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[gnutls.git] / lib / gnutls_buffers.c

/*
 *      Copyright (C) 2000,2001,2002 Nikos Mavroyanopoulos
 *
 * This file is part of GNUTLS.
 *
 *  The GNUTLS library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public   
 *  License as published by the Free Software Foundation; either 
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 */

#include <gnutls_int.h>
#include <gnutls_errors.h>
#include <gnutls_num.h>
#include <gnutls_record.h>
#include <gnutls_buffers.h>
#include <gnutls_datum.h>

/* This is the only file that uses the berkeley sockets API.
 * 
 * Also holds all the buffering code used in gnutls.
 * The buffering code works as:
 *
 * RECORD LAYER: 
 *  1. uses a buffer to hold data (application/handshake),
 *    we got but they were not requested, yet.
 *  (see gnutls_record_buffer_put(), gnutls_record_buffer_get_size() etc.)
 *
 *  2. uses a buffer to hold data that were incomplete (ie the read/write
 *    was interrupted)
 *  (see _gnutls_io_read_buffered(), _gnutls_io_write_buffered() etc.)
 * 
 * HANDSHAKE LAYER:
 *  1. Uses a buffer to hold data that was not sent or received
 *  complete. (Ie. sent 10 bytes of a handshake packet that is 20 bytes
 *  long).
 * (see _gnutls_handshake_send_int(), _gnutls_handshake_recv_int())
 *
 *  2. Uses buffer to hold the last received handshake message.
 *  (see _gnutls_handshake_buffer_put() etc.)
 *
 */

#ifdef HAVE_ERRNO_H
# include <errno.h>
#endif

#ifndef EAGAIN
# define EAGAIN EWOULDBLOCK
#endif

inline 
static int RET( int err) {
        if (err==EAGAIN) return GNUTLS_E_AGAIN;
        return GNUTLS_E_INTERRUPTED;
}

#ifdef IO_DEBUG
# include <io_debug.h>
#endif

/* Buffers received packets of type APPLICATION DATA and
 * HANDSHAKE DATA.
 */
int _gnutls_record_buffer_put(ContentType type, GNUTLS_STATE state, char *data, int length)
{
        if (length==0) return 0;
        switch( type) {
        case GNUTLS_APPLICATION_DATA:

                if ( gnutls_datum_append( &state->gnutls_internals.application_data_buffer,
                        data, length) < 0) {
                        gnutls_assert();
                        return GNUTLS_E_MEMORY_ERROR;
                }
                _gnutls_buffers_log( "BUF[REC]: Inserted %d bytes of Data(%d)\n", length, type);

                break;
        case GNUTLS_HANDSHAKE:
                if ( gnutls_datum_append( &state->gnutls_internals.handshake_data_buffer,
                        data, length) < 0) {
                        gnutls_assert();
                        return GNUTLS_E_MEMORY_ERROR;
                }

                _gnutls_buffers_log( "BUF[HSK]: Inserted %d bytes of Data(%d)\n", length, type);

                break;
        
        default:
                gnutls_assert();
                return GNUTLS_E_INVALID_PARAMETERS;
        }

        return 0;

}

int _gnutls_record_buffer_get_size(ContentType type, GNUTLS_STATE state)
{
        switch( type) {
                case GNUTLS_APPLICATION_DATA:
                        return state->gnutls_internals.application_data_buffer.size;
        
                case GNUTLS_HANDSHAKE:
                        return state->gnutls_internals.handshake_data_buffer.size;
                
                default:
                        return GNUTLS_E_INVALID_PARAMETERS;
        }
        return 0;
}

