source: rtems/cpukit/librpc/src/xdr/xdr_rec.c @ 9d1596d6

/*
 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
 * unrestricted use provided that this legend is included on all tape
 * media and as a part of the software program in whole or part.  Users
 * may copy or modify Sun RPC without charge, but are not authorized
 * to license or distribute it to anyone else except as part of a product or
 * program developed by the user.
 *
 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
 *
 * Sun RPC is provided with no support and without any obligation on the
 * part of Sun Microsystems, Inc. to assist in its use, correction,
 * modification or enhancement.
 *
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
 * OR ANY PART THEREOF.
 *
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 * or profits or other special, indirect and consequential damages, even if
 * Sun has been advised of the possibility of such damages.
 *
 * Sun Microsystems, Inc.
 * 2550 Garcia Avenue
 * Mountain View, California  94043
 */
#if defined(LIBC_SCCS) && !defined(lint)
/*static char *sccsid = "from: @(#)xdr_rec.c 1.21 87/08/11 Copyr 1984 Sun Micro";*/
/*static char *sccsid = "from: @(#)xdr_rec.c    2.2 88/08/01 4.0 RPCSRC";*/
static char *rcsid = "$FreeBSD: src/lib/libc/xdr/xdr_rec.c,v 1.12 2000/01/19 06:12:32 wpaul Exp $";
#endif

/*
 * xdr_rec.c, Implements TCP/IP based XDR streams with a "record marking"
 * layer above tcp (for rpc's use).
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 *
 * These routines interface XDRSTREAMS to a tcp/ip connection.
 * There is a record marking layer between the xdr stream
 * and the tcp transport level.  A record is composed on one or more
 * record fragments.  A record fragment is a thirty-two bit header followed
 * by n bytes of data, where n is contained in the header.  The header
 * is represented as a htonl(u_long).  Thegh order bit encodes
 * whether or not the fragment is the last fragment of the record
 * (1 => fragment is last, 0 => more fragments to follow.
 * The other 31 bits encode the byte length of the fragment.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <rpc/types.h>
#include <rpc/xdr.h>
#include <netinet/in.h>
#include <unistd.h>   /* for lseek() */

static u_int    fix_buf_size();
static bool_t   flush_out();
static bool_t   get_input_bytes();
static bool_t   set_input_fragment();
static bool_t   skip_input_bytes();

static bool_t   xdrrec_getlong();
static bool_t   xdrrec_putlong();
static bool_t   xdrrec_getbytes();
static bool_t   xdrrec_putbytes();
static u_int    xdrrec_getpos();
static bool_t   xdrrec_setpos();
static int32_t *xdrrec_inline();
static void     xdrrec_destroy();

static struct  xdr_ops xdrrec_ops = {
        xdrrec_getlong,
        xdrrec_putlong,
        xdrrec_getbytes,
        xdrrec_putbytes,
        xdrrec_getpos,
        xdrrec_setpos,
        xdrrec_inline,
        xdrrec_destroy
};

/*
 * A record is composed of one or more record fragments.
 * A record fragment is a two-byte header followed by zero to
 * 2**32-1 bytes.  The header is treated as a long unsigned and is
 * encode/decoded to the network via htonl/ntohl.  The low order 31 bits
 * are a byte count of the fragment.  The highest order bit is a boolean:
 * 1 => this fragment is the last fragment of the record,
 * 0 => this fragment is followed by more fragment(s).
 *
 * The fragment/record machinery is not general;  it is constructed to
 * meet the needs of xdr and rpc based on tcp.
 */

