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/* authen_r.c - Read authentication reply from server.
*
* Copyright (C) 2010, Pawel Krawczyk <pawel.krawczyk@hush.com> and
* Jeroen Nijhof <jeroen@jeroennijhof.nl>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program - see the file COPYING.
*
* See `CHANGES' file for revision history.
*/
#include "xalloc.h"
#include "libtac.h"
#include "messages.h"
/* reads packet from TACACS+ server; returns:
* TAC_PLUS_AUTHEN_STATUS_PASS if the authentication succeded
* an other integer if failed. Check tacplus.h for all possible values
*
* return value:
* < 0 : error status code, see LIBTAC_STATUS_...
* LIBTAC_STATUS_READ_TIMEOUT
* LIBTAC_STATUS_SHORT_HDR
* LIBTAC_STATUS_SHORT_BODY
* LIBTAC_STATUS_PROTOCOL_ERR
* >= 0 : server response, see TAC_PLUS_AUTHEN_STATUS_...
*/
int tac_authen_read(int fd, struct areply *re) {
HDR th;
struct authen_reply *tb = NULL;
size_t len_from_header, len_from_body;
ssize_t spacket_read;
char *msg = NULL;
int timeleft = 0;
memset(re, 0, sizeof(struct areply));
/* read the reply header */
if (tac_readtimeout_enable
&& tac_read_wait(fd, tac_timeout * 1000, TAC_PLUS_HDR_SIZE,
&timeleft) < 0) {
TACSYSLOG(
LOG_ERR, "%s: reply timeout after %u secs", __FUNCTION__, tac_timeout);
re->status = LIBTAC_STATUS_READ_TIMEOUT;
free(tb);
return re->status;
}
spacket_read = read(fd, &th, TAC_PLUS_HDR_SIZE);
if (spacket_read < TAC_PLUS_HDR_SIZE) {
TACSYSLOG(
LOG_ERR, "%s: short reply header, read %zd of %d: %m", __FUNCTION__, spacket_read, TAC_PLUS_HDR_SIZE);
re->status = LIBTAC_STATUS_SHORT_HDR;
free(tb);
return re->status;
}
/* check the reply fields in header */
msg = _tac_check_header(&th, TAC_PLUS_AUTHEN);
if (msg != NULL) {
re->msg = xstrdup(msg);
re->status = LIBTAC_STATUS_PROTOCOL_ERR;
free(tb);
return re->status;
}
re->seq_no = th.seq_no;
len_from_header = ntohl(th.datalength);
if (len_from_header > TAC_PLUS_MAX_PACKET_SIZE) {
TACSYSLOG(
LOG_ERR, "%s: length declared in the packet %zu exceeds max packet size %d", __FUNCTION__, len_from_header, TAC_PLUS_MAX_PACKET_SIZE);
re->status = LIBTAC_STATUS_PROTOCOL_ERR;
free(tb);
return re->status;
}
tb = (struct authen_reply *) xcalloc(1, len_from_header);
/* read reply packet body */
if (tac_readtimeout_enable
&& tac_read_wait(fd, timeleft, len_from_header, NULL) < 0) {
TACSYSLOG(
LOG_ERR, "%s: reply timeout after %u secs", __FUNCTION__, tac_timeout);
re->msg = xstrdup(authen_syserr_msg);
re->status = LIBTAC_STATUS_READ_TIMEOUT;
free(tb);
return re->status;
}
spacket_read = read(fd, tb, len_from_header);
if (spacket_read < (ssize_t) len_from_header) {
TACSYSLOG(
LOG_ERR, "%s: short reply body, read %zd of %zu: %m", __FUNCTION__, spacket_read, len_from_header);
re->msg = xstrdup(authen_syserr_msg);
re->status = LIBTAC_STATUS_SHORT_BODY;
free(tb);
return re->status;
}
/* decrypt the body */
_tac_crypt((u_char *) tb, &th);
/* Convert network byte order to host byte order */
tb->msg_len = ntohs(tb->msg_len);
tb->data_len = ntohs(tb->data_len);
/* check the length fields */
len_from_body = sizeof(tb->status) + sizeof(tb->flags) + sizeof(tb->msg_len)
+ sizeof(tb->data_len) + tb->msg_len + tb->data_len;
if (len_from_header != len_from_body) {
TACSYSLOG(
LOG_ERR, "%s: inconsistent reply body, incorrect key?", __FUNCTION__);
re->msg = xstrdup(protocol_err_msg);
re->status = LIBTAC_STATUS_PROTOCOL_ERR;
free(tb);
return re->status;
}
/* save status and clean up */
re->status = tb->status;
if (0 < tb->msg_len) {
msg = xcalloc(tb->msg_len + 1, sizeof(char));
memset(msg, 0, (tb->msg_len + 1));
memcpy(msg, (char*) tb + sizeof(struct authen_reply), tb->msg_len);
re->msg = msg;
}
/* server authenticated username and password successfully */
if (re->status == TAC_PLUS_AUTHEN_STATUS_PASS) {
TACDEBUG(LOG_DEBUG, "%s: authentication ok", __FUNCTION__);
free(tb);
return re->status;
}
/* server ask for continue packet with password */
if (re->status == TAC_PLUS_AUTHEN_STATUS_GETPASS) {
TACDEBUG(LOG_DEBUG, "%s: continue packet with password needed", __FUNCTION__);
free(tb);
return re->status;
}
/* server wants to prompt user for more data */
if (re->status == TAC_PLUS_AUTHEN_STATUS_GETDATA) {
re->flags = tb->flags;
TACDEBUG(LOG_DEBUG, "%s: continue packet with data request: msg=%.*s",
__func__, tb->msg_len, (char*)tb + sizeof(struct authen_reply));
free(tb);
return re->status;
}
TACDEBUG(LOG_DEBUG, "%s: authentication failed, server reply status=%d",
__FUNCTION__, re->status);
free(tb);
return re->status;
} /* tac_authen_read */
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