1/* SPDX-License-Identifier: GPL-2.0 */
2#define MPPE_PAD                4      /* MPPE growth per frame */
3#define MPPE_MAX_KEY_LEN       16      /* largest key length (128-bit) */
4
5/* option bits for ccp_options.mppe */
6#define MPPE_OPT_40            0x01    /* 40 bit */
7#define MPPE_OPT_128           0x02    /* 128 bit */
8#define MPPE_OPT_STATEFUL      0x04    /* stateful mode */
9/* unsupported opts */
10#define MPPE_OPT_56            0x08    /* 56 bit */
11#define MPPE_OPT_MPPC          0x10    /* MPPC compression */
12#define MPPE_OPT_D             0x20    /* Unknown */
13#define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
14#define MPPE_OPT_UNKNOWN       0x40    /* Bits !defined in RFC 3078 were set */
15
16/*
17 * This is not nice ... the alternative is a bitfield struct though.
18 * And unfortunately, we cannot share the same bits for the option
19 * names above since C and H are the same bit.  We could do a u_int32
20 * but then we have to do a htonl() all the time and/or we still need
21 * to know which octet is which.
22 */
23#define MPPE_C_BIT             0x01    /* MPPC */
24#define MPPE_D_BIT             0x10    /* Obsolete, usage unknown */
25#define MPPE_L_BIT             0x20    /* 40-bit */
26#define MPPE_S_BIT             0x40    /* 128-bit */
27#define MPPE_M_BIT             0x80    /* 56-bit, not supported */
28#define MPPE_H_BIT             0x01    /* Stateless (in a different byte) */
29
30/* Does not include H bit; used for least significant octet only. */
31#define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
32
33/* Build a CI from mppe opts (see RFC 3078) */
34#define MPPE_OPTS_TO_CI(opts, ci)              \
35    do {                                       \
36       u_char *ptr = ci; /* u_char[4] */       \
37                                               \
38       /* H bit */                             \
39       if (opts & MPPE_OPT_STATEFUL)           \
40           *ptr++ = 0x0;                       \
41       else                                    \
42           *ptr++ = MPPE_H_BIT;                \
43       *ptr++ = 0;                             \
44       *ptr++ = 0;                             \
45                                               \
46       /* S,L bits */                          \
47       *ptr = 0;                               \
48       if (opts & MPPE_OPT_128)                \
49           *ptr |= MPPE_S_BIT;                 \
50       if (opts & MPPE_OPT_40)                 \
51           *ptr |= MPPE_L_BIT;                 \
52       /* M,D,C bits not supported */          \
53    } while (/* CONSTCOND */ 0)
54
55/* The reverse of the above */
56#define MPPE_CI_TO_OPTS(ci, opts)              \
57    do {                                       \
58       u_char *ptr = ci; /* u_char[4] */       \
59                                               \
60       opts = 0;                               \
61                                               \
62       /* H bit */                             \
63       if (!(ptr[0] & MPPE_H_BIT))             \
64           opts |= MPPE_OPT_STATEFUL;          \
65                                               \
66       /* S,L bits */                          \
67       if (ptr[3] & MPPE_S_BIT)                \
68           opts |= MPPE_OPT_128;               \
69       if (ptr[3] & MPPE_L_BIT)                \
70           opts |= MPPE_OPT_40;                \
71                                               \
72       /* M,D,C bits */                        \
73       if (ptr[3] & MPPE_M_BIT)                \
74           opts |= MPPE_OPT_56;                \
75       if (ptr[3] & MPPE_D_BIT)                \
76           opts |= MPPE_OPT_D;                 \
77       if (ptr[3] & MPPE_C_BIT)                \
78           opts |= MPPE_OPT_MPPC;              \
79                                               \
80       /* Other bits */                        \
81       if (ptr[0] & ~MPPE_H_BIT)               \
82           opts |= MPPE_OPT_UNKNOWN;           \
83       if (ptr[1] || ptr[2])                   \
84           opts |= MPPE_OPT_UNKNOWN;           \
85       if (ptr[3] & ~MPPE_ALL_BITS)            \
86           opts |= MPPE_OPT_UNKNOWN;           \
87    } while (/* CONSTCOND */ 0)
88