tcpip.c

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// Maurice LeBrun
// 6-Jan-94
//
// Functions to handle a variety of TPC-IP related chores, in particular
// socket i/o for data transfer to the Tcl-DP driver.  For the latter, the
// Tcl-DP routines were modified to use binary records; copyright follows:
//
// Copyright 1992 Telecom Finland
//
// Permission to use, copy, modify, and distribute this
// software and its documentation for any purpose and without
// fee is hereby granted, provided that this copyright
// notice appears in all copies.  Telecom Finland
// makes no representations about the suitability of this
// software for any purpose.  It is provided "as is" without
// express or implied warranty.
//
// Copyright (c) 1993 The Regents of the University of California.
// All rights reserved.
//
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without written agreement is
// hereby granted, provided that the above copyright notice and the following
// two paragraphs appear in all copies of this software.
//
// IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
// DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
// OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
// CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
// PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
//
//
// Copyright (C) 2004  Joao Cardoso
//
// This file is part of PLplot.
//
// PLplot is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published
// by the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// PLplot 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 Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with PLplot; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//

//
// #define DEBUG
//

#include "plDevs.h"
#include "plConfig.h"

#if defined ( PLD_tk ) || defined ( ENABLE_tkX )

// This file is meant to be compiled with non-ANSI compilers ("cc").
// The reason for doing it this way is to ensure that the full C
// environment of the target machine is visible (at the time of writing
// this, parts of this code are not covered by any international
// standard).  ANSI compilers are required to omit these extra symbols,
// and at the moment there is no way to get them back except for by
// vendor-specific defines, e.g. _HPUX_SOURCE (HP), _ALL_SOURCE (AIX),
// _DGUX_SOURCE (DGUX).  This is an omission in the POSIX standard more
// than anything else, and will probably be rectified at some point.  So
// for now, instead of relying on a hodgepodge of vendor specific symbols
// I forego the ANSI compiler here and go with good (bad) old "cc".
//

#ifdef _POSIX_SOURCE
#undef _POSIX_SOURCE
#endif
#ifdef caddr_t
#undef caddr_t
#endif

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#if defined ( __sgi ) && !defined ( SVR3 )
#include <sys/select.h>
#endif
#ifdef PL_HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "plplot.h"
#include "tcpip.h"
#include <tcl.h>
#include <tk.h>

#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <ctype.h>
#if !defined ( _WIN32 )
#include <sys/uio.h>
#endif
#include <errno.h>

#if defined ( _WIN32 )
// This is the source of the WSAEWOULDBLOCK macro on Windows platforms.
  #include <winerror.h>
#endif

#if defined ( EWOULDBLOCK )
  #define PLPLOT_EWOULDBLOCK    EWOULDBLOCK
#elif defined ( WSAEWOULDBLOCK )
  #define PLPLOT_EWOULDBLOCK    WSAEWOULDBLOCK
#else
  #error broken system where neither EWOULDBLOCK nor WSAEWOULDBLOCK macros are #defined
#endif

// Supply dummy macros for the low-level I/O functions - Windows
#if defined ( _WIN32 )
#define read( a, b, c )     0
#define close( a )
#define write( a, b, c )    0
#endif

//extern int errno;

#ifndef MIN
#define MIN( a, b )    ( ( ( a ) < ( b ) ) ? ( a ) : ( b ) )
#endif

//
// This is a "magic number" prepended to the beginning of the packet
// Used to help resync the packet machanism in the event of errors.
//
#define PACKET_MAGIC    0x6feeddcc

//
// For TCP, it's possible to get a line in pieces.  In case everything we
// want isn't there, we need a place to store partial results when we're
// in non-blocking mode.  The partial buffers below are created
// dynamically to store incomplete data in these cases.
//

typedef struct PartialRead
{
    char *buffer;               // Buffer of characters
    int  bufSize;               // Size of buffer
    int  offset;                // Offset of current character within buffer
    struct PartialRead *next;   // Next buffer in chain
} PartialRead;

