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Annotation of 43BSDReno/kerberosIV/krb/mk_safe.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * $Source: /mit/kerberos/src/lib/krb/RCS/mk_safe.c,v $
        !             3:  * $Author: jtkohl $
        !             4:  *
        !             5:  * Copyright 1986, 1987, 1988 by the Massachusetts Institute
        !             6:  * of Technology.
        !             7:  *
        !             8:  * For copying and distribution information, please see the file
        !             9:  * <mit-copyright.h>.
        !            10:  *
        !            11:  * This routine constructs a Kerberos 'safe msg', i.e. authenticated
        !            12:  * using a private session key to seed a checksum. Msg is NOT
        !            13:  * encrypted.
        !            14:  *
        !            15:  *      Note-- bcopy is used to avoid alignment problems on IBM RT
        !            16:  *
        !            17:  *      Returns either <0 ===> error, or resulting size of message
        !            18:  *
        !            19:  * Steve Miller    Project Athena  MIT/DEC
        !            20:  */
        !            21: 
        !            22: #ifndef lint
        !            23: static char *rcsid_mk_safe_c=
        !            24: "$Header: mk_safe.c,v 4.12 89/03/22 14:50:49 jtkohl Exp $";
        !            25: #endif /* lint */
        !            26: 
        !            27: #include <mit-copyright.h>
        !            28: 
        !            29: /* system include files */
        !            30: #include <stdio.h>
        !            31: #include <errno.h>
        !            32: #include <sys/types.h>
        !            33: #include <netinet/in.h>
        !            34: #include <sys/time.h>
        !            35: 
        !            36: /* application include files */
        !            37: #include <des.h>
        !            38: #include <krb.h>
        !            39: #include <prot.h>
        !            40: #include "lsb_addr_comp.h"
        !            41: 
        !            42: extern char *errmsg();
        !            43: extern int errno;
        !            44: extern int krb_debug;
        !            45: 
        !            46: /* static storage */
        !            47: 
        !            48: static u_long cksum;
        !            49: static C_Block big_cksum[2];
        !            50: static struct timeval msg_time;
        !            51: static u_char msg_time_5ms;
        !            52: static long msg_time_sec;
        !            53: 
        !            54: /*
        !            55:  * krb_mk_safe() constructs an AUTH_MSG_SAFE message.  It takes some
        !            56:  * user data "in" of "length" bytes and creates a packet in "out"
        !            57:  * consisting of the user data, a timestamp, and the sender's network
        !            58:  * address, followed by a checksum computed on the above, using the
        !            59:  * given "key".  The length of the resulting packet is returned.
        !            60:  *
        !            61:  * The "out" packet consists of:
        !            62:  *
        !            63:  * Size                        Variable                Field
        !            64:  * ----                        --------                -----
        !            65:  *
        !            66:  * 1 byte              KRB_PROT_VERSION        protocol version number
        !            67:  * 1 byte              AUTH_MSG_SAFE |         message type plus local
        !            68:  *                     HOST_BYTE_ORDER         byte order in low bit
        !            69:  *
        !            70:  * ===================== begin checksum ================================
        !            71:  * 
        !            72:  * 4 bytes             length                  length of user data
        !            73:  * length              in                      user data
        !            74:  * 1 byte              msg_time_5ms            timestamp milliseconds
        !            75:  * 4 bytes             sender->sin.addr.s_addr sender's IP address
        !            76:  *
        !            77:  * 4 bytes             msg_time_sec or         timestamp seconds with
        !            78:  *                     -msg_time_sec           direction in sign bit
        !            79:  *
        !            80:  * ======================= end checksum ================================
        !            81:  *
        !            82:  * 16 bytes            big_cksum               quadratic checksum of
        !            83:  *                                             above using "key"
        !            84:  */
        !            85: 
        !            86: long krb_mk_safe(in,out,length,key,sender,receiver)
        !            87:     u_char *in;                        /* application data */
        !            88:     u_char *out;               /*
        !            89:                                 * put msg here, leave room for header!