/**
  * gnutls_record_check_pending - checks if there are any data to receive in gnutls buffers.
  * @state: is a &GNUTLS_STATE structure.
  *
  * This function checks if there are any data to receive
  * in the gnutls buffers. Returns the size of that data or 0.
  * Notice that you may also use select() to check for data in
  * the TCP connection, instead of this function.
  * (gnutls leaves some data in the tcp buffer in order for select
  * to work).
  **/
size_t gnutls_record_check_pending(GNUTLS_STATE state) {
        return _gnutls_record_buffer_get_size(GNUTLS_APPLICATION_DATA, state);
}

int _gnutls_record_buffer_get(ContentType type, GNUTLS_STATE state, char *data, int length)
{
        if (length < 0 || data==NULL) {
                gnutls_assert();
                return GNUTLS_E_INVALID_PARAMETERS;
        }
        
        switch(type) {
        case GNUTLS_APPLICATION_DATA:
        
                if (length > state->gnutls_internals.application_data_buffer.size) {
                        length = state->gnutls_internals.application_data_buffer.size;
                }

                _gnutls_buffers_log( "BUFFER[REC][AD]: Read %d bytes of Data(%d)\n", length, type);

                state->gnutls_internals.application_data_buffer.size -= length;
                memcpy(data, state->gnutls_internals.application_data_buffer.data, length);

                /* overwrite buffer */
                memmove(state->gnutls_internals.application_data_buffer.data,
                        &state->gnutls_internals.application_data_buffer.data[length],
                        state->gnutls_internals.application_data_buffer.size);

                /* this does not fail */
                state->gnutls_internals.application_data_buffer.data =
                    gnutls_realloc_fast(state->gnutls_internals.application_data_buffer.data,
                                   state->gnutls_internals.application_data_buffer.size);
                break;
                
        case GNUTLS_HANDSHAKE:
                if (length > state->gnutls_internals.handshake_data_buffer.size) {
                        length = state->gnutls_internals.handshake_data_buffer.size;
                }

                _gnutls_buffers_log( "BUF[REC][HD]: Read %d bytes of Data(%d)\n", length, type);

                state->gnutls_internals.handshake_data_buffer.size -= length;
                memcpy(data, state->gnutls_internals.handshake_data_buffer.data, length);

                /* overwrite buffer */
                memmove(state->gnutls_internals.handshake_data_buffer.data,
                        &state->gnutls_internals.handshake_data_buffer.data[length],
                        state->gnutls_internals.handshake_data_buffer.size);

                /* does not fail */
                state->gnutls_internals.handshake_data_buffer.data =
                    gnutls_realloc_fast(state->gnutls_internals.handshake_data_buffer.data,
                                   state->gnutls_internals.handshake_data_buffer.size);
                break;
        default:
                gnutls_assert();
                return GNUTLS_E_INVALID_PARAMETERS;
        }


        return length;
}


/* This function is like read. But it does not return -1 on error.
 * It does return gnutls_errno instead.
 *
 * Flags are only used if the default recv() function is being used.
 */
static ssize_t _gnutls_read( GNUTLS_STATE state, void *iptr, size_t sizeOfPtr, int flags)
{
        size_t left;
        ssize_t i=0;
        char *ptr = iptr;
#ifdef READ_DEBUG
        int j,x, sum=0;
#endif
        GNUTLS_TRANSPORT_PTR fd = state->gnutls_internals.transport_ptr;

        left = sizeOfPtr;
        while (left > 0) {
                
                if (state->gnutls_internals._gnutls_pull_func==NULL)
                        i = recv(fd, &ptr[sizeOfPtr-left], left, flags);
                else
                        i = state->gnutls_internals._gnutls_pull_func(fd, &ptr[sizeOfPtr-left], left);
                                
                if (i < 0) {
                        _gnutls_read_log( "READ: %d returned from %d, errno=%d\n", i, fd, errno);

                        if (errno == EAGAIN || errno == EINTR) {
                                if (sizeOfPtr-left > 0) {

                                        _gnutls_read_log( "READ: returning %d bytes from %d\n", sizeOfPtr-left, fd);

                                        goto finish;
                                }
                                gnutls_assert();

                                return RET(errno);
                        } else {
                                gnutls_assert();
                                return GNUTLS_E_PULL_ERROR;
                        }
                } else {

                        _gnutls_read_log( "READ: Got %d bytes from %d\n", i, fd);

                        if (i == 0)
                                break;  /* EOF */
                }

                left -= i;

