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/* authen_s.c - Send authentication request to the 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "libtac.h"
#include "xalloc.h"
#if defined(HAVE_OPENSSL_MD5_H) && defined(HAVE_LIBCRYPTO)
# include <openssl/md5.h>
#else
# include "md5.h"
#endif
/* assume digest points to a buffer MD5_LEN size */
static void
digest_chap(u_char digest[MD5_LBLOCK], uint8_t id,
const char *pass, unsigned pass_len,
const char *chal, unsigned chal_len) {
MD5_CTX mdcontext;
MD5_Init(&mdcontext);
/* multiple calls to MD5Update() is still much less overhead
* than allocating a buffer and marshalling contiguous data
* for a single call.
*/
MD5_Update(&mdcontext, &id, sizeof(id));
MD5_Update(&mdcontext, (const u_char *)pass, pass_len);
MD5_Update(&mdcontext, (const u_char *)chal, chal_len);
MD5_Final(digest, &mdcontext);
}
/* this function sends a packet do TACACS+ server, asking
* for validation of given username and password
*
* return value:
* 0 : success
* < 0 : error status code, see LIBTAC_STATUS_...
* LIBTAC_STATUS_WRITE_ERR
* LIBTAC_STATUS_WRITE_TIMEOUT
* LIBTAC_STATUS_ASSEMBLY_ERR
*/
int tac_authen_send(int fd, const char *user, const char *pass, const char *tty,
const char *r_addr, u_char action) {
HDR *th; /* TACACS+ packet header */
struct authen_start tb; /* message body */
int user_len, pass_len, port_len, chal_len, token_len, bodylength, w;
int r_addr_len;
int pkt_len = 0;
int ret = 0;
char *chal = "1234123412341234";
char *token = NULL;
u_char *pkt = NULL;
const uint8_t id = 5;
th = _tac_req_header(TAC_PLUS_AUTHEN, 0);
/* set some header options */
if (!strcmp(tac_login, "login")) {
th->version = TAC_PLUS_VER_0;
} else {
th->version = TAC_PLUS_VER_1;
}
th->encryption =
tac_encryption ?
TAC_PLUS_ENCRYPTED_FLAG : TAC_PLUS_UNENCRYPTED_FLAG;
TACDEBUG(LOG_DEBUG, "%s: user '%s', tty '%s', rem_addr '%s', encrypt: %s",
__FUNCTION__, user, tty, r_addr,
(tac_encryption) ? "yes" : "no");
/* get size of submitted data */
user_len = strlen(user);
chal_len = strlen(chal);
pass_len = strlen(pass);
port_len = strlen(tty);
r_addr_len = strlen(r_addr);
if (!strcmp(tac_login, "chap")) {
u_char digest[MD5_LBLOCK];
digest_chap(digest, id, pass, pass_len, chal, chal_len);
token_len = sizeof(id) + chal_len + sizeof(digest);
token = xcalloc(1, token_len);
token[0] = id;
memcpy(token + sizeof(id), chal, chal_len);
memcpy(token + sizeof(id) + chal_len, digest, sizeof(digest));
} else {
token = xstrdup(pass);
token_len = strlen(token);
}
/* fill the body of message */
tb.action = action;
tb.priv_lvl = tac_priv_lvl;
if (!*tac_login) {
/* default to PAP */
tb.authen_type =
TAC_PLUS_AUTHEN_CHPASS == action ?
TAC_PLUS_AUTHEN_TYPE_ASCII : TAC_PLUS_AUTHEN_TYPE_PAP;
} else {
if (!strcmp(tac_login, "chap")) {
tb.authen_type = TAC_PLUS_AUTHEN_TYPE_CHAP;
} else if (!strcmp(tac_login, "login")) {
tb.authen_type = TAC_PLUS_AUTHEN_TYPE_ASCII;
} else {
tb.authen_type = TAC_PLUS_AUTHEN_TYPE_PAP;
}
}
/* data field is not used in ASCII login */
if (tb.authen_type == TAC_PLUS_AUTHEN_TYPE_ASCII) {
token_len = 0;
}
tb.service = tac_authen_service;
tb.user_len = user_len;
tb.port_len = port_len;
tb.r_addr_len = r_addr_len; /* may be e.g Caller-ID in future */
tb.data_len = token_len;
/* fill body length in header */
bodylength = sizeof(tb) + user_len + port_len + r_addr_len + token_len;
th->datalength = htonl(bodylength);
/* we can now write the header */
w = write(fd, th, TAC_PLUS_HDR_SIZE);
if (w < 0 || w < TAC_PLUS_HDR_SIZE) {
TACSYSLOG(
LOG_ERR, "%s: short write on header, wrote %d of %d: %m", __FUNCTION__, w, TAC_PLUS_HDR_SIZE);
free(token);
free(pkt);
free(th);
return LIBTAC_STATUS_WRITE_ERR;
}
/* build the packet */
pkt = (u_char *) xcalloc(1, bodylength + 10);
bcopy(&tb, pkt + pkt_len, sizeof(tb)); /* packet body beginning */
pkt_len += sizeof(tb);
bcopy(user, pkt + pkt_len, user_len); /* user */
pkt_len += user_len;
bcopy(tty, pkt + pkt_len, port_len); /* tty */
pkt_len += port_len;
bcopy(r_addr, pkt + pkt_len, r_addr_len); /* rem addr */
pkt_len += r_addr_len;
bcopy(token, pkt + pkt_len, token_len); /* password */
pkt_len += token_len;
/* pkt_len == bodylength ? */
if (pkt_len != bodylength) {
TACSYSLOG(
LOG_ERR, "%s: bodylength %d != pkt_len %d", __FUNCTION__, bodylength, pkt_len);
free(token);
free(pkt);
free(th);
return LIBTAC_STATUS_ASSEMBLY_ERR;
}
/* encrypt the body */
_tac_crypt(pkt, th);
w = write(fd, pkt, pkt_len);
if (w < 0 || w < pkt_len) {
TACSYSLOG(
LOG_ERR, "%s: short write on body, wrote %d of %d: %m", __FUNCTION__, w, pkt_len);
ret = LIBTAC_STATUS_WRITE_ERR;
}
free(token);
free(pkt);
free(th);
TACDEBUG(LOG_DEBUG, "%s: exit status=%d", __FUNCTION__, ret);
return ret;
} /* tac_authen_send */
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