now */
}


/* TCP/IP return port for this stream
 * Accepts: TCP/IP stream
 * Returns: port number for this stream
 */

unsigned long tcp_port (TCPSTREAM *stream)
{
  return stream->port;		/* return port number */
}


/* TCP/IP get local host name
 * Accepts: TCP/IP stream
 * Returns: local host name
 */

char *tcp_localhost (TCPSTREAM *stream)
{
  return stream->localhost;	/* return local host name */
}


/* TCP/IP return canonical form of host name
 * Accepts: host name
 * Returns: canonical form of host name
 */

char *tcp_canonical (char *name)
{
  return cpystr (name);
}


/* TCP/IP get client host name (server calls only)
 * Returns: client host name
 */

char *tcp_clienthost ()
{
  return "UNKNOWN";
}