#define MAX_OPEN_FILES    128

static PartialRead *partial[MAX_OPEN_FILES];

static void pl_FreeReadBuffer( int fd );
static void pl_Unread( int fd, char *buffer, int numBytes, int copy );
static int  pl_Read( int fd, char *buffer, int numReq );

int pl_PacketReceive( Tcl_Interp * interp, PLiodev *iodev, PDFstrm *pdfs );
int pl_PacketSend( Tcl_Interp * interp, PLiodev *iodev, PDFstrm *pdfs );

//
//--------------------------------------------------------------------------
//
// pl_FreeReadBuffer --
//
//      This function is called to free up all the memory associated
//      with a file once the file is closed.
//
// Results:
//      None.
//
// Side effects:
//      Any data buffered locally will be lost.
//
//--------------------------------------------------------------------------
//

static void
pl_FreeReadBuffer( int fd )
{
    PartialRead *readList;

    while ( partial[fd] != NULL )
    {
        readList    = partial[fd];
        partial[fd] = readList->next;
        free( readList->buffer );
        free( readList );
    }
}

//
//--------------------------------------------------------------------------
//
// pl_Unread --
//
//      This function puts data back into the read chain on a
//      file descriptor.  It's basically an extended "ungetc".
//
// Results:
//      None.
//
// Side effects:
//      Subsequent calls to pl_Read on the fd will get this data.
//
//--------------------------------------------------------------------------
//

static void
pl_Unread( int fd, char *buffer, int numBytes, int copy )
//int fd;                         // File descriptor
//char *buffer;                   // Data to unget
//int  numBytes;                  // Number of bytes to unget
//int  copy;                      // Should we copy the data, or use this
// buffer?
{
    PartialRead *new;

    new = (PartialRead *) malloc( sizeof ( PartialRead ) );
    if ( copy )
    {
        new->buffer = (char *) malloc( (size_t) numBytes );
        memcpy( new->buffer, buffer, (size_t) numBytes );
    }
    else
    {
        new->buffer = buffer;
    }
    new->bufSize = numBytes;
    new->offset  = 0;
    new->next    = partial[fd];
    partial[fd]  = new;
}

//
//--------------------------------------------------------------------------
//
// pl_Read --
//
//      This function implements a "read"-like command, but
//      buffers partial reads.  The semantics are the same as
//      with read.
//
// Results:
//      Number of bytes read, or -1 on error (with errno set).
//
// Side effects:
//      All available data is read from the file descriptor.
//
//--------------------------------------------------------------------------
//

static int
pl_Read( int fd, char *buffer, int numReq )
//int fd;                         // File descriptor to read from
//char *buffer;                   // Place to put the data
//int  numReq;                    // Number of bytes to get
{
    PartialRead *readList;
    PartialRead *tmp;
    int         numRead;
    int         numToCopy;

    readList = partial[fd];

    //
    // If there's no data left over from a previous read, then just do a read
    // This is the common case.
    //
    if ( readList == NULL )
    {
        numRead = (int) read( fd, buffer, (size_t) numReq );
#ifdef DEBUG
        {
            int j;
            fprintf( stderr, "received %d bytes starting with:", numRead );
            for ( j = 0; j < MIN( 8, numRead ); j++ )
                fprintf( stderr, " %x", 0x000000FF & (unsigned long) buffer[j] );
            fprintf( stderr, "\n" );
        }
#endif
        return numRead;
    }

    //
    // There's data left over from a previous read.  Yank it in and
    // only call read() if we didn't get enough data (this keeps the fd
    // readable if they only request as much data as is in the buffers).
    //
    numRead = 0;
    while ( ( readList != NULL ) && ( numRead < numReq ) )
    {
        numToCopy = readList->bufSize - readList->offset;
        if ( numToCopy + numRead > numReq )
        {
            numToCopy = numReq - numRead;
        }
        memcpy( buffer + numRead, readList->buffer + readList->offset, (size_t) numToCopy );

        //
        // Consume the data
        //
        tmp          = readList;
        readList     = readList->next;
        tmp->offset += numToCopy;
        if ( tmp->offset == tmp->bufSize )
        {
            free( tmp->buffer );
            free( tmp );
            partial[fd] = readList;
        }
        numRead += numToCopy;
    }