#define LAST_FRAG ((u_int32_t)(1L << 31))

typedef struct rec_strm {
        caddr_t tcp_handle;
        caddr_t the_buffer;
        /*
         * out-goung bits
         */
        int (*writeit) (caddr_t, caddr_t, int);
        caddr_t out_base;       /* output buffer (points to frag header) */
        caddr_t out_finger;     /* next output position */
        caddr_t out_boundry;    /* data cannot up to this address */
        u_int32_t *frag_header; /* beginning of current fragment */
        bool_t frag_sent;       /* true if buffer sent in middle of record */
        /*
         * in-coming bits
         */
        int (*readit) (caddr_t, caddr_t, int);
        u_long in_size; /* fixed size of the input buffer */
        caddr_t in_base;
        caddr_t in_finger;      /* location of next byte to be had */
        caddr_t in_boundry;     /* can read up to this location */
        long fbtbc;             /* fragment bytes to be consumed */
        bool_t last_frag;
        u_int sendsize;
        u_int recvsize;
} RECSTREAM;


/*
 * Create an xdr handle for xdrrec
 * xdrrec_create fills in xdrs.  Sendsize and recvsize are
 * send and recv buffer sizes (0 => use default).
 * tcp_handle is an opaque handle that is passed as the first parameter to
 * the procedures readit and writeit.  Readit and writeit are read and
 * write respectively.   They are like the system
 * calls expect that they take an opaque handle rather than an fd.
 */
void
xdrrec_create(
        XDR *xdrs,
        u_int sendsize,
        u_int recvsize,
        caddr_t tcp_handle,
        int (*readit)(char*, char*, int),  /* like read, but pass it a tcp_handle, not sock */
        int (*writeit)(char*, char*, int)  /* like write, but pass it a tcp_handle, not sock */
)
{
        register RECSTREAM *rstrm =
                (RECSTREAM *)mem_alloc(sizeof(RECSTREAM));

        if (rstrm == NULL) {
                (void)fprintf(stderr, "xdrrec_create: out of memory\n");
                /*
                 *  This is bad.  Should rework xdrrec_create to
                 *  return a handle, and in this case return NULL
                 */
                return;
        }
        /*
         * adjust sizes and allocate buffer quad byte aligned
         */
        rstrm->sendsize = sendsize = fix_buf_size(sendsize);
        rstrm->recvsize = recvsize = fix_buf_size(recvsize);
        rstrm->the_buffer = mem_alloc(sendsize + recvsize + BYTES_PER_XDR_UNIT);
        if (rstrm->the_buffer == NULL) {
                (void)fprintf(stderr, "xdrrec_create: out of memory\n");
                return;
        }
        for (rstrm->out_base = rstrm->the_buffer;
                (uintptr_t)rstrm->out_base % BYTES_PER_XDR_UNIT != 0;
                rstrm->out_base++);
        rstrm->in_base = rstrm->out_base + sendsize;
        /*
         * now the rest ...
         */
        xdrs->x_ops = &xdrrec_ops;
        xdrs->x_private = (caddr_t)rstrm;
        rstrm->tcp_handle = tcp_handle;
        rstrm->readit = readit;
        rstrm->writeit = writeit;
        rstrm->out_finger = rstrm->out_boundry = rstrm->out_base;
        rstrm->frag_header = (u_int32_t *)rstrm->out_base;
        rstrm->out_finger += sizeof(u_int32_t);
        rstrm->out_boundry += sendsize;
        rstrm->frag_sent = FALSE;
        rstrm->in_size = recvsize;
        rstrm->in_boundry = rstrm->in_base;
        rstrm->in_finger = (rstrm->in_boundry += recvsize);
        rstrm->fbtbc = 0;
        rstrm->last_frag = TRUE;
}


/*
 * The reoutines defined below are the xdr ops which will go into the
 * xdr handle filled in by xdrrec_create.
 */

static bool_t
xdrrec_getlong(
        XDR *xdrs,
        long *lp)
{
        register RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
        register int32_t *buflp = (int32_t *)(rstrm->in_finger);
        int32_t mylong;

