ser_cksum.c   [plain text]

/*
 * lib/krb5/krb/ser_cksum.c
 *
 * Copyright 1995, 2008 by the Massachusetts Institute of Technology.
 * All Rights Reserved.
 *
 * Export of this software from the United States of America may
 *   require a specific license from the United States Government.
 *   It is the responsibility of any person or organization contemplating
 *   export to obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  Furthermore if you modify this software you must label
 * your software as modified software and not distribute it in such a
 * fashion that it might be confused with the original M.I.T. software.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 *
 */

/*
 * ser_cksum.c - Serialize a krb5_checksum structure.
 */
#include "k5-int.h"
#include "int-proto.h"

/*
 * Routines to deal with externalizing the krb5_checksum:
 *	krb5_checksum_esize();
 *	krb5_checksum_externalize();
 *	krb5_checksum_internalize();
 */
static krb5_error_code krb5_checksum_esize
	(krb5_context, krb5_pointer, size_t *);
static krb5_error_code krb5_checksum_externalize
	(krb5_context, krb5_pointer, krb5_octet **, size_t *);
static krb5_error_code krb5_checksum_internalize
	(krb5_context,krb5_pointer *, krb5_octet **, size_t *);

/* Local data */
static const krb5_ser_entry krb5_checksum_ser_entry = {
    KV5M_CHECKSUM,			/* Type			*/
    krb5_checksum_esize,		/* Sizer routine	*/
    krb5_checksum_externalize,		/* Externalize routine	*/
    krb5_checksum_internalize		/* Internalize routine	*/
};

/*
 * krb5_checksum_esize()	- Determine the size required to externalize
 *				  the krb5_checksum.
 */
static krb5_error_code
krb5_checksum_esize(krb5_context kcontext, krb5_pointer arg, size_t *sizep)
{
    krb5_error_code	kret;
    krb5_checksum	*checksum;

    /*
     * krb5_checksum requires:
     *	krb5_int32		for KV5M_CHECKSUM
     *	krb5_int32		for checksum_type
     *	krb5_int32		for length
     *	krb5_int32		for KV5M_CHECKSUM
     *	checksum->length	for contents
     */
    kret = EINVAL;
    if ((checksum = (krb5_checksum *) arg)) {
	*sizep += (sizeof(krb5_int32) +
		   sizeof(krb5_int32) +
		   sizeof(krb5_int32) +
		   sizeof(krb5_int32) +
		   (size_t) checksum->length);
	kret = 0;
    }
    return(kret);
}

/*
 * krb5_checksum_externalize()	- Externalize the krb5_checksum.
 */
static krb5_error_code
krb5_checksum_externalize(krb5_context kcontext, krb5_pointer arg, krb5_octet **buffer, size_t *lenremain)
{
    krb5_error_code	kret;
    krb5_checksum	*checksum;
    size_t		required;
    krb5_octet		*bp;
    size_t		remain;

    required = 0;
    bp = *buffer;
    remain = *lenremain;
    kret = EINVAL;
    if ((checksum = (krb5_checksum *) arg)) {
	kret = ENOMEM;
	if (!krb5_checksum_esize(kcontext, arg, &required) &&
	    (required <= remain)) {
	    /* Our identifier */
	    (void) krb5_ser_pack_int32(KV5M_CHECKSUM, &bp, &remain);
		
	    /* Our checksum_type */
	    (void) krb5_ser_pack_int32((krb5_int32) checksum->checksum_type,
				       &bp, &remain);

	    /* Our length */
	    (void) krb5_ser_pack_int32((krb5_int32) checksum->length,
				       &bp, &remain);

	    /* Our contents */
	    (void) krb5_ser_pack_bytes(checksum->contents,
				       (size_t) checksum->length,
				       &bp, &remain);

	    /* Finally, our trailer */
	    (void) krb5_ser_pack_int32(KV5M_CHECKSUM, &bp, &remain);

	    kret = 0;
	    *buffer = bp;
	    *lenremain = remain;
	}
    }
    return(kret);
}

/*
 * krb5_checksum_internalize()	- Internalize the krb5_checksum.
 */
static krb5_error_code
krb5_checksum_internalize(krb5_context kcontext, krb5_pointer *argp, krb5_octet **buffer, size_t *lenremain)
{
    krb5_error_code	kret;
    krb5_checksum	*checksum;
    krb5_int32		ibuf;
    krb5_octet		*bp;
    size_t		remain;

    bp = *buffer;
    remain = *lenremain;
    kret = EINVAL;
    /* Read our magic number */
    if (krb5_ser_unpack_int32(&ibuf, &bp, &remain))
	ibuf = 0;
    if (ibuf == KV5M_CHECKSUM) {
	kret = ENOMEM;

	/* Get a checksum */
	if ((remain >= (2*sizeof(krb5_int32))) &&
	    (checksum = (krb5_checksum *) calloc(1, sizeof(krb5_checksum)))) {
	    /* Get the checksum_type */
	    (void) krb5_ser_unpack_int32(&ibuf, &bp, &remain);
	    checksum->checksum_type = (krb5_cksumtype) ibuf;

	    /* Get the length */
	    (void) krb5_ser_unpack_int32(&ibuf, &bp, &remain);
	    checksum->length = (int) ibuf;

	    /* Get the string */
	    if (!ibuf ||
		((checksum->contents = (krb5_octet *)
		  malloc((size_t) (ibuf))) &&
		 !(kret = krb5_ser_unpack_bytes(checksum->contents,
						(size_t) ibuf,
						&bp, &remain)))) {

		/* Get the trailer */
		kret = krb5_ser_unpack_int32(&ibuf, &bp, &remain);
		if (!kret && (ibuf == KV5M_CHECKSUM)) {
		    checksum->magic = KV5M_CHECKSUM;
		    *buffer = bp;
		    *lenremain = remain;
		    *argp = (krb5_pointer) checksum;
		}
		else
		    kret = EINVAL;
	    }
	    if (kret) {
		if (checksum->contents)
		    free(checksum->contents);
		free(checksum);
	    }
	}
    }
    return(kret);
}

/*
 * Register the checksum serializer.
 */
krb5_error_code
krb5_ser_checksum_init(krb5_context kcontext)
{
    return(krb5_register_serializer(kcontext, &krb5_checksum_ser_entry));
}