    //
    // Only call read if at the end of a previously incomplete packet.
    //
    if ( ( numRead < numReq ) )
    {
        numToCopy = numReq - numRead;
        numRead  += (int) read( fd, buffer + numRead, (size_t) numToCopy );
    }

    return numRead;
}

//--------------------------------------------------------------------------
//  This part for Tcl-DP only
//--------------------------------------------------------------------------

#ifdef PLD_dp

#include <dp.h>

#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>

//--------------------------------------------------------------------------
// plHost_ID
//
// Tcl command -- return the IP address for the current host.
//
// Derived from source code in "UNIX Network Programming" by W. Richard
// Stevens, Prentice Hall, 1990.
//--------------------------------------------------------------------------

static char *
get_inet( char ** listptr, int length )
{
    struct in_addr *ptr;

    while ( ( ptr = (struct in_addr *) *listptr++ ) == NULL )
        continue;

    return inet_ntoa( *ptr );
}

int
plHost_ID( ClientData clientData, Tcl_Interp *interp, int argc, char **argv )
{
    register struct hostent *hostptr;
    char hostname[100];

    if ( gethostname( hostname, 100 ) )
    {
        Tcl_AppendResult( interp, "Error -- cannot get host name",
            (char *) NULL );
        return TCL_ERROR;
    }

    if ( ( hostptr = gethostbyname( hostname ) ) == NULL )
    {
        Tcl_AppendResult( interp, "Error -- cannot get host info for node ",
            hostname, (char *) NULL );
        return TCL_ERROR;
    }

    Tcl_SetResult( interp,
        get_inet( hostptr->h_addr_list, hostptr->h_length ),
        TCL_VOLATILE );

    return TCL_OK;
}

#endif  // PLD_dp

//
//--------------------------------------------------------------------------
//
// pl_PacketReceive --
//
//      This procedure is a modified version of Tdp_PacketReceive,
//      from the Tcl-DP distribution.  It reads the socket,
//      returning a complete packet.  If the entire packet cannot
//      be read, the partial packet is buffered until the rest is
//      available.  Some capabilities have been removed from the
//      original, such as the check for a non-server TCP socket,
//      since there's no access to the optFlags array from here,
//      and the peek capability, since I don't need it.
//
// Results:
//      Packet contents stored in pdfs->buffer and pdfs->bp set
//      to the number of bytes read (zero if incomplete).
//
// Side effects:
//      The file descriptor passed in is read.
//
//--------------------------------------------------------------------------
//
int
pl_PacketReceive( Tcl_Interp *interp, PLiodev *iodev, PDFstrm *pdfs )
{
    int           j, numRead;
    unsigned int  packetLen, header[2];
    int           headerSize;
    unsigned char hbuf[8];
    const char    *errMsg;

    pdfs->bp = 0;

    //
    // Read in the header (8 bytes)
    //
    headerSize = 8;
    numRead    = pl_Read( iodev->fd, (char *) hbuf, headerSize );

    if ( numRead <= 0 )
    {
#ifdef DEBUG
        fprintf( stderr, "Incorrect header read, numRead = %d\n", numRead );
#endif
        goto readError;
    }

    //
    // Check for incomplete read.  If so, put it back and return.
    //
    if ( numRead < headerSize )
    {
#ifdef DEBUG
        fprintf( stderr, "Incomplete header read, numRead = %d\n", numRead );
#endif
        pl_Unread( iodev->fd, (char *) hbuf, numRead, 1 );
        Tcl_ResetResult( interp );
        return TCL_OK;
    }

    //
    // Convert header character stream into ints.  This works when the
    // connecting machine has a different size int and takes care of the
    // endian problem to boot.  It is also mostly backward compatible since
    // network byte ordering (big endian) is used.
    //

    j = 0;

    header[0]  = 0;
    header[0] |= (unsigned int) ( hbuf[j++] << 24 );
    header[0] |= (unsigned int) ( hbuf[j++] << 16 );
    header[0] |= (unsigned int) ( hbuf[j++] << 8 );
    header[0] |= hbuf[j++];

    header[1]  = 0;
    header[1] |= (unsigned int) ( hbuf[j++] << 24 );
    header[1] |= (unsigned int) ( hbuf[j++] << 16 );
    header[1] |= (unsigned int) ( hbuf[j++] << 8 );
    header[1] |= hbuf[j++];