        /* first try the inline, fast case */
        if ((rstrm->fbtbc >= sizeof(int32_t)) &&
                (((intptr_t)rstrm->in_boundry - (intptr_t)buflp) >= sizeof(int32_t))) {
                *lp = (long)ntohl((u_int32_t)(*buflp));
                rstrm->fbtbc -= sizeof(int32_t);
                rstrm->in_finger += sizeof(int32_t);
        } else {
                if (! xdrrec_getbytes(xdrs, (caddr_t)&mylong, sizeof(int32_t)))
                        return (FALSE);
                *lp = (long)ntohl((u_int32_t)mylong);
        }
        return (TRUE);
}

static bool_t
xdrrec_putlong(
        XDR *xdrs,
        long *lp)
{
        register RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
        register int32_t *dest_lp = ((int32_t *)(rstrm->out_finger));

        if ((rstrm->out_finger += sizeof(int32_t)) > rstrm->out_boundry) {
                /*
                 * this case should almost never happen so the code is
                 * inefficient
                 */
                rstrm->out_finger -= sizeof(int32_t);
                rstrm->frag_sent = TRUE;
                if (! flush_out(rstrm, FALSE))
                        return (FALSE);
                dest_lp = ((int32_t *)(rstrm->out_finger));
                rstrm->out_finger += sizeof(int32_t);
        }
        *dest_lp = (int32_t)htonl((u_int32_t)(*lp));
        return (TRUE);
}

static bool_t  /* must manage buffers, fragments, and records */
xdrrec_getbytes(
        XDR *xdrs,
        register caddr_t addr,
        register u_int len)
{
        register RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
        register int current;

        while (len > 0) {
                current = rstrm->fbtbc;
                if (current == 0) {
                        if (rstrm->last_frag)
                                return (FALSE);
                        if (! set_input_fragment(rstrm))
                                return (FALSE);
                        continue;
                }
                current = (len < current) ? len : current;
                if (! get_input_bytes(rstrm, addr, current))
                        return (FALSE);
                addr += current;
                rstrm->fbtbc -= current;
                len -= current;
        }
        return (TRUE);
}

static bool_t
xdrrec_putbytes(
        XDR *xdrs,
        caddr_t addr,
        u_int len)
{
        register RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
        register long current;

        while (len > 0) {
                current = (intptr_t)rstrm->out_boundry -
                        (intptr_t)rstrm->out_finger;
                current = (len < current) ? len : current;
                memcpy(rstrm->out_finger, addr, current);
                rstrm->out_finger += current;
                addr += current;
                len -= current;
                if (rstrm->out_finger == rstrm->out_boundry) {
                        rstrm->frag_sent = TRUE;
                        if (! flush_out(rstrm, FALSE))
                                return (FALSE);
                }
        }
        return (TRUE);
}

static u_int
xdrrec_getpos(
        XDR *xdrs)
{
        register RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
        register long pos;

        pos = lseek((intptr_t)rstrm->tcp_handle, (off_t) 0, 1);
        if (pos != -1)
                switch (xdrs->x_op) {

                case XDR_ENCODE:
                        pos += rstrm->out_finger - rstrm->out_base;
                        break;

                case XDR_DECODE:
                        pos -= rstrm->in_boundry - rstrm->in_finger;
                        break;

                default:
                        pos = -1;
                        break;
                }
        return ((u_int) pos);
}

static bool_t
xdrrec_setpos(
        XDR *xdrs,
        u_int pos)
{
        register RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
        u_int currpos = xdrrec_getpos(xdrs);
        int delta = currpos - pos;
        caddr_t newpos;

        if ((int)currpos != -1)
                switch (xdrs->x_op) {

                case XDR_ENCODE:
                        newpos = rstrm->out_finger - delta;
                        if ((newpos > (caddr_t)(rstrm->frag_header)) &&
                                (newpos < rstrm->out_boundry)) {
                                rstrm->out_finger = newpos;
                                return (TRUE);
                        }
                        break;

