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/*
* lib/krb4/mk_req.c
*
* Copyright 1986, 1987, 1988, 2000 by the Massachusetts Institute of
* Technology. All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* This routine constructs a Kerberos 'safe msg', i.e. authenticated
* using a private session key to seed a checksum. Msg is NOT
* encrypted.
*
* Returns either <0 ===> error, or resulting size of message
*
* Steve Miller Project Athena MIT/DEC
*/
#include <stdio.h>
#include <string.h>
#include "krb.h"
#include "des.h"
#include "prot.h"
#include "lsb_addr_cmp.h"
#include "port-sockets.h"
extern int krb_debug;
/*
* krb_mk_safe() constructs an AUTH_MSG_SAFE message. It takes some
* user data "in" of "length" bytes and creates a packet in "out"
* consisting of the user data, a timestamp, and the sender's network
* address, followed by a checksum computed on the above, using the
* given "key". The length of the resulting packet is returned.
*
* The "out" packet consists of:
*
* Size Variable Field
* ---- -------- -----
*
* 1 byte KRB_PROT_VERSION protocol version number
* 1 byte AUTH_MSG_SAFE | message type plus local
* HOST_BYTE_ORDER byte order in low bit
*
* ===================== begin checksum ================================
*
* 4 bytes length length of user data
* length in user data
* 1 byte msg_time_5ms timestamp milliseconds
* 4 bytes sender->sin.addr.s_addr sender's IP address
*
* 4 bytes msg_time_sec or timestamp seconds with
* -msg_time_sec direction in sign bit
*
* ======================= end checksum ================================
*
* 16 bytes big_cksum quadratic checksum of
* above using "key"
*/
long KRB5_CALLCONV
krb_mk_safe(in, out, length, key, sender, receiver)
u_char *in; /* application data */
u_char *out; /*
* put msg here, leave room for header!
* breaks if in and out (header stuff)
* overlap
*/
unsigned KRB4_32 length; /* of in data */
C_Block *key; /* encryption key for seed and ivec */
struct sockaddr_in *sender; /* sender address */
struct sockaddr_in *receiver; /* receiver address */
{
register u_char *p,*q;
unsigned KRB4_32 cksum;
unsigned KRB4_32 big_cksum[4];
unsigned KRB4_32 msg_secs;
unsigned KRB4_32 msg_usecs;
u_char msg_time_5ms;
KRB4_32 msg_time_sec;
int i;
/* Be really paranoid. */
if (sizeof(sender->sin_addr.s_addr) != 4)
return -1;
/*
* get the current time to use instead of a sequence #, since
* process lifetime may be shorter than the lifetime of a session
* key.
*/
msg_secs = TIME_GMT_UNIXSEC_US(&msg_usecs);
msg_time_sec = msg_secs;
msg_time_5ms = msg_usecs / 5000; /* 5ms quanta */
p = out;
*p++ = KRB_PROT_VERSION;
*p++ = AUTH_MSG_SAFE;
q = p; /* start for checksum stuff */
/* stuff input length */
KRB4_PUT32BE(p, length);
/* make all the stuff contiguous for checksum */
memcpy(p, in, length);
p += length;
/* stuff time 5ms */
*p++ = msg_time_5ms;
/* stuff source address */
if (sender->sin_family == AF_INET)
memcpy(p, &sender->sin_addr.s_addr, sizeof(sender->sin_addr.s_addr));
#ifdef KRB5_USE_INET6
else if (sender->sin_family == AF_INET6
&& IN6_IS_ADDR_V4MAPPED (&((struct sockaddr_in6 *)sender)->sin6_addr))
memcpy(p, 12+(char*)&((struct sockaddr_in6 *)sender)->sin6_addr, 4);
#endif
else
/* The address isn't one we can encode in 4 bytes -- but
that's okay if the receiver doesn't care. */
memset(p, 0, 4);
p += sizeof(sender->sin_addr.s_addr);
/*
* direction bit is the sign bit of the timestamp. Ok until
* 2038??
*/
if (krb4int_address_less (sender, receiver) == 1)
msg_time_sec = -msg_time_sec;
/* stuff time sec */
KRB4_PUT32BE(p, msg_time_sec);
#ifdef NOENCRYPTION
cksum = 0;
memset(big_cksum, 0, sizeof(big_cksum));
#else /* Do encryption */
/* calculate the checksum of length, timestamps, and input data */
cksum = quad_cksum(q, (unsigned KRB4_32 *)big_cksum,
p - q, 2, key);
#endif /* NOENCRYPTION */
DEB(("\ncksum = %u",cksum));
/* stuff checksum */
for (i = 0; i < 4; i++)
KRB4_PUT32BE(p, big_cksum[i]);
return p - out; /* resulting size */
}
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