freebsd-skq/eBones/krb/mk_priv.c

/*
 * Copyright 1986, 1987, 1988 by the Massachusetts Institute
 * of Technology.
 * For copying and distribution information, please see the file
 * <Copyright.MIT>.
 *
 * This routine constructs a Kerberos 'private msg', i.e.
 * cryptographically sealed with a private session key.
 *
 * Note-- bcopy is used to avoid alignment problems on IBM RT.
 *
 * Note-- It's too bad that it did a long int compare on the RT before.
 *
 * Returns either < 0 ===> error, or resulting size of message
 *
 * Steve Miller    Project Athena  MIT/DEC
 *
 *	from: mk_priv.c,v 4.13 89/03/22 14:48:59 jtkohl Exp $
 *	$Id: mk_priv.c,v 1.2 1994/07/19 19:25:56 g89r4222 Exp $
 */

#ifndef lint
static char rcsid[] =
"$Id: mk_priv.c,v 1.2 1994/07/19 19:25:56 g89r4222 Exp $";
#endif /* lint */

/* system include files */
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/time.h>

/* application include files */
#include <des.h>
#include <krb.h>
#include <prot.h>
#include "lsb_addr_comp.h"

extern char *errmsg();
extern int errno;
extern int krb_debug;

/* static storage */


static u_long c_length;
static struct timeval msg_time;
static u_char msg_time_5ms;
static long msg_time_sec;

/*
 * krb_mk_priv() constructs an AUTH_MSG_PRIVATE 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.
#ifndef NOENCRYTION
 * The packet is encrypted by pcbc_encrypt(), using the given
 * "key" and "schedule".
#endif
 * The length of the resulting packet "out" is
 * returned.
 *
 * It is similar to krb_mk_safe() except for the additional key
 * schedule argument "schedule" and the fact that the data is encrypted
 * rather than appended with a checksum.  Also, the protocol version
 * number is "private_msg_ver", defined in krb_rd_priv.c, rather than
 * KRB_PROT_VERSION, defined in "krb.h".
 *
 * The "out" packet consists of:
 *
 * Size			Variable		Field
 * ----			--------		-----
 *
 * 1 byte		private_msg_ver		protocol version number
 * 1 byte		AUTH_MSG_PRIVATE |	message type plus local
 *			HOST_BYTE_ORDER		byte order in low bit
 *
 * 4 bytes		c_length		length of data
#ifndef NOENCRYPT
 * we encrypt from here with pcbc_encrypt
#endif
 * 
 * 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
 *
 * 0<=n<=7  bytes	pad to 8 byte multiple	zeroes
 */

long krb_mk_priv(in,out,length,schedule,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 */
    u_long length;              /* of in data */
    Key_schedule schedule;      /* precomputed key schedule */
    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;
    static       u_char *c_length_ptr;
    extern int private_msg_ver; /* in krb_rd_priv.c */

    /*
     * get the current time to use instead of a sequence #, since
     * process lifetime may be shorter than the lifetime of a session
     * key.
     */
    if (gettimeofday(&msg_time,(struct timezone *)0)) {
        return -1;
    }
    msg_time_sec = (long) msg_time.tv_sec;
    msg_time_5ms = msg_time.tv_usec/5000; /* 5ms quanta */

    p = out;

    *p++ = private_msg_ver;
    *p++ = AUTH_MSG_PRIVATE | HOST_BYTE_ORDER;

    /* calculate cipher length */
    c_length_ptr = p;
    p += sizeof(c_length);

    q = p;

    /* stuff input length */
    bcopy((char *)&length,(char *)p,sizeof(length));
    p += sizeof(length);

#ifdef NOENCRYPTION
    /* make all the stuff contiguous for checksum */
#else
    /* make all the stuff contiguous for checksum and encryption */
#endif
    bcopy((char *)in,(char *)p,(int) length);
    p += length;

    /* stuff time 5ms */
    bcopy((char *)&msg_time_5ms,(char *)p,sizeof(msg_time_5ms));
    p += sizeof(msg_time_5ms);

    /* stuff source address */
    bcopy((char *)&sender->sin_addr.s_addr,(char *)p,
          sizeof(sender->sin_addr.s_addr));
    p += sizeof(sender->sin_addr.s_addr);

    /*
     * direction bit is the sign bit of the timestamp.  Ok
     * until 2038??
     */
    /* For compatibility with broken old code, compares are done in VAX 
       byte order (LSBFIRST) */ 
    if (lsb_net_ulong_less(sender->sin_addr.s_addr, /* src < recv */ 
			  receiver->sin_addr.s_addr)==-1) 
        msg_time_sec =  -msg_time_sec; 
    else if (lsb_net_ulong_less(sender->sin_addr.s_addr, 
				receiver->sin_addr.s_addr)==0) 
        if (lsb_net_ushort_less(sender->sin_port,receiver->sin_port) == -1) 
            msg_time_sec = -msg_time_sec; 
    /* stuff time sec */
    bcopy((char *)&msg_time_sec,(char *)p,sizeof(msg_time_sec));
    p += sizeof(msg_time_sec);

    /*
     * All that for one tiny bit!  Heaven help those that talk to
     * themselves.
     */

#ifdef notdef
    /*
     * calculate the checksum of the length, address, sequence, and
     * inp data
     */
    cksum =  quad_cksum(q,NULL,p-q,0,key);
    if (krb_debug)
        printf("\ncksum = %u",cksum);
    /* stuff checksum */
    bcopy((char *) &cksum,(char *) p,sizeof(cksum));
    p += sizeof(cksum);
#endif

    /*
     * All the data have been assembled, compute length
     */

    c_length = p - q;
    c_length = ((c_length + sizeof(C_Block) -1)/sizeof(C_Block)) *
        sizeof(C_Block);
    /* stuff the length */
    bcopy((char *) &c_length,(char *)c_length_ptr,sizeof(c_length));

#ifndef NOENCRYPTION
    pcbc_encrypt((C_Block *)q,(C_Block *)q,(long)(p-q),schedule,key,ENCRYPT);
#endif /* NOENCRYPTION */

    return (q - out + c_length);        /* resulting size */
}