        }

        finish:
        
#ifdef READ_DEBUG
        _gnutls_read_log( "READ: read %d bytes from %d\n", (sizeOfPtr-left), fd);
        for (x=0;x<((sizeOfPtr-left)/16)+1;x++) {
                _gnutls_read_log( "%.4x - ",x);
                for (j=0;j<16;j++) {
                        if (sum<(sizeOfPtr-left)) {
                                _gnutls_read_log( "%.2x ", ((unsigned char*)ptr)[sum++]);
                        }
                }
                _gnutls_read_log( "\n");
        
        }
#endif


        return (sizeOfPtr - left);
}


#define RCVLOWAT state->gnutls_internals.lowat 

/* This function is only used with berkeley style sockets.
 * Clears the peeked data (read with MSG_PEEK).
 */
int _gnutls_io_clear_peeked_data( GNUTLS_STATE state) {
char *peekdata = NULL;
int ret, sum;

        if (state->gnutls_internals.have_peeked_data==0 || RCVLOWAT==0)
                return 0;
                
        peekdata = gnutls_alloca( RCVLOWAT);
        if (peekdata==NULL) {
                gnutls_assert();
                return GNUTLS_E_MEMORY_ERROR;
        }
                
        /* this was already read by using MSG_PEEK - so it shouldn't fail */
        sum = 0;
        do { /* we need this to finish now */
                ret = _gnutls_read( state, peekdata, RCVLOWAT-sum, 0);
                if (ret > 0) sum+=ret;
        } while( ret==GNUTLS_E_INTERRUPTED || ret==GNUTLS_E_AGAIN || sum < RCVLOWAT);

        gnutls_afree(peekdata);
        
        if (ret < 0) {
                gnutls_assert();
                return ret;
        }

        state->gnutls_internals.have_peeked_data=0;

        return 0;
}


void _gnutls_io_clear_read_buffer( GNUTLS_STATE state) {
        state->gnutls_internals.record_recv_buffer.size = 0;
}
                        
/* This function is like recv(with MSG_PEEK). But it does not return -1 on error.
 * It does return gnutls_errno instead.
 * This function reads data from the socket and keeps them in a buffer, of up to
 * MAX_RECV_SIZE. 
 *
 * sizeOfPtr should be unsigned.
 *
 * This is not a general purpose function. It returns EXACTLY the data requested,
 * which are stored in a local (in the state) buffer. A pointer (iptr) to this buffer is returned.
 *
 */
ssize_t _gnutls_io_read_buffered( GNUTLS_STATE state, opaque **iptr, size_t sizeOfPtr, ContentType recv_type)
{
        ssize_t ret=0, ret2=0;
        int min, buf_pos;
        char *buf;
        int recvlowat = RCVLOWAT;
        int recvdata, alloc_size;

        *iptr = state->gnutls_internals.record_recv_buffer.data;

        if ( sizeOfPtr > MAX_RECV_SIZE || sizeOfPtr == 0 
        || (state->gnutls_internals.record_recv_buffer.size+sizeOfPtr) > MAX_RECV_SIZE) {
                gnutls_assert(); /* internal error */
                return GNUTLS_E_INVALID_PARAMETERS;
        }
        
        /* leave peeked data to the kernel space only if application data
         * is received and we don't have any peeked 
         * data in gnutls state.
         */
        if ( recv_type != GNUTLS_APPLICATION_DATA
                && state->gnutls_internals.have_peeked_data==0)
                recvlowat = 0;

        
        /* calculate the actual size, ie. get the minimum of the
         * buffered data and the requested data.
         */
        min = GMIN( state->gnutls_internals.record_recv_buffer.size, sizeOfPtr);
        if ( min > 0) {
                /* if we have enough buffered data
                 * then just return them.
                 */
                if ( min == sizeOfPtr) {
                        return min;
                }
        }

        /* min is over zero. recvdata is the data we must
         * receive in order to return the requested data.
         */
        recvdata = sizeOfPtr - min;
        
