mk_rep.c

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/*
 * Copyright (c) 1997 - 2003 Kungliga Tekniska H鰃skolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 *
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 */

#include <krb5_locl.h>

RCSID("$Id: mk_rep.c 13863 2004-05-25 21:46:46Z lha $");

krb5_error_code KRB5_LIB_FUNCTION
krb5_mk_rep(krb5_context context,
	    krb5_auth_context auth_context,
	    krb5_data *outbuf)
{
    krb5_error_code ret;
    AP_REP ap;
    EncAPRepPart body;
    u_char *buf = NULL;
    size_t buf_size;
    size_t len;
    krb5_crypto crypto;

    ap.pvno = 5;
    ap.msg_type = krb_ap_rep;

    memset (&body, 0, sizeof(body));

    body.ctime = auth_context->authenticator->ctime;
    body.cusec = auth_context->authenticator->cusec;
    if (auth_context->flags & KRB5_AUTH_CONTEXT_USE_SUBKEY) {
	if (auth_context->local_subkey == NULL) {
	    ret = krb5_auth_con_generatelocalsubkey(context,
						    auth_context,
						    auth_context->keyblock);
	    if(ret) {
		krb5_set_error_string (context,
				       "krb5_mk_rep: generating subkey");
		free_EncAPRepPart(&body);
		return ret;
	    }
	}
	ret = krb5_copy_keyblock(context, auth_context->local_subkey,
				 &body.subkey);
	if (ret) {
	    krb5_set_error_string (context,
				   "krb5_copy_keyblock: out of memory");
	    free_EncAPRepPart(&body);
	    return ENOMEM;
	}
    } else
	body.subkey = NULL;
    if (auth_context->flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE) {
	if(auth_context->local_seqnumber == 0) 
	    krb5_generate_seq_number (context,
				      auth_context->keyblock,
				      &auth_context->local_seqnumber);
	ALLOC(body.seq_number, 1);
	if (body.seq_number == NULL) {
	    krb5_set_error_string (context, "malloc: out of memory");
	    free_EncAPRepPart(&body);
	    return ENOMEM;
	}
	*(body.seq_number) = auth_context->local_seqnumber;
    } else
	body.seq_number = NULL;

    ap.enc_part.etype = auth_context->keyblock->keytype;
    ap.enc_part.kvno  = NULL;

    ASN1_MALLOC_ENCODE(EncAPRepPart, buf, buf_size, &body, &len, ret);
    free_EncAPRepPart (&body);
    if(ret)
	return ret;
    if (buf_size != len)
	krb5_abortx(context, "internal error in ASN.1 encoder");
    ret = krb5_crypto_init(context, auth_context->keyblock, 
			   0 /* ap.enc_part.etype */, &crypto);
    if (ret) {
	free (buf);
	return ret;
    }
    ret = krb5_encrypt (context,
			crypto,
			KRB5_KU_AP_REQ_ENC_PART,
			buf + buf_size - len, 
			len,
			&ap.enc_part.cipher);
    krb5_crypto_destroy(context, crypto);
    free(buf);
    if (ret)
	return ret;

    ASN1_MALLOC_ENCODE(AP_REP, outbuf->data, outbuf->length, &ap, &len, ret);
    if (ret == 0 && outbuf->length != len)
	krb5_abortx(context, "internal error in ASN.1 encoder");
    free_AP_REP (&ap);
    return ret;
}