                case XDR_DECODE:
                        newpos = rstrm->in_finger - delta;
                        if ((delta < (int)(rstrm->fbtbc)) &&
                                (newpos <= rstrm->in_boundry) &&
                                (newpos >= rstrm->in_base)) {
                                rstrm->in_finger = newpos;
                                rstrm->fbtbc -= delta;
                                return (TRUE);
                        }
                        break;
                case XDR_FREE:  /* to avoid warning */
                        break;
                }
        return (FALSE);
}

static int32_t *
xdrrec_inline(
        XDR *xdrs,
        int len)
{
        register RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
        int32_t * buf = NULL;

        switch (xdrs->x_op) {

        case XDR_ENCODE:
                if ((rstrm->out_finger + len) <= rstrm->out_boundry) {
                        buf = (int32_t *) rstrm->out_finger;
                        rstrm->out_finger += len;
                }
                break;

        case XDR_DECODE:
                if ((len <= rstrm->fbtbc) &&
                        ((rstrm->in_finger + len) <= rstrm->in_boundry)) {
                        buf = (int32_t *) rstrm->in_finger;
                        rstrm->fbtbc -= len;
                        rstrm->in_finger += len;
                }
                break;
        case XDR_FREE:  /* to avoid warning */
                break;
        }
        return (buf);
}

static void
xdrrec_destroy(
        XDR *xdrs)
{
        register RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;

        mem_free(rstrm->the_buffer,
                rstrm->sendsize + rstrm->recvsize + BYTES_PER_XDR_UNIT);
        mem_free((caddr_t)rstrm, sizeof(RECSTREAM));
}


/*
 * Exported routines to manage xdr records
 */

/*
 * Before reading (deserializing from the stream, one should always call
 * this procedure to guarantee proper record alignment.
 */
bool_t
xdrrec_skiprecord(
        XDR *xdrs)
{
        register RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);

        while (rstrm->fbtbc > 0 || (! rstrm->last_frag)) {
                if (! skip_input_bytes(rstrm, rstrm->fbtbc))
                        return (FALSE);
                rstrm->fbtbc = 0;
                if ((! rstrm->last_frag) && (! set_input_fragment(rstrm)))
                        return (FALSE);
        }
        rstrm->last_frag = FALSE;
        return (TRUE);
}

/*
 * Look ahead fuction.
 * Returns TRUE iff there is no more input in the buffer
 * after consuming the rest of the current record.
 */
bool_t
xdrrec_eof(
        XDR *xdrs)
{
        register RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);

        while (rstrm->fbtbc > 0 || (! rstrm->last_frag)) {
                if (! skip_input_bytes(rstrm, rstrm->fbtbc))
                        return (TRUE);
                rstrm->fbtbc = 0;
                if ((! rstrm->last_frag) && (! set_input_fragment(rstrm)))
                        return (TRUE);
        }
        if (rstrm->in_finger == rstrm->in_boundry)
                return (TRUE);
        return (FALSE);
}

/*
 * The client must tell the package when an end-of-record has occurred.
 * The second paraemters tells whether the record should be flushed to the
 * (output) tcp stream.  (This let's the package support batched or
 * pipelined procedure calls.)  TRUE => immmediate flush to tcp connection.
 */
bool_t
xdrrec_endofrecord(
        XDR *xdrs,
        bool_t sendnow)
{
        register RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
        register u_long len;  /* fragment length */

        if (sendnow || rstrm->frag_sent ||
                ((uintptr_t)rstrm->out_finger + sizeof(u_int32_t) >=
                (uintptr_t)rstrm->out_boundry)) {
                rstrm->frag_sent = FALSE;
                return (flush_out(rstrm, TRUE));
        }
        len = (uintptr_t)(rstrm->out_finger) - (uintptr_t)(rstrm->frag_header) -
           sizeof(u_int32_t);
        *(rstrm->frag_header) = htonl((u_int32_t)len | LAST_FRAG);
        rstrm->frag_header = (u_int32_t *)rstrm->out_finger;
        rstrm->out_finger += sizeof(u_int32_t);
        return (TRUE);
}