    //
    // Format of each packet:
    //
    //          First 4 bytes are PACKET_MAGIC.
    //          Next 4 bytes are packetLen.
    //          Next packetLen-headerSize is zero terminated string
    //
    if ( header[0] != PACKET_MAGIC )
    {
        fprintf( stderr, "Badly formatted packet, numRead = %d\n", numRead );
        Tcl_AppendResult( interp, "Error reading from ", iodev->typeName,
            ": badly formatted packet", (char *) NULL );
        return TCL_ERROR;
    }
    packetLen = header[1] - (unsigned int) headerSize;

    //
    // Expand the size of the buffer, as needed.
    //

    if ( header[1] > (unsigned) pdfs->bufmax )
    {
        free( (void *) pdfs->buffer );
        pdfs->bufmax = header[1] + 32;
        pdfs->buffer = (unsigned char *) malloc( pdfs->bufmax );
    }

    //
    // Read in the packet, and if it's not all there, put it back.
    //
    // We have to be careful here, because we could block if just the
    // header came in (making the file readable at the beginning of this
    // function) but the rest of the packet is still out on the network.
    //

    if ( iodev->type == 0 )
    {
        numRead = pl_Read( iodev->fd, (char *) pdfs->buffer, (int) packetLen );
    }
    else
    {
#ifdef PLD_dp
        if ( Tdp_FDIsReady( iodev->fd ) & TCL_FILE_READABLE )
        {
            numRead = pl_Read( iodev->fd, (char *) pdfs->buffer, packetLen );
        }
        else
        {
#ifdef DEBUG
            fprintf( stderr, "Packet not ready, putting back header\n" );
#endif
            pl_Unread( iodev->fd, (char *) hbuf, headerSize, 1 );
            Tcl_ResetResult( interp );
            return TCL_OK;
        }
#endif
    }

    if ( numRead <= 0 )
    {
        goto readError;
    }

    if ( (unsigned) numRead != packetLen )
    {
#ifdef DEBUG
        fprintf( stderr, "Incomplete packet read, numRead = %d\n", numRead );
#endif
        pl_Unread( iodev->fd, (char *) pdfs->buffer, numRead, 1 );
        pl_Unread( iodev->fd, (char *) hbuf, headerSize, 1 );
        return TCL_OK;
    }

    pdfs->bp = (size_t) numRead;
#ifdef DEBUG
    fprintf( stderr, "received %d byte packet starting with:", numRead );
    for ( j = 0; j < 4; j++ )
    {
        fprintf( stderr, " %x", 0x000000FF & (unsigned long) pdfs->buffer[j] );
    }
    fprintf( stderr, "\n" );
#endif

    return TCL_OK;

readError:
    //
    //
    // If we're in non-blocking mode, and this would block, return.
    // If the connection is closed (numRead == 0), don't return an
    // error message.  Otherwise, return one.
    //
    // In either case, we close the file, delete the file handler, and
    // return a null string.
    //

    if ( errno == PLPLOT_EWOULDBLOCK || errno == EAGAIN )
    {
        Tcl_ResetResult( interp );
        return TCL_OK;
    }

    // Record the error before closing the file
    if ( numRead != 0 )
    {
        errMsg = Tcl_PosixError( interp );
    }
    else
    {
        errMsg = NULL;  // Suppresses spurious compiler warning
    }

    //
    // Remove the file handler and close the file.
    //
    if ( iodev->type == 0 )
    {
// Exclude UNIX-only feature
#if !defined ( MAC_TCL ) && !defined ( _WIN32 ) && !defined ( __CYGWIN__ )
        Tk_DeleteFileHandler( iodev->fd );
#endif
        close( iodev->fd );
    }
    pl_FreeReadBuffer( iodev->fd );

    Tcl_ResetResult( interp );
    if ( numRead == 0 )
    {
        return TCL_OK;
    }
    else
    {
        Tcl_AppendResult( interp, "pl_PacketReceive -- error reading from ",
            iodev->typeName, ": ", errMsg, (char *) NULL );
        return TCL_ERROR;
    }
}

