/*
 * functions to encode/decode Kerberos V5 principals
 * into something that can be reasonable spewed over
 * the wire
 *
 * Author: Tom Yu <tlyu@MIT.EDU>
 *
 * Still needs to be fixed up wrt signed/unsigned lengths, but we'll worry
 * about that later.
 */

#include <krb5/krb5.h>
#include <X11/X.h>
#include <X11/Xos.h>
#include <X11/Xmd.h>
#include <X11/Xfuncs.h>
#include <X11/k5encode.h>

/*
 * k5_encode
 *
 * this function encodes the principal passed to it in a format that can
 * easily be dealt with by stuffing it into an X packet.  Encoding is as
 * follows:
 *   length count of the realm name
 *   realm
 *   component count
 *   length of component
 *   actual principal component
 *   etc....
 *
 * Note that this function allocates a hunk of memory, which must be
 * freed to avoid nasty memory leak type things.  All counts are
 * byte-swapped if needed. (except for the total length returned)
 *
 * nevermind.... stuffing the encoded packet in net byte order just to
 * always do the right thing.  Don't have to frob with alignment that way.
 */
k5_encode(princ, outbuf)
    krb5_principal princ;	/* principal to encode */
    krb5_data *outbuf;		/* output buffer */
{
    CARD16 i, numparts, totlen = 0, plen, rlen;
    char *cp, *pdata;

    rlen = krb5_princ_realm(princ)->length;
    numparts = krb5_princ_size(princ);
    totlen = 2 + rlen + 2;	/* include room for realm length
				   and component count */
    for (i = 0; i < numparts; i++)
	totlen += krb5_princ_component(princ, i)->length + 2;
    /* add 2 bytes each time for length */
    if ((outbuf->data = (char *)malloc(totlen)) == NULL)
	return -1;
    cp = outbuf->data;
    *cp++ = (char)((0xff00 & rlen) >> 8);
    *cp++ = (char)(0x00ff & rlen);
    bcopy(krb5_princ_realm(princ)->data, cp, rlen);
    cp += rlen;
    *cp++ = (char)((0xff00 & numparts) >> 8);
    *cp++ = (char)(0x00ff & numparts);
    for (i = 0; i < numparts; i++)
    {
	plen = krb5_princ_component(princ, i)->length;
	pdata = krb5_princ_component(princ, i)->data;
	*cp++ = (char)((0xff00 & plen) >> 8);
	*cp++ = (char)(0x00ff & plen);
	bcopy(pdata, cp, plen);
	cp += plen;
    }
    outbuf->length = totlen;
    return 0;
}

/*
 * k5_decode
 *
 * this function essentially reverses what k5_encode does
 */
k5_decode(inbuf, princ)
    krb5_data inbuf;
    krb5_principal *princ;
{
    CARD16 i, numparts, plen, rlen;
    CARD8 *cp, *pdata;
    
    if (inbuf.length < 4)
    {
	krb5_free_principal(*princ);
	return -1;
    }
    *princ = (krb5_principal)malloc(sizeof (krb5_principal_data));
    if (*princ == NULL)
	return -1;
    bzero(*princ, sizeof (krb5_principal_data));
    cp = (CARD8 *)inbuf.data;
    rlen = *cp++ << 8;
    rlen |= *cp++;
    if (inbuf.length < 4 + rlen + 2)
    {
	krb5_free_principal(*princ);
	return -1;
    }
    krb5_princ_realm(*princ)->data = (char *)malloc(rlen);
    if (krb5_princ_realm(*princ)->data == NULL)
    {
	krb5_free_principal(*princ);
	return -1;
    }
    krb5_princ_realm(*princ)->length = rlen;
    bcopy(cp, krb5_princ_realm(*princ)->data, rlen);
    cp += rlen;
    numparts = *cp++ << 8;
    numparts |= *cp++;
    krb5_princ_name(*princ) =
	(krb5_data *)malloc(numparts * sizeof (krb5_data));
    krb5_princ_size(*princ) = 0;
    for (i = 0; i < numparts; i++)
    {
	if (cp + 2 > (CARD8 *)inbuf.data + inbuf.length)
	{
	    krb5_free_principal(*princ);
	    return -1;
	}
	plen = *cp++ << 8;
	plen |= *cp++;
	if (cp + plen > (CARD8 *)inbuf.data + inbuf.length)
	{
	    krb5_free_principal(*princ);
	    return -1;
	}
	pdata = (CARD8 *)malloc(plen);
	if (pdata == NULL)
	{
	    krb5_free_principal(*princ);
	    return -1;
	}
	krb5_princ_component(*princ, i)->data = (char *)pdata;
	krb5_princ_component(*princ, i)->length = plen;
	bcopy(cp, pdata, plen);
	cp += plen;
	krb5_princ_size(*princ)++;
    }
    return 0;
}