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      1 /*
      2  * mppe.h - Definitions for MPPE
      3  *
      4  * Copyright (c) 2008 Paul Mackerras. All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  *
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  *
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in
     15  *    the documentation and/or other materials provided with the
     16  *    distribution.
     17  *
     18  * 3. The name(s) of the authors of this software must not be used to
     19  *    endorse or promote products derived from this software without
     20  *    prior written permission.
     21  *
     22  * 4. Redistributions of any form whatsoever must retain the following
     23  *    acknowledgment:
     24  *    "This product includes software developed by Paul Mackerras
     25  *     <paulus (at) samba.org>".
     26  *
     27  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
     28  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
     29  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
     30  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     31  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
     32  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
     33  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     34  */
     35 
     36 #define MPPE_PAD		4	/* MPPE growth per frame */
     37 #define MPPE_MAX_KEY_LEN	16	/* largest key length (128-bit) */
     38 
     39 /* option bits for ccp_options.mppe */
     40 #define MPPE_OPT_40		0x01	/* 40 bit */
     41 #define MPPE_OPT_128		0x02	/* 128 bit */
     42 #define MPPE_OPT_STATEFUL	0x04	/* stateful mode */
     43 /* unsupported opts */
     44 #define MPPE_OPT_56		0x08	/* 56 bit */
     45 #define MPPE_OPT_MPPC		0x10	/* MPPC compression */
     46 #define MPPE_OPT_D		0x20	/* Unknown */
     47 #define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
     48 #define MPPE_OPT_UNKNOWN	0x40	/* Bits !defined in RFC 3078 were set */
     49 
     50 /*
     51  * This is not nice ... the alternative is a bitfield struct though.
     52  * And unfortunately, we cannot share the same bits for the option
     53  * names above since C and H are the same bit.  We could do a u_int32
     54  * but then we have to do a htonl() all the time and/or we still need
     55  * to know which octet is which.
     56  */
     57 #define MPPE_C_BIT		0x01	/* MPPC */
     58 #define MPPE_D_BIT		0x10	/* Obsolete, usage unknown */
     59 #define MPPE_L_BIT		0x20	/* 40-bit */
     60 #define MPPE_S_BIT		0x40	/* 128-bit */
     61 #define MPPE_M_BIT		0x80	/* 56-bit, not supported */
     62 #define MPPE_H_BIT		0x01	/* Stateless (in a different byte) */
     63 
     64 /* Does not include H bit; used for least significant octet only. */
     65 #define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
     66 
     67 /* Build a CI from mppe opts (see RFC 3078) */
     68 #define MPPE_OPTS_TO_CI(opts, ci)		\
     69     do {					\
     70 	u_char *ptr = ci; /* u_char[4] */	\
     71 						\
     72 	/* H bit */				\
     73 	if (opts & MPPE_OPT_STATEFUL)		\
     74 	    *ptr++ = 0x0;			\
     75 	else					\
     76 	    *ptr++ = MPPE_H_BIT;		\
     77 	*ptr++ = 0;				\
     78 	*ptr++ = 0;				\
     79 						\
     80 	/* S,L bits */				\
     81 	*ptr = 0;				\
     82 	if (opts & MPPE_OPT_128)		\
     83 	    *ptr |= MPPE_S_BIT;			\
     84 	if (opts & MPPE_OPT_40)			\
     85 	    *ptr |= MPPE_L_BIT;			\
     86 	/* M,D,C bits not supported */		\
     87     } while (/* CONSTCOND */ 0)
     88 
     89 /* The reverse of the above */
     90 #define MPPE_CI_TO_OPTS(ci, opts)		\
     91     do {					\
     92 	u_char *ptr = ci; /* u_char[4] */	\
     93 						\
     94 	opts = 0;				\
     95 						\
     96 	/* H bit */				\
     97 	if (!(ptr[0] & MPPE_H_BIT))		\
     98 	    opts |= MPPE_OPT_STATEFUL;		\
     99 						\
    100 	/* S,L bits */				\
    101 	if (ptr[3] & MPPE_S_BIT)		\
    102 	    opts |= MPPE_OPT_128;		\
    103 	if (ptr[3] & MPPE_L_BIT)		\
    104 	    opts |= MPPE_OPT_40;		\
    105 						\
    106 	/* M,D,C bits */			\
    107 	if (ptr[3] & MPPE_M_BIT)		\
    108 	    opts |= MPPE_OPT_56;		\
    109 	if (ptr[3] & MPPE_D_BIT)		\
    110 	    opts |= MPPE_OPT_D;			\
    111 	if (ptr[3] & MPPE_C_BIT)		\
    112 	    opts |= MPPE_OPT_MPPC;		\
    113 						\
    114 	/* Other bits */			\
    115 	if (ptr[0] & ~MPPE_H_BIT)		\
    116 	    opts |= MPPE_OPT_UNKNOWN;		\
    117 	if (ptr[1] || ptr[2])			\
    118 	    opts |= MPPE_OPT_UNKNOWN;		\
    119 	if (ptr[3] & ~MPPE_ALL_BITS)		\
    120 	    opts |= MPPE_OPT_UNKNOWN;		\
    121     } while (/* CONSTCOND */ 0)
    122