/* rpcCksum.c - xdr checksum filter for UDP trame *//* Copyright 1995-1998 Wind River Systems, Inc. */#include "copyright_wrs.h"/*modification history--------------------01d,22jan98,c_c  Removed EXT_FUNC references.01c,15jan96,elp added windll.h to see external function macros		WIN32 DLL external functions are called through pointers.01b,21jun95,tpr changed code inside xdrCksum().01a,12jun95,tpr	created.*//*DESCRIPTIONThis XDR filter either computes the XDR stream checksun and put thisvalue inside the stream or checks that the xdr stream checksum match thechecksum inside the stream.*//* includes */#include <rpc/rpc.h>#include "wdbP.h"#ifdef HOST#include "wpwrutil.h"#endif	/* HOST *//* defines */#define WDB_CKSUM_FLAG	0xffff0000#define WDB_XDR_STREAM_MAX_SIZE	0x1000/* statics */LOCAL BOOL	xdr_wdb_cksum_enabled = TRUE;/******************************************************************************** xdrCksum - returns the ones compliment checksum of some memory.** NOMANUAL*/UINT32 xdrCksum    (    unsigned short *	pAddr,			/* start of buffer */    int			len			/* size of buffer in bytes */    )    {    UINT32	sum = 0;    BOOL	swap = FALSE;    /* take care of unaligned buffer address */    if ((UINT32)pAddr & 0x1)	{	sum += *((unsigned char *) pAddr);	pAddr = (unsigned short *)(((unsigned char *)pAddr) + 1);	len--;	swap = TRUE;	}    /* evaluate checksum */    while (len > 1)	{	sum += * (pAddr ++);	len -= 2;	}    /* take care of last byte */    if (len > 0)	sum = sum + ((*(unsigned char *) pAddr) << 8);    /* fold to 16 bits */    sum = (sum & 0xffff) + (sum >> 16);    sum = (sum & 0xffff) + (sum >> 16);    /* swap if we started on unaligned address */    if (swap)	sum = ((sum & 0x00ff) << 8) | ((sum & 0xff00) >> 8);    return (~sum);    }/********************************************************************************* xdr_CHECKSUM - checksum an XDR stream** When data are encoded in the XDR stream, this function computes the* checksum of the XDR stream pointer to by <xdr>. The checksum is performed* between the start point of the XDR stream and the current position in the* stream. The XDR stream size and checksum value are placed in the stream* at the <xdrStreamSizePos> and <xdrCksumValPos> position.** When data are decoded from the stream, the filter verifies that the stream* checksum value match the checkum value inside the stream. One of the checksum* feature is when the checksum value of a buffer is included inside this buffer,* its checksum value is equal to zero. This feature is used by this function* to check if checksum values are equal.** RETURN: TRUE no error was detected otherwise FALSE.*/BOOL xdr_CHECKSUM    (    XDR *	xdrs,			/* xdr to compute/check the checksum */    UINT32	xdrCksumVal,		/* xdr stream checksum value */    UINT32	xdrStreamSize,		/* xdr stream size */    UINT32	xdrCksumValPos,		/* checksum value inside the steam */    UINT32	xdrStreamSizePos	/* stream size inside the xdr steam */    )    {    long *		xdrStreamAddr;	/* xdr stream buffer address */    u_int		xdrStreamPos;	/* xdr strean current position */    u_int		cksum = 0x00;  	/* checksum() return value */    switch (xdrs->x_op)	{	case XDR_ENCODE:	    /* return if the xdr stream checksum capability is not enabled */	    if (!xdr_wdb_cksum_enabled)		return (TRUE);	    /* save the current position in the xdr stream */	    xdrStreamPos = XDR_GETPOS (xdrs);	    /* get the xdr stream address */	    if ((xdrStreamAddr = xdr_inline (xdrs, 0)) == NULL)		return (FALSE);	    /* compute the xdr stream start address */	    xdrStreamAddr = (long *) ((char *) xdrStreamAddr - xdrStreamPos +	    					sizeof (UINT32));	    /* set the current position at the xdr stream size value */	    if (!XDR_SETPOS (xdrs, xdrStreamSizePos))		return (FALSE);	    /* compute the XDR stream size */	    xdrStreamSize = xdrStreamPos - sizeof (UINT32);	    /* save the xdr stream size into the xdr stream */	    if (!xdr_UINT32 (xdrs, &xdrStreamSize))		return (FALSE);	    /* checksum the xdr stream */	    cksum = (u_int) xdrCksum ((unsigned short *) xdrStreamAddr,								xdrStreamSize);	    cksum = htons (cksum);	    /* set the flag to signal the xdr stream checksum is available */	    cksum |= WDB_CKSUM_FLAG;	    /* set the current position at the xdr stream checksum value */	    if (!XDR_SETPOS (xdrs, xdrCksumValPos))		return (FALSE);	    /* put the xdr stream checksum value in the xdr steam */	    if (!xdr_UINT32 (xdrs, &cksum))		return (FALSE);	    /* restore the current position in the xdr stream */	    if (!XDR_SETPOS (xdrs, xdrStreamPos))		return (FALSE);            break;	case XDR_DECODE:	    if (!xdr_wdb_cksum_enabled) 		{	        /* 	         * if the xdr stream checksum capability is desabled and the	         * checksum is performed on the reveiced stream then turn on	         * the checksum capability and control checkum coherency.	         */		if (xdrCksumVal & WDB_CKSUM_FLAG)		    xdr_wdb_cksum_enabled = TRUE;		else 		    return (TRUE);		}	    else 		if (!(xdrCksumVal & WDB_CKSUM_FLAG))		    {		    /*		     * Turn off checksum capability because the reveiced		     * stream is sent without its checksum.		     */#ifdef	HOST		    wpwrLogWarn ("The agent doesn't provide XDR stream checksum\n");#endif		    xdr_wdb_cksum_enabled = FALSE;		    return (TRUE);		    }	    /* save the current position in the xdr stream */	    xdrStreamPos = XDR_GETPOS (xdrs);	    /* get the xdr stream address */	    if ((xdrStreamAddr = xdr_inline (xdrs, 0)) == NULL)		return (FALSE);	    /* compute the xdr stream start address */	    xdrStreamAddr = (long *) ((char *) xdrStreamAddr - xdrStreamPos +						sizeof (UINT32));	    /*	     * check the xdr stream size is not too big. The size	     * field may be corrupted.	     */	    if (WDB_XDR_STREAM_MAX_SIZE < xdrStreamSize)		return (FALSE);	    /* checksum the xdr stream */	    cksum = (u_int) xdrCksum ((unsigned short *) xdrStreamAddr,								xdrStreamSize);	    /* 	     * if the received stream is not corrupted its checksun value 	     * should be equal to zero because its checksum value is inside	     * the stream.	     * if checksum is different from 0 then the received stream is 	     * corrupted. So return FLASE .	     */	    if ((cksum & ~WDB_CKSUM_FLAG) != 0)		return (FALSE);            break;	default:	    break;	}     return (TRUE);     }