/*
 * lib/gssapi/krb5/set_allowable_enctypes.c
 *
 * Copyright 2004  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.
 *
 * krb5_gss_set_allowable_enctypes()
 */

/*
 * gss_krb5_set_allowable_enctypes
 *
 * This function may be called by a context initiator after calling
 * gss_acquire_cred(), but before calling gss_init_sec_context(),
 * to restrict the set of enctypes which will be negotiated during
 * context establishment to those in the provided array.
 *
 * 'cred_handle' must be a valid credential handle obtained via
 * gss_acquire_cred().  It may not be GSS_C_NO_CREDENTIAL.
 * gss_acquire_cred() may be called with GSS_C_NO_CREDENTIAL
 * to get a handle to the default credential.
 *
 * The purpose of this function is to limit the keys that may
 * be exported via gss_krb5_export_lucid_sec_context(); thus it
 * should limit the enctypes of all keys that will be needed
 * after the security context has been established.
 * (i.e. context establishment may use a session key with a
 * stronger enctype than in the provided array, however a
 * subkey must be established within the enctype limits
 * established by this function.)
 *
 */

#include "gssapiP_krb5.h"
#ifdef HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#include "gssapi_krb5.h"

OM_uint32 KRB5_CALLCONV
gss_krb5int_set_allowable_enctypes(OM_uint32 *minor_status, 
				   gss_cred_id_t cred_handle,
				   OM_uint32 num_ktypes,
				   krb5_enctype *ktypes)
{
    int i;
    krb5_enctype * new_ktypes;
    OM_uint32 major_status;
    krb5_gss_cred_id_t cred;
    krb5_error_code kerr = 0;
    OM_uint32 temp_status;

    /* Assume a failure */
    *minor_status = 0;
    major_status = GSS_S_FAILURE;

    /* verify and valildate cred handle */
    if (cred_handle == GSS_C_NO_CREDENTIAL) {
	kerr = KRB5_NOCREDS_SUPPLIED;
	goto error_out;
    }
    major_status = krb5_gss_validate_cred(&temp_status, cred_handle);
    if (GSS_ERROR(major_status)) {
	kerr = temp_status;
	goto error_out;
    }
    cred = (krb5_gss_cred_id_t) cred_handle;

    if (ktypes) {
	for (i = 0; i < num_ktypes && ktypes[i]; i++) {
	    if (!krb5_c_valid_enctype(ktypes[i])) {
		kerr = KRB5_PROG_ETYPE_NOSUPP;
		goto error_out;
	    }
	}
    } else {
	kerr = k5_mutex_lock(&cred->lock);
	if (kerr)
	    goto error_out;
	if (cred->req_enctypes)
	    free(cred->req_enctypes);
	cred->req_enctypes = NULL;
	k5_mutex_unlock(&cred->lock);
	return GSS_S_COMPLETE;
    }

    /* Copy the requested ktypes into the cred structure */
    if ((new_ktypes = (krb5_enctype *)malloc(sizeof(krb5_enctype) * (i + 1)))) {
	memcpy(new_ktypes, ktypes, sizeof(krb5_enctype) * i);
	new_ktypes[i] = 0;	/* "null-terminate" the list */
    }
    else {
	kerr = ENOMEM;
	goto error_out;
    }
    kerr = k5_mutex_lock(&cred->lock);
    if (kerr) {
	free(new_ktypes);
	goto error_out;
    }
    if (cred->req_enctypes)
	free(cred->req_enctypes);
    cred->req_enctypes = new_ktypes;
    k5_mutex_unlock(&cred->lock);

    /* Success! */
    return GSS_S_COMPLETE;

error_out:
    *minor_status = kerr;
    return(major_status);
}
