/*
 * Copyright (c) 1997 - 2006 Kungliga Tekniska Högskolan
 * (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"

/*
 * The format seems to be:
 * client -> server
 *
 * 4 bytes - length
 * KRB5_SENDAUTH_V1.0 (including zero)
 * 4 bytes - length
 * protocol string (with terminating zero)
 *
 * server -> client
 * 1 byte - (0 = OK, else some kind of error)
 *
 * client -> server
 * 4 bytes - length
 * AP-REQ
 *
 * server -> client
 * 4 bytes - length (0 = OK, else length of error)
 * (error)
 *
 * if(mutual) {
 * server -> client
 * 4 bytes - length
 * AP-REP
 * }
 */

/**
 * Perform the client side of the sendauth protocol.
 *
 * @param context        Kerberos 5 context.
 * @param auth_context   Authentication context of the peer.
 * @param p_fd           Socket associated to the connection.
 * @param appl_version   Server-specific string.
 * @param client         Client principal. If NULL, use the credentials in \a ccache.
 * @param server         Server principal.
 * @param ap_req_options Options for the AP_REQ message. See the AP_OPTS_* defines in krb5.h.
 * @param in_data        FIXME
 * @param in_creds       FIXME
 * @param ccache         Credentials cache. If NULL, use the default credentials cache.
 * @param ret_error      If not NULL, will be set to the error reported by server, if any.
 *                       Must be deallocated with krb5_free_error_contents().
 * @param rep_result     If not NULL, will be set to the EncApRepPart of the AP_REP message.
 *                       Must be deallocated with krb5_free_ap_rep_enc_part().
 * @param out_creds      FIXME If not NULL, will be set to FIXME. Must be deallocated with
 *                       krb5_free_creds().
 *
 * @return 0 to indicate success. Otherwise a Kerberos error code is
 *         returned, see krb5_get_error_message().
 */
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_sendauth(krb5_context context,
	      krb5_auth_context *auth_context,
	      krb5_pointer p_fd,
	      const char *appl_version,
	      krb5_principal client,
	      krb5_principal server,
	      krb5_flags ap_req_options,
	      krb5_data *in_data,
	      krb5_creds *in_creds,
	      krb5_ccache ccache,
	      krb5_error **ret_error,
	      krb5_ap_rep_enc_part **rep_result,
	      krb5_creds **out_creds)
{
    krb5_error_code ret;
    uint32_t len, net_len;
    const char *version = KRB5_SENDAUTH_VERSION;
    u_char repl;
    krb5_data ap_req, error_data;
    krb5_creds this_cred;
    krb5_principal this_client = NULL;
    krb5_creds *creds;
    ssize_t sret;
    krb5_boolean my_ccache = FALSE;

    len = strlen(version) + 1;
    net_len = htonl(len);
    if (krb5_net_write (context, p_fd, &net_len, 4) != 4
	|| krb5_net_write (context, p_fd, version, len) != len) {
	ret = errno;
	krb5_set_error_message (context, ret, "write: %s", strerror(ret));
	return ret;
    }

    len = strlen(appl_version) + 1;
    net_len = htonl(len);
    if (krb5_net_write (context, p_fd, &net_len, 4) != 4
	|| krb5_net_write (context, p_fd, appl_version, len) != len) {
	ret = errno;
	krb5_set_error_message (context, ret, "write: %s", strerror(ret));
	return ret;
    }

    sret = krb5_net_read (context, p_fd, &repl, sizeof(repl));
    if (sret < 0) {
	ret = errno;
	krb5_set_error_message (context, ret, "read: %s", strerror(ret));
	return ret;
    } else if (sret != sizeof(repl)) {
	krb5_clear_error_message (context);
	return KRB5_SENDAUTH_BADRESPONSE;
    }

    if (repl != 0) {
	krb5_clear_error_message (context);
	return KRB5_SENDAUTH_REJECTED;
    }

    if (in_creds == NULL) {
	if (ccache == NULL) {
	    ret = krb5_cc_default (context, &ccache);
	    if (ret)
		return ret;
	    my_ccache = TRUE;
	}

	if (client == NULL) {
	    ret = krb5_cc_get_principal (context, ccache, &this_client);
	    if (ret) {
		if(my_ccache)
		    krb5_cc_close(context, ccache);
		return ret;
	    }
	    client = this_client;
	}
	memset(&this_cred, 0, sizeof(this_cred));
	this_cred.client = client;
	this_cred.server = server;
	this_cred.times.endtime = 0;
	this_cred.ticket.length = 0;
	in_creds = &this_cred;
    }
    if (in_creds->ticket.length == 0) {
	ret = krb5_get_credentials (context, 0, ccache, in_creds, &creds);
	if (ret) {
	    if(my_ccache)
		krb5_cc_close(context, ccache);
	    return ret;
	}
    } else {
	creds = in_creds;
    }
    if(my_ccache)
	krb5_cc_close(context, ccache);
    ret = krb5_mk_req_extended (context,
				auth_context,
				ap_req_options,
				in_data,
				creds,
				&ap_req);

    if (out_creds)
	*out_creds = creds;
    else
	krb5_free_creds(context, creds);
    if(this_client)
	krb5_free_principal(context, this_client);

    if (ret)
	return ret;

    ret = krb5_write_message (context,
			      p_fd,
			      &ap_req);
    if (ret)
	return ret;

    krb5_data_free (&ap_req);

    ret = krb5_read_message (context, p_fd, &error_data);
    if (ret)
	return ret;

    if (error_data.length != 0) {
	KRB_ERROR error;

	ret = krb5_rd_error (context, &error_data, &error);
	krb5_data_free (&error_data);
	if (ret == 0) {
	    ret = krb5_error_from_rd_error(context, &error, NULL);
	    if (ret_error != NULL) {
		*ret_error = malloc (sizeof(krb5_error));
		if (*ret_error == NULL) {
		    krb5_free_error_contents (context, &error);
		} else {
		    **ret_error = error;
		}
	    } else {
		krb5_free_error_contents (context, &error);
	    }
	    return ret;
	} else {
	    krb5_clear_error_message(context);
	    return ret;
	}
    } else
	krb5_data_free (&error_data);

    if (ap_req_options & AP_OPTS_MUTUAL_REQUIRED) {
	krb5_data ap_rep;
	krb5_ap_rep_enc_part *ignore = NULL;

	krb5_data_zero (&ap_rep);
	ret = krb5_read_message (context,
				 p_fd,
				 &ap_rep);
	if (ret)
	    return ret;

	ret = krb5_rd_rep (context, *auth_context, &ap_rep,
			   rep_result ? rep_result : &ignore);
	krb5_data_free (&ap_rep);
	if (ret)
	    return ret;
	if (rep_result == NULL)
	    krb5_free_ap_rep_enc_part (context, ignore);
    }
    return 0;
}