        /* Allocate the data required to store the new packet.
         */
         
        alloc_size = recvdata+state->gnutls_internals.record_recv_buffer.size;
        state->gnutls_internals.record_recv_buffer.data = gnutls_realloc_fast(
                state->gnutls_internals.record_recv_buffer.data, alloc_size);
        if ( state->gnutls_internals.record_recv_buffer.data==NULL) {
                gnutls_assert();
                return GNUTLS_E_MEMORY_ERROR;
        }

        buf_pos = state->gnutls_internals.record_recv_buffer.size;
        buf = state->gnutls_internals.record_recv_buffer.data;
        *iptr = buf;

        /* READ DATA - but leave RCVLOWAT bytes in the kernel buffer.
         */
        if ( recvdata - recvlowat > 0) {
                ret = _gnutls_read( state, &buf[buf_pos], recvdata - recvlowat, 0);

                /* return immediately if we got an interrupt or eagain
                 * error.
                 */
                if (ret < 0 && gnutls_error_is_fatal(ret)==0) {
                        return ret;
                }
        }

        /* copy fresh data to our buffer.
         */
        if (ret > 0) {
                _gnutls_read_log("RB: Have %d bytes into buffer. Adding %d bytes.\nRB: Requested %d bytes\n", state->gnutls_internals.record_recv_buffer.size, ret, sizeOfPtr);
                state->gnutls_internals.record_recv_buffer.size += ret;
        }

        buf_pos = state->gnutls_internals.record_recv_buffer.size;
        
        /* This is hack in order for select to work. Just leave recvlowat data,
         * into the kernel buffer (using a read with MSG_PEEK), thus making
         * select think, that the socket is ready for reading.
         * MSG_PEEK is only used with berkeley style sockets.
         */
        if (ret == (recvdata - recvlowat) && recvlowat > 0) {
                ret2 = _gnutls_read( state, &buf[buf_pos], recvlowat, MSG_PEEK);

                if (ret2 < 0 && gnutls_error_is_fatal(ret2)==0) {
                        return ret2;
                }

                if (ret2 > 0) {
                        _gnutls_read_log("RB-PEEK: Read %d bytes in PEEK MODE.\n", ret2); 
                        _gnutls_read_log("RB-PEEK: Have %d bytes into buffer. Adding %d bytes.\nRB: Requested %d bytes\n", state->gnutls_internals.record_recv_buffer.size, ret2, sizeOfPtr);
                        state->gnutls_internals.have_peeked_data = 1;
                        state->gnutls_internals.record_recv_buffer.size += ret2;

                }
        }

        if (ret < 0 || ret2 < 0) {
                gnutls_assert();
                /* that's because they are initilized to 0 */
                return GMIN(ret, ret2);
        }

        ret += ret2;

        if (ret > 0 && ret < recvlowat) {
                gnutls_assert();
                return GNUTLS_E_AGAIN;
        }
        
        if (ret==0) { /* EOF */
                gnutls_assert();
                return 0;
        }

        ret = state->gnutls_internals.record_recv_buffer.size;

        if ((ret > 0) && (ret < sizeOfPtr)) {
                /* Short Read */
                gnutls_assert();
                return GNUTLS_E_AGAIN;
        } else {
                return ret;
        }
}


/* These two functions are used to insert data to the send buffer of the handshake or
 * record protocol. The send buffer is kept if a send is interrupted and we need to keep
 * the data left to sent, in order to send them later.
 */
 
#define MEMSUB(x,y) (x-y)

inline
static int _gnutls_buffer_insert( gnutls_datum * buffer, const opaque* _data, int data_size) {

        if ( ( MEMSUB(_data, buffer->data) >= 0) && (MEMSUB(_data, buffer->data) < buffer->size) ) {
                /* the given _data is part of the buffer.
                 */
                if (data_size > buffer->size) {
                        gnutls_assert();
                        /* this shouldn't have happened */
                        return GNUTLS_E_UNKNOWN_ERROR;
                }
                
                if (_data==buffer->data) { /* then don't even memmove */
                        buffer->size = data_size;
                        return 0;
                }
                
                memmove( buffer->data, _data, data_size);
                buffer->size = data_size;

                return 0;               