//
//--------------------------------------------------------------------------
//
// pl_PacketSend --
//
//      This procedure is a modified version of Tdp_PacketSend,
//      from the Tcl-DP distribution.  It writes a complete packet
//      to a socket or file-oriented device.
//
// Results:
//      A standard tcl result.
//
// Side effects:
//      The specified buffer is written to the file descriptor passed
//      in.
//
//--------------------------------------------------------------------------
//

int
pl_PacketSend( Tcl_Interp * interp, PLiodev *iodev, PDFstrm *pdfs )
{
    int           j, numSent;
    unsigned char hbuf[8];
    unsigned int  packetLen, header[2];
    size_t        len;
    char          *buffer, tmp[256];

    //
    // Format up the packet:
    //    First 4 bytes are PACKET_MAGIC.
    //    Next 4 bytes are packetLen.
    //    Next packetLen-8 bytes are buffer contents.
    //

    packetLen = (unsigned int) pdfs->bp + 8;

    header[0] = PACKET_MAGIC;
    header[1] = packetLen;

    //
    // Convert header ints to character stream.
    // Network byte ordering (big endian) is used.
    //

    j = 0;

    hbuf[j++] = (unsigned char) ( ( header[0] & (unsigned long) 0xFF000000 ) >> 24 );
    hbuf[j++] = (unsigned char) ( ( header[0] & (unsigned long) 0x00FF0000 ) >> 16 );
    hbuf[j++] = (unsigned char) ( ( header[0] & (unsigned long) 0x0000FF00 ) >> 8 );
    hbuf[j++] = (unsigned char) ( header[0] & (unsigned long) 0x000000FF );

    hbuf[j++] = (unsigned char) ( ( header[1] & (unsigned long) 0xFF000000 ) >> 24 );
    hbuf[j++] = (unsigned char) ( ( header[1] & (unsigned long) 0x00FF0000 ) >> 16 );
    hbuf[j++] = (unsigned char) ( ( header[1] & (unsigned long) 0x0000FF00 ) >> 8 );
    hbuf[j++] = (unsigned char) ( header[1] & (unsigned long) 0x000000FF );

    //
    // Send it off, with error checking.
    // Simulate writev using memcpy to put together
    // the msg so it can go out in a single write() call.
    //

    len    = pdfs->bp + 8;
    buffer = (char *) malloc( len );

    memcpy( buffer, (char *) hbuf, 8 );
    memcpy( buffer + 8, (char *) pdfs->buffer, pdfs->bp );

#ifdef DEBUG
    fprintf( stderr, "sending  %z byte packet starting with:", len );
    for ( j = 0; j < 12; j++ )
    {
        fprintf( stderr, " %x", 0x000000FF & (unsigned long) buffer[j] );
    }
    fprintf( stderr, "\n" );
#endif
    numSent = (int) write( iodev->fd, buffer, len );

    free( buffer );

    if ( (unsigned) numSent != packetLen )
    {
        if ( ( errno == 0 ) || ( errno == PLPLOT_EWOULDBLOCK || errno == EAGAIN ) )
        {
            //
            // Non-blocking I/O: return number of bytes actually sent.
            //
            Tcl_ResetResult( interp );
            sprintf( tmp, "%d", numSent - 8 );
            Tcl_SetResult( interp, tmp, TCL_VOLATILE );
            return TCL_OK;
        }
        else if ( errno == EPIPE )
        {
            //
            // Got a broken pipe signal, which means the far end closed
            // the connection.  Close the file and return 0 bytes sent.
            //
            if ( iodev->type == 0 )
            {
                close( iodev->fd );
            }
            sprintf( tmp, "0" );
            Tcl_SetResult( interp, tmp, TCL_VOLATILE );
            return TCL_OK;
        }
        else
        {
            Tcl_AppendResult( interp, "pl_PacketSend -- error writing to ",
                iodev->typeName, ": ",
                Tcl_PosixError( interp ), (char *) NULL );
        }

        return TCL_ERROR;
    }

    //
    // Return the number of bytes sent (minus the header).
    //
    sprintf( tmp, "%d", numSent - 8 );
    Tcl_SetResult( interp, tmp, TCL_VOLATILE );
    return TCL_OK;
}

#else
int
pldummy_tcpip()
{
    return 0;
}

#endif  // defined(PLD_tk) || defined (ENABLE_tkX)