xref: /linux/drivers/net/ppp/ppp_mppe.h (revision 498495dba268b20e8eadd7fe93c140c68b6cc9d2)
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