        }

        buffer->data = gnutls_realloc_fast( buffer->data, data_size);
        buffer->size = data_size;
        
        if (buffer->data == NULL) {
                gnutls_assert();
                return GNUTLS_E_MEMORY_ERROR;
        }

        memcpy( buffer->data, _data, data_size);

        return 0;
}

inline
static int _gnutls_buffer_get( gnutls_datum * buffer, const opaque ** ptr, size_t *ptr_size) {
        *ptr_size = buffer->size;
        *ptr = buffer->data;
        
        return 0;
}


/* This function is like write. But it does not return -1 on error.
 * It does return gnutls_errno instead.
 *
 * In case of E_AGAIN and E_INTERRUPTED errors, you must call gnutls_write_flush(),
 * until it returns ok (0).
 *
 * We need to push exactly the data in n, since we cannot send less
 * data. In TLS the peer must receive the whole packet in order
 * to decrypt and verify the integrity. 
 *
 */
ssize_t _gnutls_io_write_buffered( GNUTLS_STATE state, const void *iptr, size_t n)
{
        size_t left;
#ifdef WRITE_DEBUG
        int j,x, sum=0;
#endif
        ssize_t retval, i;
        const opaque * ptr;
        int ret;
        GNUTLS_TRANSPORT_PTR fd = state->gnutls_internals.transport_ptr;
        
        ptr = iptr;

        /* In case the previous write was interrupted, check if the
         * iptr != NULL and we have data in the buffer.
         * If this is true then return an error.
         */
        if (state->gnutls_internals.record_send_buffer.size > 0 && iptr != NULL) {
                gnutls_assert();
                return GNUTLS_E_INVALID_PARAMETERS;
        }

        /* If data in the buffer exist
         */
        if (iptr == NULL) {
                /* checking is handled above */
                ret = _gnutls_buffer_get( &state->gnutls_internals.record_send_buffer, &ptr, &n);
                if (ret < 0) {
                        gnutls_assert();
                        return retval;
                }

                _gnutls_write_log( "WRITE: Restoring old write. (%d bytes to send)\n", n);
        }

        _gnutls_write_log( "WRITE: Will write %d bytes to %d.\n", n, fd);

        i = 0;
        left = n;
        while (left > 0) {
                
                if (state->gnutls_internals._gnutls_push_func==NULL) 
                        i = send(fd, &ptr[n-left], left, 0);
                else
                        i = state->gnutls_internals._gnutls_push_func(fd, &ptr[n-left], left);

                if (i == -1) {
                        if (errno == EAGAIN || errno == EINTR) {
                                state->gnutls_internals.record_send_buffer_prev_size += n - left;

                                retval = _gnutls_buffer_insert( &state->gnutls_internals.record_send_buffer, &ptr[n-left], left);
                                if (retval < 0) {
                                        gnutls_assert();
                                        return retval;
                                }
                                
                                _gnutls_write_log( "WRITE: Interrupted. Stored %d bytes to buffer. Already sent %d bytes.\n", left, n-left);

                                retval = RET(errno);

                                return retval;
                        } else {
                                gnutls_assert();
                                return GNUTLS_E_PUSH_ERROR;
                        }
                }
                left -= i;

#ifdef WRITE_DEBUG
                _gnutls_write_log( "WRITE: wrote %d bytes to %d. Left %d bytes. Total %d bytes.\n", i, fd, left, n);
                for (x=0;x<((i)/16)+1;x++) {
                        if (sum>n-left)
                                break;

                        _gnutls_write_log( "%.4x - ",x);
                        for (j=0;j<16;j++) {
                                if (sum<n-left) {
                                        _gnutls_write_log( "%.2x ", ((unsigned char*)ptr)[sum++]);
                                } else break;
                        }
                        _gnutls_write_log( "\n");
                }
                _gnutls_write_log( "\n");
#endif