/*
 * Internal useful routines
 */
static bool_t
flush_out(
        RECSTREAM *rstrm,
        bool_t eor)
{
        register u_int32_t eormask = (eor == TRUE) ? LAST_FRAG : 0;
        register u_int32_t len = (uintptr_t)(rstrm->out_finger) -
                (uintptr_t)(rstrm->frag_header) - sizeof(u_int32_t);

        *(rstrm->frag_header) = htonl(len | eormask);
        len = (uintptr_t)(rstrm->out_finger) - (uintptr_t)(rstrm->out_base);
        if ((*(rstrm->writeit))(rstrm->tcp_handle, rstrm->out_base, (int)len)
                != (int)len)
                return (FALSE);
        rstrm->frag_header = (u_int32_t *)rstrm->out_base;
        rstrm->out_finger = (caddr_t)rstrm->out_base + sizeof(u_int32_t);
        return (TRUE);
}

static bool_t  /* knows nothing about records!  Only about input buffers */
fill_input_buf(
        RECSTREAM *rstrm)
{
        register caddr_t where;
        u_long i;
        register long len;

        where = rstrm->in_base;
        i = (uintptr_t)rstrm->in_boundry % BYTES_PER_XDR_UNIT;
        where += i;
        len = rstrm->in_size - i;
        if ((len = (*(rstrm->readit))(rstrm->tcp_handle, where, len)) == -1)
                return (FALSE);
        rstrm->in_finger = where;
        where += len;
        rstrm->in_boundry = where;
        return (TRUE);
}

static bool_t  /* knows nothing about records!  Only about input buffers */
get_input_bytes(
        RECSTREAM *rstrm,
        caddr_t addr,
        int len)
{
        register long current;

        while (len > 0) {
                current = (intptr_t)rstrm->in_boundry - (intptr_t)rstrm->in_finger;
                if (current == 0) {
                        if (! fill_input_buf(rstrm))
                                return (FALSE);
                        continue;
                }
                current = (len < current) ? len : current;
                memcpy(addr, rstrm->in_finger, current);
                rstrm->in_finger += current;
                addr += current;
                len -= current;
        }
        return (TRUE);
}

static bool_t  /* next two bytes of the input stream are treated as a header */
set_input_fragment(
        RECSTREAM *rstrm)
{
        u_int32_t header;

        if (! get_input_bytes(rstrm, (caddr_t)&header, sizeof(header)))
                return (FALSE);
        header = (long)ntohl(header);
        rstrm->last_frag = ((header & LAST_FRAG) == 0) ? FALSE : TRUE;
        /*
         * Sanity check. Try not to accept wildly incorrect
         * record sizes. Unfortunately, the only record size
         * we can positively identify as being 'wildly incorrect'
         * is zero. Ridiculously large record sizes may look wrong,
         * but we don't have any way to be certain that they aren't
         * what the client actually intended to send us.
         */
        if (header == 0)
                return(FALSE);
        rstrm->fbtbc = header & (~LAST_FRAG);
        return (TRUE);
}

static bool_t  /* consumes input bytes; knows nothing about records! */
skip_input_bytes(
        RECSTREAM *rstrm,
        long cnt)
{
        register long current;

        while (cnt > 0) {
                current = (intptr_t)rstrm->in_boundry - (intptr_t)rstrm->in_finger;
                if (current == 0) {
                        if (! fill_input_buf(rstrm))
                                return (FALSE);
                        continue;
                }
                current = (cnt < current) ? cnt : current;
                rstrm->in_finger += current;
                cnt -= current;
        }
        return (TRUE);
}

static u_int
fix_buf_size(
        u_int s)
{

        if (s < 100)
                s = 4000;
        return (RNDUP(s));
}