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auth2-chall.c
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auth2-chall.c
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/*
* Copyright (c) 2001 Markus Friedl. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 "includes.h"
RCSID("$OpenBSD: auth2-chall.c,v 1.4 2001/03/28 22:43:31 markus Exp $");
#include "ssh2.h"
#include "auth.h"
#include "packet.h"
#include "xmalloc.h"
#include "dispatch.h"
#include "log.h"
void send_userauth_into_request(Authctxt *authctxt, char *challenge, int echo);
void input_userauth_info_response(int type, int plen, void *ctxt);
/*
* try challenge-reponse, return -1 (= postponed) if we have to
* wait for the response.
*/
int
auth2_challenge(Authctxt *authctxt, char *devs)
{
char *challenge;
if (!authctxt->valid || authctxt->user == NULL)
return 0;
if ((challenge = get_challenge(authctxt, devs)) == NULL)
return 0;
send_userauth_into_request(authctxt, challenge, 0);
dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,
&input_userauth_info_response);
authctxt->postponed = 1;
return 0;
}
void
send_userauth_into_request(Authctxt *authctxt, char *challenge, int echo)
{
int nprompts = 1;
packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
/* name, instruction and language are unused */
packet_put_cstring("");
packet_put_cstring("");
packet_put_cstring("");
packet_put_int(nprompts);
packet_put_cstring(challenge);
packet_put_char(echo);
packet_send();
packet_write_wait();
}
void
input_userauth_info_response(int type, int plen, void *ctxt)
{
Authctxt *authctxt = ctxt;
int authenticated = 0;
u_int nresp, rlen;
char *response, *method = "challenge-reponse";
if (authctxt == NULL)
fatal("input_userauth_info_response: no authctxt");
authctxt->postponed = 0; /* reset */
nresp = packet_get_int();
if (nresp == 1) {
response = packet_get_string(&rlen);
packet_done();
if (strlen(response) == 0) {
/*
* if we received an empty response, resend challenge
* with echo enabled
*/
char *challenge = get_challenge(authctxt, NULL);
if (challenge != NULL) {
send_userauth_into_request(authctxt,
challenge, 1);
authctxt->postponed = 1;
}
} else if (authctxt->valid) {
authenticated = verify_response(authctxt, response);
memset(response, 'r', rlen);
}
xfree(response);
}
/* unregister callback */
if (!authctxt->postponed)
dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
userauth_finish(authctxt, authenticated, method);
}

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