        }

        retval = n + state->gnutls_internals.record_send_buffer_prev_size;

        state->gnutls_internals.record_send_buffer.size = 0;
        state->gnutls_internals.record_send_buffer_prev_size = 0;

        return retval;

}

/* This is exactly like write_buffered, but will use two buffers to read
 * from.
 */
ssize_t _gnutls_io_write_buffered2( GNUTLS_STATE state, const void *iptr, size_t n, const void* iptr2, size_t n2)
{

        if (n==0) {
                return _gnutls_io_write_buffered( state, iptr2, n2);
        } else {
                opaque* sptr;
                ssize_t ret;

                sptr = gnutls_alloca( n+n2);
                if (sptr==NULL) {
                        gnutls_assert();
                        return GNUTLS_E_MEMORY_ERROR;
                }
        
                memcpy( sptr, iptr, n);
                memcpy( &sptr[n], iptr2, n2);

                ret = _gnutls_io_write_buffered( state, sptr, n+n2);
                gnutls_afree( sptr);

                return ret;
        }
}


/* This function writes the data that are left in the
 * TLS write buffer (ie. because the previous write was
 * interrupted.
 */
ssize_t _gnutls_io_write_flush( GNUTLS_STATE state)
{
    ssize_t ret;

    if (state->gnutls_internals.record_send_buffer.size == 0)
        return 0; /* done */

    ret = _gnutls_io_write_buffered( state, NULL, 0);
    _gnutls_write_log("WRITE FLUSH: %d [buffer: %d]\n", ret, state->gnutls_internals.record_send_buffer.size);

    return ret;
}

/* This function writes the data that are left in the
 * Handshake write buffer (ie. because the previous write was
 * interrupted.
 */
ssize_t _gnutls_handshake_io_write_flush( GNUTLS_STATE state)
{
    ssize_t ret;
    ret = _gnutls_handshake_io_send_int( state, 0, 0, NULL, 0);
    if (ret < 0) {
        gnutls_assert();
        return ret;
    }

    _gnutls_write_log("HANDSHAKE_FLUSH: written[1] %d bytes\n", ret);

    if (state->gnutls_internals.handshake_send_buffer.size == 0) {
        ret = state->gnutls_internals.handshake_send_buffer_prev_size; /* done */
        state->gnutls_internals.handshake_send_buffer_prev_size = 0;
        state->gnutls_internals.handshake_send_buffer.size = 0;

        return ret;
    }

    return ret;
}


/* This is a send function for the gnutls handshake 
 * protocol. Just makes sure that all data have been sent.
 */
ssize_t _gnutls_handshake_io_send_int( GNUTLS_STATE state, ContentType type, HandshakeType htype, const void *iptr, size_t n)
{
        size_t left;
        ssize_t i = 0, ret=0;
        const opaque *ptr;
        ssize_t retval = 0;

        ptr = iptr;
       
        if (state->gnutls_internals.handshake_send_buffer.size > 0 && ptr==NULL && n == 0) {
                /* resuming previously interrupted write
                 */
                gnutls_assert(); 
                ret = _gnutls_buffer_get( &state->gnutls_internals.handshake_send_buffer, &ptr, &n);
                if (ret < 0) {
                        gnutls_assert();
                        return retval;
                }

                type = state->gnutls_internals.handshake_send_buffer_type;
                htype = state->gnutls_internals.handshake_send_buffer_htype;

        } else if (state->gnutls_internals.handshake_send_buffer.size > 0) {
                gnutls_assert();
                return GNUTLS_E_UNKNOWN_ERROR;
        } else {
#ifdef WRITE_DEBUG
                size_t sum=0, x, j;
                
                _gnutls_write_log( "HWRITE: will write %d bytes to %d.\n", n, gnutls_transport_get_ptr(state));
                for (x=0;x<((n)/16)+1;x++) {
                        if (sum>n)
                                break;