        !            90:                                 * breaks if in and out (header stuff)
        !            91:                                 * overlap
        !            92:                                 */
        !            93:     u_long length;             /* of in data */
        !            94:     C_Block *key;              /* encryption key for seed and ivec */
        !            95:     struct sockaddr_in *sender;        /* sender address */
        !            96:     struct sockaddr_in *receiver; /* receiver address */
        !            97: {
        !            98:     register u_char     *p,*q;
        !            99: 
        !           100:     /*
        !           101:      * get the current time to use instead of a sequence #, since
        !           102:      * process lifetime may be shorter than the lifetime of a session
        !           103:      * key.
        !           104:      */
        !           105:     if (gettimeofday(&msg_time,(struct timezone *)0)) {
        !           106:         return  -1;
        !           107:     }
        !           108:     msg_time_sec = (long) msg_time.tv_sec;
        !           109:     msg_time_5ms = msg_time.tv_usec/5000; /* 5ms quanta */
        !           110: 
        !           111:     p = out;
        !           112: 
        !           113:     *p++ = KRB_PROT_VERSION;
        !           114:     *p++ = AUTH_MSG_SAFE | HOST_BYTE_ORDER;
        !           115: 
        !           116:     q = p;                     /* start for checksum stuff */
        !           117:     /* stuff input length */
        !           118:     bcopy((char *)&length,(char *)p,sizeof(length));
        !           119:     p += sizeof(length);
        !           120: 
        !           121:     /* make all the stuff contiguous for checksum */
        !           122:     bcopy((char *)in,(char *)p,(int) length);
        !           123:     p += length;
        !           124: 
        !           125:     /* stuff time 5ms */
        !           126:     bcopy((char *)&msg_time_5ms,(char *)p,sizeof(msg_time_5ms));
        !           127:     p += sizeof(msg_time_5ms);
        !           128: 
        !           129:     /* stuff source address */
        !           130:     bcopy((char *) &sender->sin_addr.s_addr,(char *)p,
        !           131:           sizeof(sender->sin_addr.s_addr));
        !           132:     p += sizeof(sender->sin_addr.s_addr);
        !           133: 
        !           134:     /*
        !           135:      * direction bit is the sign bit of the timestamp.  Ok until
        !           136:      * 2038??
        !           137:      */
        !           138:     /* For compatibility with broken old code, compares are done in VAX 
        !           139:        byte order (LSBFIRST) */ 
        !           140:     if (lsb_net_ulong_less(sender->sin_addr.s_addr, /* src < recv */ 
        !           141:                          receiver->sin_addr.s_addr)==-1) 
        !           142:         msg_time_sec =  -msg_time_sec; 
        !           143:     else if (lsb_net_ulong_less(sender->sin_addr.s_addr, 
        !           144:                                receiver->sin_addr.s_addr)==0) 
        !           145:         if (lsb_net_ushort_less(sender->sin_port,receiver->sin_port) == -1) 
        !           146:             msg_time_sec = -msg_time_sec; 
        !           147:     /*
        !           148:      * all that for one tiny bit!  Heaven help those that talk to
        !           149:      * themselves.
        !           150:      */
        !           151: 
        !           152:     /* stuff time sec */
        !           153:     bcopy((char *)&msg_time_sec,(char *)p,sizeof(msg_time_sec));
        !           154:     p += sizeof(msg_time_sec);
        !           155: 
        !           156: #ifdef NOENCRYPTION
        !           157:     cksum = 0;
        !           158:     bzero(big_cksum, sizeof(big_cksum));
        !           159: #else /* Do encryption */
        !           160:     /* calculate the checksum of length, timestamps, and input data */
        !           161:     cksum = quad_cksum(q,big_cksum,p-q,2,key);
        !           162: #endif /* NOENCRYPTION */
        !           163:     if (krb_debug)
        !           164:         printf("\ncksum = %u",cksum);
        !           165: 
        !           166:     /* stuff checksum */
        !           167:     bcopy((char *)big_cksum,(char *)p,sizeof(big_cksum));
        !           168:     p += sizeof(big_cksum);
        !           169: 
        !           170:     return ((long)(p - out));  /* resulting size */
        !           171: 
        !           172: }

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