                        _gnutls_write_log( "%.4x - ",x);
                        for (j=0;j<16;j++) {
                                if (sum<n) {
                                        _gnutls_write_log( "%.2x ", ((unsigned char*)ptr)[sum++]);
                                } else break;
                        }
                        _gnutls_write_log( "\n");
                }
                _gnutls_write_log( "\n");
#endif

        
        }

        if (n==0) { /* if we have no data to send */
                gnutls_assert();
                return 0;
        } else if (ptr==NULL) {
                gnutls_assert();
                return GNUTLS_E_UNKNOWN_ERROR;
        }
        

        left = n;
        while (left > 0) {
                ret = gnutls_send_int( state, type, htype, &ptr[n-left], left);

                if (ret <= 0) {
                        if (ret==0) {
                                gnutls_assert();
                                ret = GNUTLS_E_UNKNOWN_ERROR;
                        }

                        if ( left > 0 && (ret==GNUTLS_E_INTERRUPTED || ret==GNUTLS_E_AGAIN)) { 
                                gnutls_assert();

                                retval = _gnutls_buffer_insert( &state->gnutls_internals.handshake_send_buffer, &ptr[n-left], left);
                                if (retval < 0) {
                                        gnutls_assert();
                                        return retval;
                                }

                                state->gnutls_internals.handshake_send_buffer_prev_size += n-left;

                                state->gnutls_internals.handshake_send_buffer_type = type;
                                state->gnutls_internals.handshake_send_buffer_htype = htype;

                        } else {
                                state->gnutls_internals.handshake_send_buffer_prev_size = 0;
                                state->gnutls_internals.handshake_send_buffer.size = 0;
                        }

                        gnutls_assert();
                        return ret;
                }
                i = ret;
                left -= i;
        }

        retval = n + state->gnutls_internals.handshake_send_buffer_prev_size;

        state->gnutls_internals.handshake_send_buffer.size = 0;
        state->gnutls_internals.handshake_send_buffer_prev_size = 0;

        return retval;

}

/* This is a receive function for the gnutls handshake 
 * protocol. Makes sure that we have received all data.
 */
ssize_t _gnutls_handshake_io_recv_int( GNUTLS_STATE state, ContentType type, HandshakeType htype, void *iptr, size_t sizeOfPtr)
{
        size_t left;
        ssize_t i;
        char *ptr;
        size_t dsize;
                
        ptr = iptr;
        left = sizeOfPtr;

        if (sizeOfPtr == 0 || iptr == NULL) {
                gnutls_assert();
                return GNUTLS_E_INVALID_PARAMETERS;
        }

        if (state->gnutls_internals.handshake_recv_buffer.size > 0) {
                /* if we have already received some data */
                if (sizeOfPtr <= state->gnutls_internals.handshake_recv_buffer.size) {
                        /* if requested less data then return it.
                         */
                        gnutls_assert();
                        memcpy( iptr, state->gnutls_internals.handshake_recv_buffer.data, sizeOfPtr);

                        state->gnutls_internals.handshake_recv_buffer.size -= sizeOfPtr;

                        memmove( state->gnutls_internals.handshake_recv_buffer.data, 
                                &state->gnutls_internals.handshake_recv_buffer.data[sizeOfPtr], 
                                state->gnutls_internals.handshake_recv_buffer.size);
                        
                        return sizeOfPtr;
                }
                gnutls_assert();
                memcpy( iptr, state->gnutls_internals.handshake_recv_buffer.data, state->gnutls_internals.handshake_recv_buffer.size);

                htype = state->gnutls_internals.handshake_recv_buffer_htype;
                type = state->gnutls_internals.handshake_recv_buffer_type;

                left -= state->gnutls_internals.handshake_recv_buffer.size;

                state->gnutls_internals.handshake_recv_buffer.size = 0;
        }
        
        while (left > 0) {
                dsize = sizeOfPtr - left;
                i = gnutls_recv_int( state, type, htype, &ptr[dsize], left);
                if (i < 0) {
                        
                        if (dsize > 0 && (i==GNUTLS_E_INTERRUPTED || i==GNUTLS_E_AGAIN)) {
                                gnutls_assert();

                                state->gnutls_internals.handshake_recv_buffer.data = gnutls_realloc_fast(
                                        state->gnutls_internals.handshake_recv_buffer.data, dsize);
                                if (state->gnutls_internals.handshake_recv_buffer.data==NULL) {
                                        gnutls_assert();
                                        return GNUTLS_E_MEMORY_ERROR;
                                }
                                                        
                                memcpy( state->gnutls_internals.handshake_recv_buffer.data, iptr, dsize);

                                state->gnutls_internals.handshake_recv_buffer_htype = htype;
                                state->gnutls_internals.handshake_recv_buffer_type = type;

                                state->gnutls_internals.handshake_recv_buffer.size = dsize;
                        } else 
                                state->gnutls_internals.handshake_recv_buffer.size = 0;

                        gnutls_assert();

                        return i;
                } else {
                        if (i == 0)
                                break;  /* EOF */
                }

                left -= i;

        }

        state->gnutls_internals.handshake_recv_buffer.size = 0;

        return sizeOfPtr - left;
}

/* Buffer for handshake packets. Keeps the packets in order
 * for finished messages to use them. Used in HMAC calculation
 * and finished messages.
 */
int _gnutls_handshake_buffer_put( GNUTLS_STATE state, char *data, int length)
{

        if (length==0) return 0;        

        if ( (state->gnutls_internals.max_handshake_data_buffer_size > 0) &&
                ((length+state->gnutls_internals.handshake_hash_buffer.size) >
                        state->gnutls_internals.max_handshake_data_buffer_size)) {
                gnutls_assert();
                return GNUTLS_E_MEMORY_ERROR;
        }
        
        _gnutls_buffers_log( "BUF[HSK]: Inserted %d bytes of Data\n", length);

        if ( gnutls_datum_append( &state->gnutls_internals.handshake_hash_buffer,
                data, length) < 0) {
                gnutls_assert();
                return GNUTLS_E_MEMORY_ERROR;
        }

        return 0;
}

int _gnutls_handshake_buffer_get_size( GNUTLS_STATE state)
{

        return state->gnutls_internals.handshake_hash_buffer.size;
}

/* this function does not touch the buffer
 * and returns data from it (peek mode!)
 */
int _gnutls_handshake_buffer_peek( GNUTLS_STATE state, char *data, int length)
{
        if (length > state->gnutls_internals.handshake_hash_buffer.size) {
                length = state->gnutls_internals.handshake_hash_buffer.size;
        }

        _gnutls_buffers_log( "BUF[HSK]: Peeked %d bytes of Data\n", length);

        memcpy(data, state->gnutls_internals.handshake_hash_buffer.data, length);
        return length;  
}

/* this function does not touch the buffer
 * and returns data from it (peek mode!)
 */
int _gnutls_handshake_buffer_get_ptr( GNUTLS_STATE state, char **data_ptr, int *length)
{
        if (length!=NULL)
                *length = state->gnutls_internals.handshake_hash_buffer.size;

        _gnutls_buffers_log( "BUF[HSK]: Peeded %d bytes of Data\n", length);

        if (data_ptr!=NULL)
                *data_ptr = state->gnutls_internals.handshake_hash_buffer.data;

        return 0;       
}

/* Does not free the buffer
 */
int _gnutls_handshake_buffer_empty( GNUTLS_STATE state)
{

        _gnutls_buffers_log( "BUF[HSK]: Emptied buffer\n");

        state->gnutls_internals.handshake_hash_buffer.size = 0;
        
        return 0;
}


int _gnutls_handshake_buffer_clear( GNUTLS_STATE state)
{

        _gnutls_buffers_log( "BUF[HSK]: Cleared Data from buffer\n");

        state->gnutls_internals.handshake_hash_buffer.size = 0;
        if (state->gnutls_internals.handshake_hash_buffer.data!=NULL)
                gnutls_free(state->gnutls_internals.handshake_hash_buffer.data);
        state->gnutls_internals.handshake_hash_buffer.data = NULL;
        
        return 0;
}